makecontext.c revision 330897 
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: stable/11/lib/libc/mips/gen/makecontext.c 330897 2018-03-14 03:19:51Z eadler $");
36#if defined(LIBC_SCCS) && !defined(lint)
37__RCSID("$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/regnum.h>
42
43#include <stdarg.h>
44#include <stdlib.h>
45#include <unistd.h>
46#include <stdio.h>
47#include <ucontext.h>
48
49__weak_reference(__makecontext, makecontext);
50
51void _ctx_done(ucontext_t *);
52void _ctx_start(void);
53
54void
55__makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
56{
57	mcontext_t *mc;
58	register_t *sp;
59	int i;
60	va_list ap;
61
62	/*
63	 * XXX/juli
64	 * We need an mc_len or mc_flags like other architectures
65	 * so that we can mark a context as invalid.  Store it in
66	 * mc->mc_regs[ZERO] perhaps?
67	 */
68	if (argc < 0 || argc > 6 || ucp == NULL ||
69	    ucp->uc_stack.ss_sp == NULL ||
70	    ucp->uc_stack.ss_size < MINSIGSTKSZ)
71		return;
72	mc = &ucp->uc_mcontext;
73
74	sp  = (register_t *)
75	    ((uintptr_t)ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
76#if defined(__mips_o32) || defined(__mips_o64)
77	sp -= (argc >= 4 ? argc : 4);	/* Make room for >=4 arguments. */
78	sp  = (register_t *)
79	    ((uintptr_t)sp & ~0x7);	/* Align on double-word boundary. */
80#elif defined(__mips_n32) || defined(__mips_n64)
81	sp -= (argc > 8 ? argc - 8 : 0); /* Make room for > 8 arguments. */
82	sp  = (register_t *)
83	    ((uintptr_t)sp & ~0xf);	/* Align on quad-word boundary. */
84#endif
85
86	mc->mc_regs[SP] = (intptr_t)sp;
87	mc->mc_regs[S0] = (intptr_t)ucp;
88	mc->mc_regs[T9] = (intptr_t)func;
89	mc->mc_pc = (intptr_t)_ctx_start;
90
91	/* Construct argument list. */
92	va_start(ap, argc);
93#if defined(__mips_o32) || defined(__mips_o64)
94	/* Up to the first four arguments are passed in $a0-3. */
95	for (i = 0; i < argc && i < 4; i++)
96		/* LINTED register_t is safe */
97		mc->mc_regs[A0 + i] = va_arg(ap, register_t);
98	/* Pass remaining arguments on the stack above the $a0-3 gap. */
99	sp += i;
100#endif
101#if defined(__mips_n32) || defined(__mips_n64)
102	/* Up to the first 8 arguments are passed in $a0-7. */
103	for (i = 0; i < argc && i < 8; i++)
104		/* LINTED register_t is safe */
105		mc->mc_regs[A0 + i] = va_arg(ap, register_t);
106	/* Pass remaining arguments on the stack above the $a0-3 gap. */
107#endif
108	/* Pass remaining arguments on the stack above the $a0-3 gap. */
109	for (; i < argc; i++)
110		/* LINTED uintptr_t is safe */
111		*sp++ = va_arg(ap, register_t);
112	va_end(ap);
113}
114
115void
116_ctx_done(ucontext_t *ucp)
117{
118
119	if (ucp->uc_link == NULL)
120		exit(0);
121	else {
122		setcontext((const ucontext_t *)ucp->uc_link);
123		abort();
124	}
125}
126