1/*
2 * Copyright (c) 2004 Marcel Moolenaar, Peter Grehan
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD$");
29
30#include <sys/param.h>
31#include <sys/ucontext.h>
32#include <signal.h>
33#include <stdlib.h>
34#include <strings.h>
35
36typedef void (*handler_t)(uint32_t, uint32_t, uint32_t);
37
38/* Prototypes */
39static void ctx_wrapper(ucontext_t *ucp, handler_t func, uint32_t sig,
40			uint32_t sig_si, uint32_t sig_uc);
41
42__weak_reference(__signalcontext, signalcontext);
43
44int
45__signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
46{
47	siginfo_t *sig_si;
48	ucontext_t *sig_uc;
49	uintptr_t sp;
50
51	/* Bail out if we don't have a valid ucontext pointer. */
52	if (ucp == NULL)
53		abort();
54
55	/*
56	 * Build a 16-byte-aligned signal frame
57	 */
58	sp = (ucp->uc_mcontext.mc_gpr[1] - sizeof(ucontext_t)) & ~15UL;
59	sig_uc = (ucontext_t *)sp;
60	bcopy(ucp, sig_uc, sizeof(*sig_uc));
61	sp = (sp - sizeof(siginfo_t)) & ~15UL;
62	sig_si = (siginfo_t *)sp;
63	bzero(sig_si, sizeof(*sig_si));
64	sig_si->si_signo = sig;
65
66	/*
67	 * Subtract 48 bytes from stack to allow for frameptr
68	 */
69	sp -= 6*sizeof(uint64_t);
70	sp &= ~15UL;
71
72	/*
73	 * Setup the ucontext of the signal handler.
74	 */
75	bzero(&ucp->uc_mcontext, sizeof(ucp->uc_mcontext));
76	ucp->uc_link = sig_uc;
77	sigdelset(&ucp->uc_sigmask, sig);
78
79	ucp->uc_mcontext.mc_vers = _MC_VERSION;
80	ucp->uc_mcontext.mc_len = sizeof(struct __mcontext);
81	ucp->uc_mcontext.mc_srr0 = (uint64_t) ctx_wrapper;
82	ucp->uc_mcontext.mc_gpr[1] = (uint64_t) sp;
83	ucp->uc_mcontext.mc_gpr[3] = (uint64_t) func;
84	ucp->uc_mcontext.mc_gpr[4] = (uint64_t) sig;
85	ucp->uc_mcontext.mc_gpr[5] = (uint64_t) sig_si;
86	ucp->uc_mcontext.mc_gpr[6] = (uint64_t) sig_uc;
87
88	return (0);
89}
90
91static void
92ctx_wrapper(ucontext_t *ucp, handler_t func, uint32_t sig, uint32_t sig_si,
93	    uint32_t sig_uc)
94{
95
96	(*func)(sig, sig_si, sig_uc);
97	if (ucp->uc_link == NULL)
98		exit(0);
99	setcontext((const ucontext_t *)ucp->uc_link);
100	/* should never get here */
101	abort();
102	/* NOTREACHED */
103}
104