1 /* libunwind - a platform-independent unwind library
2 Copyright (C) 2004 Hewlett-Packard Co
3 Contributed by David Mosberger-Tang <davidm@hpl.hp.com>
4
5 Permission is hereby granted, free of charge, to any person obtaining
6 a copy of this software and associated documentation files (the
7 "Software"), to deal in the Software without restriction, including
8 without limitation the rights to use, copy, modify, merge, publish,
9 distribute, sublicense, and/or sell copies of the Software, and to
10 permit persons to whom the Software is furnished to do so, subject to
11 the following conditions:
12
13 The above copyright notice and this permission notice shall be
14 included in all copies or substantial portions of the Software.
15
16 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
23
24 /* Check whether basic unwinding truly is async-signal safe. */
25
26 #ifdef HAVE_CONFIG_H
27 #include "config.h"
28 #endif
29
30 #include "compiler.h"
31
32 #include <signal.h>
33 #include <stdio.h>
34 #include <stdlib.h>
35 #include <string.h>
36 #include <unistd.h>
37
38 #include <sys/time.h>
39
40 #define UNW_LOCAL_ONLY
41 #include <libunwind.h>
42
43 static const int nerrors_max = 100;
44
45 struct itimerval interval =
46 {
47 .it_interval = { .tv_sec = 0, .tv_usec = 0 },
48 .it_value = { .tv_sec = 0, .tv_usec = 1000 }
49 };
50
51 int verbose;
52 int nerrors;
53 int sigcount;
54
55 #ifndef CONFIG_BLOCK_SIGNALS
56 /* When libunwind is configured with --enable-block-signals=no, the caller
57 is responsible for preventing recursion via signal handlers.
58 We use a simple global here. In a multithreaded program, one would use
59 a thread-local variable. */
60 int recurcount;
61 #endif
62
63 #define panic(args...) \
64 { ++nerrors; fprintf (stderr, args); return; }
65
66 static void
do_backtrace(int may_print,int get_proc_name)67 do_backtrace (int may_print, int get_proc_name)
68 {
69 char buf[512], name[256];
70 unw_cursor_t cursor;
71 unw_word_t ip, sp, off;
72 unw_context_t uc;
73 int ret;
74 int depth = 0;
75
76 #ifndef CONFIG_BLOCK_SIGNALS
77 if (recurcount > 0)
78 return;
79 recurcount += 1;
80 #endif
81
82 unw_getcontext (&uc);
83 if (unw_init_local (&cursor, &uc) < 0)
84 panic ("unw_init_local failed!\n");
85
86 do
87 {
88 unw_get_reg (&cursor, UNW_REG_IP, &ip);
89 unw_get_reg (&cursor, UNW_REG_SP, &sp);
90
91 buf[0] = '\0';
92 if (get_proc_name || (may_print && verbose))
93 {
94 ret = unw_get_proc_name (&cursor, name, sizeof (name), &off);
95 if (ret == 0 && (may_print && verbose))
96 {
97 if (off)
98 snprintf (buf, sizeof (buf), "<%s+0x%lx>", name, (long) off);
99 else
100 {
101 size_t len = strlen (name);
102 buf[0] = '<';
103 memcpy (buf + 1, name, len);
104 buf[len + 1] = '>';
105 buf[len + 2] = '\0';
106 }
107 }
108 }
109
110 if (may_print && verbose)
111 printf ("%016lx %-32s (sp=%016lx)\n", (long) ip, buf, (long) sp);
112
113 ret = unw_step (&cursor);
114 if (ret < 0)
115 {
116 unw_get_reg (&cursor, UNW_REG_IP, &ip);
117 panic ("FAILURE: unw_step() returned %d for ip=%lx\n",
118 ret, (long) ip);
119 }
120 if (depth++ > 100)
121 {
122 panic ("FAILURE: unw_step() looping over %d iterations\n", depth);
123 break;
124 }
125 }
126 while (ret > 0);
127
128 #ifndef CONFIG_BLOCK_SIGNALS
129 recurcount -= 1;
130 #endif
131 }
132
133 void
sighandler(int signal)134 sighandler (int signal)
135 {
136 if (verbose)
137 printf ("sighandler(signal=%d, count=%d)\n", signal, sigcount);
138
139 do_backtrace (1, 1);
140
141 ++sigcount;
142
143 if (sigcount == 100)
144 unw_set_caching_policy (unw_local_addr_space, UNW_CACHE_GLOBAL);
145 else if (sigcount == 200)
146 unw_set_caching_policy (unw_local_addr_space, UNW_CACHE_PER_THREAD);
147 else if (sigcount == 300 || nerrors > nerrors_max)
148 {
149 if (nerrors > nerrors_max)
150 panic ("Too many errors (%d)\n", nerrors);
151 if (nerrors)
152 {
153 fprintf (stderr, "FAILURE: detected %d errors\n", nerrors);
154 exit (-1);
155 }
156 if (verbose)
157 printf ("SUCCESS.\n");
158 exit (0);
159 }
160 setitimer (ITIMER_VIRTUAL, &interval, NULL);
161 }
162
163 int
main(int argc,char ** argv UNUSED)164 main (int argc, char **argv UNUSED)
165 {
166 struct sigaction act;
167 long i = 0;
168
169 if (argc > 1)
170 verbose = 1;
171
172 unw_set_caching_policy (unw_local_addr_space, UNW_CACHE_NONE);
173
174 memset (&act, 0, sizeof (act));
175 act.sa_handler = sighandler;
176 act.sa_flags = SA_SIGINFO;
177 sigaction (SIGVTALRM, &act, NULL);
178
179 setitimer (ITIMER_VIRTUAL, &interval, NULL);
180
181 while (1)
182 {
183 if (0 && verbose)
184 printf ("%s: starting backtrace\n", __FUNCTION__);
185 do_backtrace (0, (i++ % 100) == 0);
186 if (nerrors > nerrors_max)
187 {
188 fprintf (stderr, "Too many errors (%d)\n", nerrors);
189 exit (-1);
190 }
191 }
192 return (0);
193 }
194