signalcontext.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2002 Jonathan Mini <mini@freebsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30__FBSDID("$FreeBSD: stable/11/lib/libc/i386/gen/signalcontext.c 330897 2018-03-14 03:19:51Z eadler $");
31
32#include <sys/param.h>
33#include <sys/ucontext.h>
34#include <machine/psl.h>
35#include <machine/sigframe.h>
36#include <signal.h>
37#include <strings.h>
38
39__weak_reference(__signalcontext, signalcontext);
40
41extern void _ctx_start(ucontext_t *, int argc, ...);
42
43int
44__signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
45{
46	register_t *p;
47	struct sigframe *sfp;
48
49	/*-
50	 * Set up stack.
51	 * (n = sizeof(int))
52	 * 2n+sizeof(struct sigframe)	ucp
53	 * 2n				struct sigframe
54	 * 1n				&func
55	 * 0n				&_ctx_start
56	 */
57	p = (register_t *)(void *)(intptr_t)ucp->uc_mcontext.mc_esp;
58	*--p = (register_t)(intptr_t)ucp;
59	p = (register_t *)((u_register_t)p & ~0xF);  /* Align to 16 bytes. */
60	p = (register_t *)((u_register_t)p - sizeof(struct sigframe));
61	sfp = (struct sigframe *)p;
62	bzero(sfp, sizeof(struct sigframe));
63	sfp->sf_signum = sig;
64	sfp->sf_siginfo = (register_t)(intptr_t)&sfp->sf_si;
65	sfp->sf_ucontext = (register_t)(intptr_t)&sfp->sf_uc;
66	sfp->sf_ahu.sf_action = (__siginfohandler_t *)func;
67	bcopy(ucp, &sfp->sf_uc, sizeof(ucontext_t));
68	sfp->sf_si.si_signo = sig;
69	*--p = (register_t)(intptr_t)func;
70
71	/*
72	 * Set up ucontext_t.
73	 */
74	ucp->uc_mcontext.mc_esi = ucp->uc_mcontext.mc_esp - sizeof(int);
75	ucp->uc_mcontext.mc_esp = (register_t)(intptr_t)p;
76	ucp->uc_mcontext.mc_eip = (register_t)(intptr_t)_ctx_start;
77	ucp->uc_mcontext.mc_eflags &= ~PSL_T;
78	ucp->uc_link = &sfp->sf_uc;
79	sigdelset(&ucp->uc_sigmask, sig);
80	return (0);
81}
82