makecontext.c revision 1.4 
1/*	$NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:57 martin 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#if defined(LIBC_SCCS) && !defined(lint)
34__RCSID("$NetBSD: makecontext.c,v 1.4 2008/04/28 20:22:57 martin Exp $");
35#endif
36
37#include <inttypes.h>
38#include <stddef.h>
39#include <sys/types.h>
40#include <ucontext.h>
41#include "extern.h"
42
43#include <stdarg.h>
44
45void
46makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
47{
48	__greg_t *gr = ucp->uc_mcontext.__gregs;
49	int i;
50	ulong *sp;
51	va_list ap;
52
53	sp = (ulong *)((caddr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
54	/* Align on quad-word boundary. */
55	sp = (ulong *)((ulong)sp & ~0xf);
56
57	/* Make room for: argx, argd, struct return pointer(?), rwindow. */
58	sp -= (argc > 6 ? argc - 6 : 0) + 6 + 8 + 8;
59
60	va_start(ap, argc);
61
62	/* Pass up to 6 arguments in %o0-5. */
63	for (i = 0; i < argc && i < 6; i++)
64		gr[_REG_O0 + i] = sp[i + 16] = va_arg(ap, unsigned long);
65
66	/* Pass any additional arguments on the stack. */
67	for (; i < argc; i++)
68		sp[i + 16] = va_arg(ap, unsigned long);
69	va_end(ap);
70
71	sp[14] = (ulong)sp - 2047;
72	sp[15] = (ulong)_resumecontext - 8;
73
74	sp = (ulong *)((caddr_t)sp - 2047);
75
76	gr[_REG_O6] = (__greg_t)sp;
77	gr[_REG_PC] = (__greg_t)func;
78	gr[_REG_nPC] = (__greg_t)func + 4;
79	gr[_REG_O7] = (__greg_t)_resumecontext - 8;
80
81}
82