makecontext.c revision 137286 
1/*	$NetBSD: makecontext.c,v 1.2 2003/01/18 11:06:24 thorpej 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 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 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *        This product includes software developed by the NetBSD
21 *        Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 *    contributors may be used to endorse or promote products derived
24 *    from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39#include <sys/cdefs.h>
40__FBSDID("$FreeBSD: head/lib/libc/arm/gen/makecontext.c 137286 2004-11-05 23:53:02Z cognet $");
41
42#include <stdlib.h>
43#include <stddef.h>
44#include <inttypes.h>
45#include <ucontext.h>
46
47#include <stdarg.h>
48
49extern void _ctx_start(void);
50
51void
52ctx_done(ucontext_t *ucp)
53{
54
55	if (ucp->uc_link == NULL)
56		exit(0);
57	else {
58		setcontext((const ucontext_t *)ucp->uc_link);
59		abort();
60	}
61}
62
63__weak_reference(__makecontext, makecontext);
64
65void
66__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
67{
68	__greg_t *gr = ucp->uc_mcontext.__gregs;
69	int i;
70	unsigned int *sp;
71	va_list ap;
72
73	/* Compute and align stack pointer. */
74	sp = (unsigned int *)
75	    (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size -
76	      sizeof(double)) & ~7);
77	/* Allocate necessary stack space for arguments exceeding r0-3. */
78	if (argc > 4)
79		sp -= argc - 4;
80	gr[_REG_SP] = (__greg_t)sp;
81	/* Wipe out frame pointer. */
82	gr[_REG_FP] = 0;
83	/* Arrange for return via the trampoline code. */
84	gr[_REG_PC] = (__greg_t)_ctx_start;
85	gr[_REG_R4] = (__greg_t)func;
86	gr[_REG_R5] = (__greg_t)ucp;
87
88	va_start(ap, argc);
89	/* Pass up to four arguments in r0-3. */
90	for (i = 0; i < argc && i < 4; i++)
91		gr[_REG_R0 + i] = va_arg(ap, int);
92	/* Pass any additional arguments on the stack. */
93	for (argc -= i; argc > 0; argc--)
94		*sp++ = va_arg(ap, int);
95	va_end(ap);
96}
97