makecontext.c revision 1.3 
1/*	$NetBSD: makecontext.c,v 1.3 2006/05/11 00:34:44 mrg 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 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *        This product includes software developed by the NetBSD
21 *        Foundation, Inc. and its contributors.
22 * 4. Neither the name of The NetBSD Foundation nor the names of its
23 *    contributors may be used to endorse or promote products derived
24 *    from this software without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36 * POSSIBILITY OF SUCH DAMAGE.
37 */
38
39#include <sys/cdefs.h>
40#if defined(LIBC_SCCS) && !defined(lint)
41__RCSID("$NetBSD: makecontext.c,v 1.3 2006/05/11 00:34:44 mrg Exp $");
42#endif
43
44#include <inttypes.h>
45#include <stddef.h>
46#include <sys/types.h>
47#include <ucontext.h>
48#include "extern.h"
49
50#include <stdarg.h>
51
52void
53makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
54{
55	__greg_t *gr = ucp->uc_mcontext.__gregs;
56	int i;
57	ulong *sp;
58	va_list ap;
59
60	sp = (ulong *)((caddr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
61	/* Align on quad-word boundary. */
62	sp = (ulong *)((ulong)sp & ~0xf);
63
64	/* Make room for: argx, argd, struct return pointer(?), rwindow. */
65	sp -= (argc > 6 ? argc - 6 : 0) + 6 + 8 + 8;
66
67	va_start(ap, argc);
68
69	/* Pass up to 6 arguments in %o0-5. */
70	for (i = 0; i < argc && i < 6; i++)
71		gr[_REG_O0 + i] = sp[i + 16] = va_arg(ap, unsigned long);
72
73	/* Pass any additional arguments on the stack. */
74	for (; i < argc; i++)
75		sp[i + 16] = va_arg(ap, unsigned long);
76	va_end(ap);
77
78	sp[14] = (ulong)sp - 2047;
79	sp[15] = (ulong)_resumecontext - 8;
80
81	sp = (ulong *)((caddr_t)sp - 2047);
82
83	gr[_REG_O6] = (__greg_t)sp;
84	gr[_REG_PC] = (__greg_t)func;
85	gr[_REG_nPC] = (__greg_t)func + 4;
86	gr[_REG_O7] = (__greg_t)_resumecontext - 8;
87
88}
89