h_segv.c revision 1.14 
1/*	$NetBSD: h_segv.c,v 1.14 2019/04/25 19:37:09 kamil Exp $	*/
2
3/*-
4 * Copyright (c) 2017 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Christos Zoulas.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31#include <sys/cdefs.h>
32__RCSID("$NetBSD: h_segv.c,v 1.14 2019/04/25 19:37:09 kamil Exp $");
33
34#define	__TEST_FENV
35
36#include <sys/types.h>
37#include <sys/mman.h>
38#include <sys/ptrace.h>
39
40#include <err.h>
41#include <fenv.h>
42#if (__arm__ && !__SOFTFP__) || __aarch64__
43#include <ieeefp.h> /* only need for ARM Cortex/Neon hack */
44#endif
45#include <signal.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <string.h>
49#include <unistd.h>
50
51static int flags;
52#define F_RECURSE 	1
53#define F_HANDLE	2
54#define F_MASK		4
55#define F_IGNORE	8
56#define	F_CHECK		16
57
58static struct {
59	const char *n;
60	int v;
61} nv[] = {
62	{ "recurse",	F_RECURSE },
63	{ "handle",	F_HANDLE },
64	{ "mask",	F_MASK },
65	{ "ignore",	F_IGNORE },
66	{ "check",	F_CHECK }
67};
68
69static int sig;
70static struct {
71	const char *n;
72	int v;
73} sn[] = {
74	{ "segv",	SIGSEGV },
75	{ "trap",	SIGTRAP },
76	{ "ill",	SIGILL },
77	{ "fpe",	SIGFPE },
78	{ "bus",	SIGBUS }
79};
80
81static void
82trigger_segv(void)
83{
84	volatile int *p = (int *)(intptr_t)atoi("0");
85
86	*p = 1;
87}
88
89static void
90trigger_trap(void)
91{
92
93#ifdef PTRACE_BREAKPOINT_ASM
94	PTRACE_BREAKPOINT_ASM;
95#else
96	/* port me */
97#endif
98}
99
100static void
101trigger_ill(void)
102{
103
104#ifdef PTRACE_ILLEGAL_ASM
105	PTRACE_ILLEGAL_ASM;
106#else
107	/* port me */
108#endif
109}
110
111static void
112check_fpe(void)
113{
114#if (__arm__ && !__SOFTFP__) || __aarch64__
115	/*
116	 * Some NEON fpus do not trap on IEEE 754 FP exceptions.
117	 * Skip these tests if running on them and compiled for
118	 * hard float.
119	 */
120	if (0 == fpsetmask(fpsetmask(FP_X_INV))) {
121		printf("FPU does not implement traps on FP exceptions\n");
122		exit(EXIT_FAILURE);
123	}
124#endif
125	exit(EXIT_SUCCESS);
126}
127
128static void
129trigger_fpe(void)
130{
131	volatile double a = getpid();
132	volatile double b = strtol("0", NULL, 0);
133
134#ifdef __HAVE_FENV
135	feenableexcept(FE_ALL_EXCEPT);
136#endif
137
138	usleep((int)(a/b));
139}
140
141static void
142trigger_bus(void)
143{
144	FILE *fp;
145	char *p;
146
147	/* Open an empty file for writing. */
148	fp = tmpfile();
149	if (fp == NULL)
150		err(EXIT_FAILURE, "tmpfile");
151
152	/*
153	 * Map an empty file with mmap(2) to a pointer.
154	 *
155	 * PROT_READ handles read-modify-write sequences emitted for
156	 * certain combinations of CPUs and compilers (e.g. Alpha AXP).
157	 */
158	p = mmap(0, 1, PROT_READ|PROT_WRITE, MAP_PRIVATE, fileno(fp), 0);
159	if (p == MAP_FAILED)
160		err(EXIT_FAILURE, "mmap");
161
162	/* Invalid memory access causes CPU trap, translated to SIGBUS */
163	*p = 'a';
164}
165
166static void
167trigger(void)
168{
169
170	switch (sig) {
171	case SIGSEGV:
172		trigger_segv();
173		break;
174	case SIGTRAP:
175		trigger_trap();
176		break;
177	case SIGILL:
178		trigger_ill();
179		break;
180	case SIGFPE:
181		trigger_fpe();
182		break;
183	case SIGBUS:
184		trigger_bus();
185		break;
186	default:
187		break;
188	}
189}
190
191static void
192foo(int s)
193{
194	char buf[64];
195	int i = snprintf(buf, sizeof(buf), "got %d\n", s);
196	write(2, buf, i);
197
198	if (flags & F_RECURSE)
199		trigger();
200
201	exit(EXIT_SUCCESS);
202}
203
204static __dead void
205usage(void)
206{
207	const char *pname = getprogname();
208
209	fprintf(stderr, "Usage: %s segv|trap|ill|fpe|bus "
210	                "[recurse|mask|handle|ignore|check] ...\n", pname);
211
212	exit(EXIT_FAILURE);
213}
214
215int
216main(int argc, char *argv[])
217{
218
219	if (argc == 1)
220	    usage();
221
222	for (int i = 1; i < argc; i++) {
223		size_t j;
224		for (j = 0; j < __arraycount(nv); j++) {
225			if (strcmp(nv[j].n, argv[i]) == 0) {
226				flags |= nv[j].v;
227				goto consumed;
228			}
229		}
230		for (j = 0; j < __arraycount(sn); j++) {
231			if (strcmp(sn[j].n, argv[i]) == 0) {
232				sig = sn[j].v;
233				goto consumed;
234			}
235		}
236
237		usage();
238
239	consumed:
240		continue;
241	}
242
243	if (flags == 0 || sig == 0)
244		usage();
245
246	if (flags & F_CHECK && sig != SIGFPE) {
247		fprintf(stderr, "can only check for fpe support\n");
248		return 1;
249	}
250	if (flags & F_CHECK)
251		check_fpe();
252
253	if (flags & F_HANDLE) {
254		struct sigaction sa;
255
256		sa.sa_flags = SA_RESTART;
257		sa.sa_handler = foo;
258		sigemptyset(&sa.sa_mask);
259		if (sigaction(sig, &sa, NULL) == -1)
260			err(EXIT_FAILURE, "sigaction");
261	}
262
263	if (flags & F_MASK) {
264		sigset_t set;
265
266		sigemptyset(&set);
267		sigaddset(&set, sig);
268		if (sigprocmask(SIG_BLOCK, &set, NULL) == -1)
269			err(EXIT_FAILURE, "sigprocmask");
270	}
271
272	if (flags & F_IGNORE) {
273		struct sigaction sa;
274
275		memset(&sa, 0, sizeof(sa));
276		sa.sa_handler = SIG_IGN;
277		sigemptyset(&sa.sa_mask);
278		if (sigaction(sig, &sa, NULL) == -1)
279			err(EXIT_FAILURE, "sigaction");
280	}
281
282	trigger();
283
284	return EXIT_SUCCESS;
285}
286