1 /* $NetBSD: _lwp.c,v 1.11 2025/04/25 01:18:24 riastradh Exp $ */
2
3 /*
4 * Copyright (c) 2001 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Wayne Knowles
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 #if defined(LIBC_SCCS) && !defined(lint)
34 __RCSID("$NetBSD: _lwp.c,v 1.11 2025/04/25 01:18:24 riastradh Exp $");
35 #endif /* LIBC_SCCS and not lint */
36
37 #include "namespace.h"
38
39 #include <sys/param.h>
40 #include <sys/types.h>
41
42 #include <lwp.h>
43 #include <stdlib.h>
44 #include <ucontext.h>
45
46 #include <machine/lwp_private.h>
47
48 #if defined(__mips_o32) || defined(__mips_o64)
49 #define CALLFRAME_SIZ (6 * sizeof(void *))
50 #else
51 #define CALLFRAME_SIZ (4 * sizeof(uint64_t))
52 #endif
53
54 void
_lwp_makecontext(ucontext_t * u,void (* start)(void *),void * arg,void * tcb,caddr_t stack_base,size_t stack_size)55 _lwp_makecontext(ucontext_t *u, void (*start)(void *),
56 void *arg, void *tcb, caddr_t stack_base, size_t stack_size)
57 {
58 caddr_t sp;
59 __greg_t *gr;
60
61 getcontext(u);
62 gr = u->uc_mcontext.__gregs;
63 u->uc_link = NULL;
64
65 u->uc_stack.ss_sp = stack_base;
66 u->uc_stack.ss_size = stack_size;
67 sp = stack_base + stack_size - CALLFRAME_SIZ;
68
69 gr[_REG_EPC] = (uintptr_t) start;
70 gr[_REG_T9] = (uintptr_t) start; /* required for .abicalls */
71 gr[_REG_RA] = (uintptr_t) _lwp_exit;
72 gr[_REG_A0] = (uintptr_t) arg;
73 gr[_REG_SP] = (uintptr_t) sp & ~STACK_ALIGNBYTES;
74 u->uc_mcontext._mc_tlsbase =
75 (uintptr_t)tcb + TLS_TP_OFFSET + sizeof(struct tls_tcb);
76 u->uc_flags |= _UC_TLSBASE;
77 }
78