1/*
2 * Copyright (c) 2003 Marcel Moolenaar
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/types.h>
31#include <sys/ucontext.h>
32#include <signal.h>
33#include <stdlib.h>
34#include <strings.h>
35
36typedef void (*handler_t)(uint64_t, uint64_t, uint64_t);
37
38/* Prototypes */
39static void sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args);
40
41__weak_reference(__signalcontext, signalcontext);
42
43int
44__signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
45{
46	uint64_t *args;
47	siginfo_t *sig_si;
48	ucontext_t *sig_uc;
49	uint64_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 signal frame and copy the arguments of signal handler
57	 * 'func' onto the stack and do the funky stack alignment.
58	 * This means that we need an 8-byte-odd alignment since the ABI expects
59	 * the return address to be pushed, thus breaking the 16 byte alignment.
60	 */
61	sp = (ucp->uc_mcontext.mc_rsp - 128 - sizeof(ucontext_t)) & ~15UL;
62	sig_uc = (ucontext_t *)sp;
63	bcopy(ucp, sig_uc, sizeof(*sig_uc));
64	sp = (sp - sizeof(siginfo_t)) & ~15UL;
65	sig_si = (siginfo_t *)sp;
66	bzero(sig_si, sizeof(*sig_si));
67	sig_si->si_signo = sig;
68	sp -= 3 * sizeof(uint64_t);
69	args = (uint64_t *)sp;
70	args[0] = sig;
71	args[1] = (intptr_t)sig_si;
72	args[2] = (intptr_t)sig_uc;
73	sp -= 16;
74
75	/*
76	 * Setup the ucontext of the signal handler.
77	 */
78	bzero(&ucp->uc_mcontext, sizeof(ucp->uc_mcontext));
79	ucp->uc_mcontext.mc_fpformat = _MC_FPFMT_NODEV;
80	ucp->uc_mcontext.mc_ownedfp = _MC_FPOWNED_NONE;
81	ucp->uc_link = sig_uc;
82	sigdelset(&ucp->uc_sigmask, sig);
83
84	ucp->uc_mcontext.mc_len = sizeof(mcontext_t);
85	ucp->uc_mcontext.mc_rdi = (register_t)ucp;
86	ucp->uc_mcontext.mc_rsi = (register_t)func;
87	ucp->uc_mcontext.mc_rdx = (register_t)args;
88	ucp->uc_mcontext.mc_rbp = (register_t)sp;
89	ucp->uc_mcontext.mc_rbx = (register_t)sp;
90	ucp->uc_mcontext.mc_rsp = (register_t)sp;
91	ucp->uc_mcontext.mc_rip = (register_t)sigctx_wrapper;
92	return (0);
93}
94
95static void
96sigctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args)
97{
98
99	(*func)(args[0], args[1], args[2]);
100	if (ucp->uc_link == NULL)
101		exit(0);
102	setcontext((const ucontext_t *)ucp->uc_link);
103	/* should never get here */
104	abort();
105	/* NOTREACHED */
106}
107