1 /* libunwind - a platform-independent unwind library 2 Copyright (C) 2004 Hewlett-Packard Co 3 Contributed by David Mosberger-Tang <davidm (at) 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 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 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 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
