1 /* $NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:56 martin Exp $ */
2
3 /*-
4 * Copyright (c) 1999 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Klaus Klein.
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: makecontext.c,v 1.4 2008/04/28 20:22:56 martin Exp $");
35 #endif
36
37 #include <inttypes.h>
38 #include <stddef.h>
39 #include <ucontext.h>
40 #include "extern.h"
41
42 #if __STDC__
43 #include <stdarg.h>
44 #else
45 #include <varargs.h>
46 #endif
47
48
49 void
50 #if __STDC__
makecontext(ucontext_t * ucp,void (* func)(void),int argc,...)51 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
52 #else
53 makecontext(ucp, func, argc, va_alist)
54 ucontext_t *ucp;
55 void (*func)();
56 int argc;
57 va_dcl
58 #endif
59 {
60 __greg_t *gr = ucp->uc_mcontext.__gregs;
61 unsigned int *sp;
62 va_list ap;
63
64 /* LINTED __greg_t is safe */
65 gr[_REG_EIP] = (__greg_t)func;
66
67 /* LINTED uintptr_t is safe */
68 sp = (unsigned int *)((uintptr_t)ucp->uc_stack.ss_sp +
69 ucp->uc_stack.ss_size);
70 /* Align on word boundary. */
71 /* LINTED uintptr_t is safe */
72 sp = (unsigned int *)((uintptr_t)sp & ~0x3);
73 sp -= argc + 1; /* Make room for ret and args. */
74 /* LINTED __greg_t is safe */
75 gr[_REG_UESP] = (__greg_t)sp;
76 gr[_REG_EBP] = (__greg_t)0; /* Wipe out frame pointer. */
77
78 /* Put return address on top of stack. */
79 /* LINTED uintptr_t is safe */
80 *sp++ = (uintptr_t)_resumecontext;
81
82 /* Construct argument list. */
83 #if __STDC__
84 va_start(ap, argc);
85 #else
86 va_start(ap);
87 #endif
88 while (argc-- > 0) {
89 /* LINTED uintptr_t is safe */
90 *sp++ = va_arg(ap, uintptr_t);
91 }
92 va_end(ap);
93 }
94