xref: /freebsd/lib/libc/arm/gen/makecontext.c (revision da5432eda807c4b7232d030d5157d5b417ea4f52)
1 /*	$NetBSD: makecontext.c,v 1.2 2003/01/18 11:06:24 thorpej Exp $	*/
2 
3 /*-
4  * SPDX-License-Identifier: BSD-2-Clause
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 #include <stdlib.h>
36 #include <stddef.h>
37 #include <inttypes.h>
38 #include <ucontext.h>
39 
40 #include <stdarg.h>
41 
42 extern void _ctx_start(void);
43 
44 void
45 ctx_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 
58 void
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