1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
23 * Copyright 2013 Voxer Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include <unistd.h>
28 #include <fcntl.h>
29 #include <dlfcn.h>
30 #include <link.h>
31 #include <sys/dtrace.h>
32
33 #include <stdarg.h>
34 #include <stdio.h>
35 #include <stdlib.h>
36 #include <string.h>
37 #include <errno.h>
38 #include <libelf.h>
39
40 /*
41 * In Solaris 10 GA, the only mechanism for communicating helper information
42 * is through the DTrace helper pseudo-device node in /devices; there is
43 * no /dev link. Because of this, USDT providers and helper actions don't
44 * work inside of non-global zones. This issue was addressed by adding
45 * the /dev and having this initialization code use that /dev link. If the
46 * /dev link doesn't exist it falls back to looking for the /devices node
47 * as this code may be embedded in a binary which runs on Solaris 10 GA.
48 *
49 * Users may set the following environment variable to affect the way
50 * helper initialization takes place:
51 *
52 * DTRACE_DOF_INIT_DEBUG enable debugging output
53 * DTRACE_DOF_INIT_DISABLE disable helper loading
54 * DTRACE_DOF_INIT_DEVNAME set the path to the helper node
55 */
56
57 static const char *devnamep = "/dev/dtrace/helper";
58 #ifdef illumos
59 static const char *olddevname = "/devices/pseudo/dtrace@0:helper";
60 #endif
61
62 static const char *modname; /* Name of this load object */
63 static int gen; /* DOF helper generation */
64 extern dof_hdr_t __SUNW_dof; /* DOF defined in the .SUNW_dof section */
65 static boolean_t dof_init_debug = B_FALSE; /* From DTRACE_DOF_INIT_DEBUG */
66
67 static void
dprintf(int debug,const char * fmt,...)68 dprintf(int debug, const char *fmt, ...)
69 {
70 va_list ap;
71
72 if (debug && !dof_init_debug)
73 return;
74
75 va_start(ap, fmt);
76
77 if (modname == NULL)
78 (void) fprintf(stderr, "dtrace DOF: ");
79 else
80 (void) fprintf(stderr, "dtrace DOF %s: ", modname);
81
82 (void) vfprintf(stderr, fmt, ap);
83
84 if (fmt[strlen(fmt) - 1] != '\n')
85 (void) fprintf(stderr, ": %s\n", strerror(errno));
86
87 va_end(ap);
88 }
89
90 #ifdef illumos
91 #pragma init(dtrace_dof_init)
92 #else
93 static void dtrace_dof_init(void) __attribute__ ((constructor));
94 #endif
95
96 static void
dtrace_dof_init(void)97 dtrace_dof_init(void)
98 {
99 dof_hdr_t *dof = &__SUNW_dof;
100 #ifdef _LP64
101 Elf64_Ehdr *elf;
102 #else
103 Elf32_Ehdr *elf;
104 #endif
105 dof_helper_t dh;
106 Link_map *lmp = NULL;
107 #ifdef illumos
108 Lmid_t lmid;
109 #else
110 u_long lmid = 0;
111 #endif
112 int fd;
113 const char *p;
114
115 if (getenv("DTRACE_DOF_INIT_DISABLE") != NULL)
116 return;
117
118 if (getenv("DTRACE_DOF_INIT_DEBUG") != NULL)
119 dof_init_debug = B_TRUE;
120
121 if (dlinfo(RTLD_SELF, RTLD_DI_LINKMAP, &lmp) == -1 || lmp == NULL) {
122 dprintf(1, "couldn't discover module name or address\n");
123 return;
124 }
125
126 #ifdef illumos
127 if (dlinfo(RTLD_SELF, RTLD_DI_LMID, &lmid) == -1) {
128 dprintf(1, "couldn't discover link map ID\n");
129 return;
130 }
131 #endif
132
133 if ((modname = strrchr(lmp->l_name, '/')) == NULL)
134 modname = lmp->l_name;
135 else
136 modname++;
137
138 if (dof->dofh_ident[DOF_ID_MAG0] != DOF_MAG_MAG0 ||
139 dof->dofh_ident[DOF_ID_MAG1] != DOF_MAG_MAG1 ||
140 dof->dofh_ident[DOF_ID_MAG2] != DOF_MAG_MAG2 ||
141 dof->dofh_ident[DOF_ID_MAG3] != DOF_MAG_MAG3) {
142 dprintf(0, ".SUNW_dof section corrupt\n");
143 return;
144 }
145
146 elf = (void *)lmp->l_addr;
147
148 dh.dofhp_dof = (uintptr_t)dof;
149 dh.dofhp_addr = elf->e_type == ET_DYN ? (uintptr_t) lmp->l_addr : 0;
150 #ifdef __FreeBSD__
151 dh.dofhp_pid = getpid();
152 #endif
153
154 if (lmid == 0) {
155 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
156 "%s", modname);
157 } else {
158 (void) snprintf(dh.dofhp_mod, sizeof (dh.dofhp_mod),
159 "LM%lu`%s", lmid, modname);
160 }
161
162 if ((p = getenv("DTRACE_DOF_INIT_DEVNAME")) != NULL)
163 devnamep = p;
164
165 if ((fd = open64(devnamep, O_RDWR)) < 0) {
166 dprintf(1, "failed to open helper device %s", devnamep);
167 #ifdef illumos
168 /*
169 * If the device path wasn't explicitly set, try again with
170 * the old device path.
171 */
172 if (p != NULL)
173 return;
174
175 devnamep = olddevname;
176
177 if ((fd = open64(devnamep, O_RDWR)) < 0) {
178 dprintf(1, "failed to open helper device %s", devnamep);
179 return;
180 }
181 #else
182 return;
183 #endif
184 }
185 if ((gen = ioctl(fd, DTRACEHIOC_ADDDOF, &dh)) == -1)
186 dprintf(1, "DTrace ioctl failed for DOF at %p", dof);
187 else {
188 dprintf(1, "DTrace ioctl succeeded for DOF at %p\n", dof);
189 #ifdef __FreeBSD__
190 gen = dh.dofhp_gen;
191 #endif
192 }
193
194 (void) close(fd);
195 }
196
197 #ifdef illumos
198 #pragma fini(dtrace_dof_fini)
199 #else
200 static void dtrace_dof_fini(void) __attribute__ ((destructor));
201 #endif
202
203 static void
dtrace_dof_fini(void)204 dtrace_dof_fini(void)
205 {
206 int fd;
207
208 if ((fd = open64(devnamep, O_RDWR)) < 0) {
209 dprintf(1, "failed to open helper device %s", devnamep);
210 return;
211 }
212
213 if ((gen = ioctl(fd, DTRACEHIOC_REMOVE, &gen)) == -1)
214 dprintf(1, "DTrace ioctl failed to remove DOF (%d)\n", gen);
215 else
216 dprintf(1, "DTrace ioctl removed DOF (%d)\n", gen);
217
218 (void) close(fd);
219 }
220