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 /*
23 * Copyright 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 /* Copyright (c) 1988 AT&T */
28 /* All Rights Reserved */
29
30 #pragma ident "%Z%%M% %I% %E% SMI"
31
32 #pragma weak _makecontext = makecontext
33
34 #include "lint.h"
35 #include <stdarg.h>
36 #include <ucontext.h>
37 #include <sys/stack.h>
38
39 /*
40 * The ucontext_t that the user passes in must have been primed with a
41 * call to getcontext(2), have the uc_stack member set to reflect the
42 * stack which this context will use, and have the uc_link member set
43 * to the context which should be resumed when this context returns.
44 * When makecontext() returns, the ucontext_t will be set to run the
45 * given function with the given parameters on the stack specified by
46 * uc_stack, and which will return to the ucontext_t specified by uc_link.
47 */
48
49 static void resumecontext(void);
50
51 void
makecontext(ucontext_t * ucp,void (* func)(),int argc,...)52 makecontext(ucontext_t *ucp, void (*func)(), int argc, ...)
53 {
54 long *sp;
55 long *tsp;
56 va_list ap;
57 size_t size;
58
59 ucp->uc_mcontext.gregs[EIP] = (greg_t)func;
60
61 size = sizeof (long) * (argc + 1);
62
63 sp = (long *)(((uintptr_t)ucp->uc_stack.ss_sp +
64 ucp->uc_stack.ss_size - size) & ~(STACK_ALIGN - 1));
65
66 tsp = sp + 1;
67
68 va_start(ap, argc);
69
70 while (argc-- > 0) {
71 *tsp++ = va_arg(ap, long);
72 }
73
74 va_end(ap);
75
76 *sp = (long)resumecontext; /* return address */
77
78 ucp->uc_mcontext.gregs[UESP] = (greg_t)sp;
79 }
80
81
82 static void
resumecontext(void)83 resumecontext(void)
84 {
85 ucontext_t uc;
86
87 (void) getcontext(&uc);
88 (void) setcontext(uc.uc_link);
89 }
90