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