signalcontext.c revision 116775 
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: head/lib/libc/ia64/gen/signalcontext.c 116775 2003-06-24 05:06:42Z marcel $");
29
30#include <sys/types.h>
31#include <sys/ucontext.h>
32#include <machine/fpu.h>
33#include <signal.h>
34#include <stdio.h>
35#include <strings.h>
36
37struct fdesc {
38	uint64_t ip;
39	uint64_t gp;
40};
41
42typedef void (*handler_t)(uint64_t, uint64_t, uint64_t);
43
44static __inline uint64_t *
45spill(uint64_t *bsp, uint64_t arg)
46{
47	*bsp++ = arg;
48	if (((intptr_t)bsp & 0x1ff) == 0x1f8)
49		*bsp++ = 0;
50	return (bsp);
51}
52
53static void
54ctx_wrapper(ucontext_t *ucp, handler_t func, uint64_t *args)
55{
56
57	(*func)(args[0], args[1], args[2]);
58	if (ucp->uc_link == NULL)
59		exit(0);
60	setcontext((const ucontext_t *)ucp->uc_link);
61	/* should never get here */
62	abort();
63	/* NOTREACHED */
64}
65
66__weak_reference(__signalcontext, signalcontext);
67
68int
69__signalcontext(ucontext_t *ucp, int sig, __sighandler_t *func)
70{
71	uint64_t *args, *bsp;
72	siginfo_t *sig_si;
73	ucontext_t *sig_uc;
74	uint64_t sp;
75
76	/* Bail out if we don't have a valid ucontext pointer. */
77	if (ucp == NULL)
78		abort();
79
80	/*
81	 * Build a signal frame and copy the arguments of signal handler
82	 * 'func' onto the (memory) stack. We only need 3 arguments, but
83	 * we create room for 4 so that we are 16-byte aligned.
84	 */
85	sp = (ucp->uc_mcontext.mc_special.sp - sizeof(ucontext_t)) & ~15UL;
86	sig_uc = (ucontext_t*)sp;
87	bcopy(ucp, sig_uc, sizeof(*sig_uc));
88	sp = (sp - sizeof(siginfo_t)) & ~15UL;
89	sig_si = (siginfo_t*)sp;
90	bzero(sig_si, sizeof(*sig_si));
91	sig_si->si_signo = sig;
92	sp -= 4 * sizeof(uint64_t);
93	args = (uint64_t*)sp;
94	args[0] = sig;
95	args[1] = (intptr_t)sig_si;
96	args[2] = (intptr_t)sig_uc;
97
98	/*
99	 * Push (spill) the arguments of the context wrapper onto the register
100	 * stack. They get loaded by the RSE on a context switch.
101	 */
102	bsp = (uint64_t*)ucp->uc_mcontext.mc_special.bspstore;
103	bsp = spill(bsp, (intptr_t)ucp);
104	bsp = spill(bsp, (intptr_t)func);
105	bsp = spill(bsp, (intptr_t)args);
106
107	/*
108	 * Setup the ucontext of the signal handler.
109	 */
110	memset(&ucp->uc_mcontext, 0, sizeof(ucp->uc_mcontext));
111	ucp->uc_link = sig_uc;
112	sigdelset(&ucp->uc_sigmask, sig);
113	ucp->uc_mcontext.mc_special.sp = (intptr_t)args - 16;
114	ucp->uc_mcontext.mc_special.bspstore = (intptr_t)bsp;
115	ucp->uc_mcontext.mc_special.pfs = (3 << 7) | 3;
116	ucp->uc_mcontext.mc_special.rsc = 0xf;
117	ucp->uc_mcontext.mc_special.rp = ((struct fdesc*)ctx_wrapper)->ip;
118	ucp->uc_mcontext.mc_special.gp = ((struct fdesc*)ctx_wrapper)->gp;
119	ucp->uc_mcontext.mc_special.fpsr = IA64_FPSR_DEFAULT;
120	return (0);
121}
122