1/*	$NetBSD: makecontext.c,v 1.5 2009/12/14 01:07:42 matt 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("$FreeBSD$");
36#if defined(LIBC_SCCS) && !defined(lint)
37__RCSID("$NetBSD: makecontext.c,v 1.5 2009/12/14 01:07:42 matt Exp $");
38#endif
39
40#include <sys/param.h>
41#include <machine/abi.h>
42#define	_WANT_MIPS_REGNUM
43#include <machine/regnum.h>
44
45#include <stdarg.h>
46#include <stdlib.h>
47#include <unistd.h>
48#include <stdio.h>
49#include <ucontext.h>
50
51__weak_reference(__makecontext, makecontext);
52
53void _ctx_done(ucontext_t *);
54void _ctx_start(void);
55
56void
57__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
58{
59	mcontext_t *mc;
60	register_t *sp;
61	int i;
62	va_list ap;
63
64	/*
65	 * XXX/juli
66	 * We need an mc_len or mc_flags like other architectures
67	 * so that we can mark a context as invalid.  Store it in
68	 * mc->mc_regs[ZERO] perhaps?
69	 */
70	if (argc < 0 || ucp == NULL ||
71	    ucp->uc_stack.ss_sp == NULL ||
72	    ucp->uc_stack.ss_size < MINSIGSTKSZ)
73		return;
74	mc = &ucp->uc_mcontext;
75
76	sp  = (register_t *)
77	    ((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
78#if defined(__mips_o32) || defined(__mips_o64)
79	sp -= (argc >= 4 ? argc : 4);	/* Make room for >=4 arguments. */
80#elif defined(__mips_n32) || defined(__mips_n64)
81	sp -= (argc > 8 ? argc - 8 : 0); /* Make room for > 8 arguments. */
82#endif
83	sp  = (register_t *)((uintptr_t)sp & ~(STACK_ALIGN - 1));
84
85	mc->mc_regs[SP] = (intptr_t)sp;
86	mc->mc_regs[S0] = (intptr_t)ucp;
87	mc->mc_regs[T9] = (intptr_t)func;
88	mc->mc_pc = (intptr_t)_ctx_start;
89
90	/* Construct argument list. */
91	va_start(ap, argc);
92#if defined(__mips_o32) || defined(__mips_o64)
93	/* Up to the first four arguments are passed in $a0-3. */
94	for (i = 0; i < argc && i < 4; i++)
95		/* LINTED register_t is safe */
96		mc->mc_regs[A0 + i] = va_arg(ap, register_t);
97	/* Skip over the $a0-3 gap. */
98	sp += 4;
99#endif
100#if defined(__mips_n32) || defined(__mips_n64)
101	/* Up to the first 8 arguments are passed in $a0-7. */
102	for (i = 0; i < argc && i < 8; i++)
103		/* LINTED register_t is safe */
104		mc->mc_regs[A0 + i] = va_arg(ap, register_t);
105#endif
106	/* Pass remaining arguments on the stack. */
107	for (; i < argc; i++)
108		/* LINTED register_t is safe */
109		*sp++ = va_arg(ap, register_t);
110	va_end(ap);
111}
112
113void
114_ctx_done(ucontext_t *ucp)
115{
116
117	if (ucp->uc_link == NULL)
118		exit(0);
119	else {
120		setcontext((const ucontext_t *)ucp->uc_link);
121		abort();
122	}
123}
124