xref: /onnv-gate/usr/src/lib/libc/i386/gen/makectxt.c (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24*0Sstevel@tonic-gate  * Use is subject to license terms.
25*0Sstevel@tonic-gate  */
26*0Sstevel@tonic-gate 
27*0Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate /*	Copyright (c) 1988 AT&T	*/
30*0Sstevel@tonic-gate /*	  All Rights Reserved  	*/
31*0Sstevel@tonic-gate 
32*0Sstevel@tonic-gate 
33*0Sstevel@tonic-gate #pragma weak makecontext = _makecontext
34*0Sstevel@tonic-gate 
35*0Sstevel@tonic-gate #include "synonyms.h"
36*0Sstevel@tonic-gate #include <stdarg.h>
37*0Sstevel@tonic-gate #include <ucontext.h>
38*0Sstevel@tonic-gate #include <sys/stack.h>
39*0Sstevel@tonic-gate 
40*0Sstevel@tonic-gate /*
41*0Sstevel@tonic-gate  * The ucontext_t that the user passes in must have been primed with a
42*0Sstevel@tonic-gate  * call to getcontext(2), have the uc_stack member set to reflect the
43*0Sstevel@tonic-gate  * stack which this context will use, and have the uc_link member set
44*0Sstevel@tonic-gate  * to the context which should be resumed when this context returns.
45*0Sstevel@tonic-gate  * When makecontext() returns, the ucontext_t will be set to run the
46*0Sstevel@tonic-gate  * given function with the given parameters on the stack specified by
47*0Sstevel@tonic-gate  * uc_stack, and which will return to the ucontext_t specified by uc_link.
48*0Sstevel@tonic-gate  */
49*0Sstevel@tonic-gate 
50*0Sstevel@tonic-gate static void resumecontext(void);
51*0Sstevel@tonic-gate 
52*0Sstevel@tonic-gate void
53*0Sstevel@tonic-gate makecontext(ucontext_t *ucp, void (*func)(), int argc, ...)
54*0Sstevel@tonic-gate {
55*0Sstevel@tonic-gate 	long *sp;
56*0Sstevel@tonic-gate 	long *tsp;
57*0Sstevel@tonic-gate 	va_list ap;
58*0Sstevel@tonic-gate 	size_t size;
59*0Sstevel@tonic-gate 
60*0Sstevel@tonic-gate 	ucp->uc_mcontext.gregs[EIP] = (greg_t)func;
61*0Sstevel@tonic-gate 
62*0Sstevel@tonic-gate 	size = sizeof (long) * (argc + 1);
63*0Sstevel@tonic-gate 
64*0Sstevel@tonic-gate 	sp = (long *)(((uintptr_t)ucp->uc_stack.ss_sp +
65*0Sstevel@tonic-gate 	    ucp->uc_stack.ss_size - size) & ~(STACK_ALIGN - 1));
66*0Sstevel@tonic-gate 
67*0Sstevel@tonic-gate 	tsp = sp + 1;
68*0Sstevel@tonic-gate 
69*0Sstevel@tonic-gate 	va_start(ap, argc);
70*0Sstevel@tonic-gate 
71*0Sstevel@tonic-gate 	while (argc-- > 0) {
72*0Sstevel@tonic-gate 		*tsp++ = va_arg(ap, long);
73*0Sstevel@tonic-gate 	}
74*0Sstevel@tonic-gate 
75*0Sstevel@tonic-gate 	va_end(ap);
76*0Sstevel@tonic-gate 
77*0Sstevel@tonic-gate 	*sp = (long)resumecontext;		/* return address */
78*0Sstevel@tonic-gate 
79*0Sstevel@tonic-gate 	ucp->uc_mcontext.gregs[UESP] = (greg_t)sp;
80*0Sstevel@tonic-gate }
81*0Sstevel@tonic-gate 
82*0Sstevel@tonic-gate 
83*0Sstevel@tonic-gate static void
84*0Sstevel@tonic-gate resumecontext(void)
85*0Sstevel@tonic-gate {
86*0Sstevel@tonic-gate 	ucontext_t uc;
87*0Sstevel@tonic-gate 
88*0Sstevel@tonic-gate 	(void) getcontext(&uc);
89*0Sstevel@tonic-gate 	(void) setcontext(uc.uc_link);
90*0Sstevel@tonic-gate }
91