xref: /netbsd/src/external/cddl/osnet/dist/uts/common/dtrace/dtrace.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 * $FreeBSD: head/sys/cddl/contrib/opensolaris/uts/common/dtrace/dtrace.c 313266 2017-02-05 02:47:34Z markj $
 */

/*
 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2016, Joyent, Inc. All rights reserved.
 * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
 */

/*
 * DTrace - Dynamic Tracing for Solaris
 *
 * This is the implementation of the Solaris Dynamic Tracing framework
 * (DTrace).  The user-visible interface to DTrace is described at length in
 * the "Solaris Dynamic Tracing Guide".  The interfaces between the libdtrace
 * library, the in-kernel DTrace framework, and the DTrace providers are
 * described in the block comments in the <sys/dtrace.h> header file.  The
 * internal architecture of DTrace is described in the block comments in the
 * <sys/dtrace_impl.h> header file.  The comments contained within the DTrace
 * implementation very much assume mastery of all of these sources; if one has
 * an unanswered question about the implementation, one should consult them
 * first.
 *
 * The functions here are ordered roughly as follows:
 *
 *   - Probe context functions
 *   - Probe hashing functions
 *   - Non-probe context utility functions
 *   - Matching functions
 *   - Provider-to-Framework API functions
 *   - Probe management functions
 *   - DIF object functions
 *   - Format functions
 *   - Predicate functions
 *   - ECB functions
 *   - Buffer functions
 *   - Enabling functions
 *   - DOF functions
 *   - Anonymous enabling functions
 *   - Consumer state functions
 *   - Helper functions
 *   - Hook functions
 *   - Driver cookbook functions
 *
 * Each group of functions begins with a block comment labelled the "DTrace
 * [Group] Functions", allowing one to find each block by searching forward
 * on capital-f functions.
 */
#ifdef __NetBSD__
#define   __MUTEX_PRIVATE
#define __RWLOCK_PRIVATE
#include <sys/proc.h>
#endif

#include <sys/errno.h>
#ifndef illumos
#include <sys/time.h>
#endif
#include <sys/stat.h>
#include <sys/modctl.h>
#include <sys/conf.h>
#include <sys/systm.h>
#ifdef illumos
#include <sys/ddi.h>
#include <sys/sunddi.h>
#endif
#include <sys/cpuvar.h>
#include <sys/kmem.h>
#ifdef illumos
#include <sys/strsubr.h>
#endif
#include <sys/sysmacros.h>
#include <sys/dtrace_impl.h>
#include <sys/atomic.h>
#include <sys/cmn_err.h>
#ifdef illumos
#include <sys/mutex_impl.h>
#include <sys/rwlock_impl.h>
#endif
#include <sys/ctf_api.h>
#ifdef illumos
#include <sys/panic.h>
#include <sys/priv_impl.h>
#endif
#include <sys/policy.h>
#ifdef illumos
#include <sys/cred_impl.h>
#include <sys/procfs_isa.h>
#endif
#include <sys/taskq.h>
#ifdef illumos
#include <sys/mkdev.h>
#include <sys/kdi.h>
#endif
#include <sys/zone.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include "strtolctype.h"

/* FreeBSD includes: */
#ifdef __FreeBSD__
#include <sys/callout.h>
#include <sys/ctype.h>
#include <sys/eventhandler.h>
#include <sys/limits.h>
#include <sys/linker.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/ptrace.h>
#include <sys/random.h>
#include <sys/rwlock.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#endif

#ifdef __NetBSD__
#include <sys/cred.h>
#include <sys/callout.h>
#include <sys/ctype.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/random.h>
#include <sys/rwlock.h>
#include <sys/sysctl.h>
#include <sys/mutex_impl.h>
#include <sys/rwlock_impl.h>
#include <sys/mkdev.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/vmem.h>
#include <sys/module.h>
#include <sys/cpu.h>
#endif

#ifndef illumos

#include <sys/dtrace_bsd.h>

#include "dtrace_xoroshiro128_plus.h"

#include <netinet/in.h>

#include "dtrace_cddl.h"
#include "dtrace_debug.c"

#ifdef __NetBSD__
struct dtrace_state_worker *dtrace_state_worker_add(void (*fn)(dtrace_state_t *),
    dtrace_state_t *state, hrtime_t interval);
void dtrace_state_worker_remove(struct dtrace_state_worker *w);

modctl_t *mod_nbsd;

#endif /* __NetBSD__ */

#endif /* !illumos */


/*
 * DTrace Tunable Variables
 *
 * The following variables may be tuned by adding a line to /etc/system that
 * includes both the name of the DTrace module ("dtrace") and the name of the
 * variable.  For example:
 *
 *   set dtrace:dtrace_destructive_disallow = 1
 *
 * In general, the only variables that one should be tuning this way are those
 * that affect system-wide DTrace behavior, and for which the default behavior
 * is undesirable.  Most of these variables are tunable on a per-consumer
 * basis using DTrace options, and need not be tuned on a system-wide basis.
 * When tuning these variables, avoid pathological values; while some attempt
 * is made to verify the integrity of these variables, they are not considered
 * part of the supported interface to DTrace, and they are therefore not
 * checked comprehensively.  Further, these variables should not be tuned
 * dynamically via "mdb -kw" or other means; they should only be tuned via
 * /etc/system.
 */
int                 dtrace_destructive_disallow = 0;
#ifndef illumos
/* Positive logic version of dtrace_destructive_disallow for loader tunable */
int                 dtrace_allow_destructive = 1;
#endif
dtrace_optval_t     dtrace_nonroot_maxsize = (16 * 1024 * 1024);
size_t              dtrace_difo_maxsize = (256 * 1024);
dtrace_optval_t     dtrace_dof_maxsize = (8 * 1024 * 1024);
size_t              dtrace_statvar_maxsize = (16 * 1024);
size_t              dtrace_actions_max = (16 * 1024);
size_t              dtrace_retain_max = 1024;
dtrace_optval_t     dtrace_helper_actions_max = 128;
dtrace_optval_t     dtrace_helper_providers_max = 32;
dtrace_optval_t     dtrace_dstate_defsize = (1 * 1024 * 1024);
size_t              dtrace_strsize_default = 256;
dtrace_optval_t     dtrace_cleanrate_default = 9900990;               /* 101 hz */
dtrace_optval_t     dtrace_cleanrate_min = 200000;                              /* 5000 hz */
dtrace_optval_t     dtrace_cleanrate_max = (uint64_t)60 * NANOSEC;    /* 1/minute */
dtrace_optval_t     dtrace_aggrate_default = NANOSEC;                 /* 1 hz */
dtrace_optval_t     dtrace_statusrate_default = NANOSEC;              /* 1 hz */
dtrace_optval_t dtrace_statusrate_max = (hrtime_t)10 * NANOSEC;        /* 6/minute */
dtrace_optval_t     dtrace_switchrate_default = NANOSEC;              /* 1 hz */
dtrace_optval_t     dtrace_nspec_default = 1;
dtrace_optval_t     dtrace_specsize_default = 32 * 1024;
dtrace_optval_t dtrace_stackframes_default = 20;
dtrace_optval_t dtrace_ustackframes_default = 20;
dtrace_optval_t dtrace_jstackframes_default = 50;
dtrace_optval_t dtrace_jstackstrsize_default = 512;
int                 dtrace_msgdsize_max = 128;
hrtime_t  dtrace_chill_max = MSEC2NSEC(500);                /* 500 ms */
hrtime_t  dtrace_chill_interval = NANOSEC;                  /* 1000 ms */
int                 dtrace_devdepth_max = 32;
int                 dtrace_err_verbose;
hrtime_t  dtrace_deadman_interval = NANOSEC;
hrtime_t  dtrace_deadman_timeout = (hrtime_t)10 * NANOSEC;
hrtime_t  dtrace_deadman_user = (hrtime_t)30 * NANOSEC;
hrtime_t  dtrace_unregister_defunct_reap = (hrtime_t)60 * NANOSEC;
#ifndef illumos
int                 dtrace_memstr_max = 4096;
#endif

/*
 * DTrace External Variables
 *
 * As dtrace(7D) is a kernel module, any DTrace variables are obviously
 * available to DTrace consumers via the backtick (`) syntax.  One of these,
 * dtrace_zero, is made deliberately so:  it is provided as a source of
 * well-known, zero-filled memory.  While this variable is not documented,
 * it is used by some translators as an implementation detail.
 */
const char          dtrace_zero[256] = { 0 };     /* zero-filled memory */

/*
 * DTrace Internal Variables
 */
#ifdef illumos
static dev_info_t   *dtrace_devi;                 /* device info */
#endif
#ifdef illumos
static vmem_t                 *dtrace_arena;                /* probe ID arena */
static vmem_t                 *dtrace_minor;                /* minor number arena */
#else
static taskq_t                *dtrace_taskq;                /* task queue */
#ifdef __NetBSD__
static vmem_t                 *dtrace_arena;                /* probe ID arena */
#else
static struct unrhdr          *dtrace_arena;                /* Probe ID number.     */
#endif
#endif
static dtrace_probe_t         **dtrace_probes;    /* array of all probes */
static int                    dtrace_nprobes;               /* number of probes */
static dtrace_provider_t *dtrace_provider;        /* provider list */
static dtrace_meta_t          *dtrace_meta_pid;   /* user-land meta provider */
static int                    dtrace_opens;                 /* number of opens */
static int                    dtrace_helpers;               /* number of helpers */
static int                    dtrace_getf;                  /* number of unpriv getf()s */
#ifdef illumos
static void                   *dtrace_softstate;  /* softstate pointer */
#endif
static dtrace_hash_t          *dtrace_bymod;                /* probes hashed by module */
static dtrace_hash_t          *dtrace_byfunc;               /* probes hashed by function */
static dtrace_hash_t          *dtrace_byname;               /* probes hashed by name */
static dtrace_toxrange_t *dtrace_toxrange;        /* toxic range array */
static int                    dtrace_toxranges;   /* number of toxic ranges */
static int                    dtrace_toxranges_max;         /* size of toxic range array */
static dtrace_anon_t          dtrace_anon;                  /* anonymous enabling */
static kmem_cache_t *dtrace_state_cache;          /* cache for dynamic state */
static uint64_t               dtrace_vtime_references; /* number of vtimestamp refs */
static kthread_t    *dtrace_panicked;   /* panicking thread */
static dtrace_ecb_t *dtrace_ecb_create_cache; /* cached created ECB */
static dtrace_genid_t         dtrace_probegen;    /* current probe generation */
static dtrace_helpers_t *dtrace_deferred_pid;     /* deferred helper list */
static dtrace_enabling_t *dtrace_retained;        /* list of retained enablings */
static dtrace_genid_t         dtrace_retained_gen;          /* current retained enab gen */
static dtrace_dynvar_t        dtrace_dynhash_sink;          /* end of dynamic hash chains */
static int                    dtrace_dynvar_failclean; /* dynvars failed to clean */
#ifdef __FreeBSD__
static struct mtx   dtrace_unr_mtx;
MTX_SYSINIT(dtrace_unr_mtx, &dtrace_unr_mtx, "Unique resource identifier", MTX_DEF);
static eventhandler_tag       dtrace_kld_load_tag;
static eventhandler_tag       dtrace_kld_unload_try_tag;
#endif

/*
 * DTrace Locking
 * DTrace is protected by three (relatively coarse-grained) locks:
 *
 * (1) dtrace_lock is required to manipulate essentially any DTrace state,
 *     including enabling state, probes, ECBs, consumer state, helper state,
 *     etc.  Importantly, dtrace_lock is _not_ required when in probe context;
 *     probe context is lock-free -- synchronization is handled via the
 *     dtrace_sync() cross call mechanism.
 *
 * (2) dtrace_provider_lock is required when manipulating provider state, or
 *     when provider state must be held constant.
 *
 * (3) dtrace_meta_lock is required when manipulating meta provider state, or
 *     when meta provider state must be held constant.
 *
 * The lock ordering between these three locks is dtrace_meta_lock before
 * dtrace_provider_lock before dtrace_lock.  (In particular, there are
 * several places where dtrace_provider_lock is held by the framework as it
 * calls into the providers -- which then call back into the framework,
 * grabbing dtrace_lock.)
 *
 * There are two other locks in the mix:  mod_lock and cpu_lock.  With respect
 * to dtrace_provider_lock and dtrace_lock, cpu_lock continues its historical
 * role as a coarse-grained lock; it is acquired before both of these locks.
 * With respect to dtrace_meta_lock, its behavior is stranger:  cpu_lock must
 * be acquired _between_ dtrace_meta_lock and any other DTrace locks.
 * mod_lock is similar with respect to dtrace_provider_lock in that it must be
 * acquired _between_ dtrace_provider_lock and dtrace_lock.
 */
static kmutex_t               dtrace_lock;                  /* probe state lock */
static kmutex_t               dtrace_provider_lock;         /* provider state lock */
static kmutex_t               dtrace_meta_lock;   /* meta-provider state lock */

#ifndef illumos
/* XXX FreeBSD hacks. */
#ifdef __FreeBSD__
static kmutex_t               mod_lock;
#endif

#define cr_suid               cr_svuid
#define cr_sgid               cr_svgid
#define   ipaddr_t  in_addr_t
#define mod_modname pathname
#define vuprintf    vprintf
#ifdef __NetBSD__
#define ttoproc(_a) ((_a)->l_proc)
#else
#define ttoproc(_a) ((_a)->td_proc)
#endif
#define crgetzoneid(_a)       0
#define SNOCD                 0
#define CPU_ON_INTR(_a)       0

#define PRIV_EFFECTIVE                  (1 << 0)
#define PRIV_DTRACE_KERNEL    (1 << 1)
#define PRIV_DTRACE_PROC      (1 << 2)
#define PRIV_DTRACE_USER      (1 << 3)
#define PRIV_PROC_OWNER                 (1 << 4)
#define PRIV_PROC_ZONE                  (1 << 5)
#define PRIV_ALL              ~0

SYSCTL_NODE(_debug, OID_AUTO, dtrace, CTLFLAG_RD, 0, "DTrace Information");
SYSCTL_DECL(_debug_dtrace);
SYSCTL_DECL(_kern_dtrace);
#endif

#ifdef illumos
#define curcpu_id   CPU->cpu_id
#endif
#ifdef __FreeBSD__
#define curcpu_id   curcpu
#endif
#ifdef __NetBSD__
#define curcpu_id   cpu_number()
#endif


/*
 * DTrace Provider Variables
 *
 * These are the variables relating to DTrace as a provider (that is, the
 * provider of the BEGIN, END, and ERROR probes).
 */
static dtrace_pattr_t         dtrace_provider_attr = {
{ DTRACE_STABILITY_STABLE, DTRACE_STABILITY_STABLE, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_STABLE, DTRACE_STABILITY_STABLE, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_STABLE, DTRACE_STABILITY_STABLE, DTRACE_CLASS_COMMON },
};

static int
dtrace_nullop(void)
{

          return 0;
}

static dtrace_pops_t          dtrace_provider_ops = {
          (void (*)(void *, dtrace_probedesc_t *))dtrace_nullop,
          (void (*)(void *, modctl_t *))dtrace_nullop,
          (int (*)(void *, dtrace_id_t, void *))dtrace_nullop,
          (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
          (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
          (void (*)(void *, dtrace_id_t, void *))dtrace_nullop,
          NULL,
          NULL,
          NULL,
          (void (*)(void *, dtrace_id_t, void *))dtrace_nullop
};

static dtrace_id_t  dtrace_probeid_begin;         /* special BEGIN probe */
static dtrace_id_t  dtrace_probeid_end; /* special END probe */
dtrace_id_t                   dtrace_probeid_error;         /* special ERROR probe */

/*
 * DTrace Helper Tracing Variables
 *
 * These variables should be set dynamically to enable helper tracing.  The
 * only variables that should be set are dtrace_helptrace_enable (which should
 * be set to a non-zero value to allocate helper tracing buffers on the next
 * open of /dev/dtrace) and dtrace_helptrace_disable (which should be set to a
 * non-zero value to deallocate helper tracing buffers on the next close of
 * /dev/dtrace).  When (and only when) helper tracing is disabled, the
 * buffer size may also be set via dtrace_helptrace_bufsize.
 */
int                           dtrace_helptrace_enable = 0;
int                           dtrace_helptrace_disable = 0;
int                           dtrace_helptrace_bufsize = 16 * 1024 * 1024;
uint32_t            dtrace_helptrace_nlocals;
static dtrace_helptrace_t *dtrace_helptrace_buffer;
static uint32_t               dtrace_helptrace_next = 0;
static int                    dtrace_helptrace_wrapped = 0;

/*
 * DTrace Error Hashing
 *
 * On DEBUG kernels, DTrace will track the errors that has seen in a hash
 * table.  This is very useful for checking coverage of tests that are
 * expected to induce DIF or DOF processing errors, and may be useful for
 * debugging problems in the DIF code generator or in DOF generation .  The
 * error hash may be examined with the ::dtrace_errhash MDB dcmd.
 */
#ifdef DEBUG
static dtrace_errhash_t       dtrace_errhash[DTRACE_ERRHASHSZ];
static const char *dtrace_errlast;
static kthread_t *dtrace_errthread;
static kmutex_t dtrace_errlock;
#endif

/*
 * DTrace Macros and Constants
 *
 * These are various macros that are useful in various spots in the
 * implementation, along with a few random constants that have no meaning
 * outside of the implementation.  There is no real structure to this cpp
 * mishmash -- but is there ever?
 */
#define   DTRACE_HASHSTR(hash, probe)   \
          dtrace_hash_str(*((char **)((uintptr_t)(probe) + (hash)->dth_stroffs)))

#define   DTRACE_HASHNEXT(hash, probe)  \
          (dtrace_probe_t **)((uintptr_t)(probe) + (hash)->dth_nextoffs)

#define   DTRACE_HASHPREV(hash, probe)  \
          (dtrace_probe_t **)((uintptr_t)(probe) + (hash)->dth_prevoffs)

#define   DTRACE_HASHEQ(hash, lhs, rhs) \
          (strcmp(*((char **)((uintptr_t)(lhs) + (hash)->dth_stroffs)), \
              *((char **)((uintptr_t)(rhs) + (hash)->dth_stroffs))) == 0)

#define   DTRACE_AGGHASHSIZE_SLEW                 17

#define   DTRACE_V4MAPPED_OFFSET                  (sizeof (uint32_t) * 3)

/*
 * The key for a thread-local variable consists of the lower 61 bits of the
 * t_did, plus the 3 bits of the highest active interrupt above LOCK_LEVEL.
 * We add DIF_VARIABLE_MAX to t_did to assure that the thread key is never
 * equal to a variable identifier.  This is necessary (but not sufficient) to
 * assure that global associative arrays never collide with thread-local
 * variables.  To guarantee that they cannot collide, we must also define the
 * order for keying dynamic variables.  That order is:
 *
 *   [ key0 ] ... [ keyn ] [ variable-key ] [ tls-key ]
 *
 * Because the variable-key and the tls-key are in orthogonal spaces, there is
 * no way for a global variable key signature to match a thread-local key
 * signature.
 */
#ifdef illumos
#define   DTRACE_TLS_THRKEY(where) { \
          uint_t intr = 0; \
          uint_t actv = CPU->cpu_intr_actv >> (LOCK_LEVEL + 1); \
          for (; actv; actv >>= 1) \
                    intr++; \
          ASSERT(intr < (1 << 3)); \
          (where) = ((curthread->t_did + DIF_VARIABLE_MAX) & \
              (((uint64_t)1 << 61) - 1)) | ((uint64_t)intr << 61); \
}
#endif
#ifdef __FreeBSD__
#define   DTRACE_TLS_THRKEY(where) { \
          solaris_cpu_t *_c = &solaris_cpu[curcpu]; \
          uint_t intr = 0; \
          uint_t actv = _c->cpu_intr_actv; \
          for (; actv; actv >>= 1) \
                    intr++; \
          ASSERT(intr < (1 << 3)); \
          (where) = ((curthread->td_tid + DIF_VARIABLE_MAX) & \
              (((uint64_t)1 << 61) - 1)) | ((uint64_t)intr << 61); \
}
#endif
#ifdef __NetBSD__
#define   DTRACE_TLS_THRKEY(where) { \
          uint_t intr = 0; \
          (where) = ((curthread->l_lid + (curthread->l_proc->p_pid << 16) + \
                        DIF_VARIABLE_MAX) & \
                        (((uint64_t)1 << 61) - 1)) | ((uint64_t)intr << 61); \
}
#endif

#define   DT_BSWAP_8(x)       ((x) & 0xff)
#define   DT_BSWAP_16(x)      ((DT_BSWAP_8(x) << 8) | DT_BSWAP_8((x) >> 8))
#define   DT_BSWAP_32(x)      ((DT_BSWAP_16(x) << 16) | DT_BSWAP_16((x) >> 16))
#define   DT_BSWAP_64(x)      ((DT_BSWAP_32(x) << 32) | DT_BSWAP_32((x) >> 32))

#define   DT_MASK_LO 0x00000000FFFFFFFFULL

#define   DTRACE_STORE(type, tomax, offset, what) \
          *((type *)((uintptr_t)(tomax) + (uintptr_t)offset)) = (type)(what);

#ifndef __x86
#define   DTRACE_ALIGNCHECK(addr, size, flags)                                  \
          if (addr & (size - 1)) {                                              \
                    *flags |= CPU_DTRACE_BADALIGN;                                        \
                    cpu_core[curcpu_id].cpuc_dtrace_illval = addr;    \
                    return (0);                                                           \
          }
#else
#define   DTRACE_ALIGNCHECK(addr, size, flags)
#endif

/*
 * Test whether a range of memory starting at testaddr of size testsz falls
 * within the range of memory described by addr, sz.  We take care to avoid
 * problems with overflow and underflow of the unsigned quantities, and
 * disallow all negative sizes.  Ranges of size 0 are allowed.
 */
#define   DTRACE_INRANGE(testaddr, testsz, baseaddr, basesz) \
          ((testaddr) - (uintptr_t)(baseaddr) < (basesz) && \
          (testaddr) + (testsz) - (uintptr_t)(baseaddr) <= (basesz) && \
          (testaddr) + (testsz) >= (testaddr))

#define   DTRACE_RANGE_REMAIN(remp, addr, baseaddr, basesz)           \
do {                                                                                      \
          if ((remp) != NULL) {                                                           \
                    *(remp) = (uintptr_t)(baseaddr) + (basesz) - (addr);        \
          }                                                                               \
_NOTE(CONSTCOND) } while (0)


/*
 * Test whether alloc_sz bytes will fit in the scratch region.  We isolate
 * alloc_sz on the righthand side of the comparison in order to avoid overflow
 * or underflow in the comparison with it.  This is simpler than the INRANGE
 * check above, because we know that the dtms_scratch_ptr is valid in the
 * range.  Allocations of size zero are allowed.
 */
#define   DTRACE_INSCRATCH(mstate, alloc_sz) \
          ((mstate)->dtms_scratch_base + (mstate)->dtms_scratch_size - \
          (mstate)->dtms_scratch_ptr >= (alloc_sz))

#define   DTRACE_LOADFUNC(bits)                                                           \
/*CSTYLED*/                                                                               \
uint##bits##_t                                                                            \
dtrace_load##bits(uintptr_t addr)                                               \
{                                                                                         \
          size_t size = bits / NBBY;                                            \
          /*CSTYLED*/                                                                     \
          uint##bits##_t rval;                                                            \
          int i;                                                                          \
          volatile uint16_t *flags = (volatile uint16_t *)            \
              &cpu_core[curcpu_id].cpuc_dtrace_flags;                           \
                                                                                          \
          DTRACE_ALIGNCHECK(addr, size, flags);                                 \
                                                                                          \
          for (i = 0; i < dtrace_toxranges; i++) {                              \
                    if (addr >= dtrace_toxrange[i].dtt_limit)                   \
                              continue;                                         \
                                                                                          \
                    if (addr + size <= dtrace_toxrange[i].dtt_base)             \
                              continue;                                         \
                                                                                          \
                    /*                                                                    \
                     * This address falls within a toxic region; return 0.      \
                     */                                                                   \
                    *flags |= CPU_DTRACE_BADADDR;                               \
                    cpu_core[curcpu_id].cpuc_dtrace_illval = addr;              \
                    return (0);                                                           \
          }                                                                               \
                                                                                          \
          *flags |= CPU_DTRACE_NOFAULT;                                         \
          /*CSTYLED*/                                                                     \
          rval = *((volatile uint##bits##_t *)addr);                            \
          *flags &= ~CPU_DTRACE_NOFAULT;                                                  \
                                                                                          \
          return (!(*flags & CPU_DTRACE_FAULT) ? rval : 0);           \
}

#ifdef _LP64
#define   dtrace_loadptr      dtrace_load64
#else
#define   dtrace_loadptr      dtrace_load32
#endif

#define   DTRACE_DYNHASH_FREE 0
#define   DTRACE_DYNHASH_SINK 1
#define   DTRACE_DYNHASH_VALID          2

#define   DTRACE_MATCH_FAIL   -1
#define   DTRACE_MATCH_NEXT   0
#define   DTRACE_MATCH_DONE   1
#define   DTRACE_ANCHORED(probe)        ((probe)->dtpr_func[0] != '\0')
#define   DTRACE_STATE_ALIGN  64

#define   DTRACE_FLAGS2FLT(flags)                                                         \
          (((flags) & CPU_DTRACE_BADADDR) ? DTRACEFLT_BADADDR :                 \
          ((flags) & CPU_DTRACE_ILLOP) ? DTRACEFLT_ILLOP :            \
          ((flags) & CPU_DTRACE_DIVZERO) ? DTRACEFLT_DIVZERO :                  \
          ((flags) & CPU_DTRACE_KPRIV) ? DTRACEFLT_KPRIV :            \
          ((flags) & CPU_DTRACE_UPRIV) ? DTRACEFLT_UPRIV :            \
          ((flags) & CPU_DTRACE_TUPOFLOW) ?  DTRACEFLT_TUPOFLOW :               \
          ((flags) & CPU_DTRACE_BADALIGN) ?  DTRACEFLT_BADALIGN :               \
          ((flags) & CPU_DTRACE_NOSCRATCH) ?  DTRACEFLT_NOSCRATCH :   \
          ((flags) & CPU_DTRACE_BADSTACK) ?  DTRACEFLT_BADSTACK :               \
          DTRACEFLT_UNKNOWN)

#define   DTRACEACT_ISSTRING(act)                                                         \
          ((act)->dta_kind == DTRACEACT_DIFEXPR &&                              \
          (act)->dta_difo->dtdo_rtype.dtdt_kind == DIF_TYPE_STRING)

/* Function prototype definitions: */
static size_t dtrace_strlen(const char *, size_t);
static dtrace_probe_t *dtrace_probe_lookup_id(dtrace_id_t id);
static void dtrace_enabling_provide(dtrace_provider_t *);
static int dtrace_enabling_match(dtrace_enabling_t *, int *);
static void dtrace_enabling_matchall(void);
static void dtrace_enabling_reap(void);
static dtrace_state_t *dtrace_anon_grab(void);
static uint64_t dtrace_helper(int, dtrace_mstate_t *,
    dtrace_state_t *, uint64_t, uint64_t);
static dtrace_helpers_t *dtrace_helpers_create(proc_t *);
static void dtrace_buffer_drop(dtrace_buffer_t *);
static int dtrace_buffer_consumed(dtrace_buffer_t *, hrtime_t when);
static intptr_t dtrace_buffer_reserve(dtrace_buffer_t *, size_t, size_t,
    dtrace_state_t *, dtrace_mstate_t *);
static int dtrace_state_option(dtrace_state_t *, dtrace_optid_t,
    dtrace_optval_t);
static int dtrace_ecb_create_enable(dtrace_probe_t *, void *);
static void dtrace_helper_provider_destroy(dtrace_helper_provider_t *);
uint16_t dtrace_load16(uintptr_t);
uint32_t dtrace_load32(uintptr_t);
uint64_t dtrace_load64(uintptr_t);
uint8_t dtrace_load8(uintptr_t);
void dtrace_dynvar_clean(dtrace_dstate_t *);
dtrace_dynvar_t *dtrace_dynvar(dtrace_dstate_t *, uint_t, dtrace_key_t *,
    size_t, dtrace_dynvar_op_t, dtrace_mstate_t *, dtrace_vstate_t *);
uintptr_t dtrace_dif_varstr(uintptr_t, dtrace_state_t *, dtrace_mstate_t *);
static int dtrace_priv_proc(dtrace_state_t *);
static void dtrace_getf_barrier(void);
static int dtrace_canload_remains(uint64_t, size_t, size_t *,
    dtrace_mstate_t *, dtrace_vstate_t *);
static int dtrace_canstore_remains(uint64_t, size_t, size_t *,
    dtrace_mstate_t *, dtrace_vstate_t *);

/*
 * DTrace Probe Context Functions
 *
 * These functions are called from probe context.  Because probe context is
 * any context in which C may be called, arbitrarily locks may be held,
 * interrupts may be disabled, we may be in arbitrary dispatched state, etc.
 * As a result, functions called from probe context may only call other DTrace
 * support functions -- they may not interact at all with the system at large.
 * (Note that the ASSERT macro is made probe-context safe by redefining it in
 * terms of dtrace_assfail(), a probe-context safe function.) If arbitrary
 * loads are to be performed from probe context, they _must_ be in terms of
 * the safe dtrace_load*() variants.
 *
 * Some functions in this block are not actually called from probe context;
 * for these functions, there will be a comment above the function reading
 * "Note:  not called from probe context."
 */
void
dtrace_panic(const char *format, ...)
{
          va_list alist;

          va_start(alist, format);
#ifndef illumos
          vpanic(format, alist);
#else
          dtrace_vpanic(format, alist);
#endif
          va_end(alist);
}

int
dtrace_assfail(const char *a, const char *f, int l)
{
          dtrace_panic("assertion failed: %s, file: %s, line: %d", a, f, l);

          /*
           * We just need something here that even the most clever compiler
           * cannot optimize away.
           */
          return (a[(uintptr_t)f]);
}

/*
 * Atomically increment a specified error counter from probe context.
 */
static void
dtrace_error(uint32_t *counter)
{
          /*
           * Most counters stored to in probe context are per-CPU counters.
           * However, there are some error conditions that are sufficiently
           * arcane that they don't merit per-CPU storage.  If these counters
           * are incremented concurrently on different CPUs, scalability will be
           * adversely affected -- but we don't expect them to be white-hot in a
           * correctly constructed enabling...
           */
          uint32_t oval, nval;

          do {
                    oval = *counter;

                    if ((nval = oval + 1) == 0) {
                              /*
                               * If the counter would wrap, set it to 1 -- assuring
                               * that the counter is never zero when we have seen
                               * errors.  (The counter must be 32-bits because we
                               * aren't guaranteed a 64-bit compare&swap operation.)
                               * To save this code both the infamy of being fingered
                               * by a priggish news story and the indignity of being
                               * the target of a neo-puritan witch trial, we're
                               * carefully avoiding any colorful description of the
                               * likelihood of this condition -- but suffice it to
                               * say that it is only slightly more likely than the
                               * overflow of predicate cache IDs, as discussed in
                               * dtrace_predicate_create().
                               */
                              nval = 1;
                    }
          } while (dtrace_cas32(counter, oval, nval) != oval);
}

/*
 * Use the DTRACE_LOADFUNC macro to define functions for each of loading a
 * uint8_t, a uint16_t, a uint32_t and a uint64_t.
 */
/* BEGIN CSTYLED */
DTRACE_LOADFUNC(8)
DTRACE_LOADFUNC(16)
DTRACE_LOADFUNC(32)
DTRACE_LOADFUNC(64)
/* END CSTYLED */

static int
dtrace_inscratch(uintptr_t dest, size_t size, dtrace_mstate_t *mstate)
{
          if (dest < mstate->dtms_scratch_base)
                    return (0);

          if (dest + size < dest)
                    return (0);

          if (dest + size > mstate->dtms_scratch_ptr)
                    return (0);

          return (1);
}

static int
dtrace_canstore_statvar(uint64_t addr, size_t sz, size_t *remain,
    dtrace_statvar_t **svars, int nsvars)
{
          int i;
          size_t maxglobalsize, maxlocalsize;

          if (nsvars == 0)
                    return (0);

          maxglobalsize = dtrace_statvar_maxsize + sizeof (uint64_t);
          maxlocalsize = maxglobalsize * NCPU;

          for (i = 0; i < nsvars; i++) {
                    dtrace_statvar_t *svar = svars[i];
                    uint8_t scope;
                    size_t size;

                    if (svar == NULL || (size = svar->dtsv_size) == 0)
                              continue;

                    scope = svar->dtsv_var.dtdv_scope;

                    /*
                     * We verify that our size is valid in the spirit of providing
                     * defense in depth:  we want to prevent attackers from using
                     * DTrace to escalate an orthogonal kernel heap corruption bug
                     * into the ability to store to arbitrary locations in memory.
                     */
                    VERIFY((scope == DIFV_SCOPE_GLOBAL && size <= maxglobalsize) ||
                        (scope == DIFV_SCOPE_LOCAL && size <= maxlocalsize));

                    if (DTRACE_INRANGE(addr, sz, svar->dtsv_data,
                        svar->dtsv_size)) {
                              DTRACE_RANGE_REMAIN(remain, addr, svar->dtsv_data,
                                  svar->dtsv_size);
                              return (1);
                    }
          }

          return (0);
}

/*
 * Check to see if the address is within a memory region to which a store may
 * be issued.  This includes the DTrace scratch areas, and any DTrace variable
 * region.  The caller of dtrace_canstore() is responsible for performing any
 * alignment checks that are needed before stores are actually executed.
 */
static int
dtrace_canstore(uint64_t addr, size_t sz, dtrace_mstate_t *mstate,
    dtrace_vstate_t *vstate)
{
          return (dtrace_canstore_remains(addr, sz, NULL, mstate, vstate));
}

/*
 * Implementation of dtrace_canstore which communicates the upper bound of the
 * allowed memory region.
 */
static int
dtrace_canstore_remains(uint64_t addr, size_t sz, size_t *remain,
    dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
{
          /*
           * First, check to see if the address is in scratch space...
           */
          if (DTRACE_INRANGE(addr, sz, mstate->dtms_scratch_base,
              mstate->dtms_scratch_size)) {
                    DTRACE_RANGE_REMAIN(remain, addr, mstate->dtms_scratch_base,
                        mstate->dtms_scratch_size);
                    return (1);
          }

          /*
           * Now check to see if it's a dynamic variable.  This check will pick
           * up both thread-local variables and any global dynamically-allocated
           * variables.
           */
          if (DTRACE_INRANGE(addr, sz, (uintptr_t)vstate->dtvs_dynvars.dtds_base,
              vstate->dtvs_dynvars.dtds_size)) {
                    dtrace_dstate_t *dstate = &vstate->dtvs_dynvars;
                    uintptr_t base = (uintptr_t)dstate->dtds_base +
                        (dstate->dtds_hashsize * sizeof (dtrace_dynhash_t));
                    uintptr_t chunkoffs;
                    dtrace_dynvar_t *dvar;

                    /*
                     * Before we assume that we can store here, we need to make
                     * sure that it isn't in our metadata -- storing to our
                     * dynamic variable metadata would corrupt our state.  For
                     * the range to not include any dynamic variable metadata,
                     * it must:
                     *
                     *        (1) Start above the hash table that is at the base of
                     *        the dynamic variable space
                     *
                     *        (2) Have a starting chunk offset that is beyond the
                     *        dtrace_dynvar_t that is at the base of every chunk
                     *
                     *        (3) Not span a chunk boundary
                     *
                     *        (4) Not be in the tuple space of a dynamic variable
                     *
                     */
                    if (addr < base)
                              return (0);

                    chunkoffs = (addr - base) % dstate->dtds_chunksize;

                    if (chunkoffs < sizeof (dtrace_dynvar_t))
                              return (0);

                    if (chunkoffs + sz > dstate->dtds_chunksize)
                              return (0);

                    dvar = (dtrace_dynvar_t *)((uintptr_t)addr - chunkoffs);

                    if (dvar->dtdv_hashval == DTRACE_DYNHASH_FREE)
                              return (0);

                    if (chunkoffs < sizeof (dtrace_dynvar_t) +
                        ((dvar->dtdv_tuple.dtt_nkeys - 1) * sizeof (dtrace_key_t)))
                              return (0);

                    DTRACE_RANGE_REMAIN(remain, addr, dvar, dstate->dtds_chunksize);
                    return (1);
          }

          /*
           * Finally, check the static local and global variables.  These checks
           * take the longest, so we perform them last.
           */
          if (dtrace_canstore_statvar(addr, sz, remain,
              vstate->dtvs_locals, vstate->dtvs_nlocals))
                    return (1);

          if (dtrace_canstore_statvar(addr, sz, remain,
              vstate->dtvs_globals, vstate->dtvs_nglobals))
                    return (1);

          return (0);
}


/*
 * Convenience routine to check to see if the address is within a memory
 * region in which a load may be issued given the user's privilege level;
 * if not, it sets the appropriate error flags and loads 'addr' into the
 * illegal value slot.
 *
 * DTrace subroutines (DIF_SUBR_*) should use this helper to implement
 * appropriate memory access protection.
 */
static int
dtrace_canload(uint64_t addr, size_t sz, dtrace_mstate_t *mstate,
    dtrace_vstate_t *vstate)
{
          return (dtrace_canload_remains(addr, sz, NULL, mstate, vstate));
}

/*
 * Implementation of dtrace_canload which communicates the uppoer bound of the
 * allowed memory region.
 */
static int
dtrace_canload_remains(uint64_t addr, size_t sz, size_t *remain,
    dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
{
          volatile uintptr_t *illval = &cpu_core[curcpu_id].cpuc_dtrace_illval;
          file_t *fp;

          /*
           * If we hold the privilege to read from kernel memory, then
           * everything is readable.
           */
          if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0) {
                    DTRACE_RANGE_REMAIN(remain, addr, addr, sz);
                    return (1);
          }

          /*
           * You can obviously read that which you can store.
           */
          if (dtrace_canstore_remains(addr, sz, remain, mstate, vstate))
                    return (1);

          /*
           * We're allowed to read from our own string table.
           */
          if (DTRACE_INRANGE(addr, sz, mstate->dtms_difo->dtdo_strtab,
              mstate->dtms_difo->dtdo_strlen)) {
                    DTRACE_RANGE_REMAIN(remain, addr,
                        mstate->dtms_difo->dtdo_strtab,
                        mstate->dtms_difo->dtdo_strlen);
                    return (1);
          }

          if (vstate->dtvs_state != NULL &&
              dtrace_priv_proc(vstate->dtvs_state)) {
                    proc_t *p;

                    /*
                     * When we have privileges to the current process, there are
                     * several context-related kernel structures that are safe to
                     * read, even absent the privilege to read from kernel memory.
                     * These reads are safe because these structures contain only
                     * state that (1) we're permitted to read, (2) is harmless or
                     * (3) contains pointers to additional kernel state that we're
                     * not permitted to read (and as such, do not present an
                     * opportunity for privilege escalation).  Finally (and
                     * critically), because of the nature of their relation with
                     * the current thread context, the memory associated with these
                     * structures cannot change over the duration of probe context,
                     * and it is therefore impossible for this memory to be
                     * deallocated and reallocated as something else while it's
                     * being operated upon.
                     */
                    if (DTRACE_INRANGE(addr, sz, curthread, sizeof (kthread_t))) {
                              DTRACE_RANGE_REMAIN(remain, addr, curthread,
                                  sizeof (kthread_t));
                              return (1);
                    }

                    if ((p = curthread->t_procp) != NULL && DTRACE_INRANGE(addr,
                        sz, curthread->t_procp, sizeof (proc_t))) {
                              DTRACE_RANGE_REMAIN(remain, addr, curthread->t_procp,
                                  sizeof (proc_t));
                              return (1);
                    }

#ifndef __NetBSD__
                    if (curthread->t_cred != NULL && DTRACE_INRANGE(addr, sz,
                        curthread->t_cred, sizeof (cred_t))) {
                              DTRACE_RANGE_REMAIN(remain, addr, curthread->t_cred,
                                  sizeof (cred_t));
                              return (1);
                    }
#endif

#ifdef illumos
                    if (p != NULL && p->p_pidp != NULL && DTRACE_INRANGE(addr, sz,
                        &(p->p_pidp->pid_id), sizeof (pid_t))) {
                              DTRACE_RANGE_REMAIN(remain, addr, &(p->p_pidp->pid_id),
                                  sizeof (pid_t));
                              return (1);
                    }

                    if (curthread->t_cpu != NULL && DTRACE_INRANGE(addr, sz,
                        curthread->t_cpu, offsetof(cpu_t, cpu_pause_thread))) {
                              DTRACE_RANGE_REMAIN(remain, addr, curthread->t_cpu,
                                  offsetof(cpu_t, cpu_pause_thread));
                              return (1);
                    }
#endif
          }

          if ((fp = mstate->dtms_getf) != NULL) {
                    uintptr_t psz = sizeof (void *);
                    vnode_t *vp;
                    vnodeops_t *op;

                    /*
                     * When getf() returns a file_t, the enabling is implicitly
                     * granted the (transient) right to read the returned file_t
                     * as well as the v_path and v_op->vnop_name of the underlying
                     * vnode.  These accesses are allowed after a successful
                     * getf() because the members that they refer to cannot change
                     * once set -- and the barrier logic in the kernel's closef()
                     * path assures that the file_t and its referenced vode_t
                     * cannot themselves be stale (that is, it impossible for
                     * either dtms_getf itself or its f_vnode member to reference
                     * freed memory).
                     */
                    if (DTRACE_INRANGE(addr, sz, fp, sizeof (file_t))) {
                              DTRACE_RANGE_REMAIN(remain, addr, fp, sizeof (file_t));
                              return (1);
                    }

                    if ((vp = fp->f_vnode) != NULL) {
                              size_t slen;
#ifdef illumos
                              if (DTRACE_INRANGE(addr, sz, &vp->v_path, psz)) {
                                        DTRACE_RANGE_REMAIN(remain, addr, &vp->v_path,
                                            psz);
                                        return (1);
                              }
                              slen = strlen(vp->v_path) + 1;
                              if (DTRACE_INRANGE(addr, sz, vp->v_path, slen)) {
                                        DTRACE_RANGE_REMAIN(remain, addr, vp->v_path,
                                            slen);
                                        return (1);
                              }
#endif

                              if (DTRACE_INRANGE(addr, sz, &vp->v_op, psz)) {
                                        DTRACE_RANGE_REMAIN(remain, addr, &vp->v_op,
                                            psz);
                                        return (1);
                              }

#ifdef illumos
                              if ((op = vp->v_op) != NULL &&
                                  DTRACE_INRANGE(addr, sz, &op->vnop_name, psz)) {
                                        DTRACE_RANGE_REMAIN(remain, addr,
                                            &op->vnop_name, psz);
                                        return (1);
                              }

                              if (op != NULL && op->vnop_name != NULL &&
                                  DTRACE_INRANGE(addr, sz, op->vnop_name,
                                  (slen = strlen(op->vnop_name) + 1))) {
                                        DTRACE_RANGE_REMAIN(remain, addr,
                                            op->vnop_name, slen);
                                        return (1);
                              }
#endif
                    }
          }

          DTRACE_CPUFLAG_SET(CPU_DTRACE_KPRIV);
          *illval = addr;
          return (0);
}

/*
 * Convenience routine to check to see if a given string is within a memory
 * region in which a load may be issued given the user's privilege level;
 * this exists so that we don't need to issue unnecessary dtrace_strlen()
 * calls in the event that the user has all privileges.
 */
static int
dtrace_strcanload(uint64_t addr, size_t sz, size_t *remain,
    dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
{
          size_t rsize;

          /*
           * If we hold the privilege to read from kernel memory, then
           * everything is readable.
           */

          if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0) {
                    DTRACE_RANGE_REMAIN(remain, addr, addr, sz);
                    return (1);
          }

          /*
           * Even if the caller is uninterested in querying the remaining valid
           * range, it is required to ensure that the access is allowed.
           */
          if (remain == NULL) {
                    remain = &rsize;
          }
          if (dtrace_canload_remains(addr, 0, remain, mstate, vstate)) {
                    size_t strsz;
                    /*
                     * Perform the strlen after determining the length of the
                     * memory region which is accessible.  This prevents timing
                     * information from being used to find NULs in memory which is
                     * not accessible to the caller.
                     */
                    strsz = 1 + dtrace_strlen((char *)(uintptr_t)addr,
                        MIN(sz, *remain));
                    if (strsz <= *remain) {
                              return (1);
                    }
          }

          return (0);
}

/*
 * Convenience routine to check to see if a given variable is within a memory
 * region in which a load may be issued given the user's privilege level.
 */
static int
dtrace_vcanload(void *src, dtrace_diftype_t *type, size_t *remain,
    dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
{
          size_t sz;
          ASSERT(type->dtdt_flags & DIF_TF_BYREF);

          /*
           * Calculate the max size before performing any checks since even
           * DTRACE_ACCESS_KERNEL-credentialed callers expect that this function
           * return the max length via 'remain'.
           */
          if (type->dtdt_kind == DIF_TYPE_STRING) {
                    dtrace_state_t *state = vstate->dtvs_state;

                    if (state != NULL) {
                              sz = state->dts_options[DTRACEOPT_STRSIZE];
                    } else {
                              /*
                               * In helper context, we have a NULL state; fall back
                               * to using the system-wide default for the string size
                               * in this case.
                               */
                              sz = dtrace_strsize_default;
                    }
          } else {
                    sz = type->dtdt_size;
          }

          /*
           * If we hold the privilege to read from kernel memory, then
           * everything is readable.
           */
          if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0) {
                    DTRACE_RANGE_REMAIN(remain, (uintptr_t)src, src, sz);
                    return (1);
          }

          if (type->dtdt_kind == DIF_TYPE_STRING) {
                    return (dtrace_strcanload((uintptr_t)src, sz, remain, mstate,
                        vstate));
          }
          return (dtrace_canload_remains((uintptr_t)src, sz, remain, mstate,
              vstate));
}

/*
 * Convert a string to a signed integer using safe loads.
 *
 * NOTE: This function uses various macros from strtolctype.h to manipulate
 * digit values, etc -- these have all been checked to ensure they make
 * no additional function calls.
 */
static int64_t
dtrace_strtoll(char *input, int base, size_t limit)
{
          uintptr_t pos = (uintptr_t)input;
          int64_t val = 0;
          int x;
          boolean_t neg = B_FALSE;
          char c, cc, ccc;
          uintptr_t end = pos + limit;

          /*
           * Consume any whitespace preceding digits.
           */
          while ((c = dtrace_load8(pos)) == ' ' || c == '\t')
                    pos++;

          /*
           * Handle an explicit sign if one is present.
           */
          if (c == '-' || c == '+') {
                    if (c == '-')
                              neg = B_TRUE;
                    c = dtrace_load8(++pos);
          }

          /*
           * Check for an explicit hexadecimal prefix ("0x" or "0X") and skip it
           * if present.
           */
          if (base == 16 && c == '0' && ((cc = dtrace_load8(pos + 1)) == 'x' ||
              cc == 'X') && isxdigit(ccc = dtrace_load8(pos + 2))) {
                    pos += 2;
                    c = ccc;
          }

          /*
           * Read in contiguous digits until the first non-digit character.
           */
          for (; pos < end && c != '\0' && lisalnum(c) && (x = DIGIT(c)) < base;
              c = dtrace_load8(++pos))
                    val = val * base + x;

          return (neg ? -val : val);
}

/*
 * Compare two strings using safe loads.
 */
static int
dtrace_strncmp(char *s1, char *s2, size_t limit)
{
          uint8_t c1, c2;
          volatile uint16_t *flags;

          if (s1 == s2 || limit == 0)
                    return (0);

          flags = (volatile uint16_t *)&cpu_core[curcpu_id].cpuc_dtrace_flags;

          do {
                    if (s1 == NULL) {
                              c1 = '\0';
                    } else {
                              c1 = dtrace_load8((uintptr_t)s1++);
                    }

                    if (s2 == NULL) {
                              c2 = '\0';
                    } else {
                              c2 = dtrace_load8((uintptr_t)s2++);
                    }

                    if (c1 != c2)
                              return (c1 - c2);
          } while (--limit && c1 != '\0' && !(*flags & CPU_DTRACE_FAULT));

          return (0);
}

/*
 * Compute strlen(s) for a string using safe memory accesses.  The additional
 * len parameter is used to specify a maximum length to ensure completion.
 */
static size_t
dtrace_strlen(const char *s, size_t lim)
{
          uint_t len;

          for (len = 0; len != lim; len++) {
                    if (dtrace_load8((uintptr_t)s++) == '\0')
                              break;
          }

          return (len);
}

/*
 * Check if an address falls within a toxic region.
 */
static int
dtrace_istoxic(uintptr_t kaddr, size_t size)
{
          uintptr_t taddr, tsize;
          int i;

          for (i = 0; i < dtrace_toxranges; i++) {
                    taddr = dtrace_toxrange[i].dtt_base;
                    tsize = dtrace_toxrange[i].dtt_limit - taddr;

                    if (kaddr - taddr < tsize) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                              cpu_core[curcpu_id].cpuc_dtrace_illval = kaddr;
                              return (1);
                    }

                    if (taddr - kaddr < size) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                              cpu_core[curcpu_id].cpuc_dtrace_illval = taddr;
                              return (1);
                    }
          }

          return (0);
}

/*
 * Copy src to dst using safe memory accesses.  The src is assumed to be unsafe
 * memory specified by the DIF program.  The dst is assumed to be safe memory
 * that we can store to directly because it is managed by DTrace.  As with
 * standard bcopy, overlapping copies are handled properly.
 */
static void
dtrace_bcopy(const void *src, void *dst, size_t len)
{
          if (len != 0) {
                    uint8_t *s1 = dst;
                    const uint8_t *s2 = src;

                    if (s1 <= s2) {
                              do {
                                        *s1++ = dtrace_load8((uintptr_t)s2++);
                              } while (--len != 0);
                    } else {
                              s2 += len;
                              s1 += len;

                              do {
                                        *--s1 = dtrace_load8((uintptr_t)--s2);
                              } while (--len != 0);
                    }
          }
}

/*
 * Copy src to dst using safe memory accesses, up to either the specified
 * length, or the point that a nul byte is encountered.  The src is assumed to
 * be unsafe memory specified by the DIF program.  The dst is assumed to be
 * safe memory that we can store to directly because it is managed by DTrace.
 * Unlike dtrace_bcopy(), overlapping regions are not handled.
 */
static void
dtrace_strcpy(const void *src, void *dst, size_t len)
{
          if (len != 0) {
                    uint8_t *s1 = dst, c;
                    const uint8_t *s2 = src;

                    do {
                              *s1++ = c = dtrace_load8((uintptr_t)s2++);
                    } while (--len != 0 && c != '\0');
          }
}

/*
 * Copy src to dst, deriving the size and type from the specified (BYREF)
 * variable type.  The src is assumed to be unsafe memory specified by the DIF
 * program.  The dst is assumed to be DTrace variable memory that is of the
 * specified type; we assume that we can store to directly.
 */
static void
dtrace_vcopy(void *src, void *dst, dtrace_diftype_t *type, size_t limit)
{
          ASSERT(type->dtdt_flags & DIF_TF_BYREF);

          if (type->dtdt_kind == DIF_TYPE_STRING) {
                    dtrace_strcpy(src, dst, MIN(type->dtdt_size, limit));
          } else {
                    dtrace_bcopy(src, dst, MIN(type->dtdt_size, limit));
          }
}

/*
 * Compare s1 to s2 using safe memory accesses.  The s1 data is assumed to be
 * unsafe memory specified by the DIF program.  The s2 data is assumed to be
 * safe memory that we can access directly because it is managed by DTrace.
 */
static int
dtrace_bcmp(const void *s1, const void *s2, size_t len)
{
          volatile uint16_t *flags;

          flags = (volatile uint16_t *)&cpu_core[curcpu_id].cpuc_dtrace_flags;

          if (s1 == s2)
                    return (0);

          if (s1 == NULL || s2 == NULL)
                    return (1);

          if (s1 != s2 && len != 0) {
                    const uint8_t *ps1 = s1;
                    const uint8_t *ps2 = s2;

                    do {
                              if (dtrace_load8((uintptr_t)ps1++) != *ps2++)
                                        return (1);
                    } while (--len != 0 && !(*flags & CPU_DTRACE_FAULT));
          }
          return (0);
}

/*
 * Zero the specified region using a simple byte-by-byte loop.  Note that this
 * is for safe DTrace-managed memory only.
 */
static void
dtrace_bzero(void *dst, size_t len)
{
          uchar_t *cp;

          for (cp = dst; len != 0; len--)
                    *cp++ = 0;
}

static void
dtrace_add_128(uint64_t *addend1, uint64_t *addend2, uint64_t *sum)
{
          uint64_t result[2];

          result[0] = addend1[0] + addend2[0];
          result[1] = addend1[1] + addend2[1] +
              (result[0] < addend1[0] || result[0] < addend2[0] ? 1 : 0);

          sum[0] = result[0];
          sum[1] = result[1];
}

/*
 * Shift the 128-bit value in a by b. If b is positive, shift left.
 * If b is negative, shift right.
 */
static void
dtrace_shift_128(uint64_t *a, int b)
{
          uint64_t mask;

          if (b == 0)
                    return;

          if (b < 0) {
                    b = -b;
                    if (b >= 64) {
                              a[0] = a[1] >> (b - 64);
                              a[1] = 0;
                    } else {
                              a[0] >>= b;
                              mask = 1LL << (64 - b);
                              mask -= 1;
                              a[0] |= ((a[1] & mask) << (64 - b));
                              a[1] >>= b;
                    }
          } else {
                    if (b >= 64) {
                              a[1] = a[0] << (b - 64);
                              a[0] = 0;
                    } else {
                              a[1] <<= b;
                              mask = a[0] >> (64 - b);
                              a[1] |= mask;
                              a[0] <<= b;
                    }
          }
}

/*
 * The basic idea is to break the 2 64-bit values into 4 32-bit values,
 * use native multiplication on those, and then re-combine into the
 * resulting 128-bit value.
 *
 * (hi1 << 32 + lo1) * (hi2 << 32 + lo2) =
 *     hi1 * hi2 << 64 +
 *     hi1 * lo2 << 32 +
 *     hi2 * lo1 << 32 +
 *     lo1 * lo2
 */
static void
dtrace_multiply_128(uint64_t factor1, uint64_t factor2, uint64_t *product)
{
          uint64_t hi1, hi2, lo1, lo2;
          uint64_t tmp[2];

          hi1 = factor1 >> 32;
          hi2 = factor2 >> 32;

          lo1 = factor1 & DT_MASK_LO;
          lo2 = factor2 & DT_MASK_LO;

          product[0] = lo1 * lo2;
          product[1] = hi1 * hi2;

          tmp[0] = hi1 * lo2;
          tmp[1] = 0;
          dtrace_shift_128(tmp, 32);
          dtrace_add_128(product, tmp, product);

          tmp[0] = hi2 * lo1;
          tmp[1] = 0;
          dtrace_shift_128(tmp, 32);
          dtrace_add_128(product, tmp, product);
}

/*
 * This privilege check should be used by actions and subroutines to
 * verify that the user credentials of the process that enabled the
 * invoking ECB match the target credentials
 */
static int
dtrace_priv_proc_common_user(dtrace_state_t *state)
{
          cred_t *cr, *s_cr = state->dts_cred.dcr_cred;

          /*
           * We should always have a non-NULL state cred here, since if cred
           * is null (anonymous tracing), we fast-path bypass this routine.
           */
          ASSERT(s_cr != NULL);

#ifdef __NetBSD__
          if ((cr = CRED()) != NULL) {
              uid_t uid;
              gid_t gid;

              uid = kauth_cred_getuid(s_cr);
              gid = kauth_cred_getgid(s_cr);

                    if (uid == kauth_cred_getuid(cr) &&
                        uid == kauth_cred_geteuid(cr) &&
                        uid == kauth_cred_getsvuid(cr) &&
                        gid == kauth_cred_getgid(cr) &&
                        gid == kauth_cred_getegid(cr) &&
                        gid == kauth_cred_getsvgid(cr))
                              return 1;
          }
#else
          if ((cr = CRED()) != NULL &&
              s_cr->cr_uid == cr->cr_uid &&
              s_cr->cr_uid == cr->cr_ruid &&
              s_cr->cr_uid == cr->cr_suid &&
              s_cr->cr_gid == cr->cr_gid &&
              s_cr->cr_gid == cr->cr_rgid &&
              s_cr->cr_gid == cr->cr_sgid)
                    return (1);
#endif

          return (0);
}

/*
 * This privilege check should be used by actions and subroutines to
 * verify that the zone of the process that enabled the invoking ECB
 * matches the target credentials
 */
static int
dtrace_priv_proc_common_zone(dtrace_state_t *state)
{
#ifdef illumos
          cred_t *cr, *s_cr = state->dts_cred.dcr_cred;

          /*
           * We should always have a non-NULL state cred here, since if cred
           * is null (anonymous tracing), we fast-path bypass this routine.
           */
          ASSERT(s_cr != NULL);

          if ((cr = CRED()) != NULL && s_cr->cr_zone == cr->cr_zone)
              s_cr->cr_zone == cr->cr_zone)
                    return (1);

          return (0);
#else
          return (1);
#endif
}

/*
 * This privilege check should be used by actions and subroutines to
 * verify that the process has not setuid or changed credentials.
 */
static int
dtrace_priv_proc_common_nocd(void)
{
          proc_t *proc;

          if ((proc = ttoproc(curthread)) != NULL &&
              !(proc->p_flag & SNOCD))
                    return (1);

          return (0);
}

static int
dtrace_priv_proc_destructive(dtrace_state_t *state)
{
          int action = state->dts_cred.dcr_action;

          if (((action & DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE) == 0) &&
              dtrace_priv_proc_common_zone(state) == 0)
                    goto bad;

          if (((action & DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER) == 0) &&
              dtrace_priv_proc_common_user(state) == 0)
                    goto bad;

          if (((action & DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG) == 0) &&
              dtrace_priv_proc_common_nocd() == 0)
                    goto bad;

          return (1);

bad:
          cpu_core[curcpu_id].cpuc_dtrace_flags |= CPU_DTRACE_UPRIV;

          return (0);
}

static int
dtrace_priv_proc_control(dtrace_state_t *state)
{
          if (state->dts_cred.dcr_action & DTRACE_CRA_PROC_CONTROL)
                    return (1);

          if (dtrace_priv_proc_common_zone(state) &&
              dtrace_priv_proc_common_user(state) &&
              dtrace_priv_proc_common_nocd())
                    return (1);

          cpu_core[curcpu_id].cpuc_dtrace_flags |= CPU_DTRACE_UPRIV;

          return (0);
}

static int
dtrace_priv_proc(dtrace_state_t *state)
{
          if (state->dts_cred.dcr_action & DTRACE_CRA_PROC)
                    return (1);

          cpu_core[curcpu_id].cpuc_dtrace_flags |= CPU_DTRACE_UPRIV;

          return (0);
}

static int
dtrace_priv_kernel(dtrace_state_t *state)
{
          if (state->dts_cred.dcr_action & DTRACE_CRA_KERNEL)
                    return (1);

          cpu_core[curcpu_id].cpuc_dtrace_flags |= CPU_DTRACE_KPRIV;

          return (0);
}

static int
dtrace_priv_kernel_destructive(dtrace_state_t *state)
{
          if (state->dts_cred.dcr_action & DTRACE_CRA_KERNEL_DESTRUCTIVE)
                    return (1);

          cpu_core[curcpu_id].cpuc_dtrace_flags |= CPU_DTRACE_KPRIV;

          return (0);
}

/*
 * Determine if the dte_cond of the specified ECB allows for processing of
 * the current probe to continue.  Note that this routine may allow continued
 * processing, but with access(es) stripped from the mstate's dtms_access
 * field.
 */
static int
dtrace_priv_probe(dtrace_state_t *state, dtrace_mstate_t *mstate,
    dtrace_ecb_t *ecb)
{
          dtrace_probe_t *probe = ecb->dte_probe;
          dtrace_provider_t *prov = probe->dtpr_provider;
          dtrace_pops_t *pops = &prov->dtpv_pops;
          int mode = DTRACE_MODE_NOPRIV_DROP;

          ASSERT(ecb->dte_cond);

#ifdef illumos
          if (pops->dtps_mode != NULL) {
                    mode = pops->dtps_mode(prov->dtpv_arg,
                        probe->dtpr_id, probe->dtpr_arg);

                    ASSERT((mode & DTRACE_MODE_USER) ||
                        (mode & DTRACE_MODE_KERNEL));
                    ASSERT((mode & DTRACE_MODE_NOPRIV_RESTRICT) ||
                        (mode & DTRACE_MODE_NOPRIV_DROP));
          }

          /*
           * If the dte_cond bits indicate that this consumer is only allowed to
           * see user-mode firings of this probe, call the provider's dtps_mode()
           * entry point to check that the probe was fired while in a user
           * context.  If that's not the case, use the policy specified by the
           * provider to determine if we drop the probe or merely restrict
           * operation.
           */
          if (ecb->dte_cond & DTRACE_COND_USERMODE) {
                    ASSERT(mode != DTRACE_MODE_NOPRIV_DROP);

                    if (!(mode & DTRACE_MODE_USER)) {
                              if (mode & DTRACE_MODE_NOPRIV_DROP)
                                        return (0);

                              mstate->dtms_access &= ~DTRACE_ACCESS_ARGS;
                    }
          }
#endif

          /*
           * This is more subtle than it looks. We have to be absolutely certain
           * that CRED() isn't going to change out from under us so it's only
           * legit to examine that structure if we're in constrained situations.
           * Currently, the only times we'll this check is if a non-super-user
           * has enabled the profile or syscall providers -- providers that
           * allow visibility of all processes. For the profile case, the check
           * above will ensure that we're examining a user context.
           */
          if (ecb->dte_cond & DTRACE_COND_OWNER) {
                    cred_t *cr;
                    cred_t *s_cr = state->dts_cred.dcr_cred;
                    proc_t *proc;

                    ASSERT(s_cr != NULL);

#ifdef __NetBSD__
                    uid_t uid = kauth_cred_getuid(s_cr);
                    gid_t gid = kauth_cred_getgid(s_cr);

                    if ((cr = CRED()) == NULL ||
                        uid != kauth_cred_geteuid(cr) ||
                        uid != kauth_cred_getuid(cr) ||
                        uid != kauth_cred_getsvuid(cr) ||
                        gid != kauth_cred_getegid(cr) ||
                        gid != kauth_cred_getgid(cr) ||
                        gid != kauth_cred_getsvgid(cr) ||
                        (proc = ttoproc(curthread)) == NULL ||
                        (proc->p_flag & SNOCD)) {
                              if (mode & DTRACE_MODE_NOPRIV_DROP)
                                        return (0);
                    }
#else /* __NetBSD__ */
                    if ((cr = CRED()) == NULL ||
                        s_cr->cr_uid != cr->cr_uid ||
                        s_cr->cr_uid != cr->cr_ruid ||
                        s_cr->cr_uid != cr->cr_suid ||
                        s_cr->cr_gid != cr->cr_gid ||
                        s_cr->cr_gid != cr->cr_rgid ||
                        s_cr->cr_gid != cr->cr_sgid ||
                        (proc = ttoproc(curthread)) == NULL ||
                        (proc->p_flag & SNOCD)) {
                              if (mode & DTRACE_MODE_NOPRIV_DROP)
                                        return (0);

#ifdef illumos
                              mstate->dtms_access &= ~DTRACE_ACCESS_PROC;
#endif
                    }
#endif /* __NetBSD__ */
          }

#ifdef illumos
          /*
           * If our dte_cond is set to DTRACE_COND_ZONEOWNER and we are not
           * in our zone, check to see if our mode policy is to restrict rather
           * than to drop; if to restrict, strip away both DTRACE_ACCESS_PROC
           * and DTRACE_ACCESS_ARGS
           */
          if (ecb->dte_cond & DTRACE_COND_ZONEOWNER) {
                    cred_t *cr;
                    cred_t *s_cr = state->dts_cred.dcr_cred;

                    ASSERT(s_cr != NULL);

                    if ((cr = CRED()) == NULL ||
                        s_cr->cr_zone->zone_id != cr->cr_zone->zone_id) {
                              if (mode & DTRACE_MODE_NOPRIV_DROP)
                                        return (0);

                              mstate->dtms_access &=
                                  ~(DTRACE_ACCESS_PROC | DTRACE_ACCESS_ARGS);
                    }
          }
#endif

          return (1);
}

/*
 * Note:  not called from probe context.  This function is called
 * asynchronously (and at a regular interval) from outside of probe context to
 * clean the dirty dynamic variable lists on all CPUs.  Dynamic variable
 * cleaning is explained in detail in <sys/dtrace_impl.h>.
 */
void
dtrace_dynvar_clean(dtrace_dstate_t *dstate)
{
          dtrace_dynvar_t *dirty;
          dtrace_dstate_percpu_t *dcpu;
          dtrace_dynvar_t **rinsep;
          int i, j, work = 0;

          for (i = 0; i < NCPU; i++) {
                    dcpu = &dstate->dtds_percpu[i];

                    rinsep = &dcpu->dtdsc_rinsing;

                    /*
                     * If the dirty list is NULL, there is no dirty work to do.
                     */
                    if (dcpu->dtdsc_dirty == NULL)
                              continue;

                    if (dcpu->dtdsc_rinsing != NULL) {
                              /*
                               * If the rinsing list is non-NULL, then it is because
                               * this CPU was selected to accept another CPU's
                               * dirty list -- and since that time, dirty buffers
                               * have accumulated.  This is a highly unlikely
                               * condition, but we choose to ignore the dirty
                               * buffers -- they'll be picked up a future cleanse.
                               */
                              continue;
                    }

                    if (dcpu->dtdsc_clean != NULL) {
                              /*
                               * If the clean list is non-NULL, then we're in a
                               * situation where a CPU has done deallocations (we
                               * have a non-NULL dirty list) but no allocations (we
                               * also have a non-NULL clean list).  We can't simply
                               * move the dirty list into the clean list on this
                               * CPU, yet we also don't want to allow this condition
                               * to persist, lest a short clean list prevent a
                               * massive dirty list from being cleaned (which in
                               * turn could lead to otherwise avoidable dynamic
                               * drops).  To deal with this, we look for some CPU
                               * with a NULL clean list, NULL dirty list, and NULL
                               * rinsing list -- and then we borrow this CPU to
                               * rinse our dirty list.
                               */
                              for (j = 0; j < NCPU; j++) {
                                        dtrace_dstate_percpu_t *rinser;

                                        rinser = &dstate->dtds_percpu[j];

                                        if (rinser->dtdsc_rinsing != NULL)
                                                  continue;

                                        if (rinser->dtdsc_dirty != NULL)
                                                  continue;

                                        if (rinser->dtdsc_clean != NULL)
                                                  continue;

                                        rinsep = &rinser->dtdsc_rinsing;
                                        break;
                              }

                              if (j == NCPU) {
                                        /*
                                         * We were unable to find another CPU that
                                         * could accept this dirty list -- we are
                                         * therefore unable to clean it now.
                                         */
                                        dtrace_dynvar_failclean++;
                                        continue;
                              }
                    }

                    work = 1;

                    /*
                     * Atomically move the dirty list aside.
                     */
                    do {
                              dirty = dcpu->dtdsc_dirty;

                              /*
                               * Before we zap the dirty list, set the rinsing list.
                               * (This allows for a potential assertion in
                               * dtrace_dynvar():  if a free dynamic variable appears
                               * on a hash chain, either the dirty list or the
                               * rinsing list for some CPU must be non-NULL.)
                               */
                              *rinsep = dirty;
                              dtrace_membar_producer();
                    } while (dtrace_casptr(&dcpu->dtdsc_dirty,
                        dirty, NULL) != dirty);
          }

          if (!work) {
                    /*
                     * We have no work to do; we can simply return.
                     */
                    return;
          }

          dtrace_sync();

          for (i = 0; i < NCPU; i++) {
                    dcpu = &dstate->dtds_percpu[i];

                    if (dcpu->dtdsc_rinsing == NULL)
                              continue;

                    /*
                     * We are now guaranteed that no hash chain contains a pointer
                     * into this dirty list; we can make it clean.
                     */
                    ASSERT(dcpu->dtdsc_clean == NULL);
                    dcpu->dtdsc_clean = dcpu->dtdsc_rinsing;
                    dcpu->dtdsc_rinsing = NULL;
          }

          /*
           * Before we actually set the state to be DTRACE_DSTATE_CLEAN, make
           * sure that all CPUs have seen all of the dtdsc_clean pointers.
           * This prevents a race whereby a CPU incorrectly decides that
           * the state should be something other than DTRACE_DSTATE_CLEAN
           * after dtrace_dynvar_clean() has completed.
           */
          dtrace_sync();

          dstate->dtds_state = DTRACE_DSTATE_CLEAN;
}

/*
 * Depending on the value of the op parameter, this function looks-up,
 * allocates or deallocates an arbitrarily-keyed dynamic variable.  If an
 * allocation is requested, this function will return a pointer to a
 * dtrace_dynvar_t corresponding to the allocated variable -- or NULL if no
 * variable can be allocated.  If NULL is returned, the appropriate counter
 * will be incremented.
 */
dtrace_dynvar_t *
dtrace_dynvar(dtrace_dstate_t *dstate, uint_t nkeys,
    dtrace_key_t *key, size_t dsize, dtrace_dynvar_op_t op,
    dtrace_mstate_t *mstate, dtrace_vstate_t *vstate)
{
          uint64_t hashval = DTRACE_DYNHASH_VALID;
          dtrace_dynhash_t *hash = dstate->dtds_hash;
          dtrace_dynvar_t *free, *new_free, *next, *dvar, *start, *prev = NULL;
          processorid_t me = curcpu_id, cpu = me;
          dtrace_dstate_percpu_t *dcpu = &dstate->dtds_percpu[me];
          size_t bucket, ksize;
          size_t chunksize = dstate->dtds_chunksize;
          uintptr_t kdata, lock, nstate;
          uint_t i;

          ASSERT(nkeys != 0);

          /*
           * Hash the key.  As with aggregations, we use Jenkins' "One-at-a-time"
           * algorithm.  For the by-value portions, we perform the algorithm in
           * 16-bit chunks (as opposed to 8-bit chunks).  This speeds things up a
           * bit, and seems to have only a minute effect on distribution.  For
           * the by-reference data, we perform "One-at-a-time" iterating (safely)
           * over each referenced byte.  It's painful to do this, but it's much
           * better than pathological hash distribution.  The efficacy of the
           * hashing algorithm (and a comparison with other algorithms) may be
           * found by running the ::dtrace_dynstat MDB dcmd.
           */
          for (i = 0; i < nkeys; i++) {
                    if (key[i].dttk_size == 0) {
                              uint64_t val = key[i].dttk_value;

                              hashval += (val >> 48) & 0xffff;
                              hashval += (hashval << 10);
                              hashval ^= (hashval >> 6);

                              hashval += (val >> 32) & 0xffff;
                              hashval += (hashval << 10);
                              hashval ^= (hashval >> 6);

                              hashval += (val >> 16) & 0xffff;
                              hashval += (hashval << 10);
                              hashval ^= (hashval >> 6);

                              hashval += val & 0xffff;
                              hashval += (hashval << 10);
                              hashval ^= (hashval >> 6);
                    } else {
                              /*
                               * This is incredibly painful, but it beats the hell
                               * out of the alternative.
                               */
                              uint64_t j, size = key[i].dttk_size;
                              uintptr_t base = (uintptr_t)key[i].dttk_value;

                              if (!dtrace_canload(base, size, mstate, vstate))
                                        break;

                              for (j = 0; j < size; j++) {
                                        hashval += dtrace_load8(base + j);
                                        hashval += (hashval << 10);
                                        hashval ^= (hashval >> 6);
                              }
                    }
          }

          if (DTRACE_CPUFLAG_ISSET(CPU_DTRACE_FAULT))
                    return (NULL);

          hashval += (hashval << 3);
          hashval ^= (hashval >> 11);
          hashval += (hashval << 15);

          /*
           * There is a remote chance (ideally, 1 in 2^31) that our hashval
           * comes out to be one of our two sentinel hash values.  If this
           * actually happens, we set the hashval to be a value known to be a
           * non-sentinel value.
           */
          if (hashval == DTRACE_DYNHASH_FREE || hashval == DTRACE_DYNHASH_SINK)
                    hashval = DTRACE_DYNHASH_VALID;

          /*
           * Yes, it's painful to do a divide here.  If the cycle count becomes
           * important here, tricks can be pulled to reduce it.  (However, it's
           * critical that hash collisions be kept to an absolute minimum;
           * they're much more painful than a divide.)  It's better to have a
           * solution that generates few collisions and still keeps things
           * relatively simple.
           */
          bucket = hashval % dstate->dtds_hashsize;

          if (op == DTRACE_DYNVAR_DEALLOC) {
                    volatile uintptr_t *lockp = &hash[bucket].dtdh_lock;

                    for (;;) {
                              while ((lock = *lockp) & 1)
                                        continue;

                              if (dtrace_casptr((volatile void *)lockp,
                                  (volatile void *)lock, (volatile void *)(lock + 1)) == (void *)lock)
                                        break;
                    }

                    dtrace_membar_producer();
          }

top:
          prev = NULL;
          lock = hash[bucket].dtdh_lock;

          dtrace_membar_consumer();

          start = hash[bucket].dtdh_chain;
          ASSERT(start != NULL && (start->dtdv_hashval == DTRACE_DYNHASH_SINK ||
              start->dtdv_hashval != DTRACE_DYNHASH_FREE ||
              op != DTRACE_DYNVAR_DEALLOC));

          for (dvar = start; dvar != NULL; dvar = dvar->dtdv_next) {
                    dtrace_tuple_t *dtuple = &dvar->dtdv_tuple;
                    dtrace_key_t *dkey = &dtuple->dtt_key[0];

                    if (dvar->dtdv_hashval != hashval) {
                              if (dvar->dtdv_hashval == DTRACE_DYNHASH_SINK) {
                                        /*
                                         * We've reached the sink, and therefore the
                                         * end of the hash chain; we can kick out of
                                         * the loop knowing that we have seen a valid
                                         * snapshot of state.
                                         */
                                        ASSERT(dvar->dtdv_next == NULL);
                                        ASSERT(dvar == &dtrace_dynhash_sink);
                                        break;
                              }

                              if (dvar->dtdv_hashval == DTRACE_DYNHASH_FREE) {
                                        /*
                                         * We've gone off the rails:  somewhere along
                                         * the line, one of the members of this hash
                                         * chain was deleted.  Note that we could also
                                         * detect this by simply letting this loop run
                                         * to completion, as we would eventually hit
                                         * the end of the dirty list.  However, we
                                         * want to avoid running the length of the
                                         * dirty list unnecessarily (it might be quite
                                         * long), so we catch this as early as
                                         * possible by detecting the hash marker.  In
                                         * this case, we simply set dvar to NULL and
                                         * break; the conditional after the loop will
                                         * send us back to top.
                                         */
                                        dvar = NULL;
                                        break;
                              }

                              goto next;
                    }

                    if (dtuple->dtt_nkeys != nkeys)
                              goto next;

                    for (i = 0; i < nkeys; i++, dkey++) {
                              if (dkey->dttk_size != key[i].dttk_size)
                                        goto next; /* size or type mismatch */

                              if (dkey->dttk_size != 0) {
                                        if (dtrace_bcmp(
                                            (void *)(uintptr_t)key[i].dttk_value,
                                            (void *)(uintptr_t)dkey->dttk_value,
                                            dkey->dttk_size))
                                                  goto next;
                              } else {
                                        if (dkey->dttk_value != key[i].dttk_value)
                                                  goto next;
                              }
                    }

                    if (op != DTRACE_DYNVAR_DEALLOC)
                              return (dvar);

                    ASSERT(dvar->dtdv_next == NULL ||
                        dvar->dtdv_next->dtdv_hashval != DTRACE_DYNHASH_FREE);

                    if (prev != NULL) {
                              ASSERT(hash[bucket].dtdh_chain != dvar);
                              ASSERT(start != dvar);
                              ASSERT(prev->dtdv_next == dvar);
                              prev->dtdv_next = dvar->dtdv_next;
                    } else {
                              if (dtrace_casptr(&hash[bucket].dtdh_chain,
                                  start, dvar->dtdv_next) != start) {
                                        /*
                                         * We have failed to atomically swing the
                                         * hash table head pointer, presumably because
                                         * of a conflicting allocation on another CPU.
                                         * We need to reread the hash chain and try
                                         * again.
                                         */
                                        goto top;
                              }
                    }

                    dtrace_membar_producer();

                    /*
                     * Now set the hash value to indicate that it's free.
                     */
                    ASSERT(hash[bucket].dtdh_chain != dvar);
                    dvar->dtdv_hashval = DTRACE_DYNHASH_FREE;

                    dtrace_membar_producer();

                    /*
                     * Set the next pointer to point at the dirty list, and
                     * atomically swing the dirty pointer to the newly freed dvar.
                     */
                    do {
                              next = dcpu->dtdsc_dirty;
                              dvar->dtdv_next = next;
                    } while (dtrace_casptr(&dcpu->dtdsc_dirty, next, dvar) != next);

                    /*
                     * Finally, unlock this hash bucket.
                     */
                    ASSERT(hash[bucket].dtdh_lock == lock);
                    ASSERT(lock & 1);
                    hash[bucket].dtdh_lock++;

                    return (NULL);
next:
                    prev = dvar;
                    continue;
          }

          if (dvar == NULL) {
                    /*
                     * If dvar is NULL, it is because we went off the rails:
                     * one of the elements that we traversed in the hash chain
                     * was deleted while we were traversing it.  In this case,
                     * we assert that we aren't doing a dealloc (deallocs lock
                     * the hash bucket to prevent themselves from racing with
                     * one another), and retry the hash chain traversal.
                     */
                    ASSERT(op != DTRACE_DYNVAR_DEALLOC);
                    goto top;
          }

          if (op != DTRACE_DYNVAR_ALLOC) {
                    /*
                     * If we are not to allocate a new variable, we want to
                     * return NULL now.  Before we return, check that the value
                     * of the lock word hasn't changed.  If it has, we may have
                     * seen an inconsistent snapshot.
                     */
                    if (op == DTRACE_DYNVAR_NOALLOC) {
                              if (hash[bucket].dtdh_lock != lock)
                                        goto top;
                    } else {
                              ASSERT(op == DTRACE_DYNVAR_DEALLOC);
                              ASSERT(hash[bucket].dtdh_lock == lock);
                              ASSERT(lock & 1);
                              hash[bucket].dtdh_lock++;
                    }

                    return (NULL);
          }

          /*
           * We need to allocate a new dynamic variable.  The size we need is the
           * size of dtrace_dynvar plus the size of nkeys dtrace_key_t's plus the
           * size of any auxiliary key data (rounded up to 8-byte alignment) plus
           * the size of any referred-to data (dsize).  We then round the final
           * size up to the chunksize for allocation.
           */
          for (ksize = 0, i = 0; i < nkeys; i++)
                    ksize += P2ROUNDUP(key[i].dttk_size, sizeof (uint64_t));

          /*
           * This should be pretty much impossible, but could happen if, say,
           * strange DIF specified the tuple.  Ideally, this should be an
           * assertion and not an error condition -- but that requires that the
           * chunksize calculation in dtrace_difo_chunksize() be absolutely
           * bullet-proof.  (That is, it must not be able to be fooled by
           * malicious DIF.)  Given the lack of backwards branches in DIF,
           * solving this would presumably not amount to solving the Halting
           * Problem -- but it still seems awfully hard.
           */
          if (sizeof (dtrace_dynvar_t) + sizeof (dtrace_key_t) * (nkeys - 1) +
              ksize + dsize > chunksize) {
                    dcpu->dtdsc_drops++;
                    return (NULL);
          }

          nstate = DTRACE_DSTATE_EMPTY;

          do {
retry:
                    free = dcpu->dtdsc_free;

                    if (free == NULL) {
                              dtrace_dynvar_t *clean = dcpu->dtdsc_clean;
                              void *rval;

                              if (clean == NULL) {
                                        /*
                                         * We're out of dynamic variable space on
                                         * this CPU.  Unless we have tried all CPUs,
                                         * we'll try to allocate from a different
                                         * CPU.
                                         */
                                        switch (dstate->dtds_state) {
                                        case DTRACE_DSTATE_CLEAN: {
                                                  void *sp = &dstate->dtds_state;

                                                  if (++cpu >= NCPU)
                                                            cpu = 0;

                                                  if (dcpu->dtdsc_dirty != NULL &&
                                                      nstate == DTRACE_DSTATE_EMPTY)
                                                            nstate = DTRACE_DSTATE_DIRTY;

                                                  if (dcpu->dtdsc_rinsing != NULL)
                                                            nstate = DTRACE_DSTATE_RINSING;

                                                  dcpu = &dstate->dtds_percpu[cpu];

                                                  if (cpu != me)
                                                            goto retry;

                                                  (void) dtrace_cas32(sp,
                                                      DTRACE_DSTATE_CLEAN, nstate);

                                                  /*
                                                   * To increment the correct bean
                                                   * counter, take another lap.
                                                   */
                                                  goto retry;
                                        }

                                        case DTRACE_DSTATE_DIRTY:
                                                  dcpu->dtdsc_dirty_drops++;
                                                  break;

                                        case DTRACE_DSTATE_RINSING:
                                                  dcpu->dtdsc_rinsing_drops++;
                                                  break;

                                        case DTRACE_DSTATE_EMPTY:
                                                  dcpu->dtdsc_drops++;
                                                  break;
                                        }

                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_DROP);
                                        return (NULL);
                              }

                              /*
                               * The clean list appears to be non-empty.  We want to
                               * move the clean list to our free list; we start by
                               * moving the clean pointer aside.
                               */
                              if (dtrace_casptr(&dcpu->dtdsc_clean,
                                  clean, NULL) != clean) {
                                        /*
                                         * We are in one of two situations:
                                         *
                                         *  (a)   The clean list was switched to the
                                         *        free list by another CPU.
                                         *
                                         *  (b)   The clean list was added to by the
                                         *        cleansing cyclic.
                                         *
                                         * In either of these situations, we can
                                         * just reattempt the free list allocation.
                                         */
                                        goto retry;
                              }

                              ASSERT(clean->dtdv_hashval == DTRACE_DYNHASH_FREE);

                              /*
                               * Now we'll move the clean list to the free list.
                               * It's impossible for this to fail:  the only way
                               * the free list can be updated is through this
                               * code path, and only one CPU can own the clean list.
                               * Thus, it would only be possible for this to fail if
                               * this code were racing with dtrace_dynvar_clean().
                               * (That is, if dtrace_dynvar_clean() updated the clean
                               * list, and we ended up racing to update the free
                               * list.)  This race is prevented by the dtrace_sync()
                               * in dtrace_dynvar_clean() -- which flushes the
                               * owners of the clean lists out before resetting
                               * the clean lists.
                               */
                              dcpu = &dstate->dtds_percpu[me];
                              rval = dtrace_casptr(&dcpu->dtdsc_free, NULL, clean);
                              ASSERT(rval == NULL);
                              goto retry;
                    }

                    dvar = free;
                    new_free = dvar->dtdv_next;
          } while (dtrace_casptr(&dcpu->dtdsc_free, free, new_free) != free);

          /*
           * We have now allocated a new chunk.  We copy the tuple keys into the
           * tuple array and copy any referenced key data into the data space
           * following the tuple array.  As we do this, we relocate dttk_value
           * in the final tuple to point to the key data address in the chunk.
           */
          kdata = (uintptr_t)&dvar->dtdv_tuple.dtt_key[nkeys];
          dvar->dtdv_data = (void *)(kdata + ksize);
          dvar->dtdv_tuple.dtt_nkeys = nkeys;

          for (i = 0; i < nkeys; i++) {
                    dtrace_key_t *dkey = &dvar->dtdv_tuple.dtt_key[i];
                    size_t kesize = key[i].dttk_size;

                    if (kesize != 0) {
                              dtrace_bcopy(
                                  (const void *)(uintptr_t)key[i].dttk_value,
                                  (void *)kdata, kesize);
                              dkey->dttk_value = kdata;
                              kdata += P2ROUNDUP(kesize, sizeof (uint64_t));
                    } else {
                              dkey->dttk_value = key[i].dttk_value;
                    }

                    dkey->dttk_size = kesize;
          }

          ASSERT(dvar->dtdv_hashval == DTRACE_DYNHASH_FREE);
          dvar->dtdv_hashval = hashval;
          dvar->dtdv_next = start;

          if (dtrace_casptr(&hash[bucket].dtdh_chain, start, dvar) == start)
                    return (dvar);

          /*
           * The cas has failed.  Either another CPU is adding an element to
           * this hash chain, or another CPU is deleting an element from this
           * hash chain.  The simplest way to deal with both of these cases
           * (though not necessarily the most efficient) is to free our
           * allocated block and re-attempt it all.  Note that the free is
           * to the dirty list and _not_ to the free list.  This is to prevent
           * races with allocators, above.
           */
          dvar->dtdv_hashval = DTRACE_DYNHASH_FREE;

          dtrace_membar_producer();

          do {
                    free = dcpu->dtdsc_dirty;
                    dvar->dtdv_next = free;
          } while (dtrace_casptr(&dcpu->dtdsc_dirty, free, dvar) != free);

          goto top;
}

/*ARGSUSED*/
static void
dtrace_aggregate_min(uint64_t *oval, uint64_t nval, uint64_t arg)
{
          if ((int64_t)nval < (int64_t)*oval)
                    *oval = nval;
}

/*ARGSUSED*/
static void
dtrace_aggregate_max(uint64_t *oval, uint64_t nval, uint64_t arg)
{
          if ((int64_t)nval > (int64_t)*oval)
                    *oval = nval;
}

static void
dtrace_aggregate_quantize(uint64_t *quanta, uint64_t nval, uint64_t incr)
{
          int i, zero = DTRACE_QUANTIZE_ZEROBUCKET;
          int64_t val = (int64_t)nval;

          if (val < 0) {
                    for (i = 0; i < zero; i++) {
                              if (val <= DTRACE_QUANTIZE_BUCKETVAL(i)) {
                                        quanta[i] += incr;
                                        return;
                              }
                    }
          } else {
                    for (i = zero + 1; i < DTRACE_QUANTIZE_NBUCKETS; i++) {
                              if (val < DTRACE_QUANTIZE_BUCKETVAL(i)) {
                                        quanta[i - 1] += incr;
                                        return;
                              }
                    }

                    quanta[DTRACE_QUANTIZE_NBUCKETS - 1] += incr;
                    return;
          }

          ASSERT(0);
}

static void
dtrace_aggregate_lquantize(uint64_t *lquanta, uint64_t nval, uint64_t incr)
{
          uint64_t arg = *lquanta++;
          int32_t base = DTRACE_LQUANTIZE_BASE(arg);
          uint16_t step = DTRACE_LQUANTIZE_STEP(arg);
          uint16_t levels = DTRACE_LQUANTIZE_LEVELS(arg);
          int32_t val = (int32_t)nval, level;

          ASSERT(step != 0);
          ASSERT(levels != 0);

          if (val < base) {
                    /*
                     * This is an underflow.
                     */
                    lquanta[0] += incr;
                    return;
          }

          level = (val - base) / step;

          if (level < levels) {
                    lquanta[level + 1] += incr;
                    return;
          }

          /*
           * This is an overflow.
           */
          lquanta[levels + 1] += incr;
}

static int
dtrace_aggregate_llquantize_bucket(uint16_t factor, uint16_t low,
    uint16_t high, uint16_t nsteps, int64_t value)
{
          int64_t this = 1, last, next;
          int base = 1, order;

          ASSERT(factor <= nsteps);
          ASSERT(nsteps % factor == 0);

          for (order = 0; order < low; order++)
                    this *= factor;

          /*
           * If our value is less than our factor taken to the power of the
           * low order of magnitude, it goes into the zeroth bucket.
           */
          if (value < (last = this))
                    return (0);

          for (this *= factor; order <= high; order++) {
                    int nbuckets = this > nsteps ? nsteps : this;

                    if ((next = this * factor) < this) {
                              /*
                               * We should not generally get log/linear quantizations
                               * with a high magnitude that allows 64-bits to
                               * overflow, but we nonetheless protect against this
                               * by explicitly checking for overflow, and clamping
                               * our value accordingly.
                               */
                              value = this - 1;
                    }

                    if (value < this) {
                              /*
                               * If our value lies within this order of magnitude,
                               * determine its position by taking the offset within
                               * the order of magnitude, dividing by the bucket
                               * width, and adding to our (accumulated) base.
                               */
                              return (base + (value - last) / (this / nbuckets));
                    }

                    base += nbuckets - (nbuckets / factor);
                    last = this;
                    this = next;
          }

          /*
           * Our value is greater than or equal to our factor taken to the
           * power of one plus the high magnitude -- return the top bucket.
           */
          return (base);
}

static void
dtrace_aggregate_llquantize(uint64_t *llquanta, uint64_t nval, uint64_t incr)
{
          uint64_t arg = *llquanta++;
          uint16_t factor = DTRACE_LLQUANTIZE_FACTOR(arg);
          uint16_t low = DTRACE_LLQUANTIZE_LOW(arg);
          uint16_t high = DTRACE_LLQUANTIZE_HIGH(arg);
          uint16_t nsteps = DTRACE_LLQUANTIZE_NSTEP(arg);

          llquanta[dtrace_aggregate_llquantize_bucket(factor,
              low, high, nsteps, nval)] += incr;
}

/*ARGSUSED*/
static void
dtrace_aggregate_avg(uint64_t *data, uint64_t nval, uint64_t arg)
{
          data[0]++;
          data[1] += nval;
}

/*ARGSUSED*/
static void
dtrace_aggregate_stddev(uint64_t *data, uint64_t nval, uint64_t arg)
{
          int64_t snval = (int64_t)nval;
          uint64_t tmp[2];

          data[0]++;
          data[1] += nval;

          /*
           * What we want to say here is:
           *
           * data[2] += nval * nval;
           *
           * But given that nval is 64-bit, we could easily overflow, so
           * we do this as 128-bit arithmetic.
           */
          if (snval < 0)
                    snval = -snval;

          dtrace_multiply_128((uint64_t)snval, (uint64_t)snval, tmp);
          dtrace_add_128(data + 2, tmp, data + 2);
}

/*ARGSUSED*/
static void
dtrace_aggregate_count(uint64_t *oval, uint64_t nval, uint64_t arg)
{
          *oval = *oval + 1;
}

/*ARGSUSED*/
static void
dtrace_aggregate_sum(uint64_t *oval, uint64_t nval, uint64_t arg)
{
          *oval += nval;
}

/*
 * Aggregate given the tuple in the principal data buffer, and the aggregating
 * action denoted by the specified dtrace_aggregation_t.  The aggregation
 * buffer is specified as the buf parameter.  This routine does not return
 * failure; if there is no space in the aggregation buffer, the data will be
 * dropped, and a corresponding counter incremented.
 */
static void
dtrace_aggregate(dtrace_aggregation_t *agg, dtrace_buffer_t *dbuf,
    intptr_t offset, dtrace_buffer_t *buf, uint64_t expr, uint64_t arg)
{
          dtrace_recdesc_t *rec = &agg->dtag_action.dta_rec;
          uint32_t i, ndx, size, fsize;
          uint32_t align = sizeof (uint64_t) - 1;
          dtrace_aggbuffer_t *agb;
          dtrace_aggkey_t *key;
          uint32_t hashval = 0, limit, isstr;
          caddr_t tomax, data, kdata;
          dtrace_actkind_t action;
          dtrace_action_t *act;
          uintptr_t offs;

          if (buf == NULL)
                    return;

          if (!agg->dtag_hasarg) {
                    /*
                     * Currently, only quantize() and lquantize() take additional
                     * arguments, and they have the same semantics:  an increment
                     * value that defaults to 1 when not present.  If additional
                     * aggregating actions take arguments, the setting of the
                     * default argument value will presumably have to become more
                     * sophisticated...
                     */
                    arg = 1;
          }

          action = agg->dtag_action.dta_kind - DTRACEACT_AGGREGATION;
          size = rec->dtrd_offset - agg->dtag_base;
          fsize = size + rec->dtrd_size;

          ASSERT(dbuf->dtb_tomax != NULL);
          data = dbuf->dtb_tomax + offset + agg->dtag_base;

          if ((tomax = buf->dtb_tomax) == NULL) {
                    dtrace_buffer_drop(buf);
                    return;
          }

          /*
           * The metastructure is always at the bottom of the buffer.
           */
          agb = (dtrace_aggbuffer_t *)(tomax + buf->dtb_size -
              sizeof (dtrace_aggbuffer_t));

          if (buf->dtb_offset == 0) {
                    /*
                     * We just kludge up approximately 1/8th of the size to be
                     * buckets.  If this guess ends up being routinely
                     * off-the-mark, we may need to dynamically readjust this
                     * based on past performance.
                     */
                    uintptr_t hashsize = (buf->dtb_size >> 3) / sizeof (uintptr_t);

                    if ((uintptr_t)agb - hashsize * sizeof (dtrace_aggkey_t *) <
                        (uintptr_t)tomax || hashsize == 0) {
                              /*
                               * We've been given a ludicrously small buffer;
                               * increment our drop count and leave.
                               */
                              dtrace_buffer_drop(buf);
                              return;
                    }

                    /*
                     * And now, a pathetic attempt to try to get a an odd (or
                     * perchance, a prime) hash size for better hash distribution.
                     */
                    if (hashsize > (DTRACE_AGGHASHSIZE_SLEW << 3))
                              hashsize -= DTRACE_AGGHASHSIZE_SLEW;

                    agb->dtagb_hashsize = hashsize;
                    agb->dtagb_hash = (dtrace_aggkey_t **)((uintptr_t)agb -
                        agb->dtagb_hashsize * sizeof (dtrace_aggkey_t *));
                    agb->dtagb_free = (uintptr_t)agb->dtagb_hash;

                    for (i = 0; i < agb->dtagb_hashsize; i++)
                              agb->dtagb_hash[i] = NULL;
          }

          ASSERT(agg->dtag_first != NULL);
          ASSERT(agg->dtag_first->dta_intuple);

          /*
           * Calculate the hash value based on the key.  Note that we _don't_
           * include the aggid in the hashing (but we will store it as part of
           * the key).  The hashing algorithm is Bob Jenkins' "One-at-a-time"
           * algorithm: a simple, quick algorithm that has no known funnels, and
           * gets good distribution in practice.  The efficacy of the hashing
           * algorithm (and a comparison with other algorithms) may be found by
           * running the ::dtrace_aggstat MDB dcmd.
           */
          for (act = agg->dtag_first; act->dta_intuple; act = act->dta_next) {
                    i = act->dta_rec.dtrd_offset - agg->dtag_base;
                    limit = i + act->dta_rec.dtrd_size;
                    ASSERT(limit <= size);
                    isstr = DTRACEACT_ISSTRING(act);

                    for (; i < limit; i++) {
                              hashval += data[i];
                              hashval += (hashval << 10);
                              hashval ^= (hashval >> 6);

                              if (isstr && data[i] == '\0')
                                        break;
                    }
          }

          hashval += (hashval << 3);
          hashval ^= (hashval >> 11);
          hashval += (hashval << 15);

          /*
           * Yes, the divide here is expensive -- but it's generally the least
           * of the performance issues given the amount of data that we iterate
           * over to compute hash values, compare data, etc.
           */
          ndx = hashval % agb->dtagb_hashsize;

          for (key = agb->dtagb_hash[ndx]; key != NULL; key = key->dtak_next) {
                    ASSERT((caddr_t)key >= tomax);
                    ASSERT((caddr_t)key < tomax + buf->dtb_size);

                    if (hashval != key->dtak_hashval || key->dtak_size != size)
                              continue;

                    kdata = key->dtak_data;
                    ASSERT(kdata >= tomax && kdata < tomax + buf->dtb_size);

                    for (act = agg->dtag_first; act->dta_intuple;
                        act = act->dta_next) {
                              i = act->dta_rec.dtrd_offset - agg->dtag_base;
                              limit = i + act->dta_rec.dtrd_size;
                              ASSERT(limit <= size);
                              isstr = DTRACEACT_ISSTRING(act);

                              for (; i < limit; i++) {
                                        if (kdata[i] != data[i])
                                                  goto next;

                                        if (isstr && data[i] == '\0')
                                                  break;
                              }
                    }

                    if (action != key->dtak_action) {
                              /*
                               * We are aggregating on the same value in the same
                               * aggregation with two different aggregating actions.
                               * (This should have been picked up in the compiler,
                               * so we may be dealing with errant or devious DIF.)
                               * This is an error condition; we indicate as much,
                               * and return.
                               */
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                              return;
                    }

                    /*
                     * This is a hit:  we need to apply the aggregator to
                     * the value at this key.
                     */
                    agg->dtag_aggregate((uint64_t *)(kdata + size), expr, arg);
                    return;
next:
                    continue;
          }

          /*
           * We didn't find it.  We need to allocate some zero-filled space,
           * link it into the hash table appropriately, and apply the aggregator
           * to the (zero-filled) value.
           */
          offs = buf->dtb_offset;
          while (offs & (align - 1))
                    offs += sizeof (uint32_t);

          /*
           * If we don't have enough room to both allocate a new key _and_
           * its associated data, increment the drop count and return.
           */
          if ((uintptr_t)tomax + offs + fsize >
              agb->dtagb_free - sizeof (dtrace_aggkey_t)) {
                    dtrace_buffer_drop(buf);
                    return;
          }

          /*CONSTCOND*/
          ASSERT(!(sizeof (dtrace_aggkey_t) & (sizeof (uintptr_t) - 1)));
          key = (dtrace_aggkey_t *)(agb->dtagb_free - sizeof (dtrace_aggkey_t));
          agb->dtagb_free -= sizeof (dtrace_aggkey_t);

          key->dtak_data = kdata = tomax + offs;
          buf->dtb_offset = offs + fsize;

          /*
           * Now copy the data across.
           */
          *((dtrace_aggid_t *)kdata) = agg->dtag_id;

          for (i = sizeof (dtrace_aggid_t); i < size; i++)
                    kdata[i] = data[i];

          /*
           * Because strings are not zeroed out by default, we need to iterate
           * looking for actions that store strings, and we need to explicitly
           * pad these strings out with zeroes.
           */
          for (act = agg->dtag_first; act->dta_intuple; act = act->dta_next) {
                    int nul;

                    if (!DTRACEACT_ISSTRING(act))
                              continue;

                    i = act->dta_rec.dtrd_offset - agg->dtag_base;
                    limit = i + act->dta_rec.dtrd_size;
                    ASSERT(limit <= size);

                    for (nul = 0; i < limit; i++) {
                              if (nul) {
                                        kdata[i] = '\0';
                                        continue;
                              }

                              if (data[i] != '\0')
                                        continue;

                              nul = 1;
                    }
          }

          for (i = size; i < fsize; i++)
                    kdata[i] = 0;

          key->dtak_hashval = hashval;
          key->dtak_size = size;
          key->dtak_action = action;
          key->dtak_next = agb->dtagb_hash[ndx];
          agb->dtagb_hash[ndx] = key;

          /*
           * Finally, apply the aggregator.
           */
          *((uint64_t *)(key->dtak_data + size)) = agg->dtag_initial;
          agg->dtag_aggregate((uint64_t *)(key->dtak_data + size), expr, arg);
}

/*
 * Given consumer state, this routine finds a speculation in the INACTIVE
 * state and transitions it into the ACTIVE state.  If there is no speculation
 * in the INACTIVE state, 0 is returned.  In this case, no error counter is
 * incremented -- it is up to the caller to take appropriate action.
 */
static int
dtrace_speculation(dtrace_state_t *state)
{
          int i = 0;
          dtrace_speculation_state_t current;
          uint32_t *stat = &state->dts_speculations_unavail, count;

          while (i < state->dts_nspeculations) {
                    dtrace_speculation_t *spec = &state->dts_speculations[i];

                    current = spec->dtsp_state;

                    if (current != DTRACESPEC_INACTIVE) {
                              if (current == DTRACESPEC_COMMITTINGMANY ||
                                  current == DTRACESPEC_COMMITTING ||
                                  current == DTRACESPEC_DISCARDING)
                                        stat = &state->dts_speculations_busy;
                              i++;
                              continue;
                    }

                    if (dtrace_cas32((uint32_t *)&spec->dtsp_state,
                        current, DTRACESPEC_ACTIVE) == current)
                              return (i + 1);
          }

          /*
           * We couldn't find a speculation.  If we found as much as a single
           * busy speculation buffer, we'll attribute this failure as "busy"
           * instead of "unavail".
           */
          do {
                    count = *stat;
          } while (dtrace_cas32(stat, count, count + 1) != count);

          return (0);
}

/*
 * This routine commits an active speculation.  If the specified speculation
 * is not in a valid state to perform a commit(), this routine will silently do
 * nothing.  The state of the specified speculation is transitioned according
 * to the state transition diagram outlined in <sys/dtrace_impl.h>
 */
static void
dtrace_speculation_commit(dtrace_state_t *state, processorid_t cpu,
    dtrace_specid_t which)
{
          dtrace_speculation_t *spec;
          dtrace_buffer_t *src, *dest;
          uintptr_t daddr, saddr, dlimit, slimit;
          dtrace_speculation_state_t current, new = 0;
          intptr_t offs;
          uint64_t timestamp;

          if (which == 0)
                    return;

          if (which > state->dts_nspeculations) {
                    cpu_core[cpu].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
                    return;
          }

          spec = &state->dts_speculations[which - 1];
          src = &spec->dtsp_buffer[cpu];
          dest = &state->dts_buffer[cpu];

          do {
                    current = spec->dtsp_state;

                    if (current == DTRACESPEC_COMMITTINGMANY)
                              break;

                    switch (current) {
                    case DTRACESPEC_INACTIVE:
                    case DTRACESPEC_DISCARDING:
                              return;

                    case DTRACESPEC_COMMITTING:
                              /*
                               * This is only possible if we are (a) commit()'ing
                               * without having done a prior speculate() on this CPU
                               * and (b) racing with another commit() on a different
                               * CPU.  There's nothing to do -- we just assert that
                               * our offset is 0.
                               */
                              ASSERT(src->dtb_offset == 0);
                              return;

                    case DTRACESPEC_ACTIVE:
                              new = DTRACESPEC_COMMITTING;
                              break;

                    case DTRACESPEC_ACTIVEONE:
                              /*
                               * This speculation is active on one CPU.  If our
                               * buffer offset is non-zero, we know that the one CPU
                               * must be us.  Otherwise, we are committing on a
                               * different CPU from the speculate(), and we must
                               * rely on being asynchronously cleaned.
                               */
                              if (src->dtb_offset != 0) {
                                        new = DTRACESPEC_COMMITTING;
                                        break;
                              }
                              /*FALLTHROUGH*/

                    case DTRACESPEC_ACTIVEMANY:
                              new = DTRACESPEC_COMMITTINGMANY;
                              break;

                    default:
                              ASSERT(0);
                    }
          } while (dtrace_cas32((uint32_t *)&spec->dtsp_state,
              current, new) != current);

          /*
           * We have set the state to indicate that we are committing this
           * speculation.  Now reserve the necessary space in the destination
           * buffer.
           */
          if ((offs = dtrace_buffer_reserve(dest, src->dtb_offset,
              sizeof (uint64_t), state, NULL)) < 0) {
                    dtrace_buffer_drop(dest);
                    goto out;
          }

          /*
           * We have sufficient space to copy the speculative buffer into the
           * primary buffer.  First, modify the speculative buffer, filling
           * in the timestamp of all entries with the current time.  The data
           * must have the commit() time rather than the time it was traced,
           * so that all entries in the primary buffer are in timestamp order.
           */
          timestamp = dtrace_gethrtime();
          saddr = (uintptr_t)src->dtb_tomax;
          slimit = saddr + src->dtb_offset;
          while (saddr < slimit) {
                    size_t size;
                    dtrace_rechdr_t *dtrh = (dtrace_rechdr_t *)saddr;

                    if (dtrh->dtrh_epid == DTRACE_EPIDNONE) {
                              saddr += sizeof (dtrace_epid_t);
                              continue;
                    }
                    ASSERT3U(dtrh->dtrh_epid, <=, state->dts_necbs);
                    size = state->dts_ecbs[dtrh->dtrh_epid - 1]->dte_size;

                    ASSERT3U(saddr + size, <=, slimit);
                    ASSERT3U(size, >=, sizeof (dtrace_rechdr_t));
                    ASSERT3U(DTRACE_RECORD_LOAD_TIMESTAMP(dtrh), ==, UINT64_MAX);

                    DTRACE_RECORD_STORE_TIMESTAMP(dtrh, timestamp);

                    saddr += size;
          }

          /*
           * Copy the buffer across.  (Note that this is a
           * highly subobtimal bcopy(); in the unlikely event that this becomes
           * a serious performance issue, a high-performance DTrace-specific
           * bcopy() should obviously be invented.)
           */
          daddr = (uintptr_t)dest->dtb_tomax + offs;
          dlimit = daddr + src->dtb_offset;
          saddr = (uintptr_t)src->dtb_tomax;

          /*
           * First, the aligned portion.
           */
          while (dlimit - daddr >= sizeof (uint64_t)) {
                    *((uint64_t *)daddr) = *((uint64_t *)saddr);

                    daddr += sizeof (uint64_t);
                    saddr += sizeof (uint64_t);
          }

          /*
           * Now any left-over bit...
           */
          while (dlimit - daddr)
                    *((uint8_t *)daddr++) = *((uint8_t *)saddr++);

          /*
           * Finally, commit the reserved space in the destination buffer.
           */
          dest->dtb_offset = offs + src->dtb_offset;

out:
          /*
           * If we're lucky enough to be the only active CPU on this speculation
           * buffer, we can just set the state back to DTRACESPEC_INACTIVE.
           */
          if (current == DTRACESPEC_ACTIVE ||
              (current == DTRACESPEC_ACTIVEONE && new == DTRACESPEC_COMMITTING)) {
                    uint32_t rval = dtrace_cas32((uint32_t *)&spec->dtsp_state,
                        DTRACESPEC_COMMITTING, DTRACESPEC_INACTIVE);

                    ASSERT(rval == DTRACESPEC_COMMITTING);
          }

          src->dtb_offset = 0;
          src->dtb_xamot_drops += src->dtb_drops;
          src->dtb_drops = 0;
}

/*
 * This routine discards an active speculation.  If the specified speculation
 * is not in a valid state to perform a discard(), this routine will silently
 * do nothing.  The state of the specified speculation is transitioned
 * according to the state transition diagram outlined in <sys/dtrace_impl.h>
 */
static void
dtrace_speculation_discard(dtrace_state_t *state, processorid_t cpu,
    dtrace_specid_t which)
{
          dtrace_speculation_t *spec;
          dtrace_speculation_state_t current, new = 0;
          dtrace_buffer_t *buf;

          if (which == 0)
                    return;

          if (which > state->dts_nspeculations) {
                    cpu_core[cpu].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
                    return;
          }

          spec = &state->dts_speculations[which - 1];
          buf = &spec->dtsp_buffer[cpu];

          do {
                    current = spec->dtsp_state;

                    switch (current) {
                    case DTRACESPEC_INACTIVE:
                    case DTRACESPEC_COMMITTINGMANY:
                    case DTRACESPEC_COMMITTING:
                    case DTRACESPEC_DISCARDING:
                              return;

                    case DTRACESPEC_ACTIVE:
                    case DTRACESPEC_ACTIVEMANY:
                              new = DTRACESPEC_DISCARDING;
                              break;

                    case DTRACESPEC_ACTIVEONE:
                              if (buf->dtb_offset != 0) {
                                        new = DTRACESPEC_INACTIVE;
                              } else {
                                        new = DTRACESPEC_DISCARDING;
                              }
                              break;

                    default:
                              ASSERT(0);
                    }
          } while (dtrace_cas32((uint32_t *)&spec->dtsp_state,
              current, new) != current);

          buf->dtb_offset = 0;
          buf->dtb_drops = 0;
}

/*
 * Note:  not called from probe context.  This function is called
 * asynchronously from cross call context to clean any speculations that are
 * in the COMMITTINGMANY or DISCARDING states.  These speculations may not be
 * transitioned back to the INACTIVE state until all CPUs have cleaned the
 * speculation.
 */
static void
dtrace_speculation_clean_here(dtrace_state_t *state)
{
          dtrace_icookie_t cookie;
          processorid_t cpu = curcpu_id;
          dtrace_buffer_t *dest = &state->dts_buffer[cpu];
          dtrace_specid_t i;

          cookie = dtrace_interrupt_disable();

          if (dest->dtb_tomax == NULL) {
                    dtrace_interrupt_enable(cookie);
                    return;
          }

          for (i = 0; i < state->dts_nspeculations; i++) {
                    dtrace_speculation_t *spec = &state->dts_speculations[i];
                    dtrace_buffer_t *src = &spec->dtsp_buffer[cpu];

                    if (src->dtb_tomax == NULL)
                              continue;

                    if (spec->dtsp_state == DTRACESPEC_DISCARDING) {
                              src->dtb_offset = 0;
                              continue;
                    }

                    if (spec->dtsp_state != DTRACESPEC_COMMITTINGMANY)
                              continue;

                    if (src->dtb_offset == 0)
                              continue;

                    dtrace_speculation_commit(state, cpu, i + 1);
          }

          dtrace_interrupt_enable(cookie);
}

/*
 * Note:  not called from probe context.  This function is called
 * asynchronously (and at a regular interval) to clean any speculations that
 * are in the COMMITTINGMANY or DISCARDING states.  If it discovers that there
 * is work to be done, it cross calls all CPUs to perform that work;
 * COMMITMANY and DISCARDING speculations may not be transitioned back to the
 * INACTIVE state until they have been cleaned by all CPUs.
 */
static void
dtrace_speculation_clean(dtrace_state_t *state)
{
          int work = 0, rv;
          dtrace_specid_t i;

          for (i = 0; i < state->dts_nspeculations; i++) {
                    dtrace_speculation_t *spec = &state->dts_speculations[i];

                    ASSERT(!spec->dtsp_cleaning);

                    if (spec->dtsp_state != DTRACESPEC_DISCARDING &&
                        spec->dtsp_state != DTRACESPEC_COMMITTINGMANY)
                              continue;

                    work++;
                    spec->dtsp_cleaning = 1;
          }

          if (!work)
                    return;

          dtrace_xcall(DTRACE_CPUALL,
              (dtrace_xcall_t)dtrace_speculation_clean_here, state);

          /*
           * We now know that all CPUs have committed or discarded their
           * speculation buffers, as appropriate.  We can now set the state
           * to inactive.
           */
          for (i = 0; i < state->dts_nspeculations; i++) {
                    dtrace_speculation_t *spec = &state->dts_speculations[i];
                    dtrace_speculation_state_t current, new;

                    if (!spec->dtsp_cleaning)
                              continue;

                    current = spec->dtsp_state;
                    ASSERT(current == DTRACESPEC_DISCARDING ||
                        current == DTRACESPEC_COMMITTINGMANY);

                    new = DTRACESPEC_INACTIVE;

                    rv = dtrace_cas32((uint32_t *)&spec->dtsp_state, current, new);
                    ASSERT(rv == current);
                    spec->dtsp_cleaning = 0;
          }
}

/*
 * Called as part of a speculate() to get the speculative buffer associated
 * with a given speculation.  Returns NULL if the specified speculation is not
 * in an ACTIVE state.  If the speculation is in the ACTIVEONE state -- and
 * the active CPU is not the specified CPU -- the speculation will be
 * atomically transitioned into the ACTIVEMANY state.
 */
static dtrace_buffer_t *
dtrace_speculation_buffer(dtrace_state_t *state, processorid_t cpuid,
    dtrace_specid_t which)
{
          dtrace_speculation_t *spec;
          dtrace_speculation_state_t current, new = 0;
          dtrace_buffer_t *buf;

          if (which == 0)
                    return (NULL);

          if (which > state->dts_nspeculations) {
                    cpu_core[cpuid].cpuc_dtrace_flags |= CPU_DTRACE_ILLOP;
                    return (NULL);
          }

          spec = &state->dts_speculations[which - 1];
          buf = &spec->dtsp_buffer[cpuid];

          do {
                    current = spec->dtsp_state;

                    switch (current) {
                    case DTRACESPEC_INACTIVE:
                    case DTRACESPEC_COMMITTINGMANY:
                    case DTRACESPEC_DISCARDING:
                              return (NULL);

                    case DTRACESPEC_COMMITTING:
                              ASSERT(buf->dtb_offset == 0);
                              return (NULL);

                    case DTRACESPEC_ACTIVEONE:
                              /*
                               * This speculation is currently active on one CPU.
                               * Check the offset in the buffer; if it's non-zero,
                               * that CPU must be us (and we leave the state alone).
                               * If it's zero, assume that we're starting on a new
                               * CPU -- and change the state to indicate that the
                               * speculation is active on more than one CPU.
                               */
                              if (buf->dtb_offset != 0)
                                        return (buf);

                              new = DTRACESPEC_ACTIVEMANY;
                              break;

                    case DTRACESPEC_ACTIVEMANY:
                              return (buf);

                    case DTRACESPEC_ACTIVE:
                              new = DTRACESPEC_ACTIVEONE;
                              break;

                    default:
                              ASSERT(0);
                    }
          } while (dtrace_cas32((uint32_t *)&spec->dtsp_state,
              current, new) != current);

          ASSERT(new == DTRACESPEC_ACTIVEONE || new == DTRACESPEC_ACTIVEMANY);
          return (buf);
}

/*
 * Return a string.  In the event that the user lacks the privilege to access
 * arbitrary kernel memory, we copy the string out to scratch memory so that we
 * don't fail access checking.
 *
 * dtrace_dif_variable() uses this routine as a helper for various
 * builtin values such as 'execname' and 'probefunc.'
 */
uintptr_t
dtrace_dif_varstr(uintptr_t addr, dtrace_state_t *state,
    dtrace_mstate_t *mstate)
{
          uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
          uintptr_t ret;
          size_t strsz;

          /*
           * The easy case: this probe is allowed to read all of memory, so
           * we can just return this as a vanilla pointer.
           */
          if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) != 0)
                    return (addr);

          /*
           * This is the tougher case: we copy the string in question from
           * kernel memory into scratch memory and return it that way: this
           * ensures that we won't trip up when access checking tests the
           * BYREF return value.
           */
          strsz = dtrace_strlen((char *)addr, size) + 1;

          if (mstate->dtms_scratch_ptr + strsz >
              mstate->dtms_scratch_base + mstate->dtms_scratch_size) {
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                    return (0);
          }

          dtrace_strcpy((const void *)addr, (void *)mstate->dtms_scratch_ptr,
              strsz);
          ret = mstate->dtms_scratch_ptr;
          mstate->dtms_scratch_ptr += strsz;
          return (ret);
}

/*
 * Return a string from a memoy address which is known to have one or
 * more concatenated, individually zero terminated, sub-strings.
 * In the event that the user lacks the privilege to access
 * arbitrary kernel memory, we copy the string out to scratch memory so that we
 * don't fail access checking.
 *
 * dtrace_dif_variable() uses this routine as a helper for various
 * builtin values such as 'execargs'.
 */
static uintptr_t
dtrace_dif_varstrz(uintptr_t addr, size_t strsz, dtrace_state_t *state,
    dtrace_mstate_t *mstate)
{
          char *p;
          size_t i;
          uintptr_t ret;

          if (mstate->dtms_scratch_ptr + strsz >
              mstate->dtms_scratch_base + mstate->dtms_scratch_size) {
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                    return (0);
          }

          dtrace_bcopy((const void *)addr, (void *)mstate->dtms_scratch_ptr,
              strsz);

          /* Replace sub-string termination characters with a space. */
          for (p = (char *) mstate->dtms_scratch_ptr, i = 0; i < strsz - 1;
              p++, i++)
                    if (*p == '\0')
                              *p = ' ';

          ret = mstate->dtms_scratch_ptr;
          mstate->dtms_scratch_ptr += strsz;
          return (ret);
}

/*
 * This function implements the DIF emulator's variable lookups.  The emulator
 * passes a reserved variable identifier and optional built-in array index.
 */
static uint64_t
dtrace_dif_variable(dtrace_mstate_t *mstate, dtrace_state_t *state, uint64_t v,
    uint64_t ndx)
{
          /*
           * If we're accessing one of the uncached arguments, we'll turn this
           * into a reference in the args array.
           */
          if (v >= DIF_VAR_ARG0 && v <= DIF_VAR_ARG9) {
                    ndx = v - DIF_VAR_ARG0;
                    v = DIF_VAR_ARGS;
          }

          switch (v) {
          case DIF_VAR_ARGS:
                    ASSERT(mstate->dtms_present & DTRACE_MSTATE_ARGS);
                    if (ndx >= sizeof (mstate->dtms_arg) /
                        sizeof (mstate->dtms_arg[0])) {
                              int aframes = mstate->dtms_probe->dtpr_aframes + 2;
                              dtrace_provider_t *pv;
                              uint64_t val;

                              pv = mstate->dtms_probe->dtpr_provider;
                              if (pv->dtpv_pops.dtps_getargval != NULL)
                                        val = pv->dtpv_pops.dtps_getargval(pv->dtpv_arg,
                                            mstate->dtms_probe->dtpr_id,
                                            mstate->dtms_probe->dtpr_arg, ndx, aframes);
                              else
                                        val = dtrace_getarg(ndx, aframes);

                              /*
                               * This is regrettably required to keep the compiler
                               * from tail-optimizing the call to dtrace_getarg().
                               * The condition always evaluates to true, but the
                               * compiler has no way of figuring that out a priori.
                               * (None of this would be necessary if the compiler
                               * could be relied upon to _always_ tail-optimize
                               * the call to dtrace_getarg() -- but it can't.)
                               */
                              if (mstate->dtms_probe != NULL)
                                        return (val);

                              ASSERT(0);
                    }

                    return (mstate->dtms_arg[ndx]);

#ifdef illumos
          case DIF_VAR_UREGS: {
                    klwp_t *lwp;

                    if (!dtrace_priv_proc(state))
                              return (0);

                    if ((lwp = curthread->t_lwp) == NULL) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                              cpu_core[curcpu_id].cpuc_dtrace_illval = NULL;
                              return (0);
                    }

                    return (dtrace_getreg(lwp->lwp_regs, ndx));
                    return (0);
          }
#endif
#ifdef __FreeBSD__
          case DIF_VAR_UREGS: {
                    struct trapframe *tframe;

                    if (!dtrace_priv_proc(state))
                              return (0);

                    if ((tframe = curthread->td_frame) == NULL) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                              cpu_core[curcpu].cpuc_dtrace_illval = 0;
                              return (0);
                    }

                    return (dtrace_getreg(tframe, ndx));
          }
#endif
#ifdef __NetBSD__
          case DIF_VAR_UREGS: {
                    struct trapframe *tframe;

                    if (!dtrace_priv_proc(state))
                              return (0);

                    if ((tframe = lwp_trapframe(curlwp)) == NULL) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_BADADDR);
                              cpu_core[curcpu_id].cpuc_dtrace_illval = 0;
                              return (0);
                    }

                    return (dtrace_getreg(tframe, ndx));
          }
#endif

          case DIF_VAR_CURTHREAD:
                    if (!dtrace_priv_proc(state))
                              return (0);
                    return ((uint64_t)(uintptr_t)curthread);

          case DIF_VAR_TIMESTAMP:
                    if (!(mstate->dtms_present & DTRACE_MSTATE_TIMESTAMP)) {
                              mstate->dtms_timestamp = dtrace_gethrtime();
                              mstate->dtms_present |= DTRACE_MSTATE_TIMESTAMP;
                    }
                    return (mstate->dtms_timestamp);

          case DIF_VAR_VTIMESTAMP:
                    ASSERT(dtrace_vtime_references != 0);
                    return (curthread->t_dtrace_vtime);

          case DIF_VAR_WALLTIMESTAMP:
                    if (!(mstate->dtms_present & DTRACE_MSTATE_WALLTIMESTAMP)) {
                              mstate->dtms_walltimestamp = dtrace_gethrestime();
                              mstate->dtms_present |= DTRACE_MSTATE_WALLTIMESTAMP;
                    }
                    return (mstate->dtms_walltimestamp);

#ifdef illumos
          case DIF_VAR_IPL:
                    if (!dtrace_priv_kernel(state))
                              return (0);
                    if (!(mstate->dtms_present & DTRACE_MSTATE_IPL)) {
                              mstate->dtms_ipl = dtrace_getipl();
                              mstate->dtms_present |= DTRACE_MSTATE_IPL;
                    }
                    return (mstate->dtms_ipl);
#endif

          case DIF_VAR_EPID:
                    ASSERT(mstate->dtms_present & DTRACE_MSTATE_EPID);
                    return (mstate->dtms_epid);

          case DIF_VAR_ID:
                    ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                    return (mstate->dtms_probe->dtpr_id);

          case DIF_VAR_STACKDEPTH:
                    if (!dtrace_priv_kernel(state))
                              return (0);
                    if (!(mstate->dtms_present & DTRACE_MSTATE_STACKDEPTH)) {
                              int aframes = mstate->dtms_probe->dtpr_aframes + 2;

                              mstate->dtms_stackdepth = dtrace_getstackdepth(aframes);
                              mstate->dtms_present |= DTRACE_MSTATE_STACKDEPTH;
                    }
                    return (mstate->dtms_stackdepth);

          case DIF_VAR_USTACKDEPTH:
                    if (!dtrace_priv_proc(state))
                              return (0);
                    if (!(mstate->dtms_present & DTRACE_MSTATE_USTACKDEPTH)) {
                              /*
                               * See comment in DIF_VAR_PID.
                               */
                              if (DTRACE_ANCHORED(mstate->dtms_probe) &&
                                  CPU_ON_INTR(CPU)) {
                                        mstate->dtms_ustackdepth = 0;
                              } else {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                        mstate->dtms_ustackdepth =
                                            dtrace_getustackdepth();
                                        DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              }
                              mstate->dtms_present |= DTRACE_MSTATE_USTACKDEPTH;
                    }
                    return (mstate->dtms_ustackdepth);

          case DIF_VAR_CALLER:
                    if (!dtrace_priv_kernel(state))
                              return (0);
                    if (!(mstate->dtms_present & DTRACE_MSTATE_CALLER)) {
                              int aframes = mstate->dtms_probe->dtpr_aframes + 2;

                              if (!DTRACE_ANCHORED(mstate->dtms_probe)) {
                                        /*
                                         * If this is an unanchored probe, we are
                                         * required to go through the slow path:
                                         * dtrace_caller() only guarantees correct
                                         * results for anchored probes.
                                         */
                                        pc_t caller[2] = {0, 0};

                                        dtrace_getpcstack(caller, 2, aframes,
                                            (uint32_t *)(uintptr_t)mstate->dtms_arg[0]);
                                        mstate->dtms_caller = caller[1];
                              } else if ((mstate->dtms_caller =
                                  dtrace_caller(aframes)) == -1) {
                                        /*
                                         * We have failed to do this the quick way;
                                         * we must resort to the slower approach of
                                         * calling dtrace_getpcstack().
                                         */
                                        pc_t caller = 0;

                                        dtrace_getpcstack(&caller, 1, aframes, NULL);
                                        mstate->dtms_caller = caller;
                              }

                              mstate->dtms_present |= DTRACE_MSTATE_CALLER;
                    }
                    return (mstate->dtms_caller);

          case DIF_VAR_UCALLER:
                    if (!dtrace_priv_proc(state))
                              return (0);

                    if (!(mstate->dtms_present & DTRACE_MSTATE_UCALLER)) {
                              uint64_t ustack[3];

                              /*
                               * dtrace_getupcstack() fills in the first uint64_t
                               * with the current PID.  The second uint64_t will
                               * be the program counter at user-level.  The third
                               * uint64_t will contain the caller, which is what
                               * we're after.
                               */
                              ustack[2] = 0;
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              dtrace_getupcstack(ustack, 3);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              mstate->dtms_ucaller = ustack[2];
                              mstate->dtms_present |= DTRACE_MSTATE_UCALLER;
                    }

                    return (mstate->dtms_ucaller);

          case DIF_VAR_PROBEPROV:
                    ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                    return (dtrace_dif_varstr(
                        (uintptr_t)mstate->dtms_probe->dtpr_provider->dtpv_name,
                        state, mstate));

          case DIF_VAR_PROBEMOD:
                    ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                    return (dtrace_dif_varstr(
                        (uintptr_t)mstate->dtms_probe->dtpr_mod,
                        state, mstate));

          case DIF_VAR_PROBEFUNC:
                    ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                    return (dtrace_dif_varstr(
                        (uintptr_t)mstate->dtms_probe->dtpr_func,
                        state, mstate));

          case DIF_VAR_PROBENAME:
                    ASSERT(mstate->dtms_present & DTRACE_MSTATE_PROBE);
                    return (dtrace_dif_varstr(
                        (uintptr_t)mstate->dtms_probe->dtpr_name,
                        state, mstate));

          case DIF_VAR_PID:
                    if (!dtrace_priv_proc(state))
                              return (0);

#ifdef illumos
                    /*
                     * Note that we are assuming that an unanchored probe is
                     * always due to a high-level interrupt.  (And we're assuming
                     * that there is only a single high level interrupt.)
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return (pid0.pid_id);

                    /*
                     * It is always safe to dereference one's own t_procp pointer:
                     * it always points to a valid, allocated proc structure.
                     * Further, it is always safe to dereference the p_pidp member
                     * of one's own proc structure.  (These are truisms becuase
                     * threads and processes don't clean up their own state --
                     * they leave that task to whomever reaps them.)
                     */
                    return ((uint64_t)curthread->t_procp->p_pidp->pid_id);
#else
                    return ((uint64_t)curproc->p_pid);
#endif

          case DIF_VAR_PPID:
                    if (!dtrace_priv_proc(state))
                              return (0);

#ifdef illumos
                    /*
                     * See comment in DIF_VAR_PID.
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return (pid0.pid_id);

                    /*
                     * It is always safe to dereference one's own t_procp pointer:
                     * it always points to a valid, allocated proc structure.
                     * (This is true because threads don't clean up their own
                     * state -- they leave that task to whomever reaps them.)
                     */
                    return ((uint64_t)curthread->t_procp->p_ppid);
#else
                    if (curproc->p_pid == proc0.p_pid)
                              return (curproc->p_pid);
                    else
                              return (curproc->p_pptr->p_pid);
#endif

          case DIF_VAR_TID:
#ifdef illumos
                    /*
                     * See comment in DIF_VAR_PID.
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return (0);
#endif

                    return ((uint64_t)curthread->t_tid);

          case DIF_VAR_EXECARGS: {
#ifdef __FreeBSD__
                    struct pargs *p_args = curthread->td_proc->p_args;

                    if (p_args == NULL)
                              return(0);

                    return (dtrace_dif_varstrz(
                        (uintptr_t) p_args->ar_args, p_args->ar_length, state, mstate));
#else
                    return 0;
#endif
          }

          case DIF_VAR_EXECNAME:
#ifdef illumos
                    if (!dtrace_priv_proc(state))
                              return (0);

                    /*
                     * See comment in DIF_VAR_PID.
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return ((uint64_t)(uintptr_t)p0.p_user.u_comm);

                    /*
                     * It is always safe to dereference one's own t_procp pointer:
                     * it always points to a valid, allocated proc structure.
                     * (This is true because threads don't clean up their own
                     * state -- they leave that task to whomever reaps them.)
                     */
                    return (dtrace_dif_varstr(
                        (uintptr_t)curthread->t_procp->p_user.u_comm,
                        state, mstate));
#else
                    return (dtrace_dif_varstr(
                        (uintptr_t) curproc->p_comm, state, mstate));
#endif

          case DIF_VAR_ZONENAME:
#ifdef illumos
                    if (!dtrace_priv_proc(state))
                              return (0);

                    /*
                     * See comment in DIF_VAR_PID.
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return ((uint64_t)(uintptr_t)p0.p_zone->zone_name);

                    /*
                     * It is always safe to dereference one's own t_procp pointer:
                     * it always points to a valid, allocated proc structure.
                     * (This is true because threads don't clean up their own
                     * state -- they leave that task to whomever reaps them.)
                     */
                    return (dtrace_dif_varstr(
                        (uintptr_t)curthread->t_procp->p_zone->zone_name,
                        state, mstate));
#else
                    return (0);
#endif

          case DIF_VAR_UID:
                    if (!dtrace_priv_proc(state))
                              return (0);

#ifdef illumos
                    /*
                     * See comment in DIF_VAR_PID.
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return ((uint64_t)p0.p_cred->cr_uid);

                    /*
                     * It is always safe to dereference one's own t_procp pointer:
                     * it always points to a valid, allocated proc structure.
                     * (This is true because threads don't clean up their own
                     * state -- they leave that task to whomever reaps them.)
                     *
                     * Additionally, it is safe to dereference one's own process
                     * credential, since this is never NULL after process birth.
                     */
                    return ((uint64_t)curthread->t_procp->p_cred->cr_uid);
#endif
#ifdef __FreeBSD__
                    return ((uint64_t)curthread->td_ucred->cr_uid);
#endif
#ifdef __NetBSD__
                    return ((uint64_t)kauth_cred_getuid(curthread->t_procp->p_cred));
#endif

          case DIF_VAR_GID:
                    if (!dtrace_priv_proc(state))
                              return (0);

#ifdef illumos
                    /*
                     * See comment in DIF_VAR_PID.
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return ((uint64_t)p0.p_cred->cr_gid);

                    /*
                     * It is always safe to dereference one's own t_procp pointer:
                     * it always points to a valid, allocated proc structure.
                     * (This is true because threads don't clean up their own
                     * state -- they leave that task to whomever reaps them.)
                     *
                     * Additionally, it is safe to dereference one's own process
                     * credential, since this is never NULL after process birth.
                     */
                    return ((uint64_t)curthread->t_procp->p_cred->cr_gid);
#endif
#ifdef __FreeBSD__
                    return ((uint64_t)curthread->td_ucred->cr_gid);
#endif
#ifdef __NetBSD__
                    return ((uint64_t)kauth_cred_getgid(curthread->t_procp->p_cred));
#endif

          case DIF_VAR_ERRNO: {
#ifdef illumos
                    klwp_t *lwp;
                    if (!dtrace_priv_proc(state))
                              return (0);

                    /*
                     * See comment in DIF_VAR_PID.
                     */
                    if (DTRACE_ANCHORED(mstate->dtms_probe) && CPU_ON_INTR(CPU))
                              return (0);

                    /*
                     * It is always safe to dereference one's own t_lwp pointer in
                     * the event that this pointer is non-NULL.  (This is true
                     * because threads and lwps don't clean up their own state --
                     * they leave that task to whomever reaps them.)
                     */
                    if ((lwp = curthread->t_lwp) == NULL)
                              return (0);

                    return ((uint64_t)lwp->lwp_errno);
#endif
#ifdef __FreeBSD__
                    return (curthread->td_errno);
#endif
#ifdef __NetBSD__
                    return 0; /* XXX TBD errno support at lwp level? */
#endif
          }
#ifndef illumos
          case DIF_VAR_CPU: {
                    return curcpu_id;
          }
#endif
          default:
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                    return (0);
          }
}


typedef enum dtrace_json_state {
          DTRACE_JSON_REST = 1,
          DTRACE_JSON_OBJECT,
          DTRACE_JSON_STRING,
          DTRACE_JSON_STRING_ESCAPE,
          DTRACE_JSON_STRING_ESCAPE_UNICODE,
          DTRACE_JSON_COLON,
          DTRACE_JSON_COMMA,
          DTRACE_JSON_VALUE,
          DTRACE_JSON_IDENTIFIER,
          DTRACE_JSON_NUMBER,
          DTRACE_JSON_NUMBER_FRAC,
          DTRACE_JSON_NUMBER_EXP,
          DTRACE_JSON_COLLECT_OBJECT
} dtrace_json_state_t;

/*
 * This function possesses just enough knowledge about JSON to extract a single
 * value from a JSON string and store it in the scratch buffer.  It is able
 * to extract nested object values, and members of arrays by index.
 *
 * elemlist is a list of JSON keys, stored as packed NUL-terminated strings, to
 * be looked up as we descend into the object tree.  e.g.
 *
 *    foo[0].bar.baz[32] --> "foo" NUL "0" NUL "bar" NUL "baz" NUL "32" NUL
 *       with nelems = 5.
 *
 * The run time of this function must be bounded above by strsize to limit the
 * amount of work done in probe context.  As such, it is implemented as a
 * simple state machine, reading one character at a time using safe loads
 * until we find the requested element, hit a parsing error or run off the
 * end of the object or string.
 *
 * As there is no way for a subroutine to return an error without interrupting
 * clause execution, we simply return NULL in the event of a missing key or any
 * other error condition.  Each NULL return in this function is commented with
 * the error condition it represents -- parsing or otherwise.
 *
 * The set of states for the state machine closely matches the JSON
 * specification (http://json.org/).  Briefly:
 *
 *   DTRACE_JSON_REST:
 *     Skip whitespace until we find either a top-level Object, moving
 *     to DTRACE_JSON_OBJECT; or an Array, moving to DTRACE_JSON_VALUE.
 *
 *   DTRACE_JSON_OBJECT:
 *     Locate the next key String in an Object.  Sets a flag to denote
 *     the next String as a key string and moves to DTRACE_JSON_STRING.
 *
 *   DTRACE_JSON_COLON:
 *     Skip whitespace until we find the colon that separates key Strings
 *     from their values.  Once found, move to DTRACE_JSON_VALUE.
 *
 *   DTRACE_JSON_VALUE:
 *     Detects the type of the next value (String, Number, Identifier, Object
 *     or Array) and routes to the states that process that type.  Here we also
 *     deal with the element selector list if we are requested to traverse down
 *     into the object tree.
 *
 *   DTRACE_JSON_COMMA:
 *     Skip whitespace until we find the comma that separates key-value pairs
 *     in Objects (returning to DTRACE_JSON_OBJECT) or values in Arrays
 *     (similarly DTRACE_JSON_VALUE).  All following literal value processing
 *     states return to this state at the end of their value, unless otherwise
 *     noted.
 *
 *   DTRACE_JSON_NUMBER, DTRACE_JSON_NUMBER_FRAC, DTRACE_JSON_NUMBER_EXP:
 *     Processes a Number literal from the JSON, including any exponent
 *     component that may be present.  Numbers are returned as strings, which
 *     may be passed to strtoll() if an integer is required.
 *
 *   DTRACE_JSON_IDENTIFIER:
 *     Processes a "true", "false" or "null" literal in the JSON.
 *
 *   DTRACE_JSON_STRING, DTRACE_JSON_STRING_ESCAPE,
 *   DTRACE_JSON_STRING_ESCAPE_UNICODE:
 *     Processes a String literal from the JSON, whether the String denotes
 *     a key, a value or part of a larger Object.  Handles all escape sequences
 *     present in the specification, including four-digit unicode characters,
 *     but merely includes the escape sequence without converting it to the
 *     actual escaped character.  If the String is flagged as a key, we
 *     move to DTRACE_JSON_COLON rather than DTRACE_JSON_COMMA.
 *
 *   DTRACE_JSON_COLLECT_OBJECT:
 *     This state collects an entire Object (or Array), correctly handling
 *     embedded strings.  If the full element selector list matches this nested
 *     object, we return the Object in full as a string.  If not, we use this
 *     state to skip to the next value at this level and continue processing.
 *
 * NOTE: This function uses various macros from strtolctype.h to manipulate
 * digit values, etc -- these have all been checked to ensure they make
 * no additional function calls.
 */
static char *
dtrace_json(uint64_t size, uintptr_t json, char *elemlist, int nelems,
    char *dest)
{
          dtrace_json_state_t state = DTRACE_JSON_REST;
          int64_t array_elem = INT64_MIN;
          int64_t array_pos = 0;
          uint8_t escape_unicount = 0;
          boolean_t string_is_key = B_FALSE;
          boolean_t collect_object = B_FALSE;
          boolean_t found_key = B_FALSE;
          boolean_t in_array = B_FALSE;
          uint32_t braces = 0, brackets = 0;
          char *elem = elemlist;
          char *dd = dest;
          uintptr_t cur;

          for (cur = json; cur < json + size; cur++) {
                    char cc = dtrace_load8(cur);
                    if (cc == '\0')
                              return (NULL);

                    switch (state) {
                    case DTRACE_JSON_REST:
                              if (isspace(cc))
                                        break;

                              if (cc == '{') {
                                        state = DTRACE_JSON_OBJECT;
                                        break;
                              }

                              if (cc == '[') {
                                        in_array = B_TRUE;
                                        array_pos = 0;
                                        array_elem = dtrace_strtoll(elem, 10, size);
                                        found_key = array_elem == 0 ? B_TRUE : B_FALSE;
                                        state = DTRACE_JSON_VALUE;
                                        break;
                              }

                              /*
                               * ERROR: expected to find a top-level object or array.
                               */
                              return (NULL);
                    case DTRACE_JSON_OBJECT:
                              if (isspace(cc))
                                        break;

                              if (cc == '"') {
                                        state = DTRACE_JSON_STRING;
                                        string_is_key = B_TRUE;
                                        break;
                              }

                              /*
                               * ERROR: either the object did not start with a key
                               * string, or we've run off the end of the object
                               * without finding the requested key.
                               */
                              return (NULL);
                    case DTRACE_JSON_STRING:
                              if (cc == '\\') {
                                        *dd++ = '\\';
                                        state = DTRACE_JSON_STRING_ESCAPE;
                                        break;
                              }

                              if (cc == '"') {
                                        if (collect_object) {
                                                  /*
                                                   * We don't reset the dest here, as
                                                   * the string is part of a larger
                                                   * object being collected.
                                                   */
                                                  *dd++ = cc;
                                                  collect_object = B_FALSE;
                                                  state = DTRACE_JSON_COLLECT_OBJECT;
                                                  break;
                                        }
                                        *dd = '\0';
                                        dd = dest; /* reset string buffer */
                                        if (string_is_key) {
                                                  if (dtrace_strncmp(dest, elem,
                                                      size) == 0)
                                                            found_key = B_TRUE;
                                        } else if (found_key) {
                                                  if (nelems > 1) {
                                                            /*
                                                             * We expected an object, not
                                                             * this string.
                                                             */
                                                            return (NULL);
                                                  }
                                                  return (dest);
                                        }
                                        state = string_is_key ? DTRACE_JSON_COLON :
                                            DTRACE_JSON_COMMA;
                                        string_is_key = B_FALSE;
                                        break;
                              }

                              *dd++ = cc;
                              break;
                    case DTRACE_JSON_STRING_ESCAPE:
                              *dd++ = cc;
                              if (cc == 'u') {
                                        escape_unicount = 0;
                                        state = DTRACE_JSON_STRING_ESCAPE_UNICODE;
                              } else {
                                        state = DTRACE_JSON_STRING;
                              }
                              break;
                    case DTRACE_JSON_STRING_ESCAPE_UNICODE:
                              if (!isxdigit(cc)) {
                                        /*
                                         * ERROR: invalid unicode escape, expected
                                         * four valid hexidecimal digits.
                                         */
                                        return (NULL);
                              }

                              *dd++ = cc;
                              if (++escape_unicount == 4)
                                        state = DTRACE_JSON_STRING;
                              break;
                    case DTRACE_JSON_COLON:
                              if (isspace(cc))
                                        break;

                              if (cc == ':') {
                                        state = DTRACE_JSON_VALUE;
                                        break;
                              }

                              /*
                               * ERROR: expected a colon.
                               */
                              return (NULL);
                    case DTRACE_JSON_COMMA:
                              if (isspace(cc))
                                        break;

                              if (cc == ',') {
                                        if (in_array) {
                                                  state = DTRACE_JSON_VALUE;
                                                  if (++array_pos == array_elem)
                                                            found_key = B_TRUE;
                                        } else {
                                                  state = DTRACE_JSON_OBJECT;
                                        }
                                        break;
                              }

                              /*
                               * ERROR: either we hit an unexpected character, or
                               * we reached the end of the object or array without
                               * finding the requested key.
                               */
                              return (NULL);
                    case DTRACE_JSON_IDENTIFIER:
                              if (islower(cc)) {
                                        *dd++ = cc;
                                        break;
                              }

                              *dd = '\0';
                              dd = dest; /* reset string buffer */

                              if (dtrace_strncmp(dest, "true", 5) == 0 ||
                                  dtrace_strncmp(dest, "false", 6) == 0 ||
                                  dtrace_strncmp(dest, "null", 5) == 0) {
                                        if (found_key) {
                                                  if (nelems > 1) {
                                                            /*
                                                             * ERROR: We expected an object,
                                                             * not this identifier.
                                                             */
                                                            return (NULL);
                                                  }
                                                  return (dest);
                                        } else {
                                                  cur--;
                                                  state = DTRACE_JSON_COMMA;
                                                  break;
                                        }
                              }

                              /*
                               * ERROR: we did not recognise the identifier as one
                               * of those in the JSON specification.
                               */
                              return (NULL);
                    case DTRACE_JSON_NUMBER:
                              if (cc == '.') {
                                        *dd++ = cc;
                                        state = DTRACE_JSON_NUMBER_FRAC;
                                        break;
                              }

                              if (cc == 'x' || cc == 'X') {
                                        /*
                                         * ERROR: specification explicitly excludes
                                         * hexidecimal or octal numbers.
                                         */
                                        return (NULL);
                              }

                              /* FALLTHRU */
                    case DTRACE_JSON_NUMBER_FRAC:
                              if (cc == 'e' || cc == 'E') {
                                        *dd++ = cc;
                                        state = DTRACE_JSON_NUMBER_EXP;
                                        break;
                              }

                              if (cc == '+' || cc == '-') {
                                        /*
                                         * ERROR: expect sign as part of exponent only.
                                         */
                                        return (NULL);
                              }
                              /* FALLTHRU */
                    case DTRACE_JSON_NUMBER_EXP:
                              if (isdigit(cc) || cc == '+' || cc == '-') {
                                        *dd++ = cc;
                                        break;
                              }

                              *dd = '\0';
                              dd = dest; /* reset string buffer */
                              if (found_key) {
                                        if (nelems > 1) {
                                                  /*
                                                   * ERROR: We expected an object, not
                                                   * this number.
                                                   */
                                                  return (NULL);
                                        }
                                        return (dest);
                              }

                              cur--;
                              state = DTRACE_JSON_COMMA;
                              break;
                    case DTRACE_JSON_VALUE:
                              if (isspace(cc))
                                        break;

                              if (cc == '{' || cc == '[') {
                                        if (nelems > 1 && found_key) {
                                                  in_array = cc == '[' ? B_TRUE : B_FALSE;
                                                  /*
                                                   * If our element selector directs us
                                                   * to descend into this nested object,
                                                   * then move to the next selector
                                                   * element in the list and restart the
                                                   * state machine.
                                                   */
                                                  while (*elem != '\0')
                                                            elem++;
                                                  elem++; /* skip the inter-element NUL */
                                                  nelems--;
                                                  dd = dest;
                                                  if (in_array) {
                                                            state = DTRACE_JSON_VALUE;
                                                            array_pos = 0;
                                                            array_elem = dtrace_strtoll(
                                                                elem, 10, size);
                                                            found_key = array_elem == 0 ?
                                                                B_TRUE : B_FALSE;
                                                  } else {
                                                            found_key = B_FALSE;
                                                            state = DTRACE_JSON_OBJECT;
                                                  }
                                                  break;
                                        }

                                        /*
                                         * Otherwise, we wish to either skip this
                                         * nested object or return it in full.
                                         */
                                        if (cc == '[')
                                                  brackets = 1;
                                        else
                                                  braces = 1;
                                        *dd++ = cc;
                                        state = DTRACE_JSON_COLLECT_OBJECT;
                                        break;
                              }

                              if (cc == '"') {
                                        state = DTRACE_JSON_STRING;
                                        break;
                              }

                              if (islower(cc)) {
                                        /*
                                         * Here we deal with true, false and null.
                                         */
                                        *dd++ = cc;
                                        state = DTRACE_JSON_IDENTIFIER;
                                        break;
                              }

                              if (cc == '-' || isdigit(cc)) {
                                        *dd++ = cc;
                                        state = DTRACE_JSON_NUMBER;
                                        break;
                              }

                              /*
                               * ERROR: unexpected character at start of value.
                               */
                              return (NULL);
                    case DTRACE_JSON_COLLECT_OBJECT:
                              if (cc == '\0')
                                        /*
                                         * ERROR: unexpected end of input.
                                         */
                                        return (NULL);

                              *dd++ = cc;
                              if (cc == '"') {
                                        collect_object = B_TRUE;
                                        state = DTRACE_JSON_STRING;
                                        break;
                              }

                              if (cc == ']') {
                                        if (brackets-- == 0) {
                                                  /*
                                                   * ERROR: unbalanced brackets.
                                                   */
                                                  return (NULL);
                                        }
                              } else if (cc == '}') {
                                        if (braces-- == 0) {
                                                  /*
                                                   * ERROR: unbalanced braces.
                                                   */
                                                  return (NULL);
                                        }
                              } else if (cc == '{') {
                                        braces++;
                              } else if (cc == '[') {
                                        brackets++;
                              }

                              if (brackets == 0 && braces == 0) {
                                        if (found_key) {
                                                  *dd = '\0';
                                                  return (dest);
                                        }
                                        dd = dest; /* reset string buffer */
                                        state = DTRACE_JSON_COMMA;
                              }
                              break;
                    }
          }
          return (NULL);
}

/*
 * Emulate the execution of DTrace ID subroutines invoked by the call opcode.
 * Notice that we don't bother validating the proper number of arguments or
 * their types in the tuple stack.  This isn't needed because all argument
 * interpretation is safe because of our load safety -- the worst that can
 * happen is that a bogus program can obtain bogus results.
 */
static void
dtrace_dif_subr(uint_t subr, uint_t rd, uint64_t *regs,
    dtrace_key_t *tupregs, int nargs,
    dtrace_mstate_t *mstate, dtrace_state_t *state)
{
          volatile uint16_t *flags = &cpu_core[curcpu_id].cpuc_dtrace_flags;
          volatile uintptr_t *illval = &cpu_core[curcpu_id].cpuc_dtrace_illval;
          dtrace_vstate_t *vstate = &state->dts_vstate;

#ifdef illumos
          union {
                    mutex_impl_t mi;
                    uint64_t mx;
          } m;

          union {
                    krwlock_t ri;
                    uintptr_t rw;
          } r;
#endif
#ifdef __FreeBSD__
          struct thread *lowner;
          union {
                    struct lock_object *li;
                    uintptr_t lx;
          } l;
#endif
#ifdef __NetBSD__
          union {
                    kmutex_t mi;
                    uint64_t mx;
          } m;

          union {
                    krwlock_t ri;
                    uintptr_t rw;
          } r;
#endif

          switch (subr) {
          case DIF_SUBR_RAND:
                    regs[rd] = dtrace_xoroshiro128_plus_next(
                        state->dts_rstate[curcpu_id]);
                    break;

#ifdef illumos
          case DIF_SUBR_MUTEX_OWNED:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    if (MUTEX_TYPE_ADAPTIVE(&m.mi))
                              regs[rd] = MUTEX_OWNER(&m.mi) != MUTEX_NO_OWNER;
                    else
                              regs[rd] = LOCK_HELD(&m.mi.m_spin.m_spinlock);
                    break;

          case DIF_SUBR_MUTEX_OWNER:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    if (MUTEX_TYPE_ADAPTIVE(&m.mi) &&
                        MUTEX_OWNER(&m.mi) != MUTEX_NO_OWNER)
                              regs[rd] = (uintptr_t)MUTEX_OWNER(&m.mi);
                    else
                              regs[rd] = 0;
                    break;

          case DIF_SUBR_MUTEX_TYPE_ADAPTIVE:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    regs[rd] = MUTEX_TYPE_ADAPTIVE(&m.mi);
                    break;

          case DIF_SUBR_MUTEX_TYPE_SPIN:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    regs[rd] = MUTEX_TYPE_SPIN(&m.mi);
                    break;

          case DIF_SUBR_RW_READ_HELD: {
                    uintptr_t tmp;

                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                    regs[rd] = _RW_READ_HELD(&r.ri, tmp);
                    break;
          }

          case DIF_SUBR_RW_WRITE_HELD:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (krwlock_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                    regs[rd] = _RW_WRITE_HELD(&r.ri);
                    break;

          case DIF_SUBR_RW_ISWRITER:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (krwlock_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                    regs[rd] = _RW_ISWRITER(&r.ri);
                    break;

#endif /* illumos */
#ifdef __FreeBSD__
          case DIF_SUBR_MUTEX_OWNED:
                    if (!dtrace_canload(tupregs[0].dttk_value,
                              sizeof (struct lock_object), mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    break;

          case DIF_SUBR_MUTEX_OWNER:
                    if (!dtrace_canload(tupregs[0].dttk_value,
                              sizeof (struct lock_object), mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    regs[rd] = (uintptr_t)lowner;
                    break;

          case DIF_SUBR_MUTEX_TYPE_ADAPTIVE:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (struct mtx),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    regs[rd] = (LOCK_CLASS(l.li)->lc_flags & LC_SLEEPLOCK) != 0;
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    break;

          case DIF_SUBR_MUTEX_TYPE_SPIN:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (struct mtx),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    regs[rd] = (LOCK_CLASS(l.li)->lc_flags & LC_SPINLOCK) != 0;
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    break;

          case DIF_SUBR_RW_READ_HELD:
          case DIF_SUBR_SX_SHARED_HELD:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    l.lx = dtrace_loadptr((uintptr_t)&tupregs[0].dttk_value);
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner) &&
                        lowner == NULL;
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    break;

          case DIF_SUBR_RW_WRITE_HELD:
          case DIF_SUBR_SX_EXCLUSIVE_HELD:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    l.lx = dtrace_loadptr(tupregs[0].dttk_value);
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    regs[rd] = LOCK_CLASS(l.li)->lc_owner(l.li, &lowner) &&
                        lowner != NULL;
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    break;

          case DIF_SUBR_RW_ISWRITER:
          case DIF_SUBR_SX_ISEXCLUSIVE:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (uintptr_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    l.lx = dtrace_loadptr(tupregs[0].dttk_value);
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    LOCK_CLASS(l.li)->lc_owner(l.li, &lowner);
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    regs[rd] = (lowner == curthread);
                    break;

#endif /* __FreeBSD__ */
#ifdef __NetBSD__
          case DIF_SUBR_MUTEX_OWNED:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    if (MUTEX_TYPE_ADAPTIVE(&m.mi))
                              regs[rd] = MUTEX_OWNER(&m.mi) != MUTEX_NO_OWNER;
                    else
                              regs[rd] = __SIMPLELOCK_LOCKED_P(&m.mi.mtx_lock);
                    break;

          case DIF_SUBR_MUTEX_OWNER:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    if (MUTEX_TYPE_ADAPTIVE(&m.mi) &&
                        MUTEX_OWNER(&m.mi) != MUTEX_NO_OWNER)
                              regs[rd] = (uintptr_t)MUTEX_OWNER(&m.mi);
                    else
                              regs[rd] = 0;
                    break;

          case DIF_SUBR_MUTEX_TYPE_ADAPTIVE:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    regs[rd] = MUTEX_TYPE_ADAPTIVE(&m.mi);
                    break;

          case DIF_SUBR_MUTEX_TYPE_SPIN:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (kmutex_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    m.mx = dtrace_load64(tupregs[0].dttk_value);
                    regs[rd] = MUTEX_TYPE_SPIN(&m.mi);
                    break;

          case DIF_SUBR_RW_READ_HELD: {
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (krwlock_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                    regs[rd] = _RW_READ_HELD(&r.ri);
                    break;
          }

          case DIF_SUBR_RW_WRITE_HELD:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (krwlock_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                    regs[rd] = _RW_WRITE_HELD(&r.ri);
                    break;

          case DIF_SUBR_RW_ISWRITER:
                    if (!dtrace_canload(tupregs[0].dttk_value, sizeof (krwlock_t),
                        mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    r.rw = dtrace_loadptr(tupregs[0].dttk_value);
                    regs[rd] = _RW_ISWRITER(&r.ri);
                    break;

#endif /* __NetBSD__ */

          case DIF_SUBR_BCOPY: {
                    /*
                     * We need to be sure that the destination is in the scratch
                     * region -- no other region is allowed.
                     */
                    uintptr_t src = tupregs[0].dttk_value;
                    uintptr_t dest = tupregs[1].dttk_value;
                    size_t size = tupregs[2].dttk_value;

                    if (!dtrace_inscratch(dest, size, mstate)) {
                              *flags |= CPU_DTRACE_BADADDR;
                              *illval = regs[rd];
                              break;
                    }

                    if (!dtrace_canload(src, size, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    dtrace_bcopy((void *)src, (void *)dest, size);
                    break;
          }

          case DIF_SUBR_ALLOCA:
          case DIF_SUBR_COPYIN: {
                    uintptr_t dest = P2ROUNDUP(mstate->dtms_scratch_ptr, 8);
                    uint64_t size =
                        tupregs[subr == DIF_SUBR_ALLOCA ? 0 : 1].dttk_value;
                    size_t scratch_size = (dest - mstate->dtms_scratch_ptr) + size;

                    /*
                     * This action doesn't require any credential checks since
                     * probes will not activate in user contexts to which the
                     * enabling user does not have permissions.
                     */

                    /*
                     * Rounding up the user allocation size could have overflowed
                     * a large, bogus allocation (like -1ULL) to 0.
                     */
                    if (scratch_size < size ||
                        !DTRACE_INSCRATCH(mstate, scratch_size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    if (subr == DIF_SUBR_COPYIN) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              dtrace_copyin(tupregs[0].dttk_value, dest, size, flags);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    }

                    mstate->dtms_scratch_ptr += scratch_size;
                    regs[rd] = dest;
                    break;
          }

          case DIF_SUBR_COPYINTO: {
                    uint64_t size = tupregs[1].dttk_value;
                    uintptr_t dest = tupregs[2].dttk_value;

                    /*
                     * This action doesn't require any credential checks since
                     * probes will not activate in user contexts to which the
                     * enabling user does not have permissions.
                     */
                    if (!dtrace_inscratch(dest, size, mstate)) {
                              *flags |= CPU_DTRACE_BADADDR;
                              *illval = regs[rd];
                              break;
                    }

                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    dtrace_copyin(tupregs[0].dttk_value, dest, size, flags);
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    break;
          }

          case DIF_SUBR_COPYINSTR: {
                    uintptr_t dest = mstate->dtms_scratch_ptr;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];

                    if (nargs > 1 && tupregs[1].dttk_value < size)
                              size = tupregs[1].dttk_value + 1;

                    /*
                     * This action doesn't require any credential checks since
                     * probes will not activate in user contexts to which the
                     * enabling user does not have permissions.
                     */
                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                    dtrace_copyinstr(tupregs[0].dttk_value, dest, size, flags);
                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);

                    ((char *)dest)[size - 1] = '\0';
                    mstate->dtms_scratch_ptr += size;
                    regs[rd] = dest;
                    break;
          }

#ifdef illumos
          case DIF_SUBR_MSGSIZE:
          case DIF_SUBR_MSGDSIZE: {
                    uintptr_t baddr = tupregs[0].dttk_value, daddr;
                    uintptr_t wptr, rptr;
                    size_t count = 0;
                    int cont = 0;

                    while (baddr != 0 && !(*flags & CPU_DTRACE_FAULT)) {

                              if (!dtrace_canload(baddr, sizeof (mblk_t), mstate,
                                  vstate)) {
                                        regs[rd] = 0;
                                        break;
                              }

                              wptr = dtrace_loadptr(baddr +
                                  offsetof(mblk_t, b_wptr));

                              rptr = dtrace_loadptr(baddr +
                                  offsetof(mblk_t, b_rptr));

                              if (wptr < rptr) {
                                        *flags |= CPU_DTRACE_BADADDR;
                                        *illval = tupregs[0].dttk_value;
                                        break;
                              }

                              daddr = dtrace_loadptr(baddr +
                                  offsetof(mblk_t, b_datap));

                              baddr = dtrace_loadptr(baddr +
                                  offsetof(mblk_t, b_cont));

                              /*
                               * We want to prevent against denial-of-service here,
                               * so we're only going to search the list for
                               * dtrace_msgdsize_max mblks.
                               */
                              if (cont++ > dtrace_msgdsize_max) {
                                        *flags |= CPU_DTRACE_ILLOP;
                                        break;
                              }

                              if (subr == DIF_SUBR_MSGDSIZE) {
                                        if (dtrace_load8(daddr +
                                            offsetof(dblk_t, db_type)) != M_DATA)
                                                  continue;
                              }

                              count += wptr - rptr;
                    }

                    if (!(*flags & CPU_DTRACE_FAULT))
                              regs[rd] = count;

                    break;
          }
#endif

          case DIF_SUBR_PROGENYOF: {
                    pid_t pid = tupregs[0].dttk_value;
                    proc_t *p;
                    int rval = 0;

                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);

                    for (p = curthread->t_procp; p != NULL; p = p->p_parent) {
#ifdef illumos
                              if (p->p_pidp->pid_id == pid) {
#else
                              if (p->p_pid == pid) {
#endif
                                        rval = 1;
                                        break;
                              }
                    }

                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);

                    regs[rd] = rval;
                    break;
          }

          case DIF_SUBR_SPECULATION:
                    regs[rd] = dtrace_speculation(state);
                    break;

          case DIF_SUBR_COPYOUT: {
                    uintptr_t kaddr = tupregs[0].dttk_value;
                    uintptr_t uaddr = tupregs[1].dttk_value;
                    uint64_t size = tupregs[2].dttk_value;

                    if (!dtrace_destructive_disallow &&
                        dtrace_priv_proc_control(state) &&
                        !dtrace_istoxic(kaddr, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              dtrace_copyout(kaddr, uaddr, size, flags);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    }
                    break;
          }

          case DIF_SUBR_COPYOUTSTR: {
                    uintptr_t kaddr = tupregs[0].dttk_value;
                    uintptr_t uaddr = tupregs[1].dttk_value;
                    uint64_t size = tupregs[2].dttk_value;
                    size_t lim;

                    if (!dtrace_destructive_disallow &&
                        dtrace_priv_proc_control(state) &&
                        !dtrace_istoxic(kaddr, size) &&
                        dtrace_strcanload(kaddr, size, &lim, mstate, vstate)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              dtrace_copyoutstr(kaddr, uaddr, lim, flags);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                    }
                    break;
          }

          case DIF_SUBR_STRLEN: {
                    size_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    uintptr_t addr = (uintptr_t)tupregs[0].dttk_value;
                    size_t lim;

                    if (!dtrace_strcanload(addr, size, &lim, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    regs[rd] = dtrace_strlen((char *)addr, lim);
                    break;
          }

          case DIF_SUBR_STRCHR:
          case DIF_SUBR_STRRCHR: {
                    /*
                     * We're going to iterate over the string looking for the
                     * specified character.  We will iterate until we have reached
                     * the string length or we have found the character.  If this
                     * is DIF_SUBR_STRRCHR, we will look for the last occurrence
                     * of the specified character instead of the first.
                     */
                    uintptr_t addr = tupregs[0].dttk_value;
                    uintptr_t addr_limit;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    size_t lim;
                    char c, target = (char)tupregs[1].dttk_value;

                    if (!dtrace_strcanload(addr, size, &lim, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    addr_limit = addr + lim;

                    for (regs[rd] = 0; addr < addr_limit; addr++) {
                              if ((c = dtrace_load8(addr)) == target) {
                                        regs[rd] = addr;

                                        if (subr == DIF_SUBR_STRCHR)
                                                  break;
                              }

                              if (c == '\0')
                                        break;
                    }
                    break;
          }

          case DIF_SUBR_STRSTR:
          case DIF_SUBR_INDEX:
          case DIF_SUBR_RINDEX: {
                    /*
                     * We're going to iterate over the string looking for the
                     * specified string.  We will iterate until we have reached
                     * the string length or we have found the string.  (Yes, this
                     * is done in the most naive way possible -- but considering
                     * that the string we're searching for is likely to be
                     * relatively short, the complexity of Rabin-Karp or similar
                     * hardly seems merited.)
                     */
                    char *addr = (char *)(uintptr_t)tupregs[0].dttk_value;
                    char *substr = (char *)(uintptr_t)tupregs[1].dttk_value;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    size_t len = dtrace_strlen(addr, size);
                    size_t sublen = dtrace_strlen(substr, size);
                    char *limit = addr + len, *orig = addr;
                    int notfound = subr == DIF_SUBR_STRSTR ? 0 : -1;
                    int inc = 1;

                    regs[rd] = notfound;

                    if (!dtrace_canload((uintptr_t)addr, len + 1, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    if (!dtrace_canload((uintptr_t)substr, sublen + 1, mstate,
                        vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    /*
                     * strstr() and index()/rindex() have similar semantics if
                     * both strings are the empty string: strstr() returns a
                     * pointer to the (empty) string, and index() and rindex()
                     * both return index 0 (regardless of any position argument).
                     */
                    if (sublen == 0 && len == 0) {
                              if (subr == DIF_SUBR_STRSTR)
                                        regs[rd] = (uintptr_t)addr;
                              else
                                        regs[rd] = 0;
                              break;
                    }

                    if (subr != DIF_SUBR_STRSTR) {
                              if (subr == DIF_SUBR_RINDEX) {
                                        limit = orig - 1;
                                        addr += len;
                                        inc = -1;
                              }

                              /*
                               * Both index() and rindex() take an optional position
                               * argument that denotes the starting position.
                               */
                              if (nargs == 3) {
                                        int64_t pos = (int64_t)tupregs[2].dttk_value;

                                        /*
                                         * If the position argument to index() is
                                         * negative, Perl implicitly clamps it at
                                         * zero.  This semantic is a little surprising
                                         * given the special meaning of negative
                                         * positions to similar Perl functions like
                                         * substr(), but it appears to reflect a
                                         * notion that index() can start from a
                                         * negative index and increment its way up to
                                         * the string.  Given this notion, Perl's
                                         * rindex() is at least self-consistent in
                                         * that it implicitly clamps positions greater
                                         * than the string length to be the string
                                         * length.  Where Perl completely loses
                                         * coherence, however, is when the specified
                                         * substring is the empty string ("").  In
                                         * this case, even if the position is
                                         * negative, rindex() returns 0 -- and even if
                                         * the position is greater than the length,
                                         * index() returns the string length.  These
                                         * semantics violate the notion that index()
                                         * should never return a value less than the
                                         * specified position and that rindex() should
                                         * never return a value greater than the
                                         * specified position.  (One assumes that
                                         * these semantics are artifacts of Perl's
                                         * implementation and not the results of
                                         * deliberate design -- it beggars belief that
                                         * even Larry Wall could desire such oddness.)
                                         * While in the abstract one would wish for
                                         * consistent position semantics across
                                         * substr(), index() and rindex() -- or at the
                                         * very least self-consistent position
                                         * semantics for index() and rindex() -- we
                                         * instead opt to keep with the extant Perl
                                         * semantics, in all their broken glory.  (Do
                                         * we have more desire to maintain Perl's
                                         * semantics than Perl does?  Probably.)
                                         */
                                        if (subr == DIF_SUBR_RINDEX) {
                                                  if (pos < 0) {
                                                            if (sublen == 0)
                                                                      regs[rd] = 0;
                                                            break;
                                                  }

                                                  if (pos > len)
                                                            pos = len;
                                        } else {
                                                  if (pos < 0)
                                                            pos = 0;

                                                  if (pos >= len) {
                                                            if (sublen == 0)
                                                                      regs[rd] = len;
                                                            break;
                                                  }
                                        }

                                        addr = orig + pos;
                              }
                    }

                    for (regs[rd] = notfound; addr != limit; addr += inc) {
                              if (dtrace_strncmp(addr, substr, sublen) == 0) {
                                        if (subr != DIF_SUBR_STRSTR) {
                                                  /*
                                                   * As D index() and rindex() are
                                                   * modeled on Perl (and not on awk),
                                                   * we return a zero-based (and not a
                                                   * one-based) index.  (For you Perl
                                                   * weenies: no, we're not going to add
                                                   * $[ -- and shouldn't you be at a con
                                                   * or something?)
                                                   */
                                                  regs[rd] = (uintptr_t)(addr - orig);
                                                  break;
                                        }

                                        ASSERT(subr == DIF_SUBR_STRSTR);
                                        regs[rd] = (uintptr_t)addr;
                                        break;
                              }
                    }

                    break;
          }

          case DIF_SUBR_STRTOK: {
                    uintptr_t addr = tupregs[0].dttk_value;
                    uintptr_t tokaddr = tupregs[1].dttk_value;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    uintptr_t limit, toklimit;
                    size_t clim;
                    uint8_t c = 0, tokmap[32];     /* 256 / 8 */
                    char *dest = (char *)mstate->dtms_scratch_ptr;
                    int i;

                    /*
                     * Check both the token buffer and (later) the input buffer,
                     * since both could be non-scratch addresses.
                     */
                    if (!dtrace_strcanload(tokaddr, size, &clim, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }
                    toklimit = tokaddr + clim;

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    if (addr == 0) {
                              /*
                               * If the address specified is NULL, we use our saved
                               * strtok pointer from the mstate.  Note that this
                               * means that the saved strtok pointer is _only_
                               * valid within multiple enablings of the same probe --
                               * it behaves like an implicit clause-local variable.
                               */
                              addr = mstate->dtms_strtok;
                              limit = mstate->dtms_strtok_limit;
                    } else {
                              /*
                               * If the user-specified address is non-NULL we must
                               * access check it.  This is the only time we have
                               * a chance to do so, since this address may reside
                               * in the string table of this clause-- future calls
                               * (when we fetch addr from mstate->dtms_strtok)
                               * would fail this access check.
                               */
                              if (!dtrace_strcanload(addr, size, &clim, mstate,
                                  vstate)) {
                                        regs[rd] = 0;
                                        break;
                              }
                              limit = addr + clim;
                    }

                    /*
                     * First, zero the token map, and then process the token
                     * string -- setting a bit in the map for every character
                     * found in the token string.
                     */
                    for (i = 0; i < sizeof (tokmap); i++)
                              tokmap[i] = 0;

                    for (; tokaddr < toklimit; tokaddr++) {
                              if ((c = dtrace_load8(tokaddr)) == '\0')
                                        break;

                              ASSERT((c >> 3) < sizeof (tokmap));
                              tokmap[c >> 3] |= (1 << (c & 0x7));
                    }

                    for (; addr < limit; addr++) {
                              /*
                               * We're looking for a character that is _not_
                               * contained in the token string.
                               */
                              if ((c = dtrace_load8(addr)) == '\0')
                                        break;

                              if (!(tokmap[c >> 3] & (1 << (c & 0x7))))
                                        break;
                    }

                    if (c == '\0') {
                              /*
                               * We reached the end of the string without finding
                               * any character that was not in the token string.
                               * We return NULL in this case, and we set the saved
                               * address to NULL as well.
                               */
                              regs[rd] = 0;
                              mstate->dtms_strtok = 0;
                              mstate->dtms_strtok_limit = 0;
                              break;
                    }

                    /*
                     * From here on, we're copying into the destination string.
                     */
                    for (i = 0; addr < limit && i < size - 1; addr++) {
                              if ((c = dtrace_load8(addr)) == '\0')
                                        break;

                              if (tokmap[c >> 3] & (1 << (c & 0x7)))
                                        break;

                              ASSERT(i < size);
                              dest[i++] = c;
                    }

                    ASSERT(i < size);
                    dest[i] = '\0';
                    regs[rd] = (uintptr_t)dest;
                    mstate->dtms_scratch_ptr += size;
                    mstate->dtms_strtok = addr;
                    mstate->dtms_strtok_limit = limit;
                    break;
          }

          case DIF_SUBR_SUBSTR: {
                    uintptr_t s = tupregs[0].dttk_value;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    char *d = (char *)mstate->dtms_scratch_ptr;
                    int64_t index = (int64_t)tupregs[1].dttk_value;
                    int64_t remaining = (int64_t)tupregs[2].dttk_value;
                    size_t len = dtrace_strlen((char *)s, size);
                    int64_t i;

                    if (!dtrace_canload(s, len + 1, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    if (nargs <= 2)
                              remaining = (int64_t)size;

                    if (index < 0) {
                              index += len;

                              if (index < 0 && index + remaining > 0) {
                                        remaining += index;
                                        index = 0;
                              }
                    }

                    if (index >= len || index < 0) {
                              remaining = 0;
                    } else if (remaining < 0) {
                              remaining += len - index;
                    } else if (index + remaining > size) {
                              remaining = size - index;
                    }

                    for (i = 0; i < remaining; i++) {
                              if ((d[i] = dtrace_load8(s + index + i)) == '\0')
                                        break;
                    }

                    d[i] = '\0';

                    mstate->dtms_scratch_ptr += size;
                    regs[rd] = (uintptr_t)d;
                    break;
          }

          case DIF_SUBR_JSON: {
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    uintptr_t json = tupregs[0].dttk_value;
                    size_t jsonlen = dtrace_strlen((char *)json, size);
                    uintptr_t elem = tupregs[1].dttk_value;
                    size_t elemlen = dtrace_strlen((char *)elem, size);

                    char *dest = (char *)mstate->dtms_scratch_ptr;
                    char *elemlist = (char *)mstate->dtms_scratch_ptr + jsonlen + 1;
                    char *ee = elemlist;
                    int nelems = 1;
                    uintptr_t cur;

                    if (!dtrace_canload(json, jsonlen + 1, mstate, vstate) ||
                        !dtrace_canload(elem, elemlen + 1, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    if (!DTRACE_INSCRATCH(mstate, jsonlen + 1 + elemlen + 1)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    /*
                     * Read the element selector and split it up into a packed list
                     * of strings.
                     */
                    for (cur = elem; cur < elem + elemlen; cur++) {
                              char cc = dtrace_load8(cur);

                              if (cur == elem && cc == '[') {
                                        /*
                                         * If the first element selector key is
                                         * actually an array index then ignore the
                                         * bracket.
                                         */
                                        continue;
                              }

                              if (cc == ']')
                                        continue;

                              if (cc == '.' || cc == '[') {
                                        nelems++;
                                        cc = '\0';
                              }

                              *ee++ = cc;
                    }
                    *ee++ = '\0';

                    if ((regs[rd] = (uintptr_t)dtrace_json(size, json, elemlist,
                        nelems, dest)) != 0)
                              mstate->dtms_scratch_ptr += jsonlen + 1;
                    break;
          }

          case DIF_SUBR_TOUPPER:
          case DIF_SUBR_TOLOWER: {
                    uintptr_t s = tupregs[0].dttk_value;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    char *dest = (char *)mstate->dtms_scratch_ptr, c;
                    size_t len = dtrace_strlen((char *)s, size);
                    char lower, upper, convert;
                    int64_t i;

                    if (subr == DIF_SUBR_TOUPPER) {
                              lower = 'a';
                              upper = 'z';
                              convert = 'A';
                    } else {
                              lower = 'A';
                              upper = 'Z';
                              convert = 'a';
                    }

                    if (!dtrace_canload(s, len + 1, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    for (i = 0; i < size - 1; i++) {
                              if ((c = dtrace_load8(s + i)) == '\0')
                                        break;

                              if (c >= lower && c <= upper)
                                        c = convert + (c - lower);

                              dest[i] = c;
                    }

                    ASSERT(i < size);
                    dest[i] = '\0';
                    regs[rd] = (uintptr_t)dest;
                    mstate->dtms_scratch_ptr += size;
                    break;
          }

#ifdef illumos
          case DIF_SUBR_GETMAJOR:
#ifdef _LP64
                    regs[rd] = (tupregs[0].dttk_value >> NBITSMINOR64) & MAXMAJ64;
#else
                    regs[rd] = (tupregs[0].dttk_value >> NBITSMINOR) & MAXMAJ;
#endif
                    break;

          case DIF_SUBR_GETMINOR:
#ifdef _LP64
                    regs[rd] = tupregs[0].dttk_value & MAXMIN64;
#else
                    regs[rd] = tupregs[0].dttk_value & MAXMIN;
#endif
                    break;

          case DIF_SUBR_DDI_PATHNAME: {
                    /*
                     * This one is a galactic mess.  We are going to roughly
                     * emulate ddi_pathname(), but it's made more complicated
                     * by the fact that we (a) want to include the minor name and
                     * (b) must proceed iteratively instead of recursively.
                     */
                    uintptr_t dest = mstate->dtms_scratch_ptr;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    char *start = (char *)dest, *end = start + size - 1;
                    uintptr_t daddr = tupregs[0].dttk_value;
                    int64_t minor = (int64_t)tupregs[1].dttk_value;
                    char *s;
                    int i, len, depth = 0;

                    /*
                     * Due to all the pointer jumping we do and context we must
                     * rely upon, we just mandate that the user must have kernel
                     * read privileges to use this routine.
                     */
                    if ((mstate->dtms_access & DTRACE_ACCESS_KERNEL) == 0) {
                              *flags |= CPU_DTRACE_KPRIV;
                              *illval = daddr;
                              regs[rd] = 0;
                    }

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    *end = '\0';

                    /*
                     * We want to have a name for the minor.  In order to do this,
                     * we need to walk the minor list from the devinfo.  We want
                     * to be sure that we don't infinitely walk a circular list,
                     * so we check for circularity by sending a scout pointer
                     * ahead two elements for every element that we iterate over;
                     * if the list is circular, these will ultimately point to the
                     * same element.  You may recognize this little trick as the
                     * answer to a stupid interview question -- one that always
                     * seems to be asked by those who had to have it laboriously
                     * explained to them, and who can't even concisely describe
                     * the conditions under which one would be forced to resort to
                     * this technique.  Needless to say, those conditions are
                     * found here -- and probably only here.  Is this the only use
                     * of this infamous trick in shipping, production code?  If it
                     * isn't, it probably should be...
                     */
                    if (minor != -1) {
                              uintptr_t maddr = dtrace_loadptr(daddr +
                                  offsetof(struct dev_info, devi_minor));

                              uintptr_t next = offsetof(struct ddi_minor_data, next);
                              uintptr_t name = offsetof(struct ddi_minor_data,
                                  d_minor) + offsetof(struct ddi_minor, name);
                              uintptr_t dev = offsetof(struct ddi_minor_data,
                                  d_minor) + offsetof(struct ddi_minor, dev);
                              uintptr_t scout;

                              if (maddr != NULL)
                                        scout = dtrace_loadptr(maddr + next);

                              while (maddr != NULL && !(*flags & CPU_DTRACE_FAULT)) {
                                        uint64_t m;
#ifdef _LP64
                                        m = dtrace_load64(maddr + dev) & MAXMIN64;
#else
                                        m = dtrace_load32(maddr + dev) & MAXMIN;
#endif
                                        if (m != minor) {
                                                  maddr = dtrace_loadptr(maddr + next);

                                                  if (scout == NULL)
                                                            continue;

                                                  scout = dtrace_loadptr(scout + next);

                                                  if (scout == NULL)
                                                            continue;

                                                  scout = dtrace_loadptr(scout + next);

                                                  if (scout == NULL)
                                                            continue;

                                                  if (scout == maddr) {
                                                            *flags |= CPU_DTRACE_ILLOP;
                                                            break;
                                                  }

                                                  continue;
                                        }

                                        /*
                                         * We have the minor data.  Now we need to
                                         * copy the minor's name into the end of the
                                         * pathname.
                                         */
                                        s = (char *)dtrace_loadptr(maddr + name);
                                        len = dtrace_strlen(s, size);

                                        if (*flags & CPU_DTRACE_FAULT)
                                                  break;

                                        if (len != 0) {
                                                  if ((end -= (len + 1)) < start)
                                                            break;

                                                  *end = ':';
                                        }

                                        for (i = 1; i <= len; i++)
                                                  end[i] = dtrace_load8((uintptr_t)s++);
                                        break;
                              }
                    }

                    while (daddr != NULL && !(*flags & CPU_DTRACE_FAULT)) {
                              ddi_node_state_t devi_state;

                              devi_state = dtrace_load32(daddr +
                                  offsetof(struct dev_info, devi_node_state));

                              if (*flags & CPU_DTRACE_FAULT)
                                        break;

                              if (devi_state >= DS_INITIALIZED) {
                                        s = (char *)dtrace_loadptr(daddr +
                                            offsetof(struct dev_info, devi_addr));
                                        len = dtrace_strlen(s, size);

                                        if (*flags & CPU_DTRACE_FAULT)
                                                  break;

                                        if (len != 0) {
                                                  if ((end -= (len + 1)) < start)
                                                            break;

                                                  *end = '@';
                                        }

                                        for (i = 1; i <= len; i++)
                                                  end[i] = dtrace_load8((uintptr_t)s++);
                              }

                              /*
                               * Now for the node name...
                               */
                              s = (char *)dtrace_loadptr(daddr +
                                  offsetof(struct dev_info, devi_node_name));

                              daddr = dtrace_loadptr(daddr +
                                  offsetof(struct dev_info, devi_parent));

                              /*
                               * If our parent is NULL (that is, if we're the root
                               * node), we're going to use the special path
                               * "devices".
                               */
                              if (daddr == 0)
                                        s = "devices";

                              len = dtrace_strlen(s, size);
                              if (*flags & CPU_DTRACE_FAULT)
                                        break;

                              if ((end -= (len + 1)) < start)
                                        break;

                              for (i = 1; i <= len; i++)
                                        end[i] = dtrace_load8((uintptr_t)s++);
                              *end = '/';

                              if (depth++ > dtrace_devdepth_max) {
                                        *flags |= CPU_DTRACE_ILLOP;
                                        break;
                              }
                    }

                    if (end < start)
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);

                    if (daddr == 0) {
                              regs[rd] = (uintptr_t)end;
                              mstate->dtms_scratch_ptr += size;
                    }

                    break;
          }
#endif

          case DIF_SUBR_STRJOIN: {
                    char *d = (char *)mstate->dtms_scratch_ptr;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    uintptr_t s1 = tupregs[0].dttk_value;
                    uintptr_t s2 = tupregs[1].dttk_value;
                    int i = 0, j = 0;
                    size_t lim1, lim2;
                    char c;

                    if (!dtrace_strcanload(s1, size, &lim1, mstate, vstate) ||
                        !dtrace_strcanload(s2, size, &lim2, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    for (;;) {
                              if (i >= size) {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                        regs[rd] = 0;
                                        break;
                              }

                              c = (i >= lim1) ? '\0' : dtrace_load8(s1++);
                              if ((d[i++] = c) == '\0') {
                                        i--;
                                        break;
                              }
                    }

                    for (;;) {
                              if (i >= size) {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                        regs[rd] = 0;
                                        break;
                              }

                              c = (j++ >= lim2) ? '\0' : dtrace_load8(s2++);
                              if ((d[i++] = c) == '\0')
                                        break;
                    }

                    if (i < size) {
                              mstate->dtms_scratch_ptr += i;
                              regs[rd] = (uintptr_t)d;
                    }

                    break;
          }

          case DIF_SUBR_STRTOLL: {
                    uintptr_t s = tupregs[0].dttk_value;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    size_t lim;
                    int base = 10;

                    if (nargs > 1) {
                              if ((base = tupregs[1].dttk_value) <= 1 ||
                                  base > ('z' - 'a' + 1) + ('9' - '0' + 1)) {
                                        *flags |= CPU_DTRACE_ILLOP;
                                        break;
                              }
                    }

                    if (!dtrace_strcanload(s, size, &lim, mstate, vstate)) {
                              regs[rd] = INT64_MIN;
                              break;
                    }

                    regs[rd] = dtrace_strtoll((char *)s, base, lim);
                    break;
          }

          case DIF_SUBR_LLTOSTR: {
                    int64_t i = (int64_t)tupregs[0].dttk_value;
                    uint64_t val, digit;
                    uint64_t size = 65; /* enough room for 2^64 in binary */
                    char *end = (char *)mstate->dtms_scratch_ptr + size - 1;
                    int base = 10;

                    if (nargs > 1) {
                              if ((base = tupregs[1].dttk_value) <= 1 ||
                                  base > ('z' - 'a' + 1) + ('9' - '0' + 1)) {
                                        *flags |= CPU_DTRACE_ILLOP;
                                        break;
                              }
                    }

                    val = (base == 10 && i < 0) ? i * -1 : i;

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    for (*end-- = '\0'; val; val /= base) {
                              if ((digit = val % base) <= '9' - '0') {
                                        *end-- = '0' + digit;
                              } else {
                                        *end-- = 'a' + (digit - ('9' - '0') - 1);
                              }
                    }

                    if (i == 0 && base == 16)
                              *end-- = '0';

                    if (base == 16)
                              *end-- = 'x';

                    if (i == 0 || base == 8 || base == 16)
                              *end-- = '0';

                    if (i < 0 && base == 10)
                              *end-- = '-';

                    regs[rd] = (uintptr_t)end + 1;
                    mstate->dtms_scratch_ptr += size;
                    break;
          }

          case DIF_SUBR_HTONS:
          case DIF_SUBR_NTOHS:
#if BYTE_ORDER == BIG_ENDIAN
                    regs[rd] = (uint16_t)tupregs[0].dttk_value;
#else
                    regs[rd] = DT_BSWAP_16((uint16_t)tupregs[0].dttk_value);
#endif
                    break;


          case DIF_SUBR_HTONL:
          case DIF_SUBR_NTOHL:
#if BYTE_ORDER == BIG_ENDIAN
                    regs[rd] = (uint32_t)tupregs[0].dttk_value;
#else
                    regs[rd] = DT_BSWAP_32((uint32_t)tupregs[0].dttk_value);
#endif
                    break;


          case DIF_SUBR_HTONLL:
          case DIF_SUBR_NTOHLL:
#if BYTE_ORDER == BIG_ENDIAN
                    regs[rd] = (uint64_t)tupregs[0].dttk_value;
#else
                    regs[rd] = DT_BSWAP_64((uint64_t)tupregs[0].dttk_value);
#endif
                    break;


          case DIF_SUBR_DIRNAME:
          case DIF_SUBR_BASENAME: {
                    char *dest = (char *)mstate->dtms_scratch_ptr;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    uintptr_t src = tupregs[0].dttk_value;
                    int i, j, len = dtrace_strlen((char *)src, size);
                    int lastbase = -1, firstbase = -1, lastdir = -1;
                    int start, end;

                    if (!dtrace_canload(src, len + 1, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    /*
                     * The basename and dirname for a zero-length string is
                     * defined to be "."
                     */
                    if (len == 0) {
                              len = 1;
                              src = (uintptr_t)".";
                    }

                    /*
                     * Start from the back of the string, moving back toward the
                     * front until we see a character that isn't a slash.  That
                     * character is the last character in the basename.
                     */
                    for (i = len - 1; i >= 0; i--) {
                              if (dtrace_load8(src + i) != '/')
                                        break;
                    }

                    if (i >= 0)
                              lastbase = i;

                    /*
                     * Starting from the last character in the basename, move
                     * towards the front until we find a slash.  The character
                     * that we processed immediately before that is the first
                     * character in the basename.
                     */
                    for (; i >= 0; i--) {
                              if (dtrace_load8(src + i) == '/')
                                        break;
                    }

                    if (i >= 0)
                              firstbase = i + 1;

                    /*
                     * Now keep going until we find a non-slash character.  That
                     * character is the last character in the dirname.
                     */
                    for (; i >= 0; i--) {
                              if (dtrace_load8(src + i) != '/')
                                        break;
                    }

                    if (i >= 0)
                              lastdir = i;

                    ASSERT(!(lastbase == -1 && firstbase != -1));
                    ASSERT(!(firstbase == -1 && lastdir != -1));

                    if (lastbase == -1) {
                              /*
                               * We didn't find a non-slash character.  We know that
                               * the length is non-zero, so the whole string must be
                               * slashes.  In either the dirname or the basename
                               * case, we return '/'.
                               */
                              ASSERT(firstbase == -1);
                              firstbase = lastbase = lastdir = 0;
                    }

                    if (firstbase == -1) {
                              /*
                               * The entire string consists only of a basename
                               * component.  If we're looking for dirname, we need
                               * to change our string to be just "."; if we're
                               * looking for a basename, we'll just set the first
                               * character of the basename to be 0.
                               */
                              if (subr == DIF_SUBR_DIRNAME) {
                                        ASSERT(lastdir == -1);
                                        src = (uintptr_t)".";
                                        lastdir = 0;
                              } else {
                                        firstbase = 0;
                              }
                    }

                    if (subr == DIF_SUBR_DIRNAME) {
                              if (lastdir == -1) {
                                        /*
                                         * We know that we have a slash in the name --
                                         * or lastdir would be set to 0, above.  And
                                         * because lastdir is -1, we know that this
                                         * slash must be the first character.  (That
                                         * is, the full string must be of the form
                                         * "/basename".)  In this case, the last
                                         * character of the directory name is 0.
                                         */
                                        lastdir = 0;
                              }

                              start = 0;
                              end = lastdir;
                    } else {
                              ASSERT(subr == DIF_SUBR_BASENAME);
                              ASSERT(firstbase != -1 && lastbase != -1);
                              start = firstbase;
                              end = lastbase;
                    }

                    for (i = start, j = 0; i <= end && j < size - 1; i++, j++)
                              dest[j] = dtrace_load8(src + i);

                    dest[j] = '\0';
                    regs[rd] = (uintptr_t)dest;
                    mstate->dtms_scratch_ptr += size;
                    break;
          }

          case DIF_SUBR_GETF: {
                    uintptr_t fd = tupregs[0].dttk_value;
                    struct filedesc *fdp;
                    file_t *fp;

                    if (!dtrace_priv_proc(state)) {
                              regs[rd] = 0;
                              break;
                    }
#ifdef __FreeBSD_
                    fdp = curproc->p_fd;
                    FILEDESC_SLOCK(fdp);
                    fp = fget_locked(fdp, fd);
                    mstate->dtms_getf = fp;
                    regs[rd] = (uintptr_t)fp;
                    FILEDESC_SUNLOCK(fdp);
#endif
#ifdef __NetBSD__
                    regs[rd] = 0;
#endif
                    break;
          }
          case DIF_SUBR_CLEANPATH: {
                    char *dest = (char *)mstate->dtms_scratch_ptr, c;
                    uint64_t size = state->dts_options[DTRACEOPT_STRSIZE];
                    uintptr_t src = tupregs[0].dttk_value;
                    size_t lim;
                    int i = 0, j = 0;
#ifdef illumos
                    zone_t *z;
#endif

                    if (!dtrace_strcanload(src, size, &lim, mstate, vstate)) {
                              regs[rd] = 0;
                              break;
                    }

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              regs[rd] = 0;
                              break;
                    }

                    /*
                     * Move forward, loading each character.
                     */
                    do {
                              c = (i >= lim) ? '\0' : dtrace_load8(src + i++);
next:
                              if (j + 5 >= size)  /* 5 = strlen("/..c\0") */
                                        break;

                              if (c != '/') {
                                        dest[j++] = c;
                                        continue;
                              }

                              c = (i >= lim) ? '\0' : dtrace_load8(src + i++);

                              if (c == '/') {
                                        /*
                                         * We have two slashes -- we can just advance
                                         * to the next character.
                                         */
                                        goto next;
                              }

                              if (c != '.') {
                                        /*
                                         * This is not "." and it's not ".." -- we can
                                         * just store the "/" and this character and
                                         * drive on.
                                         */
                                        dest[j++] = '/';
                                        dest[j++] = c;
                                        continue;
                              }

                              c = (i >= lim) ? '\0' : dtrace_load8(src + i++);

                              if (c == '/') {
                                        /*
                                         * This is a "/./" component.  We're not going
                                         * to store anything in the destination buffer;
                                         * we're just going to go to the next component.
                                         */
                                        goto next;
                              }

                              if (c != '.') {
                                        /*
                                         * This is not ".." -- we can just store the
                                         * "/." and this character and continue
                                         * processing.
                                         */
                                        dest[j++] = '/';
                                        dest[j++] = '.';
                                        dest[j++] = c;
                                        continue;
                              }

                              c = (i >= lim) ? '\0' : dtrace_load8(src + i++);

                              if (c != '/' && c != '\0') {
                                        /*
                                         * This is not ".." -- it's "..[mumble]".
                                         * We'll store the "/.." and this character
                                         * and continue processing.
                                         */
                                        dest[j++] = '/';
                                        dest[j++] = '.';
                                        dest[j++] = '.';
                                        dest[j++] = c;
                                        continue;
                              }

                              /*
                               * This is "/../" or "/..\0".  We need to back up
                               * our destination pointer until we find a "/".
                               */
                              i--;
                              while (j != 0 && dest[--j] != '/')
                                        continue;

                              if (c == '\0')
                                        dest[++j] = '/';
                    } while (c != '\0');

                    dest[j] = '\0';

#ifdef illumos
                    if (mstate->dtms_getf != NULL &&
                        !(mstate->dtms_access & DTRACE_ACCESS_KERNEL) &&
                        (z = state->dts_cred.dcr_cred->cr_zone) != kcred->cr_zone) {
                              /*
                               * If we've done a getf() as a part of this ECB and we
                               * don't have kernel access (and we're not in the global
                               * zone), check if the path we cleaned up begins with
                               * the zone's root path, and trim it off if so.  Note
                               * that this is an output cleanliness issue, not a
                               * security issue: knowing one's zone root path does
                               * not enable privilege escalation.
                               */
                              if (strstr(dest, z->zone_rootpath) == dest)
                                        dest += strlen(z->zone_rootpath) - 1;
                    }
#endif

                    regs[rd] = (uintptr_t)dest;
                    mstate->dtms_scratch_ptr += size;
                    break;
          }

          case DIF_SUBR_INET_NTOA:
          case DIF_SUBR_INET_NTOA6:
          case DIF_SUBR_INET_NTOP: {
                    size_t size;
                    int af, argi, i;
                    char *base, *end;

                    if (subr == DIF_SUBR_INET_NTOP) {
                              af = (int)tupregs[0].dttk_value;
                              argi = 1;
                    } else {
                              af = subr == DIF_SUBR_INET_NTOA ? AF_INET: AF_INET6;
                              argi = 0;
                    }

                    if (af == AF_INET) {
                              ipaddr_t ip4;
                              uint8_t *ptr8, val;

                              if (!dtrace_canload(tupregs[argi].dttk_value,
                                  sizeof (ipaddr_t), mstate, vstate)) {
                                        regs[rd] = 0;
                                        break;
                              }

                              /*
                               * Safely load the IPv4 address.
                               */
                              ip4 = dtrace_load32(tupregs[argi].dttk_value);

                              /*
                               * Check an IPv4 string will fit in scratch.
                               */
                              size = INET_ADDRSTRLEN;
                              if (!DTRACE_INSCRATCH(mstate, size)) {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                        regs[rd] = 0;
                                        break;
                              }
                              base = (char *)mstate->dtms_scratch_ptr;
                              end = (char *)mstate->dtms_scratch_ptr + size - 1;

                              /*
                               * Stringify as a dotted decimal quad.
                               */
                              *end-- = '\0';
                              ptr8 = (uint8_t *)&ip4;
                              for (i = 3; i >= 0; i--) {
                                        val = ptr8[i];

                                        if (val == 0) {
                                                  *end-- = '0';
                                        } else {
                                                  for (; val; val /= 10) {
                                                            *end-- = '0' + (val % 10);
                                                  }
                                        }

                                        if (i > 0)
                                                  *end-- = '.';
                              }
                              ASSERT(end + 1 >= base);

                    } else if (af == AF_INET6) {
                              struct in6_addr ip6;
                              int firstzero, tryzero, numzero, v6end;
                              uint16_t val;
                              const char digits[] = "0123456789abcdef";

                              /*
                               * Stringify using RFC 1884 convention 2 - 16 bit
                               * hexadecimal values with a zero-run compression.
                               * Lower case hexadecimal digits are used.
                               *        eg, fe80::214:4fff:fe0b:76c8.
                               * The IPv4 embedded form is returned for inet_ntop,
                               * just the IPv4 string is returned for inet_ntoa6.
                               */

                              if (!dtrace_canload(tupregs[argi].dttk_value,
                                  sizeof (struct in6_addr), mstate, vstate)) {
                                        regs[rd] = 0;
                                        break;
                              }

                              /*
                               * Safely load the IPv6 address.
                               */
                              dtrace_bcopy(
                                  (void *)(uintptr_t)tupregs[argi].dttk_value,
                                  (void *)(uintptr_t)&ip6, sizeof (struct in6_addr));

                              /*
                               * Check an IPv6 string will fit in scratch.
                               */
                              size = INET6_ADDRSTRLEN;
                              if (!DTRACE_INSCRATCH(mstate, size)) {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                        regs[rd] = 0;
                                        break;
                              }
                              base = (char *)mstate->dtms_scratch_ptr;
                              end = (char *)mstate->dtms_scratch_ptr + size - 1;
                              *end-- = '\0';

                              /*
                               * Find the longest run of 16 bit zero values
                               * for the single allowed zero compression - "::".
                               */
                              firstzero = -1;
                              tryzero = -1;
                              numzero = 1;
                              for (i = 0; i < sizeof (struct in6_addr); i++) {
#ifdef illumos
                                        if (ip6._S6_un._S6_u8[i] == 0 &&
#else
                                        if (ip6.__u6_addr.__u6_addr8[i] == 0 &&
#endif
                                            tryzero == -1 && i % 2 == 0) {
                                                  tryzero = i;
                                                  continue;
                                        }

                                        if (tryzero != -1 &&
#ifdef illumos
                                            (ip6._S6_un._S6_u8[i] != 0 ||
#else
                                            (ip6.__u6_addr.__u6_addr8[i] != 0 ||
#endif
                                            i == sizeof (struct in6_addr) - 1)) {

                                                  if (i - tryzero <= numzero) {
                                                            tryzero = -1;
                                                            continue;
                                                  }

                                                  firstzero = tryzero;
                                                  numzero = i - i % 2 - tryzero;
                                                  tryzero = -1;

#ifdef illumos
                                                  if (ip6._S6_un._S6_u8[i] == 0 &&
#else
                                                  if (ip6.__u6_addr.__u6_addr8[i] == 0 &&
#endif
                                                      i == sizeof (struct in6_addr) - 1)
                                                            numzero += 2;
                                        }
                              }
                              ASSERT(firstzero + numzero <= sizeof (struct in6_addr));

                              /*
                               * Check for an IPv4 embedded address.
                               */
                              v6end = sizeof (struct in6_addr) - 2;
                              if (IN6_IS_ADDR_V4MAPPED(&ip6) ||
                                  IN6_IS_ADDR_V4COMPAT(&ip6)) {
                                        for (i = sizeof (struct in6_addr) - 1;
                                            i >= DTRACE_V4MAPPED_OFFSET; i--) {
                                                  ASSERT(end >= base);

#ifdef illumos
                                                  val = ip6._S6_un._S6_u8[i];
#else
                                                  val = ip6.__u6_addr.__u6_addr8[i];
#endif

                                                  if (val == 0) {
                                                            *end-- = '0';
                                                  } else {
                                                            for (; val; val /= 10) {
                                                                      *end-- = '0' + val % 10;
                                                            }
                                                  }

                                                  if (i > DTRACE_V4MAPPED_OFFSET)
                                                            *end-- = '.';
                                        }

                                        if (subr == DIF_SUBR_INET_NTOA6)
                                                  goto inetout;

                                        /*
                                         * Set v6end to skip the IPv4 address that
                                         * we have already stringified.
                                         */
                                        v6end = 10;
                              }

                              /*
                               * Build the IPv6 string by working through the
                               * address in reverse.
                               */
                              for (i = v6end; i >= 0; i -= 2) {
                                        ASSERT(end >= base);

                                        if (i == firstzero + numzero - 2) {
                                                  *end-- = ':';
                                                  *end-- = ':';
                                                  i -= numzero - 2;
                                                  continue;
                                        }

                                        if (i < 14 && i != firstzero - 2)
                                                  *end-- = ':';

#ifdef illumos
                                        val = (ip6._S6_un._S6_u8[i] << 8) +
                                            ip6._S6_un._S6_u8[i + 1];
#else
                                        val = (ip6.__u6_addr.__u6_addr8[i] << 8) +
                                            ip6.__u6_addr.__u6_addr8[i + 1];
#endif

                                        if (val == 0) {
                                                  *end-- = '0';
                                        } else {
                                                  for (; val; val /= 16) {
                                                            *end-- = digits[val % 16];
                                                  }
                                        }
                              }
                              ASSERT(end + 1 >= base);

                    } else {
                              /*
                               * The user didn't use AH_INET or AH_INET6.
                               */
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                              regs[rd] = 0;
                              break;
                    }

inetout:  regs[rd] = (uintptr_t)end + 1;
                    mstate->dtms_scratch_ptr += size;
                    break;
          }

          case DIF_SUBR_MEMREF: {
                    uintptr_t size = 2 * sizeof(uintptr_t);
                    uintptr_t *memref = (uintptr_t *) P2ROUNDUP(mstate->dtms_scratch_ptr, sizeof(uintptr_t));
                    size_t scratch_size = ((uintptr_t) memref - mstate->dtms_scratch_ptr) + size;

                    /* address and length */
                    memref[0] = tupregs[0].dttk_value;
                    memref[1] = tupregs[1].dttk_value;

                    regs[rd] = (uintptr_t) memref;
                    mstate->dtms_scratch_ptr += scratch_size;
                    break;
          }

#ifndef illumos
          case DIF_SUBR_MEMSTR: {
                    char *str = (char *)mstate->dtms_scratch_ptr;
                    uintptr_t mem = tupregs[0].dttk_value;
                    char c = tupregs[1].dttk_value;
                    size_t size = tupregs[2].dttk_value;
                    uint8_t n;
                    int i;

                    regs[rd] = 0;

                    if (size == 0)
                              break;

                    if (!dtrace_canload(mem, size - 1, mstate, vstate))
                              break;

                    if (!DTRACE_INSCRATCH(mstate, size)) {
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                              break;
                    }

                    if (dtrace_memstr_max != 0 && size > dtrace_memstr_max) {
                              *flags |= CPU_DTRACE_ILLOP;
                              break;
                    }

                    for (i = 0; i < size - 1; i++) {
                              n = dtrace_load8(mem++);
                              str[i] = (n == 0) ? c : n;
                    }
                    str[size - 1] = 0;

                    regs[rd] = (uintptr_t)str;
                    mstate->dtms_scratch_ptr += size;
                    break;
          }
#endif
          }
}

/*
 * Emulate the execution of DTrace IR instructions specified by the given
 * DIF object.  This function is deliberately void of assertions as all of
 * the necessary checks are handled by a call to dtrace_difo_validate().
 */
static uint64_t
dtrace_dif_emulate(dtrace_difo_t *difo, dtrace_mstate_t *mstate,
    dtrace_vstate_t *vstate, dtrace_state_t *state)
{
          const dif_instr_t *text = difo->dtdo_buf;
          const uint_t textlen = difo->dtdo_len;
          const char *strtab = difo->dtdo_strtab;
          const uint64_t *inttab = difo->dtdo_inttab;

          uint64_t rval = 0;
          dtrace_statvar_t *svar;
          dtrace_dstate_t *dstate = &vstate->dtvs_dynvars;
          dtrace_difv_t *v;
          volatile uint16_t *flags = &cpu_core[curcpu_id].cpuc_dtrace_flags;
          volatile uintptr_t *illval = &cpu_core[curcpu_id].cpuc_dtrace_illval;

          dtrace_key_t tupregs[DIF_DTR_NREGS + 2]; /* +2 for thread and id */
          uint64_t regs[DIF_DIR_NREGS];
          uint64_t *tmp;

          uint8_t cc_n = 0, cc_z = 0, cc_v = 0, cc_c = 0;
          int64_t cc_r;
          uint_t pc = 0, id, opc = 0;
          uint8_t ttop = 0;
          dif_instr_t instr;
          uint_t r1, r2, rd;

          /*
           * We stash the current DIF object into the machine state: we need it
           * for subsequent access checking.
           */
          mstate->dtms_difo = difo;

          regs[DIF_REG_R0] = 0;                   /* %r0 is fixed at zero */

          while (pc < textlen && !(*flags & CPU_DTRACE_FAULT)) {
                    opc = pc;

                    instr = text[pc++];
                    r1 = DIF_INSTR_R1(instr);
                    r2 = DIF_INSTR_R2(instr);
                    rd = DIF_INSTR_RD(instr);

                    switch (DIF_INSTR_OP(instr)) {
                    case DIF_OP_OR:
                              regs[rd] = regs[r1] | regs[r2];
                              break;
                    case DIF_OP_XOR:
                              regs[rd] = regs[r1] ^ regs[r2];
                              break;
                    case DIF_OP_AND:
                              regs[rd] = regs[r1] & regs[r2];
                              break;
                    case DIF_OP_SLL:
                              regs[rd] = regs[r1] << regs[r2];
                              break;
                    case DIF_OP_SRL:
                              regs[rd] = regs[r1] >> regs[r2];
                              break;
                    case DIF_OP_SUB:
                              regs[rd] = regs[r1] - regs[r2];
                              break;
                    case DIF_OP_ADD:
                              regs[rd] = regs[r1] + regs[r2];
                              break;
                    case DIF_OP_MUL:
                              regs[rd] = regs[r1] * regs[r2];
                              break;
                    case DIF_OP_SDIV:
                              if (regs[r2] == 0) {
                                        regs[rd] = 0;
                                        *flags |= CPU_DTRACE_DIVZERO;
                              } else {
                                        regs[rd] = (int64_t)regs[r1] /
                                            (int64_t)regs[r2];
                              }
                              break;

                    case DIF_OP_UDIV:
                              if (regs[r2] == 0) {
                                        regs[rd] = 0;
                                        *flags |= CPU_DTRACE_DIVZERO;
                              } else {
                                        regs[rd] = regs[r1] / regs[r2];
                              }
                              break;

                    case DIF_OP_SREM:
                              if (regs[r2] == 0) {
                                        regs[rd] = 0;
                                        *flags |= CPU_DTRACE_DIVZERO;
                              } else {
                                        regs[rd] = (int64_t)regs[r1] %
                                            (int64_t)regs[r2];
                              }
                              break;

                    case DIF_OP_UREM:
                              if (regs[r2] == 0) {
                                        regs[rd] = 0;
                                        *flags |= CPU_DTRACE_DIVZERO;
                              } else {
                                        regs[rd] = regs[r1] % regs[r2];
                              }
                              break;

                    case DIF_OP_NOT:
                              regs[rd] = ~regs[r1];
                              break;
                    case DIF_OP_MOV:
                              regs[rd] = regs[r1];
                              break;
                    case DIF_OP_CMP:
                              cc_r = regs[r1] - regs[r2];
                              cc_n = cc_r < 0;
                              cc_z = cc_r == 0;
                              cc_v = 0;
                              cc_c = regs[r1] < regs[r2];
                              break;
                    case DIF_OP_TST:
                              cc_n = cc_v = cc_c = 0;
                              cc_z = regs[r1] == 0;
                              break;
                    case DIF_OP_BA:
                              pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BE:
                              if (cc_z)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BNE:
                              if (cc_z == 0)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BG:
                              if ((cc_z | (cc_n ^ cc_v)) == 0)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BGU:
                              if ((cc_c | cc_z) == 0)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BGE:
                              if ((cc_n ^ cc_v) == 0)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BGEU:
                              if (cc_c == 0)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BL:
                              if (cc_n ^ cc_v)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BLU:
                              if (cc_c)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BLE:
                              if (cc_z | (cc_n ^ cc_v))
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_BLEU:
                              if (cc_c | cc_z)
                                        pc = DIF_INSTR_LABEL(instr);
                              break;
                    case DIF_OP_RLDSB:
                              if (!dtrace_canload(regs[r1], 1, mstate, vstate))
                                        break;
                              /*FALLTHROUGH*/
                    case DIF_OP_LDSB:
                              regs[rd] = (int8_t)dtrace_load8(regs[r1]);
                              break;
                    case DIF_OP_RLDSH:
                              if (!dtrace_canload(regs[r1], 2, mstate, vstate))
                                        break;
                              /*FALLTHROUGH*/
                    case DIF_OP_LDSH:
                              regs[rd] = (int16_t)dtrace_load16(regs[r1]);
                              break;
                    case DIF_OP_RLDSW:
                              if (!dtrace_canload(regs[r1], 4, mstate, vstate))
                                        break;
                              /*FALLTHROUGH*/
                    case DIF_OP_LDSW:
                              regs[rd] = (int32_t)dtrace_load32(regs[r1]);
                              break;
                    case DIF_OP_RLDUB:
                              if (!dtrace_canload(regs[r1], 1, mstate, vstate))
                                        break;
                              /*FALLTHROUGH*/
                    case DIF_OP_LDUB:
                              regs[rd] = dtrace_load8(regs[r1]);
                              break;
                    case DIF_OP_RLDUH:
                              if (!dtrace_canload(regs[r1], 2, mstate, vstate))
                                        break;
                              /*FALLTHROUGH*/
                    case DIF_OP_LDUH:
                              regs[rd] = dtrace_load16(regs[r1]);
                              break;
                    case DIF_OP_RLDUW:
                              if (!dtrace_canload(regs[r1], 4, mstate, vstate))
                                        break;
                              /*FALLTHROUGH*/
                    case DIF_OP_LDUW:
                              regs[rd] = dtrace_load32(regs[r1]);
                              break;
                    case DIF_OP_RLDX:
                              if (!dtrace_canload(regs[r1], 8, mstate, vstate))
                                        break;
                              /*FALLTHROUGH*/
                    case DIF_OP_LDX:
                              regs[rd] = dtrace_load64(regs[r1]);
                              break;
                    case DIF_OP_ULDSB:
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              regs[rd] = (int8_t)
                                  dtrace_fuword8((void *)(uintptr_t)regs[r1]);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              break;
                    case DIF_OP_ULDSH:
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              regs[rd] = (int16_t)
                                  dtrace_fuword16((void *)(uintptr_t)regs[r1]);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              break;
                    case DIF_OP_ULDSW:
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              regs[rd] = (int32_t)
                                  dtrace_fuword32((void *)(uintptr_t)regs[r1]);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              break;
                    case DIF_OP_ULDUB:
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              regs[rd] =
                                  dtrace_fuword8((void *)(uintptr_t)regs[r1]);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              break;
                    case DIF_OP_ULDUH:
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              regs[rd] =
                                  dtrace_fuword16((void *)(uintptr_t)regs[r1]);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              break;
                    case DIF_OP_ULDUW:
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              regs[rd] =
                                  dtrace_fuword32((void *)(uintptr_t)regs[r1]);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              break;
                    case DIF_OP_ULDX:
                              DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                              regs[rd] =
                                  dtrace_fuword64((void *)(uintptr_t)regs[r1]);
                              DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                              break;
                    case DIF_OP_RET:
                              rval = regs[rd];
                              pc = textlen;
                              break;
                    case DIF_OP_NOP:
                              break;
                    case DIF_OP_SETX:
                              regs[rd] = inttab[DIF_INSTR_INTEGER(instr)];
                              break;
                    case DIF_OP_SETS:
                              regs[rd] = (uint64_t)(uintptr_t)
                                  (strtab + DIF_INSTR_STRING(instr));
                              break;
                    case DIF_OP_SCMP: {
                              size_t sz = state->dts_options[DTRACEOPT_STRSIZE];
                              uintptr_t s1 = regs[r1];
                              uintptr_t s2 = regs[r2];
                              size_t lim1, lim2;

                              if (s1 != 0 &&
                                  !dtrace_strcanload(s1, sz, &lim1, mstate, vstate))
                                        break;
                              if (s2 != 0 &&
                                  !dtrace_strcanload(s2, sz, &lim2, mstate, vstate))
                                        break;

                              cc_r = dtrace_strncmp((char *)s1, (char *)s2,
                                  MIN(lim1, lim2));

                              cc_n = cc_r < 0;
                              cc_z = cc_r == 0;
                              cc_v = cc_c = 0;
                              break;
                    }
                    case DIF_OP_LDGA:
                              regs[rd] = dtrace_dif_variable(mstate, state,
                                  r1, regs[r2]);
                              break;
                    case DIF_OP_LDGS:
                              id = DIF_INSTR_VAR(instr);

                              if (id >= DIF_VAR_OTHER_UBASE) {
                                        uintptr_t a;

                                        id -= DIF_VAR_OTHER_UBASE;
                                        svar = vstate->dtvs_globals[id];
                                        ASSERT(svar != NULL);
                                        v = &svar->dtsv_var;

                                        if (!(v->dtdv_type.dtdt_flags & DIF_TF_BYREF)) {
                                                  regs[rd] = svar->dtsv_data;
                                                  break;
                                        }

                                        a = (uintptr_t)svar->dtsv_data;

                                        if (*(uint8_t *)a == UINT8_MAX) {
                                                  /*
                                                   * If the 0th byte is set to UINT8_MAX
                                                   * then this is to be treated as a
                                                   * reference to a NULL variable.
                                                   */
                                                  regs[rd] = 0;
                                        } else {
                                                  regs[rd] = a + sizeof (uint64_t);
                                        }

                                        break;
                              }

                              regs[rd] = dtrace_dif_variable(mstate, state, id, 0);
                              break;

                    case DIF_OP_STGS:
                              id = DIF_INSTR_VAR(instr);

                              ASSERT(id >= DIF_VAR_OTHER_UBASE);
                              id -= DIF_VAR_OTHER_UBASE;

                              VERIFY(id < vstate->dtvs_nglobals);
                              svar = vstate->dtvs_globals[id];
                              ASSERT(svar != NULL);
                              v = &svar->dtsv_var;

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                        uintptr_t a = (uintptr_t)svar->dtsv_data;
                                        size_t lim;

                                        ASSERT(a != 0);
                                        ASSERT(svar->dtsv_size != 0);

                                        if (regs[rd] == 0) {
                                                  *(uint8_t *)a = UINT8_MAX;
                                                  break;
                                        } else {
                                                  *(uint8_t *)a = 0;
                                                  a += sizeof (uint64_t);
                                        }
                                        if (!dtrace_vcanload(
                                            (void *)(uintptr_t)regs[rd], &v->dtdv_type,
                                            &lim, mstate, vstate))
                                                  break;

                                        dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                            (void *)a, &v->dtdv_type, lim);
                                        break;
                              }

                              svar->dtsv_data = regs[rd];
                              break;

                    case DIF_OP_LDTA:
                              /*
                               * There are no DTrace built-in thread-local arrays at
                               * present.  This opcode is saved for future work.
                               */
                              *flags |= CPU_DTRACE_ILLOP;
                              regs[rd] = 0;
                              break;

                    case DIF_OP_LDLS:
                              id = DIF_INSTR_VAR(instr);

                              if (id < DIF_VAR_OTHER_UBASE) {
                                        /*
                                         * For now, this has no meaning.
                                         */
                                        regs[rd] = 0;
                                        break;
                              }

                              id -= DIF_VAR_OTHER_UBASE;

                              ASSERT(id < vstate->dtvs_nlocals);
                              ASSERT(vstate->dtvs_locals != NULL);

                              svar = vstate->dtvs_locals[id];
                              ASSERT(svar != NULL);
                              v = &svar->dtsv_var;

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                        uintptr_t a = (uintptr_t)svar->dtsv_data;
                                        size_t sz = v->dtdv_type.dtdt_size;
                                        size_t lim;

                                        sz += sizeof (uint64_t);
                                        ASSERT(svar->dtsv_size == NCPU * sz);
                                        a += curcpu_id * sz;

                                        if (*(uint8_t *)a == UINT8_MAX) {
                                                  /*
                                                   * If the 0th byte is set to UINT8_MAX
                                                   * then this is to be treated as a
                                                   * reference to a NULL variable.
                                                   */
                                                  regs[rd] = 0;
                                        } else {
                                                  regs[rd] = a + sizeof (uint64_t);
                                        }

                                        break;
                              }

                              ASSERT(svar->dtsv_size == NCPU * sizeof (uint64_t));
                              tmp = (uint64_t *)(uintptr_t)svar->dtsv_data;
                              regs[rd] = tmp[curcpu_id];
                              break;

                    case DIF_OP_STLS:
                              id = DIF_INSTR_VAR(instr);

                              ASSERT(id >= DIF_VAR_OTHER_UBASE);
                              id -= DIF_VAR_OTHER_UBASE;
                              VERIFY(id < vstate->dtvs_nlocals);

                              ASSERT(vstate->dtvs_locals != NULL);
                              svar = vstate->dtvs_locals[id];
                              ASSERT(svar != NULL);
                              v = &svar->dtsv_var;

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                        uintptr_t a = (uintptr_t)svar->dtsv_data;
                                        size_t sz = v->dtdv_type.dtdt_size;
                                        size_t lim;

                                        sz += sizeof (uint64_t);
                                        ASSERT(svar->dtsv_size == NCPU * sz);
                                        a += curcpu_id * sz;

                                        if (regs[rd] == 0) {
                                                  *(uint8_t *)a = UINT8_MAX;
                                                  break;
                                        } else {
                                                  *(uint8_t *)a = 0;
                                                  a += sizeof (uint64_t);
                                        }

                                        if (!dtrace_vcanload(
                                            (void *)(uintptr_t)regs[rd], &v->dtdv_type,
                                            &lim, mstate, vstate))
                                                  break;

                                        dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                            (void *)a, &v->dtdv_type, lim);
                                        break;
                              }

                              ASSERT(svar->dtsv_size == NCPU * sizeof (uint64_t));
                              tmp = (uint64_t *)(uintptr_t)svar->dtsv_data;
                              tmp[curcpu_id] = regs[rd];
                              break;

                    case DIF_OP_LDTS: {
                              dtrace_dynvar_t *dvar;
                              dtrace_key_t *key;

                              id = DIF_INSTR_VAR(instr);
                              ASSERT(id >= DIF_VAR_OTHER_UBASE);
                              id -= DIF_VAR_OTHER_UBASE;
                              v = &vstate->dtvs_tlocals[id];

                              key = &tupregs[DIF_DTR_NREGS];
                              key[0].dttk_value = (uint64_t)id;
                              key[0].dttk_size = 0;
                              DTRACE_TLS_THRKEY(key[1].dttk_value);
                              key[1].dttk_size = 0;

                              dvar = dtrace_dynvar(dstate, 2, key,
                                  sizeof (uint64_t), DTRACE_DYNVAR_NOALLOC,
                                  mstate, vstate);

                              if (dvar == NULL) {
                                        regs[rd] = 0;
                                        break;
                              }

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                        regs[rd] = (uint64_t)(uintptr_t)dvar->dtdv_data;
                              } else {
                                        regs[rd] = *((uint64_t *)dvar->dtdv_data);
                              }

                              break;
                    }

                    case DIF_OP_STTS: {
                              dtrace_dynvar_t *dvar;
                              dtrace_key_t *key;

                              id = DIF_INSTR_VAR(instr);
                              ASSERT(id >= DIF_VAR_OTHER_UBASE);
                              id -= DIF_VAR_OTHER_UBASE;
                              VERIFY(id < vstate->dtvs_ntlocals);

                              key = &tupregs[DIF_DTR_NREGS];
                              key[0].dttk_value = (uint64_t)id;
                              key[0].dttk_size = 0;
                              DTRACE_TLS_THRKEY(key[1].dttk_value);
                              key[1].dttk_size = 0;
                              v = &vstate->dtvs_tlocals[id];

                              dvar = dtrace_dynvar(dstate, 2, key,
                                  v->dtdv_type.dtdt_size > sizeof (uint64_t) ?
                                  v->dtdv_type.dtdt_size : sizeof (uint64_t),
                                  regs[rd] ? DTRACE_DYNVAR_ALLOC :
                                  DTRACE_DYNVAR_DEALLOC, mstate, vstate);

                              /*
                               * Given that we're storing to thread-local data,
                               * we need to flush our predicate cache.
                               */
                              curthread->t_predcache = 0;

                              if (dvar == NULL)
                                        break;

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                        size_t lim;

                                        if (!dtrace_vcanload(
                                            (void *)(uintptr_t)regs[rd],
                                            &v->dtdv_type, &lim, mstate, vstate))
                                                  break;

                                        dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                            dvar->dtdv_data, &v->dtdv_type, lim);
                              } else {
                                        *((uint64_t *)dvar->dtdv_data) = regs[rd];
                              }

                              break;
                    }

                    case DIF_OP_SRA:
                              regs[rd] = (int64_t)regs[r1] >> regs[r2];
                              break;

                    case DIF_OP_CALL:
                              dtrace_dif_subr(DIF_INSTR_SUBR(instr), rd,
                                  regs, tupregs, ttop, mstate, state);
                              break;

                    case DIF_OP_PUSHTR:
                              if (ttop == DIF_DTR_NREGS) {
                                        *flags |= CPU_DTRACE_TUPOFLOW;
                                        break;
                              }

                              if (r1 == DIF_TYPE_STRING) {
                                        /*
                                         * If this is a string type and the size is 0,
                                         * we'll use the system-wide default string
                                         * size.  Note that we are _not_ looking at
                                         * the value of the DTRACEOPT_STRSIZE option;
                                         * had this been set, we would expect to have
                                         * a non-zero size value in the "pushtr".
                                         */
                                        tupregs[ttop].dttk_size =
                                            dtrace_strlen((char *)(uintptr_t)regs[rd],
                                            regs[r2] ? regs[r2] :
                                            dtrace_strsize_default) + 1;
                              } else {
                                        if (regs[r2] > LONG_MAX) {
                                                  *flags |= CPU_DTRACE_ILLOP;
                                                  break;
                                        }

                                        tupregs[ttop].dttk_size = regs[r2];
                              }

                              tupregs[ttop++].dttk_value = regs[rd];
                              break;

                    case DIF_OP_PUSHTV:
                              if (ttop == DIF_DTR_NREGS) {
                                        *flags |= CPU_DTRACE_TUPOFLOW;
                                        break;
                              }

                              tupregs[ttop].dttk_value = regs[rd];
                              tupregs[ttop++].dttk_size = 0;
                              break;

                    case DIF_OP_POPTS:
                              if (ttop != 0)
                                        ttop--;
                              break;

                    case DIF_OP_FLUSHTS:
                              ttop = 0;
                              break;

                    case DIF_OP_LDGAA:
                    case DIF_OP_LDTAA: {
                              dtrace_dynvar_t *dvar;
                              dtrace_key_t *key = tupregs;
                              uint_t nkeys = ttop;

                              id = DIF_INSTR_VAR(instr);
                              ASSERT(id >= DIF_VAR_OTHER_UBASE);
                              id -= DIF_VAR_OTHER_UBASE;

                              key[nkeys].dttk_value = (uint64_t)id;
                              key[nkeys++].dttk_size = 0;

                              if (DIF_INSTR_OP(instr) == DIF_OP_LDTAA) {
                                        DTRACE_TLS_THRKEY(key[nkeys].dttk_value);
                                        key[nkeys++].dttk_size = 0;
                                        VERIFY(id < vstate->dtvs_ntlocals);
                                        v = &vstate->dtvs_tlocals[id];
                              } else {
                                        VERIFY(id < vstate->dtvs_nglobals);
                                        v = &vstate->dtvs_globals[id]->dtsv_var;
                              }

                              dvar = dtrace_dynvar(dstate, nkeys, key,
                                  v->dtdv_type.dtdt_size > sizeof (uint64_t) ?
                                  v->dtdv_type.dtdt_size : sizeof (uint64_t),
                                  DTRACE_DYNVAR_NOALLOC, mstate, vstate);

                              if (dvar == NULL) {
                                        regs[rd] = 0;
                                        break;
                              }

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                        regs[rd] = (uint64_t)(uintptr_t)dvar->dtdv_data;
                              } else {
                                        regs[rd] = *((uint64_t *)dvar->dtdv_data);
                              }

                              break;
                    }

                    case DIF_OP_STGAA:
                    case DIF_OP_STTAA: {
                              dtrace_dynvar_t *dvar;
                              dtrace_key_t *key = tupregs;
                              uint_t nkeys = ttop;

                              id = DIF_INSTR_VAR(instr);
                              ASSERT(id >= DIF_VAR_OTHER_UBASE);
                              id -= DIF_VAR_OTHER_UBASE;

                              key[nkeys].dttk_value = (uint64_t)id;
                              key[nkeys++].dttk_size = 0;

                              if (DIF_INSTR_OP(instr) == DIF_OP_STTAA) {
                                        DTRACE_TLS_THRKEY(key[nkeys].dttk_value);
                                        key[nkeys++].dttk_size = 0;
                                        v = &vstate->dtvs_tlocals[id];
                              } else {
                                        v = &vstate->dtvs_globals[id]->dtsv_var;
                              }

                              dvar = dtrace_dynvar(dstate, nkeys, key,
                                  v->dtdv_type.dtdt_size > sizeof (uint64_t) ?
                                  v->dtdv_type.dtdt_size : sizeof (uint64_t),
                                  regs[rd] ? DTRACE_DYNVAR_ALLOC :
                                  DTRACE_DYNVAR_DEALLOC, mstate, vstate);

                              if (dvar == NULL)
                                        break;

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF) {
                                        size_t lim;

                                        if (!dtrace_vcanload(
                                            (void *)(uintptr_t)regs[rd], &v->dtdv_type,
                                            &lim, mstate, vstate))
                                                  break;

                                        dtrace_vcopy((void *)(uintptr_t)regs[rd],
                                            dvar->dtdv_data, &v->dtdv_type, lim);
                              } else {
                                        *((uint64_t *)dvar->dtdv_data) = regs[rd];
                              }

                              break;
                    }

                    case DIF_OP_ALLOCS: {
                              uintptr_t ptr = P2ROUNDUP(mstate->dtms_scratch_ptr, 8);
                              size_t size = ptr - mstate->dtms_scratch_ptr + regs[r1];

                              /*
                               * Rounding up the user allocation size could have
                               * overflowed large, bogus allocations (like -1ULL) to
                               * 0.
                               */
                              if (size < regs[r1] ||
                                  !DTRACE_INSCRATCH(mstate, size)) {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                                        regs[rd] = 0;
                                        break;
                              }

                              dtrace_bzero((void *) mstate->dtms_scratch_ptr, size);
                              mstate->dtms_scratch_ptr += size;
                              regs[rd] = ptr;
                              break;
                    }

                    case DIF_OP_COPYS:
                              if (!dtrace_canstore(regs[rd], regs[r2],
                                  mstate, vstate)) {
                                        *flags |= CPU_DTRACE_BADADDR;
                                        *illval = regs[rd];
                                        break;
                              }

                              if (!dtrace_canload(regs[r1], regs[r2], mstate, vstate))
                                        break;

                              dtrace_bcopy((void *)(uintptr_t)regs[r1],
                                  (void *)(uintptr_t)regs[rd], (size_t)regs[r2]);
                              break;

                    case DIF_OP_STB:
                              if (!dtrace_canstore(regs[rd], 1, mstate, vstate)) {
                                        *flags |= CPU_DTRACE_BADADDR;
                                        *illval = regs[rd];
                                        break;
                              }
                              *((uint8_t *)(uintptr_t)regs[rd]) = (uint8_t)regs[r1];
                              break;

                    case DIF_OP_STH:
                              if (!dtrace_canstore(regs[rd], 2, mstate, vstate)) {
                                        *flags |= CPU_DTRACE_BADADDR;
                                        *illval = regs[rd];
                                        break;
                              }
                              if (regs[rd] & 1) {
                                        *flags |= CPU_DTRACE_BADALIGN;
                                        *illval = regs[rd];
                                        break;
                              }
                              *((uint16_t *)(uintptr_t)regs[rd]) = (uint16_t)regs[r1];
                              break;

                    case DIF_OP_STW:
                              if (!dtrace_canstore(regs[rd], 4, mstate, vstate)) {
                                        *flags |= CPU_DTRACE_BADADDR;
                                        *illval = regs[rd];
                                        break;
                              }
                              if (regs[rd] & 3) {
                                        *flags |= CPU_DTRACE_BADALIGN;
                                        *illval = regs[rd];
                                        break;
                              }
                              *((uint32_t *)(uintptr_t)regs[rd]) = (uint32_t)regs[r1];
                              break;

                    case DIF_OP_STX:
                              if (!dtrace_canstore(regs[rd], 8, mstate, vstate)) {
                                        *flags |= CPU_DTRACE_BADADDR;
                                        *illval = regs[rd];
                                        break;
                              }
                              if (regs[rd] & 7) {
                                        *flags |= CPU_DTRACE_BADALIGN;
                                        *illval = regs[rd];
                                        break;
                              }
                              *((uint64_t *)(uintptr_t)regs[rd]) = regs[r1];
                              break;
                    }
          }

          if (!(*flags & CPU_DTRACE_FAULT))
                    return (rval);

          mstate->dtms_fltoffs = opc * sizeof (dif_instr_t);
          mstate->dtms_present |= DTRACE_MSTATE_FLTOFFS;

          return (0);
}

static void
dtrace_action_breakpoint(dtrace_ecb_t *ecb)
{
          dtrace_probe_t *probe = ecb->dte_probe;
          dtrace_provider_t *prov = probe->dtpr_provider;
          char c[DTRACE_FULLNAMELEN + 80], *str;
          const char *msg = "dtrace: breakpoint action at probe ";
          const char *ecbmsg = " (ecb ";
          uintptr_t mask = (0xf << (sizeof (uintptr_t) * NBBY / 4));
          uintptr_t val = (uintptr_t)ecb;
          int shift = (sizeof (uintptr_t) * NBBY) - 4, i = 0;

          if (dtrace_destructive_disallow)
                    return;

          /*
           * It's impossible to be taking action on the NULL probe.
           */
          ASSERT(probe != NULL);

          /*
           * This is a poor man's (destitute man's?) snprintf():  we want to
           * print the provider name, module name, function name and name of
           * the probe, along with the hex address of the ECB with the breakpoint
           * action -- all of which we must place in the character buffer by
           * hand.
           */
          while (*msg != '\0')
                    c[i++] = *msg++;

          for (str = prov->dtpv_name; *str != '\0'; str++)
                    c[i++] = *str;
          c[i++] = ':';

          for (str = probe->dtpr_mod; *str != '\0'; str++)
                    c[i++] = *str;
          c[i++] = ':';

          for (str = probe->dtpr_func; *str != '\0'; str++)
                    c[i++] = *str;
          c[i++] = ':';

          for (str = probe->dtpr_name; *str != '\0'; str++)
                    c[i++] = *str;

          while (*ecbmsg != '\0')
                    c[i++] = *ecbmsg++;

          while (shift >= 0) {
                    mask = (uintptr_t)0xf << shift;

                    if (val >= ((uintptr_t)1 << shift))
                              c[i++] = "0123456789abcdef"[(val & mask) >> shift];
                    shift -= 4;
          }

          c[i++] = ')';
          c[i] = '\0';

#ifdef illumos
          debug_enter(c);
#endif

#ifdef __FreeBSD__
          kdb_enter(KDB_WHY_DTRACE, "breakpoint action");
#endif

#ifdef __NetBSD__
#ifdef DDB
          db_printf("%s\n", c);
          Debugger();
#else
          printf("%s ignored\n", c);
#endif /* DDB */
#endif
}

static void
dtrace_action_panic(dtrace_ecb_t *ecb)
{
          dtrace_probe_t *probe = ecb->dte_probe;

          /*
           * It's impossible to be taking action on the NULL probe.
           */
          ASSERT(probe != NULL);

          if (dtrace_destructive_disallow)
                    return;

          if (dtrace_panicked != NULL)
                    return;

          if (dtrace_casptr(&dtrace_panicked, NULL, curthread) != NULL)
                    return;

          /*
           * We won the right to panic.  (We want to be sure that only one
           * thread calls panic() from dtrace_probe(), and that panic() is
           * called exactly once.)
           */
          dtrace_panic("dtrace: panic action at probe %s:%s:%s:%s (ecb %p)",
              probe->dtpr_provider->dtpv_name, probe->dtpr_mod,
              probe->dtpr_func, probe->dtpr_name, (void *)ecb);
}

static void
dtrace_action_raise(uint64_t sig)
{
          if (dtrace_destructive_disallow)
                    return;

          if (sig >= NSIG) {
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
                    return;
          }

#ifdef illumos
          /*
           * raise() has a queue depth of 1 -- we ignore all subsequent
           * invocations of the raise() action.
           */
          if (curthread->t_dtrace_sig == 0)
                    curthread->t_dtrace_sig = (uint8_t)sig;

          curthread->t_sig_check = 1;
          aston(curthread);
#endif

#ifdef __FreeBSD__
          PROC_LOCK(p);
          kern_psignal(p, sig);
          PROC_UNLOCK(p);
#endif

#ifdef __NetBSD__
          struct proc *p = curproc;
          mutex_enter(&proc_lock);
          psignal(p, sig);
          mutex_exit(&proc_lock);
#endif
}

static void
dtrace_action_stop(void)
{
          if (dtrace_destructive_disallow)
                    return;

#ifdef illumos
          if (!curthread->t_dtrace_stop) {
                    curthread->t_dtrace_stop = 1;
                    curthread->t_sig_check = 1;
                    aston(curthread);
          }
#endif

#ifdef __FreeBSD__
          PROC_LOCK(p);
          kern_psignal(p, SIGSTOP);
          PROC_UNLOCK(p);
#endif

#ifdef __NetBSD__
          struct proc *p = curproc;
          mutex_enter(&proc_lock);
          psignal(p, SIGSTOP);
          mutex_exit(&proc_lock);
#endif
}

static void
dtrace_action_chill(dtrace_mstate_t *mstate, hrtime_t val)
{
          hrtime_t now;
          volatile uint16_t *flags;
#ifdef illumos
          cpu_t *cpu = CPU;
#else
          cpu_t *cpu = &solaris_cpu[curcpu_id];
#endif

          if (dtrace_destructive_disallow)
                    return;

          flags = (volatile uint16_t *)&cpu_core[cpu->cpu_id].cpuc_dtrace_flags;

          now = dtrace_gethrtime();

          if (now - cpu->cpu_dtrace_chillmark > dtrace_chill_interval) {
                    /*
                     * We need to advance the mark to the current time.
                     */
                    cpu->cpu_dtrace_chillmark = now;
                    cpu->cpu_dtrace_chilled = 0;
          }

          /*
           * Now check to see if the requested chill time would take us over
           * the maximum amount of time allowed in the chill interval.  (Or
           * worse, if the calculation itself induces overflow.)
           */
          if (cpu->cpu_dtrace_chilled + val > dtrace_chill_max ||
              cpu->cpu_dtrace_chilled + val < cpu->cpu_dtrace_chilled) {
                    *flags |= CPU_DTRACE_ILLOP;
                    return;
          }

          while (dtrace_gethrtime() - now < val)
                    continue;

          /*
           * Normally, we assure that the value of the variable "timestamp" does
           * not change within an ECB.  The presence of chill() represents an
           * exception to this rule, however.
           */
          mstate->dtms_present &= ~DTRACE_MSTATE_TIMESTAMP;
          cpu->cpu_dtrace_chilled += val;
}

static void
dtrace_action_ustack(dtrace_mstate_t *mstate, dtrace_state_t *state,
    uint64_t *buf, uint64_t arg)
{
          int nframes = DTRACE_USTACK_NFRAMES(arg);
          int strsize = DTRACE_USTACK_STRSIZE(arg);
          uint64_t *pcs = &buf[1], *fps;
          char *str = (char *)&pcs[nframes];
          int size, offs = 0, i, j;
          size_t rem;
          uintptr_t old = mstate->dtms_scratch_ptr, saved;
          uint16_t *flags = &cpu_core[curcpu_id].cpuc_dtrace_flags;
          char *sym;

          /*
           * Should be taking a faster path if string space has not been
           * allocated.
           */
          ASSERT(strsize != 0);

          /*
           * We will first allocate some temporary space for the frame pointers.
           */
          fps = (uint64_t *)P2ROUNDUP(mstate->dtms_scratch_ptr, 8);
          size = (uintptr_t)fps - mstate->dtms_scratch_ptr +
              (nframes * sizeof (uint64_t));

          if (!DTRACE_INSCRATCH(mstate, size)) {
                    /*
                     * Not enough room for our frame pointers -- need to indicate
                     * that we ran out of scratch space.
                     */
                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOSCRATCH);
                    return;
          }

          mstate->dtms_scratch_ptr += size;
          saved = mstate->dtms_scratch_ptr;

          /*
           * Now get a stack with both program counters and frame pointers.
           */
          DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
          dtrace_getufpstack(buf, fps, nframes + 1);
          DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);

          /*
           * If that faulted, we're cooked.
           */
          if (*flags & CPU_DTRACE_FAULT)
                    goto out;

          /*
           * Now we want to walk up the stack, calling the USTACK helper.  For
           * each iteration, we restore the scratch pointer.
           */
          for (i = 0; i < nframes; i++) {
                    mstate->dtms_scratch_ptr = saved;

                    if (offs >= strsize)
                              break;

                    sym = (char *)(uintptr_t)dtrace_helper(
                        DTRACE_HELPER_ACTION_USTACK,
                        mstate, state, pcs[i], fps[i]);

                    /*
                     * If we faulted while running the helper, we're going to
                     * clear the fault and null out the corresponding string.
                     */
                    if (*flags & CPU_DTRACE_FAULT) {
                              *flags &= ~CPU_DTRACE_FAULT;
                              str[offs++] = '\0';
                              continue;
                    }

                    if (sym == NULL) {
                              str[offs++] = '\0';
                              continue;
                    }

                    if (!dtrace_strcanload((uintptr_t)sym, strsize, &rem, mstate,
                        &(state->dts_vstate))) {
                              str[offs++] = '\0';
                              continue;
                    }

                    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);

                    /*
                     * Now copy in the string that the helper returned to us.
                     */
                    for (j = 0; offs + j < strsize && j < rem; j++) {
                              if ((str[offs + j] = sym[j]) == '\0')
                                        break;
                    }

                    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);

                    offs += j + 1;
          }

          if (offs >= strsize) {
                    /*
                     * If we didn't have room for all of the strings, we don't
                     * abort processing -- this needn't be a fatal error -- but we
                     * still want to increment a counter (dts_stkstroverflows) to
                     * allow this condition to be warned about.  (If this is from
                     * a jstack() action, it is easily tuned via jstackstrsize.)
                     */
                    dtrace_error(&state->dts_stkstroverflows);
          }

          while (offs < strsize)
                    str[offs++] = '\0';

out:
          mstate->dtms_scratch_ptr = old;
}

static void
dtrace_store_by_ref(dtrace_difo_t *dp, caddr_t tomax, size_t size,
    size_t *valoffsp, uint64_t *valp, uint64_t end, int intuple, int dtkind)
{
          volatile uint16_t *flags;
          uint64_t val = *valp;
          size_t valoffs = *valoffsp;

          flags = (volatile uint16_t *)&cpu_core[curcpu_id].cpuc_dtrace_flags;
          ASSERT(dtkind == DIF_TF_BYREF || dtkind == DIF_TF_BYUREF);

          /*
           * If this is a string, we're going to only load until we find the zero
           * byte -- after which we'll store zero bytes.
           */
          if (dp->dtdo_rtype.dtdt_kind == DIF_TYPE_STRING) {
                    char c = '\0' + 1;
                    size_t s;

                    for (s = 0; s < size; s++) {
                              if (c != '\0' && dtkind == DIF_TF_BYREF) {
                                        c = dtrace_load8(val++);
                              } else if (c != '\0' && dtkind == DIF_TF_BYUREF) {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                        c = dtrace_fuword8((void *)(uintptr_t)val++);
                                        DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                                        if (*flags & CPU_DTRACE_FAULT)
                                                  break;
                              }

                              DTRACE_STORE(uint8_t, tomax, valoffs++, c);

                              if (c == '\0' && intuple)
                                        break;
                    }
          } else {
                    uint8_t c;
                    while (valoffs < end) {
                              if (dtkind == DIF_TF_BYREF) {
                                        c = dtrace_load8(val++);
                              } else if (dtkind == DIF_TF_BYUREF) {
                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                        c = dtrace_fuword8((void *)(uintptr_t)val++);
                                        DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                                        if (*flags & CPU_DTRACE_FAULT)
                                                  break;
                              }

                              DTRACE_STORE(uint8_t, tomax,
                                  valoffs++, c);
                    }
          }

          *valp = val;
          *valoffsp = valoffs;
}

/*
 * If you're looking for the epicenter of DTrace, you just found it.  This
 * is the function called by the provider to fire a probe -- from which all
 * subsequent probe-context DTrace activity emanates.
 */
void
dtrace_probe(dtrace_id_t id, uintptr_t arg0, uintptr_t arg1,
    uintptr_t arg2, uintptr_t arg3, uintptr_t arg4)
{
          processorid_t cpuid;
          dtrace_icookie_t cookie;
          dtrace_probe_t *probe;
          dtrace_mstate_t mstate;
          dtrace_ecb_t *ecb;
          dtrace_action_t *act;
          intptr_t offs;
          size_t size;
          int vtime, onintr;
          volatile uint16_t *flags;
          hrtime_t now;

          if (panicstr != NULL)
                    return;

#ifdef illumos
          /*
           * Kick out immediately if this CPU is still being born (in which case
           * curthread will be set to -1) or the current thread can't allow
           * probes in its current context.
           */
          if (((uintptr_t)curthread & 1) || (curthread->t_flag & T_DONTDTRACE))
                    return;
#endif

          cookie = dtrace_interrupt_disable();
          probe = dtrace_probes[id - 1];
          cpuid = curcpu_id;
          onintr = CPU_ON_INTR(CPU);

          if (!onintr && probe->dtpr_predcache != DTRACE_CACHEIDNONE &&
              probe->dtpr_predcache == curthread->t_predcache) {
                    /*
                     * We have hit in the predicate cache; we know that
                     * this predicate would evaluate to be false.
                     */
                    dtrace_interrupt_enable(cookie);
                    return;
          }

#ifdef illumos
          if (panic_quiesce) {
#else
          if (panicstr != NULL) {
#endif
                    /*
                     * We don't trace anything if we're panicking.
                     */
                    dtrace_interrupt_enable(cookie);
                    return;
          }

          now = mstate.dtms_timestamp = dtrace_gethrtime();
          mstate.dtms_present = DTRACE_MSTATE_TIMESTAMP;
          vtime = dtrace_vtime_references != 0;

          if (vtime && curthread->t_dtrace_start)
                    curthread->t_dtrace_vtime += now - curthread->t_dtrace_start;

          mstate.dtms_difo = NULL;
          mstate.dtms_probe = probe;
          mstate.dtms_strtok = 0;
          mstate.dtms_arg[0] = arg0;
          mstate.dtms_arg[1] = arg1;
          mstate.dtms_arg[2] = arg2;
          mstate.dtms_arg[3] = arg3;
          mstate.dtms_arg[4] = arg4;

          flags = (volatile uint16_t *)&cpu_core[cpuid].cpuc_dtrace_flags;

          for (ecb = probe->dtpr_ecb; ecb != NULL; ecb = ecb->dte_next) {
                    dtrace_predicate_t *pred = ecb->dte_predicate;
                    dtrace_state_t *state = ecb->dte_state;
                    dtrace_buffer_t *buf = &state->dts_buffer[cpuid];
                    dtrace_buffer_t *aggbuf = &state->dts_aggbuffer[cpuid];
                    dtrace_vstate_t *vstate = &state->dts_vstate;
                    dtrace_provider_t *prov = probe->dtpr_provider;
                    uint64_t tracememsize = 0;
                    int committed = 0;
                    caddr_t tomax;

                    /*
                     * A little subtlety with the following (seemingly innocuous)
                     * declaration of the automatic 'val':  by looking at the
                     * code, you might think that it could be declared in the
                     * action processing loop, below.  (That is, it's only used in
                     * the action processing loop.)  However, it must be declared
                     * out of that scope because in the case of DIF expression
                     * arguments to aggregating actions, one iteration of the
                     * action loop will use the last iteration's value.
                     */
                    uint64_t val = 0;

                    mstate.dtms_present = DTRACE_MSTATE_ARGS | DTRACE_MSTATE_PROBE;
                    mstate.dtms_getf = NULL;

                    *flags &= ~CPU_DTRACE_ERROR;

                    if (prov == dtrace_provider) {
                              /*
                               * If dtrace itself is the provider of this probe,
                               * we're only going to continue processing the ECB if
                               * arg0 (the dtrace_state_t) is equal to the ECB's
                               * creating state.  (This prevents disjoint consumers
                               * from seeing one another's metaprobes.)
                               */
                              if (arg0 != (uint64_t)(uintptr_t)state)
                                        continue;
                    }

                    if (state->dts_activity != DTRACE_ACTIVITY_ACTIVE) {
                              /*
                               * We're not currently active.  If our provider isn't
                               * the dtrace pseudo provider, we're not interested.
                               */
                              if (prov != dtrace_provider)
                                        continue;

                              /*
                               * Now we must further check if we are in the BEGIN
                               * probe.  If we are, we will only continue processing
                               * if we're still in WARMUP -- if one BEGIN enabling
                               * has invoked the exit() action, we don't want to
                               * evaluate subsequent BEGIN enablings.
                               */
                              if (probe->dtpr_id == dtrace_probeid_begin &&
                                  state->dts_activity != DTRACE_ACTIVITY_WARMUP) {
                                        ASSERT(state->dts_activity ==
                                            DTRACE_ACTIVITY_DRAINING);
                                        continue;
                              }
                    }

                    if (ecb->dte_cond) {
                              /*
                               * If the dte_cond bits indicate that this
                               * consumer is only allowed to see user-mode firings
                               * of this probe, call the provider's dtps_usermode()
                               * entry point to check that the probe was fired
                               * while in a user context. Skip this ECB if that's
                               * not the case.
                               */
                              if ((ecb->dte_cond & DTRACE_COND_USERMODE) &&
                                  prov->dtpv_pops.dtps_usermode(prov->dtpv_arg,
                                  probe->dtpr_id, probe->dtpr_arg) == 0)
                                        continue;

#ifdef illumos
                              /*
                               * This is more subtle than it looks. We have to be
                               * absolutely certain that CRED() isn't going to
                               * change out from under us so it's only legit to
                               * examine that structure if we're in constrained
                               * situations. Currently, the only times we'll this
                               * check is if a non-super-user has enabled the
                               * profile or syscall providers -- providers that
                               * allow visibility of all processes. For the
                               * profile case, the check above will ensure that
                               * we're examining a user context.
                               */
                              if (ecb->dte_cond & DTRACE_COND_OWNER) {
                                        cred_t *cr;
                                        cred_t *s_cr =
                                            ecb->dte_state->dts_cred.dcr_cred;
                                        proc_t *proc;

                                        ASSERT(s_cr != NULL);

                                        if ((cr = CRED()) == NULL ||
                                            s_cr->cr_uid != cr->cr_uid ||
                                            s_cr->cr_uid != cr->cr_ruid ||
                                            s_cr->cr_uid != cr->cr_suid ||
                                            s_cr->cr_gid != cr->cr_gid ||
                                            s_cr->cr_gid != cr->cr_rgid ||
                                            s_cr->cr_gid != cr->cr_sgid ||
                                            (proc = ttoproc(curthread)) == NULL ||
                                            (proc->p_flag & SNOCD))
                                                  continue;
                              }

                              if (ecb->dte_cond & DTRACE_COND_ZONEOWNER) {
                                        cred_t *cr;
                                        cred_t *s_cr =
                                            ecb->dte_state->dts_cred.dcr_cred;

                                        ASSERT(s_cr != NULL);

                                        if ((cr = CRED()) == NULL ||
                                            s_cr->cr_zone->zone_id !=
                                            cr->cr_zone->zone_id)
                                                  continue;
                              }
#endif
                    }

                    if (now - state->dts_alive > dtrace_deadman_timeout) {
                              /*
                               * We seem to be dead.  Unless we (a) have kernel
                               * destructive permissions (b) have explicitly enabled
                               * destructive actions and (c) destructive actions have
                               * not been disabled, we're going to transition into
                               * the KILLED state, from which no further processing
                               * on this state will be performed.
                               */
                              if (!dtrace_priv_kernel_destructive(state) ||
                                  !state->dts_cred.dcr_destructive ||
                                  dtrace_destructive_disallow) {
                                        void *activity = &state->dts_activity;
                                        dtrace_activity_t current;

                                        do {
                                                  current = state->dts_activity;
                                        } while (dtrace_cas32(activity, current,
                                            DTRACE_ACTIVITY_KILLED) != current);

                                        continue;
                              }
                    }

                    if ((offs = dtrace_buffer_reserve(buf, ecb->dte_needed,
                        ecb->dte_alignment, state, &mstate)) < 0)
                              continue;

                    tomax = buf->dtb_tomax;
                    ASSERT(tomax != NULL);

                    if (ecb->dte_size != 0) {
                              dtrace_rechdr_t dtrh;
                              if (!(mstate.dtms_present & DTRACE_MSTATE_TIMESTAMP)) {
                                        mstate.dtms_timestamp = dtrace_gethrtime();
                                        mstate.dtms_present |= DTRACE_MSTATE_TIMESTAMP;
                              }
                              ASSERT3U(ecb->dte_size, >=, sizeof (dtrace_rechdr_t));
                              dtrh.dtrh_epid = ecb->dte_epid;
                              DTRACE_RECORD_STORE_TIMESTAMP(&dtrh,
                                  mstate.dtms_timestamp);
                              *((dtrace_rechdr_t *)(tomax + offs)) = dtrh;
                    }

                    mstate.dtms_epid = ecb->dte_epid;
                    mstate.dtms_present |= DTRACE_MSTATE_EPID;

                    if (state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL)
                              mstate.dtms_access = DTRACE_ACCESS_KERNEL;
                    else
                              mstate.dtms_access = 0;

                    if (pred != NULL) {
                              dtrace_difo_t *dp = pred->dtp_difo;
                              uint64_t rval;

                              rval = dtrace_dif_emulate(dp, &mstate, vstate, state);

                              if (!(*flags & CPU_DTRACE_ERROR) && !rval) {
                                        dtrace_cacheid_t cid = probe->dtpr_predcache;

                                        if (cid != DTRACE_CACHEIDNONE && !onintr) {
                                                  /*
                                                   * Update the predicate cache...
                                                   */
                                                  ASSERT(cid == pred->dtp_cacheid);
                                                  curthread->t_predcache = cid;
                                        }

                                        continue;
                              }
                    }

                    for (act = ecb->dte_action; !(*flags & CPU_DTRACE_ERROR) &&
                        act != NULL; act = act->dta_next) {
                              size_t valoffs;
                              dtrace_difo_t *dp;
                              dtrace_recdesc_t *rec = &act->dta_rec;

                              size = rec->dtrd_size;
                              valoffs = offs + rec->dtrd_offset;

                              if (DTRACEACT_ISAGG(act->dta_kind)) {
                                        uint64_t v = 0xbad;
                                        dtrace_aggregation_t *agg;

                                        agg = (dtrace_aggregation_t *)act;

                                        if ((dp = act->dta_difo) != NULL)
                                                  v = dtrace_dif_emulate(dp,
                                                      &mstate, vstate, state);

                                        if (*flags & CPU_DTRACE_ERROR)
                                                  continue;

                                        /*
                                         * Note that we always pass the expression
                                         * value from the previous iteration of the
                                         * action loop.  This value will only be used
                                         * if there is an expression argument to the
                                         * aggregating action, denoted by the
                                         * dtag_hasarg field.
                                         */
                                        dtrace_aggregate(agg, buf,
                                            offs, aggbuf, v, val);
                                        continue;
                              }

                              switch (act->dta_kind) {
                              case DTRACEACT_STOP:
                                        if (dtrace_priv_proc_destructive(state))
                                                  dtrace_action_stop();
                                        continue;

                              case DTRACEACT_BREAKPOINT:
                                        if (dtrace_priv_kernel_destructive(state))
                                                  dtrace_action_breakpoint(ecb);
                                        continue;

                              case DTRACEACT_PANIC:
                                        if (dtrace_priv_kernel_destructive(state))
                                                  dtrace_action_panic(ecb);
                                        continue;

                              case DTRACEACT_STACK:
                                        if (!dtrace_priv_kernel(state))
                                                  continue;

                                        dtrace_getpcstack((pc_t *)(tomax + valoffs),
                                            size / sizeof (pc_t), probe->dtpr_aframes,
                                            DTRACE_ANCHORED(probe) ? NULL :
                                            (uint32_t *)arg0);
                                        continue;

                              case DTRACEACT_JSTACK:
                              case DTRACEACT_USTACK:
                                        if (!dtrace_priv_proc(state))
                                                  continue;

                                        /*
                                         * See comment in DIF_VAR_PID.
                                         */
                                        if (DTRACE_ANCHORED(mstate.dtms_probe) &&
                                            CPU_ON_INTR(CPU)) {
                                                  int depth = DTRACE_USTACK_NFRAMES(
                                                      rec->dtrd_arg) + 1;

                                                  dtrace_bzero((void *)(tomax + valoffs),
                                                      DTRACE_USTACK_STRSIZE(rec->dtrd_arg)
                                                      + depth * sizeof (uint64_t));

                                                  continue;
                                        }

                                        if (DTRACE_USTACK_STRSIZE(rec->dtrd_arg) != 0 &&
                                            curproc->p_dtrace_helpers != NULL) {
                                                  /*
                                                   * This is the slow path -- we have
                                                   * allocated string space, and we're
                                                   * getting the stack of a process that
                                                   * has helpers.  Call into a separate
                                                   * routine to perform this processing.
                                                   */
                                                  dtrace_action_ustack(&mstate, state,
                                                      (uint64_t *)(tomax + valoffs),
                                                      rec->dtrd_arg);
                                                  continue;
                                        }

                                        DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
                                        dtrace_getupcstack((uint64_t *)
                                            (tomax + valoffs),
                                            DTRACE_USTACK_NFRAMES(rec->dtrd_arg) + 1);
                                        DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);
                                        continue;

                              default:
                                        break;
                              }

                              dp = act->dta_difo;
                              ASSERT(dp != NULL);

                              val = dtrace_dif_emulate(dp, &mstate, vstate, state);

                              if (*flags & CPU_DTRACE_ERROR)
                                        continue;

                              switch (act->dta_kind) {
                              case DTRACEACT_SPECULATE: {
                                        dtrace_rechdr_t *dtrh;

                                        ASSERT(buf == &state->dts_buffer[cpuid]);
                                        buf = dtrace_speculation_buffer(state,
                                            cpuid, val);

                                        if (buf == NULL) {
                                                  *flags |= CPU_DTRACE_DROP;
                                                  continue;
                                        }

                                        offs = dtrace_buffer_reserve(buf,
                                            ecb->dte_needed, ecb->dte_alignment,
                                            state, NULL);

                                        if (offs < 0) {
                                                  *flags |= CPU_DTRACE_DROP;
                                                  continue;
                                        }

                                        tomax = buf->dtb_tomax;
                                        ASSERT(tomax != NULL);

                                        if (ecb->dte_size == 0)
                                                  continue;

                                        ASSERT3U(ecb->dte_size, >=,
                                            sizeof (dtrace_rechdr_t));
                                        dtrh = ((void *)(tomax + offs));
                                        dtrh->dtrh_epid = ecb->dte_epid;
                                        /*
                                         * When the speculation is committed, all of
                                         * the records in the speculative buffer will
                                         * have their timestamps set to the commit
                                         * time.  Until then, it is set to a sentinel
                                         * value, for debugability.
                                         */
                                        DTRACE_RECORD_STORE_TIMESTAMP(dtrh, UINT64_MAX);
                                        continue;
                              }

                              case DTRACEACT_PRINTM: {
                                        /* The DIF returns a 'memref'. */
                                        uintptr_t *memref = (uintptr_t *)(uintptr_t) val;

                                        /* Get the size from the memref. */
                                        size = memref[1];

                                        /*
                                         * Check if the size exceeds the allocated
                                         * buffer size.
                                         */
                                        if (size + sizeof(uintptr_t) > dp->dtdo_rtype.dtdt_size) {
                                                  /* Flag a drop! */
                                                  *flags |= CPU_DTRACE_DROP;
                                                  continue;
                                        }

                                        /* Store the size in the buffer first. */
                                        DTRACE_STORE(uintptr_t, tomax,
                                            valoffs, size);

                                        /*
                                         * Offset the buffer address to the start
                                         * of the data.
                                         */
                                        valoffs += sizeof(uintptr_t);

                                        /*
                                         * Reset to the memory address rather than
                                         * the memref array, then let the BYREF
                                         * code below do the work to store the
                                         * memory data in the buffer.
                                         */
                                        val = memref[0];
                                        break;
                              }

                              case DTRACEACT_CHILL:
                                        if (dtrace_priv_kernel_destructive(state))
                                                  dtrace_action_chill(&mstate, val);
                                        continue;

                              case DTRACEACT_RAISE:
                                        if (dtrace_priv_proc_destructive(state))
                                                  dtrace_action_raise(val);
                                        continue;

                              case DTRACEACT_COMMIT:
                                        ASSERT(!committed);

                                        /*
                                         * We need to commit our buffer state.
                                         */
                                        if (ecb->dte_size)
                                                  buf->dtb_offset = offs + ecb->dte_size;
                                        buf = &state->dts_buffer[cpuid];
                                        dtrace_speculation_commit(state, cpuid, val);
                                        committed = 1;
                                        continue;

                              case DTRACEACT_DISCARD:
                                        dtrace_speculation_discard(state, cpuid, val);
                                        continue;

                              case DTRACEACT_DIFEXPR:
                              case DTRACEACT_LIBACT:
                              case DTRACEACT_PRINTF:
                              case DTRACEACT_PRINTA:
                              case DTRACEACT_SYSTEM:
                              case DTRACEACT_FREOPEN:
                              case DTRACEACT_TRACEMEM:
                                        break;

                              case DTRACEACT_TRACEMEM_DYNSIZE:
                                        tracememsize = val;
                                        break;

                              case DTRACEACT_SYM:
                              case DTRACEACT_MOD:
                                        if (!dtrace_priv_kernel(state))
                                                  continue;
                                        break;

                              case DTRACEACT_USYM:
                              case DTRACEACT_UMOD:
                              case DTRACEACT_UADDR: {
#ifdef illumos
                                        struct pid *pid = curthread->t_procp->p_pidp;
#endif

                                        if (!dtrace_priv_proc(state))
                                                  continue;

                                        DTRACE_STORE(uint64_t, tomax,
#ifdef illumos
                                            valoffs, (uint64_t)pid->pid_id);
#else
                                            valoffs, (uint64_t) curproc->p_pid);
#endif
                                        DTRACE_STORE(uint64_t, tomax,
                                            valoffs + sizeof (uint64_t), val);

                                        continue;
                              }

                              case DTRACEACT_EXIT: {
                                        /*
                                         * For the exit action, we are going to attempt
                                         * to atomically set our activity to be
                                         * draining.  If this fails (either because
                                         * another CPU has beat us to the exit action,
                                         * or because our current activity is something
                                         * other than ACTIVE or WARMUP), we will
                                         * continue.  This assures that the exit action
                                         * can be successfully recorded at most once
                                         * when we're in the ACTIVE state.  If we're
                                         * encountering the exit() action while in
                                         * COOLDOWN, however, we want to honor the new
                                         * status code.  (We know that we're the only
                                         * thread in COOLDOWN, so there is no race.)
                                         */
                                        void *activity = &state->dts_activity;
                                        dtrace_activity_t current = state->dts_activity;

                                        if (current == DTRACE_ACTIVITY_COOLDOWN)
                                                  break;

                                        if (current != DTRACE_ACTIVITY_WARMUP)
                                                  current = DTRACE_ACTIVITY_ACTIVE;

                                        if (dtrace_cas32(activity, current,
                                            DTRACE_ACTIVITY_DRAINING) != current) {
                                                  *flags |= CPU_DTRACE_DROP;
                                                  continue;
                                        }

                                        break;
                              }

                              default:
                                        ASSERT(0);
                              }

                              if (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF ||
                                  dp->dtdo_rtype.dtdt_flags & DIF_TF_BYUREF) {
                                        uintptr_t end = valoffs + size;

                                        if (tracememsize != 0 &&
                                            valoffs + tracememsize < end) {
                                                  end = valoffs + tracememsize;
                                                  tracememsize = 0;
                                        }

                                        if (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF &&
                                            !dtrace_vcanload((void *)(uintptr_t)val,
                                            &dp->dtdo_rtype, NULL, &mstate, vstate))
                                                  continue;

                                        dtrace_store_by_ref(dp, tomax, size, &valoffs,
                                            &val, end, act->dta_intuple,
                                            dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF ?
                                            DIF_TF_BYREF: DIF_TF_BYUREF);
                                        continue;
                              }

                              switch (size) {
                              case 0:
                                        break;

                              case sizeof (uint8_t):
                                        DTRACE_STORE(uint8_t, tomax, valoffs, val);
                                        break;
                              case sizeof (uint16_t):
                                        DTRACE_STORE(uint16_t, tomax, valoffs, val);
                                        break;
                              case sizeof (uint32_t):
                                        DTRACE_STORE(uint32_t, tomax, valoffs, val);
                                        break;
                              case sizeof (uint64_t):
                                        DTRACE_STORE(uint64_t, tomax, valoffs, val);
                                        break;
                              default:
                                        /*
                                         * Any other size should have been returned by
                                         * reference, not by value.
                                         */
                                        ASSERT(0);
                                        break;
                              }
                    }

                    if (*flags & CPU_DTRACE_DROP)
                              continue;

                    if (*flags & CPU_DTRACE_FAULT) {
                              int ndx;
                              dtrace_action_t *err;

                              buf->dtb_errors++;

                              if (probe->dtpr_id == dtrace_probeid_error) {
                                        /*
                                         * There's nothing we can do -- we had an
                                         * error on the error probe.  We bump an
                                         * error counter to at least indicate that
                                         * this condition happened.
                                         */
                                        dtrace_error(&state->dts_dblerrors);
                                        continue;
                              }

                              if (vtime) {
                                        /*
                                         * Before recursing on dtrace_probe(), we
                                         * need to explicitly clear out our start
                                         * time to prevent it from being accumulated
                                         * into t_dtrace_vtime.
                                         */
                                        curthread->t_dtrace_start = 0;
                              }

                              /*
                               * Iterate over the actions to figure out which action
                               * we were processing when we experienced the error.
                               * Note that act points _past_ the faulting action; if
                               * act is ecb->dte_action, the fault was in the
                               * predicate, if it's ecb->dte_action->dta_next it's
                               * in action #1, and so on.
                               */
                              for (err = ecb->dte_action, ndx = 0;
                                  err != act; err = err->dta_next, ndx++)
                                        continue;

                              dtrace_probe_error(state, ecb->dte_epid, ndx,
                                  (mstate.dtms_present & DTRACE_MSTATE_FLTOFFS) ?
                                  mstate.dtms_fltoffs : -1, DTRACE_FLAGS2FLT(*flags),
                                  cpu_core[cpuid].cpuc_dtrace_illval);

                              continue;
                    }

                    if (!committed)
                              buf->dtb_offset = offs + ecb->dte_size;
          }

          if (vtime)
                    curthread->t_dtrace_start = dtrace_gethrtime();

          dtrace_interrupt_enable(cookie);
}

/*
 * DTrace Probe Hashing Functions
 *
 * The functions in this section (and indeed, the functions in remaining
 * sections) are not _called_ from probe context.  (Any exceptions to this are
 * marked with a "Note:".)  Rather, they are called from elsewhere in the
 * DTrace framework to look-up probes in, add probes to and remove probes from
 * the DTrace probe hashes.  (Each probe is hashed by each element of the
 * probe tuple -- allowing for fast lookups, regardless of what was
 * specified.)
 */
static uint_t
dtrace_hash_str(const char *p)
{
          unsigned int g;
          uint_t hval = 0;

          while (*p) {
                    hval = (hval << 4) + *p++;
                    if ((g = (hval & 0xf0000000)) != 0)
                              hval ^= g >> 24;
                    hval &= ~g;
          }
          return (hval);
}

static dtrace_hash_t *
dtrace_hash_create(uintptr_t stroffs, uintptr_t nextoffs, uintptr_t prevoffs)
{
          dtrace_hash_t *hash = kmem_zalloc(sizeof (dtrace_hash_t), KM_SLEEP);

          hash->dth_stroffs = stroffs;
          hash->dth_nextoffs = nextoffs;
          hash->dth_prevoffs = prevoffs;

          hash->dth_size = 1;
          hash->dth_mask = hash->dth_size - 1;

          hash->dth_tab = kmem_zalloc(hash->dth_size *
              sizeof (dtrace_hashbucket_t *), KM_SLEEP);

          return (hash);
}

static void
dtrace_hash_destroy(dtrace_hash_t *hash)
{
#ifdef DEBUG
          int i;

          for (i = 0; i < hash->dth_size; i++)
                    ASSERT(hash->dth_tab[i] == NULL);
#endif

          kmem_free(hash->dth_tab,
              hash->dth_size * sizeof (dtrace_hashbucket_t *));
          kmem_free(hash, sizeof (dtrace_hash_t));
}

static void
dtrace_hash_resize(dtrace_hash_t *hash)
{
          int size = hash->dth_size, i, ndx;
          int new_size = hash->dth_size << 1;
          int new_mask = new_size - 1;
          dtrace_hashbucket_t **new_tab, *bucket, *next;

          ASSERT((new_size & new_mask) == 0);

          new_tab = kmem_zalloc(new_size * sizeof (void *), KM_SLEEP);

          for (i = 0; i < size; i++) {
                    for (bucket = hash->dth_tab[i]; bucket != NULL; bucket = next) {
                              dtrace_probe_t *probe = bucket->dthb_chain;

                              ASSERT(probe != NULL);
                              ndx = DTRACE_HASHSTR(hash, probe) & new_mask;

                              next = bucket->dthb_next;
                              bucket->dthb_next = new_tab[ndx];
                              new_tab[ndx] = bucket;
                    }
          }

          kmem_free(hash->dth_tab, hash->dth_size * sizeof (void *));
          hash->dth_tab = new_tab;
          hash->dth_size = new_size;
          hash->dth_mask = new_mask;
}

static void
dtrace_hash_add(dtrace_hash_t *hash, dtrace_probe_t *new)
{
          int hashval = DTRACE_HASHSTR(hash, new);
          int ndx = hashval & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];
          dtrace_probe_t **nextp, **prevp;

          for (; bucket != NULL; bucket = bucket->dthb_next) {
                    if (DTRACE_HASHEQ(hash, bucket->dthb_chain, new))
                              goto add;
          }

          if ((hash->dth_nbuckets >> 1) > hash->dth_size) {
                    dtrace_hash_resize(hash);
                    dtrace_hash_add(hash, new);
                    return;
          }

          bucket = kmem_zalloc(sizeof (dtrace_hashbucket_t), KM_SLEEP);
          bucket->dthb_next = hash->dth_tab[ndx];
          hash->dth_tab[ndx] = bucket;
          hash->dth_nbuckets++;

add:
          nextp = DTRACE_HASHNEXT(hash, new);
          ASSERT(*nextp == NULL && *(DTRACE_HASHPREV(hash, new)) == NULL);
          *nextp = bucket->dthb_chain;

          if (bucket->dthb_chain != NULL) {
                    prevp = DTRACE_HASHPREV(hash, bucket->dthb_chain);
                    ASSERT(*prevp == NULL);
                    *prevp = new;
          }

          bucket->dthb_chain = new;
          bucket->dthb_len++;
}

static dtrace_probe_t *
dtrace_hash_lookup(dtrace_hash_t *hash, dtrace_probe_t *template)
{
          int hashval = DTRACE_HASHSTR(hash, template);
          int ndx = hashval & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];

          for (; bucket != NULL; bucket = bucket->dthb_next) {
                    if (DTRACE_HASHEQ(hash, bucket->dthb_chain, template))
                              return (bucket->dthb_chain);
          }

          return (NULL);
}

static int
dtrace_hash_collisions(dtrace_hash_t *hash, dtrace_probe_t *template)
{
          int hashval = DTRACE_HASHSTR(hash, template);
          int ndx = hashval & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];

          for (; bucket != NULL; bucket = bucket->dthb_next) {
                    if (DTRACE_HASHEQ(hash, bucket->dthb_chain, template))
                              return (bucket->dthb_len);
          }

          return (0);
}

static void
dtrace_hash_remove(dtrace_hash_t *hash, dtrace_probe_t *probe)
{
          int ndx = DTRACE_HASHSTR(hash, probe) & hash->dth_mask;
          dtrace_hashbucket_t *bucket = hash->dth_tab[ndx];

          dtrace_probe_t **prevp = DTRACE_HASHPREV(hash, probe);
          dtrace_probe_t **nextp = DTRACE_HASHNEXT(hash, probe);

          /*
           * Find the bucket that we're removing this probe from.
           */
          for (; bucket != NULL; bucket = bucket->dthb_next) {
                    if (DTRACE_HASHEQ(hash, bucket->dthb_chain, probe))
                              break;
          }

          ASSERT(bucket != NULL);

          if (*prevp == NULL) {
                    if (*nextp == NULL) {
                              /*
                               * The removed probe was the only probe on this
                               * bucket; we need to remove the bucket.
                               */
                              dtrace_hashbucket_t *b = hash->dth_tab[ndx];

                              ASSERT(bucket->dthb_chain == probe);
                              ASSERT(b != NULL);

                              if (b == bucket) {
                                        hash->dth_tab[ndx] = bucket->dthb_next;
                              } else {
                                        while (b->dthb_next != bucket)
                                                  b = b->dthb_next;
                                        b->dthb_next = bucket->dthb_next;
                              }

                              ASSERT(hash->dth_nbuckets > 0);
                              hash->dth_nbuckets--;
                              kmem_free(bucket, sizeof (dtrace_hashbucket_t));
                              return;
                    }

                    bucket->dthb_chain = *nextp;
          } else {
                    *(DTRACE_HASHNEXT(hash, *prevp)) = *nextp;
          }

          if (*nextp != NULL)
                    *(DTRACE_HASHPREV(hash, *nextp)) = *prevp;
}

/*
 * DTrace Utility Functions
 *
 * These are random utility functions that are _not_ called from probe context.
 */
static int
dtrace_badattr(const dtrace_attribute_t *a)
{
          return (a->dtat_name > DTRACE_STABILITY_MAX ||
              a->dtat_data > DTRACE_STABILITY_MAX ||
              a->dtat_class > DTRACE_CLASS_MAX);
}

/*
 * Return a duplicate copy of a string.  If the specified string is NULL,
 * this function returns a zero-length string.
 */
static char *
dtrace_strdup(const char *str)
{
          char *new = kmem_zalloc((str != NULL ? strlen(str) : 0) + 1, KM_SLEEP);

          if (str != NULL)
                    (void) strcpy(new, str);

          return (new);
}

#define   DTRACE_ISALPHA(c)   \
          (((c) >= 'a' && (c) <= 'z') || ((c) >= 'A' && (c) <= 'Z'))

static int
dtrace_badname(const char *s)
{
          char c;

          if (s == NULL || (c = *s++) == '\0')
                    return (0);

          if (!DTRACE_ISALPHA(c) && c != '-' && c != '_' && c != '.')
                    return (1);

          while ((c = *s++) != '\0') {
                    if (!DTRACE_ISALPHA(c) && (c < '0' || c > '9') &&
                        c != '-' && c != '_' && c != '.' && c != '`')
                              return (1);
          }

          return (0);
}

static void
dtrace_cred2priv(cred_t *cr, uint32_t *privp, uid_t *uidp, zoneid_t *zoneidp)
{
          uint32_t priv;

#ifdef illumos
          if (cr == NULL || PRIV_POLICY_ONLY(cr, PRIV_ALL, B_FALSE)) {
                    /*
                     * For DTRACE_PRIV_ALL, the uid and zoneid don't matter.
                     */
                    priv = DTRACE_PRIV_ALL;
          } else {
                    *uidp = crgetuid(cr);
                    *zoneidp = crgetzoneid(cr);

                    priv = 0;
                    if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_KERNEL, B_FALSE))
                              priv |= DTRACE_PRIV_KERNEL | DTRACE_PRIV_USER;
                    else if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_USER, B_FALSE))
                              priv |= DTRACE_PRIV_USER;
                    if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_PROC, B_FALSE))
                              priv |= DTRACE_PRIV_PROC;
                    if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE))
                              priv |= DTRACE_PRIV_OWNER;
                    if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE))
                              priv |= DTRACE_PRIV_ZONEOWNER;
          }
#else
          priv = DTRACE_PRIV_ALL;
          *uidp = 0;
          *zoneidp = 0;
#endif

          *privp = priv;
}

#ifdef DTRACE_ERRDEBUG
static void
dtrace_errdebug(const char *str)
{
          int hval = dtrace_hash_str(str) % DTRACE_ERRHASHSZ;
          int occupied = 0;

          mutex_enter(&dtrace_errlock);
          dtrace_errlast = str;
          dtrace_errthread = curthread;

          while (occupied++ < DTRACE_ERRHASHSZ) {
                    if (dtrace_errhash[hval].dter_msg == str) {
                              dtrace_errhash[hval].dter_count++;
                              goto out;
                    }

                    if (dtrace_errhash[hval].dter_msg != NULL) {
                              hval = (hval + 1) % DTRACE_ERRHASHSZ;
                              continue;
                    }

                    dtrace_errhash[hval].dter_msg = str;
                    dtrace_errhash[hval].dter_count = 1;
                    goto out;
          }

          panic("dtrace: undersized error hash");
out:
          mutex_exit(&dtrace_errlock);
}
#endif

/*
 * DTrace Matching Functions
 *
 * These functions are used to match groups of probes, given some elements of
 * a probe tuple, or some globbed expressions for elements of a probe tuple.
 */
static int
dtrace_match_priv(const dtrace_probe_t *prp, uint32_t priv, uid_t uid,
    zoneid_t zoneid)
{
          if (priv != DTRACE_PRIV_ALL) {
                    uint32_t ppriv = prp->dtpr_provider->dtpv_priv.dtpp_flags;
                    uint32_t match = priv & ppriv;

                    /*
                     * No PRIV_DTRACE_* privileges...
                     */
                    if ((priv & (DTRACE_PRIV_PROC | DTRACE_PRIV_USER |
                        DTRACE_PRIV_KERNEL)) == 0)
                              return (0);

                    /*
                     * No matching bits, but there were bits to match...
                     */
                    if (match == 0 && ppriv != 0)
                              return (0);

                    /*
                     * Need to have permissions to the process, but don't...
                     */
                    if (((ppriv & ~match) & DTRACE_PRIV_OWNER) != 0 &&
                        uid != prp->dtpr_provider->dtpv_priv.dtpp_uid) {
                              return (0);
                    }

                    /*
                     * Need to be in the same zone unless we possess the
                     * privilege to examine all zones.
                     */
                    if (((ppriv & ~match) & DTRACE_PRIV_ZONEOWNER) != 0 &&
                        zoneid != prp->dtpr_provider->dtpv_priv.dtpp_zoneid) {
                              return (0);
                    }
          }

          return (1);
}

/*
 * dtrace_match_probe compares a dtrace_probe_t to a pre-compiled key, which
 * consists of input pattern strings and an ops-vector to evaluate them.
 * This function returns >0 for match, 0 for no match, and <0 for error.
 */
static int
dtrace_match_probe(const dtrace_probe_t *prp, const dtrace_probekey_t *pkp,
    uint32_t priv, uid_t uid, zoneid_t zoneid)
{
          dtrace_provider_t *pvp = prp->dtpr_provider;
          int rv;

          if (pvp->dtpv_defunct)
                    return (0);

          if ((rv = pkp->dtpk_pmatch(pvp->dtpv_name, pkp->dtpk_prov, 0)) <= 0)
                    return (rv);

          if ((rv = pkp->dtpk_mmatch(prp->dtpr_mod, pkp->dtpk_mod, 0)) <= 0)
                    return (rv);

          if ((rv = pkp->dtpk_fmatch(prp->dtpr_func, pkp->dtpk_func, 0)) <= 0)
                    return (rv);

          if ((rv = pkp->dtpk_nmatch(prp->dtpr_name, pkp->dtpk_name, 0)) <= 0)
                    return (rv);

          if (dtrace_match_priv(prp, priv, uid, zoneid) == 0)
                    return (0);

          return (rv);
}

/*
 * dtrace_match_glob() is a safe kernel implementation of the gmatch(3GEN)
 * interface for matching a glob pattern 'p' to an input string 's'.  Unlike
 * libc's version, the kernel version only applies to 8-bit ASCII strings.
 * In addition, all of the recursion cases except for '*' matching have been
 * unwound.  For '*', we still implement recursive evaluation, but a depth
 * counter is maintained and matching is aborted if we recurse too deep.
 * The function returns 0 if no match, >0 if match, and <0 if recursion error.
 */
static int
dtrace_match_glob(const char *s, const char *p, int depth)
{
          const char *olds;
          char s1, c;
          int gs;

          if (depth > DTRACE_PROBEKEY_MAXDEPTH)
                    return (-1);

          if (s == NULL)
                    s = ""; /* treat NULL as empty string */

top:
          olds = s;
          s1 = *s++;

          if (p == NULL)
                    return (0);

          if ((c = *p++) == '\0')
                    return (s1 == '\0');

          switch (c) {
          case '[': {
                    int ok = 0, notflag = 0;
                    char lc = '\0';

                    if (s1 == '\0')
                              return (0);

                    if (*p == '!') {
                              notflag = 1;
                              p++;
                    }

                    if ((c = *p++) == '\0')
                              return (0);

                    do {
                              if (c == '-' && lc != '\0' && *p != ']') {
                                        if ((c = *p++) == '\0')
                                                  return (0);
                                        if (c == '\\' && (c = *p++) == '\0')
                                                  return (0);

                                        if (notflag) {
                                                  if (s1 < lc || s1 > c)
                                                            ok++;
                                                  else
                                                            return (0);
                                        } else if (lc <= s1 && s1 <= c)
                                                  ok++;

                              } else if (c == '\\' && (c = *p++) == '\0')
                                        return (0);

                              lc = c; /* save left-hand 'c' for next iteration */

                              if (notflag) {
                                        if (s1 != c)
                                                  ok++;
                                        else
                                                  return (0);
                              } else if (s1 == c)
                                        ok++;

                              if ((c = *p++) == '\0')
                                        return (0);

                    } while (c != ']');

                    if (ok)
                              goto top;

                    return (0);
          }

          case '\\':
                    if ((c = *p++) == '\0')
                              return (0);
                    /*FALLTHRU*/

          default:
                    if (c != s1)
                              return (0);
                    /*FALLTHRU*/

          case '?':
                    if (s1 != '\0')
                              goto top;
                    return (0);

          case '*':
                    while (*p == '*')
                              p++; /* consecutive *'s are identical to a single one */

                    if (*p == '\0')
                              return (1);

                    for (s = olds; *s != '\0'; s++) {
                              if ((gs = dtrace_match_glob(s, p, depth + 1)) != 0)
                                        return (gs);
                    }

                    return (0);
          }
}

/*ARGSUSED*/
static int
dtrace_match_string(const char *s, const char *p, int depth)
{
          return (s != NULL && strcmp(s, p) == 0);
}

/*ARGSUSED*/
static int
dtrace_match_nul(const char *s, const char *p, int depth)
{
          return (1); /* always match the empty pattern */
}

/*ARGSUSED*/
static int
dtrace_match_nonzero(const char *s, const char *p, int depth)
{
          return (s != NULL && s[0] != '\0');
}

static int
dtrace_match(const dtrace_probekey_t *pkp, uint32_t priv, uid_t uid,
    zoneid_t zoneid, int (*matched)(dtrace_probe_t *, void *), void *arg)
{
          dtrace_probe_t template, *probe;
          dtrace_hash_t *hash = NULL;
          int len, rc, best = INT_MAX, nmatched = 0;
          dtrace_id_t i;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          /*
           * If the probe ID is specified in the key, just lookup by ID and
           * invoke the match callback once if a matching probe is found.
           */
          if (pkp->dtpk_id != DTRACE_IDNONE) {
                    if ((probe = dtrace_probe_lookup_id(pkp->dtpk_id)) != NULL &&
                        dtrace_match_probe(probe, pkp, priv, uid, zoneid) > 0) {
                              if ((*matched)(probe, arg) == DTRACE_MATCH_FAIL)
                                        return (DTRACE_MATCH_FAIL);
                              nmatched++;
                    }
                    return (nmatched);
          }

          template.dtpr_mod = (char *)pkp->dtpk_mod;
          template.dtpr_func = (char *)pkp->dtpk_func;
          template.dtpr_name = (char *)pkp->dtpk_name;

          /*
           * We want to find the most distinct of the module name, function
           * name, and name.  So for each one that is not a glob pattern or
           * empty string, we perform a lookup in the corresponding hash and
           * use the hash table with the fewest collisions to do our search.
           */
          if (pkp->dtpk_mmatch == &dtrace_match_string &&
              (len = dtrace_hash_collisions(dtrace_bymod, &template)) < best) {
                    best = len;
                    hash = dtrace_bymod;
          }

          if (pkp->dtpk_fmatch == &dtrace_match_string &&
              (len = dtrace_hash_collisions(dtrace_byfunc, &template)) < best) {
                    best = len;
                    hash = dtrace_byfunc;
          }

          if (pkp->dtpk_nmatch == &dtrace_match_string &&
              (len = dtrace_hash_collisions(dtrace_byname, &template)) < best) {
                    best = len;
                    hash = dtrace_byname;
          }

          /*
           * If we did not select a hash table, iterate over every probe and
           * invoke our callback for each one that matches our input probe key.
           */
          if (hash == NULL) {
                    for (i = 0; i < dtrace_nprobes; i++) {
                              if ((probe = dtrace_probes[i]) == NULL ||
                                  dtrace_match_probe(probe, pkp, priv, uid,
                                  zoneid) <= 0)
                                        continue;

                              nmatched++;

                              if ((rc = (*matched)(probe, arg)) !=
                                  DTRACE_MATCH_NEXT) {
                                        if (rc == DTRACE_MATCH_FAIL)
                                                  return (DTRACE_MATCH_FAIL);
                                        break;
                              }
                    }

                    return (nmatched);
          }

          /*
           * If we selected a hash table, iterate over each probe of the same key
           * name and invoke the callback for every probe that matches the other
           * attributes of our input probe key.
           */
          for (probe = dtrace_hash_lookup(hash, &template); probe != NULL;
              probe = *(DTRACE_HASHNEXT(hash, probe))) {

                    if (dtrace_match_probe(probe, pkp, priv, uid, zoneid) <= 0)
                              continue;

                    nmatched++;

                    if ((rc = (*matched)(probe, arg)) != DTRACE_MATCH_NEXT) {
                              if (rc == DTRACE_MATCH_FAIL)
                                        return (DTRACE_MATCH_FAIL);
                              break;
                    }
          }

          return (nmatched);
}

/*
 * Return the function pointer dtrace_probecmp() should use to compare the
 * specified pattern with a string.  For NULL or empty patterns, we select
 * dtrace_match_nul().  For glob pattern strings, we use dtrace_match_glob().
 * For non-empty non-glob strings, we use dtrace_match_string().
 */
static dtrace_probekey_f *
dtrace_probekey_func(const char *p)
{
          char c;

          if (p == NULL || *p == '\0')
                    return (&dtrace_match_nul);

          while ((c = *p++) != '\0') {
                    if (c == '[' || c == '?' || c == '*' || c == '\\')
                              return (&dtrace_match_glob);
          }

          return (&dtrace_match_string);
}

/*
 * Build a probe comparison key for use with dtrace_match_probe() from the
 * given probe description.  By convention, a null key only matches anchored
 * probes: if each field is the empty string, reset dtpk_fmatch to
 * dtrace_match_nonzero().
 */
static void
dtrace_probekey(dtrace_probedesc_t *pdp, dtrace_probekey_t *pkp)
{
          pkp->dtpk_prov = pdp->dtpd_provider;
          pkp->dtpk_pmatch = dtrace_probekey_func(pdp->dtpd_provider);

          pkp->dtpk_mod = pdp->dtpd_mod;
          pkp->dtpk_mmatch = dtrace_probekey_func(pdp->dtpd_mod);

          pkp->dtpk_func = pdp->dtpd_func;
          pkp->dtpk_fmatch = dtrace_probekey_func(pdp->dtpd_func);

          pkp->dtpk_name = pdp->dtpd_name;
          pkp->dtpk_nmatch = dtrace_probekey_func(pdp->dtpd_name);

          pkp->dtpk_id = pdp->dtpd_id;

          if (pkp->dtpk_id == DTRACE_IDNONE &&
              pkp->dtpk_pmatch == &dtrace_match_nul &&
              pkp->dtpk_mmatch == &dtrace_match_nul &&
              pkp->dtpk_fmatch == &dtrace_match_nul &&
              pkp->dtpk_nmatch == &dtrace_match_nul)
                    pkp->dtpk_fmatch = &dtrace_match_nonzero;
}

/*
 * DTrace Provider-to-Framework API Functions
 *
 * These functions implement much of the Provider-to-Framework API, as
 * described in <sys/dtrace.h>.  The parts of the API not in this section are
 * the functions in the API for probe management (found below), and
 * dtrace_probe() itself (found above).
 */

/*
 * Register the calling provider with the DTrace framework.  This should
 * generally be called by DTrace providers in their attach(9E) entry point.
 */
int
dtrace_register(const char *name, const dtrace_pattr_t *pap, uint32_t priv,
    cred_t *cr, const dtrace_pops_t *pops, void *arg, dtrace_provider_id_t *idp)
{
          dtrace_provider_t *provider;

          if (name == NULL || pap == NULL || pops == NULL || idp == NULL) {
                    cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                        "arguments", name ? name : "<NULL>");
                    return (EINVAL);
          }

          if (name[0] == '\0' || dtrace_badname(name)) {
                    cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                        "provider name", name);
                    return (EINVAL);
          }

          if ((pops->dtps_provide == NULL && pops->dtps_provide_module == NULL) ||
              pops->dtps_enable == NULL || pops->dtps_disable == NULL ||
              pops->dtps_destroy == NULL ||
              ((pops->dtps_resume == NULL) != (pops->dtps_suspend == NULL))) {
                    cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                        "provider ops", name);
                    return (EINVAL);
          }

          if (dtrace_badattr(&pap->dtpa_provider) ||
              dtrace_badattr(&pap->dtpa_mod) ||
              dtrace_badattr(&pap->dtpa_func) ||
              dtrace_badattr(&pap->dtpa_name) ||
              dtrace_badattr(&pap->dtpa_args)) {
                    cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                        "provider attributes", name);
                    return (EINVAL);
          }

          if (priv & ~DTRACE_PRIV_ALL) {
                    cmn_err(CE_WARN, "failed to register provider '%s': invalid "
                        "privilege attributes", name);
                    return (EINVAL);
          }

          if ((priv & DTRACE_PRIV_KERNEL) &&
              (priv & (DTRACE_PRIV_USER | DTRACE_PRIV_OWNER)) &&
              pops->dtps_usermode == NULL) {
                    cmn_err(CE_WARN, "failed to register provider '%s': need "
                        "dtps_usermode() op for given privilege attributes", name);
                    return (EINVAL);
          }

          provider = kmem_zalloc(sizeof (dtrace_provider_t), KM_SLEEP);
          provider->dtpv_name = kmem_alloc(strlen(name) + 1, KM_SLEEP);
          (void) strcpy(provider->dtpv_name, name);

          provider->dtpv_attr = *pap;
          provider->dtpv_priv.dtpp_flags = priv;
          if (cr != NULL) {
                    provider->dtpv_priv.dtpp_uid = crgetuid(cr);
                    provider->dtpv_priv.dtpp_zoneid = crgetzoneid(cr);
          }
          provider->dtpv_pops = *pops;

          if (pops->dtps_provide == NULL) {
                    ASSERT(pops->dtps_provide_module != NULL);
                    provider->dtpv_pops.dtps_provide =
                        (void (*)(void *, dtrace_probedesc_t *))dtrace_nullop;
          }

          if (pops->dtps_provide_module == NULL) {
                    ASSERT(pops->dtps_provide != NULL);
                    provider->dtpv_pops.dtps_provide_module =
                        (void (*)(void *, modctl_t *))dtrace_nullop;
          }

          if (pops->dtps_suspend == NULL) {
                    ASSERT(pops->dtps_resume == NULL);
                    provider->dtpv_pops.dtps_suspend =
                        (void (*)(void *, dtrace_id_t, void *))dtrace_nullop;
                    provider->dtpv_pops.dtps_resume =
                        (void (*)(void *, dtrace_id_t, void *))dtrace_nullop;
          }

          provider->dtpv_arg = arg;
          *idp = (dtrace_provider_id_t)provider;

          if (pops == &dtrace_provider_ops) {
                    ASSERT(MUTEX_HELD(&dtrace_provider_lock));
                    ASSERT(MUTEX_HELD(&dtrace_lock));
                    ASSERT(dtrace_anon.dta_enabling == NULL);

                    /*
                     * We make sure that the DTrace provider is at the head of
                     * the provider chain.
                     */
                    provider->dtpv_next = dtrace_provider;
                    dtrace_provider = provider;
                    return (0);
          }

          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);

          /*
           * If there is at least one provider registered, we'll add this
           * provider after the first provider.
           */
          if (dtrace_provider != NULL) {
                    provider->dtpv_next = dtrace_provider->dtpv_next;
                    dtrace_provider->dtpv_next = provider;
          } else {
                    dtrace_provider = provider;
          }

          if (dtrace_retained != NULL) {
                    dtrace_enabling_provide(provider);

                    /*
                     * Now we need to call dtrace_enabling_matchall() -- which
                     * will acquire cpu_lock and dtrace_lock.  We therefore need
                     * to drop all of our locks before calling into it...
                     */
                    mutex_exit(&dtrace_lock);
                    mutex_exit(&dtrace_provider_lock);
                    dtrace_enabling_matchall();

                    return (0);
          }

          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);

          return (0);
}

/*
 * Unregister the specified provider from the DTrace framework.  This should
 * generally be called by DTrace providers in their detach(9E) entry point.
 */
int
dtrace_unregister(dtrace_provider_id_t id)
{
          dtrace_provider_t *old = (dtrace_provider_t *)id;
          dtrace_provider_t *prev = NULL;
          int i, self = 0, noreap = 0;
          dtrace_probe_t *probe, *first = NULL;

          if (old->dtpv_pops.dtps_enable ==
              (int (*)(void *, dtrace_id_t, void *))dtrace_nullop) {
                    /*
                     * If DTrace itself is the provider, we're called with locks
                     * already held.
                     */
                    ASSERT(old == dtrace_provider);
#ifdef illumos
                    ASSERT(dtrace_devi != NULL);
#endif
                    ASSERT(MUTEX_HELD(&dtrace_provider_lock));
                    ASSERT(MUTEX_HELD(&dtrace_lock));
                    self = 1;

                    if (dtrace_provider->dtpv_next != NULL) {
                              /*
                               * There's another provider here; return failure.
                               */
                              return (EBUSY);
                    }
          } else {
                    mutex_enter(&dtrace_provider_lock);
#ifdef illumos
                    mutex_enter(&mod_lock);
#endif
                    mutex_enter(&dtrace_lock);
          }

          /*
           * If anyone has /dev/dtrace open, or if there are anonymous enabled
           * probes, we refuse to let providers slither away, unless this
           * provider has already been explicitly invalidated.
           */
          if (!old->dtpv_defunct &&
              (dtrace_opens || (dtrace_anon.dta_state != NULL &&
              dtrace_anon.dta_state->dts_necbs > 0))) {
                    if (!self) {
                              mutex_exit(&dtrace_lock);
#ifdef illumos
                              mutex_exit(&mod_lock);
#endif
                              mutex_exit(&dtrace_provider_lock);
                    }
                    return (EBUSY);
          }

          /*
           * Attempt to destroy the probes associated with this provider.
           */
          for (i = 0; i < dtrace_nprobes; i++) {
                    if ((probe = dtrace_probes[i]) == NULL)
                              continue;

                    if (probe->dtpr_provider != old)
                              continue;

                    if (probe->dtpr_ecb == NULL)
                              continue;

                    /*
                     * If we are trying to unregister a defunct provider, and the
                     * provider was made defunct within the interval dictated by
                     * dtrace_unregister_defunct_reap, we'll (asynchronously)
                     * attempt to reap our enablings.  To denote that the provider
                     * should reattempt to unregister itself at some point in the
                     * future, we will return a differentiable error code (EAGAIN
                     * instead of EBUSY) in this case.
                     */
                    if (dtrace_gethrtime() - old->dtpv_defunct >
                        dtrace_unregister_defunct_reap)
                              noreap = 1;

                    /*
                     * We have at least one ECB; we can't remove this provider.
                     */
                    if (!self) {
                              mutex_exit(&dtrace_lock);
#ifdef illumos
                              mutex_exit(&mod_lock);
#endif
                              mutex_exit(&dtrace_provider_lock);
                    }

                    if (noreap)
                              return (EBUSY);

                    (void) taskq_dispatch(dtrace_taskq,
                        (task_func_t *)dtrace_enabling_reap, NULL, TQ_SLEEP);

                    return (EAGAIN);
          }

          /*
           * All of the probes for this provider are disabled; we can safely
           * remove all of them from their hash chains and from the probe array.
           */
          for (i = 0; i < dtrace_nprobes; i++) {
                    if ((probe = dtrace_probes[i]) == NULL)
                              continue;

                    if (probe->dtpr_provider != old)
                              continue;

                    dtrace_probes[i] = NULL;

                    dtrace_hash_remove(dtrace_bymod, probe);
                    dtrace_hash_remove(dtrace_byfunc, probe);
                    dtrace_hash_remove(dtrace_byname, probe);

                    if (first == NULL) {
                              first = probe;
                              probe->dtpr_nextmod = NULL;
                    } else {
                              probe->dtpr_nextmod = first;
                              first = probe;
                    }
          }

          /*
           * The provider's probes have been removed from the hash chains and
           * from the probe array.  Now issue a dtrace_sync() to be sure that
           * everyone has cleared out from any probe array processing.
           */
          dtrace_sync();

          for (probe = first; probe != NULL; probe = first) {
                    first = probe->dtpr_nextmod;

                    old->dtpv_pops.dtps_destroy(old->dtpv_arg, probe->dtpr_id,
                        probe->dtpr_arg);
                    kmem_free(probe->dtpr_mod, strlen(probe->dtpr_mod) + 1);
                    kmem_free(probe->dtpr_func, strlen(probe->dtpr_func) + 1);
                    kmem_free(probe->dtpr_name, strlen(probe->dtpr_name) + 1);
#ifdef illumos
                    vmem_free(dtrace_arena, (void *)(uintptr_t)(probe->dtpr_id), 1);
#endif
#ifdef __FreeBSD__
                    free_unr(dtrace_arena, probe->dtpr_id);
#endif
#ifdef __NetBSD__
                    vmem_free(dtrace_arena, (uintptr_t)(probe->dtpr_id), 1);
#endif
                    kmem_free(probe, sizeof (dtrace_probe_t));
          }

          if ((prev = dtrace_provider) == old) {
#ifdef illumos
                    ASSERT(self || dtrace_devi == NULL);
                    ASSERT(old->dtpv_next == NULL || dtrace_devi == NULL);
#endif
                    dtrace_provider = old->dtpv_next;
          } else {
                    while (prev != NULL && prev->dtpv_next != old)
                              prev = prev->dtpv_next;

                    if (prev == NULL) {
                              panic("attempt to unregister non-existent "
                                  "dtrace provider %p\n", (void *)id);
                    }

                    prev->dtpv_next = old->dtpv_next;
          }

          if (!self) {
                    mutex_exit(&dtrace_lock);
#ifdef illumos
                    mutex_exit(&mod_lock);
#endif
                    mutex_exit(&dtrace_provider_lock);
          }

          kmem_free(old->dtpv_name, strlen(old->dtpv_name) + 1);
          kmem_free(old, sizeof (dtrace_provider_t));

          return (0);
}

/*
 * Invalidate the specified provider.  All subsequent probe lookups for the
 * specified provider will fail, but its probes will not be removed.
 */
void
dtrace_invalidate(dtrace_provider_id_t id)
{
          dtrace_provider_t *pvp = (dtrace_provider_t *)id;

          ASSERT(pvp->dtpv_pops.dtps_enable !=
              (int (*)(void *, dtrace_id_t, void *))dtrace_nullop);

          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);

          pvp->dtpv_defunct = dtrace_gethrtime();

          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);
}

/*
 * Indicate whether or not DTrace has attached.
 */
int
dtrace_attached(void)
{
          /*
           * dtrace_provider will be non-NULL iff the DTrace driver has
           * attached.  (It's non-NULL because DTrace is always itself a
           * provider.)
           */
          return (dtrace_provider != NULL);
}

/*
 * Remove all the unenabled probes for the given provider.  This function is
 * not unlike dtrace_unregister(), except that it doesn't remove the provider
 * -- just as many of its associated probes as it can.
 */
int
dtrace_condense(dtrace_provider_id_t id)
{
          dtrace_provider_t *prov = (dtrace_provider_t *)id;
          int i;
          dtrace_probe_t *probe;

          /*
           * Make sure this isn't the dtrace provider itself.
           */
          ASSERT(prov->dtpv_pops.dtps_enable !=
              (int (*)(void *, dtrace_id_t, void *))dtrace_nullop);

          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);

          /*
           * Attempt to destroy the probes associated with this provider.
           */
          for (i = 0; i < dtrace_nprobes; i++) {
                    if ((probe = dtrace_probes[i]) == NULL)
                              continue;

                    if (probe->dtpr_provider != prov)
                              continue;

                    if (probe->dtpr_ecb != NULL)
                              continue;

                    dtrace_probes[i] = NULL;

                    dtrace_hash_remove(dtrace_bymod, probe);
                    dtrace_hash_remove(dtrace_byfunc, probe);
                    dtrace_hash_remove(dtrace_byname, probe);

                    prov->dtpv_pops.dtps_destroy(prov->dtpv_arg, i + 1,
                        probe->dtpr_arg);
                    kmem_free(probe->dtpr_mod, strlen(probe->dtpr_mod) + 1);
                    kmem_free(probe->dtpr_func, strlen(probe->dtpr_func) + 1);
                    kmem_free(probe->dtpr_name, strlen(probe->dtpr_name) + 1);
                    kmem_free(probe, sizeof (dtrace_probe_t));
#ifdef illumos
                    vmem_free(dtrace_arena, (void *)((uintptr_t)i + 1), 1);
#endif
#ifdef __FreeBSD__
                    free_unr(dtrace_arena, i + 1);
#endif
#ifdef __NetBSD__
                    vmem_free(dtrace_arena, ((uintptr_t)i + 1), 1);
#endif
          }

          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);

          return (0);
}

/*
 * DTrace Probe Management Functions
 *
 * The functions in this section perform the DTrace probe management,
 * including functions to create probes, look-up probes, and call into the
 * providers to request that probes be provided.  Some of these functions are
 * in the Provider-to-Framework API; these functions can be identified by the
 * fact that they are not declared "static".
 */

/*
 * Create a probe with the specified module name, function name, and name.
 */
dtrace_id_t
dtrace_probe_create(dtrace_provider_id_t prov, const char *mod,
    const char *func, const char *name, int aframes, void *arg)
{
          dtrace_probe_t *probe, **probes;
          dtrace_provider_t *provider = (dtrace_provider_t *)prov;
          dtrace_id_t id;

          if (provider == dtrace_provider) {
                    ASSERT(MUTEX_HELD(&dtrace_lock));
          } else {
                    mutex_enter(&dtrace_lock);
          }

#ifdef illumos
          id = (dtrace_id_t)(uintptr_t)vmem_alloc(dtrace_arena, 1,
              VM_BESTFIT | VM_SLEEP);
#endif
#ifdef __FreeBSD__
          id = alloc_unr(dtrace_arena);
#endif
#ifdef __NetBSD__
          vmem_addr_t offset;
          if (vmem_alloc(dtrace_arena, 1, VM_BESTFIT | VM_SLEEP, &offset) != 0)
                    ASSERT(0);
          id = (dtrace_id_t)(uintptr_t)offset;
#endif
          probe = kmem_zalloc(sizeof (dtrace_probe_t), KM_SLEEP);

          probe->dtpr_id = id;
          probe->dtpr_gen = dtrace_probegen++;
          probe->dtpr_mod = dtrace_strdup(mod);
          probe->dtpr_func = dtrace_strdup(func);
          probe->dtpr_name = dtrace_strdup(name);
          probe->dtpr_arg = arg;
          probe->dtpr_aframes = aframes;
          probe->dtpr_provider = provider;

          dtrace_hash_add(dtrace_bymod, probe);
          dtrace_hash_add(dtrace_byfunc, probe);
          dtrace_hash_add(dtrace_byname, probe);

          if (id - 1 >= dtrace_nprobes) {
                    size_t osize = dtrace_nprobes * sizeof (dtrace_probe_t *);
                    size_t nsize = osize << 1;

                    if (nsize == 0) {
                              ASSERT(osize == 0);
                              ASSERT(dtrace_probes == NULL);
                              nsize = sizeof (dtrace_probe_t *);
                    }

                    probes = kmem_zalloc(nsize, KM_SLEEP);

                    if (dtrace_probes == NULL) {
                              ASSERT(osize == 0);
                              dtrace_probes = probes;
                              dtrace_nprobes = 1;
                    } else {
                              dtrace_probe_t **oprobes = dtrace_probes;

                              bcopy(oprobes, probes, osize);
                              dtrace_membar_producer();
                              dtrace_probes = probes;

                              dtrace_sync();

                              /*
                               * All CPUs are now seeing the new probes array; we can
                               * safely free the old array.
                               */
                              kmem_free(oprobes, osize);
                              dtrace_nprobes <<= 1;
                    }

                    ASSERT(id - 1 < dtrace_nprobes);
          }

          ASSERT(dtrace_probes[id - 1] == NULL);
          dtrace_probes[id - 1] = probe;

          if (provider != dtrace_provider)
                    mutex_exit(&dtrace_lock);

          return (id);
}

static dtrace_probe_t *
dtrace_probe_lookup_id(dtrace_id_t id)
{
          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (id == 0 || id > dtrace_nprobes)
                    return (NULL);

          return (dtrace_probes[id - 1]);
}

static int
dtrace_probe_lookup_match(dtrace_probe_t *probe, void *arg)
{
          *((dtrace_id_t *)arg) = probe->dtpr_id;

          return (DTRACE_MATCH_DONE);
}

/*
 * Look up a probe based on provider and one or more of module name, function
 * name and probe name.
 */
dtrace_id_t
dtrace_probe_lookup(dtrace_provider_id_t prid, char *mod,
    char *func, char *name)
{
          dtrace_probekey_t pkey;
          dtrace_id_t id;
          int match;

          pkey.dtpk_prov = ((dtrace_provider_t *)prid)->dtpv_name;
          pkey.dtpk_pmatch = &dtrace_match_string;
          pkey.dtpk_mod = mod;
          pkey.dtpk_mmatch = mod ? &dtrace_match_string : &dtrace_match_nul;
          pkey.dtpk_func = func;
          pkey.dtpk_fmatch = func ? &dtrace_match_string : &dtrace_match_nul;
          pkey.dtpk_name = name;
          pkey.dtpk_nmatch = name ? &dtrace_match_string : &dtrace_match_nul;
          pkey.dtpk_id = DTRACE_IDNONE;

          mutex_enter(&dtrace_lock);
          match = dtrace_match(&pkey, DTRACE_PRIV_ALL, 0, 0,
              dtrace_probe_lookup_match, &id);
          mutex_exit(&dtrace_lock);

          ASSERT(match == 1 || match == 0);
          return (match ? id : 0);
}

/*
 * Returns the probe argument associated with the specified probe.
 */
void *
dtrace_probe_arg(dtrace_provider_id_t id, dtrace_id_t pid)
{
          dtrace_probe_t *probe;
          void *rval = NULL;

          mutex_enter(&dtrace_lock);

          if ((probe = dtrace_probe_lookup_id(pid)) != NULL &&
              probe->dtpr_provider == (dtrace_provider_t *)id)
                    rval = probe->dtpr_arg;

          mutex_exit(&dtrace_lock);

          return (rval);
}

/*
 * Copy a probe into a probe description.
 */
static void
dtrace_probe_description(const dtrace_probe_t *prp, dtrace_probedesc_t *pdp)
{
          bzero(pdp, sizeof (dtrace_probedesc_t));
          pdp->dtpd_id = prp->dtpr_id;

          (void) strncpy(pdp->dtpd_provider,
              prp->dtpr_provider->dtpv_name, DTRACE_PROVNAMELEN - 1);

          (void) strncpy(pdp->dtpd_mod, prp->dtpr_mod, DTRACE_MODNAMELEN - 1);
          (void) strncpy(pdp->dtpd_func, prp->dtpr_func, DTRACE_FUNCNAMELEN - 1);
          (void) strncpy(pdp->dtpd_name, prp->dtpr_name, DTRACE_NAMELEN - 1);
}

/*
 * Called to indicate that a probe -- or probes -- should be provided by a
 * specfied provider.  If the specified description is NULL, the provider will
 * be told to provide all of its probes.  (This is done whenever a new
 * consumer comes along, or whenever a retained enabling is to be matched.) If
 * the specified description is non-NULL, the provider is given the
 * opportunity to dynamically provide the specified probe, allowing providers
 * to support the creation of probes on-the-fly.  (So-called _autocreated_
 * probes.)  If the provider is NULL, the operations will be applied to all
 * providers; if the provider is non-NULL the operations will only be applied
 * to the specified provider.  The dtrace_provider_lock must be held, and the
 * dtrace_lock must _not_ be held -- the provider's dtps_provide() operation
 * will need to grab the dtrace_lock when it reenters the framework through
 * dtrace_probe_lookup(), dtrace_probe_create(), etc.
 */
static void
dtrace_probe_provide(dtrace_probedesc_t *desc, dtrace_provider_t *prv)
{
#ifdef illumos
          modctl_t *ctl;
#endif
#ifdef __NetBSD__
          module_t *mod;
#endif
          int all = 0;

          ASSERT(MUTEX_HELD(&dtrace_provider_lock));

          if (prv == NULL) {
                    all = 1;
                    prv = dtrace_provider;
          }

          do {
                    /*
                     * First, call the blanket provide operation.
                     */
                    prv->dtpv_pops.dtps_provide(prv->dtpv_arg, desc);

#ifdef illumos
                    /*
                     * Now call the per-module provide operation.  We will grab
                     * mod_lock to prevent the list from being modified.  Note
                     * that this also prevents the mod_busy bits from changing.
                     * (mod_busy can only be changed with mod_lock held.)
                     */
                    mutex_enter(&mod_lock);

                    ctl = &modules;
                    do {
                              if (ctl->mod_busy || ctl->mod_mp == NULL)
                                        continue;

                              prv->dtpv_pops.dtps_provide_module(prv->dtpv_arg, ctl);

                    } while ((ctl = ctl->mod_next) != &modules);

                    mutex_exit(&mod_lock);
#endif
#ifdef __NetBSD__
                    kernconfig_lock();

                    /* Fake netbsd module first */
                    prv->dtpv_pops.dtps_provide_module(prv->dtpv_arg, module_kernel());

                    TAILQ_FOREACH(mod, &module_list, mod_chain) {
                              if (module_source(mod) != MODULE_SOURCE_KERNEL)
                                        prv->dtpv_pops.dtps_provide_module(prv->dtpv_arg, mod);
                    }
                    kernconfig_unlock();
#endif
          } while (all && (prv = prv->dtpv_next) != NULL);
}

#ifdef illumos
/*
 * Iterate over each probe, and call the Framework-to-Provider API function
 * denoted by offs.
 */
static void
dtrace_probe_foreach(uintptr_t offs)
{
          dtrace_provider_t *prov;
          void (*func)(void *, dtrace_id_t, void *);
          dtrace_probe_t *probe;
          dtrace_icookie_t cookie;
          int i;

          /*
           * We disable interrupts to walk through the probe array.  This is
           * safe -- the dtrace_sync() in dtrace_unregister() assures that we
           * won't see stale data.
           */
          cookie = dtrace_interrupt_disable();

          for (i = 0; i < dtrace_nprobes; i++) {
                    if ((probe = dtrace_probes[i]) == NULL)
                              continue;

                    if (probe->dtpr_ecb == NULL) {
                              /*
                               * This probe isn't enabled -- don't call the function.
                               */
                              continue;
                    }

                    prov = probe->dtpr_provider;
                    func = *((void(**)(void *, dtrace_id_t, void *))
                        ((uintptr_t)&prov->dtpv_pops + offs));

                    func(prov->dtpv_arg, i + 1, probe->dtpr_arg);
          }

          dtrace_interrupt_enable(cookie);
}
#endif

static int
dtrace_probe_enable(dtrace_probedesc_t *desc, dtrace_enabling_t *enab)
{
          dtrace_probekey_t pkey;
          uint32_t priv;
          uid_t uid;
          zoneid_t zoneid;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          dtrace_ecb_create_cache = NULL;

          if (desc == NULL) {
                    /*
                     * If we're passed a NULL description, we're being asked to
                     * create an ECB with a NULL probe.
                     */
                    (void) dtrace_ecb_create_enable(NULL, enab);
                    return (0);
          }

          dtrace_probekey(desc, &pkey);
          dtrace_cred2priv(enab->dten_vstate->dtvs_state->dts_cred.dcr_cred,
              &priv, &uid, &zoneid);

          return (dtrace_match(&pkey, priv, uid, zoneid, dtrace_ecb_create_enable,
              enab));
}

/*
 * DTrace Helper Provider Functions
 */
static void
dtrace_dofattr2attr(dtrace_attribute_t *attr, const dof_attr_t dofattr)
{
          attr->dtat_name = DOF_ATTR_NAME(dofattr);
          attr->dtat_data = DOF_ATTR_DATA(dofattr);
          attr->dtat_class = DOF_ATTR_CLASS(dofattr);
}

static void
dtrace_dofprov2hprov(dtrace_helper_provdesc_t *hprov,
    const dof_provider_t *dofprov, char *strtab)
{
          hprov->dthpv_provname = strtab + dofprov->dofpv_name;
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_provider,
              dofprov->dofpv_provattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_mod,
              dofprov->dofpv_modattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_func,
              dofprov->dofpv_funcattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_name,
              dofprov->dofpv_nameattr);
          dtrace_dofattr2attr(&hprov->dthpv_pattr.dtpa_args,
              dofprov->dofpv_argsattr);
}

static void
dtrace_helper_provide_one(dof_helper_t *dhp, dof_sec_t *sec, pid_t pid)
{
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          dof_sec_t *str_sec, *prb_sec, *arg_sec, *off_sec, *enoff_sec;
          dof_provider_t *provider;
          dof_probe_t *probe;
          uint32_t *off, *enoff;
          uint8_t *arg;
          char *strtab;
          uint_t i, nprobes;
          dtrace_helper_provdesc_t dhpv;
          dtrace_helper_probedesc_t dhpb;
          dtrace_meta_t *meta = dtrace_meta_pid;
          dtrace_mops_t *mops = &meta->dtm_mops;
          void *parg;

          provider = (dof_provider_t *)(uintptr_t)(daddr + sec->dofs_offset);
          str_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_strtab * dof->dofh_secsize);
          prb_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_probes * dof->dofh_secsize);
          arg_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_prargs * dof->dofh_secsize);
          off_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_proffs * dof->dofh_secsize);

          strtab = (char *)(uintptr_t)(daddr + str_sec->dofs_offset);
          off = (uint32_t *)(uintptr_t)(daddr + off_sec->dofs_offset);
          arg = (uint8_t *)(uintptr_t)(daddr + arg_sec->dofs_offset);
          enoff = NULL;

          /*
           * See dtrace_helper_provider_validate().
           */
          if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1 &&
              provider->dofpv_prenoffs != DOF_SECT_NONE) {
                    enoff_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
                        provider->dofpv_prenoffs * dof->dofh_secsize);
                    enoff = (uint32_t *)(uintptr_t)(daddr + enoff_sec->dofs_offset);
          }

          nprobes = prb_sec->dofs_size / prb_sec->dofs_entsize;

          /*
           * Create the provider.
           */
          dtrace_dofprov2hprov(&dhpv, provider, strtab);

          if ((parg = mops->dtms_provide_pid(meta->dtm_arg, &dhpv, pid)) == NULL)
                    return;

          meta->dtm_count++;

          /*
           * Create the probes.
           */
          for (i = 0; i < nprobes; i++) {
                    probe = (dof_probe_t *)(uintptr_t)(daddr +
                        prb_sec->dofs_offset + i * prb_sec->dofs_entsize);

                    /* See the check in dtrace_helper_provider_validate(). */
                    if (strlen(strtab + probe->dofpr_func) >= DTRACE_FUNCNAMELEN)
                              continue;

                    dhpb.dthpb_mod = dhp->dofhp_mod;
                    dhpb.dthpb_func = strtab + probe->dofpr_func;
                    dhpb.dthpb_name = strtab + probe->dofpr_name;
                    dhpb.dthpb_base = probe->dofpr_addr;
                    dhpb.dthpb_offs = off + probe->dofpr_offidx;
                    dhpb.dthpb_noffs = probe->dofpr_noffs;
                    if (enoff != NULL) {
                              dhpb.dthpb_enoffs = enoff + probe->dofpr_enoffidx;
                              dhpb.dthpb_nenoffs = probe->dofpr_nenoffs;
                    } else {
                              dhpb.dthpb_enoffs = NULL;
                              dhpb.dthpb_nenoffs = 0;
                    }
                    dhpb.dthpb_args = arg + probe->dofpr_argidx;
                    dhpb.dthpb_nargc = probe->dofpr_nargc;
                    dhpb.dthpb_xargc = probe->dofpr_xargc;
                    dhpb.dthpb_ntypes = strtab + probe->dofpr_nargv;
                    dhpb.dthpb_xtypes = strtab + probe->dofpr_xargv;

                    mops->dtms_create_probe(meta->dtm_arg, parg, &dhpb);
          }
}

static void
dtrace_helper_provide(dof_helper_t *dhp, pid_t pid)
{
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          int i;

          ASSERT(MUTEX_HELD(&dtrace_meta_lock));

          for (i = 0; i < dof->dofh_secnum; i++) {
                    dof_sec_t *sec = (dof_sec_t *)(uintptr_t)(daddr +
                        dof->dofh_secoff + i * dof->dofh_secsize);

                    if (sec->dofs_type != DOF_SECT_PROVIDER)
                              continue;

                    dtrace_helper_provide_one(dhp, sec, pid);
          }

          /*
           * We may have just created probes, so we must now rematch against
           * any retained enablings.  Note that this call will acquire both
           * cpu_lock and dtrace_lock; the fact that we are holding
           * dtrace_meta_lock now is what defines the ordering with respect to
           * these three locks.
           */
          dtrace_enabling_matchall();
}

static void
dtrace_helper_provider_remove_one(dof_helper_t *dhp, dof_sec_t *sec, pid_t pid)
{
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          dof_sec_t *str_sec;
          dof_provider_t *provider;
          char *strtab;
          dtrace_helper_provdesc_t dhpv;
          dtrace_meta_t *meta = dtrace_meta_pid;
          dtrace_mops_t *mops = &meta->dtm_mops;

          provider = (dof_provider_t *)(uintptr_t)(daddr + sec->dofs_offset);
          str_sec = (dof_sec_t *)(uintptr_t)(daddr + dof->dofh_secoff +
              provider->dofpv_strtab * dof->dofh_secsize);

          strtab = (char *)(uintptr_t)(daddr + str_sec->dofs_offset);

          /*
           * Create the provider.
           */
          dtrace_dofprov2hprov(&dhpv, provider, strtab);

          mops->dtms_remove_pid(meta->dtm_arg, &dhpv, pid);

          meta->dtm_count--;
}

static void
dtrace_helper_provider_remove(dof_helper_t *dhp, pid_t pid)
{
          uintptr_t daddr = (uintptr_t)dhp->dofhp_dof;
          dof_hdr_t *dof = (dof_hdr_t *)daddr;
          int i;

          ASSERT(MUTEX_HELD(&dtrace_meta_lock));

          for (i = 0; i < dof->dofh_secnum; i++) {
                    dof_sec_t *sec = (dof_sec_t *)(uintptr_t)(daddr +
                        dof->dofh_secoff + i * dof->dofh_secsize);

                    if (sec->dofs_type != DOF_SECT_PROVIDER)
                              continue;

                    dtrace_helper_provider_remove_one(dhp, sec, pid);
          }
}

/*
 * DTrace Meta Provider-to-Framework API Functions
 *
 * These functions implement the Meta Provider-to-Framework API, as described
 * in <sys/dtrace.h>.
 */
int
dtrace_meta_register(const char *name, const dtrace_mops_t *mops, void *arg,
    dtrace_meta_provider_id_t *idp)
{
          dtrace_meta_t *meta;
          dtrace_helpers_t *help, *next;
          int i;

          *idp = DTRACE_METAPROVNONE;

          /*
           * We strictly don't need the name, but we hold onto it for
           * debuggability. All hail error queues!
           */
          if (name == NULL) {
                    cmn_err(CE_WARN, "failed to register meta-provider: "
                        "invalid name");
                    return (EINVAL);
          }

          if (mops == NULL ||
              mops->dtms_create_probe == NULL ||
              mops->dtms_provide_pid == NULL ||
              mops->dtms_remove_pid == NULL) {
                    cmn_err(CE_WARN, "failed to register meta-register %s: "
                        "invalid ops", name);
                    return (EINVAL);
          }

          meta = kmem_zalloc(sizeof (dtrace_meta_t), KM_SLEEP);
          meta->dtm_mops = *mops;
          meta->dtm_name = kmem_alloc(strlen(name) + 1, KM_SLEEP);
          (void) strcpy(meta->dtm_name, name);
          meta->dtm_arg = arg;

          mutex_enter(&dtrace_meta_lock);
          mutex_enter(&dtrace_lock);

          if (dtrace_meta_pid != NULL) {
                    mutex_exit(&dtrace_lock);
                    mutex_exit(&dtrace_meta_lock);
                    cmn_err(CE_WARN, "failed to register meta-register %s: "
                        "user-land meta-provider exists", name);
                    kmem_free(meta->dtm_name, strlen(meta->dtm_name) + 1);
                    kmem_free(meta, sizeof (dtrace_meta_t));
                    return (EINVAL);
          }

          dtrace_meta_pid = meta;
          *idp = (dtrace_meta_provider_id_t)meta;

          /*
           * If there are providers and probes ready to go, pass them
           * off to the new meta provider now.
           */

          help = dtrace_deferred_pid;
          dtrace_deferred_pid = NULL;

          mutex_exit(&dtrace_lock);

          while (help != NULL) {
                    for (i = 0; i < help->dthps_nprovs; i++) {
                              dtrace_helper_provide(&help->dthps_provs[i]->dthp_prov,
                                  help->dthps_pid);
                    }

                    next = help->dthps_next;
                    help->dthps_next = NULL;
                    help->dthps_prev = NULL;
                    help->dthps_deferred = 0;
                    help = next;
          }

          mutex_exit(&dtrace_meta_lock);

          return (0);
}

int
dtrace_meta_unregister(dtrace_meta_provider_id_t id)
{
          dtrace_meta_t **pp, *old = (dtrace_meta_t *)id;

          mutex_enter(&dtrace_meta_lock);
          mutex_enter(&dtrace_lock);

          if (old == dtrace_meta_pid) {
                    pp = &dtrace_meta_pid;
          } else {
                    panic("attempt to unregister non-existent "
                        "dtrace meta-provider %p\n", (void *)old);
          }

          if (old->dtm_count != 0) {
                    mutex_exit(&dtrace_lock);
                    mutex_exit(&dtrace_meta_lock);
                    return (EBUSY);
          }

          *pp = NULL;

          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_meta_lock);

          kmem_free(old->dtm_name, strlen(old->dtm_name) + 1);
          kmem_free(old, sizeof (dtrace_meta_t));

          return (0);
}


/*
 * DTrace DIF Object Functions
 */
static int
dtrace_difo_err(uint_t pc, const char *format, ...)
{
          if (dtrace_err_verbose) {
                    va_list alist;

                    (void) uprintf("dtrace DIF object error: [%u]: ", pc);
                    va_start(alist, format);
                    (void) vuprintf(format, alist);
                    va_end(alist);
          }

#ifdef DTRACE_ERRDEBUG
          dtrace_errdebug(format);
#endif
          return (1);
}

/*
 * Validate a DTrace DIF object by checking the IR instructions.  The following
 * rules are currently enforced by dtrace_difo_validate():
 *
 * 1. Each instruction must have a valid opcode
 * 2. Each register, string, variable, or subroutine reference must be valid
 * 3. No instruction can modify register %r0 (must be zero)
 * 4. All instruction reserved bits must be set to zero
 * 5. The last instruction must be a "ret" instruction
 * 6. All branch targets must reference a valid instruction _after_ the branch
 */
static int
dtrace_difo_validate(dtrace_difo_t *dp, dtrace_vstate_t *vstate, uint_t nregs,
    cred_t *cr)
{
          int err = 0, i;
          int (*efunc)(uint_t pc, const char *, ...) = dtrace_difo_err;
          int kcheckload;
          uint_t pc;
          int maxglobal = -1, maxlocal = -1, maxtlocal = -1;

          kcheckload = cr == NULL ||
              (vstate->dtvs_state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL) == 0;

          dp->dtdo_destructive = 0;

          for (pc = 0; pc < dp->dtdo_len && err == 0; pc++) {
                    dif_instr_t instr = dp->dtdo_buf[pc];

                    uint_t r1 = DIF_INSTR_R1(instr);
                    uint_t r2 = DIF_INSTR_R2(instr);
                    uint_t rd = DIF_INSTR_RD(instr);
                    uint_t rs = DIF_INSTR_RS(instr);
                    uint_t label = DIF_INSTR_LABEL(instr);
                    uint_t v = DIF_INSTR_VAR(instr);
                    uint_t subr = DIF_INSTR_SUBR(instr);
                    uint_t type = DIF_INSTR_TYPE(instr);
                    uint_t op = DIF_INSTR_OP(instr);

                    switch (op) {
                    case DIF_OP_OR:
                    case DIF_OP_XOR:
                    case DIF_OP_AND:
                    case DIF_OP_SLL:
                    case DIF_OP_SRL:
                    case DIF_OP_SRA:
                    case DIF_OP_SUB:
                    case DIF_OP_ADD:
                    case DIF_OP_MUL:
                    case DIF_OP_SDIV:
                    case DIF_OP_UDIV:
                    case DIF_OP_SREM:
                    case DIF_OP_UREM:
                    case DIF_OP_COPYS:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r2);
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_NOT:
                    case DIF_OP_MOV:
                    case DIF_OP_ALLOCS:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_LDSB:
                    case DIF_OP_LDSH:
                    case DIF_OP_LDSW:
                    case DIF_OP_LDUB:
                    case DIF_OP_LDUH:
                    case DIF_OP_LDUW:
                    case DIF_OP_LDX:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              if (kcheckload)
                                        dp->dtdo_buf[pc] = DIF_INSTR_LOAD(op +
                                            DIF_OP_RLDSB - DIF_OP_LDSB, r1, rd);
                              break;
                    case DIF_OP_RLDSB:
                    case DIF_OP_RLDSH:
                    case DIF_OP_RLDSW:
                    case DIF_OP_RLDUB:
                    case DIF_OP_RLDUH:
                    case DIF_OP_RLDUW:
                    case DIF_OP_RLDX:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_ULDSB:
                    case DIF_OP_ULDSH:
                    case DIF_OP_ULDSW:
                    case DIF_OP_ULDUB:
                    case DIF_OP_ULDUH:
                    case DIF_OP_ULDUW:
                    case DIF_OP_ULDX:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_STB:
                    case DIF_OP_STH:
                    case DIF_OP_STW:
                    case DIF_OP_STX:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to 0 address\n");
                              break;
                    case DIF_OP_CMP:
                    case DIF_OP_SCMP:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r2);
                              if (rd != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              break;
                    case DIF_OP_TST:
                              if (r1 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r1);
                              if (r2 != 0 || rd != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              break;
                    case DIF_OP_BA:
                    case DIF_OP_BE:
                    case DIF_OP_BNE:
                    case DIF_OP_BG:
                    case DIF_OP_BGU:
                    case DIF_OP_BGE:
                    case DIF_OP_BGEU:
                    case DIF_OP_BL:
                    case DIF_OP_BLU:
                    case DIF_OP_BLE:
                    case DIF_OP_BLEU:
                              if (label >= dp->dtdo_len) {
                                        err += efunc(pc, "invalid branch target %u\n",
                                            label);
                              }
                              if (label <= pc) {
                                        err += efunc(pc, "backward branch to %u\n",
                                            label);
                              }
                              break;
                    case DIF_OP_RET:
                              if (r1 != 0 || r2 != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              break;
                    case DIF_OP_NOP:
                    case DIF_OP_POPTS:
                    case DIF_OP_FLUSHTS:
                              if (r1 != 0 || r2 != 0 || rd != 0)
                                        err += efunc(pc, "non-zero reserved bits\n");
                              break;
                    case DIF_OP_SETX:
                              if (DIF_INSTR_INTEGER(instr) >= dp->dtdo_intlen) {
                                        err += efunc(pc, "invalid integer ref %u\n",
                                            DIF_INSTR_INTEGER(instr));
                              }
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_SETS:
                              if (DIF_INSTR_STRING(instr) >= dp->dtdo_strlen) {
                                        err += efunc(pc, "invalid string ref %u\n",
                                            DIF_INSTR_STRING(instr));
                              }
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_LDGA:
                    case DIF_OP_LDTA:
                              if (r1 > DIF_VAR_ARRAY_MAX)
                                        err += efunc(pc, "invalid array %u\n", r1);
                              if (r2 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r2);
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_LDGS:
                    case DIF_OP_LDTS:
                    case DIF_OP_LDLS:
                    case DIF_OP_LDGAA:
                    case DIF_OP_LDTAA:
                              if (v < DIF_VAR_OTHER_MIN || v > DIF_VAR_OTHER_MAX)
                                        err += efunc(pc, "invalid variable %u\n", v);
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");
                              break;
                    case DIF_OP_STGS:
                    case DIF_OP_STTS:
                    case DIF_OP_STLS:
                    case DIF_OP_STGAA:
                    case DIF_OP_STTAA:
                              if (v < DIF_VAR_OTHER_UBASE || v > DIF_VAR_OTHER_MAX)
                                        err += efunc(pc, "invalid variable %u\n", v);
                              if (rs >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              break;
                    case DIF_OP_CALL:
                              if (subr > DIF_SUBR_MAX)
                                        err += efunc(pc, "invalid subr %u\n", subr);
                              if (rd >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rd);
                              if (rd == 0)
                                        err += efunc(pc, "cannot write to %r0\n");

                              if (subr == DIF_SUBR_COPYOUT ||
                                  subr == DIF_SUBR_COPYOUTSTR) {
                                        dp->dtdo_destructive = 1;
                              }
                              if (subr == DIF_SUBR_GETF) {
                                        /*
                                         * If we have a getf() we need to record that
                                         * in our state.  Note that our state can be
                                         * NULL if this is a helper -- but in that
                                         * case, the call to getf() is itself illegal,
                                         * and will be caught (slightly later) when
                                         * the helper is validated.
                                         */
                                        if (vstate->dtvs_state != NULL)
                                                  vstate->dtvs_state->dts_getf++;
                              }

                              break;
                    case DIF_OP_PUSHTR:
                              if (type != DIF_TYPE_STRING && type != DIF_TYPE_CTF)
                                        err += efunc(pc, "invalid ref type %u\n", type);
                              if (r2 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r2);
                              if (rs >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rs);
                              break;
                    case DIF_OP_PUSHTV:
                              if (type != DIF_TYPE_CTF)
                                        err += efunc(pc, "invalid val type %u\n", type);
                              if (r2 >= nregs)
                                        err += efunc(pc, "invalid register %u\n", r2);
                              if (rs >= nregs)
                                        err += efunc(pc, "invalid register %u\n", rs);
                              break;
                    default:
                              err += efunc(pc, "invalid opcode %u\n",
                                  DIF_INSTR_OP(instr));
                    }
          }

          if (dp->dtdo_len != 0 &&
              DIF_INSTR_OP(dp->dtdo_buf[dp->dtdo_len - 1]) != DIF_OP_RET) {
                    err += efunc(dp->dtdo_len - 1,
                        "expected 'ret' as last DIF instruction\n");
          }

          if (!(dp->dtdo_rtype.dtdt_flags & (DIF_TF_BYREF | DIF_TF_BYUREF))) {
                    /*
                     * If we're not returning by reference, the size must be either
                     * 0 or the size of one of the base types.
                     */
                    switch (dp->dtdo_rtype.dtdt_size) {
                    case 0:
                    case sizeof (uint8_t):
                    case sizeof (uint16_t):
                    case sizeof (uint32_t):
                    case sizeof (uint64_t):
                              break;

                    default:
                              err += efunc(dp->dtdo_len - 1, "bad return size\n");
                    }
          }

          for (i = 0; i < dp->dtdo_varlen && err == 0; i++) {
                    dtrace_difv_t *v = &dp->dtdo_vartab[i], *existing = NULL;
                    dtrace_diftype_t *vt, *et;
                    uint_t id, ndx;

                    if (v->dtdv_scope != DIFV_SCOPE_GLOBAL &&
                        v->dtdv_scope != DIFV_SCOPE_THREAD &&
                        v->dtdv_scope != DIFV_SCOPE_LOCAL) {
                              err += efunc(i, "unrecognized variable scope %d\n",
                                  v->dtdv_scope);
                              break;
                    }

                    if (v->dtdv_kind != DIFV_KIND_ARRAY &&
                        v->dtdv_kind != DIFV_KIND_SCALAR) {
                              err += efunc(i, "unrecognized variable type %d\n",
                                  v->dtdv_kind);
                              break;
                    }

                    if ((id = v->dtdv_id) > DIF_VARIABLE_MAX) {
                              err += efunc(i, "%d exceeds variable id limit\n", id);
                              break;
                    }

                    if (id < DIF_VAR_OTHER_UBASE)
                              continue;

                    /*
                     * For user-defined variables, we need to check that this
                     * definition is identical to any previous definition that we
                     * encountered.
                     */
                    ndx = id - DIF_VAR_OTHER_UBASE;

                    switch (v->dtdv_scope) {
                    case DIFV_SCOPE_GLOBAL:
                              if (maxglobal == -1 || ndx > maxglobal)
                                        maxglobal = ndx;

                              if (ndx < vstate->dtvs_nglobals) {
                                        dtrace_statvar_t *svar;

                                        if ((svar = vstate->dtvs_globals[ndx]) != NULL)
                                                  existing = &svar->dtsv_var;
                              }

                              break;

                    case DIFV_SCOPE_THREAD:
                              if (maxtlocal == -1 || ndx > maxtlocal)
                                        maxtlocal = ndx;

                              if (ndx < vstate->dtvs_ntlocals)
                                        existing = &vstate->dtvs_tlocals[ndx];
                              break;

                    case DIFV_SCOPE_LOCAL:
                              if (maxlocal == -1 || ndx > maxlocal)
                                        maxlocal = ndx;

                              if (ndx < vstate->dtvs_nlocals) {
                                        dtrace_statvar_t *svar;

                                        if ((svar = vstate->dtvs_locals[ndx]) != NULL)
                                                  existing = &svar->dtsv_var;
                              }

                              break;
                    }

                    vt = &v->dtdv_type;

                    if (vt->dtdt_flags & DIF_TF_BYREF) {
                              if (vt->dtdt_size == 0) {
                                        err += efunc(i, "zero-sized variable\n");
                                        break;
                              }

                              if ((v->dtdv_scope == DIFV_SCOPE_GLOBAL ||
                                  v->dtdv_scope == DIFV_SCOPE_LOCAL) &&
                                  vt->dtdt_size > dtrace_statvar_maxsize) {
                                        err += efunc(i, "oversized by-ref static\n");
                                        break;
                              }
                    }

                    if (existing == NULL || existing->dtdv_id == 0)
                              continue;

                    ASSERT(existing->dtdv_id == v->dtdv_id);
                    ASSERT(existing->dtdv_scope == v->dtdv_scope);

                    if (existing->dtdv_kind != v->dtdv_kind)
                              err += efunc(i, "%d changed variable kind\n", id);

                    et = &existing->dtdv_type;

                    if (vt->dtdt_flags != et->dtdt_flags) {
                              err += efunc(i, "%d changed variable type flags\n", id);
                              break;
                    }

                    if (vt->dtdt_size != 0 && vt->dtdt_size != et->dtdt_size) {
                              err += efunc(i, "%d changed variable type size\n", id);
                              break;
                    }
          }

          for (pc = 0; pc < dp->dtdo_len && err == 0; pc++) {
                    dif_instr_t instr = dp->dtdo_buf[pc];

                    uint_t v = DIF_INSTR_VAR(instr);
                    uint_t op = DIF_INSTR_OP(instr);

                    switch (op) {
                    case DIF_OP_LDGS:
                    case DIF_OP_LDGAA:
                    case DIF_OP_STGS:
                    case DIF_OP_STGAA:
                              if (v > DIF_VAR_OTHER_UBASE + maxglobal)
                                        err += efunc(pc, "invalid variable %u\n", v);
                              break;
                    case DIF_OP_LDTS:
                    case DIF_OP_LDTAA:
                    case DIF_OP_STTS:
                    case DIF_OP_STTAA:
                              if (v > DIF_VAR_OTHER_UBASE + maxtlocal)
                                        err += efunc(pc, "invalid variable %u\n", v);
                              break;
                    case DIF_OP_LDLS:
                    case DIF_OP_STLS:
                              if (v > DIF_VAR_OTHER_UBASE + maxlocal)
                                        err += efunc(pc, "invalid variable %u\n", v);
                              break;
                    default:
                              break;
                    }
          }

          return (err);
}

/*
 * Validate a DTrace DIF object that it is to be used as a helper.  Helpers
 * are much more constrained than normal DIFOs.  Specifically, they may
 * not:
 *
 * 1. Make calls to subroutines other than copyin(), copyinstr() or
 *    miscellaneous string routines
 * 2. Access DTrace variables other than the args[] array, and the
 *    curthread, pid, ppid, tid, execname, zonename, uid and gid variables.
 * 3. Have thread-local variables.
 * 4. Have dynamic variables.
 */
static int
dtrace_difo_validate_helper(dtrace_difo_t *dp)
{
          int (*efunc)(uint_t pc, const char *, ...) = dtrace_difo_err;
          int err = 0;
          uint_t pc;

          for (pc = 0; pc < dp->dtdo_len; pc++) {
                    dif_instr_t instr = dp->dtdo_buf[pc];

                    uint_t v = DIF_INSTR_VAR(instr);
                    uint_t subr = DIF_INSTR_SUBR(instr);
                    uint_t op = DIF_INSTR_OP(instr);

                    switch (op) {
                    case DIF_OP_OR:
                    case DIF_OP_XOR:
                    case DIF_OP_AND:
                    case DIF_OP_SLL:
                    case DIF_OP_SRL:
                    case DIF_OP_SRA:
                    case DIF_OP_SUB:
                    case DIF_OP_ADD:
                    case DIF_OP_MUL:
                    case DIF_OP_SDIV:
                    case DIF_OP_UDIV:
                    case DIF_OP_SREM:
                    case DIF_OP_UREM:
                    case DIF_OP_COPYS:
                    case DIF_OP_NOT:
                    case DIF_OP_MOV:
                    case DIF_OP_RLDSB:
                    case DIF_OP_RLDSH:
                    case DIF_OP_RLDSW:
                    case DIF_OP_RLDUB:
                    case DIF_OP_RLDUH:
                    case DIF_OP_RLDUW:
                    case DIF_OP_RLDX:
                    case DIF_OP_ULDSB:
                    case DIF_OP_ULDSH:
                    case DIF_OP_ULDSW:
                    case DIF_OP_ULDUB:
                    case DIF_OP_ULDUH:
                    case DIF_OP_ULDUW:
                    case DIF_OP_ULDX:
                    case DIF_OP_STB:
                    case DIF_OP_STH:
                    case DIF_OP_STW:
                    case DIF_OP_STX:
                    case DIF_OP_ALLOCS:
                    case DIF_OP_CMP:
                    case DIF_OP_SCMP:
                    case DIF_OP_TST:
                    case DIF_OP_BA:
                    case DIF_OP_BE:
                    case DIF_OP_BNE:
                    case DIF_OP_BG:
                    case DIF_OP_BGU:
                    case DIF_OP_BGE:
                    case DIF_OP_BGEU:
                    case DIF_OP_BL:
                    case DIF_OP_BLU:
                    case DIF_OP_BLE:
                    case DIF_OP_BLEU:
                    case DIF_OP_RET:
                    case DIF_OP_NOP:
                    case DIF_OP_POPTS:
                    case DIF_OP_FLUSHTS:
                    case DIF_OP_SETX:
                    case DIF_OP_SETS:
                    case DIF_OP_LDGA:
                    case DIF_OP_LDLS:
                    case DIF_OP_STGS:
                    case DIF_OP_STLS:
                    case DIF_OP_PUSHTR:
                    case DIF_OP_PUSHTV:
                              break;

                    case DIF_OP_LDGS:
                              if (v >= DIF_VAR_OTHER_UBASE)
                                        break;

                              if (v >= DIF_VAR_ARG0 && v <= DIF_VAR_ARG9)
                                        break;

                              if (v == DIF_VAR_CURTHREAD || v == DIF_VAR_PID ||
                                  v == DIF_VAR_PPID || v == DIF_VAR_TID ||
                                  v == DIF_VAR_EXECARGS ||
                                  v == DIF_VAR_EXECNAME || v == DIF_VAR_ZONENAME ||
                                  v == DIF_VAR_UID || v == DIF_VAR_GID)
                                        break;

                              err += efunc(pc, "illegal variable %u\n", v);
                              break;

                    case DIF_OP_LDTA:
                    case DIF_OP_LDTS:
                    case DIF_OP_LDGAA:
                    case DIF_OP_LDTAA:
                              err += efunc(pc, "illegal dynamic variable load\n");
                              break;

                    case DIF_OP_STTS:
                    case DIF_OP_STGAA:
                    case DIF_OP_STTAA:
                              err += efunc(pc, "illegal dynamic variable store\n");
                              break;

                    case DIF_OP_CALL:
                              if (subr == DIF_SUBR_ALLOCA ||
                                  subr == DIF_SUBR_BCOPY ||
                                  subr == DIF_SUBR_COPYIN ||
                                  subr == DIF_SUBR_COPYINTO ||
                                  subr == DIF_SUBR_COPYINSTR ||
                                  subr == DIF_SUBR_INDEX ||
                                  subr == DIF_SUBR_INET_NTOA ||
                                  subr == DIF_SUBR_INET_NTOA6 ||
                                  subr == DIF_SUBR_INET_NTOP ||
                                  subr == DIF_SUBR_JSON ||
                                  subr == DIF_SUBR_LLTOSTR ||
                                  subr == DIF_SUBR_STRTOLL ||
                                  subr == DIF_SUBR_RINDEX ||
                                  subr == DIF_SUBR_STRCHR ||
                                  subr == DIF_SUBR_STRJOIN ||
                                  subr == DIF_SUBR_STRRCHR ||
                                  subr == DIF_SUBR_STRSTR ||
                                  subr == DIF_SUBR_HTONS ||
                                  subr == DIF_SUBR_HTONL ||
                                  subr == DIF_SUBR_HTONLL ||
                                  subr == DIF_SUBR_NTOHS ||
                                  subr == DIF_SUBR_NTOHL ||
                                  subr == DIF_SUBR_NTOHLL ||
                                  subr == DIF_SUBR_MEMREF)
                                        break;

#if defined(__FreeBSD__) || defined(__NetBSD__)
                              if (subr == DIF_SUBR_MEMSTR)
                                        break;
#endif

                              err += efunc(pc, "invalid subr %u\n", subr);
                              break;

                    default:
                              err += efunc(pc, "invalid opcode %u\n",
                                  DIF_INSTR_OP(instr));
                    }
          }

          return (err);
}

/*
 * Returns 1 if the expression in the DIF object can be cached on a per-thread
 * basis; 0 if not.
 */
static int
dtrace_difo_cacheable(dtrace_difo_t *dp)
{
          int i;

          if (dp == NULL)
                    return (0);

          for (i = 0; i < dp->dtdo_varlen; i++) {
                    dtrace_difv_t *v = &dp->dtdo_vartab[i];

                    if (v->dtdv_scope != DIFV_SCOPE_GLOBAL)
                              continue;

                    switch (v->dtdv_id) {
                    case DIF_VAR_CURTHREAD:
                    case DIF_VAR_PID:
                    case DIF_VAR_TID:
                    case DIF_VAR_EXECARGS:
                    case DIF_VAR_EXECNAME:
                    case DIF_VAR_ZONENAME:
                              break;

                    default:
                              return (0);
                    }
          }

          /*
           * This DIF object may be cacheable.  Now we need to look for any
           * array loading instructions, any memory loading instructions, or
           * any stores to thread-local variables.
           */
          for (i = 0; i < dp->dtdo_len; i++) {
                    uint_t op = DIF_INSTR_OP(dp->dtdo_buf[i]);

                    if ((op >= DIF_OP_LDSB && op <= DIF_OP_LDX) ||
                        (op >= DIF_OP_ULDSB && op <= DIF_OP_ULDX) ||
                        (op >= DIF_OP_RLDSB && op <= DIF_OP_RLDX) ||
                        op == DIF_OP_LDGA || op == DIF_OP_STTS)
                              return (0);
          }

          return (1);
}

static void
dtrace_difo_hold(dtrace_difo_t *dp)
{
          int i;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          dp->dtdo_refcnt++;
          ASSERT(dp->dtdo_refcnt != 0);

          /*
           * We need to check this DIF object for references to the variable
           * DIF_VAR_VTIMESTAMP.
           */
          for (i = 0; i < dp->dtdo_varlen; i++) {
                    dtrace_difv_t *v = &dp->dtdo_vartab[i];

                    if (v->dtdv_id != DIF_VAR_VTIMESTAMP)
                              continue;

                    if (dtrace_vtime_references++ == 0)
                              dtrace_vtime_enable();
          }
}

/*
 * This routine calculates the dynamic variable chunksize for a given DIF
 * object.  The calculation is not fool-proof, and can probably be tricked by
 * malicious DIF -- but it works for all compiler-generated DIF.  Because this
 * calculation is likely imperfect, dtrace_dynvar() is able to gracefully fail
 * if a dynamic variable size exceeds the chunksize.
 */
static void
dtrace_difo_chunksize(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
{
          uint64_t sval = 0;
          dtrace_key_t tupregs[DIF_DTR_NREGS + 2]; /* +2 for thread and id */
          const dif_instr_t *text = dp->dtdo_buf;
          uint_t pc, srd = 0;
          uint_t ttop = 0;
          size_t size, ksize;
          uint_t id, i;

          for (pc = 0; pc < dp->dtdo_len; pc++) {
                    dif_instr_t instr = text[pc];
                    uint_t op = DIF_INSTR_OP(instr);
                    uint_t rd = DIF_INSTR_RD(instr);
                    uint_t r1 = DIF_INSTR_R1(instr);
                    uint_t nkeys = 0;
                    uchar_t scope = 0;

                    dtrace_key_t *key = tupregs;

                    switch (op) {
                    case DIF_OP_SETX:
                              sval = dp->dtdo_inttab[DIF_INSTR_INTEGER(instr)];
                              srd = rd;
                              continue;

                    case DIF_OP_STTS:
                              key = &tupregs[DIF_DTR_NREGS];
                              key[0].dttk_size = 0;
                              key[1].dttk_size = 0;
                              nkeys = 2;
                              scope = DIFV_SCOPE_THREAD;
                              break;

                    case DIF_OP_STGAA:
                    case DIF_OP_STTAA:
                              nkeys = ttop;

                              if (DIF_INSTR_OP(instr) == DIF_OP_STTAA)
                                        key[nkeys++].dttk_size = 0;

                              key[nkeys++].dttk_size = 0;

                              if (op == DIF_OP_STTAA) {
                                        scope = DIFV_SCOPE_THREAD;
                              } else {
                                        scope = DIFV_SCOPE_GLOBAL;
                              }

                              break;

                    case DIF_OP_PUSHTR:
                              if (ttop == DIF_DTR_NREGS)
                                        return;

                              if ((srd == 0 || sval == 0) && r1 == DIF_TYPE_STRING) {
                                        /*
                                         * If the register for the size of the "pushtr"
                                         * is %r0 (or the value is 0) and the type is
                                         * a string, we'll use the system-wide default
                                         * string size.
                                         */
                                        tupregs[ttop++].dttk_size =
                                            dtrace_strsize_default;
                              } else {
                                        if (srd == 0)
                                                  return;

                                        if (sval > LONG_MAX)
                                                  return;

                                        tupregs[ttop++].dttk_size = sval;
                              }

                              break;

                    case DIF_OP_PUSHTV:
                              if (ttop == DIF_DTR_NREGS)
                                        return;

                              tupregs[ttop++].dttk_size = 0;
                              break;

                    case DIF_OP_FLUSHTS:
                              ttop = 0;
                              break;

                    case DIF_OP_POPTS:
                              if (ttop != 0)
                                        ttop--;
                              break;
                    }

                    sval = 0;
                    srd = 0;

                    if (nkeys == 0)
                              continue;

                    /*
                     * We have a dynamic variable allocation; calculate its size.
                     */
                    for (ksize = 0, i = 0; i < nkeys; i++)
                              ksize += P2ROUNDUP(key[i].dttk_size, sizeof (uint64_t));

                    size = sizeof (dtrace_dynvar_t);
                    size += sizeof (dtrace_key_t) * (nkeys - 1);
                    size += ksize;

                    /*
                     * Now we need to determine the size of the stored data.
                     */
                    id = DIF_INSTR_VAR(instr);

                    for (i = 0; i < dp->dtdo_varlen; i++) {
                              dtrace_difv_t *v = &dp->dtdo_vartab[i];

                              if (v->dtdv_id == id && v->dtdv_scope == scope) {
                                        size += v->dtdv_type.dtdt_size;
                                        break;
                              }
                    }

                    if (i == dp->dtdo_varlen)
                              return;

                    /*
                     * We have the size.  If this is larger than the chunk size
                     * for our dynamic variable state, reset the chunk size.
                     */
                    size = P2ROUNDUP(size, sizeof (uint64_t));

                    /*
                     * Before setting the chunk size, check that we're not going
                     * to set it to a negative value...
                     */
                    if (size > LONG_MAX)
                              return;

                    /*
                     * ...and make certain that we didn't badly overflow.
                     */
                    if (size < ksize || size < sizeof (dtrace_dynvar_t))
                              return;

                    if (size > vstate->dtvs_dynvars.dtds_chunksize)
                              vstate->dtvs_dynvars.dtds_chunksize = size;
          }
}

static void
dtrace_difo_init(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
{
          int i, oldsvars, osz, nsz, otlocals, ntlocals;
          uint_t id;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(dp->dtdo_buf != NULL && dp->dtdo_len != 0);

          for (i = 0; i < dp->dtdo_varlen; i++) {
                    dtrace_difv_t *v = &dp->dtdo_vartab[i];
                    dtrace_statvar_t *svar, ***svarp = NULL;
                    size_t dsize = 0;
                    uint8_t scope = v->dtdv_scope;
                    int *np = NULL;

                    if ((id = v->dtdv_id) < DIF_VAR_OTHER_UBASE)
                              continue;

                    id -= DIF_VAR_OTHER_UBASE;

                    switch (scope) {
                    case DIFV_SCOPE_THREAD:
                              while (id >= (otlocals = vstate->dtvs_ntlocals)) {
                                        dtrace_difv_t *tlocals;

                                        if ((ntlocals = (otlocals << 1)) == 0)
                                                  ntlocals = 1;

                                        osz = otlocals * sizeof (dtrace_difv_t);
                                        nsz = ntlocals * sizeof (dtrace_difv_t);

                                        tlocals = kmem_zalloc(nsz, KM_SLEEP);

                                        if (osz != 0) {
                                                  bcopy(vstate->dtvs_tlocals,
                                                      tlocals, osz);
                                                  kmem_free(vstate->dtvs_tlocals, osz);
                                        }

                                        vstate->dtvs_tlocals = tlocals;
                                        vstate->dtvs_ntlocals = ntlocals;
                              }

                              vstate->dtvs_tlocals[id] = *v;
                              continue;

                    case DIFV_SCOPE_LOCAL:
                              np = &vstate->dtvs_nlocals;
                              svarp = &vstate->dtvs_locals;

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF)
                                        dsize = NCPU * (v->dtdv_type.dtdt_size +
                                            sizeof (uint64_t));
                              else
                                        dsize = NCPU * sizeof (uint64_t);

                              break;

                    case DIFV_SCOPE_GLOBAL:
                              np = &vstate->dtvs_nglobals;
                              svarp = &vstate->dtvs_globals;

                              if (v->dtdv_type.dtdt_flags & DIF_TF_BYREF)
                                        dsize = v->dtdv_type.dtdt_size +
                                            sizeof (uint64_t);

                              break;

                    default:
                              ASSERT(0);
                    }

                    while (id >= (oldsvars = *np)) {
                              dtrace_statvar_t **statics;
                              int newsvars, oldsize, newsize;

                              if ((newsvars = (oldsvars << 1)) == 0)
                                        newsvars = 1;

                              oldsize = oldsvars * sizeof (dtrace_statvar_t *);
                              newsize = newsvars * sizeof (dtrace_statvar_t *);

                              statics = kmem_zalloc(newsize, KM_SLEEP);

                              if (oldsize != 0) {
                                        bcopy(*svarp, statics, oldsize);
                                        kmem_free(*svarp, oldsize);
                              }

                              *svarp = statics;
                              *np = newsvars;
                    }

                    if ((svar = (*svarp)[id]) == NULL) {
                              svar = kmem_zalloc(sizeof (dtrace_statvar_t), KM_SLEEP);
                              svar->dtsv_var = *v;

                              if ((svar->dtsv_size = dsize) != 0) {
                                        svar->dtsv_data = (uint64_t)(uintptr_t)
                                            kmem_zalloc(dsize, KM_SLEEP);
                              }

                              (*svarp)[id] = svar;
                    }

                    svar->dtsv_refcnt++;
          }

          dtrace_difo_chunksize(dp, vstate);
          dtrace_difo_hold(dp);
}

static dtrace_difo_t *
dtrace_difo_duplicate(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
{
          dtrace_difo_t *new;
          size_t sz;

          ASSERT(dp->dtdo_buf != NULL);
          ASSERT(dp->dtdo_refcnt != 0);

          new = kmem_zalloc(sizeof (dtrace_difo_t), KM_SLEEP);

          ASSERT(dp->dtdo_buf != NULL);
          sz = dp->dtdo_len * sizeof (dif_instr_t);
          new->dtdo_buf = kmem_alloc(sz, KM_SLEEP);
          bcopy(dp->dtdo_buf, new->dtdo_buf, sz);
          new->dtdo_len = dp->dtdo_len;

          if (dp->dtdo_strtab != NULL) {
                    ASSERT(dp->dtdo_strlen != 0);
                    new->dtdo_strtab = kmem_alloc(dp->dtdo_strlen, KM_SLEEP);
                    bcopy(dp->dtdo_strtab, new->dtdo_strtab, dp->dtdo_strlen);
                    new->dtdo_strlen = dp->dtdo_strlen;
          }

          if (dp->dtdo_inttab != NULL) {
                    ASSERT(dp->dtdo_intlen != 0);
                    sz = dp->dtdo_intlen * sizeof (uint64_t);
                    new->dtdo_inttab = kmem_alloc(sz, KM_SLEEP);
                    bcopy(dp->dtdo_inttab, new->dtdo_inttab, sz);
                    new->dtdo_intlen = dp->dtdo_intlen;
          }

          if (dp->dtdo_vartab != NULL) {
                    ASSERT(dp->dtdo_varlen != 0);
                    sz = dp->dtdo_varlen * sizeof (dtrace_difv_t);
                    new->dtdo_vartab = kmem_alloc(sz, KM_SLEEP);
                    bcopy(dp->dtdo_vartab, new->dtdo_vartab, sz);
                    new->dtdo_varlen = dp->dtdo_varlen;
          }

          dtrace_difo_init(new, vstate);
          return (new);
}

static void
dtrace_difo_destroy(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
{
          int i;

          ASSERT(dp->dtdo_refcnt == 0);

          for (i = 0; i < dp->dtdo_varlen; i++) {
                    dtrace_difv_t *v = &dp->dtdo_vartab[i];
                    dtrace_statvar_t *svar, **svarp = NULL;
                    uint_t id;
                    uint8_t scope = v->dtdv_scope;
                    int *np = NULL;

                    switch (scope) {
                    case DIFV_SCOPE_THREAD:
                              continue;

                    case DIFV_SCOPE_LOCAL:
                              np = &vstate->dtvs_nlocals;
                              svarp = vstate->dtvs_locals;
                              break;

                    case DIFV_SCOPE_GLOBAL:
                              np = &vstate->dtvs_nglobals;
                              svarp = vstate->dtvs_globals;
                              break;

                    default:
                              ASSERT(0);
                    }

                    if ((id = v->dtdv_id) < DIF_VAR_OTHER_UBASE)
                              continue;

                    id -= DIF_VAR_OTHER_UBASE;
                    ASSERT(id < *np);

                    svar = svarp[id];
                    ASSERT(svar != NULL);
                    ASSERT(svar->dtsv_refcnt > 0);

                    if (--svar->dtsv_refcnt > 0)
                              continue;

                    if (svar->dtsv_size != 0) {
                              ASSERT(svar->dtsv_data != 0);
                              kmem_free((void *)(uintptr_t)svar->dtsv_data,
                                  svar->dtsv_size);
                    }

                    kmem_free(svar, sizeof (dtrace_statvar_t));
                    svarp[id] = NULL;
          }

          if (dp->dtdo_buf != NULL)
                    kmem_free(dp->dtdo_buf, dp->dtdo_len * sizeof (dif_instr_t));
          if (dp->dtdo_inttab != NULL)
                    kmem_free(dp->dtdo_inttab, dp->dtdo_intlen * sizeof (uint64_t));
          if (dp->dtdo_strtab != NULL)
                    kmem_free(dp->dtdo_strtab, dp->dtdo_strlen);
          if (dp->dtdo_vartab != NULL)
                    kmem_free(dp->dtdo_vartab, dp->dtdo_varlen * sizeof (dtrace_difv_t));

          kmem_free(dp, sizeof (dtrace_difo_t));
}

static void
dtrace_difo_release(dtrace_difo_t *dp, dtrace_vstate_t *vstate)
{
          int i;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(dp->dtdo_refcnt != 0);

          for (i = 0; i < dp->dtdo_varlen; i++) {
                    dtrace_difv_t *v = &dp->dtdo_vartab[i];

                    if (v->dtdv_id != DIF_VAR_VTIMESTAMP)
                              continue;

                    ASSERT(dtrace_vtime_references > 0);
                    if (--dtrace_vtime_references == 0)
                              dtrace_vtime_disable();
          }

          if (--dp->dtdo_refcnt == 0)
                    dtrace_difo_destroy(dp, vstate);
}

/*
 * DTrace Format Functions
 */
static uint16_t
dtrace_format_add(dtrace_state_t *state, char *str)
{
          char *fmt, **new;
          uint16_t ndx, len = strlen(str) + 1;

          fmt = kmem_zalloc(len, KM_SLEEP);
          bcopy(str, fmt, len);

          for (ndx = 0; ndx < state->dts_nformats; ndx++) {
                    if (state->dts_formats[ndx] == NULL) {
                              state->dts_formats[ndx] = fmt;
                              return (ndx + 1);
                    }
          }

          if (state->dts_nformats == USHRT_MAX) {
                    /*
                     * This is only likely if a denial-of-service attack is being
                     * attempted.  As such, it's okay to fail silently here.
                     */
                    kmem_free(fmt, len);
                    return (0);
          }

          /*
           * For simplicity, we always resize the formats array to be exactly the
           * number of formats.
           */
          ndx = state->dts_nformats++;
          new = kmem_alloc((ndx + 1) * sizeof (char *), KM_SLEEP);

          if (state->dts_formats != NULL) {
                    ASSERT(ndx != 0);
                    bcopy(state->dts_formats, new, ndx * sizeof (char *));
                    kmem_free(state->dts_formats, ndx * sizeof (char *));
          }

          state->dts_formats = new;
          state->dts_formats[ndx] = fmt;

          return (ndx + 1);
}

static void
dtrace_format_remove(dtrace_state_t *state, uint16_t format)
{
          char *fmt;

          ASSERT(state->dts_formats != NULL);
          ASSERT(format <= state->dts_nformats);
          ASSERT(state->dts_formats[format - 1] != NULL);

          fmt = state->dts_formats[format - 1];
          kmem_free(fmt, strlen(fmt) + 1);
          state->dts_formats[format - 1] = NULL;
}

static void
dtrace_format_destroy(dtrace_state_t *state)
{
          int i;

          if (state->dts_nformats == 0) {
                    ASSERT(state->dts_formats == NULL);
                    return;
          }

          ASSERT(state->dts_formats != NULL);

          for (i = 0; i < state->dts_nformats; i++) {
                    char *fmt = state->dts_formats[i];

                    if (fmt == NULL)
                              continue;

                    kmem_free(fmt, strlen(fmt) + 1);
          }

          kmem_free(state->dts_formats, state->dts_nformats * sizeof (char *));
          state->dts_nformats = 0;
          state->dts_formats = NULL;
}

/*
 * DTrace Predicate Functions
 */
static dtrace_predicate_t *
dtrace_predicate_create(dtrace_difo_t *dp)
{
          dtrace_predicate_t *pred;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(dp->dtdo_refcnt != 0);

          pred = kmem_zalloc(sizeof (dtrace_predicate_t), KM_SLEEP);
          pred->dtp_difo = dp;
          pred->dtp_refcnt = 1;

          if (!dtrace_difo_cacheable(dp))
                    return (pred);

          if (dtrace_predcache_id == DTRACE_CACHEIDNONE) {
                    /*
                     * This is only theoretically possible -- we have had 2^32
                     * cacheable predicates on this machine.  We cannot allow any
                     * more predicates to become cacheable:  as unlikely as it is,
                     * there may be a thread caching a (now stale) predicate cache
                     * ID. (N.B.: the temptation is being successfully resisted to
                     * have this cmn_err() "Holy shit -- we executed this code!")
                     */
                    return (pred);
          }

          pred->dtp_cacheid = dtrace_predcache_id++;

          return (pred);
}

static void
dtrace_predicate_hold(dtrace_predicate_t *pred)
{
          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(pred->dtp_difo != NULL && pred->dtp_difo->dtdo_refcnt != 0);
          ASSERT(pred->dtp_refcnt > 0);

          pred->dtp_refcnt++;
}

static void
dtrace_predicate_release(dtrace_predicate_t *pred, dtrace_vstate_t *vstate)
{
          dtrace_difo_t *dp = pred->dtp_difo;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(dp != NULL && dp->dtdo_refcnt != 0);
          ASSERT(pred->dtp_refcnt > 0);

          if (--pred->dtp_refcnt == 0) {
                    dtrace_difo_release(pred->dtp_difo, vstate);
                    kmem_free(pred, sizeof (dtrace_predicate_t));
          }
}

/*
 * DTrace Action Description Functions
 */
static dtrace_actdesc_t *
dtrace_actdesc_create(dtrace_actkind_t kind, uint32_t ntuple,
    uint64_t uarg, uint64_t arg)
{
          dtrace_actdesc_t *act;

#ifdef illumos
          ASSERT(!DTRACEACT_ISPRINTFLIKE(kind) || (arg != NULL &&
              arg >= KERNELBASE) || (arg == NULL && kind == DTRACEACT_PRINTA));
#endif

          act = kmem_zalloc(sizeof (dtrace_actdesc_t), KM_SLEEP);
          act->dtad_kind = kind;
          act->dtad_ntuple = ntuple;
          act->dtad_uarg = uarg;
          act->dtad_arg = arg;
          act->dtad_refcnt = 1;

          return (act);
}

static void
dtrace_actdesc_hold(dtrace_actdesc_t *act)
{
          ASSERT(act->dtad_refcnt >= 1);
          act->dtad_refcnt++;
}

static void
dtrace_actdesc_release(dtrace_actdesc_t *act, dtrace_vstate_t *vstate)
{
          dtrace_actkind_t kind = act->dtad_kind;
          dtrace_difo_t *dp;

          ASSERT(act->dtad_refcnt >= 1);

          if (--act->dtad_refcnt != 0)
                    return;

          if ((dp = act->dtad_difo) != NULL)
                    dtrace_difo_release(dp, vstate);

          if (DTRACEACT_ISPRINTFLIKE(kind)) {
                    char *str = (char *)(uintptr_t)act->dtad_arg;

#ifdef illumos
                    ASSERT((str != NULL && (uintptr_t)str >= KERNELBASE) ||
                        (str == NULL && act->dtad_kind == DTRACEACT_PRINTA));
#endif

                    if (str != NULL)
                              kmem_free(str, strlen(str) + 1);
          }

          kmem_free(act, sizeof (dtrace_actdesc_t));
}

/*
 * DTrace ECB Functions
 */
static dtrace_ecb_t *
dtrace_ecb_add(dtrace_state_t *state, dtrace_probe_t *probe)
{
          dtrace_ecb_t *ecb;
          dtrace_epid_t epid;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          ecb = kmem_zalloc(sizeof (dtrace_ecb_t), KM_SLEEP);
          ecb->dte_predicate = NULL;
          ecb->dte_probe = probe;

          /*
           * The default size is the size of the default action: recording
           * the header.
           */
          ecb->dte_size = ecb->dte_needed = sizeof (dtrace_rechdr_t);
          ecb->dte_alignment = sizeof (dtrace_epid_t);

          epid = state->dts_epid++;

          if (epid - 1 >= state->dts_necbs) {
                    dtrace_ecb_t **oecbs = state->dts_ecbs, **ecbs;
                    int necbs = state->dts_necbs << 1;

                    ASSERT(epid == state->dts_necbs + 1);

                    if (necbs == 0) {
                              ASSERT(oecbs == NULL);
                              necbs = 1;
                    }

                    ecbs = kmem_zalloc(necbs * sizeof (*ecbs), KM_SLEEP);

                    if (oecbs != NULL)
                              bcopy(oecbs, ecbs, state->dts_necbs * sizeof (*ecbs));

                    dtrace_membar_producer();
                    state->dts_ecbs = ecbs;

                    if (oecbs != NULL) {
                              /*
                               * If this state is active, we must dtrace_sync()
                               * before we can free the old dts_ecbs array:  we're
                               * coming in hot, and there may be active ring
                               * buffer processing (which indexes into the dts_ecbs
                               * array) on another CPU.
                               */
                              if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE)
                                        dtrace_sync();

                              kmem_free(oecbs, state->dts_necbs * sizeof (*ecbs));
                    }

                    dtrace_membar_producer();
                    state->dts_necbs = necbs;
          }

          ecb->dte_state = state;

          ASSERT(state->dts_ecbs[epid - 1] == NULL);
          dtrace_membar_producer();
          state->dts_ecbs[(ecb->dte_epid = epid) - 1] = ecb;

          return (ecb);
}

static int
dtrace_ecb_enable(dtrace_ecb_t *ecb)
{
          dtrace_probe_t *probe = ecb->dte_probe;

          ASSERT(MUTEX_HELD(&cpu_lock));
          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(ecb->dte_next == NULL);

          if (probe == NULL) {
                    /*
                     * This is the NULL probe -- there's nothing to do.
                     */
                    return (0);
          }

          if (probe->dtpr_ecb == NULL) {
                    dtrace_provider_t *prov = probe->dtpr_provider;

                    /*
                     * We're the first ECB on this probe.
                     */
                    probe->dtpr_ecb = probe->dtpr_ecb_last = ecb;

                    if (ecb->dte_predicate != NULL)
                              probe->dtpr_predcache = ecb->dte_predicate->dtp_cacheid;

                    return (prov->dtpv_pops.dtps_enable(prov->dtpv_arg,
                        probe->dtpr_id, probe->dtpr_arg));
          } else {
                    /*
                     * This probe is already active.  Swing the last pointer to
                     * point to the new ECB, and issue a dtrace_sync() to assure
                     * that all CPUs have seen the change.
                     */
                    ASSERT(probe->dtpr_ecb_last != NULL);
                    probe->dtpr_ecb_last->dte_next = ecb;
                    probe->dtpr_ecb_last = ecb;
                    probe->dtpr_predcache = 0;

                    dtrace_sync();
                    return (0);
          }
}

static int
dtrace_ecb_resize(dtrace_ecb_t *ecb)
{
          dtrace_action_t *act;
          uint32_t curneeded = UINT32_MAX;
          uint32_t aggbase = UINT32_MAX;

          /*
           * If we record anything, we always record the dtrace_rechdr_t.  (And
           * we always record it first.)
           */
          ecb->dte_size = sizeof (dtrace_rechdr_t);
          ecb->dte_alignment = sizeof (dtrace_epid_t);

          for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                    dtrace_recdesc_t *rec = &act->dta_rec;
                    ASSERT(rec->dtrd_size > 0 || rec->dtrd_alignment == 1);

                    ecb->dte_alignment = MAX(ecb->dte_alignment,
                        rec->dtrd_alignment);

                    if (DTRACEACT_ISAGG(act->dta_kind)) {
                              dtrace_aggregation_t *agg = (dtrace_aggregation_t *)act;

                              ASSERT(rec->dtrd_size != 0);
                              ASSERT(agg->dtag_first != NULL);
                              ASSERT(act->dta_prev->dta_intuple);
                              ASSERT(aggbase != UINT32_MAX);
                              ASSERT(curneeded != UINT32_MAX);

                              agg->dtag_base = aggbase;

                              curneeded = P2ROUNDUP(curneeded, rec->dtrd_alignment);
                              rec->dtrd_offset = curneeded;
                              if (curneeded + rec->dtrd_size < curneeded)
                                        return (EINVAL);
                              curneeded += rec->dtrd_size;
                              ecb->dte_needed = MAX(ecb->dte_needed, curneeded);

                              aggbase = UINT32_MAX;
                              curneeded = UINT32_MAX;
                    } else if (act->dta_intuple) {
                              if (curneeded == UINT32_MAX) {
                                        /*
                                         * This is the first record in a tuple.  Align
                                         * curneeded to be at offset 4 in an 8-byte
                                         * aligned block.
                                         */
                                        ASSERT(act->dta_prev == NULL ||
                                            !act->dta_prev->dta_intuple);
                                        ASSERT3U(aggbase, ==, UINT32_MAX);
                                        curneeded = P2PHASEUP(ecb->dte_size,
                                            sizeof (uint64_t), sizeof (dtrace_aggid_t));

                                        aggbase = curneeded - sizeof (dtrace_aggid_t);
                                        ASSERT(IS_P2ALIGNED(aggbase,
                                            sizeof (uint64_t)));
                              }
                              curneeded = P2ROUNDUP(curneeded, rec->dtrd_alignment);
                              rec->dtrd_offset = curneeded;
                              if (curneeded + rec->dtrd_size < curneeded)
                                        return (EINVAL);
                              curneeded += rec->dtrd_size;
                    } else {
                              /* tuples must be followed by an aggregation */
                              ASSERT(act->dta_prev == NULL ||
                                  !act->dta_prev->dta_intuple);

                              ecb->dte_size = P2ROUNDUP(ecb->dte_size,
                                  rec->dtrd_alignment);
                              rec->dtrd_offset = ecb->dte_size;
                              if (ecb->dte_size + rec->dtrd_size < ecb->dte_size)
                                        return (EINVAL);
                              ecb->dte_size += rec->dtrd_size;
                              ecb->dte_needed = MAX(ecb->dte_needed, ecb->dte_size);
                    }
          }

          if ((act = ecb->dte_action) != NULL &&
              !(act->dta_kind == DTRACEACT_SPECULATE && act->dta_next == NULL) &&
              ecb->dte_size == sizeof (dtrace_rechdr_t)) {
                    /*
                     * If the size is still sizeof (dtrace_rechdr_t), then all
                     * actions store no data; set the size to 0.
                     */
                    ecb->dte_size = 0;
          }

          ecb->dte_size = P2ROUNDUP(ecb->dte_size, sizeof (dtrace_epid_t));
          ecb->dte_needed = P2ROUNDUP(ecb->dte_needed, (sizeof (dtrace_epid_t)));
          ecb->dte_state->dts_needed = MAX(ecb->dte_state->dts_needed,
              ecb->dte_needed);
          return (0);
}

static dtrace_action_t *
dtrace_ecb_aggregation_create(dtrace_ecb_t *ecb, dtrace_actdesc_t *desc)
{
          dtrace_aggregation_t *agg;
          size_t size = sizeof (uint64_t);
          int ntuple = desc->dtad_ntuple;
          dtrace_action_t *act;
          dtrace_recdesc_t *frec;
          dtrace_aggid_t aggid;
          dtrace_state_t *state = ecb->dte_state;

          agg = kmem_zalloc(sizeof (dtrace_aggregation_t), KM_SLEEP);
          agg->dtag_ecb = ecb;

          ASSERT(DTRACEACT_ISAGG(desc->dtad_kind));

          switch (desc->dtad_kind) {
          case DTRACEAGG_MIN:
                    agg->dtag_initial = INT64_MAX;
                    agg->dtag_aggregate = dtrace_aggregate_min;
                    break;

          case DTRACEAGG_MAX:
                    agg->dtag_initial = INT64_MIN;
                    agg->dtag_aggregate = dtrace_aggregate_max;
                    break;

          case DTRACEAGG_COUNT:
                    agg->dtag_aggregate = dtrace_aggregate_count;
                    break;

          case DTRACEAGG_QUANTIZE:
                    agg->dtag_aggregate = dtrace_aggregate_quantize;
                    size = (((sizeof (uint64_t) * NBBY) - 1) * 2 + 1) *
                        sizeof (uint64_t);
                    break;

          case DTRACEAGG_LQUANTIZE: {
                    uint16_t step = DTRACE_LQUANTIZE_STEP(desc->dtad_arg);
                    uint16_t levels = DTRACE_LQUANTIZE_LEVELS(desc->dtad_arg);

                    agg->dtag_initial = desc->dtad_arg;
                    agg->dtag_aggregate = dtrace_aggregate_lquantize;

                    if (step == 0 || levels == 0)
                              goto err;

                    size = levels * sizeof (uint64_t) + 3 * sizeof (uint64_t);
                    break;
          }

          case DTRACEAGG_LLQUANTIZE: {
                    uint16_t factor = DTRACE_LLQUANTIZE_FACTOR(desc->dtad_arg);
                    uint16_t low = DTRACE_LLQUANTIZE_LOW(desc->dtad_arg);
                    uint16_t high = DTRACE_LLQUANTIZE_HIGH(desc->dtad_arg);
                    uint16_t nsteps = DTRACE_LLQUANTIZE_NSTEP(desc->dtad_arg);
                    int64_t v;

                    agg->dtag_initial = desc->dtad_arg;
                    agg->dtag_aggregate = dtrace_aggregate_llquantize;

                    if (factor < 2 || low >= high || nsteps < factor)
                              goto err;

                    /*
                     * Now check that the number of steps evenly divides a power
                     * of the factor.  (This assures both integer bucket size and
                     * linearity within each magnitude.)
                     */
                    for (v = factor; v < nsteps; v *= factor)
                              continue;

                    if ((v % nsteps) || (nsteps % factor))
                              goto err;

                    size = (dtrace_aggregate_llquantize_bucket(factor,
                        low, high, nsteps, INT64_MAX) + 2) * sizeof (uint64_t);
                    break;
          }

          case DTRACEAGG_AVG:
                    agg->dtag_aggregate = dtrace_aggregate_avg;
                    size = sizeof (uint64_t) * 2;
                    break;

          case DTRACEAGG_STDDEV:
                    agg->dtag_aggregate = dtrace_aggregate_stddev;
                    size = sizeof (uint64_t) * 4;
                    break;

          case DTRACEAGG_SUM:
                    agg->dtag_aggregate = dtrace_aggregate_sum;
                    break;

          default:
                    goto err;
          }

          agg->dtag_action.dta_rec.dtrd_size = size;

          if (ntuple == 0)
                    goto err;

          /*
           * We must make sure that we have enough actions for the n-tuple.
           */
          for (act = ecb->dte_action_last; act != NULL; act = act->dta_prev) {
                    if (DTRACEACT_ISAGG(act->dta_kind))
                              break;

                    if (--ntuple == 0) {
                              /*
                               * This is the action with which our n-tuple begins.
                               */
                              agg->dtag_first = act;
                              goto success;
                    }
          }

          /*
           * This n-tuple is short by ntuple elements.  Return failure.
           */
          ASSERT(ntuple != 0);
err:
          kmem_free(agg, sizeof (dtrace_aggregation_t));
          return (NULL);

success:
          /*
           * If the last action in the tuple has a size of zero, it's actually
           * an expression argument for the aggregating action.
           */
          ASSERT(ecb->dte_action_last != NULL);
          act = ecb->dte_action_last;

          if (act->dta_kind == DTRACEACT_DIFEXPR) {
                    ASSERT(act->dta_difo != NULL);

                    if (act->dta_difo->dtdo_rtype.dtdt_size == 0)
                              agg->dtag_hasarg = 1;
          }

          /*
           * We need to allocate an id for this aggregation.
           */

#ifdef illumos
          aggid = (dtrace_aggid_t)(uintptr_t)vmem_alloc(state->dts_aggid_arena, 1,
              VM_BESTFIT | VM_SLEEP);
#endif
#ifdef __FreeBSD__
          aggid = alloc_unr(state->dts_aggid_arena);
#endif
#ifdef __NetBSD__
          vmem_addr_t offset;

          if (vmem_alloc(state->dts_aggid_arena, 1, VM_BESTFIT | VM_SLEEP,
              &offset) != 0)
                    ASSERT(0);
          aggid = (dtrace_aggid_t)(uintptr_t)offset;
#endif

          if (aggid - 1 >= state->dts_naggregations) {
                    dtrace_aggregation_t **oaggs = state->dts_aggregations;
                    dtrace_aggregation_t **aggs;
                    int naggs = state->dts_naggregations << 1;
                    int onaggs = state->dts_naggregations;

                    ASSERT(aggid == state->dts_naggregations + 1);

                    if (naggs == 0) {
                              ASSERT(oaggs == NULL);
                              naggs = 1;
                    }

                    aggs = kmem_zalloc(naggs * sizeof (*aggs), KM_SLEEP);

                    if (oaggs != NULL) {
                              bcopy(oaggs, aggs, onaggs * sizeof (*aggs));
                              kmem_free(oaggs, onaggs * sizeof (*aggs));
                    }

                    state->dts_aggregations = aggs;
                    state->dts_naggregations = naggs;
          }

          ASSERT(state->dts_aggregations[aggid - 1] == NULL);
          state->dts_aggregations[(agg->dtag_id = aggid) - 1] = agg;

          frec = &agg->dtag_first->dta_rec;
          if (frec->dtrd_alignment < sizeof (dtrace_aggid_t))
                    frec->dtrd_alignment = sizeof (dtrace_aggid_t);

          for (act = agg->dtag_first; act != NULL; act = act->dta_next) {
                    ASSERT(!act->dta_intuple);
                    act->dta_intuple = 1;
          }

          return (&agg->dtag_action);
}

static void
dtrace_ecb_aggregation_destroy(dtrace_ecb_t *ecb, dtrace_action_t *act)
{
          dtrace_aggregation_t *agg = (dtrace_aggregation_t *)act;
          dtrace_state_t *state = ecb->dte_state;
          dtrace_aggid_t aggid = agg->dtag_id;

          ASSERT(DTRACEACT_ISAGG(act->dta_kind));
#ifdef illumos
          vmem_free(state->dts_aggid_arena, (void *)(uintptr_t)aggid, 1);
#endif
#ifdef __FreeBSD__
          free_unr(state->dts_aggid_arena, aggid);
#endif
#ifdef __NetBSD__
          vmem_free(state->dts_aggid_arena, (uintptr_t)aggid, 1);
#endif

          ASSERT(state->dts_aggregations[aggid - 1] == agg);
          state->dts_aggregations[aggid - 1] = NULL;

          kmem_free(agg, sizeof (dtrace_aggregation_t));
}

static int
dtrace_ecb_action_add(dtrace_ecb_t *ecb, dtrace_actdesc_t *desc)
{
          dtrace_action_t *action, *last;
          dtrace_difo_t *dp = desc->dtad_difo;
          uint32_t size = 0, align = sizeof (uint8_t), mask;
          uint16_t format = 0;
          dtrace_recdesc_t *rec;
          dtrace_state_t *state = ecb->dte_state;
          dtrace_optval_t *opt = state->dts_options, nframes = 0, strsize;
          uint64_t arg = desc->dtad_arg;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(ecb->dte_action == NULL || ecb->dte_action->dta_refcnt == 1);

          if (DTRACEACT_ISAGG(desc->dtad_kind)) {
                    /*
                     * If this is an aggregating action, there must be neither
                     * a speculate nor a commit on the action chain.
                     */
                    dtrace_action_t *act;

                    for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                              if (act->dta_kind == DTRACEACT_COMMIT)
                                        return (EINVAL);

                              if (act->dta_kind == DTRACEACT_SPECULATE)
                                        return (EINVAL);
                    }

                    action = dtrace_ecb_aggregation_create(ecb, desc);

                    if (action == NULL)
                              return (EINVAL);
          } else {
                    if (DTRACEACT_ISDESTRUCTIVE(desc->dtad_kind) ||
                        (desc->dtad_kind == DTRACEACT_DIFEXPR &&
                        dp != NULL && dp->dtdo_destructive)) {
                              state->dts_destructive = 1;
                    }

                    switch (desc->dtad_kind) {
                    case DTRACEACT_PRINTF:
                    case DTRACEACT_PRINTA:
                    case DTRACEACT_SYSTEM:
                    case DTRACEACT_FREOPEN:
                    case DTRACEACT_DIFEXPR:
                              /*
                               * We know that our arg is a string -- turn it into a
                               * format.
                               */
                              if (arg == 0) {
                                        ASSERT(desc->dtad_kind == DTRACEACT_PRINTA ||
                                            desc->dtad_kind == DTRACEACT_DIFEXPR);
                                        format = 0;
                              } else {
                                        ASSERT(arg != 0);
#ifdef illumos
                                        ASSERT(arg > KERNELBASE);
#endif
                                        format = dtrace_format_add(state,
                                            (char *)(uintptr_t)arg);
                              }

                              /*FALLTHROUGH*/
                    case DTRACEACT_LIBACT:
                    case DTRACEACT_TRACEMEM:
                    case DTRACEACT_TRACEMEM_DYNSIZE:
                              if (dp == NULL)
                                        return (EINVAL);

                              if ((size = dp->dtdo_rtype.dtdt_size) != 0)
                                        break;

                              if (dp->dtdo_rtype.dtdt_kind == DIF_TYPE_STRING) {
                                        if (!(dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                                  return (EINVAL);

                                        size = opt[DTRACEOPT_STRSIZE];
                              }

                              break;

                    case DTRACEACT_STACK:
                              if ((nframes = arg) == 0) {
                                        nframes = opt[DTRACEOPT_STACKFRAMES];
                                        ASSERT(nframes > 0);
                                        arg = nframes;
                              }

                              size = nframes * sizeof (pc_t);
                              break;

                    case DTRACEACT_JSTACK:
                              if ((strsize = DTRACE_USTACK_STRSIZE(arg)) == 0)
                                        strsize = opt[DTRACEOPT_JSTACKSTRSIZE];

                              if ((nframes = DTRACE_USTACK_NFRAMES(arg)) == 0)
                                        nframes = opt[DTRACEOPT_JSTACKFRAMES];

                              arg = DTRACE_USTACK_ARG(nframes, strsize);

                              /*FALLTHROUGH*/
                    case DTRACEACT_USTACK:
                              if (desc->dtad_kind != DTRACEACT_JSTACK &&
                                  (nframes = DTRACE_USTACK_NFRAMES(arg)) == 0) {
                                        strsize = DTRACE_USTACK_STRSIZE(arg);
                                        nframes = opt[DTRACEOPT_USTACKFRAMES];
                                        ASSERT(nframes > 0);
                                        arg = DTRACE_USTACK_ARG(nframes, strsize);
                              }

                              /*
                               * Save a slot for the pid.
                               */
                              size = (nframes + 1) * sizeof (uint64_t);
                              size += DTRACE_USTACK_STRSIZE(arg);
                              size = P2ROUNDUP(size, (uint32_t)(sizeof (uintptr_t)));

                              break;

                    case DTRACEACT_SYM:
                    case DTRACEACT_MOD:
                              if (dp == NULL || ((size = dp->dtdo_rtype.dtdt_size) !=
                                  sizeof (uint64_t)) ||
                                  (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                        return (EINVAL);
                              break;

                    case DTRACEACT_USYM:
                    case DTRACEACT_UMOD:
                    case DTRACEACT_UADDR:
                              if (dp == NULL ||
                                  (dp->dtdo_rtype.dtdt_size != sizeof (uint64_t)) ||
                                  (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                        return (EINVAL);

                              /*
                               * We have a slot for the pid, plus a slot for the
                               * argument.  To keep things simple (aligned with
                               * bitness-neutral sizing), we store each as a 64-bit
                               * quantity.
                               */
                              size = 2 * sizeof (uint64_t);
                              break;

                    case DTRACEACT_STOP:
                    case DTRACEACT_BREAKPOINT:
                    case DTRACEACT_PANIC:
                              break;

                    case DTRACEACT_CHILL:
                    case DTRACEACT_DISCARD:
                    case DTRACEACT_RAISE:
                              if (dp == NULL)
                                        return (EINVAL);
                              break;

                    case DTRACEACT_EXIT:
                              if (dp == NULL ||
                                  (size = dp->dtdo_rtype.dtdt_size) != sizeof (int) ||
                                  (dp->dtdo_rtype.dtdt_flags & DIF_TF_BYREF))
                                        return (EINVAL);
                              break;

                    case DTRACEACT_SPECULATE:
                              if (ecb->dte_size > sizeof (dtrace_rechdr_t))
                                        return (EINVAL);

                              if (dp == NULL)
                                        return (EINVAL);

                              state->dts_speculates = 1;
                              break;

                    case DTRACEACT_PRINTM:
                              size = dp->dtdo_rtype.dtdt_size;
                              break;

                    case DTRACEACT_COMMIT: {
                              dtrace_action_t *act = ecb->dte_action;

                              for (; act != NULL; act = act->dta_next) {
                                        if (act->dta_kind == DTRACEACT_COMMIT)
                                                  return (EINVAL);
                              }

                              if (dp == NULL)
                                        return (EINVAL);
                              break;
                    }

                    default:
                              return (EINVAL);
                    }

                    if (size != 0 || desc->dtad_kind == DTRACEACT_SPECULATE) {
                              /*
                               * If this is a data-storing action or a speculate,
                               * we must be sure that there isn't a commit on the
                               * action chain.
                               */
                              dtrace_action_t *act = ecb->dte_action;

                              for (; act != NULL; act = act->dta_next) {
                                        if (act->dta_kind == DTRACEACT_COMMIT)
                                                  return (EINVAL);
                              }
                    }

                    action = kmem_zalloc(sizeof (dtrace_action_t), KM_SLEEP);
                    action->dta_rec.dtrd_size = size;
          }

          action->dta_refcnt = 1;
          rec = &action->dta_rec;
          size = rec->dtrd_size;

          for (mask = sizeof (uint64_t) - 1; size != 0 && mask > 0; mask >>= 1) {
                    if (!(size & mask)) {
                              align = mask + 1;
                              break;
                    }
          }

          action->dta_kind = desc->dtad_kind;

          if ((action->dta_difo = dp) != NULL)
                    dtrace_difo_hold(dp);

          rec->dtrd_action = action->dta_kind;
          rec->dtrd_arg = arg;
          rec->dtrd_uarg = desc->dtad_uarg;
          rec->dtrd_alignment = (uint16_t)align;
          rec->dtrd_format = format;

          if ((last = ecb->dte_action_last) != NULL) {
                    ASSERT(ecb->dte_action != NULL);
                    action->dta_prev = last;
                    last->dta_next = action;
          } else {
                    ASSERT(ecb->dte_action == NULL);
                    ecb->dte_action = action;
          }

          ecb->dte_action_last = action;

          return (0);
}

static void
dtrace_ecb_action_remove(dtrace_ecb_t *ecb)
{
          dtrace_action_t *act = ecb->dte_action, *next;
          dtrace_vstate_t *vstate = &ecb->dte_state->dts_vstate;
          dtrace_difo_t *dp;
          uint16_t format;

          if (act != NULL && act->dta_refcnt > 1) {
                    ASSERT(act->dta_next == NULL || act->dta_next->dta_refcnt == 1);
                    act->dta_refcnt--;
          } else {
                    for (; act != NULL; act = next) {
                              next = act->dta_next;
                              ASSERT(next != NULL || act == ecb->dte_action_last);
                              ASSERT(act->dta_refcnt == 1);

                              if ((format = act->dta_rec.dtrd_format) != 0)
                                        dtrace_format_remove(ecb->dte_state, format);

                              if ((dp = act->dta_difo) != NULL)
                                        dtrace_difo_release(dp, vstate);

                              if (DTRACEACT_ISAGG(act->dta_kind)) {
                                        dtrace_ecb_aggregation_destroy(ecb, act);
                              } else {
                                        kmem_free(act, sizeof (dtrace_action_t));
                              }
                    }
          }

          ecb->dte_action = NULL;
          ecb->dte_action_last = NULL;
          ecb->dte_size = 0;
}

static void
dtrace_ecb_disable(dtrace_ecb_t *ecb)
{
          /*
           * We disable the ECB by removing it from its probe.
           */
          dtrace_ecb_t *pecb, *prev = NULL;
          dtrace_probe_t *probe = ecb->dte_probe;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (probe == NULL) {
                    /*
                     * This is the NULL probe; there is nothing to disable.
                     */
                    return;
          }

          for (pecb = probe->dtpr_ecb; pecb != NULL; pecb = pecb->dte_next) {
                    if (pecb == ecb)
                              break;
                    prev = pecb;
          }

          ASSERT(pecb != NULL);

          if (prev == NULL) {
                    probe->dtpr_ecb = ecb->dte_next;
          } else {
                    prev->dte_next = ecb->dte_next;
          }

          if (ecb == probe->dtpr_ecb_last) {
                    ASSERT(ecb->dte_next == NULL);
                    probe->dtpr_ecb_last = prev;
          }

          /*
           * The ECB has been disconnected from the probe; now sync to assure
           * that all CPUs have seen the change before returning.
           */
          dtrace_sync();

          if (probe->dtpr_ecb == NULL) {
                    /*
                     * That was the last ECB on the probe; clear the predicate
                     * cache ID for the probe, disable it and sync one more time
                     * to assure that we'll never hit it again.
                     */
                    dtrace_provider_t *prov = probe->dtpr_provider;

                    ASSERT(ecb->dte_next == NULL);
                    ASSERT(probe->dtpr_ecb_last == NULL);
                    probe->dtpr_predcache = DTRACE_CACHEIDNONE;
                    prov->dtpv_pops.dtps_disable(prov->dtpv_arg,
                        probe->dtpr_id, probe->dtpr_arg);
                    dtrace_sync();
          } else {
                    /*
                     * There is at least one ECB remaining on the probe.  If there
                     * is _exactly_ one, set the probe's predicate cache ID to be
                     * the predicate cache ID of the remaining ECB.
                     */
                    ASSERT(probe->dtpr_ecb_last != NULL);
                    ASSERT(probe->dtpr_predcache == DTRACE_CACHEIDNONE);

                    if (probe->dtpr_ecb == probe->dtpr_ecb_last) {
                              dtrace_predicate_t *p = probe->dtpr_ecb->dte_predicate;

                              ASSERT(probe->dtpr_ecb->dte_next == NULL);

                              if (p != NULL)
                                        probe->dtpr_predcache = p->dtp_cacheid;
                    }

                    ecb->dte_next = NULL;
          }
}

static void
dtrace_ecb_destroy(dtrace_ecb_t *ecb)
{
          dtrace_state_t *state = ecb->dte_state;
          dtrace_vstate_t *vstate = &state->dts_vstate;
          dtrace_predicate_t *pred;
          dtrace_epid_t epid = ecb->dte_epid;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(ecb->dte_next == NULL);
          ASSERT(ecb->dte_probe == NULL || ecb->dte_probe->dtpr_ecb != ecb);

          if ((pred = ecb->dte_predicate) != NULL)
                    dtrace_predicate_release(pred, vstate);

          dtrace_ecb_action_remove(ecb);

          ASSERT(state->dts_ecbs[epid - 1] == ecb);
          state->dts_ecbs[epid - 1] = NULL;

          kmem_free(ecb, sizeof (dtrace_ecb_t));
}

static dtrace_ecb_t *
dtrace_ecb_create(dtrace_state_t *state, dtrace_probe_t *probe,
    dtrace_enabling_t *enab)
{
          dtrace_ecb_t *ecb;
          dtrace_predicate_t *pred;
          dtrace_actdesc_t *act;
          dtrace_provider_t *prov;
          dtrace_ecbdesc_t *desc = enab->dten_current;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(state != NULL);

          ecb = dtrace_ecb_add(state, probe);
          ecb->dte_uarg = desc->dted_uarg;

          if ((pred = desc->dted_pred.dtpdd_predicate) != NULL) {
                    dtrace_predicate_hold(pred);
                    ecb->dte_predicate = pred;
          }

          if (probe != NULL) {
                    /*
                     * If the provider shows more leg than the consumer is old
                     * enough to see, we need to enable the appropriate implicit
                     * predicate bits to prevent the ecb from activating at
                     * revealing times.
                     *
                     * Providers specifying DTRACE_PRIV_USER at register time
                     * are stating that they need the /proc-style privilege
                     * model to be enforced, and this is what DTRACE_COND_OWNER
                     * and DTRACE_COND_ZONEOWNER will then do at probe time.
                     */
                    prov = probe->dtpr_provider;
                    if (!(state->dts_cred.dcr_visible & DTRACE_CRV_ALLPROC) &&
                        (prov->dtpv_priv.dtpp_flags & DTRACE_PRIV_USER))
                              ecb->dte_cond |= DTRACE_COND_OWNER;

                    if (!(state->dts_cred.dcr_visible & DTRACE_CRV_ALLZONE) &&
                        (prov->dtpv_priv.dtpp_flags & DTRACE_PRIV_USER))
                              ecb->dte_cond |= DTRACE_COND_ZONEOWNER;

                    /*
                     * If the provider shows us kernel innards and the user
                     * is lacking sufficient privilege, enable the
                     * DTRACE_COND_USERMODE implicit predicate.
                     */
                    if (!(state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL) &&
                        (prov->dtpv_priv.dtpp_flags & DTRACE_PRIV_KERNEL))
                              ecb->dte_cond |= DTRACE_COND_USERMODE;
          }

          if (dtrace_ecb_create_cache != NULL) {
                    /*
                     * If we have a cached ecb, we'll use its action list instead
                     * of creating our own (saving both time and space).
                     */
                    dtrace_ecb_t *cached = dtrace_ecb_create_cache;
                    dtrace_action_t *act = cached->dte_action;

                    if (act != NULL) {
                              ASSERT(act->dta_refcnt > 0);
                              act->dta_refcnt++;
                              ecb->dte_action = act;
                              ecb->dte_action_last = cached->dte_action_last;
                              ecb->dte_needed = cached->dte_needed;
                              ecb->dte_size = cached->dte_size;
                              ecb->dte_alignment = cached->dte_alignment;
                    }

                    return (ecb);
          }

          for (act = desc->dted_action; act != NULL; act = act->dtad_next) {
                    if ((enab->dten_error = dtrace_ecb_action_add(ecb, act)) != 0) {
                              dtrace_ecb_destroy(ecb);
                              return (NULL);
                    }
          }

          if ((enab->dten_error = dtrace_ecb_resize(ecb)) != 0) {
                    dtrace_ecb_destroy(ecb);
                    return (NULL);
          }

          return (dtrace_ecb_create_cache = ecb);
}

static int
dtrace_ecb_create_enable(dtrace_probe_t *probe, void *arg)
{
          dtrace_ecb_t *ecb;
          dtrace_enabling_t *enab = arg;
          dtrace_state_t *state = enab->dten_vstate->dtvs_state;

          ASSERT(state != NULL);

          if (probe != NULL && probe->dtpr_gen < enab->dten_probegen) {
                    /*
                     * This probe was created in a generation for which this
                     * enabling has previously created ECBs; we don't want to
                     * enable it again, so just kick out.
                     */
                    return (DTRACE_MATCH_NEXT);
          }

          if ((ecb = dtrace_ecb_create(state, probe, enab)) == NULL)
                    return (DTRACE_MATCH_DONE);

          if (dtrace_ecb_enable(ecb) < 0)
                    return (DTRACE_MATCH_FAIL);

          return (DTRACE_MATCH_NEXT);
}

static dtrace_ecb_t *
dtrace_epid2ecb(dtrace_state_t *state, dtrace_epid_t id)
{
          dtrace_ecb_t *ecb;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (id == 0 || id > state->dts_necbs)
                    return (NULL);

          ASSERT(state->dts_necbs > 0 && state->dts_ecbs != NULL);
          ASSERT((ecb = state->dts_ecbs[id - 1]) == NULL || ecb->dte_epid == id);

          return (state->dts_ecbs[id - 1]);
}

static dtrace_aggregation_t *
dtrace_aggid2agg(dtrace_state_t *state, dtrace_aggid_t id)
{
          dtrace_aggregation_t *agg;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (id == 0 || id > state->dts_naggregations)
                    return (NULL);

          ASSERT(state->dts_naggregations > 0 && state->dts_aggregations != NULL);
          ASSERT((agg = state->dts_aggregations[id - 1]) == NULL ||
              agg->dtag_id == id);

          return (state->dts_aggregations[id - 1]);
}

/*
 * DTrace Buffer Functions
 *
 * The following functions manipulate DTrace buffers.  Most of these functions
 * are called in the context of establishing or processing consumer state;
 * exceptions are explicitly noted.
 */

/*
 * Note:  called from cross call context.  This function switches the two
 * buffers on a given CPU.  The atomicity of this operation is assured by
 * disabling interrupts while the actual switch takes place; the disabling of
 * interrupts serializes the execution with any execution of dtrace_probe() on
 * the same CPU.
 */
static void
dtrace_buffer_switch(dtrace_buffer_t *buf)
{
          caddr_t tomax = buf->dtb_tomax;
          caddr_t xamot = buf->dtb_xamot;
          dtrace_icookie_t cookie;
          hrtime_t now;

          ASSERT(!(buf->dtb_flags & DTRACEBUF_NOSWITCH));
          ASSERT(!(buf->dtb_flags & DTRACEBUF_RING));

          cookie = dtrace_interrupt_disable();
          now = dtrace_gethrtime();
          buf->dtb_tomax = xamot;
          buf->dtb_xamot = tomax;
          buf->dtb_xamot_drops = buf->dtb_drops;
          buf->dtb_xamot_offset = buf->dtb_offset;
          buf->dtb_xamot_errors = buf->dtb_errors;
          buf->dtb_xamot_flags = buf->dtb_flags;
          buf->dtb_offset = 0;
          buf->dtb_drops = 0;
          buf->dtb_errors = 0;
          buf->dtb_flags &= ~(DTRACEBUF_ERROR | DTRACEBUF_DROPPED);
          buf->dtb_interval = now - buf->dtb_switched;
          buf->dtb_switched = now;
          dtrace_interrupt_enable(cookie);
}

/*
 * Note:  called from cross call context.  This function activates a buffer
 * on a CPU.  As with dtrace_buffer_switch(), the atomicity of the operation
 * is guaranteed by the disabling of interrupts.
 */
static void
dtrace_buffer_activate(dtrace_state_t *state)
{
          dtrace_buffer_t *buf;
          dtrace_icookie_t cookie = dtrace_interrupt_disable();

          buf = &state->dts_buffer[curcpu_id];

          if (buf->dtb_tomax != NULL) {
                    /*
                     * We might like to assert that the buffer is marked inactive,
                     * but this isn't necessarily true:  the buffer for the CPU
                     * that processes the BEGIN probe has its buffer activated
                     * manually.  In this case, we take the (harmless) action
                     * re-clearing the bit INACTIVE bit.
                     */
                    buf->dtb_flags &= ~DTRACEBUF_INACTIVE;
          }

          dtrace_interrupt_enable(cookie);
}

#ifdef __FreeBSD__
/*
 * Activate the specified per-CPU buffer.  This is used instead of
 * dtrace_buffer_activate() when APs have not yet started, i.e. when
 * activating anonymous state.
 */
static void
dtrace_buffer_activate_cpu(dtrace_state_t *state, int cpu)
{

          if (state->dts_buffer[cpu].dtb_tomax != NULL)
                    state->dts_buffer[cpu].dtb_flags &= ~DTRACEBUF_INACTIVE;
}
#endif

static int
dtrace_buffer_alloc(dtrace_buffer_t *bufs, size_t size, int flags,
    processorid_t cpu, int *factor)
{
#ifdef illumos
          cpu_t *cp;
#endif
#ifdef __NetBSD__
          CPU_INFO_ITERATOR cpuind;
          struct cpu_info *cinfo;
#endif
          dtrace_buffer_t *buf;
          int allocated = 0, desired = 0;

#ifdef illumos
          ASSERT(MUTEX_HELD(&cpu_lock));
          ASSERT(MUTEX_HELD(&dtrace_lock));

          *factor = 1;

          if (size > dtrace_nonroot_maxsize &&
              !PRIV_POLICY_CHOICE(CRED(), PRIV_ALL, B_FALSE))
                    return (EFBIG);

          cp = cpu_list;

          do {
                    if (cpu != DTRACE_CPUALL && cpu != cp->cpu_id)
                              continue;

                    buf = &bufs[cp->cpu_id];

                    /*
                     * If there is already a buffer allocated for this CPU, it
                     * is only possible that this is a DR event.  In this case,
                     */
                    if (buf->dtb_tomax != NULL) {
                              ASSERT(buf->dtb_size == size);
                              continue;
                    }

                    ASSERT(buf->dtb_xamot == NULL);

                    if ((buf->dtb_tomax = kmem_zalloc(size,
                        KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                              goto err;

                    buf->dtb_size = size;
                    buf->dtb_flags = flags;
                    buf->dtb_offset = 0;
                    buf->dtb_drops = 0;

                    if (flags & DTRACEBUF_NOSWITCH)
                              continue;

                    if ((buf->dtb_xamot = kmem_zalloc(size,
                        KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                              goto err;
          } while ((cp = cp->cpu_next) != cpu_list);

          return (0);

err:
          cp = cpu_list;

          do {
                    if (cpu != DTRACE_CPUALL && cpu != cp->cpu_id)
                              continue;

                    buf = &bufs[cp->cpu_id];
                    desired += 2;

                    if (buf->dtb_xamot != NULL) {
                              ASSERT(buf->dtb_tomax != NULL);
                              ASSERT(buf->dtb_size == size);
                              kmem_free(buf->dtb_xamot, size);
                              allocated++;
                    }

                    if (buf->dtb_tomax != NULL) {
                              ASSERT(buf->dtb_size == size);
                              kmem_free(buf->dtb_tomax, size);
                              allocated++;
                    }

                    buf->dtb_tomax = NULL;
                    buf->dtb_xamot = NULL;
                    buf->dtb_size = 0;
          } while ((cp = cp->cpu_next) != cpu_list);
#else

          *factor = 1;
#if defined(__aarch64__) || defined(__amd64__) || defined(__arm__) || \
    defined(__mips__) || defined(__powerpc__) || defined(__riscv__)
          /*
           * FreeBSD isn't good at limiting the amount of memory we
           * ask to malloc, so let's place a limit here before trying
           * to do something that might well end in tears at bedtime.
           */
          if (size > physmem * PAGE_SIZE / (128 * (mp_maxid + 1)))
                    return (ENOMEM);
#endif

          ASSERT(MUTEX_HELD(&dtrace_lock));
#ifdef __NetBSD__
          for (CPU_INFO_FOREACH(cpuind, cinfo))
#else
          CPU_FOREACH(i)
#endif
          {
#ifdef __NetBSD__
                    int i = cpu_index(cinfo);
#endif
                    if (cpu != DTRACE_CPUALL && cpu != i)
                              continue;

                    buf = &bufs[i];

                    /*
                     * If there is already a buffer allocated for this CPU, it
                     * is only possible that this is a DR event.  In this case,
                     * the buffer size must match our specified size.
                     */
                    if (buf->dtb_tomax != NULL) {
                              ASSERT(buf->dtb_size == size);
                              continue;
                    }

                    ASSERT(buf->dtb_xamot == NULL);

                    if ((buf->dtb_tomax = kmem_zalloc(size,
                        KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                              goto err;

                    buf->dtb_size = size;
                    buf->dtb_flags = flags;
                    buf->dtb_offset = 0;
                    buf->dtb_drops = 0;

                    if (flags & DTRACEBUF_NOSWITCH)
                              continue;

                    if ((buf->dtb_xamot = kmem_zalloc(size,
                        KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                              goto err;
          }

          return (0);

err:
          /*
           * Error allocating memory, so free the buffers that were
           * allocated before the failed allocation.
           */
#ifdef __NetBSD__
          for (CPU_INFO_FOREACH(cpuind, cinfo))
#else
          CPU_FOREACH(i)
#endif
          {
#ifdef __NetBSD__
                    int i = cpu_index(cinfo);
#endif
                    if (cpu != DTRACE_CPUALL && cpu != cpu_index(cinfo))
                              continue;

                    buf = &bufs[i];
                    desired += 2;

                    if (buf->dtb_xamot != NULL) {
                              ASSERT(buf->dtb_tomax != NULL);
                              ASSERT(buf->dtb_size == size);
                              kmem_free(buf->dtb_xamot, size);
                              allocated++;
                    }

                    if (buf->dtb_tomax != NULL) {
                              ASSERT(buf->dtb_size == size);
                              kmem_free(buf->dtb_tomax, size);
                              allocated++;
                    }

                    buf->dtb_tomax = NULL;
                    buf->dtb_xamot = NULL;
                    buf->dtb_size = 0;

          }
#endif
          *factor = desired / (allocated > 0 ? allocated : 1);

          return (ENOMEM);
}

/*
 * Note:  called from probe context.  This function just increments the drop
 * count on a buffer.  It has been made a function to allow for the
 * possibility of understanding the source of mysterious drop counts.  (A
 * problem for which one may be particularly disappointed that DTrace cannot
 * be used to understand DTrace.)
 */
static void
dtrace_buffer_drop(dtrace_buffer_t *buf)
{
          buf->dtb_drops++;
}

/*
 * Note:  called from probe context.  This function is called to reserve space
 * in a buffer.  If mstate is non-NULL, sets the scratch base and size in the
 * mstate.  Returns the new offset in the buffer, or a negative value if an
 * error has occurred.
 */
static intptr_t
dtrace_buffer_reserve(dtrace_buffer_t *buf, size_t needed, size_t align,
    dtrace_state_t *state, dtrace_mstate_t *mstate)
{
          intptr_t offs = buf->dtb_offset, soffs;
          intptr_t woffs;
          caddr_t tomax;
          size_t total;

          if (buf->dtb_flags & DTRACEBUF_INACTIVE)
                    return (-1);

          if ((tomax = buf->dtb_tomax) == NULL) {
                    dtrace_buffer_drop(buf);
                    return (-1);
          }

          if (!(buf->dtb_flags & (DTRACEBUF_RING | DTRACEBUF_FILL))) {
                    while (offs & (align - 1)) {
                              /*
                               * Assert that our alignment is off by a number which
                               * is itself sizeof (uint32_t) aligned.
                               */
                              ASSERT(!((align - (offs & (align - 1))) &
                                  (sizeof (uint32_t) - 1)));
                              DTRACE_STORE(uint32_t, tomax, offs, DTRACE_EPIDNONE);
                              offs += sizeof (uint32_t);
                    }

                    if ((soffs = offs + needed) > buf->dtb_size) {
                              dtrace_buffer_drop(buf);
                              return (-1);
                    }

                    if (mstate == NULL)
                              return (offs);

                    mstate->dtms_scratch_base = (uintptr_t)tomax + soffs;
                    mstate->dtms_scratch_size = buf->dtb_size - soffs;
                    mstate->dtms_scratch_ptr = mstate->dtms_scratch_base;

                    return (offs);
          }

          if (buf->dtb_flags & DTRACEBUF_FILL) {
                    if (state->dts_activity != DTRACE_ACTIVITY_COOLDOWN &&
                        (buf->dtb_flags & DTRACEBUF_FULL))
                              return (-1);
                    goto out;
          }

          total = needed + (offs & (align - 1));

          /*
           * For a ring buffer, life is quite a bit more complicated.  Before
           * we can store any padding, we need to adjust our wrapping offset.
           * (If we've never before wrapped or we're not about to, no adjustment
           * is required.)
           */
          if ((buf->dtb_flags & DTRACEBUF_WRAPPED) ||
              offs + total > buf->dtb_size) {
                    woffs = buf->dtb_xamot_offset;

                    if (offs + total > buf->dtb_size) {
                              /*
                               * We can't fit in the end of the buffer.  First, a
                               * sanity check that we can fit in the buffer at all.
                               */
                              if (total > buf->dtb_size) {
                                        dtrace_buffer_drop(buf);
                                        return (-1);
                              }

                              /*
                               * We're going to be storing at the top of the buffer,
                               * so now we need to deal with the wrapped offset.  We
                               * only reset our wrapped offset to 0 if it is
                               * currently greater than the current offset.  If it
                               * is less than the current offset, it is because a
                               * previous allocation induced a wrap -- but the
                               * allocation didn't subsequently take the space due
                               * to an error or false predicate evaluation.  In this
                               * case, we'll just leave the wrapped offset alone: if
                               * the wrapped offset hasn't been advanced far enough
                               * for this allocation, it will be adjusted in the
                               * lower loop.
                               */
                              if (buf->dtb_flags & DTRACEBUF_WRAPPED) {
                                        if (woffs >= offs)
                                                  woffs = 0;
                              } else {
                                        woffs = 0;
                              }

                              /*
                               * Now we know that we're going to be storing to the
                               * top of the buffer and that there is room for us
                               * there.  We need to clear the buffer from the current
                               * offset to the end (there may be old gunk there).
                               */
                              while (offs < buf->dtb_size)
                                        tomax[offs++] = 0;

                              /*
                               * We need to set our offset to zero.  And because we
                               * are wrapping, we need to set the bit indicating as
                               * much.  We can also adjust our needed space back
                               * down to the space required by the ECB -- we know
                               * that the top of the buffer is aligned.
                               */
                              offs = 0;
                              total = needed;
                              buf->dtb_flags |= DTRACEBUF_WRAPPED;
                    } else {
                              /*
                               * There is room for us in the buffer, so we simply
                               * need to check the wrapped offset.
                               */
                              if (woffs < offs) {
                                        /*
                                         * The wrapped offset is less than the offset.
                                         * This can happen if we allocated buffer space
                                         * that induced a wrap, but then we didn't
                                         * subsequently take the space due to an error
                                         * or false predicate evaluation.  This is
                                         * okay; we know that _this_ allocation isn't
                                         * going to induce a wrap.  We still can't
                                         * reset the wrapped offset to be zero,
                                         * however: the space may have been trashed in
                                         * the previous failed probe attempt.  But at
                                         * least the wrapped offset doesn't need to
                                         * be adjusted at all...
                                         */
                                        goto out;
                              }
                    }

                    while (offs + total > woffs) {
                              dtrace_epid_t epid = *(uint32_t *)(tomax + woffs);
                              size_t size;

                              if (epid == DTRACE_EPIDNONE) {
                                        size = sizeof (uint32_t);
                              } else {
                                        ASSERT3U(epid, <=, state->dts_necbs);
                                        ASSERT(state->dts_ecbs[epid - 1] != NULL);

                                        size = state->dts_ecbs[epid - 1]->dte_size;
                              }

                              ASSERT(woffs + size <= buf->dtb_size);
                              ASSERT(size != 0);

                              if (woffs + size == buf->dtb_size) {
                                        /*
                                         * We've reached the end of the buffer; we want
                                         * to set the wrapped offset to 0 and break
                                         * out.  However, if the offs is 0, then we're
                                         * in a strange edge-condition:  the amount of
                                         * space that we want to reserve plus the size
                                         * of the record that we're overwriting is
                                         * greater than the size of the buffer.  This
                                         * is problematic because if we reserve the
                                         * space but subsequently don't consume it (due
                                         * to a failed predicate or error) the wrapped
                                         * offset will be 0 -- yet the EPID at offset 0
                                         * will not be committed.  This situation is
                                         * relatively easy to deal with:  if we're in
                                         * this case, the buffer is indistinguishable
                                         * from one that hasn't wrapped; we need only
                                         * finish the job by clearing the wrapped bit,
                                         * explicitly setting the offset to be 0, and
                                         * zero'ing out the old data in the buffer.
                                         */
                                        if (offs == 0) {
                                                  buf->dtb_flags &= ~DTRACEBUF_WRAPPED;
                                                  buf->dtb_offset = 0;
                                                  woffs = total;

                                                  while (woffs < buf->dtb_size)
                                                            tomax[woffs++] = 0;
                                        }

                                        woffs = 0;
                                        break;
                              }

                              woffs += size;
                    }

                    /*
                     * We have a wrapped offset.  It may be that the wrapped offset
                     * has become zero -- that's okay.
                     */
                    buf->dtb_xamot_offset = woffs;
          }

out:
          /*
           * Now we can plow the buffer with any necessary padding.
           */
          while (offs & (align - 1)) {
                    /*
                     * Assert that our alignment is off by a number which
                     * is itself sizeof (uint32_t) aligned.
                     */
                    ASSERT(!((align - (offs & (align - 1))) &
                        (sizeof (uint32_t) - 1)));
                    DTRACE_STORE(uint32_t, tomax, offs, DTRACE_EPIDNONE);
                    offs += sizeof (uint32_t);
          }

          if (buf->dtb_flags & DTRACEBUF_FILL) {
                    if (offs + needed > buf->dtb_size - state->dts_reserve) {
                              buf->dtb_flags |= DTRACEBUF_FULL;
                              return (-1);
                    }
          }

          if (mstate == NULL)
                    return (offs);

          /*
           * For ring buffers and fill buffers, the scratch space is always
           * the inactive buffer.
           */
          mstate->dtms_scratch_base = (uintptr_t)buf->dtb_xamot;
          mstate->dtms_scratch_size = buf->dtb_size;
          mstate->dtms_scratch_ptr = mstate->dtms_scratch_base;

          return (offs);
}

static void
dtrace_buffer_polish(dtrace_buffer_t *buf)
{
          ASSERT(buf->dtb_flags & DTRACEBUF_RING);
          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (!(buf->dtb_flags & DTRACEBUF_WRAPPED))
                    return;

          /*
           * We need to polish the ring buffer.  There are three cases:
           *
           * - The first (and presumably most common) is that there is no gap
           *   between the buffer offset and the wrapped offset.  In this case,
           *   there is nothing in the buffer that isn't valid data; we can
           *   mark the buffer as polished and return.
           *
           * - The second (less common than the first but still more common
           *   than the third) is that there is a gap between the buffer offset
           *   and the wrapped offset, and the wrapped offset is larger than the
           *   buffer offset.  This can happen because of an alignment issue, or
           *   can happen because of a call to dtrace_buffer_reserve() that
           *   didn't subsequently consume the buffer space.  In this case,
           *   we need to zero the data from the buffer offset to the wrapped
           *   offset.
           *
           * - The third (and least common) is that there is a gap between the
           *   buffer offset and the wrapped offset, but the wrapped offset is
           *   _less_ than the buffer offset.  This can only happen because a
           *   call to dtrace_buffer_reserve() induced a wrap, but the space
           *   was not subsequently consumed.  In this case, we need to zero the
           *   space from the offset to the end of the buffer _and_ from the
           *   top of the buffer to the wrapped offset.
           */
          if (buf->dtb_offset < buf->dtb_xamot_offset) {
                    bzero(buf->dtb_tomax + buf->dtb_offset,
                        buf->dtb_xamot_offset - buf->dtb_offset);
          }

          if (buf->dtb_offset > buf->dtb_xamot_offset) {
                    bzero(buf->dtb_tomax + buf->dtb_offset,
                        buf->dtb_size - buf->dtb_offset);
                    bzero(buf->dtb_tomax, buf->dtb_xamot_offset);
          }
}

/*
 * This routine determines if data generated at the specified time has likely
 * been entirely consumed at user-level.  This routine is called to determine
 * if an ECB on a defunct probe (but for an active enabling) can be safely
 * disabled and destroyed.
 */
static int
dtrace_buffer_consumed(dtrace_buffer_t *bufs, hrtime_t when)
{
          int i;

          for (i = 0; i < NCPU; i++) {
                    dtrace_buffer_t *buf = &bufs[i];

                    if (buf->dtb_size == 0)
                              continue;

                    if (buf->dtb_flags & DTRACEBUF_RING)
                              return (0);

                    if (!buf->dtb_switched && buf->dtb_offset != 0)
                              return (0);

                    if (buf->dtb_switched - buf->dtb_interval < when)
                              return (0);
          }

          return (1);
}

static void
dtrace_buffer_free(dtrace_buffer_t *bufs)
{
          int i;

          for (i = 0; i < NCPU; i++) {
                    dtrace_buffer_t *buf = &bufs[i];

                    if (buf->dtb_tomax == NULL) {
                              ASSERT(buf->dtb_xamot == NULL);
                              ASSERT(buf->dtb_size == 0);
                              continue;
                    }

                    if (buf->dtb_xamot != NULL) {
                              ASSERT(!(buf->dtb_flags & DTRACEBUF_NOSWITCH));
                              kmem_free(buf->dtb_xamot, buf->dtb_size);
                    }

                    kmem_free(buf->dtb_tomax, buf->dtb_size);
                    buf->dtb_size = 0;
                    buf->dtb_tomax = NULL;
                    buf->dtb_xamot = NULL;
          }
}

/*
 * DTrace Enabling Functions
 */
static dtrace_enabling_t *
dtrace_enabling_create(dtrace_vstate_t *vstate)
{
          dtrace_enabling_t *enab;

          enab = kmem_zalloc(sizeof (dtrace_enabling_t), KM_SLEEP);
          enab->dten_vstate = vstate;

          return (enab);
}

static void
dtrace_enabling_add(dtrace_enabling_t *enab, dtrace_ecbdesc_t *ecb)
{
          dtrace_ecbdesc_t **ndesc;
          size_t osize, nsize;

          /*
           * We can't add to enablings after we've enabled them, or after we've
           * retained them.
           */
          ASSERT(enab->dten_probegen == 0);
          ASSERT(enab->dten_next == NULL && enab->dten_prev == NULL);

          if (enab->dten_ndesc < enab->dten_maxdesc) {
                    enab->dten_desc[enab->dten_ndesc++] = ecb;
                    return;
          }

          osize = enab->dten_maxdesc * sizeof (dtrace_enabling_t *);

          if (enab->dten_maxdesc == 0) {
                    enab->dten_maxdesc = 1;
          } else {
                    enab->dten_maxdesc <<= 1;
          }

          ASSERT(enab->dten_ndesc < enab->dten_maxdesc);

          nsize = enab->dten_maxdesc * sizeof (dtrace_enabling_t *);
          ndesc = kmem_zalloc(nsize, KM_SLEEP);
          bcopy(enab->dten_desc, ndesc, osize);
          if (enab->dten_desc != NULL)
                    kmem_free(enab->dten_desc, osize);

          enab->dten_desc = ndesc;
          enab->dten_desc[enab->dten_ndesc++] = ecb;
}

static void
dtrace_enabling_addlike(dtrace_enabling_t *enab, dtrace_ecbdesc_t *ecb,
    dtrace_probedesc_t *pd)
{
          dtrace_ecbdesc_t *new;
          dtrace_predicate_t *pred;
          dtrace_actdesc_t *act;

          /*
           * We're going to create a new ECB description that matches the
           * specified ECB in every way, but has the specified probe description.
           */
          new = kmem_zalloc(sizeof (dtrace_ecbdesc_t), KM_SLEEP);

          if ((pred = ecb->dted_pred.dtpdd_predicate) != NULL)
                    dtrace_predicate_hold(pred);

          for (act = ecb->dted_action; act != NULL; act = act->dtad_next)
                    dtrace_actdesc_hold(act);

          new->dted_action = ecb->dted_action;
          new->dted_pred = ecb->dted_pred;
          new->dted_probe = *pd;
          new->dted_uarg = ecb->dted_uarg;

          dtrace_enabling_add(enab, new);
}

static void
dtrace_enabling_dump(dtrace_enabling_t *enab)
{
          int i;

          for (i = 0; i < enab->dten_ndesc; i++) {
                    dtrace_probedesc_t *desc = &enab->dten_desc[i]->dted_probe;

#ifdef __FreeBSD__
                    printf("dtrace: enabling probe %d (%s:%s:%s:%s)\n", i,
                        desc->dtpd_provider, desc->dtpd_mod,
                        desc->dtpd_func, desc->dtpd_name);
#else
                    cmn_err(CE_NOTE, "enabling probe %d (%s:%s:%s:%s)", i,
                        desc->dtpd_provider, desc->dtpd_mod,
                        desc->dtpd_func, desc->dtpd_name);
#endif
          }
}

static void
dtrace_enabling_destroy(dtrace_enabling_t *enab)
{
          int i;
          dtrace_ecbdesc_t *ep;
          dtrace_vstate_t *vstate = enab->dten_vstate;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          for (i = 0; i < enab->dten_ndesc; i++) {
                    dtrace_actdesc_t *act, *next;
                    dtrace_predicate_t *pred;

                    ep = enab->dten_desc[i];

                    if ((pred = ep->dted_pred.dtpdd_predicate) != NULL)
                              dtrace_predicate_release(pred, vstate);

                    for (act = ep->dted_action; act != NULL; act = next) {
                              next = act->dtad_next;
                              dtrace_actdesc_release(act, vstate);
                    }

                    kmem_free(ep, sizeof (dtrace_ecbdesc_t));
          }

          if (enab->dten_desc != NULL)
                    kmem_free(enab->dten_desc,
                        enab->dten_maxdesc * sizeof (dtrace_enabling_t *));

          /*
           * If this was a retained enabling, decrement the dts_nretained count
           * and take it off of the dtrace_retained list.
           */
          if (enab->dten_prev != NULL || enab->dten_next != NULL ||
              dtrace_retained == enab) {
                    ASSERT(enab->dten_vstate->dtvs_state != NULL);
                    ASSERT(enab->dten_vstate->dtvs_state->dts_nretained > 0);
                    enab->dten_vstate->dtvs_state->dts_nretained--;
                    dtrace_retained_gen++;
          }

          if (enab->dten_prev == NULL) {
                    if (dtrace_retained == enab) {
                              dtrace_retained = enab->dten_next;

                              if (dtrace_retained != NULL)
                                        dtrace_retained->dten_prev = NULL;
                    }
          } else {
                    ASSERT(enab != dtrace_retained);
                    ASSERT(dtrace_retained != NULL);
                    enab->dten_prev->dten_next = enab->dten_next;
          }

          if (enab->dten_next != NULL) {
                    ASSERT(dtrace_retained != NULL);
                    enab->dten_next->dten_prev = enab->dten_prev;
          }

          kmem_free(enab, sizeof (dtrace_enabling_t));
}

static int
dtrace_enabling_retain(dtrace_enabling_t *enab)
{
          dtrace_state_t *state;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(enab->dten_next == NULL && enab->dten_prev == NULL);
          ASSERT(enab->dten_vstate != NULL);

          state = enab->dten_vstate->dtvs_state;
          ASSERT(state != NULL);

          /*
           * We only allow each state to retain dtrace_retain_max enablings.
           */
          if (state->dts_nretained >= dtrace_retain_max)
                    return (ENOSPC);

          state->dts_nretained++;
          dtrace_retained_gen++;

          if (dtrace_retained == NULL) {
                    dtrace_retained = enab;
                    return (0);
          }

          enab->dten_next = dtrace_retained;
          dtrace_retained->dten_prev = enab;
          dtrace_retained = enab;

          return (0);
}

static int
dtrace_enabling_replicate(dtrace_state_t *state, dtrace_probedesc_t *match,
    dtrace_probedesc_t *create)
{
          dtrace_enabling_t *new, *enab;
          int found = 0, err = ENOENT;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(strlen(match->dtpd_provider) < DTRACE_PROVNAMELEN);
          ASSERT(strlen(match->dtpd_mod) < DTRACE_MODNAMELEN);
          ASSERT(strlen(match->dtpd_func) < DTRACE_FUNCNAMELEN);
          ASSERT(strlen(match->dtpd_name) < DTRACE_NAMELEN);

          new = dtrace_enabling_create(&state->dts_vstate);

          /*
           * Iterate over all retained enablings, looking for enablings that
           * match the specified state.
           */
          for (enab = dtrace_retained; enab != NULL; enab = enab->dten_next) {
                    int i;

                    /*
                     * dtvs_state can only be NULL for helper enablings -- and
                     * helper enablings can't be retained.
                     */
                    ASSERT(enab->dten_vstate->dtvs_state != NULL);

                    if (enab->dten_vstate->dtvs_state != state)
                              continue;

                    /*
                     * Now iterate over each probe description; we're looking for
                     * an exact match to the specified probe description.
                     */
                    for (i = 0; i < enab->dten_ndesc; i++) {
                              dtrace_ecbdesc_t *ep = enab->dten_desc[i];
                              dtrace_probedesc_t *pd = &ep->dted_probe;

                              if (strcmp(pd->dtpd_provider, match->dtpd_provider))
                                        continue;

                              if (strcmp(pd->dtpd_mod, match->dtpd_mod))
                                        continue;

                              if (strcmp(pd->dtpd_func, match->dtpd_func))
                                        continue;

                              if (strcmp(pd->dtpd_name, match->dtpd_name))
                                        continue;

                              /*
                               * We have a winning probe!  Add it to our growing
                               * enabling.
                               */
                              found = 1;
                              dtrace_enabling_addlike(new, ep, create);
                    }
          }

          if (!found || (err = dtrace_enabling_retain(new)) != 0) {
                    dtrace_enabling_destroy(new);
                    return (err);
          }

          return (0);
}

static void
dtrace_enabling_retract(dtrace_state_t *state)
{
          dtrace_enabling_t *enab, *next;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          /*
           * Iterate over all retained enablings, destroy the enablings retained
           * for the specified state.
           */
          for (enab = dtrace_retained; enab != NULL; enab = next) {
                    next = enab->dten_next;

                    /*
                     * dtvs_state can only be NULL for helper enablings -- and
                     * helper enablings can't be retained.
                     */
                    ASSERT(enab->dten_vstate->dtvs_state != NULL);

                    if (enab->dten_vstate->dtvs_state == state) {
                              ASSERT(state->dts_nretained > 0);
                              dtrace_enabling_destroy(enab);
                    }
          }

          ASSERT(state->dts_nretained == 0);
}

static int
dtrace_enabling_match(dtrace_enabling_t *enab, int *nmatched)
{
          int i = 0;
          int total_matched = 0, matched = 0;

          ASSERT(MUTEX_HELD(&cpu_lock));
          ASSERT(MUTEX_HELD(&dtrace_lock));

          for (i = 0; i < enab->dten_ndesc; i++) {
                    dtrace_ecbdesc_t *ep = enab->dten_desc[i];

                    enab->dten_current = ep;
                    enab->dten_error = 0;

                    /*
                     * If a provider failed to enable a probe then get out and
                     * let the consumer know we failed.
                     */
                    if ((matched = dtrace_probe_enable(&ep->dted_probe, enab)) < 0)
                              return (EBUSY);

                    total_matched += matched;

                    if (enab->dten_error != 0) {
                              /*
                               * If we get an error half-way through enabling the
                               * probes, we kick out -- perhaps with some number of
                               * them enabled.  Leaving enabled probes enabled may
                               * be slightly confusing for user-level, but we expect
                               * that no one will attempt to actually drive on in
                               * the face of such errors.  If this is an anonymous
                               * enabling (indicated with a NULL nmatched pointer),
                               * we cmn_err() a message.  We aren't expecting to
                               * get such an error -- such as it can exist at all,
                               * it would be a result of corrupted DOF in the driver
                               * properties.
                               */
                              if (nmatched == NULL) {
                                        cmn_err(CE_WARN, "dtrace_enabling_match() "
                                            "error on %p: %d", (void *)ep,
                                            enab->dten_error);
                              }

                              return (enab->dten_error);
                    }
          }

          enab->dten_probegen = dtrace_probegen;
          if (nmatched != NULL)
                    *nmatched = total_matched;

          return (0);
}

static void
dtrace_enabling_matchall(void)
{
          dtrace_enabling_t *enab;

          mutex_enter(&cpu_lock);
          mutex_enter(&dtrace_lock);

          /*
           * Iterate over all retained enablings to see if any probes match
           * against them.  We only perform this operation on enablings for which
           * we have sufficient permissions by virtue of being in the global zone
           * or in the same zone as the DTrace client.  Because we can be called
           * after dtrace_detach() has been called, we cannot assert that there
           * are retained enablings.  We can safely load from dtrace_retained,
           * however:  the taskq_destroy() at the end of dtrace_detach() will
           * block pending our completion.
           */
          for (enab = dtrace_retained; enab != NULL; enab = enab->dten_next) {
#ifdef illumos
                    cred_t *cr = enab->dten_vstate->dtvs_state->dts_cred.dcr_cred;

                    if (INGLOBALZONE(curproc) ||
                        cr != NULL && getzoneid() == crgetzoneid(cr))
#endif
                              (void) dtrace_enabling_match(enab, NULL);
          }

          mutex_exit(&dtrace_lock);
          mutex_exit(&cpu_lock);
}

/*
 * If an enabling is to be enabled without having matched probes (that is, if
 * dtrace_state_go() is to be called on the underlying dtrace_state_t), the
 * enabling must be _primed_ by creating an ECB for every ECB description.
 * This must be done to assure that we know the number of speculations, the
 * number of aggregations, the minimum buffer size needed, etc. before we
 * transition out of DTRACE_ACTIVITY_INACTIVE.  To do this without actually
 * enabling any probes, we create ECBs for every ECB decription, but with a
 * NULL probe -- which is exactly what this function does.
 */
static void
dtrace_enabling_prime(dtrace_state_t *state)
{
          dtrace_enabling_t *enab;
          int i;

          for (enab = dtrace_retained; enab != NULL; enab = enab->dten_next) {
                    ASSERT(enab->dten_vstate->dtvs_state != NULL);

                    if (enab->dten_vstate->dtvs_state != state)
                              continue;

                    /*
                     * We don't want to prime an enabling more than once, lest
                     * we allow a malicious user to induce resource exhaustion.
                     * (The ECBs that result from priming an enabling aren't
                     * leaked -- but they also aren't deallocated until the
                     * consumer state is destroyed.)
                     */
                    if (enab->dten_primed)
                              continue;

                    for (i = 0; i < enab->dten_ndesc; i++) {
                              enab->dten_current = enab->dten_desc[i];
                              (void) dtrace_probe_enable(NULL, enab);
                    }

                    enab->dten_primed = 1;
          }
}

/*
 * Called to indicate that probes should be provided due to retained
 * enablings.  This is implemented in terms of dtrace_probe_provide(), but it
 * must take an initial lap through the enabling calling the dtps_provide()
 * entry point explicitly to allow for autocreated probes.
 */
static void
dtrace_enabling_provide(dtrace_provider_t *prv)
{
          int i, all = 0;
          dtrace_probedesc_t desc;
          dtrace_genid_t gen;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(MUTEX_HELD(&dtrace_provider_lock));

          if (prv == NULL) {
                    all = 1;
                    prv = dtrace_provider;
          }

          do {
                    dtrace_enabling_t *enab;
                    void *parg = prv->dtpv_arg;

retry:
                    gen = dtrace_retained_gen;
                    for (enab = dtrace_retained; enab != NULL;
                        enab = enab->dten_next) {
                              for (i = 0; i < enab->dten_ndesc; i++) {
                                        desc = enab->dten_desc[i]->dted_probe;
                                        mutex_exit(&dtrace_lock);
                                        prv->dtpv_pops.dtps_provide(parg, &desc);
                                        mutex_enter(&dtrace_lock);
                                        /*
                                         * Process the retained enablings again if
                                         * they have changed while we weren't holding
                                         * dtrace_lock.
                                         */
                                        if (gen != dtrace_retained_gen)
                                                  goto retry;
                              }
                    }
          } while (all && (prv = prv->dtpv_next) != NULL);

          mutex_exit(&dtrace_lock);
          dtrace_probe_provide(NULL, all ? NULL : prv);
          mutex_enter(&dtrace_lock);
}

/*
 * Called to reap ECBs that are attached to probes from defunct providers.
 */
static void
dtrace_enabling_reap(void)
{
          dtrace_provider_t *prov;
          dtrace_probe_t *probe;
          dtrace_ecb_t *ecb;
          hrtime_t when;
          int i;

          mutex_enter(&cpu_lock);
          mutex_enter(&dtrace_lock);

          for (i = 0; i < dtrace_nprobes; i++) {
                    if ((probe = dtrace_probes[i]) == NULL)
                              continue;

                    if (probe->dtpr_ecb == NULL)
                              continue;

                    prov = probe->dtpr_provider;

                    if ((when = prov->dtpv_defunct) == 0)
                              continue;

                    /*
                     * We have ECBs on a defunct provider:  we want to reap these
                     * ECBs to allow the provider to unregister.  The destruction
                     * of these ECBs must be done carefully:  if we destroy the ECB
                     * and the consumer later wishes to consume an EPID that
                     * corresponds to the destroyed ECB (and if the EPID metadata
                     * has not been previously consumed), the consumer will abort
                     * processing on the unknown EPID.  To reduce (but not, sadly,
                     * eliminate) the possibility of this, we will only destroy an
                     * ECB for a defunct provider if, for the state that
                     * corresponds to the ECB:
                     *
                     *  (a)   There is no speculative tracing (which can effectively
                     *        cache an EPID for an arbitrary amount of time).
                     *
                     *  (b)   The principal buffers have been switched twice since the
                     *        provider became defunct.
                     *
                     *  (c)   The aggregation buffers are of zero size or have been
                     *        switched twice since the provider became defunct.
                     *
                     * We use dts_speculates to determine (a) and call a function
                     * (dtrace_buffer_consumed()) to determine (b) and (c).  Note
                     * that as soon as we've been unable to destroy one of the ECBs
                     * associated with the probe, we quit trying -- reaping is only
                     * fruitful in as much as we can destroy all ECBs associated
                     * with the defunct provider's probes.
                     */
                    while ((ecb = probe->dtpr_ecb) != NULL) {
                              dtrace_state_t *state = ecb->dte_state;
                              dtrace_buffer_t *buf = state->dts_buffer;
                              dtrace_buffer_t *aggbuf = state->dts_aggbuffer;

                              if (state->dts_speculates)
                                        break;

                              if (!dtrace_buffer_consumed(buf, when))
                                        break;

                              if (!dtrace_buffer_consumed(aggbuf, when))
                                        break;

                              dtrace_ecb_disable(ecb);
                              ASSERT(probe->dtpr_ecb != ecb);
                              dtrace_ecb_destroy(ecb);
                    }
          }

          mutex_exit(&dtrace_lock);
          mutex_exit(&cpu_lock);
}
/*
 * DTrace DOF Functions
 */
/*ARGSUSED*/
static void
dtrace_dof_error(dof_hdr_t *dof, const char *str)
{
          if (dtrace_err_verbose)
                    cmn_err(CE_WARN, "failed to process DOF: %s", str);

#ifdef DTRACE_ERRDEBUG
          dtrace_errdebug(str);
#endif
}

/*
 * Create DOF out of a currently enabled state.  Right now, we only create
 * DOF containing the run-time options -- but this could be expanded to create
 * complete DOF representing the enabled state.
 */
static dof_hdr_t *
dtrace_dof_create(dtrace_state_t *state)
{
          dof_hdr_t *dof;
          dof_sec_t *sec;
          dof_optdesc_t *opt;
          int i, len = sizeof (dof_hdr_t) +
              roundup(sizeof (dof_sec_t), sizeof (uint64_t)) +
              sizeof (dof_optdesc_t) * DTRACEOPT_MAX;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          dof = kmem_zalloc(len, KM_SLEEP);
          dof->dofh_ident[DOF_ID_MAG0] = DOF_MAG_MAG0;
          dof->dofh_ident[DOF_ID_MAG1] = DOF_MAG_MAG1;
          dof->dofh_ident[DOF_ID_MAG2] = DOF_MAG_MAG2;
          dof->dofh_ident[DOF_ID_MAG3] = DOF_MAG_MAG3;

          dof->dofh_ident[DOF_ID_MODEL] = DOF_MODEL_NATIVE;
          dof->dofh_ident[DOF_ID_ENCODING] = DOF_ENCODE_NATIVE;
          dof->dofh_ident[DOF_ID_VERSION] = DOF_VERSION;
          dof->dofh_ident[DOF_ID_DIFVERS] = DIF_VERSION;
          dof->dofh_ident[DOF_ID_DIFIREG] = DIF_DIR_NREGS;
          dof->dofh_ident[DOF_ID_DIFTREG] = DIF_DTR_NREGS;

          dof->dofh_flags = 0;
          dof->dofh_hdrsize = sizeof (dof_hdr_t);
          dof->dofh_secsize = sizeof (dof_sec_t);
          dof->dofh_secnum = 1;         /* only DOF_SECT_OPTDESC */
          dof->dofh_secoff = sizeof (dof_hdr_t);
          dof->dofh_loadsz = len;
          dof->dofh_filesz = len;
          dof->dofh_pad = 0;

          /*
           * Fill in the option section header...
           */
          sec = (dof_sec_t *)((uintptr_t)dof + sizeof (dof_hdr_t));
          sec->dofs_type = DOF_SECT_OPTDESC;
          sec->dofs_align = sizeof (uint64_t);
          sec->dofs_flags = DOF_SECF_LOAD;
          sec->dofs_entsize = sizeof (dof_optdesc_t);

          opt = (dof_optdesc_t *)((uintptr_t)sec +
              roundup(sizeof (dof_sec_t), sizeof (uint64_t)));

          sec->dofs_offset = (uintptr_t)opt - (uintptr_t)dof;
          sec->dofs_size = sizeof (dof_optdesc_t) * DTRACEOPT_MAX;

          for (i = 0; i < DTRACEOPT_MAX; i++) {
                    opt[i].dofo_option = i;
                    opt[i].dofo_strtab = DOF_SECIDX_NONE;
                    opt[i].dofo_value = state->dts_options[i];
          }

          return (dof);
}

static dof_hdr_t *
dtrace_dof_copyin(uintptr_t uarg, int *errp)
{
          dof_hdr_t hdr, *dof;

          ASSERT(!MUTEX_HELD(&dtrace_lock));

          /*
           * First, we're going to copyin() the sizeof (dof_hdr_t).
           */
          if (copyin((void *)uarg, &hdr, sizeof (hdr)) != 0) {
                    dtrace_dof_error(NULL, "failed to copyin DOF header");
                    *errp = EFAULT;
                    return (NULL);
          }

          /*
           * Now we'll allocate the entire DOF and copy it in -- provided
           * that the length isn't outrageous.
           */
          if (hdr.dofh_loadsz >= dtrace_dof_maxsize) {
                    dtrace_dof_error(&hdr, "load size exceeds maximum");
                    *errp = E2BIG;
                    return (NULL);
          }

          if (hdr.dofh_loadsz < sizeof (hdr)) {
                    dtrace_dof_error(&hdr, "invalid load size");
                    *errp = EINVAL;
                    return (NULL);
          }

          dof = kmem_alloc(hdr.dofh_loadsz, KM_SLEEP);

          if (copyin((void *)uarg, dof, hdr.dofh_loadsz) != 0 ||
              dof->dofh_loadsz != hdr.dofh_loadsz) {
                    kmem_free(dof, hdr.dofh_loadsz);
                    *errp = EFAULT;
                    return (NULL);
          }

          return (dof);
}

#ifdef __FreeBSD__
static dof_hdr_t *
dtrace_dof_copyin_proc(struct proc *p, uintptr_t uarg, int *errp)
{
          dof_hdr_t hdr, *dof;
          struct thread *td;
          size_t loadsz;

          ASSERT(!MUTEX_HELD(&dtrace_lock));

          td = curthread;

          /*
           * First, we're going to copyin() the sizeof (dof_hdr_t).
           */
          if (proc_readmem(td, p, uarg, &hdr, sizeof(hdr)) != sizeof(hdr)) {
                    dtrace_dof_error(NULL, "failed to copyin DOF header");
                    *errp = EFAULT;
                    return (NULL);
          }

          /*
           * Now we'll allocate the entire DOF and copy it in -- provided
           * that the length isn't outrageous.
           */
          if (hdr.dofh_loadsz >= dtrace_dof_maxsize) {
                    dtrace_dof_error(&hdr, "load size exceeds maximum");
                    *errp = E2BIG;
                    return (NULL);
          }
          loadsz = (size_t)hdr.dofh_loadsz;

          if (loadsz < sizeof (hdr)) {
                    dtrace_dof_error(&hdr, "invalid load size");
                    *errp = EINVAL;
                    return (NULL);
          }

          dof = kmem_alloc(loadsz, KM_SLEEP);

          if (proc_readmem(td, p, uarg, dof, loadsz) != loadsz ||
              dof->dofh_loadsz != loadsz) {
                    kmem_free(dof, hdr.dofh_loadsz);
                    *errp = EFAULT;
                    return (NULL);
          }

          return (dof);
}
#endif /* __FreeBSD__ */
#ifdef __NetBSD__
static dof_hdr_t *
dtrace_dof_copyin_pid(pid_t pid, const void *uarg, int *errp)
{
          dof_hdr_t hdr, *dof;
          size_t loadsz;
          int err;

          err = copyin_pid(pid, uarg, &hdr, sizeof(hdr));
          if (err != 0) {
                    *errp = err;
                    return (NULL);
          }

          /*
           * Now we'll allocate the entire DOF and copy it in -- provided
           * that the length isn't outrageous.
           */
          if (hdr.dofh_loadsz >= dtrace_dof_maxsize) {
                    dtrace_dof_error(&hdr, "load size exceeds maximum");
                    *errp = E2BIG;
                    return (NULL);
          }
          loadsz = (size_t)hdr.dofh_loadsz;

          if (loadsz < sizeof (hdr)) {
                    dtrace_dof_error(&hdr, "invalid load size");
                    *errp = EINVAL;
                    return (NULL);
          }

          dof = kmem_alloc(loadsz, KM_SLEEP);

          err = copyin_pid(pid, uarg, dof, loadsz);
          if (err == 0 && dof->dofh_loadsz != loadsz)
                    err = EFAULT;
          if (err != 0) {
                    kmem_free(dof, loadsz);
                    *errp = EFAULT;
                    return (NULL);
          }

          return (dof);
}
#endif

#ifdef __FreeBSD__
static __inline uchar_t
dtrace_dof_char(char c)
{

          switch (c) {
          case '0':
          case '1':
          case '2':
          case '3':
          case '4':
          case '5':
          case '6':
          case '7':
          case '8':
          case '9':
                    return (c - '0');
          case 'A':
          case 'B':
          case 'C':
          case 'D':
          case 'E':
          case 'F':
                    return (c - 'A' + 10);
          case 'a':
          case 'b':
          case 'c':
          case 'd':
          case 'e':
          case 'f':
                    return (c - 'a' + 10);
          }
          /* Should not reach here. */
          return (UCHAR_MAX);
}
#endif /* __FreeBSD__ */

static dof_hdr_t *
dtrace_dof_property(const char *name)
{
#ifdef illumos
          uchar_t *buf;
          uint64_t loadsz;
          unsigned int len, i;
          dof_hdr_t *dof = NULL;

          /*
           * Unfortunately, array of values in .conf files are always (and
           * only) interpreted to be integer arrays.  We must read our DOF
           * as an integer array, and then squeeze it into a byte array.
           */
          if (ddi_prop_lookup_int_array(DDI_DEV_T_ANY, dtrace_devi, 0,
              (char *)name, (int **)&buf, &len) != DDI_PROP_SUCCESS)
                    return (NULL);

          for (i = 0; i < len; i++)
                    buf[i] = (uchar_t)(((int *)buf)[i]);

          if (len < sizeof (dof_hdr_t)) {
                    ddi_prop_free(buf);
                    dtrace_dof_error(NULL, "truncated header");
                    return (NULL);
          }

          if (len < (loadsz = ((dof_hdr_t *)buf)->dofh_loadsz)) {
                    ddi_prop_free(buf);
                    dtrace_dof_error(NULL, "truncated DOF");
                    return (NULL);
          }

          if (loadsz >= dtrace_dof_maxsize) {
                    ddi_prop_free(buf);
                    dtrace_dof_error(NULL, "oversized DOF");
                    return (NULL);
          }

          dof = kmem_alloc(loadsz, KM_SLEEP);
          bcopy(buf, dof, loadsz);
          ddi_prop_free(buf);

          return (dof);
#endif /* illumos */
#ifdef __FreeBSD__
          uint8_t *dofbuf;
          u_char *data, *eol;
          caddr_t doffile;
          size_t bytes, len, i;
          dof_hdr_t *dof;
          u_char c1, c2;

          dof = NULL;

          doffile = preload_search_by_type("dtrace_dof");
          if (doffile == NULL)
                    return (NULL);

          data = preload_fetch_addr(doffile);
          len = preload_fetch_size(doffile);
          for (;;) {
                    /* Look for the end of the line. All lines end in a newline. */
                    eol = memchr(data, '\n', len);
                    if (eol == NULL)
                              return (NULL);

                    if (strncmp(name, data, strlen(name)) == 0)
                              break;

                    eol++; /* skip past the newline */
                    len -= eol - data;
                    data = eol;
          }

          /* We've found the data corresponding to the specified key. */

          data += strlen(name) + 1; /* skip past the '=' */
          len = eol - data;
          if (len % 2 != 0) {
                    dtrace_dof_error(NULL, "invalid DOF encoding length");
                    goto doferr;
          }
          bytes = len / 2;
          if (bytes < sizeof(dof_hdr_t)) {
                    dtrace_dof_error(NULL, "truncated header");
                    goto doferr;
          }

          /*
           * Each byte is represented by the two ASCII characters in its hex
           * representation.
           */
          dofbuf = malloc(bytes, M_SOLARIS, M_WAITOK);
          for (i = 0; i < bytes; i++) {
                    c1 = dtrace_dof_char(data[i * 2]);
                    c2 = dtrace_dof_char(data[i * 2 + 1]);
                    if (c1 == UCHAR_MAX || c2 == UCHAR_MAX) {
                              dtrace_dof_error(NULL, "invalid hex char in DOF");
                              goto doferr;
                    }
                    dofbuf[i] = c1 * 16 + c2;
          }

          dof = (dof_hdr_t *)dofbuf;
          if (bytes < dof->dofh_loadsz) {
                    dtrace_dof_error(NULL, "truncated DOF");
                    goto doferr;
          }

          if (dof->dofh_loadsz >= dtrace_dof_maxsize) {
                    dtrace_dof_error(NULL, "oversized DOF");
                    goto doferr;
          }

          return (dof);

doferr:
          free(dof, M_SOLARIS);
          return (NULL);
#endif /* __FreeBSD__ */
#ifdef __NetBSD__
          return (NULL);
#endif /* __NetBSD__ */
}

static void
dtrace_dof_destroy(dof_hdr_t *dof)
{
          kmem_free(dof, dof->dofh_loadsz);
}

/*
 * Return the dof_sec_t pointer corresponding to a given section index.  If the
 * index is not valid, dtrace_dof_error() is called and NULL is returned.  If
 * a type other than DOF_SECT_NONE is specified, the header is checked against
 * this type and NULL is returned if the types do not match.
 */
static dof_sec_t *
dtrace_dof_sect(dof_hdr_t *dof, uint32_t type, dof_secidx_t i)
{
          dof_sec_t *sec = (dof_sec_t *)(uintptr_t)
              ((uintptr_t)dof + dof->dofh_secoff + i * dof->dofh_secsize);

          if (i >= dof->dofh_secnum) {
                    dtrace_dof_error(dof, "referenced section index is invalid");
                    return (NULL);
          }

          if (!(sec->dofs_flags & DOF_SECF_LOAD)) {
                    dtrace_dof_error(dof, "referenced section is not loadable");
                    return (NULL);
          }

          if (type != DOF_SECT_NONE && type != sec->dofs_type) {
                    dtrace_dof_error(dof, "referenced section is the wrong type");
                    return (NULL);
          }

          return (sec);
}

static dtrace_probedesc_t *
dtrace_dof_probedesc(dof_hdr_t *dof, dof_sec_t *sec, dtrace_probedesc_t *desc)
{
          dof_probedesc_t *probe;
          dof_sec_t *strtab;
          uintptr_t daddr = (uintptr_t)dof;
          uintptr_t str;
          size_t size;

          if (sec->dofs_type != DOF_SECT_PROBEDESC) {
                    dtrace_dof_error(dof, "invalid probe section");
                    return (NULL);
          }

          if (sec->dofs_align != sizeof (dof_secidx_t)) {
                    dtrace_dof_error(dof, "bad alignment in probe description");
                    return (NULL);
          }

          if (sec->dofs_offset + sizeof (dof_probedesc_t) > dof->dofh_loadsz) {
                    dtrace_dof_error(dof, "truncated probe description");
                    return (NULL);
          }

          probe = (dof_probedesc_t *)(uintptr_t)(daddr + sec->dofs_offset);
          strtab = dtrace_dof_sect(dof, DOF_SECT_STRTAB, probe->dofp_strtab);

          if (strtab == NULL)
                    return (NULL);

          str = daddr + strtab->dofs_offset;
          size = strtab->dofs_size;

          if (probe->dofp_provider >= strtab->dofs_size) {
                    dtrace_dof_error(dof, "corrupt probe provider");
                    return (NULL);
          }

          (void) strncpy(desc->dtpd_provider,
              (char *)(str + probe->dofp_provider),
              MIN(DTRACE_PROVNAMELEN - 1, size - probe->dofp_provider));

          if (probe->dofp_mod >= strtab->dofs_size) {
                    dtrace_dof_error(dof, "corrupt probe module");
                    return (NULL);
          }

          (void) strncpy(desc->dtpd_mod, (char *)(str + probe->dofp_mod),
              MIN(DTRACE_MODNAMELEN - 1, size - probe->dofp_mod));

          if (probe->dofp_func >= strtab->dofs_size) {
                    dtrace_dof_error(dof, "corrupt probe function");
                    return (NULL);
          }

          (void) strncpy(desc->dtpd_func, (char *)(str + probe->dofp_func),
              MIN(DTRACE_FUNCNAMELEN - 1, size - probe->dofp_func));

          if (probe->dofp_name >= strtab->dofs_size) {
                    dtrace_dof_error(dof, "corrupt probe name");
                    return (NULL);
          }

          (void) strncpy(desc->dtpd_name, (char *)(str + probe->dofp_name),
              MIN(DTRACE_NAMELEN - 1, size - probe->dofp_name));

          return (desc);
}

static dtrace_difo_t *
dtrace_dof_difo(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
    cred_t *cr)
{
          dtrace_difo_t *dp;
          size_t ttl = 0;
          dof_difohdr_t *dofd;
          uintptr_t daddr = (uintptr_t)dof;
          size_t max = dtrace_difo_maxsize;
          int i, l, n;

          static const struct {
                    int section;
                    int bufoffs;
                    int lenoffs;
                    int entsize;
                    int align;
                    const char *msg;
          } difo[] = {
                    { DOF_SECT_DIF, offsetof(dtrace_difo_t, dtdo_buf),
                    offsetof(dtrace_difo_t, dtdo_len), sizeof (dif_instr_t),
                    sizeof (dif_instr_t), "multiple DIF sections" },

                    { DOF_SECT_INTTAB, offsetof(dtrace_difo_t, dtdo_inttab),
                    offsetof(dtrace_difo_t, dtdo_intlen), sizeof (uint64_t),
                    sizeof (uint64_t), "multiple integer tables" },

                    { DOF_SECT_STRTAB, offsetof(dtrace_difo_t, dtdo_strtab),
                    offsetof(dtrace_difo_t, dtdo_strlen), 0,
                    sizeof (char), "multiple string tables" },

                    { DOF_SECT_VARTAB, offsetof(dtrace_difo_t, dtdo_vartab),
                    offsetof(dtrace_difo_t, dtdo_varlen), sizeof (dtrace_difv_t),
                    sizeof (uint_t), "multiple variable tables" },

                    { DOF_SECT_NONE, 0, 0, 0, 0, NULL }
          };

          if (sec->dofs_type != DOF_SECT_DIFOHDR) {
                    dtrace_dof_error(dof, "invalid DIFO header section");
                    return (NULL);
          }

          if (sec->dofs_align != sizeof (dof_secidx_t)) {
                    dtrace_dof_error(dof, "bad alignment in DIFO header");
                    return (NULL);
          }

          if (sec->dofs_size < sizeof (dof_difohdr_t) ||
              sec->dofs_size % sizeof (dof_secidx_t)) {
                    dtrace_dof_error(dof, "bad size in DIFO header");
                    return (NULL);
          }

          dofd = (dof_difohdr_t *)(uintptr_t)(daddr + sec->dofs_offset);
          n = (sec->dofs_size - sizeof (*dofd)) / sizeof (dof_secidx_t) + 1;

          dp = kmem_zalloc(sizeof (dtrace_difo_t), KM_SLEEP);
          dp->dtdo_rtype = dofd->dofd_rtype;

          for (l = 0; l < n; l++) {
                    dof_sec_t *subsec;
                    void **bufp;
                    uint32_t *lenp;

                    if ((subsec = dtrace_dof_sect(dof, DOF_SECT_NONE,
                        dofd->dofd_links[l])) == NULL)
                              goto err; /* invalid section link */

                    if (ttl + subsec->dofs_size > max) {
                              dtrace_dof_error(dof, "exceeds maximum size");
                              goto err;
                    }

                    ttl += subsec->dofs_size;

                    for (i = 0; difo[i].section != DOF_SECT_NONE; i++) {
                              if (subsec->dofs_type != difo[i].section)
                                        continue;

                              if (!(subsec->dofs_flags & DOF_SECF_LOAD)) {
                                        dtrace_dof_error(dof, "section not loaded");
                                        goto err;
                              }

                              if (subsec->dofs_align != difo[i].align) {
                                        dtrace_dof_error(dof, "bad alignment");
                                        goto err;
                              }

                              bufp = (void **)((uintptr_t)dp + difo[i].bufoffs);
                              lenp = (uint32_t *)((uintptr_t)dp + difo[i].lenoffs);

                              if (*bufp != NULL) {
                                        dtrace_dof_error(dof, difo[i].msg);
                                        goto err;
                              }

                              if (difo[i].entsize != subsec->dofs_entsize) {
                                        dtrace_dof_error(dof, "entry size mismatch");
                                        goto err;
                              }

                              if (subsec->dofs_entsize != 0 &&
                                  (subsec->dofs_size % subsec->dofs_entsize) != 0) {
                                        dtrace_dof_error(dof, "corrupt entry size");
                                        goto err;
                              }

                              *lenp = subsec->dofs_size;
                              *bufp = kmem_alloc(subsec->dofs_size, KM_SLEEP);
                              bcopy((char *)(uintptr_t)(daddr + subsec->dofs_offset),
                                  *bufp, subsec->dofs_size);

                              if (subsec->dofs_entsize != 0)
                                        *lenp /= subsec->dofs_entsize;

                              break;
                    }

                    /*
                     * If we encounter a loadable DIFO sub-section that is not
                     * known to us, assume this is a broken program and fail.
                     */
                    if (difo[i].section == DOF_SECT_NONE &&
                        (subsec->dofs_flags & DOF_SECF_LOAD)) {
                              dtrace_dof_error(dof, "unrecognized DIFO subsection");
                              goto err;
                    }
          }

          if (dp->dtdo_buf == NULL) {
                    /*
                     * We can't have a DIF object without DIF text.
                     */
                    dtrace_dof_error(dof, "missing DIF text");
                    goto err;
          }

          /*
           * Before we validate the DIF object, run through the variable table
           * looking for the strings -- if any of their size are under, we'll set
           * their size to be the system-wide default string size.  Note that
           * this should _not_ happen if the "strsize" option has been set --
           * in this case, the compiler should have set the size to reflect the
           * setting of the option.
           */
          for (i = 0; i < dp->dtdo_varlen; i++) {
                    dtrace_difv_t *v = &dp->dtdo_vartab[i];
                    dtrace_diftype_t *t = &v->dtdv_type;

                    if (v->dtdv_id < DIF_VAR_OTHER_UBASE)
                              continue;

                    if (t->dtdt_kind == DIF_TYPE_STRING && t->dtdt_size == 0)
                              t->dtdt_size = dtrace_strsize_default;
          }

          if (dtrace_difo_validate(dp, vstate, DIF_DIR_NREGS, cr) != 0)
                    goto err;

          dtrace_difo_init(dp, vstate);
          return (dp);

err:
          kmem_free(dp->dtdo_buf, dp->dtdo_len * sizeof (dif_instr_t));
          kmem_free(dp->dtdo_inttab, dp->dtdo_intlen * sizeof (uint64_t));
          kmem_free(dp->dtdo_strtab, dp->dtdo_strlen);
          kmem_free(dp->dtdo_vartab, dp->dtdo_varlen * sizeof (dtrace_difv_t));

          kmem_free(dp, sizeof (dtrace_difo_t));
          return (NULL);
}

static dtrace_predicate_t *
dtrace_dof_predicate(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
    cred_t *cr)
{
          dtrace_difo_t *dp;

          if ((dp = dtrace_dof_difo(dof, sec, vstate, cr)) == NULL)
                    return (NULL);

          return (dtrace_predicate_create(dp));
}

static dtrace_actdesc_t *
dtrace_dof_actdesc(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
    cred_t *cr)
{
          dtrace_actdesc_t *act, *first = NULL, *last = NULL, *next;
          dof_actdesc_t *desc;
          dof_sec_t *difosec;
          size_t offs;
          uintptr_t daddr = (uintptr_t)dof;
          uint64_t arg;
          dtrace_actkind_t kind;

          if (sec->dofs_type != DOF_SECT_ACTDESC) {
                    dtrace_dof_error(dof, "invalid action section");
                    return (NULL);
          }

          if (sec->dofs_offset + sizeof (dof_actdesc_t) > dof->dofh_loadsz) {
                    dtrace_dof_error(dof, "truncated action description");
                    return (NULL);
          }

          if (sec->dofs_align != sizeof (uint64_t)) {
                    dtrace_dof_error(dof, "bad alignment in action description");
                    return (NULL);
          }

          if (sec->dofs_size < sec->dofs_entsize) {
                    dtrace_dof_error(dof, "section entry size exceeds total size");
                    return (NULL);
          }

          if (sec->dofs_entsize != sizeof (dof_actdesc_t)) {
                    dtrace_dof_error(dof, "bad entry size in action description");
                    return (NULL);
          }

          if (sec->dofs_size / sec->dofs_entsize > dtrace_actions_max) {
                    dtrace_dof_error(dof, "actions exceed dtrace_actions_max");
                    return (NULL);
          }

          for (offs = 0; offs < sec->dofs_size; offs += sec->dofs_entsize) {
                    desc = (dof_actdesc_t *)(daddr +
                        (uintptr_t)sec->dofs_offset + offs);
                    kind = (dtrace_actkind_t)desc->dofa_kind;

                    if ((DTRACEACT_ISPRINTFLIKE(kind) &&
                        (kind != DTRACEACT_PRINTA ||
                        desc->dofa_strtab != DOF_SECIDX_NONE)) ||
                        (kind == DTRACEACT_DIFEXPR &&
                        desc->dofa_strtab != DOF_SECIDX_NONE)) {
                              dof_sec_t *strtab;
                              char *str, *fmt;
                              uint64_t i;

                              /*
                               * The argument to these actions is an index into the
                               * DOF string table.  For printf()-like actions, this
                               * is the format string.  For print(), this is the
                               * CTF type of the expression result.
                               */
                              if ((strtab = dtrace_dof_sect(dof,
                                  DOF_SECT_STRTAB, desc->dofa_strtab)) == NULL)
                                        goto err;

                              str = (char *)((uintptr_t)dof +
                                  (uintptr_t)strtab->dofs_offset);

                              for (i = desc->dofa_arg; i < strtab->dofs_size; i++) {
                                        if (str[i] == '\0')
                                                  break;
                              }

                              if (i >= strtab->dofs_size) {
                                        dtrace_dof_error(dof, "bogus format string");
                                        goto err;
                              }

                              if (i == desc->dofa_arg) {
                                        dtrace_dof_error(dof, "empty format string");
                                        goto err;
                              }

                              i -= desc->dofa_arg;
                              fmt = kmem_alloc(i + 1, KM_SLEEP);
                              bcopy(&str[desc->dofa_arg], fmt, i + 1);
                              arg = (uint64_t)(uintptr_t)fmt;
                    } else {
                              if (kind == DTRACEACT_PRINTA) {
                                        ASSERT(desc->dofa_strtab == DOF_SECIDX_NONE);
                                        arg = 0;
                              } else {
                                        arg = desc->dofa_arg;
                              }
                    }

                    act = dtrace_actdesc_create(kind, desc->dofa_ntuple,
                        desc->dofa_uarg, arg);

                    if (last != NULL) {
                              last->dtad_next = act;
                    } else {
                              first = act;
                    }

                    last = act;

                    if (desc->dofa_difo == DOF_SECIDX_NONE)
                              continue;

                    if ((difosec = dtrace_dof_sect(dof,
                        DOF_SECT_DIFOHDR, desc->dofa_difo)) == NULL)
                              goto err;

                    act->dtad_difo = dtrace_dof_difo(dof, difosec, vstate, cr);

                    if (act->dtad_difo == NULL)
                              goto err;
          }

          ASSERT(first != NULL);
          return (first);

err:
          for (act = first; act != NULL; act = next) {
                    next = act->dtad_next;
                    dtrace_actdesc_release(act, vstate);
          }

          return (NULL);
}

static dtrace_ecbdesc_t *
dtrace_dof_ecbdesc(dof_hdr_t *dof, dof_sec_t *sec, dtrace_vstate_t *vstate,
    cred_t *cr)
{
          dtrace_ecbdesc_t *ep;
          dof_ecbdesc_t *ecb;
          dtrace_probedesc_t *desc;
          dtrace_predicate_t *pred = NULL;

          if (sec->dofs_size < sizeof (dof_ecbdesc_t)) {
                    dtrace_dof_error(dof, "truncated ECB description");
                    return (NULL);
          }

          if (sec->dofs_align != sizeof (uint64_t)) {
                    dtrace_dof_error(dof, "bad alignment in ECB description");
                    return (NULL);
          }

          ecb = (dof_ecbdesc_t *)((uintptr_t)dof + (uintptr_t)sec->dofs_offset);
          sec = dtrace_dof_sect(dof, DOF_SECT_PROBEDESC, ecb->dofe_probes);

          if (sec == NULL)
                    return (NULL);

          ep = kmem_zalloc(sizeof (dtrace_ecbdesc_t), KM_SLEEP);
          ep->dted_uarg = ecb->dofe_uarg;
          desc = &ep->dted_probe;

          if (dtrace_dof_probedesc(dof, sec, desc) == NULL)
                    goto err;

          if (ecb->dofe_pred != DOF_SECIDX_NONE) {
                    if ((sec = dtrace_dof_sect(dof,
                        DOF_SECT_DIFOHDR, ecb->dofe_pred)) == NULL)
                              goto err;

                    if ((pred = dtrace_dof_predicate(dof, sec, vstate, cr)) == NULL)
                              goto err;

                    ep->dted_pred.dtpdd_predicate = pred;
          }

          if (ecb->dofe_actions != DOF_SECIDX_NONE) {
                    if ((sec = dtrace_dof_sect(dof,
                        DOF_SECT_ACTDESC, ecb->dofe_actions)) == NULL)
                              goto err;

                    ep->dted_action = dtrace_dof_actdesc(dof, sec, vstate, cr);

                    if (ep->dted_action == NULL)
                              goto err;
          }

          return (ep);

err:
          if (pred != NULL)
                    dtrace_predicate_release(pred, vstate);
          kmem_free(ep, sizeof (dtrace_ecbdesc_t));
          return (NULL);
}

/*
 * Apply the relocations from the specified 'sec' (a DOF_SECT_URELHDR) to the
 * specified DOF.  SETX relocations are computed using 'ubase', the base load
 * address of the object containing the DOF, and DOFREL relocations are relative
 * to the relocation offset within the DOF.
 */
static int
dtrace_dof_relocate(dof_hdr_t *dof, dof_sec_t *sec, uint64_t ubase,
    uint64_t udaddr)
{
          uintptr_t daddr = (uintptr_t)dof;
          dof_relohdr_t *dofr =
              (dof_relohdr_t *)(uintptr_t)(daddr + sec->dofs_offset);
          dof_sec_t *ss, *rs, *ts;
          dof_relodesc_t *r;
          uint_t i, n;

          if (sec->dofs_size < sizeof (dof_relohdr_t) ||
              sec->dofs_align != sizeof (dof_secidx_t)) {
                    dtrace_dof_error(dof, "invalid relocation header");
                    return (-1);
          }

          ss = dtrace_dof_sect(dof, DOF_SECT_STRTAB, dofr->dofr_strtab);
          rs = dtrace_dof_sect(dof, DOF_SECT_RELTAB, dofr->dofr_relsec);
          ts = dtrace_dof_sect(dof, DOF_SECT_NONE, dofr->dofr_tgtsec);

          if (ss == NULL || rs == NULL || ts == NULL)
                    return (-1); /* dtrace_dof_error() has been called already */

          if (rs->dofs_entsize < sizeof (dof_relodesc_t) ||
              rs->dofs_align != sizeof (uint64_t)) {
                    dtrace_dof_error(dof, "invalid relocation section");
                    return (-1);
          }

          r = (dof_relodesc_t *)(uintptr_t)(daddr + rs->dofs_offset);
          n = rs->dofs_size / rs->dofs_entsize;

          for (i = 0; i < n; i++) {
                    uintptr_t taddr = daddr + ts->dofs_offset + r->dofr_offset;

                    switch (r->dofr_type) {
                    case DOF_RELO_NONE:
                              break;
                    case DOF_RELO_SETX:
                    case DOF_RELO_DOFREL:
                              if (r->dofr_offset >= ts->dofs_size || r->dofr_offset +
                                  sizeof (uint64_t) > ts->dofs_size) {
                                        dtrace_dof_error(dof, "bad relocation offset");
                                        return (-1);
                              }

                              if (!IS_P2ALIGNED(taddr, sizeof (uint64_t))) {
                                        dtrace_dof_error(dof, "misaligned setx relo");
                                        return (-1);
                              }

                              if (r->dofr_type == DOF_RELO_SETX)
                                        *(uint64_t *)taddr += ubase;
                              else
                                        *(uint64_t *)taddr +=
                                            udaddr + ts->dofs_offset + r->dofr_offset;
                              break;
                    default:
                              dtrace_dof_error(dof, "invalid relocation type");
                              return (-1);
                    }

                    r = (dof_relodesc_t *)((uintptr_t)r + rs->dofs_entsize);
          }

          return (0);
}

/*
 * The dof_hdr_t passed to dtrace_dof_slurp() should be a partially validated
 * header:  it should be at the front of a memory region that is at least
 * sizeof (dof_hdr_t) in size -- and then at least dof_hdr.dofh_loadsz in
 * size.  It need not be validated in any other way.
 */
static int
dtrace_dof_slurp(dof_hdr_t *dof, dtrace_vstate_t *vstate, cred_t *cr,
    dtrace_enabling_t **enabp, uint64_t ubase, uint64_t udaddr, int noprobes)
{
          uint64_t len = dof->dofh_loadsz, seclen;
          uintptr_t daddr = (uintptr_t)dof;
          dtrace_ecbdesc_t *ep;
          dtrace_enabling_t *enab;
          uint_t i;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(dof->dofh_loadsz >= sizeof (dof_hdr_t));

          /*
           * Check the DOF header identification bytes.  In addition to checking
           * valid settings, we also verify that unused bits/bytes are zeroed so
           * we can use them later without fear of regressing existing binaries.
           */
          if (bcmp(&dof->dofh_ident[DOF_ID_MAG0],
              DOF_MAG_STRING, DOF_MAG_STRLEN) != 0) {
                    dtrace_dof_error(dof, "DOF magic string mismatch");
                    return (-1);
          }

          if (dof->dofh_ident[DOF_ID_MODEL] != DOF_MODEL_ILP32 &&
              dof->dofh_ident[DOF_ID_MODEL] != DOF_MODEL_LP64) {
                    dtrace_dof_error(dof, "DOF has invalid data model");
                    return (-1);
          }

          if (dof->dofh_ident[DOF_ID_ENCODING] != DOF_ENCODE_NATIVE) {
                    dtrace_dof_error(dof, "DOF encoding mismatch");
                    return (-1);
          }

          if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1 &&
              dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_2) {
                    dtrace_dof_error(dof, "DOF version mismatch");
                    return (-1);
          }

          if (dof->dofh_ident[DOF_ID_DIFVERS] != DIF_VERSION_2) {
                    dtrace_dof_error(dof, "DOF uses unsupported instruction set");
                    return (-1);
          }

          if (dof->dofh_ident[DOF_ID_DIFIREG] > DIF_DIR_NREGS) {
                    dtrace_dof_error(dof, "DOF uses too many integer registers");
                    return (-1);
          }

          if (dof->dofh_ident[DOF_ID_DIFTREG] > DIF_DTR_NREGS) {
                    dtrace_dof_error(dof, "DOF uses too many tuple registers");
                    return (-1);
          }

          for (i = DOF_ID_PAD; i < DOF_ID_SIZE; i++) {
                    if (dof->dofh_ident[i] != 0) {
                              dtrace_dof_error(dof, "DOF has invalid ident byte set");
                              return (-1);
                    }
          }

          if (dof->dofh_flags & ~DOF_FL_VALID) {
                    dtrace_dof_error(dof, "DOF has invalid flag bits set");
                    return (-1);
          }

          if (dof->dofh_secsize == 0) {
                    dtrace_dof_error(dof, "zero section header size");
                    return (-1);
          }

          /*
           * Check that the section headers don't exceed the amount of DOF
           * data.  Note that we cast the section size and number of sections
           * to uint64_t's to prevent possible overflow in the multiplication.
           */
          seclen = (uint64_t)dof->dofh_secnum * (uint64_t)dof->dofh_secsize;

          if (dof->dofh_secoff > len || seclen > len ||
              dof->dofh_secoff + seclen > len) {
                    dtrace_dof_error(dof, "truncated section headers");
                    return (-1);
          }

          if (!IS_P2ALIGNED(dof->dofh_secoff, sizeof (uint64_t))) {
                    dtrace_dof_error(dof, "misaligned section headers");
                    return (-1);
          }

          if (!IS_P2ALIGNED(dof->dofh_secsize, sizeof (uint64_t))) {
                    dtrace_dof_error(dof, "misaligned section size");
                    return (-1);
          }

          /*
           * Take an initial pass through the section headers to be sure that
           * the headers don't have stray offsets.  If the 'noprobes' flag is
           * set, do not permit sections relating to providers, probes, or args.
           */
          for (i = 0; i < dof->dofh_secnum; i++) {
                    dof_sec_t *sec = (dof_sec_t *)(daddr +
                        (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);

                    if (noprobes) {
                              switch (sec->dofs_type) {
                              case DOF_SECT_PROVIDER:
                              case DOF_SECT_PROBES:
                              case DOF_SECT_PRARGS:
                              case DOF_SECT_PROFFS:
                                        dtrace_dof_error(dof, "illegal sections "
                                            "for enabling");
                                        return (-1);
                              }
                    }

                    if (DOF_SEC_ISLOADABLE(sec->dofs_type) &&
                        !(sec->dofs_flags & DOF_SECF_LOAD)) {
                              dtrace_dof_error(dof, "loadable section with load "
                                  "flag unset");
                              return (-1);
                    }

                    if (!(sec->dofs_flags & DOF_SECF_LOAD))
                              continue; /* just ignore non-loadable sections */

                    if (!ISP2(sec->dofs_align)) {
                              dtrace_dof_error(dof, "bad section alignment");
                              return (-1);
                    }

                    if (sec->dofs_offset & (sec->dofs_align - 1)) {
                              dtrace_dof_error(dof, "misaligned section");
                              return (-1);
                    }

                    if (sec->dofs_offset > len || sec->dofs_size > len ||
                        sec->dofs_offset + sec->dofs_size > len) {
                              dtrace_dof_error(dof, "corrupt section header");
                              return (-1);
                    }

                    if (sec->dofs_type == DOF_SECT_STRTAB && *((char *)daddr +
                        sec->dofs_offset + sec->dofs_size - 1) != '\0') {
                              dtrace_dof_error(dof, "non-terminating string table");
                              return (-1);
                    }
          }

          /*
           * Take a second pass through the sections and locate and perform any
           * relocations that are present.  We do this after the first pass to
           * be sure that all sections have had their headers validated.
           */
          for (i = 0; i < dof->dofh_secnum; i++) {
                    dof_sec_t *sec = (dof_sec_t *)(daddr +
                        (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);

                    if (!(sec->dofs_flags & DOF_SECF_LOAD))
                              continue; /* skip sections that are not loadable */

                    switch (sec->dofs_type) {
                    case DOF_SECT_URELHDR:
                              if (dtrace_dof_relocate(dof, sec, ubase, udaddr) != 0)
                                        return (-1);
                              break;
                    }
          }

          if ((enab = *enabp) == NULL)
                    enab = *enabp = dtrace_enabling_create(vstate);

          for (i = 0; i < dof->dofh_secnum; i++) {
                    dof_sec_t *sec = (dof_sec_t *)(daddr +
                        (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);

                    if (sec->dofs_type != DOF_SECT_ECBDESC)
                              continue;

                    if ((ep = dtrace_dof_ecbdesc(dof, sec, vstate, cr)) == NULL) {
                              dtrace_enabling_destroy(enab);
                              *enabp = NULL;
                              return (-1);
                    }

                    dtrace_enabling_add(enab, ep);
          }

          return (0);
}

/*
 * Process DOF for any options.  This routine assumes that the DOF has been
 * at least processed by dtrace_dof_slurp().
 */
static int
dtrace_dof_options(dof_hdr_t *dof, dtrace_state_t *state)
{
          int i, rval;
          uint32_t entsize;
          size_t offs;
          dof_optdesc_t *desc;

          for (i = 0; i < dof->dofh_secnum; i++) {
                    dof_sec_t *sec = (dof_sec_t *)((uintptr_t)dof +
                        (uintptr_t)dof->dofh_secoff + i * dof->dofh_secsize);

                    if (sec->dofs_type != DOF_SECT_OPTDESC)
                              continue;

                    if (sec->dofs_align != sizeof (uint64_t)) {
                              dtrace_dof_error(dof, "bad alignment in "
                                  "option description");
                              return (EINVAL);
                    }

                    if ((entsize = sec->dofs_entsize) == 0) {
                              dtrace_dof_error(dof, "zeroed option entry size");
                              return (EINVAL);
                    }

                    if (entsize < sizeof (dof_optdesc_t)) {
                              dtrace_dof_error(dof, "bad option entry size");
                              return (EINVAL);
                    }

                    for (offs = 0; offs < sec->dofs_size; offs += entsize) {
                              desc = (dof_optdesc_t *)((uintptr_t)dof +
                                  (uintptr_t)sec->dofs_offset + offs);

                              if (desc->dofo_strtab != DOF_SECIDX_NONE) {
                                        dtrace_dof_error(dof, "non-zero option string");
                                        return (EINVAL);
                              }

                              if (desc->dofo_value == DTRACEOPT_UNSET) {
                                        dtrace_dof_error(dof, "unset option");
                                        return (EINVAL);
                              }

                              if ((rval = dtrace_state_option(state,
                                  desc->dofo_option, desc->dofo_value)) != 0) {
                                        dtrace_dof_error(dof, "rejected option");
                                        return (rval);
                              }
                    }
          }

          return (0);
}

/*
 * DTrace Consumer State Functions
 */
static int
dtrace_dstate_init(dtrace_dstate_t *dstate, size_t size)
{
          size_t hashsize, maxper, min, chunksize = dstate->dtds_chunksize;
          void *base;
          uintptr_t limit;
          dtrace_dynvar_t *dvar, *next, *start;
          int i;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(dstate->dtds_base == NULL && dstate->dtds_percpu == NULL);

          bzero(dstate, sizeof (dtrace_dstate_t));

          if ((dstate->dtds_chunksize = chunksize) == 0)
                    dstate->dtds_chunksize = DTRACE_DYNVAR_CHUNKSIZE;

          VERIFY(dstate->dtds_chunksize < LONG_MAX);

          if (size < (min = dstate->dtds_chunksize + sizeof (dtrace_dynhash_t)))
                    size = min;

          if ((base = kmem_zalloc(size, KM_NOSLEEP | KM_NORMALPRI)) == NULL)
                    return (ENOMEM);

          dstate->dtds_size = size;
          dstate->dtds_base = base;
          dstate->dtds_percpu = kmem_cache_alloc(dtrace_state_cache, KM_SLEEP);
          bzero(dstate->dtds_percpu, NCPU * sizeof (dtrace_dstate_percpu_t));

          hashsize = size / (dstate->dtds_chunksize + sizeof (dtrace_dynhash_t));

          if (hashsize != 1 && (hashsize & 1))
                    hashsize--;

          dstate->dtds_hashsize = hashsize;
          dstate->dtds_hash = dstate->dtds_base;

          /*
           * Set all of our hash buckets to point to the single sink, and (if
           * it hasn't already been set), set the sink's hash value to be the
           * sink sentinel value.  The sink is needed for dynamic variable
           * lookups to know that they have iterated over an entire, valid hash
           * chain.
           */
          for (i = 0; i < hashsize; i++)
                    dstate->dtds_hash[i].dtdh_chain = &dtrace_dynhash_sink;

          if (dtrace_dynhash_sink.dtdv_hashval != DTRACE_DYNHASH_SINK)
                    dtrace_dynhash_sink.dtdv_hashval = DTRACE_DYNHASH_SINK;

          /*
           * Determine number of active CPUs.  Divide free list evenly among
           * active CPUs.
           */
          start = (dtrace_dynvar_t *)
              ((uintptr_t)base + hashsize * sizeof (dtrace_dynhash_t));
          limit = (uintptr_t)base + size;

          VERIFY((uintptr_t)start < limit);
          VERIFY((uintptr_t)start >= (uintptr_t)base);

          maxper = (limit - (uintptr_t)start) / NCPU;
          maxper = (maxper / dstate->dtds_chunksize) * dstate->dtds_chunksize;

#ifdef illumos
          for (i = 0; i < NCPU; i++)
#endif
#ifdef __FreeBSD__
          CPU_FOREACH(i)
#endif
#ifdef __NetBSD__
          for (i = 0; i < NCPU; i++)
#endif
          {
                    dstate->dtds_percpu[i].dtdsc_free = dvar = start;

                    /*
                     * If we don't even have enough chunks to make it once through
                     * NCPUs, we're just going to allocate everything to the first
                     * CPU.  And if we're on the last CPU, we're going to allocate
                     * whatever is left over.  In either case, we set the limit to
                     * be the limit of the dynamic variable space.
                     */
                    if (maxper == 0 || i == NCPU - 1) {
                              limit = (uintptr_t)base + size;
                              start = NULL;
                    } else {
                              limit = (uintptr_t)start + maxper;
                              start = (dtrace_dynvar_t *)limit;
                    }

                    VERIFY(limit <= (uintptr_t)base + size);

                    for (;;) {
                              next = (dtrace_dynvar_t *)((uintptr_t)dvar +
                                  dstate->dtds_chunksize);

                              if ((uintptr_t)next + dstate->dtds_chunksize >= limit)
                                        break;

                              VERIFY((uintptr_t)dvar >= (uintptr_t)base &&
                                  (uintptr_t)dvar <= (uintptr_t)base + size);
                              dvar->dtdv_next = next;
                              dvar = next;
                    }

                    if (maxper == 0)
                              break;
          }

          return (0);
}

static void
dtrace_dstate_fini(dtrace_dstate_t *dstate)
{
          ASSERT(MUTEX_HELD(&cpu_lock));

          if (dstate->dtds_base == NULL)
                    return;

          kmem_free(dstate->dtds_base, dstate->dtds_size);
          kmem_cache_free(dtrace_state_cache, dstate->dtds_percpu);
}

static void
dtrace_vstate_fini(dtrace_vstate_t *vstate)
{
          /*
           * Logical XOR, where are you?
           */
          ASSERT((vstate->dtvs_nglobals == 0) ^ (vstate->dtvs_globals != NULL));

          if (vstate->dtvs_nglobals > 0) {
                    kmem_free(vstate->dtvs_globals, vstate->dtvs_nglobals *
                        sizeof (dtrace_statvar_t *));
          }

          if (vstate->dtvs_ntlocals > 0) {
                    kmem_free(vstate->dtvs_tlocals, vstate->dtvs_ntlocals *
                        sizeof (dtrace_difv_t));
          }

          ASSERT((vstate->dtvs_nlocals == 0) ^ (vstate->dtvs_locals != NULL));

          if (vstate->dtvs_nlocals > 0) {
                    kmem_free(vstate->dtvs_locals, vstate->dtvs_nlocals *
                        sizeof (dtrace_statvar_t *));
          }
}

#ifdef __FreeBSD__
static void
dtrace_state_clean(void *arg)
{
          dtrace_state_t *state = arg;
          dtrace_optval_t *opt = state->dts_options;

          if (state->dts_activity == DTRACE_ACTIVITY_INACTIVE)
                    return;

          dtrace_dynvar_clean(&state->dts_vstate.dtvs_dynvars);
          dtrace_speculation_clean(state);

          callout_reset(&state->dts_cleaner, hz * opt[DTRACEOPT_CLEANRATE] / NANOSEC,
              dtrace_state_clean, state);
}

static void
dtrace_state_deadman(void *arg)
{
          dtrace_state_t *state = arg;
          hrtime_t now;

          dtrace_sync();

          dtrace_debug_output();

          now = dtrace_gethrtime();

          if (state != dtrace_anon.dta_state &&
              now - state->dts_laststatus >= dtrace_deadman_user)
                    return;

          /*
           * We must be sure that dts_alive never appears to be less than the
           * value upon entry to dtrace_state_deadman(), and because we lack a
           * dtrace_cas64(), we cannot store to it atomically.  We thus instead
           * store INT64_MAX to it, followed by a memory barrier, followed by
           * the new value.  This assures that dts_alive never appears to be
           * less than its true value, regardless of the order in which the
           * stores to the underlying storage are issued.
           */
          state->dts_alive = INT64_MAX;
          dtrace_membar_producer();
          state->dts_alive = now;

          callout_reset(&state->dts_deadman, hz * dtrace_deadman_interval / NANOSEC,
              dtrace_state_deadman, state);
}
#else
static void
dtrace_state_clean(dtrace_state_t *state)
{
          if (state->dts_activity == DTRACE_ACTIVITY_INACTIVE)
                    return;

          dtrace_dynvar_clean(&state->dts_vstate.dtvs_dynvars);
          dtrace_speculation_clean(state);
}

static void
dtrace_state_deadman(dtrace_state_t *state)
{
          hrtime_t now;

          dtrace_sync();

          now = dtrace_gethrtime();

          if (state != dtrace_anon.dta_state &&
              now - state->dts_laststatus >= dtrace_deadman_user)
                    return;

          /*
           * We must be sure that dts_alive never appears to be less than the
           * value upon entry to dtrace_state_deadman(), and because we lack a
           * dtrace_cas64(), we cannot store to it atomically.  We thus instead
           * store INT64_MAX to it, followed by a memory barrier, followed by
           * the new value.  This assures that dts_alive never appears to be
           * less than its true value, regardless of the order in which the
           * stores to the underlying storage are issued.
           */
          state->dts_alive = INT64_MAX;
          dtrace_membar_producer();
          state->dts_alive = now;
}

#endif    /* illumos */

static dtrace_state_t *
#ifdef illumos
dtrace_state_create(dev_t *devp, cred_t *cr)
#endif
#ifdef __FreeBSD__
dtrace_state_create(struct cdev *dev, struct ucred *cred __unused)
#endif
#ifdef __NetBSD__
dtrace_state_create(dev_t *devp, cred_t *cr)
#endif
{
#ifdef illumos
          minor_t minor;
          major_t major;
#else
          int m = 0;
#endif
#ifdef __FreeBSD__
          cred_t *cr = NULL;
#endif
          int cpu_it;
          char c[30];
          dtrace_state_t *state;
          dtrace_optval_t *opt;
          int bufsize = NCPU * sizeof (dtrace_buffer_t), i;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(MUTEX_HELD(&cpu_lock));

#ifdef illumos
          minor = (minor_t)(uintptr_t)vmem_alloc(dtrace_minor, 1,
              VM_BESTFIT | VM_SLEEP);

          if (ddi_soft_state_zalloc(dtrace_softstate, minor) != DDI_SUCCESS) {
                    vmem_free(dtrace_minor, (void *)(uintptr_t)minor, 1);
                    return (NULL);
          }

          state = ddi_get_soft_state(dtrace_softstate, minor);
#endif
#ifdef __FreeBSD__
          if (dev != NULL) {
                    cr = dev->si_cred;
                    m = dev2unit(dev);
          }
#endif
#ifdef __NetBSD__
          m = minor(*devp) & 0x0F;

          /* Allocate memory for the state. */
          state = kmem_zalloc(sizeof(dtrace_state_t), KM_SLEEP);
#endif


          state->dts_epid = DTRACE_EPIDNONE + 1;

          (void) snprintf(c, sizeof (c), "dtrace_aggid_%d", m);
#ifdef illumos
          state->dts_aggid_arena = vmem_create(c, (void *)1, UINT32_MAX, 1,
              NULL, NULL, NULL, 0, VM_SLEEP | VMC_IDENTIFIER);

          if (devp != NULL) {
                    major = getemajor(*devp);
          } else {
                    major = ddi_driver_major(dtrace_devi);
          }

          state->dts_dev = makedevice(major, minor);

          if (devp != NULL)
                    *devp = state->dts_dev;
#endif
#ifdef __FreeBSD__
          state->dts_aggid_arena = new_unrhdr(1, INT_MAX, &dtrace_unr_mtx);
          state->dts_dev = dev;
#endif
#ifdef __NetBSD__
          state->dts_aggid_arena = vmem_create(c, 1, INT_MAX, 1,
              NULL, NULL, NULL, 0, VM_SLEEP, IPL_NONE);
          state->dts_dev = *devp;
#endif

          /*
           * We allocate NCPU buffers.  On the one hand, this can be quite
           * a bit of memory per instance (nearly 36K on a Starcat).  On the
           * other hand, it saves an additional memory reference in the probe
           * path.
           */
          state->dts_buffer = kmem_zalloc(bufsize, KM_SLEEP);
          state->dts_aggbuffer = kmem_zalloc(bufsize, KM_SLEEP);

          /*
         * Allocate and initialise the per-process per-CPU random state.
           * SI_SUB_RANDOM < SI_SUB_DTRACE_ANON therefore entropy device is
         * assumed to be seeded at this point (if from Fortuna seed file).
           */
          (void) read_random(&state->dts_rstate[0], 2 * sizeof(uint64_t));
          for (cpu_it = 1; cpu_it < NCPU; cpu_it++) {
                    /*
                     * Each CPU is assigned a 2^64 period, non-overlapping
                     * subsequence.
                     */
                    dtrace_xoroshiro128_plus_jump(state->dts_rstate[cpu_it-1],
                        state->dts_rstate[cpu_it]);
          }


#ifdef illumos
          state->dts_cleaner = CYCLIC_NONE;
          state->dts_deadman = CYCLIC_NONE;
#endif
#ifdef __FreeBSD__
          callout_init(&state->dts_cleaner, 1);
          callout_init(&state->dts_deadman, 1);
#endif
#ifdef __NetBSD__
          state->dts_cleaner = NULL;
          state->dts_deadman = NULL;
#endif
          state->dts_vstate.dtvs_state = state;

          for (i = 0; i < DTRACEOPT_MAX; i++)
                    state->dts_options[i] = DTRACEOPT_UNSET;

          /*
           * Set the default options.
           */
          opt = state->dts_options;
          opt[DTRACEOPT_BUFPOLICY] = DTRACEOPT_BUFPOLICY_SWITCH;
          opt[DTRACEOPT_BUFRESIZE] = DTRACEOPT_BUFRESIZE_AUTO;
          opt[DTRACEOPT_NSPEC] = dtrace_nspec_default;
          opt[DTRACEOPT_SPECSIZE] = dtrace_specsize_default;
          opt[DTRACEOPT_CPU] = (dtrace_optval_t)DTRACE_CPUALL;
          opt[DTRACEOPT_STRSIZE] = dtrace_strsize_default;
          opt[DTRACEOPT_STACKFRAMES] = dtrace_stackframes_default;
          opt[DTRACEOPT_USTACKFRAMES] = dtrace_ustackframes_default;
          opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_default;
          opt[DTRACEOPT_AGGRATE] = dtrace_aggrate_default;
          opt[DTRACEOPT_SWITCHRATE] = dtrace_switchrate_default;
          opt[DTRACEOPT_STATUSRATE] = dtrace_statusrate_default;
          opt[DTRACEOPT_JSTACKFRAMES] = dtrace_jstackframes_default;
          opt[DTRACEOPT_JSTACKSTRSIZE] = dtrace_jstackstrsize_default;

          state->dts_activity = DTRACE_ACTIVITY_INACTIVE;

          /*
           * Depending on the user credentials, we set flag bits which alter probe
           * visibility or the amount of destructiveness allowed.  In the case of
           * actual anonymous tracing, or the possession of all privileges, all of
           * the normal checks are bypassed.
           */
          if (cr == NULL || PRIV_POLICY_ONLY(cr, PRIV_ALL, B_FALSE)) {
                    state->dts_cred.dcr_visible = DTRACE_CRV_ALL;
                    state->dts_cred.dcr_action = DTRACE_CRA_ALL;
          } else {
                    /*
                     * Set up the credentials for this instantiation.  We take a
                     * hold on the credential to prevent it from disappearing on
                     * us; this in turn prevents the zone_t referenced by this
                     * credential from disappearing.  This means that we can
                     * examine the credential and the zone from probe context.
                     */
                    crhold(cr);
                    state->dts_cred.dcr_cred = cr;

                    /*
                     * CRA_PROC means "we have *some* privilege for dtrace" and
                     * unlocks the use of variables like pid, zonename, etc.
                     */
                    if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_USER, B_FALSE) ||
                        PRIV_POLICY_ONLY(cr, PRIV_DTRACE_PROC, B_FALSE)) {
                              state->dts_cred.dcr_action |= DTRACE_CRA_PROC;
                    }

                    /*
                     * dtrace_user allows use of syscall and profile providers.
                     * If the user also has proc_owner and/or proc_zone, we
                     * extend the scope to include additional visibility and
                     * destructive power.
                     */
                    if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_USER, B_FALSE)) {
                              if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE)) {
                                        state->dts_cred.dcr_visible |=
                                            DTRACE_CRV_ALLPROC;

                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER;
                              }

                              if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE)) {
                                        state->dts_cred.dcr_visible |=
                                            DTRACE_CRV_ALLZONE;

                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE;
                              }

                              /*
                               * If we have all privs in whatever zone this is,
                               * we can do destructive things to processes which
                               * have altered credentials.
                               */
#ifdef illumos
                              if (priv_isequalset(priv_getset(cr, PRIV_EFFECTIVE),
                                  cr->cr_zone->zone_privset)) {
                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG;
                              }
#endif
                    }

                    /*
                     * Holding the dtrace_kernel privilege also implies that
                     * the user has the dtrace_user privilege from a visibility
                     * perspective.  But without further privileges, some
                     * destructive actions are not available.
                     */
                    if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_KERNEL, B_FALSE)) {
                              /*
                               * Make all probes in all zones visible.  However,
                               * this doesn't mean that all actions become available
                               * to all zones.
                               */
                              state->dts_cred.dcr_visible |= DTRACE_CRV_KERNEL |
                                  DTRACE_CRV_ALLPROC | DTRACE_CRV_ALLZONE;

                              state->dts_cred.dcr_action |= DTRACE_CRA_KERNEL |
                                  DTRACE_CRA_PROC;
                              /*
                               * Holding proc_owner means that destructive actions
                               * for *this* zone are allowed.
                               */
                              if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE))
                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER;

                              /*
                               * Holding proc_zone means that destructive actions
                               * for this user/group ID in all zones is allowed.
                               */
                              if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE))
                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE;

#ifdef illumos
                              /*
                               * If we have all privs in whatever zone this is,
                               * we can do destructive things to processes which
                               * have altered credentials.
                               */
                              if (priv_isequalset(priv_getset(cr, PRIV_EFFECTIVE),
                                  cr->cr_zone->zone_privset)) {
                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_CREDCHG;
                              }
#endif
                    }

                    /*
                     * Holding the dtrace_proc privilege gives control over fasttrap
                     * and pid providers.  We need to grant wider destructive
                     * privileges in the event that the user has proc_owner and/or
                     * proc_zone.
                     */
                    if (PRIV_POLICY_ONLY(cr, PRIV_DTRACE_PROC, B_FALSE)) {
                              if (PRIV_POLICY_ONLY(cr, PRIV_PROC_OWNER, B_FALSE))
                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_ALLUSER;

                              if (PRIV_POLICY_ONLY(cr, PRIV_PROC_ZONE, B_FALSE))
                                        state->dts_cred.dcr_action |=
                                            DTRACE_CRA_PROC_DESTRUCTIVE_ALLZONE;
                    }
          }

          return (state);
}

static int
dtrace_state_buffer(dtrace_state_t *state, dtrace_buffer_t *buf, int which)
{
          dtrace_optval_t *opt = state->dts_options, size;
          processorid_t cpu = 0;;
          int flags = 0, rval, factor, divisor = 1;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(MUTEX_HELD(&cpu_lock));
          ASSERT(which < DTRACEOPT_MAX);
          ASSERT(state->dts_activity == DTRACE_ACTIVITY_INACTIVE ||
              (state == dtrace_anon.dta_state &&
              state->dts_activity == DTRACE_ACTIVITY_ACTIVE));

          if (opt[which] == DTRACEOPT_UNSET || opt[which] == 0)
                    return (0);

          if (opt[DTRACEOPT_CPU] != DTRACEOPT_UNSET)
                    cpu = opt[DTRACEOPT_CPU];

          if (which == DTRACEOPT_SPECSIZE)
                    flags |= DTRACEBUF_NOSWITCH;

          if (which == DTRACEOPT_BUFSIZE) {
                    if (opt[DTRACEOPT_BUFPOLICY] == DTRACEOPT_BUFPOLICY_RING)
                              flags |= DTRACEBUF_RING;

                    if (opt[DTRACEOPT_BUFPOLICY] == DTRACEOPT_BUFPOLICY_FILL)
                              flags |= DTRACEBUF_FILL;

                    if (state != dtrace_anon.dta_state ||
                        state->dts_activity != DTRACE_ACTIVITY_ACTIVE)
                              flags |= DTRACEBUF_INACTIVE;
          }

          for (size = opt[which]; size >= sizeof (uint64_t); size /= divisor) {
                    /*
                     * The size must be 8-byte aligned.  If the size is not 8-byte
                     * aligned, drop it down by the difference.
                     */
                    if (size & (sizeof (uint64_t) - 1))
                              size -= size & (sizeof (uint64_t) - 1);

                    if (size < state->dts_reserve) {
                              /*
                               * Buffers always must be large enough to accommodate
                               * their prereserved space.  We return E2BIG instead
                               * of ENOMEM in this case to allow for user-level
                               * software to differentiate the cases.
                               */
                              return (E2BIG);
                    }

                    rval = dtrace_buffer_alloc(buf, size, flags, cpu, &factor);

                    if (rval != ENOMEM) {
                              opt[which] = size;
                              return (rval);
                    }

                    if (opt[DTRACEOPT_BUFRESIZE] == DTRACEOPT_BUFRESIZE_MANUAL)
                              return (rval);

                    for (divisor = 2; divisor < factor; divisor <<= 1)
                              continue;
          }

          return (ENOMEM);
}

static int
dtrace_state_buffers(dtrace_state_t *state)
{
          dtrace_speculation_t *spec = state->dts_speculations;
          int rval, i;

          if ((rval = dtrace_state_buffer(state, state->dts_buffer,
              DTRACEOPT_BUFSIZE)) != 0)
                    return (rval);

          if ((rval = dtrace_state_buffer(state, state->dts_aggbuffer,
              DTRACEOPT_AGGSIZE)) != 0)
                    return (rval);

          for (i = 0; i < state->dts_nspeculations; i++) {
                    if ((rval = dtrace_state_buffer(state,
                        spec[i].dtsp_buffer, DTRACEOPT_SPECSIZE)) != 0)
                              return (rval);
          }

          return (0);
}

static void
dtrace_state_prereserve(dtrace_state_t *state)
{
          dtrace_ecb_t *ecb;
          dtrace_probe_t *probe;

          state->dts_reserve = 0;

          if (state->dts_options[DTRACEOPT_BUFPOLICY] != DTRACEOPT_BUFPOLICY_FILL)
                    return;

          /*
           * If our buffer policy is a "fill" buffer policy, we need to set the
           * prereserved space to be the space required by the END probes.
           */
          probe = dtrace_probes[dtrace_probeid_end - 1];
          ASSERT(probe != NULL);

          for (ecb = probe->dtpr_ecb; ecb != NULL; ecb = ecb->dte_next) {
                    if (ecb->dte_state != state)
                              continue;

                    state->dts_reserve += ecb->dte_needed + ecb->dte_alignment;
          }
}

static int
dtrace_state_go(dtrace_state_t *state, processorid_t *cpu)
{
          dtrace_optval_t *opt = state->dts_options, sz, nspec;
          dtrace_speculation_t *spec;
          dtrace_buffer_t *buf;
#ifdef illumos
          cyc_handler_t hdlr;
          cyc_time_t when;
#endif
          int rval = 0, i, bufsize = NCPU * sizeof (dtrace_buffer_t);
          dtrace_icookie_t cookie;

          mutex_enter(&cpu_lock);
          mutex_enter(&dtrace_lock);

          if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE) {
                    rval = EBUSY;
                    goto out;
          }

          /*
           * Before we can perform any checks, we must prime all of the
           * retained enablings that correspond to this state.
           */
          dtrace_enabling_prime(state);

          if (state->dts_destructive && !state->dts_cred.dcr_destructive) {
                    rval = EACCES;
                    goto out;
          }

          dtrace_state_prereserve(state);

          /*
           * Now we want to do is try to allocate our speculations.
           * We do not automatically resize the number of speculations; if
           * this fails, we will fail the operation.
           */
          nspec = opt[DTRACEOPT_NSPEC];
          ASSERT(nspec != DTRACEOPT_UNSET);

          if (nspec > INT_MAX) {
                    rval = ENOMEM;
                    goto out;
          }

          spec = kmem_zalloc(nspec * sizeof (dtrace_speculation_t),
              KM_NOSLEEP | KM_NORMALPRI);

          if (spec == NULL) {
                    rval = ENOMEM;
                    goto out;
          }

          state->dts_speculations = spec;
          state->dts_nspeculations = (int)nspec;

          for (i = 0; i < nspec; i++) {
                    if ((buf = kmem_zalloc(bufsize,
                        KM_NOSLEEP | KM_NORMALPRI)) == NULL) {
                              rval = ENOMEM;
                              goto err;
                    }

                    spec[i].dtsp_buffer = buf;
          }

          if (opt[DTRACEOPT_GRABANON] != DTRACEOPT_UNSET) {
                    if (dtrace_anon.dta_state == NULL) {
                              rval = ENOENT;
                              goto out;
                    }

                    if (state->dts_necbs != 0) {
                              rval = EALREADY;
                              goto out;
                    }

                    state->dts_anon = dtrace_anon_grab();
                    ASSERT(state->dts_anon != NULL);
                    state = state->dts_anon;

                    /*
                     * We want "grabanon" to be set in the grabbed state, so we'll
                     * copy that option value from the grabbing state into the
                     * grabbed state.
                     */
                    state->dts_options[DTRACEOPT_GRABANON] =
                        opt[DTRACEOPT_GRABANON];

                    *cpu = dtrace_anon.dta_beganon;

                    /*
                     * If the anonymous state is active (as it almost certainly
                     * is if the anonymous enabling ultimately matched anything),
                     * we don't allow any further option processing -- but we
                     * don't return failure.
                     */
                    if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE)
                              goto out;
          }

          if (opt[DTRACEOPT_AGGSIZE] != DTRACEOPT_UNSET &&
              opt[DTRACEOPT_AGGSIZE] != 0) {
                    if (state->dts_aggregations == NULL) {
                              /*
                               * We're not going to create an aggregation buffer
                               * because we don't have any ECBs that contain
                               * aggregations -- set this option to 0.
                               */
                              opt[DTRACEOPT_AGGSIZE] = 0;
                    } else {
                              /*
                               * If we have an aggregation buffer, we must also have
                               * a buffer to use as scratch.
                               */
                              if (opt[DTRACEOPT_BUFSIZE] == DTRACEOPT_UNSET ||
                                  opt[DTRACEOPT_BUFSIZE] < state->dts_needed) {
                                        opt[DTRACEOPT_BUFSIZE] = state->dts_needed;
                              }
                    }
          }

          if (opt[DTRACEOPT_SPECSIZE] != DTRACEOPT_UNSET &&
              opt[DTRACEOPT_SPECSIZE] != 0) {
                    if (!state->dts_speculates) {
                              /*
                               * We're not going to create speculation buffers
                               * because we don't have any ECBs that actually
                               * speculate -- set the speculation size to 0.
                               */
                              opt[DTRACEOPT_SPECSIZE] = 0;
                    }
          }

          /*
           * The bare minimum size for any buffer that we're actually going to
           * do anything to is sizeof (uint64_t).
           */
          sz = sizeof (uint64_t);

          if ((state->dts_needed != 0 && opt[DTRACEOPT_BUFSIZE] < sz) ||
              (state->dts_speculates && opt[DTRACEOPT_SPECSIZE] < sz) ||
              (state->dts_aggregations != NULL && opt[DTRACEOPT_AGGSIZE] < sz)) {
                    /*
                     * A buffer size has been explicitly set to 0 (or to a size
                     * that will be adjusted to 0) and we need the space -- we
                     * need to return failure.  We return ENOSPC to differentiate
                     * it from failing to allocate a buffer due to failure to meet
                     * the reserve (for which we return E2BIG).
                     */
                    rval = ENOSPC;
                    goto out;
          }

          if ((rval = dtrace_state_buffers(state)) != 0)
                    goto err;

          if ((sz = opt[DTRACEOPT_DYNVARSIZE]) == DTRACEOPT_UNSET)
                    sz = dtrace_dstate_defsize;

          do {
                    rval = dtrace_dstate_init(&state->dts_vstate.dtvs_dynvars, sz);

                    if (rval == 0)
                              break;

                    if (opt[DTRACEOPT_BUFRESIZE] == DTRACEOPT_BUFRESIZE_MANUAL)
                              goto err;
          } while (sz >>= 1);

          opt[DTRACEOPT_DYNVARSIZE] = sz;

          if (rval != 0)
                    goto err;

          if (opt[DTRACEOPT_STATUSRATE] > dtrace_statusrate_max)
                    opt[DTRACEOPT_STATUSRATE] = dtrace_statusrate_max;

          if (opt[DTRACEOPT_CLEANRATE] == 0)
                    opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_max;

          if (opt[DTRACEOPT_CLEANRATE] < dtrace_cleanrate_min)
                    opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_min;

          if (opt[DTRACEOPT_CLEANRATE] > dtrace_cleanrate_max)
                    opt[DTRACEOPT_CLEANRATE] = dtrace_cleanrate_max;

          state->dts_alive = state->dts_laststatus = dtrace_gethrtime();
#ifdef illumos
          hdlr.cyh_func = (cyc_func_t)dtrace_state_clean;
          hdlr.cyh_arg = state;
          hdlr.cyh_level = CY_LOW_LEVEL;

          when.cyt_when = 0;
          when.cyt_interval = opt[DTRACEOPT_CLEANRATE];

          state->dts_cleaner = cyclic_add(&hdlr, &when);

          hdlr.cyh_func = (cyc_func_t)dtrace_state_deadman;
          hdlr.cyh_arg = state;
          hdlr.cyh_level = CY_LOW_LEVEL;

          when.cyt_when = 0;
          when.cyt_interval = dtrace_deadman_interval;

          state->dts_deadman = cyclic_add(&hdlr, &when);
#endif
#ifdef __FreeBSD__
          callout_reset(&state->dts_cleaner, hz * opt[DTRACEOPT_CLEANRATE] / NANOSEC,
              dtrace_state_clean, state);
          callout_reset(&state->dts_deadman, hz * dtrace_deadman_interval / NANOSEC,
              dtrace_state_deadman, state);
#endif
#ifdef __NetBSD__
          state->dts_cleaner = dtrace_state_worker_add(
              dtrace_state_clean, state, opt[DTRACEOPT_CLEANRATE]);
          state->dts_deadman = dtrace_state_worker_add(
              dtrace_state_deadman, state, dtrace_deadman_interval);
#endif

          state->dts_activity = DTRACE_ACTIVITY_WARMUP;

#ifdef illumos
          if (state->dts_getf != 0 &&
              !(state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL)) {
                    /*
                     * We don't have kernel privs but we have at least one call
                     * to getf(); we need to bump our zone's count, and (if
                     * this is the first enabling to have an unprivileged call
                     * to getf()) we need to hook into closef().
                     */
                    state->dts_cred.dcr_cred->cr_zone->zone_dtrace_getf++;

                    if (dtrace_getf++ == 0) {
                              ASSERT(dtrace_closef == NULL);
                              dtrace_closef = dtrace_getf_barrier;
                    }
          }
#endif

          /*
           * Now it's time to actually fire the BEGIN probe.  We need to disable
           * interrupts here both to record the CPU on which we fired the BEGIN
           * probe (the data from this CPU will be processed first at user
           * level) and to manually activate the buffer for this CPU.
           */
          cookie = dtrace_interrupt_disable();
          *cpu = curcpu_id;
          ASSERT(state->dts_buffer[*cpu].dtb_flags & DTRACEBUF_INACTIVE);
          state->dts_buffer[*cpu].dtb_flags &= ~DTRACEBUF_INACTIVE;

          dtrace_probe(dtrace_probeid_begin,
              (uint64_t)(uintptr_t)state, 0, 0, 0, 0);
          dtrace_interrupt_enable(cookie);
          /*
           * We may have had an exit action from a BEGIN probe; only change our
           * state to ACTIVE if we're still in WARMUP.
           */
          ASSERT(state->dts_activity == DTRACE_ACTIVITY_WARMUP ||
              state->dts_activity == DTRACE_ACTIVITY_DRAINING);

          if (state->dts_activity == DTRACE_ACTIVITY_WARMUP)
                    state->dts_activity = DTRACE_ACTIVITY_ACTIVE;

#ifdef __FreeBSD__
          /*
           * We enable anonymous tracing before APs are started, so we must
           * activate buffers using the current CPU.
           */
          if (state == dtrace_anon.dta_state)
                    for (int i = 0; i < NCPU; i++)
                              dtrace_buffer_activate_cpu(state, i);
          else
                    dtrace_xcall(DTRACE_CPUALL,
                        (dtrace_xcall_t)dtrace_buffer_activate, state);
#else

          /*
           * Regardless of whether or not now we're in ACTIVE or DRAINING, we
           * want each CPU to transition its principal buffer out of the
           * INACTIVE state.  Doing this assures that no CPU will suddenly begin
           * processing an ECB halfway down a probe's ECB chain; all CPUs will
           * atomically transition from processing none of a state's ECBs to
           * processing all of them.
           */
          dtrace_xcall(DTRACE_CPUALL,
              (dtrace_xcall_t)dtrace_buffer_activate, state);
#endif
          goto out;

err:
          dtrace_buffer_free(state->dts_buffer);
          dtrace_buffer_free(state->dts_aggbuffer);

          if ((nspec = state->dts_nspeculations) == 0) {
                    ASSERT(state->dts_speculations == NULL);
                    goto out;
          }

          spec = state->dts_speculations;
          ASSERT(spec != NULL);

          for (i = 0; i < state->dts_nspeculations; i++) {
                    if ((buf = spec[i].dtsp_buffer) == NULL)
                              break;

                    dtrace_buffer_free(buf);
                    kmem_free(buf, bufsize);
          }

          kmem_free(spec, nspec * sizeof (dtrace_speculation_t));
          state->dts_nspeculations = 0;
          state->dts_speculations = NULL;

out:
          mutex_exit(&dtrace_lock);
          mutex_exit(&cpu_lock);

          return (rval);
}

static int
dtrace_state_stop(dtrace_state_t *state, processorid_t *cpu)
{
          dtrace_icookie_t cookie;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (state->dts_activity != DTRACE_ACTIVITY_ACTIVE &&
              state->dts_activity != DTRACE_ACTIVITY_DRAINING)
                    return (EINVAL);

          /*
           * We'll set the activity to DTRACE_ACTIVITY_DRAINING, and issue a sync
           * to be sure that every CPU has seen it.  See below for the details
           * on why this is done.
           */
          state->dts_activity = DTRACE_ACTIVITY_DRAINING;
          dtrace_sync();

          /*
           * By this point, it is impossible for any CPU to be still processing
           * with DTRACE_ACTIVITY_ACTIVE.  We can thus set our activity to
           * DTRACE_ACTIVITY_COOLDOWN and know that we're not racing with any
           * other CPU in dtrace_buffer_reserve().  This allows dtrace_probe()
           * and callees to know that the activity is DTRACE_ACTIVITY_COOLDOWN
           * iff we're in the END probe.
           */
          state->dts_activity = DTRACE_ACTIVITY_COOLDOWN;
          dtrace_sync();
          ASSERT(state->dts_activity == DTRACE_ACTIVITY_COOLDOWN);

          /*
           * Finally, we can release the reserve and call the END probe.  We
           * disable interrupts across calling the END probe to allow us to
           * return the CPU on which we actually called the END probe.  This
           * allows user-land to be sure that this CPU's principal buffer is
           * processed last.
           */
          state->dts_reserve = 0;

          cookie = dtrace_interrupt_disable();
          *cpu = curcpu_id;
          dtrace_probe(dtrace_probeid_end,
              (uint64_t)(uintptr_t)state, 0, 0, 0, 0);
          dtrace_interrupt_enable(cookie);

          state->dts_activity = DTRACE_ACTIVITY_STOPPED;
          dtrace_sync();

#ifdef illumos
          if (state->dts_getf != 0 &&
              !(state->dts_cred.dcr_visible & DTRACE_CRV_KERNEL)) {
                    /*
                     * We don't have kernel privs but we have at least one call
                     * to getf(); we need to lower our zone's count, and (if
                     * this is the last enabling to have an unprivileged call
                     * to getf()) we need to clear the closef() hook.
                     */
                    ASSERT(state->dts_cred.dcr_cred->cr_zone->zone_dtrace_getf > 0);
                    ASSERT(dtrace_closef == dtrace_getf_barrier);
                    ASSERT(dtrace_getf > 0);

                    state->dts_cred.dcr_cred->cr_zone->zone_dtrace_getf--;

                    if (--dtrace_getf == 0)
                              dtrace_closef = NULL;
          }
#endif

          return (0);
}

static int
dtrace_state_option(dtrace_state_t *state, dtrace_optid_t option,
    dtrace_optval_t val)
{
          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE)
                    return (EBUSY);

          if (option >= DTRACEOPT_MAX)
                    return (EINVAL);

          if (option != DTRACEOPT_CPU && val < 0)
                    return (EINVAL);

          switch (option) {
          case DTRACEOPT_DESTRUCTIVE:
                    if (dtrace_destructive_disallow)
                              return (EACCES);

                    state->dts_cred.dcr_destructive = 1;
                    break;

          case DTRACEOPT_BUFSIZE:
          case DTRACEOPT_DYNVARSIZE:
          case DTRACEOPT_AGGSIZE:
          case DTRACEOPT_SPECSIZE:
          case DTRACEOPT_STRSIZE:
                    if (val < 0)
                              return (EINVAL);

                    if (val >= LONG_MAX) {
                              /*
                               * If this is an otherwise negative value, set it to
                               * the highest multiple of 128m less than LONG_MAX.
                               * Technically, we're adjusting the size without
                               * regard to the buffer resizing policy, but in fact,
                               * this has no effect -- if we set the buffer size to
                               * ~LONG_MAX and the buffer policy is ultimately set to
                               * be "manual", the buffer allocation is guaranteed to
                               * fail, if only because the allocation requires two
                               * buffers.  (We set the the size to the highest
                               * multiple of 128m because it ensures that the size
                               * will remain a multiple of a megabyte when
                               * repeatedly halved -- all the way down to 15m.)
                               */
                              val = LONG_MAX - (1 << 27) + 1;
                    }
          }

          state->dts_options[option] = val;

          return (0);
}

static void
dtrace_state_destroy(dtrace_state_t *state)
{
          dtrace_ecb_t *ecb;
          dtrace_vstate_t *vstate = &state->dts_vstate;
#ifdef illumos
          minor_t minor = getminor(state->dts_dev);
#endif
          int i, bufsize = NCPU * sizeof (dtrace_buffer_t);
          dtrace_speculation_t *spec = state->dts_speculations;
          int nspec = state->dts_nspeculations;
          uint32_t match;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(MUTEX_HELD(&cpu_lock));

          /*
           * First, retract any retained enablings for this state.
           */
          dtrace_enabling_retract(state);
          ASSERT(state->dts_nretained == 0);

          if (state->dts_activity == DTRACE_ACTIVITY_ACTIVE ||
              state->dts_activity == DTRACE_ACTIVITY_DRAINING) {
                    /*
                     * We have managed to come into dtrace_state_destroy() on a
                     * hot enabling -- almost certainly because of a disorderly
                     * shutdown of a consumer.  (That is, a consumer that is
                     * exiting without having called dtrace_stop().) In this case,
                     * we're going to set our activity to be KILLED, and then
                     * issue a sync to be sure that everyone is out of probe
                     * context before we start blowing away ECBs.
                     */
                    state->dts_activity = DTRACE_ACTIVITY_KILLED;
                    dtrace_sync();
          }

          /*
           * Release the credential hold we took in dtrace_state_create().
           */
          if (state->dts_cred.dcr_cred != NULL)
                    crfree(state->dts_cred.dcr_cred);

          /*
           * Now we can safely disable and destroy any enabled probes.  Because
           * any DTRACE_PRIV_KERNEL probes may actually be slowing our progress
           * (especially if they're all enabled), we take two passes through the
           * ECBs:  in the first, we disable just DTRACE_PRIV_KERNEL probes, and
           * in the second we disable whatever is left over.
           */
          for (match = DTRACE_PRIV_KERNEL; ; match = 0) {
                    for (i = 0; i < state->dts_necbs; i++) {
                              if ((ecb = state->dts_ecbs[i]) == NULL)
                                        continue;

                              if (match && ecb->dte_probe != NULL) {
                                        dtrace_probe_t *probe = ecb->dte_probe;
                                        dtrace_provider_t *prov = probe->dtpr_provider;

                                        if (!(prov->dtpv_priv.dtpp_flags & match))
                                                  continue;
                              }

                              dtrace_ecb_disable(ecb);
                              dtrace_ecb_destroy(ecb);
                    }

                    if (!match)
                              break;
          }

          /*
           * Before we free the buffers, perform one more sync to assure that
           * every CPU is out of probe context.
           */
          dtrace_sync();

          dtrace_buffer_free(state->dts_buffer);
          dtrace_buffer_free(state->dts_aggbuffer);

          for (i = 0; i < nspec; i++)
                    dtrace_buffer_free(spec[i].dtsp_buffer);

#ifdef illumos
          if (state->dts_cleaner != CYCLIC_NONE)
                    cyclic_remove(state->dts_cleaner);

          if (state->dts_deadman != CYCLIC_NONE)
                    cyclic_remove(state->dts_deadman);
#endif
#ifdef __FreeBSD__
          callout_stop(&state->dts_cleaner);
          callout_drain(&state->dts_cleaner);
          callout_stop(&state->dts_deadman);
          callout_drain(&state->dts_deadman);
#endif
#ifdef __NetBSD__
          if (state->dts_cleaner != NULL)
                    dtrace_state_worker_remove(state->dts_cleaner);

          if (state->dts_deadman != NULL)
                    dtrace_state_worker_remove(state->dts_deadman);
#endif

          dtrace_dstate_fini(&vstate->dtvs_dynvars);
          dtrace_vstate_fini(vstate);
          if (state->dts_ecbs != NULL)
                    kmem_free(state->dts_ecbs, state->dts_necbs * sizeof (dtrace_ecb_t *));

          if (state->dts_aggregations != NULL) {
#ifdef DEBUG
                    for (i = 0; i < state->dts_naggregations; i++)
                              ASSERT(state->dts_aggregations[i] == NULL);
#endif
                    ASSERT(state->dts_naggregations > 0);
                    kmem_free(state->dts_aggregations,
                        state->dts_naggregations * sizeof (dtrace_aggregation_t *));
          }

          kmem_free(state->dts_buffer, bufsize);
          kmem_free(state->dts_aggbuffer, bufsize);

          for (i = 0; i < nspec; i++)
                    kmem_free(spec[i].dtsp_buffer, bufsize);

          if (spec != NULL)
                    kmem_free(spec, nspec * sizeof (dtrace_speculation_t));

          dtrace_format_destroy(state);

          if (state->dts_aggid_arena != NULL) {
#if defined(illumos) || defined(__NetBSD__)
                    vmem_destroy(state->dts_aggid_arena);
#else
                    delete_unrhdr(state->dts_aggid_arena);
#endif
                    state->dts_aggid_arena = NULL;
          }
#ifdef illumos
          ddi_soft_state_free(dtrace_softstate, minor);
          vmem_free(dtrace_minor, (void *)(uintptr_t)minor, 1);
#endif
#ifdef __NetBSD__
          kmem_free(state, sizeof(dtrace_state_t));
#endif
}

/*
 * DTrace Anonymous Enabling Functions
 */
static dtrace_state_t *
dtrace_anon_grab(void)
{
          dtrace_state_t *state;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          if ((state = dtrace_anon.dta_state) == NULL) {
                    ASSERT(dtrace_anon.dta_enabling == NULL);
                    return (NULL);
          }

          ASSERT(dtrace_anon.dta_enabling != NULL);
          ASSERT(dtrace_retained != NULL);

          dtrace_enabling_destroy(dtrace_anon.dta_enabling);
          dtrace_anon.dta_enabling = NULL;
          dtrace_anon.dta_state = NULL;

          return (state);
}

static void
dtrace_anon_property(void)
{
          int i, rv;
          dtrace_state_t *state;
          dof_hdr_t *dof;
          char c[32];                   /* enough for "dof-data-" + digits */

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(MUTEX_HELD(&cpu_lock));

          for (i = 0; ; i++) {
                    (void) snprintf(c, sizeof (c), "dof-data-%d", i);

                    dtrace_err_verbose = 1;

                    if ((dof = dtrace_dof_property(c)) == NULL) {
                              dtrace_err_verbose = 0;
                              break;
                    }

#ifdef illumos
                    /*
                     * We want to create anonymous state, so we need to transition
                     * the kernel debugger to indicate that DTrace is active.  If
                     * this fails (e.g. because the debugger has modified text in
                     * some way), we won't continue with the processing.
                     */
                    if (kdi_dtrace_set(KDI_DTSET_DTRACE_ACTIVATE) != 0) {
                              cmn_err(CE_NOTE, "kernel debugger active; anonymous "
                                  "enabling ignored.");
                              dtrace_dof_destroy(dof);
                              break;
                    }
#endif

                    /*
                     * If we haven't allocated an anonymous state, we'll do so now.
                     */
                    if ((state = dtrace_anon.dta_state) == NULL) {
                              state = dtrace_state_create(NULL, NULL);
                              dtrace_anon.dta_state = state;

                              if (state == NULL) {
                                        /*
                                         * This basically shouldn't happen:  the only
                                         * failure mode from dtrace_state_create() is a
                                         * failure of ddi_soft_state_zalloc() that
                                         * itself should never happen.  Still, the
                                         * interface allows for a failure mode, and
                                         * we want to fail as gracefully as possible:
                                         * we'll emit an error message and cease
                                         * processing anonymous state in this case.
                                         */
                                        cmn_err(CE_WARN, "failed to create "
                                            "anonymous state");
                                        dtrace_dof_destroy(dof);
                                        break;
                              }
                    }

                    rv = dtrace_dof_slurp(dof, &state->dts_vstate, CRED(),
                        &dtrace_anon.dta_enabling, 0, 0, B_TRUE);

                    if (rv == 0)
                              rv = dtrace_dof_options(dof, state);

                    dtrace_err_verbose = 0;
                    dtrace_dof_destroy(dof);

                    if (rv != 0) {
                              /*
                               * This is malformed DOF; chuck any anonymous state
                               * that we created.
                               */
                              ASSERT(dtrace_anon.dta_enabling == NULL);
                              dtrace_state_destroy(state);
                              dtrace_anon.dta_state = NULL;
                              break;
                    }

                    ASSERT(dtrace_anon.dta_enabling != NULL);
          }

          if (dtrace_anon.dta_enabling != NULL) {
                    int rval;

                    /*
                     * dtrace_enabling_retain() can only fail because we are
                     * trying to retain more enablings than are allowed -- but
                     * we only have one anonymous enabling, and we are guaranteed
                     * to be allowed at least one retained enabling; we assert
                     * that dtrace_enabling_retain() returns success.
                     */
                    rval = dtrace_enabling_retain(dtrace_anon.dta_enabling);
                    ASSERT(rval == 0);

                    dtrace_enabling_dump(dtrace_anon.dta_enabling);
          }
}

/*
 * DTrace Helper Functions
 */
static void
dtrace_helper_trace(dtrace_helper_action_t *helper,
    dtrace_mstate_t *mstate, dtrace_vstate_t *vstate, int where)
{
          uint32_t size, next, nnext, i;
          dtrace_helptrace_t *ent, *buffer;
          uint16_t flags = cpu_core[curcpu_id].cpuc_dtrace_flags;

          if ((buffer = dtrace_helptrace_buffer) == NULL)
                    return;

          ASSERT(vstate->dtvs_nlocals <= dtrace_helptrace_nlocals);

          /*
           * What would a tracing framework be without its own tracing
           * framework?  (Well, a hell of a lot simpler, for starters...)
           */
          size = sizeof (dtrace_helptrace_t) + dtrace_helptrace_nlocals *
              sizeof (uint64_t) - sizeof (uint64_t);

          /*
           * Iterate until we can allocate a slot in the trace buffer.
           */
          do {
                    next = dtrace_helptrace_next;

                    if (next + size < dtrace_helptrace_bufsize) {
                              nnext = next + size;
                    } else {
                              nnext = size;
                    }
          } while (dtrace_cas32(&dtrace_helptrace_next, next, nnext) != next);

          /*
           * We have our slot; fill it in.
           */
          if (nnext == size) {
                    dtrace_helptrace_wrapped++;
                    next = 0;
          }

          ent = (dtrace_helptrace_t *)((uintptr_t)buffer + next);
          ent->dtht_helper = helper;
          ent->dtht_where = where;
          ent->dtht_nlocals = vstate->dtvs_nlocals;

          ent->dtht_fltoffs = (mstate->dtms_present & DTRACE_MSTATE_FLTOFFS) ?
              mstate->dtms_fltoffs : -1;
          ent->dtht_fault = DTRACE_FLAGS2FLT(flags);
          ent->dtht_illval = cpu_core[curcpu_id].cpuc_dtrace_illval;

          for (i = 0; i < vstate->dtvs_nlocals; i++) {
                    dtrace_statvar_t *svar;

                    if ((svar = vstate->dtvs_locals[i]) == NULL)
                              continue;

                    ASSERT(svar->dtsv_size >= NCPU * sizeof (uint64_t));
                    ent->dtht_locals[i] =
                        ((uint64_t *)(uintptr_t)svar->dtsv_data)[curcpu_id];
          }
}

static uint64_t
dtrace_helper(int which, dtrace_mstate_t *mstate,
    dtrace_state_t *state, uint64_t arg0, uint64_t arg1)
{
          uint16_t *flags = &cpu_core[curcpu_id].cpuc_dtrace_flags;
          uint64_t sarg0 = mstate->dtms_arg[0];
          uint64_t sarg1 = mstate->dtms_arg[1];
          uint64_t rval = 0;
          dtrace_helpers_t *helpers = curproc->p_dtrace_helpers;
          dtrace_helper_action_t *helper;
          dtrace_vstate_t *vstate;
          dtrace_difo_t *pred;
          int i, trace = dtrace_helptrace_buffer != NULL;

          ASSERT(which >= 0 && which < DTRACE_NHELPER_ACTIONS);

          if (helpers == NULL)
                    return (0);

          if ((helper = helpers->dthps_actions[which]) == NULL)
                    return (0);

          vstate = &helpers->dthps_vstate;
          mstate->dtms_arg[0] = arg0;
          mstate->dtms_arg[1] = arg1;

          /*
           * Now iterate over each helper.  If its predicate evaluates to 'true',
           * we'll call the corresponding actions.  Note that the below calls
           * to dtrace_dif_emulate() may set faults in machine state.  This is
           * okay:  our caller (the outer dtrace_dif_emulate()) will simply plow
           * the stored DIF offset with its own (which is the desired behavior).
           * Also, note the calls to dtrace_dif_emulate() may allocate scratch
           * from machine state; this is okay, too.
           */
          for (; helper != NULL; helper = helper->dtha_next) {
                    if ((pred = helper->dtha_predicate) != NULL) {
                              if (trace)
                                        dtrace_helper_trace(helper, mstate, vstate, 0);

                              if (!dtrace_dif_emulate(pred, mstate, vstate, state))
                                        goto next;

                              if (*flags & CPU_DTRACE_FAULT)
                                        goto err;
                    }

                    for (i = 0; i < helper->dtha_nactions; i++) {
                              if (trace)
                                        dtrace_helper_trace(helper,
                                            mstate, vstate, i + 1);

                              rval = dtrace_dif_emulate(helper->dtha_actions[i],
                                  mstate, vstate, state);

                              if (*flags & CPU_DTRACE_FAULT)
                                        goto err;
                    }

next:
                    if (trace)
                              dtrace_helper_trace(helper, mstate, vstate,
                                  DTRACE_HELPTRACE_NEXT);
          }

          if (trace)
                    dtrace_helper_trace(helper, mstate, vstate,
                        DTRACE_HELPTRACE_DONE);

          /*
           * Restore the arg0 that we saved upon entry.
           */
          mstate->dtms_arg[0] = sarg0;
          mstate->dtms_arg[1] = sarg1;

          return (rval);

err:
          if (trace)
                    dtrace_helper_trace(helper, mstate, vstate,
                        DTRACE_HELPTRACE_ERR);

          /*
           * Restore the arg0 that we saved upon entry.
           */
          mstate->dtms_arg[0] = sarg0;
          mstate->dtms_arg[1] = sarg1;

          return (0);
}

static void
dtrace_helper_action_destroy(dtrace_helper_action_t *helper,
    dtrace_vstate_t *vstate)
{
          int i;

          if (helper->dtha_predicate != NULL)
                    dtrace_difo_release(helper->dtha_predicate, vstate);

          for (i = 0; i < helper->dtha_nactions; i++) {
                    ASSERT(helper->dtha_actions[i] != NULL);
                    dtrace_difo_release(helper->dtha_actions[i], vstate);
          }

          kmem_free(helper->dtha_actions,
              helper->dtha_nactions * sizeof (dtrace_difo_t *));
          kmem_free(helper, sizeof (dtrace_helper_action_t));
}

static int
dtrace_helper_destroygen(dtrace_helpers_t *help, int gen)
{
          proc_t *p = curproc;
          dtrace_vstate_t *vstate;
          int i;

          if (help == NULL)
                    help = p->p_dtrace_helpers;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          if (help == NULL || gen > help->dthps_generation)
                    return (EINVAL);

          vstate = &help->dthps_vstate;

          for (i = 0; i < DTRACE_NHELPER_ACTIONS; i++) {
                    dtrace_helper_action_t *last = NULL, *h, *next;

                    for (h = help->dthps_actions[i]; h != NULL; h = next) {
                              next = h->dtha_next;

                              if (h->dtha_generation == gen) {
                                        if (last != NULL) {
                                                  last->dtha_next = next;
                                        } else {
                                                  help->dthps_actions[i] = next;
                                        }

                                        dtrace_helper_action_destroy(h, vstate);
                              } else {
                                        last = h;
                              }
                    }
          }

          /*
           * Interate until we've cleared out all helper providers with the
           * given generation number.
           */
          for (;;) {
                    dtrace_helper_provider_t *prov;

                    /*
                     * Look for a helper provider with the right generation. We
                     * have to start back at the beginning of the list each time
                     * because we drop dtrace_lock. It's unlikely that we'll make
                     * more than two passes.
                     */
                    for (i = 0; i < help->dthps_nprovs; i++) {
                              prov = help->dthps_provs[i];

                              if (prov->dthp_generation == gen)
                                        break;
                    }

                    /*
                     * If there were no matches, we're done.
                     */
                    if (i == help->dthps_nprovs)
                              break;

                    /*
                     * Move the last helper provider into this slot.
                     */
                    help->dthps_nprovs--;
                    help->dthps_provs[i] = help->dthps_provs[help->dthps_nprovs];
                    help->dthps_provs[help->dthps_nprovs] = NULL;

                    mutex_exit(&dtrace_lock);

                    /*
                     * If we have a meta provider, remove this helper provider.
                     */
                    mutex_enter(&dtrace_meta_lock);
                    if (dtrace_meta_pid != NULL) {
                              ASSERT(dtrace_deferred_pid == NULL);
                              dtrace_helper_provider_remove(&prov->dthp_prov,
                                  p->p_pid);
                    }
                    mutex_exit(&dtrace_meta_lock);

                    dtrace_helper_provider_destroy(prov);

                    mutex_enter(&dtrace_lock);
          }

          return (0);
}

static int
dtrace_helper_validate(dtrace_helper_action_t *helper)
{
          int err = 0, i;
          dtrace_difo_t *dp;

          if ((dp = helper->dtha_predicate) != NULL)
                    err += dtrace_difo_validate_helper(dp);

          for (i = 0; i < helper->dtha_nactions; i++)
                    err += dtrace_difo_validate_helper(helper->dtha_actions[i]);

          return (err == 0);
}

static int
dtrace_helper_action_add(int which, dtrace_ecbdesc_t *ep,
    dtrace_helpers_t *help)
{
          dtrace_helper_action_t *helper, *last;
          dtrace_actdesc_t *act;
          dtrace_vstate_t *vstate;
          dtrace_predicate_t *pred;
          int count = 0, nactions = 0, i;

          if (which < 0 || which >= DTRACE_NHELPER_ACTIONS)
                    return (EINVAL);

          last = help->dthps_actions[which];
          vstate = &help->dthps_vstate;

          for (count = 0; last != NULL; last = last->dtha_next) {
                    count++;
                    if (last->dtha_next == NULL)
                              break;
          }

          /*
           * If we already have dtrace_helper_actions_max helper actions for this
           * helper action type, we'll refuse to add a new one.
           */
          if (count >= dtrace_helper_actions_max)
                    return (ENOSPC);

          helper = kmem_zalloc(sizeof (dtrace_helper_action_t), KM_SLEEP);
          helper->dtha_generation = help->dthps_generation;

          if ((pred = ep->dted_pred.dtpdd_predicate) != NULL) {
                    ASSERT(pred->dtp_difo != NULL);
                    dtrace_difo_hold(pred->dtp_difo);
                    helper->dtha_predicate = pred->dtp_difo;
          }

          for (act = ep->dted_action; act != NULL; act = act->dtad_next) {
                    if (act->dtad_kind != DTRACEACT_DIFEXPR)
                              goto err;

                    if (act->dtad_difo == NULL)
                              goto err;

                    nactions++;
          }

          helper->dtha_actions = kmem_zalloc(sizeof (dtrace_difo_t *) *
              (helper->dtha_nactions = nactions), KM_SLEEP);

          for (act = ep->dted_action, i = 0; act != NULL; act = act->dtad_next) {
                    dtrace_difo_hold(act->dtad_difo);
                    helper->dtha_actions[i++] = act->dtad_difo;
          }

          if (!dtrace_helper_validate(helper))
                    goto err;

          if (last == NULL) {
                    help->dthps_actions[which] = helper;
          } else {
                    last->dtha_next = helper;
          }

          if (vstate->dtvs_nlocals > dtrace_helptrace_nlocals) {
                    dtrace_helptrace_nlocals = vstate->dtvs_nlocals;
                    dtrace_helptrace_next = 0;
          }

          return (0);
err:
          dtrace_helper_action_destroy(helper, vstate);
          return (EINVAL);
}

static void
dtrace_helper_provider_register(proc_t *p, dtrace_helpers_t *help,
    dof_helper_t *dofhp)
{
          ASSERT(MUTEX_NOT_HELD(&dtrace_lock));

          mutex_enter(&dtrace_meta_lock);
          mutex_enter(&dtrace_lock);

          if (!dtrace_attached() || dtrace_meta_pid == NULL) {
                    /*
                     * If the dtrace module is loaded but not attached, or if
                     * there aren't isn't a meta provider registered to deal with
                     * these provider descriptions, we need to postpone creating
                     * the actual providers until later.
                     */

                    if (help->dthps_next == NULL && help->dthps_prev == NULL &&
                        dtrace_deferred_pid != help) {
                              help->dthps_deferred = 1;
                              help->dthps_pid = p->p_pid;
                              help->dthps_next = dtrace_deferred_pid;
                              help->dthps_prev = NULL;
                              if (dtrace_deferred_pid != NULL)
                                        dtrace_deferred_pid->dthps_prev = help;
                              dtrace_deferred_pid = help;
                    }

                    mutex_exit(&dtrace_lock);

          } else if (dofhp != NULL) {
                    /*
                     * If the dtrace module is loaded and we have a particular
                     * helper provider description, pass that off to the
                     * meta provider.
                     */

                    mutex_exit(&dtrace_lock);

                    dtrace_helper_provide(dofhp, p->p_pid);

          } else {
                    /*
                     * Otherwise, just pass all the helper provider descriptions
                     * off to the meta provider.
                     */

                    int i;
                    mutex_exit(&dtrace_lock);

                    for (i = 0; i < help->dthps_nprovs; i++) {
                              dtrace_helper_provide(&help->dthps_provs[i]->dthp_prov,
                                  p->p_pid);
                    }
          }

          mutex_exit(&dtrace_meta_lock);
}

static int
dtrace_helper_provider_add(dof_helper_t *dofhp, dtrace_helpers_t *help, int gen)
{
          dtrace_helper_provider_t *hprov, **tmp_provs;
          uint_t tmp_maxprovs, i;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(help != NULL);

          /*
           * If we already have dtrace_helper_providers_max helper providers,
           * we're refuse to add a new one.
           */
          if (help->dthps_nprovs >= dtrace_helper_providers_max)
                    return (ENOSPC);

          /*
           * Check to make sure this isn't a duplicate.
           */
          for (i = 0; i < help->dthps_nprovs; i++) {
                    if (dofhp->dofhp_addr ==
                        help->dthps_provs[i]->dthp_prov.dofhp_addr)
                              return (EALREADY);
          }

          hprov = kmem_zalloc(sizeof (dtrace_helper_provider_t), KM_SLEEP);
          hprov->dthp_prov = *dofhp;
          hprov->dthp_ref = 1;
          hprov->dthp_generation = gen;

          /*
           * Allocate a bigger table for helper providers if it's already full.
           */
          if (help->dthps_maxprovs == help->dthps_nprovs) {
                    tmp_maxprovs = help->dthps_maxprovs;
                    tmp_provs = help->dthps_provs;

                    if (help->dthps_maxprovs == 0)
                              help->dthps_maxprovs = 2;
                    else
                              help->dthps_maxprovs *= 2;
                    if (help->dthps_maxprovs > dtrace_helper_providers_max)
                              help->dthps_maxprovs = dtrace_helper_providers_max;

                    ASSERT(tmp_maxprovs < help->dthps_maxprovs);

                    help->dthps_provs = kmem_zalloc(help->dthps_maxprovs *
                        sizeof (dtrace_helper_provider_t *), KM_SLEEP);

                    if (tmp_provs != NULL) {
                              bcopy(tmp_provs, help->dthps_provs, tmp_maxprovs *
                                  sizeof (dtrace_helper_provider_t *));
                              kmem_free(tmp_provs, tmp_maxprovs *
                                  sizeof (dtrace_helper_provider_t *));
                    }
          }

          help->dthps_provs[help->dthps_nprovs] = hprov;
          help->dthps_nprovs++;

          return (0);
}

static void
dtrace_helper_provider_destroy(dtrace_helper_provider_t *hprov)
{
          mutex_enter(&dtrace_lock);

          if (--hprov->dthp_ref == 0) {
                    dof_hdr_t *dof;
                    mutex_exit(&dtrace_lock);
                    dof = (dof_hdr_t *)(uintptr_t)hprov->dthp_prov.dofhp_dof;
                    dtrace_dof_destroy(dof);
                    kmem_free(hprov, sizeof (dtrace_helper_provider_t));
          } else {
                    mutex_exit(&dtrace_lock);
          }
}

static int
dtrace_helper_provider_validate(dof_hdr_t *dof, dof_sec_t *sec)
{
          uintptr_t daddr = (uintptr_t)dof;
          dof_sec_t *str_sec, *prb_sec, *arg_sec, *off_sec, *enoff_sec;
          dof_provider_t *provider;
          dof_probe_t *probe;
          uint8_t *arg;
          char *strtab, *typestr;
          dof_stridx_t typeidx;
          size_t typesz;
          uint_t nprobes, j, k;

          ASSERT(sec->dofs_type == DOF_SECT_PROVIDER);

          if (sec->dofs_offset & (sizeof (uint_t) - 1)) {
                    dtrace_dof_error(dof, "misaligned section offset");
                    return (-1);
          }

          /*
           * The section needs to be large enough to contain the DOF provider
           * structure appropriate for the given version.
           */
          if (sec->dofs_size <
              ((dof->dofh_ident[DOF_ID_VERSION] == DOF_VERSION_1) ?
              offsetof(dof_provider_t, dofpv_prenoffs) :
              sizeof (dof_provider_t))) {
                    dtrace_dof_error(dof, "provider section too small");
                    return (-1);
          }

          provider = (dof_provider_t *)(uintptr_t)(daddr + sec->dofs_offset);
          str_sec = dtrace_dof_sect(dof, DOF_SECT_STRTAB, provider->dofpv_strtab);
          prb_sec = dtrace_dof_sect(dof, DOF_SECT_PROBES, provider->dofpv_probes);
          arg_sec = dtrace_dof_sect(dof, DOF_SECT_PRARGS, provider->dofpv_prargs);
          off_sec = dtrace_dof_sect(dof, DOF_SECT_PROFFS, provider->dofpv_proffs);

          if (str_sec == NULL || prb_sec == NULL ||
              arg_sec == NULL || off_sec == NULL)
                    return (-1);

          enoff_sec = NULL;

          if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1 &&
              provider->dofpv_prenoffs != DOF_SECT_NONE &&
              (enoff_sec = dtrace_dof_sect(dof, DOF_SECT_PRENOFFS,
              provider->dofpv_prenoffs)) == NULL)
                    return (-1);

          strtab = (char *)(uintptr_t)(daddr + str_sec->dofs_offset);

          if (provider->dofpv_name >= str_sec->dofs_size ||
              strlen(strtab + provider->dofpv_name) >= DTRACE_PROVNAMELEN) {
                    dtrace_dof_error(dof, "invalid provider name");
                    return (-1);
          }

          if (prb_sec->dofs_entsize == 0 ||
              prb_sec->dofs_entsize > prb_sec->dofs_size) {
                    dtrace_dof_error(dof, "invalid entry size");
                    return (-1);
          }

          if (prb_sec->dofs_entsize & (sizeof (uintptr_t) - 1)) {
                    dtrace_dof_error(dof, "misaligned entry size");
                    return (-1);
          }

          if (off_sec->dofs_entsize != sizeof (uint32_t)) {
                    dtrace_dof_error(dof, "invalid entry size");
                    return (-1);
          }

          if (off_sec->dofs_offset & (sizeof (uint32_t) - 1)) {
                    dtrace_dof_error(dof, "misaligned section offset");
                    return (-1);
          }

          if (arg_sec->dofs_entsize != sizeof (uint8_t)) {
                    dtrace_dof_error(dof, "invalid entry size");
                    return (-1);
          }

          arg = (uint8_t *)(uintptr_t)(daddr + arg_sec->dofs_offset);

          nprobes = prb_sec->dofs_size / prb_sec->dofs_entsize;

          /*
           * Take a pass through the probes to check for errors.
           */
          for (j = 0; j < nprobes; j++) {
                    probe = (dof_probe_t *)(uintptr_t)(daddr +
                        prb_sec->dofs_offset + j * prb_sec->dofs_entsize);

                    if (probe->dofpr_func >= str_sec->dofs_size) {
                              dtrace_dof_error(dof, "invalid function name");
                              return (-1);
                    }

                    if (strlen(strtab + probe->dofpr_func) >= DTRACE_FUNCNAMELEN) {
                              dtrace_dof_error(dof, "function name too long");
                              /*
                               * Keep going if the function name is too long.
                               * Unlike provider and probe names, we cannot reasonably
                               * impose restrictions on function names, since they're
                               * a property of the code being instrumented. We will
                               * skip this probe in dtrace_helper_provide_one().
                               */
                    }

                    if (probe->dofpr_name >= str_sec->dofs_size ||
                        strlen(strtab + probe->dofpr_name) >= DTRACE_NAMELEN) {
                              dtrace_dof_error(dof, "invalid probe name");
                              return (-1);
                    }

                    /*
                     * The offset count must not wrap the index, and the offsets
                     * must also not overflow the section's data.
                     */
                    if (probe->dofpr_offidx + probe->dofpr_noffs <
                        probe->dofpr_offidx ||
                        (probe->dofpr_offidx + probe->dofpr_noffs) *
                        off_sec->dofs_entsize > off_sec->dofs_size) {
                              dtrace_dof_error(dof, "invalid probe offset");
                              return (-1);
                    }

                    if (dof->dofh_ident[DOF_ID_VERSION] != DOF_VERSION_1) {
                              /*
                               * If there's no is-enabled offset section, make sure
                               * there aren't any is-enabled offsets. Otherwise
                               * perform the same checks as for probe offsets
                               * (immediately above).
                               */
                              if (enoff_sec == NULL) {
                                        if (probe->dofpr_enoffidx != 0 ||
                                            probe->dofpr_nenoffs != 0) {
                                                  dtrace_dof_error(dof, "is-enabled "
                                                      "offsets with null section");
                                                  return (-1);
                                        }
                              } else if (probe->dofpr_enoffidx +
                                  probe->dofpr_nenoffs < probe->dofpr_enoffidx ||
                                  (probe->dofpr_enoffidx + probe->dofpr_nenoffs) *
                                  enoff_sec->dofs_entsize > enoff_sec->dofs_size) {
                                        dtrace_dof_error(dof, "invalid is-enabled "
                                            "offset");
                                        return (-1);
                              }

                              if (probe->dofpr_noffs + probe->dofpr_nenoffs == 0) {
                                        dtrace_dof_error(dof, "zero probe and "
                                            "is-enabled offsets");
                                        return (-1);
                              }
                    } else if (probe->dofpr_noffs == 0) {
                              dtrace_dof_error(dof, "zero probe offsets");
                              return (-1);
                    }

                    if (probe->dofpr_argidx + probe->dofpr_xargc <
                        probe->dofpr_argidx ||
                        (probe->dofpr_argidx + probe->dofpr_xargc) *
                        arg_sec->dofs_entsize > arg_sec->dofs_size) {
                              dtrace_dof_error(dof, "invalid args");
                              return (-1);
                    }

                    typeidx = probe->dofpr_nargv;
                    typestr = strtab + probe->dofpr_nargv;
                    for (k = 0; k < probe->dofpr_nargc; k++) {
                              if (typeidx >= str_sec->dofs_size) {
                                        dtrace_dof_error(dof, "bad "
                                            "native argument type");
                                        return (-1);
                              }

                              typesz = strlen(typestr) + 1;
                              if (typesz > DTRACE_ARGTYPELEN) {
                                        dtrace_dof_error(dof, "native "
                                            "argument type too long");
                                        return (-1);
                              }
                              typeidx += typesz;
                              typestr += typesz;
                    }

                    typeidx = probe->dofpr_xargv;
                    typestr = strtab + probe->dofpr_xargv;
                    for (k = 0; k < probe->dofpr_xargc; k++) {
                              if (arg[probe->dofpr_argidx + k] > probe->dofpr_nargc) {
                                        dtrace_dof_error(dof, "bad "
                                            "native argument index");
                                        return (-1);
                              }

                              if (typeidx >= str_sec->dofs_size) {
                                        dtrace_dof_error(dof, "bad "
                                            "translated argument type");
                                        return (-1);
                              }

                              typesz = strlen(typestr) + 1;
                              if (typesz > DTRACE_ARGTYPELEN) {
                                        dtrace_dof_error(dof, "translated argument "
                                            "type too long");
                                        return (-1);
                              }

                              typeidx += typesz;
                              typestr += typesz;
                    }
          }

          return (0);
}

static int
dtrace_helper_slurp(dof_hdr_t *dof, dof_helper_t *dhp, struct proc *p)
{
          dtrace_helpers_t *help;
          dtrace_vstate_t *vstate;
          dtrace_enabling_t *enab = NULL;
          int i, gen, rv, nhelpers = 0, nprovs = 0, destroy = 1;
          uintptr_t daddr = (uintptr_t)dof;

          ASSERT(MUTEX_HELD(&dtrace_lock));

          if ((help = p->p_dtrace_helpers) == NULL)
                    help = dtrace_helpers_create(p);

          vstate = &help->dthps_vstate;
          if ((rv = dtrace_dof_slurp(dof, vstate, NULL, &enab, dhp->dofhp_addr,
              dhp->dofhp_dof, B_FALSE)) != 0) {
                    dtrace_dof_destroy(dof);
                    return (rv);
          }

          /*
           * Look for helper providers and validate their descriptions.
           */
          for (i = 0; i < dof->dofh_secnum; i++) {
                    dof_sec_t *sec = (dof_sec_t *)(uintptr_t)(daddr +
                        dof->dofh_secoff + i * dof->dofh_secsize);

                    if (sec->dofs_type != DOF_SECT_PROVIDER)
                              continue;

                    if (dtrace_helper_provider_validate(dof, sec) != 0) {
                              dtrace_enabling_destroy(enab);
                              dtrace_dof_destroy(dof);
                              return (-1);
                    }

                    nprovs++;
          }

          /*
           * Now we need to walk through the ECB descriptions in the enabling.
           */
          for (i = 0; i < enab->dten_ndesc; i++) {
                    dtrace_ecbdesc_t *ep = enab->dten_desc[i];
                    dtrace_probedesc_t *desc = &ep->dted_probe;

                    if (strcmp(desc->dtpd_provider, "dtrace") != 0)
                              continue;

                    if (strcmp(desc->dtpd_mod, "helper") != 0)
                              continue;

                    if (strcmp(desc->dtpd_func, "ustack") != 0)
                              continue;

                    if ((rv = dtrace_helper_action_add(DTRACE_HELPER_ACTION_USTACK,
                        ep, help)) != 0) {
                              /*
                               * Adding this helper action failed -- we are now going
                               * to rip out the entire generation and return failure.
                               */
                              (void) dtrace_helper_destroygen(help,
                                  help->dthps_generation);
                              dtrace_enabling_destroy(enab);
                              dtrace_dof_destroy(dof);
                              return (-1);
                    }

                    nhelpers++;
          }

          if (nhelpers < enab->dten_ndesc)
                    dtrace_dof_error(dof, "unmatched helpers");

          gen = help->dthps_generation++;
          dtrace_enabling_destroy(enab);

          if (nprovs > 0) {
                    /*
                     * Now that this is in-kernel, we change the sense of the
                     * members:  dofhp_dof denotes the in-kernel copy of the DOF
                     * and dofhp_addr denotes the address at user-level.
                     */
                    dhp->dofhp_addr = dhp->dofhp_dof;
                    dhp->dofhp_dof = (uint64_t)(uintptr_t)dof;

                    if (dtrace_helper_provider_add(dhp, help, gen) == 0) {
                              mutex_exit(&dtrace_lock);
                              dtrace_helper_provider_register(p, help, dhp);
                              mutex_enter(&dtrace_lock);

                              destroy = 0;
                    }
          }

          if (destroy)
                    dtrace_dof_destroy(dof);

          return (gen);
}

static dtrace_helpers_t *
dtrace_helpers_create(proc_t *p)
{
          dtrace_helpers_t *help;

          ASSERT(MUTEX_HELD(&dtrace_lock));
          ASSERT(p->p_dtrace_helpers == NULL);

          help = kmem_zalloc(sizeof (dtrace_helpers_t), KM_SLEEP);
          help->dthps_actions = kmem_zalloc(sizeof (dtrace_helper_action_t *) *
              DTRACE_NHELPER_ACTIONS, KM_SLEEP);

          p->p_dtrace_helpers = help;
          dtrace_helpers++;

          return (help);
}

#ifdef illumos
static
#endif
void
dtrace_helpers_destroy(proc_t *p)
{
          dtrace_helpers_t *help;
          dtrace_vstate_t *vstate;
#ifdef illumos
          proc_t *p = curproc;
#endif
          int i;

          mutex_enter(&dtrace_lock);

          ASSERT(p->p_dtrace_helpers != NULL);
          ASSERT(dtrace_helpers > 0);

          help = p->p_dtrace_helpers;
          vstate = &help->dthps_vstate;

          /*
           * We're now going to lose the help from this process.
           */
          p->p_dtrace_helpers = NULL;
          dtrace_sync();

          /*
           * Destory the helper actions.
           */
          for (i = 0; i < DTRACE_NHELPER_ACTIONS; i++) {
                    dtrace_helper_action_t *h, *next;

                    for (h = help->dthps_actions[i]; h != NULL; h = next) {
                              next = h->dtha_next;
                              dtrace_helper_action_destroy(h, vstate);
                              h = next;
                    }
          }

          mutex_exit(&dtrace_lock);

          /*
           * Destroy the helper providers.
           */
          if (help->dthps_maxprovs > 0) {
                    mutex_enter(&dtrace_meta_lock);
                    if (dtrace_meta_pid != NULL) {
                              ASSERT(dtrace_deferred_pid == NULL);

                              for (i = 0; i < help->dthps_nprovs; i++) {
                                        dtrace_helper_provider_remove(
                                            &help->dthps_provs[i]->dthp_prov, p->p_pid);
                              }
                    } else {
                              mutex_enter(&dtrace_lock);
                              ASSERT(help->dthps_deferred == 0 ||
                                  help->dthps_next != NULL ||
                                  help->dthps_prev != NULL ||
                                  help == dtrace_deferred_pid);

                              /*
                               * Remove the helper from the deferred list.
                               */
                              if (help->dthps_next != NULL)
                                        help->dthps_next->dthps_prev = help->dthps_prev;
                              if (help->dthps_prev != NULL)
                                        help->dthps_prev->dthps_next = help->dthps_next;
                              if (dtrace_deferred_pid == help) {
                                        dtrace_deferred_pid = help->dthps_next;
                                        ASSERT(help->dthps_prev == NULL);
                              }

                              mutex_exit(&dtrace_lock);
                    }

                    mutex_exit(&dtrace_meta_lock);

                    for (i = 0; i < help->dthps_nprovs; i++) {
                              dtrace_helper_provider_destroy(help->dthps_provs[i]);
                    }

                    kmem_free(help->dthps_provs, help->dthps_maxprovs *
                        sizeof (dtrace_helper_provider_t *));
          }

          mutex_enter(&dtrace_lock);

          dtrace_vstate_fini(&help->dthps_vstate);
          kmem_free(help->dthps_actions,
              sizeof (dtrace_helper_action_t *) * DTRACE_NHELPER_ACTIONS);
          kmem_free(help, sizeof (dtrace_helpers_t));

          --dtrace_helpers;
          mutex_exit(&dtrace_lock);
}

#ifdef illumos
static
#endif
void
dtrace_helpers_duplicate(proc_t *from, proc_t *to)
{
          dtrace_helpers_t *help, *newhelp;
          dtrace_helper_action_t *helper, *new, *last;
          dtrace_difo_t *dp;
          dtrace_vstate_t *vstate;
          int i, j, sz, hasprovs = 0;

          mutex_enter(&dtrace_lock);
          ASSERT(from->p_dtrace_helpers != NULL);
          ASSERT(dtrace_helpers > 0);

          help = from->p_dtrace_helpers;
          newhelp = dtrace_helpers_create(to);
          ASSERT(to->p_dtrace_helpers != NULL);

          newhelp->dthps_generation = help->dthps_generation;
          vstate = &newhelp->dthps_vstate;

          /*
           * Duplicate the helper actions.
           */
          for (i = 0; i < DTRACE_NHELPER_ACTIONS; i++) {
                    if ((helper = help->dthps_actions[i]) == NULL)
                              continue;

                    for (last = NULL; helper != NULL; helper = helper->dtha_next) {
                              new = kmem_zalloc(sizeof (dtrace_helper_action_t),
                                  KM_SLEEP);
                              new->dtha_generation = helper->dtha_generation;

                              if ((dp = helper->dtha_predicate) != NULL) {
                                        dp = dtrace_difo_duplicate(dp, vstate);
                                        new->dtha_predicate = dp;
                              }

                              new->dtha_nactions = helper->dtha_nactions;
                              sz = sizeof (dtrace_difo_t *) * new->dtha_nactions;
                              new->dtha_actions = kmem_alloc(sz, KM_SLEEP);

                              for (j = 0; j < new->dtha_nactions; j++) {
                                        dtrace_difo_t *dp = helper->dtha_actions[j];

                                        ASSERT(dp != NULL);
                                        dp = dtrace_difo_duplicate(dp, vstate);
                                        new->dtha_actions[j] = dp;
                              }

                              if (last != NULL) {
                                        last->dtha_next = new;
                              } else {
                                        newhelp->dthps_actions[i] = new;
                              }

                              last = new;
                    }
          }

          /*
           * Duplicate the helper providers and register them with the
           * DTrace framework.
           */
          if (help->dthps_nprovs > 0) {
                    newhelp->dthps_nprovs = help->dthps_nprovs;
                    newhelp->dthps_maxprovs = help->dthps_nprovs;
                    newhelp->dthps_provs = kmem_alloc(newhelp->dthps_nprovs *
                        sizeof (dtrace_helper_provider_t *), KM_SLEEP);
                    for (i = 0; i < newhelp->dthps_nprovs; i++) {
                              newhelp->dthps_provs[i] = help->dthps_provs[i];
                              newhelp->dthps_provs[i]->dthp_ref++;
                    }

                    hasprovs = 1;
          }

          mutex_exit(&dtrace_lock);

          if (hasprovs)
                    dtrace_helper_provider_register(to, newhelp, NULL);
}

/*
 * DTrace Hook Functions
 */
static void
dtrace_module_loaded(modctl_t *ctl)
{
          dtrace_provider_t *prv;

#ifdef __NetBSD__
          /*
           * We have just one symbol table and CTF table for the entire
           * base kernel, so ignore any other built-in module entries.
           * This means that the module name for a given symbol will change
           * depending on whether the module is built-in or loaded separately.
           */
          if (module_source(ctl) == MODULE_SOURCE_KERNEL &&
              strcmp(module_name(ctl), "netbsd")) {
                    return;
          }
#endif

          mutex_enter(&dtrace_provider_lock);
#ifdef illumos
          mutex_enter(&mod_lock);
#endif

#ifdef illumos
          ASSERT(ctl->mod_busy);
#endif

          /*
           * We're going to call each providers per-module provide operation
           * specifying only this module.
           */
          for (prv = dtrace_provider; prv != NULL; prv = prv->dtpv_next)
                    prv->dtpv_pops.dtps_provide_module(prv->dtpv_arg, ctl);

#ifdef illumos
          mutex_exit(&mod_lock);
#endif
          mutex_exit(&dtrace_provider_lock);

          /*
           * If we have any retained enablings, we need to match against them.
           * Enabling probes requires that cpu_lock be held, and we cannot hold
           * cpu_lock here -- it is legal for cpu_lock to be held when loading a
           * module.  (In particular, this happens when loading scheduling
           * classes.)  So if we have any retained enablings, we need to dispatch
           * our task queue to do the match for us.
           */
          mutex_enter(&dtrace_lock);

          if (dtrace_retained == NULL) {
                    mutex_exit(&dtrace_lock);
                    return;
          }

          (void) taskq_dispatch(dtrace_taskq,
              (task_func_t *)dtrace_enabling_matchall, NULL, TQ_SLEEP);

          mutex_exit(&dtrace_lock);

          /*
           * And now, for a little heuristic sleaze:  in general, we want to
           * match modules as soon as they load.  However, we cannot guarantee
           * this, because it would lead us to the lock ordering violation
           * outlined above.  The common case, of course, is that cpu_lock is
           * _not_ held -- so we delay here for a clock tick, hoping that that's
           * long enough for the task queue to do its work.  If it's not, it's
           * not a serious problem -- it just means that the module that we
           * just loaded may not be immediately instrumentable.
           */
          delay(1);
}

static void
#ifndef __FreeBSD__
dtrace_module_unloaded(modctl_t *ctl)
#else
dtrace_module_unloaded(modctl_t *ctl, int *error)
#endif
{
          dtrace_probe_t template, *probe, *first, *next;
          dtrace_provider_t *prov;
#ifndef illumos
          char modname[DTRACE_MODNAMELEN];
          size_t len;
#endif

#ifdef illumos
          template.dtpr_mod = ctl->mod_modname;
#endif
#ifdef __FreeBSD__
          /* Handle the fact that ctl->filename may end in ".ko". */
          strlcpy(modname, ctl->filename, sizeof(modname));
          len = strlen(ctl->filename);
          if (len > 3 && strcmp(modname + len - 3, ".ko") == 0)
                    modname[len - 3] = '\0';
          template.dtpr_mod = modname;
#endif
#ifdef __NetBSD__
          if (module_source(ctl) == MODULE_SOURCE_KERNEL &&
              strcmp(module_name(ctl), "netbsd")) {
                    return;
          }

          /* Handle the fact that ctl->filename may end in ".kmod". */
          strlcpy(modname, module_name(ctl), sizeof(modname));
          len = strlen(modname);
          if (len > 5 && strcmp(modname + len - 5, ".kmod") == 0)
                    modname[len - 5] = '\0';
          template.dtpr_mod = modname;

#endif

          mutex_enter(&dtrace_provider_lock);
#ifdef illumos
          mutex_enter(&mod_lock);
#endif
          mutex_enter(&dtrace_lock);

#ifdef __FreeBSD__
          if (ctl->nenabled > 0) {
                    /* Don't allow unloads if a probe is enabled. */
                    mutex_exit(&dtrace_provider_lock);
                    mutex_exit(&dtrace_lock);
                    *error = -1;
                    printf(
                              "kldunload: attempt to unload module that has DTrace probes enabled\n");
                    return;
          }
#endif

          if (dtrace_bymod == NULL) {
                    /*
                     * The DTrace module is loaded (obviously) but not attached;
                     * we don't have any work to do.
                     */
                    mutex_exit(&dtrace_provider_lock);
#ifdef illumos
                    mutex_exit(&mod_lock);
#endif
                    mutex_exit(&dtrace_lock);
                    return;
          }

          for (probe = first = dtrace_hash_lookup(dtrace_bymod, &template);
              probe != NULL; probe = probe->dtpr_nextmod) {
                    if (probe->dtpr_ecb != NULL) {
                              mutex_exit(&dtrace_provider_lock);
#ifdef illumos
                              mutex_exit(&mod_lock);
#endif
                              mutex_exit(&dtrace_lock);

                              /*
                               * This shouldn't _actually_ be possible -- we're
                               * unloading a module that has an enabled probe in it.
                               * (It's normally up to the provider to make sure that
                               * this can't happen.)  However, because dtps_enable()
                               * doesn't have a failure mode, there can be an
                               * enable/unload race.  Upshot:  we don't want to
                               * assert, but we're not going to disable the
                               * probe, either.
                               */
                              if (dtrace_err_verbose) {
#ifdef illumos
                                        cmn_err(CE_WARN, "unloaded module '%s' had "
                                            "enabled probes", ctl->mod_modname);
#else
                                        cmn_err(CE_WARN, "unloaded module '%s' had "
                                            "enabled probes", modname);
#endif
                              }

                              return;
                    }
          }

          probe = first;

          for (first = NULL; probe != NULL; probe = next) {
                    ASSERT(dtrace_probes[probe->dtpr_id - 1] == probe);

                    dtrace_probes[probe->dtpr_id - 1] = NULL;

                    next = probe->dtpr_nextmod;
                    dtrace_hash_remove(dtrace_bymod, probe);
                    dtrace_hash_remove(dtrace_byfunc, probe);
                    dtrace_hash_remove(dtrace_byname, probe);

                    if (first == NULL) {
                              first = probe;
                              probe->dtpr_nextmod = NULL;
                    } else {
                              probe->dtpr_nextmod = first;
                              first = probe;
                    }
          }

          /*
           * We've removed all of the module's probes from the hash chains and
           * from the probe array.  Now issue a dtrace_sync() to be sure that
           * everyone has cleared out from any probe array processing.
           */
          dtrace_sync();

          for (probe = first; probe != NULL; probe = first) {
                    first = probe->dtpr_nextmod;
                    prov = probe->dtpr_provider;
                    prov->dtpv_pops.dtps_destroy(prov->dtpv_arg, probe->dtpr_id,
                        probe->dtpr_arg);
                    kmem_free(probe->dtpr_mod, strlen(probe->dtpr_mod) + 1);
                    kmem_free(probe->dtpr_func, strlen(probe->dtpr_func) + 1);
                    kmem_free(probe->dtpr_name, strlen(probe->dtpr_name) + 1);
#ifdef illumos
                    vmem_free(dtrace_arena, (void *)(uintptr_t)probe->dtpr_id, 1);
#endif
#ifdef __FreeBSD__
                    free_unr(dtrace_arena, probe->dtpr_id);
#endif
#ifdef __NetBSD__
                    vmem_free(dtrace_arena, (uintptr_t)probe->dtpr_id, 1);
#endif
                    kmem_free(probe, sizeof (dtrace_probe_t));
          }

          mutex_exit(&dtrace_lock);
#ifdef illumos
          mutex_exit(&mod_lock);
#endif
          mutex_exit(&dtrace_provider_lock);
}

#ifdef __FreeBSD__
static void
dtrace_kld_load(void *arg __unused, linker_file_t lf)
{

          dtrace_module_loaded(lf);
}

static void
dtrace_kld_unload_try(void *arg __unused, linker_file_t lf, int *error)
{

          if (*error != 0)
                    /* We already have an error, so don't do anything. */
                    return;
          dtrace_module_unloaded(lf, error);
}
#endif

#ifdef illumos
static void
dtrace_suspend(void)
{
          dtrace_probe_foreach(offsetof(dtrace_pops_t, dtps_suspend));
}

static void
dtrace_resume(void)
{
          dtrace_probe_foreach(offsetof(dtrace_pops_t, dtps_resume));
}
#endif

static int
dtrace_cpu_setup(cpu_setup_t what, processorid_t cpu)
{
          ASSERT(MUTEX_HELD(&cpu_lock));
          mutex_enter(&dtrace_lock);

          switch (what) {
          case CPU_CONFIG: {
                    dtrace_state_t *state;
                    dtrace_optval_t *opt, rs, c;

                    /*
                     * For now, we only allocate a new buffer for anonymous state.
                     */
                    if ((state = dtrace_anon.dta_state) == NULL)
                              break;

                    if (state->dts_activity != DTRACE_ACTIVITY_ACTIVE)
                              break;

                    opt = state->dts_options;
                    c = opt[DTRACEOPT_CPU];

                    if (c != DTRACE_CPUALL && c != DTRACEOPT_UNSET && c != cpu)
                              break;

                    /*
                     * Regardless of what the actual policy is, we're going to
                     * temporarily set our resize policy to be manual.  We're
                     * also going to temporarily set our CPU option to denote
                     * the newly configured CPU.
                     */
                    rs = opt[DTRACEOPT_BUFRESIZE];
                    opt[DTRACEOPT_BUFRESIZE] = DTRACEOPT_BUFRESIZE_MANUAL;
                    opt[DTRACEOPT_CPU] = (dtrace_optval_t)cpu;

                    (void) dtrace_state_buffers(state);

                    opt[DTRACEOPT_BUFRESIZE] = rs;
                    opt[DTRACEOPT_CPU] = c;

                    break;
          }

          case CPU_UNCONFIG:
                    /*
                     * We don't free the buffer in the CPU_UNCONFIG case.  (The
                     * buffer will be freed when the consumer exits.)
                     */
                    break;

          default:
                    break;
          }

          mutex_exit(&dtrace_lock);
          return (0);
}

#ifdef illumos
static void
dtrace_cpu_setup_initial(processorid_t cpu)
{
          (void) dtrace_cpu_setup(CPU_CONFIG, cpu);
}
#endif

static void
dtrace_toxrange_add(uintptr_t base, uintptr_t limit)
{
          if (dtrace_toxranges >= dtrace_toxranges_max) {
                    int osize, nsize;
                    dtrace_toxrange_t *range;

                    osize = dtrace_toxranges_max * sizeof (dtrace_toxrange_t);

                    if (osize == 0) {
                              ASSERT(dtrace_toxrange == NULL);
                              ASSERT(dtrace_toxranges_max == 0);
                              dtrace_toxranges_max = 1;
                    } else {
                              dtrace_toxranges_max <<= 1;
                    }

                    nsize = dtrace_toxranges_max * sizeof (dtrace_toxrange_t);
                    range = kmem_zalloc(nsize, KM_SLEEP);

                    if (dtrace_toxrange != NULL) {
                              ASSERT(osize != 0);
                              bcopy(dtrace_toxrange, range, osize);
                              kmem_free(dtrace_toxrange, osize);
                    }

                    dtrace_toxrange = range;
          }

          ASSERT(dtrace_toxrange[dtrace_toxranges].dtt_base == 0);
          ASSERT(dtrace_toxrange[dtrace_toxranges].dtt_limit == 0);

          dtrace_toxrange[dtrace_toxranges].dtt_base = base;
          dtrace_toxrange[dtrace_toxranges].dtt_limit = limit;
          dtrace_toxranges++;
}

static void
dtrace_getf_barrier()
{
#ifdef illumos
          /*
           * When we have unprivileged (that is, non-DTRACE_CRV_KERNEL) enablings
           * that contain calls to getf(), this routine will be called on every
           * closef() before either the underlying vnode is released or the
           * file_t itself is freed.  By the time we are here, it is essential
           * that the file_t can no longer be accessed from a call to getf()
           * in probe context -- that assures that a dtrace_sync() can be used
           * to clear out any enablings referring to the old structures.
           */
          if (curthread->t_procp->p_zone->zone_dtrace_getf != 0 ||
              kcred->cr_zone->zone_dtrace_getf != 0)
                    dtrace_sync();
#endif
}

/*
 * DTrace Driver Cookbook Functions
 */
#ifdef illumos
/*ARGSUSED*/
static int
dtrace_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
{
          dtrace_provider_id_t id;
          dtrace_state_t *state = NULL;
          dtrace_enabling_t *enab;

          mutex_enter(&cpu_lock);
          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);

          if (ddi_soft_state_init(&dtrace_softstate,
              sizeof (dtrace_state_t), 0) != 0) {
                    cmn_err(CE_NOTE, "/dev/dtrace failed to initialize soft state");
                    mutex_exit(&cpu_lock);
                    mutex_exit(&dtrace_provider_lock);
                    mutex_exit(&dtrace_lock);
                    return (DDI_FAILURE);
          }

          if (ddi_create_minor_node(devi, DTRACEMNR_DTRACE, S_IFCHR,
              DTRACEMNRN_DTRACE, DDI_PSEUDO, NULL) == DDI_FAILURE ||
              ddi_create_minor_node(devi, DTRACEMNR_HELPER, S_IFCHR,
              DTRACEMNRN_HELPER, DDI_PSEUDO, NULL) == DDI_FAILURE) {
                    cmn_err(CE_NOTE, "/dev/dtrace couldn't create minor nodes");
                    ddi_remove_minor_node(devi, NULL);
                    ddi_soft_state_fini(&dtrace_softstate);
                    mutex_exit(&cpu_lock);
                    mutex_exit(&dtrace_provider_lock);
                    mutex_exit(&dtrace_lock);
                    return (DDI_FAILURE);
          }

          ddi_report_dev(devi);
          dtrace_devi = devi;

          dtrace_modload = dtrace_module_loaded;
          dtrace_modunload = dtrace_module_unloaded;
          dtrace_cpu_init = dtrace_cpu_setup_initial;
          dtrace_helpers_cleanup = dtrace_helpers_destroy;
          dtrace_helpers_fork = dtrace_helpers_duplicate;
          dtrace_cpustart_init = dtrace_suspend;
          dtrace_cpustart_fini = dtrace_resume;
          dtrace_debugger_init = dtrace_suspend;
          dtrace_debugger_fini = dtrace_resume;

          register_cpu_setup_func((cpu_setup_func_t *)dtrace_cpu_setup, NULL);

          ASSERT(MUTEX_HELD(&cpu_lock));

          dtrace_arena = vmem_create("dtrace", (void *)1, UINT32_MAX, 1,
              NULL, NULL, NULL, 0, VM_SLEEP | VMC_IDENTIFIER);
          dtrace_minor = vmem_create("dtrace_minor", (void *)DTRACEMNRN_CLONE,
              UINT32_MAX - DTRACEMNRN_CLONE, 1, NULL, NULL, NULL, 0,
              VM_SLEEP | VMC_IDENTIFIER);
          dtrace_taskq = taskq_create("dtrace_taskq", 1, maxclsyspri,
              1, INT_MAX, 0);

          dtrace_state_cache = kmem_cache_create("dtrace_state_cache",
              sizeof (dtrace_dstate_percpu_t) * NCPU, DTRACE_STATE_ALIGN,
              NULL, NULL, NULL, NULL, NULL, 0);

          ASSERT(MUTEX_HELD(&cpu_lock));
          dtrace_bymod = dtrace_hash_create(offsetof(dtrace_probe_t, dtpr_mod),
              offsetof(dtrace_probe_t, dtpr_nextmod),
              offsetof(dtrace_probe_t, dtpr_prevmod));

          dtrace_byfunc = dtrace_hash_create(offsetof(dtrace_probe_t, dtpr_func),
              offsetof(dtrace_probe_t, dtpr_nextfunc),
              offsetof(dtrace_probe_t, dtpr_prevfunc));

          dtrace_byname = dtrace_hash_create(offsetof(dtrace_probe_t, dtpr_name),
              offsetof(dtrace_probe_t, dtpr_nextname),
              offsetof(dtrace_probe_t, dtpr_prevname));

          if (dtrace_retain_max < 1) {
                    cmn_err(CE_WARN, "illegal value (%lu) for dtrace_retain_max; "
                        "setting to 1", dtrace_retain_max);
                    dtrace_retain_max = 1;
          }

          /*
           * Now discover our toxic ranges.
           */
          dtrace_toxic_ranges(dtrace_toxrange_add);

          /*
           * Before we register ourselves as a provider to our own framework,
           * we would like to assert that dtrace_provider is NULL -- but that's
           * not true if we were loaded as a dependency of a DTrace provider.
           * Once we've registered, we can assert that dtrace_provider is our
           * pseudo provider.
           */
          (void) dtrace_register("dtrace", &dtrace_provider_attr,
              DTRACE_PRIV_NONE, 0, &dtrace_provider_ops, NULL, &id);

          ASSERT(dtrace_provider != NULL);
          ASSERT((dtrace_provider_id_t)dtrace_provider == id);

          dtrace_probeid_begin = dtrace_probe_create((dtrace_provider_id_t)
              dtrace_provider, NULL, NULL, "BEGIN", 0, NULL);
          dtrace_probeid_end = dtrace_probe_create((dtrace_provider_id_t)
              dtrace_provider, NULL, NULL, "END", 0, NULL);
          dtrace_probeid_error = dtrace_probe_create((dtrace_provider_id_t)
              dtrace_provider, NULL, NULL, "ERROR", 1, NULL);

          dtrace_anon_property();
          mutex_exit(&cpu_lock);

          /*
           * If there are already providers, we must ask them to provide their
           * probes, and then match any anonymous enabling against them.  Note
           * that there should be no other retained enablings at this time:
           * the only retained enablings at this time should be the anonymous
           * enabling.
           */
          if (dtrace_anon.dta_enabling != NULL) {
                    ASSERT(dtrace_retained == dtrace_anon.dta_enabling);

                    dtrace_enabling_provide(NULL);
                    state = dtrace_anon.dta_state;

                    /*
                     * We couldn't hold cpu_lock across the above call to
                     * dtrace_enabling_provide(), but we must hold it to actually
                     * enable the probes.  We have to drop all of our locks, pick
                     * up cpu_lock, and regain our locks before matching the
                     * retained anonymous enabling.
                     */
                    mutex_exit(&dtrace_lock);
                    mutex_exit(&dtrace_provider_lock);

                    mutex_enter(&cpu_lock);
                    mutex_enter(&dtrace_provider_lock);
                    mutex_enter(&dtrace_lock);

                    if ((enab = dtrace_anon.dta_enabling) != NULL)
                              (void) dtrace_enabling_match(enab, NULL);

                    mutex_exit(&cpu_lock);
          }

          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);

          if (state != NULL) {
                    /*
                     * If we created any anonymous state, set it going now.
                     */
                    (void) dtrace_state_go(state, &dtrace_anon.dta_beganon);
          }

          return (DDI_SUCCESS);
}
#endif

#ifdef __NetBSD__
static dev_type_open(dtrace_open);

/* Pseudo Device Entry points */
/* Just opens, clones to the fileops below */
const struct cdevsw dtrace_cdevsw = {
          .d_open             = dtrace_open,
          .d_close  = noclose,
          .d_read             = noread,
          .d_write  = nowrite,
          .d_ioctl  = noioctl,
          .d_stop             = nostop,
          .d_tty              = notty,
          .d_poll             = nopoll,
          .d_mmap             = nommap,
          .d_kqfilter         = nokqfilter,
          .d_discard          = nodiscard,
          .d_flag             = D_OTHER | D_MPSAFE
};

static int dtrace_ioctl(struct file *fp, u_long cmd, void *data);
static int dtrace_close(struct file *fp);

static const struct fileops dtrace_fileops = {
          .fo_read = fbadop_read,
          .fo_write = fbadop_write,
          .fo_ioctl = dtrace_ioctl,
          .fo_fcntl = fnullop_fcntl,
          .fo_poll = fnullop_poll,
          .fo_stat = fbadop_stat,
          .fo_close = dtrace_close,
          .fo_kqfilter = fnullop_kqfilter,
};
#endif

#ifndef illumos
static void dtrace_dtr(void *);
#endif

/*ARGSUSED*/
static int
#ifdef illumos
dtrace_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
#endif
#ifdef __FreeBSD_
dtrace_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
#endif
#ifdef __NetBSD__
dtrace_open(dev_t dev, int flags, int mode, struct lwp *l)
#endif
{
          dtrace_state_t *state;
          uint32_t priv;
          uid_t uid;
          zoneid_t zoneid;

#ifdef illumos
          if (getminor(*devp) == DTRACEMNRN_HELPER)
                    return (0);

          /*
           * If this wasn't an open with the "helper" minor, then it must be
           * the "dtrace" minor.
           */
          if (getminor(*devp) == DTRACEMNRN_DTRACE)
                    return (ENXIO);
#endif
#ifdef __FreeBSD__
          cred_t *cred_p = NULL;
          cred_p = dev->si_cred;


#endif
#ifdef __NetBSD__
          cred_t *cred_p = NULL;
          struct file *fp;
          int fd;
          int res;

          if ((res = fd_allocfile(&fp, &fd)) != 0)
                    return res;
          cred_p = l->l_cred;
#endif

          /*
           * If no DTRACE_PRIV_* bits are set in the credential, then the
           * caller lacks sufficient permission to do anything with DTrace.
           */
          dtrace_cred2priv(cred_p, &priv, &uid, &zoneid);
          if (priv == DTRACE_PRIV_NONE) {
                    return (EACCES);
          }

          /*
           * Ask all providers to provide all their probes.
           */
          mutex_enter(&dtrace_provider_lock);
          dtrace_probe_provide(NULL, NULL);
          mutex_exit(&dtrace_provider_lock);

          mutex_enter(&cpu_lock);
          mutex_enter(&dtrace_lock);
          dtrace_opens++;
          dtrace_membar_producer();

#ifdef illumos
          /*
           * If the kernel debugger is active (that is, if the kernel debugger
           * modified text in some way), we won't allow the open.
           */
          if (kdi_dtrace_set(KDI_DTSET_DTRACE_ACTIVATE) != 0) {
                    dtrace_opens--;
                    mutex_exit(&cpu_lock);
                    mutex_exit(&dtrace_lock);
                    return (EBUSY);
          }

          if (dtrace_helptrace_enable && dtrace_helptrace_buffer == NULL) {
                    /*
                     * If DTrace helper tracing is enabled, we need to allocate the
                     * trace buffer and initialize the values.
                     */
                    dtrace_helptrace_buffer =
                        kmem_zalloc(dtrace_helptrace_bufsize, KM_SLEEP);
                    dtrace_helptrace_next = 0;
                    dtrace_helptrace_wrapped = 0;
                    dtrace_helptrace_enable = 0;
          }
          state = dtrace_state_create(devp, cred_p);
#endif
#ifdef __FreeBSD__
          state = dtrace_state_create(dev, NULL);
          devfs_set_cdevpriv(state, dtrace_dtr);
#endif
#ifdef __NetBSD__
          state = dtrace_state_create(&dev, cred_p);
#endif

          mutex_exit(&cpu_lock);

          if (state == NULL) {
#ifdef illumos
                    if (--dtrace_opens == 0 && dtrace_anon.dta_enabling == NULL)
                              (void) kdi_dtrace_set(KDI_DTSET_DTRACE_DEACTIVATE);
#else
                    --dtrace_opens;
#endif
                    mutex_exit(&dtrace_lock);
                    return (EAGAIN);
          }

          mutex_exit(&dtrace_lock);

#ifdef __NetBSD__
          return fd_clone(fp, fd, flags, &dtrace_fileops, state);
#else
          return (0);
#endif
}

/*ARGSUSED*/
#ifdef illumos
static int
dtrace_close(dev_t dev, int flag, int otyp, cred_t *cred_p)
#endif
#ifdef __FreeBSD__
static void
dtrace_dtr(void *data)
#endif
#ifdef __NetBSD__
static int
dtrace_close(struct file *fp)
#endif
{
#ifdef illumos
          minor_t minor = getminor(dev);
          dtrace_state_t *state;
#endif
          dtrace_helptrace_t *buf = NULL;

#ifdef illumos
          if (minor == DTRACEMNRN_HELPER)
                    return (0);

          state = ddi_get_soft_state(dtrace_softstate, minor);
#endif
#ifdef __FreeBSD__
          dtrace_state_t *state = data;
#endif
#ifdef __NetBSD__
          dtrace_state_t *state = (dtrace_state_t *)fp->f_data;
#endif

          mutex_enter(&cpu_lock);
          mutex_enter(&dtrace_lock);

#if defined(illumos) || defined(__NetBSD__)
          if (state->dts_anon)
#else
          if (state != NULL && state->dts_anon)
#endif
          {
                    /*
                     * There is anonymous state. Destroy that first.
                     */
                    ASSERT(dtrace_anon.dta_state == NULL);
                    dtrace_state_destroy(state->dts_anon);
          }

          if (dtrace_helptrace_disable) {
                    /*
                     * If we have been told to disable helper tracing, set the
                     * buffer to NULL before calling into dtrace_state_destroy();
                     * we take advantage of its dtrace_sync() to know that no
                     * CPU is in probe context with enabled helper tracing
                     * after it returns.
                     */
                    buf = dtrace_helptrace_buffer;
                    dtrace_helptrace_buffer = NULL;
          }

#if defined(illumos) || defined(__NetBSD__)
          dtrace_state_destroy(state);
#else
          if (state != NULL) {
                    dtrace_state_destroy(state);
                    kmem_free(state, 0);
          }
#endif

          ASSERT(dtrace_opens > 0);

#ifdef illumos
          /*
           * Only relinquish control of the kernel debugger interface when there
           * are no consumers and no anonymous enablings.
           */
          if (--dtrace_opens == 0 && dtrace_anon.dta_enabling == NULL)
                    (void) kdi_dtrace_set(KDI_DTSET_DTRACE_DEACTIVATE);
#else
          --dtrace_opens;
#endif

          if (buf != NULL) {
                    kmem_free(buf, dtrace_helptrace_bufsize);
                    dtrace_helptrace_disable = 0;
          }

          mutex_exit(&dtrace_lock);
          mutex_exit(&cpu_lock);

#if defined(illumos) || defined(__NetBSD__)
          return (0);
#endif
}

#ifdef illumos
/*ARGSUSED*/
static int
dtrace_ioctl_helper(int cmd, intptr_t arg, int *rv)
{
          int rval;
          dof_helper_t help, *dhp = NULL;

          switch (cmd) {
          case DTRACEHIOC_ADDDOF:
                    if (copyin((void *)arg, &help, sizeof (help)) != 0) {
                              dtrace_dof_error(NULL, "failed to copyin DOF helper");
                              return (EFAULT);
                    }

                    dhp = &help;
                    arg = (intptr_t)help.dofhp_dof;
                    /*FALLTHROUGH*/

          case DTRACEHIOC_ADD: {
                    dof_hdr_t *dof = dtrace_dof_copyin(arg, &rval);

                    if (dof == NULL)
                              return (rval);

                    mutex_enter(&dtrace_lock);

                    /*
                     * dtrace_helper_slurp() takes responsibility for the dof --
                     * it may free it now or it may save it and free it later.
                     */
                    if ((rval = dtrace_helper_slurp(dof, dhp)) != -1) {
                              *rv = rval;
                              rval = 0;
                    } else {
                              rval = EINVAL;
                    }

                    mutex_exit(&dtrace_lock);
                    return (rval);
          }

          case DTRACEHIOC_REMOVE: {
                    mutex_enter(&dtrace_lock);
                    rval = dtrace_helper_destroygen(NULL, arg);
                    mutex_exit(&dtrace_lock);

                    return (rval);
          }

          default:
                    break;
          }

          return (ENOTTY);
}

/*ARGSUSED*/
static int
dtrace_ioctl(dev_t dev, int cmd, intptr_t arg, int md, cred_t *cr, int *rv)
{
          minor_t minor = getminor(dev);
          dtrace_state_t *state;
          int rval;

          if (minor == DTRACEMNRN_HELPER)
                    return (dtrace_ioctl_helper(cmd, arg, rv));

          state = ddi_get_soft_state(dtrace_softstate, minor);

          if (state->dts_anon) {
                    ASSERT(dtrace_anon.dta_state == NULL);
                    state = state->dts_anon;
          }

          switch (cmd) {
          case DTRACEIOC_PROVIDER: {
                    dtrace_providerdesc_t pvd;
                    dtrace_provider_t *pvp;

                    if (copyin((void *)arg, &pvd, sizeof (pvd)) != 0)
                              return (EFAULT);

                    pvd.dtvd_name[DTRACE_PROVNAMELEN - 1] = '\0';
                    mutex_enter(&dtrace_provider_lock);

                    for (pvp = dtrace_provider; pvp != NULL; pvp = pvp->dtpv_next) {
                              if (strcmp(pvp->dtpv_name, pvd.dtvd_name) == 0)
                                        break;
                    }

                    mutex_exit(&dtrace_provider_lock);

                    if (pvp == NULL)
                              return (ESRCH);

                    bcopy(&pvp->dtpv_priv, &pvd.dtvd_priv, sizeof (dtrace_ppriv_t));
                    bcopy(&pvp->dtpv_attr, &pvd.dtvd_attr, sizeof (dtrace_pattr_t));

                    if (copyout(&pvd, (void *)arg, sizeof (pvd)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_EPROBE: {
                    dtrace_eprobedesc_t epdesc;
                    dtrace_ecb_t *ecb;
                    dtrace_action_t *act;
                    void *buf;
                    size_t size;
                    uintptr_t dest;
                    int nrecs;

                    if (copyin((void *)arg, &epdesc, sizeof (epdesc)) != 0)
                              return (EFAULT);

                    mutex_enter(&dtrace_lock);

                    if ((ecb = dtrace_epid2ecb(state, epdesc.dtepd_epid)) == NULL) {
                              mutex_exit(&dtrace_lock);
                              return (EINVAL);
                    }

                    if (ecb->dte_probe == NULL) {
                              mutex_exit(&dtrace_lock);
                              return (EINVAL);
                    }

                    epdesc.dtepd_probeid = ecb->dte_probe->dtpr_id;
                    epdesc.dtepd_uarg = ecb->dte_uarg;
                    epdesc.dtepd_size = ecb->dte_size;

                    nrecs = epdesc.dtepd_nrecs;
                    epdesc.dtepd_nrecs = 0;
                    for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                              if (DTRACEACT_ISAGG(act->dta_kind) || act->dta_intuple)
                                        continue;

                              epdesc.dtepd_nrecs++;
                    }

                    /*
                     * Now that we have the size, we need to allocate a temporary
                     * buffer in which to store the complete description.  We need
                     * the temporary buffer to be able to drop dtrace_lock()
                     * across the copyout(), below.
                     */
                    size = sizeof (dtrace_eprobedesc_t) +
                        (epdesc.dtepd_nrecs * sizeof (dtrace_recdesc_t));

                    buf = kmem_alloc(size, KM_SLEEP);
                    dest = (uintptr_t)buf;

                    bcopy(&epdesc, (void *)dest, sizeof (epdesc));
                    dest += offsetof(dtrace_eprobedesc_t, dtepd_rec[0]);

                    for (act = ecb->dte_action; act != NULL; act = act->dta_next) {
                              if (DTRACEACT_ISAGG(act->dta_kind) || act->dta_intuple)
                                        continue;

                              if (nrecs-- == 0)
                                        break;

                              bcopy(&act->dta_rec, (void *)dest,
                                  sizeof (dtrace_recdesc_t));
                              dest += sizeof (dtrace_recdesc_t);
                    }

                    mutex_exit(&dtrace_lock);

                    if (copyout(buf, (void *)arg, dest - (uintptr_t)buf) != 0) {
                              kmem_free(buf, size);
                              return (EFAULT);
                    }

                    kmem_free(buf, size);
                    return (0);
          }

          case DTRACEIOC_AGGDESC: {
                    dtrace_aggdesc_t aggdesc;
                    dtrace_action_t *act;
                    dtrace_aggregation_t *agg;
                    int nrecs;
                    uint32_t offs;
                    dtrace_recdesc_t *lrec;
                    void *buf;
                    size_t size;
                    uintptr_t dest;

                    if (copyin((void *)arg, &aggdesc, sizeof (aggdesc)) != 0)
                              return (EFAULT);

                    mutex_enter(&dtrace_lock);

                    if ((agg = dtrace_aggid2agg(state, aggdesc.dtagd_id)) == NULL) {
                              mutex_exit(&dtrace_lock);
                              return (EINVAL);
                    }

                    aggdesc.dtagd_epid = agg->dtag_ecb->dte_epid;

                    nrecs = aggdesc.dtagd_nrecs;
                    aggdesc.dtagd_nrecs = 0;

                    offs = agg->dtag_base;
                    lrec = &agg->dtag_action.dta_rec;
                    aggdesc.dtagd_size = lrec->dtrd_offset + lrec->dtrd_size - offs;

                    for (act = agg->dtag_first; ; act = act->dta_next) {
                              ASSERT(act->dta_intuple ||
                                  DTRACEACT_ISAGG(act->dta_kind));

                              /*
                               * If this action has a record size of zero, it
                               * denotes an argument to the aggregating action.
                               * Because the presence of this record doesn't (or
                               * shouldn't) affect the way the data is interpreted,
                               * we don't copy it out to save user-level the
                               * confusion of dealing with a zero-length record.
                               */
                              if (act->dta_rec.dtrd_size == 0) {
                                        ASSERT(agg->dtag_hasarg);
                                        continue;
                              }

                              aggdesc.dtagd_nrecs++;

                              if (act == &agg->dtag_action)
                                        break;
                    }

                    /*
                     * Now that we have the size, we need to allocate a temporary
                     * buffer in which to store the complete description.  We need
                     * the temporary buffer to be able to drop dtrace_lock()
                     * across the copyout(), below.
                     */
                    size = sizeof (dtrace_aggdesc_t) +
                        (aggdesc.dtagd_nrecs * sizeof (dtrace_recdesc_t));

                    buf = kmem_alloc(size, KM_SLEEP);
                    dest = (uintptr_t)buf;

                    bcopy(&aggdesc, (void *)dest, sizeof (aggdesc));
                    dest += offsetof(dtrace_aggdesc_t, dtagd_rec[0]);

                    for (act = agg->dtag_first; ; act = act->dta_next) {
                              dtrace_recdesc_t rec = act->dta_rec;

                              /*
                               * See the comment in the above loop for why we pass
                               * over zero-length records.
                               */
                              if (rec.dtrd_size == 0) {
                                        ASSERT(agg->dtag_hasarg);
                                        continue;
                              }

                              if (nrecs-- == 0)
                                        break;

                              rec.dtrd_offset -= offs;
                              bcopy(&rec, (void *)dest, sizeof (rec));
                              dest += sizeof (dtrace_recdesc_t);

                              if (act == &agg->dtag_action)
                                        break;
                    }

                    mutex_exit(&dtrace_lock);

                    if (copyout(buf, (void *)arg, dest - (uintptr_t)buf) != 0) {
                              kmem_free(buf, size);
                              return (EFAULT);
                    }

                    kmem_free(buf, size);
                    return (0);
          }

          case DTRACEIOC_ENABLE: {
                    dof_hdr_t *dof;
                    dtrace_enabling_t *enab = NULL;
                    dtrace_vstate_t *vstate;
                    int err = 0;

                    *rv = 0;

                    /*
                     * If a NULL argument has been passed, we take this as our
                     * cue to reevaluate our enablings.
                     */
                    if (arg == NULL) {
                              dtrace_enabling_matchall();

                              return (0);
                    }

                    if ((dof = dtrace_dof_copyin(arg, &rval)) == NULL)
                              return (rval);

                    mutex_enter(&cpu_lock);
                    mutex_enter(&dtrace_lock);
                    vstate = &state->dts_vstate;

                    if (state->dts_activity != DTRACE_ACTIVITY_INACTIVE) {
                              mutex_exit(&dtrace_lock);
                              mutex_exit(&cpu_lock);
                              dtrace_dof_destroy(dof);
                              return (EBUSY);
                    }

                    if (dtrace_dof_slurp(dof, vstate, cr, &enab, 0, B_TRUE) != 0) {
                              mutex_exit(&dtrace_lock);
                              mutex_exit(&cpu_lock);
                              dtrace_dof_destroy(dof);
                              return (EINVAL);
                    }

                    if ((rval = dtrace_dof_options(dof, state)) != 0) {
                              dtrace_enabling_destroy(enab);
                              mutex_exit(&dtrace_lock);
                              mutex_exit(&cpu_lock);
                              dtrace_dof_destroy(dof);
                              return (rval);
                    }

                    if ((err = dtrace_enabling_match(enab, rv)) == 0) {
                              err = dtrace_enabling_retain(enab);
                    } else {
                              dtrace_enabling_destroy(enab);
                    }

                    mutex_exit(&cpu_lock);
                    mutex_exit(&dtrace_lock);
                    dtrace_dof_destroy(dof);

                    return (err);
          }

          case DTRACEIOC_REPLICATE: {
                    dtrace_repldesc_t desc;
                    dtrace_probedesc_t *match = &desc.dtrpd_match;
                    dtrace_probedesc_t *create = &desc.dtrpd_create;
                    int err;

                    if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                              return (EFAULT);

                    match->dtpd_provider[DTRACE_PROVNAMELEN - 1] = '\0';
                    match->dtpd_mod[DTRACE_MODNAMELEN - 1] = '\0';
                    match->dtpd_func[DTRACE_FUNCNAMELEN - 1] = '\0';
                    match->dtpd_name[DTRACE_NAMELEN - 1] = '\0';

                    create->dtpd_provider[DTRACE_PROVNAMELEN - 1] = '\0';
                    create->dtpd_mod[DTRACE_MODNAMELEN - 1] = '\0';
                    create->dtpd_func[DTRACE_FUNCNAMELEN - 1] = '\0';
                    create->dtpd_name[DTRACE_NAMELEN - 1] = '\0';

                    mutex_enter(&dtrace_lock);
                    err = dtrace_enabling_replicate(state, match, create);
                    mutex_exit(&dtrace_lock);

                    return (err);
          }

          case DTRACEIOC_PROBEMATCH:
          case DTRACEIOC_PROBES: {
                    dtrace_probe_t *probe = NULL;
                    dtrace_probedesc_t desc;
                    dtrace_probekey_t pkey;
                    dtrace_id_t i;
                    int m = 0;
                    uint32_t priv;
                    uid_t uid;
                    zoneid_t zoneid;

                    if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                              return (EFAULT);

                    desc.dtpd_provider[DTRACE_PROVNAMELEN - 1] = '\0';
                    desc.dtpd_mod[DTRACE_MODNAMELEN - 1] = '\0';
                    desc.dtpd_func[DTRACE_FUNCNAMELEN - 1] = '\0';
                    desc.dtpd_name[DTRACE_NAMELEN - 1] = '\0';

                    /*
                     * Before we attempt to match this probe, we want to give
                     * all providers the opportunity to provide it.
                     */
                    if (desc.dtpd_id == DTRACE_IDNONE) {
                              mutex_enter(&dtrace_provider_lock);
                              dtrace_probe_provide(&desc, NULL);
                              mutex_exit(&dtrace_provider_lock);
                              desc.dtpd_id++;
                    }

                    if (cmd == DTRACEIOC_PROBEMATCH)  {
                              dtrace_probekey(&desc, &pkey);
                              pkey.dtpk_id = DTRACE_IDNONE;
                    }

                    dtrace_cred2priv(cr, &priv, &uid, &zoneid);

                    mutex_enter(&dtrace_lock);

                    if (cmd == DTRACEIOC_PROBEMATCH) {
                              for (i = desc.dtpd_id; i <= dtrace_nprobes; i++) {
                                        if ((probe = dtrace_probes[i - 1]) != NULL &&
                                            (m = dtrace_match_probe(probe, &pkey,
                                            priv, uid, zoneid)) != 0)
                                                  break;
                              }

                              if (m < 0) {
                                        mutex_exit(&dtrace_lock);
                                        return (EINVAL);
                              }

                    } else {
                              for (i = desc.dtpd_id; i <= dtrace_nprobes; i++) {
                                        if ((probe = dtrace_probes[i - 1]) != NULL &&
                                            dtrace_match_priv(probe, priv, uid, zoneid))
                                                  break;
                              }
                    }

                    if (probe == NULL) {
                              mutex_exit(&dtrace_lock);
                              return (ESRCH);
                    }

                    dtrace_probe_description(probe, &desc);
                    mutex_exit(&dtrace_lock);

                    if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_PROBEARG: {
                    dtrace_argdesc_t desc;
                    dtrace_probe_t *probe;
                    dtrace_provider_t *prov;

                    if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                              return (EFAULT);

                    if (desc.dtargd_id == DTRACE_IDNONE)
                              return (EINVAL);

                    if (desc.dtargd_ndx == DTRACE_ARGNONE)
                              return (EINVAL);

                    mutex_enter(&dtrace_provider_lock);
                    mutex_enter(&mod_lock);
                    mutex_enter(&dtrace_lock);

                    if (desc.dtargd_id > dtrace_nprobes) {
                              mutex_exit(&dtrace_lock);
                              mutex_exit(&mod_lock);
                              mutex_exit(&dtrace_provider_lock);
                              return (EINVAL);
                    }

                    if ((probe = dtrace_probes[desc.dtargd_id - 1]) == NULL) {
                              mutex_exit(&dtrace_lock);
                              mutex_exit(&mod_lock);
                              mutex_exit(&dtrace_provider_lock);
                              return (EINVAL);
                    }

                    mutex_exit(&dtrace_lock);

                    prov = probe->dtpr_provider;

                    if (prov->dtpv_pops.dtps_getargdesc == NULL) {
                              /*
                               * There isn't any typed information for this probe.
                               * Set the argument number to DTRACE_ARGNONE.
                               */
                              desc.dtargd_ndx = DTRACE_ARGNONE;
                    } else {
                              desc.dtargd_native[0] = '\0';
                              desc.dtargd_xlate[0] = '\0';
                              desc.dtargd_mapping = desc.dtargd_ndx;

                              prov->dtpv_pops.dtps_getargdesc(prov->dtpv_arg,
                                  probe->dtpr_id, probe->dtpr_arg, &desc);
                    }

                    mutex_exit(&mod_lock);
                    mutex_exit(&dtrace_provider_lock);

                    if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_GO: {
                    processorid_t cpuid;
                    rval = dtrace_state_go(state, &cpuid);

                    if (rval != 0)
                              return (rval);

                    if (copyout(&cpuid, (void *)arg, sizeof (cpuid)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_STOP: {
                    processorid_t cpuid;

                    mutex_enter(&dtrace_lock);
                    rval = dtrace_state_stop(state, &cpuid);
                    mutex_exit(&dtrace_lock);

                    if (rval != 0)
                              return (rval);

                    if (copyout(&cpuid, (void *)arg, sizeof (cpuid)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_DOFGET: {
                    dof_hdr_t hdr, *dof;
                    uint64_t len;

                    if (copyin((void *)arg, &hdr, sizeof (hdr)) != 0)
                              return (EFAULT);

                    mutex_enter(&dtrace_lock);
                    dof = dtrace_dof_create(state);
                    mutex_exit(&dtrace_lock);

                    len = MIN(hdr.dofh_loadsz, dof->dofh_loadsz);
                    rval = copyout(dof, (void *)arg, len);
                    dtrace_dof_destroy(dof);

                    return (rval == 0 ? 0 : EFAULT);
          }

          case DTRACEIOC_AGGSNAP:
          case DTRACEIOC_BUFSNAP: {
                    dtrace_bufdesc_t desc;
                    caddr_t cached;
                    dtrace_buffer_t *buf;

                    if (copyin((void *)arg, &desc, sizeof (desc)) != 0)
                              return (EFAULT);

                    if (desc.dtbd_cpu < 0 || desc.dtbd_cpu >= NCPU)
                              return (EINVAL);

                    mutex_enter(&dtrace_lock);

                    if (cmd == DTRACEIOC_BUFSNAP) {
                              buf = &state->dts_buffer[desc.dtbd_cpu];
                    } else {
                              buf = &state->dts_aggbuffer[desc.dtbd_cpu];
                    }

                    if (buf->dtb_flags & (DTRACEBUF_RING | DTRACEBUF_FILL)) {
                              size_t sz = buf->dtb_offset;

                              if (state->dts_activity != DTRACE_ACTIVITY_STOPPED) {
                                        mutex_exit(&dtrace_lock);
                                        return (EBUSY);
                              }

                              /*
                               * If this buffer has already been consumed, we're
                               * going to indicate that there's nothing left here
                               * to consume.
                               */
                              if (buf->dtb_flags & DTRACEBUF_CONSUMED) {
                                        mutex_exit(&dtrace_lock);

                                        desc.dtbd_size = 0;
                                        desc.dtbd_drops = 0;
                                        desc.dtbd_errors = 0;
                                        desc.dtbd_oldest = 0;
                                        sz = sizeof (desc);

                                        if (copyout(&desc, (void *)arg, sz) != 0)
                                                  return (EFAULT);

                                        return (0);
                              }

                              /*
                               * If this is a ring buffer that has wrapped, we want
                               * to copy the whole thing out.
                               */
                              if (buf->dtb_flags & DTRACEBUF_WRAPPED) {
                                        dtrace_buffer_polish(buf);
                                        sz = buf->dtb_size;
                              }

                              if (copyout(buf->dtb_tomax, desc.dtbd_data, sz) != 0) {
                                        mutex_exit(&dtrace_lock);
                                        return (EFAULT);
                              }

                              desc.dtbd_size = sz;
                              desc.dtbd_drops = buf->dtb_drops;
                              desc.dtbd_errors = buf->dtb_errors;
                              desc.dtbd_oldest = buf->dtb_xamot_offset;
                              desc.dtbd_timestamp = dtrace_gethrtime();

                              mutex_exit(&dtrace_lock);

                              if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                                        return (EFAULT);

                              buf->dtb_flags |= DTRACEBUF_CONSUMED;

                              return (0);
                    }

                    if (buf->dtb_tomax == NULL) {
                              ASSERT(buf->dtb_xamot == NULL);
                              mutex_exit(&dtrace_lock);
                              return (ENOENT);
                    }

                    cached = buf->dtb_tomax;
                    ASSERT(!(buf->dtb_flags & DTRACEBUF_NOSWITCH));

                    dtrace_xcall(desc.dtbd_cpu,
                        (dtrace_xcall_t)dtrace_buffer_switch, buf);

                    state->dts_errors += buf->dtb_xamot_errors;

                    /*
                     * If the buffers did not actually switch, then the cross call
                     * did not take place -- presumably because the given CPU is
                     * not in the ready set.  If this is the case, we'll return
                     * ENOENT.
                     */
                    if (buf->dtb_tomax == cached) {
                              ASSERT(buf->dtb_xamot != cached);
                              mutex_exit(&dtrace_lock);
                              return (ENOENT);
                    }

                    ASSERT(cached == buf->dtb_xamot);

                    /*
                     * We have our snapshot; now copy it out.
                     */
                    if (copyout(buf->dtb_xamot, desc.dtbd_data,
                        buf->dtb_xamot_offset) != 0) {
                              mutex_exit(&dtrace_lock);
                              return (EFAULT);
                    }

                    desc.dtbd_size = buf->dtb_xamot_offset;
                    desc.dtbd_drops = buf->dtb_xamot_drops;
                    desc.dtbd_errors = buf->dtb_xamot_errors;
                    desc.dtbd_oldest = 0;
                    desc.dtbd_timestamp = buf->dtb_switched;

                    mutex_exit(&dtrace_lock);

                    /*
                     * Finally, copy out the buffer description.
                     */
                    if (copyout(&desc, (void *)arg, sizeof (desc)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_CONF: {
                    dtrace_conf_t conf;

                    bzero(&conf, sizeof (conf));
                    conf.dtc_difversion = DIF_VERSION;
                    conf.dtc_difintregs = DIF_DIR_NREGS;
                    conf.dtc_diftupregs = DIF_DTR_NREGS;
                    conf.dtc_ctfmodel = CTF_MODEL_NATIVE;

                    if (copyout(&conf, (void *)arg, sizeof (conf)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_STATUS: {
                    dtrace_status_t stat;
                    dtrace_dstate_t *dstate;
                    int i, j;
                    uint64_t nerrs;

                    /*
                     * See the comment in dtrace_state_deadman() for the reason
                     * for setting dts_laststatus to INT64_MAX before setting
                     * it to the correct value.
                     */
                    state->dts_laststatus = INT64_MAX;
                    dtrace_membar_producer();
                    state->dts_laststatus = dtrace_gethrtime();

                    bzero(&stat, sizeof (stat));

                    mutex_enter(&dtrace_lock);

                    if (state->dts_activity == DTRACE_ACTIVITY_INACTIVE) {
                              mutex_exit(&dtrace_lock);
                              return (ENOENT);
                    }

                    if (state->dts_activity == DTRACE_ACTIVITY_DRAINING)
                              stat.dtst_exiting = 1;

                    nerrs = state->dts_errors;
                    dstate = &state->dts_vstate.dtvs_dynvars;

                    for (i = 0; i < NCPU; i++) {
                              dtrace_dstate_percpu_t *dcpu = &dstate->dtds_percpu[i];

                              stat.dtst_dyndrops += dcpu->dtdsc_drops;
                              stat.dtst_dyndrops_dirty += dcpu->dtdsc_dirty_drops;
                              stat.dtst_dyndrops_rinsing += dcpu->dtdsc_rinsing_drops;

                              if (state->dts_buffer[i].dtb_flags & DTRACEBUF_FULL)
                                        stat.dtst_filled++;

                              nerrs += state->dts_buffer[i].dtb_errors;

                              for (j = 0; j < state->dts_nspeculations; j++) {
                                        dtrace_speculation_t *spec;
                                        dtrace_buffer_t *buf;

                                        spec = &state->dts_speculations[j];
                                        buf = &spec->dtsp_buffer[i];
                                        stat.dtst_specdrops += buf->dtb_xamot_drops;
                              }
                    }

                    stat.dtst_specdrops_busy = state->dts_speculations_busy;
                    stat.dtst_specdrops_unavail = state->dts_speculations_unavail;
                    stat.dtst_stkstroverflows = state->dts_stkstroverflows;
                    stat.dtst_dblerrors = state->dts_dblerrors;
                    stat.dtst_killed =
                        (state->dts_activity == DTRACE_ACTIVITY_KILLED);
                    stat.dtst_errors = nerrs;

                    mutex_exit(&dtrace_lock);

                    if (copyout(&stat, (void *)arg, sizeof (stat)) != 0)
                              return (EFAULT);

                    return (0);
          }

          case DTRACEIOC_FORMAT: {
                    dtrace_fmtdesc_t fmt;
                    char *str;
                    int len;

                    if (copyin((void *)arg, &fmt, sizeof (fmt)) != 0)
                              return (EFAULT);

                    mutex_enter(&dtrace_lock);

                    if (fmt.dtfd_format == 0 ||
                        fmt.dtfd_format > state->dts_nformats) {
                              mutex_exit(&dtrace_lock);
                              return (EINVAL);
                    }

                    /*
                     * Format strings are allocated contiguously and they are
                     * never freed; if a format index is less than the number
                     * of formats, we can assert that the format map is non-NULL
                     * and that the format for the specified index is non-NULL.
                     */
                    ASSERT(state->dts_formats != NULL);
                    str = state->dts_formats[fmt.dtfd_format - 1];
                    ASSERT(str != NULL);

                    len = strlen(str) + 1;

                    if (len > fmt.dtfd_length) {
                              fmt.dtfd_length = len;

                              if (copyout(&fmt, (void *)arg, sizeof (fmt)) != 0) {
                                        mutex_exit(&dtrace_lock);
                                        return (EINVAL);
                              }
                    } else {
                              if (copyout(str, fmt.dtfd_string, len) != 0) {
                                        mutex_exit(&dtrace_lock);
                                        return (EINVAL);
                              }
                    }

                    mutex_exit(&dtrace_lock);
                    return (0);
          }

          default:
                    break;
          }

          return (ENOTTY);
}

/*ARGSUSED*/
static int
dtrace_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
          dtrace_state_t *state;

          switch (cmd) {
          case DDI_DETACH:
                    break;

          case DDI_SUSPEND:
                    return (DDI_SUCCESS);

          default:
                    return (DDI_FAILURE);
          }

          mutex_enter(&cpu_lock);
          mutex_enter(&dtrace_provider_lock);
          mutex_enter(&dtrace_lock);

          ASSERT(dtrace_opens == 0);

          if (dtrace_helpers > 0) {
                    mutex_exit(&dtrace_provider_lock);
                    mutex_exit(&dtrace_lock);
                    mutex_exit(&cpu_lock);
                    return (DDI_FAILURE);
          }

          if (dtrace_unregister((dtrace_provider_id_t)dtrace_provider) != 0) {
                    mutex_exit(&dtrace_provider_lock);
                    mutex_exit(&dtrace_lock);
                    mutex_exit(&cpu_lock);
                    return (DDI_FAILURE);
          }

          dtrace_provider = NULL;

          if ((state = dtrace_anon_grab()) != NULL) {
                    /*
                     * If there were ECBs on this state, the provider should
                     * have not been allowed to detach; assert that there is
                     * none.
                     */
                    ASSERT(state->dts_necbs == 0);
                    dtrace_state_destroy(state);

                    /*
                     * If we're being detached with anonymous state, we need to
                     * indicate to the kernel debugger that DTrace is now inactive.
                     */
                    (void) kdi_dtrace_set(KDI_DTSET_DTRACE_DEACTIVATE);
          }

          bzero(&dtrace_anon, sizeof (dtrace_anon_t));
          unregister_cpu_setup_func((cpu_setup_func_t *)dtrace_cpu_setup, NULL);
          dtrace_cpu_init = NULL;
          dtrace_helpers_cleanup = NULL;
          dtrace_helpers_fork = NULL;
          dtrace_cpustart_init = NULL;
          dtrace_cpustart_fini = NULL;
          dtrace_debugger_init = NULL;
          dtrace_debugger_fini = NULL;
          dtrace_modload = NULL;
          dtrace_modunload = NULL;

          ASSERT(dtrace_getf == 0);
          ASSERT(dtrace_closef == NULL);

          mutex_exit(&cpu_lock);

          kmem_free(dtrace_probes, dtrace_nprobes * sizeof (dtrace_probe_t *));
          dtrace_probes = NULL;
          dtrace_nprobes = 0;

          dtrace_hash_destroy(dtrace_bymod);
          dtrace_hash_destroy(dtrace_byfunc);
          dtrace_hash_destroy(dtrace_byname);
          dtrace_bymod = NULL;
          dtrace_byfunc = NULL;
          dtrace_byname = NULL;

          kmem_cache_destroy(dtrace_state_cache);
          vmem_destroy(dtrace_minor);
          vmem_destroy(dtrace_arena);

          if (dtrace_toxrange != NULL) {
                    kmem_free(dtrace_toxrange,
                        dtrace_toxranges_max * sizeof (dtrace_toxrange_t));
                    dtrace_toxrange = NULL;
                    dtrace_toxranges = 0;
                    dtrace_toxranges_max = 0;
          }

          ddi_remove_minor_node(dtrace_devi, NULL);
          dtrace_devi = NULL;

          ddi_soft_state_fini(&dtrace_softstate);

          ASSERT(dtrace_vtime_references == 0);
          ASSERT(dtrace_opens == 0);
          ASSERT(dtrace_retained == NULL);

          mutex_exit(&dtrace_lock);
          mutex_exit(&dtrace_provider_lock);

          /*
           * We don't destroy the task queue until after we have dropped our
           * locks (taskq_destroy() may block on running tasks).  To prevent
           * attempting to do work after we have effectively detached but before
           * the task queue has been destroyed, all tasks dispatched via the
           * task queue must check that DTrace is still attached before
           * performing any operation.
           */
          taskq_destroy(dtrace_taskq);
          dtrace_taskq = NULL;

          return (DDI_SUCCESS);
}
#endif

#ifdef illumos
/*ARGSUSED*/
static int
dtrace_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
{
          int error;

          switch (infocmd) {
          case DDI_INFO_DEVT2DEVINFO:
                    *result = (void *)dtrace_devi;
                    error = DDI_SUCCESS;
                    break;
          case DDI_INFO_DEVT2INSTANCE:
                    *result = (void *)0;
                    error = DDI_SUCCESS;
                    break;
          default:
                    error = DDI_FAILURE;
          }
          return (error);
}
#endif

#ifdef illumos
static struct cb_ops dtrace_cb_ops = {
          dtrace_open,                  /* open */
          dtrace_close,                 /* close */
          nulldev,            /* strategy */
          nulldev,            /* print */
          nodev,                        /* dump */
          nodev,                        /* read */
          nodev,                        /* write */
          dtrace_ioctl,                 /* ioctl */
          nodev,                        /* devmap */
          nodev,                        /* mmap */
          nodev,                        /* segmap */
          nochpoll,           /* poll */
          ddi_prop_op,                  /* cb_prop_op */
          0,                            /* streamtab  */
          D_NEW | D_MP                  /* Driver compatibility flag */
};

static struct dev_ops dtrace_ops = {
          DEVO_REV,           /* devo_rev */
          0,                            /* refcnt */
          dtrace_info,                  /* get_dev_info */
          nulldev,            /* identify */
          nulldev,            /* probe */
          dtrace_attach,                /* attach */
          dtrace_detach,                /* detach */
          nodev,                        /* reset */
          &dtrace_cb_ops,               /* driver operations */
          NULL,                         /* bus operations */
          nodev                         /* dev power */
};

static struct modldrv modldrv = {
          &mod_driverops,               /* module type (this is a pseudo driver) */
          "Dynamic Tracing",  /* name of module */
          &dtrace_ops,                  /* driver ops */
};

static struct modlinkage modlinkage = {
          MODREV_1,
          (void *)&modldrv,
          NULL
};

int
_init(void)
{
          return (mod_install(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
          return (mod_info(&modlinkage, modinfop));
}

int
_fini(void)
{
          return (mod_remove(&modlinkage));
}
#endif

#ifdef __FreeBSD__
static d_ioctl_t    dtrace_ioctl;
static d_ioctl_t    dtrace_ioctl_helper;
static void                   dtrace_load(void *);
static int                    dtrace_unload(void);
static struct cdev  *dtrace_dev;
static struct cdev  *helper_dev;

void dtrace_invop_init(void);
void dtrace_invop_uninit(void);

static struct cdevsw dtrace_cdevsw = {
          .d_version          = D_VERSION,
          .d_ioctl  = dtrace_ioctl,
          .d_open             = dtrace_open,
          .d_name             = "dtrace",
};

static struct cdevsw helper_cdevsw = {
          .d_version          = D_VERSION,
          .d_ioctl  = dtrace_ioctl_helper,
          .d_name             = "helper",
};
#endif /* __FreeBSD__ */

#ifdef __NetBSD__
void dtrace_invop_init(void);
void dtrace_invop_uninit(void);

struct dtrace_state_worker {
          kmutex_t lock;
          kcondvar_t cv;
          void (*fn)(dtrace_state_t *);
          dtrace_state_t *state;
          int interval;
          lwp_t *lwp;
          bool exiting;
};

static void
dtrace_state_worker_thread(void *vp)
{
          struct dtrace_state_worker *w = vp;

          mutex_enter(&w->lock);
          while (!w->exiting) {
                    int error;

                    error = cv_timedwait(&w->cv, &w->lock, w->interval);
                    if (error == EWOULDBLOCK) {
                              mutex_exit(&w->lock);
                              w->fn(w->state);
                              mutex_enter(&w->lock);
                    }
          }
          mutex_exit(&w->lock);
          kthread_exit(0);
}

struct dtrace_state_worker *
dtrace_state_worker_add(void (*fn)(dtrace_state_t *), dtrace_state_t *state,
    hrtime_t interval)
{
          struct dtrace_state_worker *w;
          int error __diagused;

          w = kmem_alloc(sizeof(*w), KM_SLEEP);
          mutex_init(&w->lock, "dtrace", MUTEX_DEFAULT, NULL);
          cv_init(&w->cv, "dtrace");
          w->interval = ((uintmax_t)hz * interval) / NANOSEC;
          w->fn = fn;
          w->state = state;
          w->exiting = false;
          error = kthread_create(PRI_NONE, KTHREAD_MPSAFE|KTHREAD_MUSTJOIN, NULL,
              dtrace_state_worker_thread, w, &w->lwp, "dtrace-state-worker");
          KASSERT(error == 0); /* XXX */
          return w;
}

void
dtrace_state_worker_remove(struct dtrace_state_worker *w)
{
          int error __diagused;

          KASSERT(!w->exiting);
          mutex_enter(&w->lock);
          w->exiting = true;
          cv_signal(&w->cv);
          mutex_exit(&w->lock);
          error = kthread_join(w->lwp);
          KASSERT(error == 0);
          cv_destroy(&w->cv);
          mutex_destroy(&w->lock);
          kmem_free(w, sizeof(*w));
}

#endif /* __NetBSD__ */

static void                   dtrace_load(void *);
static int                    dtrace_unload(void);

#include <dtrace_anon.c>
#include <dtrace_ioctl.c>
#include <dtrace_load.c>
#include <dtrace_modevent.c>
#include <dtrace_sysctl.c>
#include <dtrace_unload.c>
#include <dtrace_vtime.c>
#include <dtrace_hacks.c>
#include <dtrace_isa.c>

#ifdef __FreeBSD__
DEV_MODULE(dtrace, dtrace_modevent, NULL);
MODULE_VERSION(dtrace, 1);
MODULE_DEPEND(dtrace, opensolaris, 1, 1, 1);
#endif /* __FreeBSD__ */

#ifdef __NetBSD__
MODULE(MODULE_CLASS_MISC, dtrace, "solaris");
#endif /* __NetBSD__ */