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 *
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__FBSDID("$FreeBSD$");
34
35#include <stdlib.h>
36#include <stddef.h>
37#include <inttypes.h>
38#include <ucontext.h>
39
40#include <stdarg.h>
41
42extern void _ctx_start(void);
43
44void
45ctx_done(ucontext_t *ucp)
46{
47
48	if (ucp->uc_link == NULL)
49		exit(0);
50	else {
51		setcontext((const ucontext_t *)ucp->uc_link);
52		abort();
53	}
54}
55
56__weak_reference(__makecontext, makecontext);
57
58void
59__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
60{
61	__greg_t *gr = ucp->uc_mcontext.__gregs;
62	int i;
63	unsigned int *sp;
64	va_list ap;
65
66	/* Compute and align stack pointer. */
67	sp = (unsigned int *)
68	    (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size -
69	      sizeof(double)) & ~7);
70	/* Allocate necessary stack space for arguments exceeding r0-3. */
71	if (argc > 4)
72		sp -= argc - 4;
73	gr[_REG_SP] = (__greg_t)sp;
74	/* Wipe out frame pointer. */
75	gr[_REG_FP] = 0;
76	/* Arrange for return via the trampoline code. */
77	gr[_REG_PC] = (__greg_t)_ctx_start;
78	gr[_REG_R4] = (__greg_t)func;
79	gr[_REG_R5] = (__greg_t)ucp;
80
81	va_start(ap, argc);
82	/* Pass up to four arguments in r0-3. */
83	for (i = 0; i < argc && i < 4; i++)
84		gr[_REG_R0 + i] = va_arg(ap, int);
85	/* Pass any additional arguments on the stack. */
86	for (argc -= i; argc > 0; argc--)
87		*sp++ = va_arg(ap, int);
88	va_end(ap);
89}
90