1 /* $NetBSD: makecontext.c,v 1.5 2009/12/14 01:07:42 matt Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD
5 *
6 * Copyright (c) 2001 The NetBSD Foundation, Inc.
7 * All rights reserved.
8 *
9 * This code is derived from software contributed to The NetBSD Foundation
10 * by Klaus Klein.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
23 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 * POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36 #if defined(LIBC_SCCS) && !defined(lint)
37 __RCSID("$NetBSD: makecontext.c,v 1.5 2009/12/14 01:07:42 matt Exp $");
38 #endif
39
40 #include <sys/param.h>
41 #include <machine/abi.h>
42 #define _WANT_MIPS_REGNUM
43 #include <machine/regnum.h>
44
45 #include <stdarg.h>
46 #include <stdlib.h>
47 #include <unistd.h>
48 #include <stdio.h>
49 #include <ucontext.h>
50
51 __weak_reference(__makecontext, makecontext);
52
53 void _ctx_done(ucontext_t *);
54 void _ctx_start(void);
55
56 void
__makecontext(ucontext_t * ucp,void (* func)(void),int argc,...)57 __makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
58 {
59 mcontext_t *mc;
60 register_t *sp;
61 int i;
62 va_list ap;
63
64 /*
65 * XXX/juli
66 * We need an mc_len or mc_flags like other architectures
67 * so that we can mark a context as invalid. Store it in
68 * mc->mc_regs[ZERO] perhaps?
69 */
70 if (argc < 0 || ucp == NULL ||
71 ucp->uc_stack.ss_sp == NULL ||
72 ucp->uc_stack.ss_size < MINSIGSTKSZ)
73 return;
74 mc = &ucp->uc_mcontext;
75
76 sp = (register_t *)
77 ((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
78 #if defined(__mips_o32) || defined(__mips_o64)
79 sp -= (argc >= 4 ? argc : 4); /* Make room for >=4 arguments. */
80 #elif defined(__mips_n32) || defined(__mips_n64)
81 sp -= (argc > 8 ? argc - 8 : 0); /* Make room for > 8 arguments. */
82 #endif
83 sp = (register_t *)((uintptr_t)sp & ~(STACK_ALIGN - 1));
84
85 mc->mc_regs[SP] = (intptr_t)sp;
86 mc->mc_regs[S0] = (intptr_t)ucp;
87 mc->mc_regs[T9] = (intptr_t)func;
88 mc->mc_pc = (intptr_t)_ctx_start;
89
90 /* Construct argument list. */
91 va_start(ap, argc);
92 #if defined(__mips_o32) || defined(__mips_o64)
93 /* Up to the first four arguments are passed in $a0-3. */
94 for (i = 0; i < argc && i < 4; i++)
95 /* LINTED register_t is safe */
96 mc->mc_regs[A0 + i] = va_arg(ap, register_t);
97 /* Skip over the $a0-3 gap. */
98 sp += 4;
99 #endif
100 #if defined(__mips_n32) || defined(__mips_n64)
101 /* Up to the first 8 arguments are passed in $a0-7. */
102 for (i = 0; i < argc && i < 8; i++)
103 /* LINTED register_t is safe */
104 mc->mc_regs[A0 + i] = va_arg(ap, register_t);
105 #endif
106 /* Pass remaining arguments on the stack. */
107 for (; i < argc; i++)
108 /* LINTED register_t is safe */
109 *sp++ = va_arg(ap, register_t);
110 va_end(ap);
111 }
112
113 void
_ctx_done(ucontext_t * ucp)114 _ctx_done(ucontext_t *ucp)
115 {
116
117 if (ucp->uc_link == NULL)
118 exit(0);
119 else {
120 setcontext((const ucontext_t *)ucp->uc_link);
121 abort();
122 }
123 }
124