makecontext.c revision 330897 
1/*	$NetBSD: makecontext.c,v 1.2 2003/01/18 11:06:24 thorpej Exp $	*/
2
3/*-
4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD
5 *
6 * Copyright (c) 2001 The NetBSD Foundation, Inc.
7 * All rights reserved.
8 *
9 * This code is derived from software contributed to The NetBSD Foundation
10 * by Klaus Klein.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 *    notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 *    notice, this list of conditions and the following disclaimer in the
19 *    documentation and/or other materials provided with the distribution.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
23 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
25 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 * POSSIBILITY OF SUCH DAMAGE.
32 */
33
34#include <sys/cdefs.h>
35__FBSDID("$FreeBSD: stable/11/lib/libc/arm/gen/makecontext.c 330897 2018-03-14 03:19:51Z eadler $");
36
37#include <stdlib.h>
38#include <stddef.h>
39#include <inttypes.h>
40#include <ucontext.h>
41
42#include <stdarg.h>
43
44extern void _ctx_start(void);
45
46void
47ctx_done(ucontext_t *ucp)
48{
49
50	if (ucp->uc_link == NULL)
51		exit(0);
52	else {
53		setcontext((const ucontext_t *)ucp->uc_link);
54		abort();
55	}
56}
57
58__weak_reference(__makecontext, makecontext);
59
60void
61__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
62{
63	__greg_t *gr = ucp->uc_mcontext.__gregs;
64	int i;
65	unsigned int *sp;
66	va_list ap;
67
68	/* Compute and align stack pointer. */
69	sp = (unsigned int *)
70	    (((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size -
71	      sizeof(double)) & ~7);
72	/* Allocate necessary stack space for arguments exceeding r0-3. */
73	if (argc > 4)
74		sp -= argc - 4;
75	gr[_REG_SP] = (__greg_t)sp;
76	/* Wipe out frame pointer. */
77	gr[_REG_FP] = 0;
78	/* Arrange for return via the trampoline code. */
79	gr[_REG_PC] = (__greg_t)_ctx_start;
80	gr[_REG_R4] = (__greg_t)func;
81	gr[_REG_R5] = (__greg_t)ucp;
82
83	va_start(ap, argc);
84	/* Pass up to four arguments in r0-3. */
85	for (i = 0; i < argc && i < 4; i++)
86		gr[_REG_R0 + i] = va_arg(ap, int);
87	/* Pass any additional arguments on the stack. */
88	for (argc -= i; argc > 0; argc--)
89		*sp++ = va_arg(ap, int);
90	va_end(ap);
91}
92