mono/mini/mini-posix.c

   1 /**
   2  * \file
   3  * POSIX signal handling support for Mono.
   4  *
   5  * Authors:
   6  *   Mono Team (mono-list@lists.ximian.com)
   7  *
   8  * Copyright 2001-2003 Ximian, Inc.
   9  * Copyright 2003-2008 Ximian, Inc.
  10  * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
  11  *
  12  * See LICENSE for licensing information.
  13  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  14  */
  15 #include <config.h>
  16 #include <signal.h>
  17 #ifdef HAVE_ALLOCA_H
  18 #include <alloca.h>
  19 #endif
  20 #ifdef HAVE_UNISTD_H
  21 #include <unistd.h>
  22 #endif
  23 #ifdef HAVE_EXECINFO_H
  24 #include <execinfo.h>
  25 #endif
  26 #include <math.h>
  27 #ifdef HAVE_SYS_TIME_H
  28 #include <sys/time.h>
  29 #endif
  30 #ifdef HAVE_SYS_SYSCALL_H
  31 #include <sys/syscall.h>
  32 #endif
  33 #ifdef HAVE_SYS_PRCTL_H
  34 #include <sys/prctl.h>
  35 #endif
  36 #ifdef HAVE_SYS_WAIT_H
  37 #include <sys/wait.h>
  38 #endif
  39 #include <errno.h>
  40 #include <sched.h>
  41
  42 #include <mono/metadata/assembly.h>
  43 #include <mono/metadata/loader.h>
  44 #include <mono/metadata/tabledefs.h>
  45 #include <mono/metadata/class.h>
  46 #include <mono/metadata/object.h>
  47 #include <mono/metadata/tokentype.h>
  48 #include <mono/metadata/tabledefs.h>
  49 #include <mono/metadata/threads.h>
  50 #include <mono/metadata/appdomain.h>
  51 #include <mono/metadata/debug-helpers.h>
  52 #include <mono/metadata/profiler-private.h>
  53 #include <mono/metadata/mono-config.h>
  54 #include <mono/metadata/environment.h>
  55 #include <mono/metadata/mono-debug.h>
  56 #include <mono/metadata/gc-internals.h>
  57 #include <mono/metadata/threads-types.h>
  58 #include <mono/metadata/verify.h>
  59 #include <mono/metadata/verify-internals.h>
  60 #include <mono/metadata/mempool-internals.h>
  61 #include <mono/metadata/attach.h>
  62 #include <mono/utils/mono-math.h>
  63 #include <mono/utils/mono-errno.h>
  64 #include <mono/utils/mono-compiler.h>
  65 #include <mono/utils/mono-counters.h>
  66 #include <mono/utils/mono-logger-internals.h>
  67 #include <mono/utils/mono-mmap.h>
  68 #include <mono/utils/dtrace.h>
  69 #include <mono/utils/mono-signal-handler.h>
  70 #include <mono/utils/mono-threads.h>
  71 #include <mono/utils/os-event.h>
  72 #include <mono/utils/mono-state.h>
  73 #include <mono/mini/debugger-state-machine.h>
  74
  75 #include "mini.h"
  76 #include <string.h>
  77 #include <ctype.h>
  78 #include "trace.h"
  79 #include "version.h"
  80 #include "debugger-agent.h"
  81 #include "mini-runtime.h"
  82 #include "jit-icalls.h"
  83
  84 #ifdef HOST_DARWIN
  85 #include <mach/mach.h>
  86 #include <mach/mach_time.h>
  87 #include <mach/clock.h>
  88 #include <mono/utils/mono-merp.h>
  89 #endif
  90
  91 #ifndef HOST_WIN32
  92 #include <mono/utils/mono-threads-debug.h>
  93 #endif
  94
  95 #include <fcntl.h>
  96 #ifndef HOST_WIN32
  97 #include <dlfcn.h>
  98 #endif
  99 #if HAVE_SYS_STAT_H
 100 #include <sys/stat.h>
 101 #endif
 102
 103 #if defined(HOST_WATCHOS)
 104
 105 void
 106 mono_runtime_setup_stat_profiler (void)
 107 {
 108         printf("WARNING: mono_runtime_setup_stat_profiler() called!\n");
 109 }
 110
 111
 112 void
 113 mono_runtime_shutdown_stat_profiler (void)
 114 {
 115 }
 116
 117
 118 gboolean
 119 MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
 120 {
 121         return FALSE;
 122 }
 123
 124 #ifndef HOST_DARWIN
 125 void
 126 mono_runtime_install_handlers (void)
 127 {
 128 }
 129 #endif
 130
 131 void
 132 mono_runtime_posix_install_handlers(void)
 133 {
 134         /* we still need to ignore SIGPIPE */
 135         signal (SIGPIPE, SIG_IGN);
 136 }
 137
 138 void
 139 mono_runtime_shutdown_handlers (void)
 140 {
 141 }
 142
 143 void
 144 mono_runtime_cleanup_handlers (void)
 145 {
 146 }
 147
 148 #else
 149
 150 static GHashTable *mono_saved_signal_handlers = NULL;
 151
 152 static struct sigaction *
 153 get_saved_signal_handler (int signo, gboolean remove)
 154 {
 155         if (mono_saved_signal_handlers) {
 156                 /* The hash is only modified during startup, so no need for locking */
 157                 struct sigaction *handler = (struct sigaction*)g_hash_table_lookup (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
 158                 if (remove && handler)
 159                         g_hash_table_remove (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
 160                 return handler;
 161         }
 162         return NULL;
 163 }
 164
 165 static void
 166 save_old_signal_handler (int signo, struct sigaction *old_action)
 167 {
 168         struct sigaction *handler_to_save = (struct sigaction *)g_malloc (sizeof (struct sigaction));
 169
 170         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_CONFIG,
 171                                 "Saving old signal handler for signal %d.", signo);
 172
 173         if (! (old_action->sa_flags & SA_SIGINFO)) {
 174                 handler_to_save->sa_handler = old_action->sa_handler;
 175         } else {
 176 #ifdef MONO_ARCH_USE_SIGACTION
 177                 handler_to_save->sa_sigaction = old_action->sa_sigaction;
 178 #endif /* MONO_ARCH_USE_SIGACTION */
 179         }
 180         handler_to_save->sa_mask = old_action->sa_mask;
 181         handler_to_save->sa_flags = old_action->sa_flags;
 182
 183         if (!mono_saved_signal_handlers)
 184                 mono_saved_signal_handlers = g_hash_table_new_full (NULL, NULL, NULL, g_free);
 185         g_hash_table_insert (mono_saved_signal_handlers, GINT_TO_POINTER (signo), handler_to_save);
 186 }
 187
 188 static void
 189 free_saved_signal_handlers (void)
 190 {
 191         g_hash_table_destroy (mono_saved_signal_handlers);
 192         mono_saved_signal_handlers = NULL;
 193 }
 194
 195 /*
 196  * mono_chain_signal:
 197  *
 198  *   Call the original signal handler for the signal given by the arguments, which
 199  * should be the same as for a signal handler. Returns TRUE if the original handler
 200  * was called, false otherwise.
 201  */
 202 gboolean
 203 MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
 204 {
 205         int signal = MONO_SIG_HANDLER_GET_SIGNO ();
 206         struct sigaction *saved_handler = (struct sigaction *)get_saved_signal_handler (signal, FALSE);
 207
 208         if (saved_handler && saved_handler->sa_handler) {
 209                 if (!(saved_handler->sa_flags & SA_SIGINFO)) {
 210                         saved_handler->sa_handler (signal);
 211                 } else {
 212 #ifdef MONO_ARCH_USE_SIGACTION
 213                         saved_handler->sa_sigaction (MONO_SIG_HANDLER_PARAMS);
 214 #endif /* MONO_ARCH_USE_SIGACTION */
 215                 }
 216                 return TRUE;
 217         }
 218         return FALSE;
 219 }
 220
 221 MONO_SIG_HANDLER_FUNC (static, sigabrt_signal_handler)
 222 {
 223         MonoJitInfo *ji = NULL;
 224         MonoContext mctx;
 225         MONO_SIG_HANDLER_INFO_TYPE *info = MONO_SIG_HANDLER_GET_INFO ();
 226         MONO_SIG_HANDLER_GET_CONTEXT;
 227
 228         if (mono_thread_internal_current ())
 229                 ji = mono_jit_info_table_find_internal (mono_domain_get (), mono_arch_ip_from_context (ctx), TRUE, TRUE);
 230         if (!ji) {
 231                 if (mono_chain_signal (MONO_SIG_HANDLER_PARAMS))
 232                         return;
 233                 mono_sigctx_to_monoctx (ctx, &mctx);
 234                 mono_handle_native_crash ("SIGABRT", &mctx, info);
 235         }
 236 }
 237
 238 MONO_SIG_HANDLER_FUNC (static, sigterm_signal_handler)
 239 {
 240 #ifndef DISABLE_CRASH_REPORTING
 241         MONO_SIG_HANDLER_GET_CONTEXT;
 242
 243         // Note: this is only run from the non-controlling thread
 244         MonoContext mctx;
 245         gchar *output = NULL;
 246         MonoStackHash hashes;
 247         mono_sigctx_to_monoctx (ctx, &mctx);
 248
 249         // Will return when the dumping is done, so this thread can continue
 250         // running. Returns FALSE on unrecoverable error.
 251         if (!mono_threads_summarize_execute (&mctx, &output, &hashes, FALSE, NULL, 0))
 252                 g_error ("Crash reporter dumper exited due to fatal error.");
 253 #endif
 254
 255         mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
 256 }
 257
 258 #if (defined (USE_POSIX_BACKEND) && defined (SIGRTMIN)) || defined (SIGPROF)
 259 #define HAVE_PROFILER_SIGNAL
 260 #endif
 261
 262 #ifdef HAVE_PROFILER_SIGNAL
 263
 264 static MonoNativeThreadId sampling_thread;
 265
 266 static gint32 profiler_signals_sent;
 267 static gint32 profiler_signals_received;
 268 static gint32 profiler_signals_accepted;
 269 static gint32 profiler_interrupt_signals_received;
 270
 271 MONO_SIG_HANDLER_FUNC (static, profiler_signal_handler)
 272 {
 273         int old_errno = errno;
 274
 275         MONO_SIG_HANDLER_GET_CONTEXT;
 276
 277         /* See the comment in mono_runtime_shutdown_stat_profiler (). */
 278         if (mono_native_thread_id_get () == sampling_thread) {
 279                 mono_atomic_inc_i32 (&profiler_interrupt_signals_received);
 280                 return;
 281         }
 282
 283         mono_atomic_inc_i32 (&profiler_signals_received);
 284
 285         // Did a non-attached or detaching thread get the signal?
 286         if (mono_thread_info_get_small_id () == -1 ||
 287             !mono_domain_get () ||
 288             !mono_tls_get_jit_tls ()) {
 289                 mono_set_errno (old_errno);
 290                 return;
 291         }
 292
 293         // See the comment in sampling_thread_func ().
 294         mono_atomic_store_i32 (&mono_thread_info_current ()->profiler_signal_ack, 1);
 295
 296         mono_atomic_inc_i32 (&profiler_signals_accepted);
 297
 298         int hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
 299
 300         mono_thread_info_set_is_async_context (TRUE);
 301
 302         MONO_PROFILER_RAISE (sample_hit, ((const mono_byte*)mono_arch_ip_from_context (ctx), ctx));
 303
 304         mono_thread_info_set_is_async_context (FALSE);
 305
 306         mono_hazard_pointer_restore_for_signal_handler (hp_save_index);
 307
 308         mono_set_errno (old_errno);
 309
 310         mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
 311 }
 312
 313 #endif
 314
 315 MONO_SIG_HANDLER_FUNC (static, sigquit_signal_handler)
 316 {
 317         gboolean res;
 318
 319         /* We use this signal to start the attach agent too */
 320         res = mono_attach_start ();
 321         if (res)
 322                 return;
 323
 324         mono_threads_request_thread_dump ();
 325
 326         mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
 327 }
 328
 329 MONO_SIG_HANDLER_FUNC (static, sigusr2_signal_handler)
 330 {
 331         gboolean enabled = mono_trace_is_enabled ();
 332
 333         mono_trace_enable (!enabled);
 334
 335         mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
 336 }
 337
 338 typedef void MONO_SIG_HANDLER_SIGNATURE ((*MonoSignalHandler));
 339
 340 static void
 341 add_signal_handler (int signo, MonoSignalHandler handler, int flags)
 342 {
 343         struct sigaction sa;
 344         struct sigaction previous_sa;
 345
 346 #ifdef MONO_ARCH_USE_SIGACTION
 347         sa.sa_sigaction = handler;
 348         sigemptyset (&sa.sa_mask);
 349         sa.sa_flags = SA_SIGINFO | flags;
 350 #ifdef MONO_ARCH_SIGSEGV_ON_ALTSTACK
 351
 352 /*Apple likes to deliver SIGBUS for *0 */
 353 #ifdef HOST_DARWIN
 354         if (signo == SIGSEGV || signo == SIGBUS) {
 355 #else
 356         if (signo == SIGSEGV) {
 357 #endif
 358                 sa.sa_flags |= SA_ONSTACK;
 359
 360                 /*
 361                  * libgc will crash when trying to do stack marking for threads which are on
 362                  * an altstack, so delay the suspend signal after the signal handler has
 363                  * executed.
 364                  */
 365                 if (mono_gc_get_suspend_signal () != -1)
 366                         sigaddset (&sa.sa_mask, mono_gc_get_suspend_signal ());
 367         }
 368 #endif
 369         if (signo == SIGSEGV) {
 370                 /*
 371                  * Delay abort signals while handling SIGSEGVs since they could go unnoticed.
 372                  */
 373                 sigset_t block_mask;
 374
 375                 sigemptyset (&block_mask);
 376         }
 377 #else
 378         sa.sa_handler = (void (*)(int))handler;
 379         sigemptyset (&sa.sa_mask);
 380         sa.sa_flags = flags;
 381 #endif
 382         g_assert (sigaction (signo, &sa, &previous_sa) != -1);
 383
 384         /* if there was already a handler in place for this signal, store it */
 385         if (! (previous_sa.sa_flags & SA_SIGINFO) &&
 386                         (SIG_DFL == previous_sa.sa_handler)) {
 387                 /* it there is no sa_sigaction function and the sa_handler is default, we can safely ignore this */
 388         } else {
 389                 if (mono_do_signal_chaining)
 390                         save_old_signal_handler (signo, &previous_sa);
 391         }
 392 }
 393
 394 static void
 395 remove_signal_handler (int signo)
 396 {
 397         struct sigaction sa;
 398         struct sigaction *saved_action = get_saved_signal_handler (signo, TRUE);
 399
 400         if (!saved_action) {
 401                 sa.sa_handler = SIG_DFL;
 402                 sigemptyset (&sa.sa_mask);
 403                 sa.sa_flags = 0;
 404
 405                 sigaction (signo, &sa, NULL);
 406         } else {
 407                 g_assert (sigaction (signo, saved_action, NULL) != -1);
 408         }
 409 }
 410
 411 void
 412 mini_register_sigterm_handler (void)
 413 {
 414 #ifndef DISABLE_CRASH_REPORTING
 415         static gboolean enabled;
 416
 417         if (!enabled) {
 418                 enabled = TRUE;
 419
 420                 /* always catch SIGTERM, conditionals inside of handler */
 421                 add_signal_handler (SIGTERM, sigterm_signal_handler, 0);
 422         }
 423 #endif
 424 }
 425
 426 void
 427 mono_runtime_posix_install_handlers (void)
 428 {
 429
 430         sigset_t signal_set;
 431         sigemptyset (&signal_set);
 432         if (mini_get_debug_options ()->handle_sigint) {
 433                 add_signal_handler (SIGINT, mono_sigint_signal_handler, SA_RESTART);
 434                 sigaddset (&signal_set, SIGINT);
 435         }
 436
 437         add_signal_handler (SIGFPE, mono_sigfpe_signal_handler, 0);
 438         sigaddset (&signal_set, SIGFPE);
 439         add_signal_handler (SIGQUIT, sigquit_signal_handler, SA_RESTART);
 440         sigaddset (&signal_set, SIGQUIT);
 441         add_signal_handler (SIGILL, mono_sigill_signal_handler, 0);
 442         sigaddset (&signal_set, SIGILL);
 443         add_signal_handler (SIGBUS, mono_sigsegv_signal_handler, 0);
 444         sigaddset (&signal_set, SIGBUS);
 445         if (mono_jit_trace_calls != NULL) {
 446                 add_signal_handler (SIGUSR2, sigusr2_signal_handler, SA_RESTART);
 447                 sigaddset (&signal_set, SIGUSR2);
 448         }
 449
 450         /* it seems to have become a common bug for some programs that run as parents
 451          * of many processes to block signal delivery for real time signals.
 452          * We try to detect and work around their breakage here.
 453          */
 454         if (mono_gc_get_suspend_signal () != -1)
 455                 sigaddset (&signal_set, mono_gc_get_suspend_signal ());
 456         if (mono_gc_get_restart_signal () != -1)
 457                 sigaddset (&signal_set, mono_gc_get_restart_signal ());
 458         sigaddset (&signal_set, SIGCHLD);
 459
 460         signal (SIGPIPE, SIG_IGN);
 461         sigaddset (&signal_set, SIGPIPE);
 462
 463         add_signal_handler (SIGABRT, sigabrt_signal_handler, 0);
 464         sigaddset (&signal_set, SIGABRT);
 465
 466         /* catch SIGSEGV */
 467         add_signal_handler (SIGSEGV, mono_sigsegv_signal_handler, 0);
 468         sigaddset (&signal_set, SIGSEGV);
 469
 470         sigprocmask (SIG_UNBLOCK, &signal_set, NULL);
 471 }
 472
 473 #ifndef HOST_DARWIN
 474 void
 475 mono_runtime_install_handlers (void)
 476 {
 477         mono_runtime_posix_install_handlers ();
 478 }
 479 #endif
 480
 481 void
 482 mono_runtime_cleanup_handlers (void)
 483 {
 484         if (mini_get_debug_options ()->handle_sigint)
 485                 remove_signal_handler (SIGINT);
 486
 487         remove_signal_handler (SIGFPE);
 488         remove_signal_handler (SIGQUIT);
 489         remove_signal_handler (SIGILL);
 490         remove_signal_handler (SIGBUS);
 491         if (mono_jit_trace_calls != NULL)
 492                 remove_signal_handler (SIGUSR2);
 493
 494         remove_signal_handler (SIGABRT);
 495
 496         remove_signal_handler (SIGSEGV);
 497
 498         free_saved_signal_handlers ();
 499 }
 500
 501 #ifdef HAVE_PROFILER_SIGNAL
 502
 503 static volatile gint32 sampling_thread_running;
 504
 505 #ifdef HOST_DARWIN
 506
 507 static clock_serv_t sampling_clock_service;
 508
 509 static void
 510 clock_init (MonoProfilerSampleMode mode)
 511 {
 512         kern_return_t ret;
 513
 514         do {
 515                 ret = host_get_clock_service (mach_host_self (), SYSTEM_CLOCK, &sampling_clock_service);
 516         } while (ret == KERN_ABORTED);
 517
 518         if (ret != KERN_SUCCESS)
 519                 g_error ("%s: host_get_clock_service () returned %d", __func__, ret);
 520 }
 521
 522 static void
 523 clock_cleanup (void)
 524 {
 525         kern_return_t ret;
 526
 527         do {
 528                 ret = mach_port_deallocate (mach_task_self (), sampling_clock_service);
 529         } while (ret == KERN_ABORTED);
 530
 531         if (ret != KERN_SUCCESS)
 532                 g_error ("%s: mach_port_deallocate () returned %d", __func__, ret);
 533 }
 534
 535 static guint64
 536 clock_get_time_ns (void)
 537 {
 538         kern_return_t ret;
 539         mach_timespec_t mach_ts;
 540
 541         do {
 542                 ret = clock_get_time (sampling_clock_service, &mach_ts);
 543         } while (ret == KERN_ABORTED);
 544
 545         if (ret != KERN_SUCCESS)
 546                 g_error ("%s: clock_get_time () returned %d", __func__, ret);
 547
 548         return ((guint64) mach_ts.tv_sec * 1000000000) + (guint64) mach_ts.tv_nsec;
 549 }
 550
 551 static void
 552 clock_sleep_ns_abs (guint64 ns_abs)
 553 {
 554         kern_return_t ret;
 555         mach_timespec_t then, remain_unused;
 556
 557         then.tv_sec = ns_abs / 1000000000;
 558         then.tv_nsec = ns_abs % 1000000000;
 559
 560         do {
 561                 ret = clock_sleep (sampling_clock_service, TIME_ABSOLUTE, then, &remain_unused);
 562
 563                 if (ret != KERN_SUCCESS && ret != KERN_ABORTED)
 564                         g_error ("%s: clock_sleep () returned %d", __func__, ret);
 565         } while (ret == KERN_ABORTED && mono_atomic_load_i32 (&sampling_thread_running));
 566 }
 567
 568 #else
 569
 570 static clockid_t sampling_posix_clock;
 571
 572 static void
 573 clock_init (MonoProfilerSampleMode mode)
 574 {
 575         switch (mode) {
 576         case MONO_PROFILER_SAMPLE_MODE_PROCESS: {
 577         /*
 578          * If we don't have clock_nanosleep (), measuring the process time
 579          * makes very little sense as we can only use nanosleep () to sleep on
 580          * real time.
 581          */
 582 #ifdef HAVE_CLOCK_NANOSLEEP
 583                 struct timespec ts = { 0 };
 584
 585                 /*
 586                  * Some systems (e.g. Windows Subsystem for Linux) declare the
 587                  * CLOCK_PROCESS_CPUTIME_ID clock but don't actually support it. For
 588                  * those systems, we fall back to CLOCK_MONOTONIC if we get EINVAL.
 589                  */
 590                 if (clock_nanosleep (CLOCK_PROCESS_CPUTIME_ID, TIMER_ABSTIME, &ts, NULL) != EINVAL) {
 591                         sampling_posix_clock = CLOCK_PROCESS_CPUTIME_ID;
 592                         break;
 593                 }
 594 #endif
 595
 596                 // fallthrough
 597         }
 598         case MONO_PROFILER_SAMPLE_MODE_REAL: sampling_posix_clock = CLOCK_MONOTONIC; break;
 599         default: g_assert_not_reached (); break;
 600         }
 601 }
 602
 603 static void
 604 clock_cleanup (void)
 605 {
 606 }
 607
 608 static guint64
 609 clock_get_time_ns (void)
 610 {
 611         struct timespec ts;
 612
 613         if (clock_gettime (sampling_posix_clock, &ts) == -1)
 614                 g_error ("%s: clock_gettime () returned -1, errno = %d", __func__, errno);
 615
 616         return ((guint64) ts.tv_sec * 1000000000) + (guint64) ts.tv_nsec;
 617 }
 618
 619 static void
 620 clock_sleep_ns_abs (guint64 ns_abs)
 621 {
 622 #ifdef HAVE_CLOCK_NANOSLEEP
 623         int ret;
 624         struct timespec then;
 625
 626         then.tv_sec = ns_abs / 1000000000;
 627         then.tv_nsec = ns_abs % 1000000000;
 628
 629         do {
 630                 ret = clock_nanosleep (sampling_posix_clock, TIMER_ABSTIME, &then, NULL);
 631
 632                 if (ret != 0 && ret != EINTR)
 633                         g_error ("%s: clock_nanosleep () returned %d", __func__, ret);
 634         } while (ret == EINTR && mono_atomic_load_i32 (&sampling_thread_running));
 635 #else
 636         int ret;
 637         gint64 diff;
 638         struct timespec req;
 639
 640         /*
 641          * What follows is a crude attempt at emulating clock_nanosleep () on OSs
 642          * which don't provide it (e.g. FreeBSD).
 643          *
 644          * The problem with nanosleep () is that if it is interrupted by a signal,
 645          * time will drift as a result of having to restart the call after the
 646          * signal handler has finished. For this reason, we avoid using the rem
 647          * argument of nanosleep (). Instead, before every nanosleep () call, we
 648          * check if enough time has passed to satisfy the sleep request. If yes, we
 649          * simply return. If not, we calculate the difference and do another sleep.
 650          *
 651          * This should reduce the amount of drift that happens because we account
 652          * for the time spent executing the signal handler, which nanosleep () is
 653          * not guaranteed to do for the rem argument.
 654          *
 655          * The downside to this approach is that it is slightly expensive: We have
 656          * to make an extra system call to retrieve the current time whenever we're
 657          * going to restart a nanosleep () call. This is unlikely to be a problem
 658          * in practice since the sampling thread won't be receiving many signals in
 659          * the first place (it's a tools thread, so no STW), and because typical
 660          * sleep periods for the thread are many orders of magnitude bigger than
 661          * the time it takes to actually perform that system call (just a few
 662          * nanoseconds).
 663          */
 664         do {
 665                 diff = (gint64) ns_abs - (gint64) clock_get_time_ns ();
 666
 667                 if (diff <= 0)
 668                         break;
 669
 670                 req.tv_sec = diff / 1000000000;
 671                 req.tv_nsec = diff % 1000000000;
 672
 673                 if ((ret = nanosleep (&req, NULL)) == -1 && errno != EINTR)
 674                         g_error ("%s: nanosleep () returned -1, errno = %d", __func__, errno);
 675         } while (ret == -1 && mono_atomic_load_i32 (&sampling_thread_running));
 676 #endif
 677 }
 678
 679 #endif
 680
 681 static int profiler_signal;
 682 static volatile gint32 sampling_thread_exiting;
 683 static MonoOSEvent sampling_thread_exited;
 684
 685 static gsize
 686 sampling_thread_func (gpointer unused)
 687 {
 688         MonoInternalThread *thread = mono_thread_internal_current ();
 689
 690         thread->flags |= MONO_THREAD_FLAG_DONT_MANAGE;
 691
 692         ERROR_DECL (error);
 693
 694         MonoString *name = mono_string_new_checked (mono_get_root_domain (), "Profiler Sampler", error);
 695         mono_error_assert_ok (error);
 696         mono_thread_set_name_internal (thread, name, FALSE, FALSE, error);
 697         mono_error_assert_ok (error);
 698
 699         mono_thread_info_set_flags (MONO_THREAD_INFO_FLAGS_NO_GC | MONO_THREAD_INFO_FLAGS_NO_SAMPLE);
 700
 701         int old_policy;
 702         struct sched_param old_sched;
 703         pthread_getschedparam (pthread_self (), &old_policy, &old_sched);
 704
 705         /*
 706          * Attempt to switch the thread to real time scheduling. This will not
 707          * necessarily work on all OSs; for example, most Linux systems will give
 708          * us EPERM here unless configured to allow this.
 709          *
 710          * TODO: This does not work on Mac (and maybe some other OSs). On Mac, we
 711          * have to use the Mach thread policy routines to switch to real-time
 712          * scheduling. This is quite tricky as we need to specify how often we'll
 713          * be doing work (easy), the normal processing time needed (also easy),
 714          * and the maximum amount of processing time needed (hard). This is
 715          * further complicated by the fact that if we misbehave and take too long
 716          * to do our work, the kernel may knock us back down to the normal thread
 717          * scheduling policy without telling us.
 718          */
 719         struct sched_param sched;
 720         memset (&sched, 0, sizeof (sched));
 721         sched.sched_priority = sched_get_priority_max (SCHED_FIFO);
 722         pthread_setschedparam (pthread_self (), SCHED_FIFO, &sched);
 723
 724         MonoProfilerSampleMode mode;
 725
 726 init:
 727         mono_profiler_get_sample_mode (NULL, &mode, NULL);
 728
 729         if (mode == MONO_PROFILER_SAMPLE_MODE_NONE) {
 730                 mono_profiler_sampling_thread_wait ();
 731
 732                 if (!mono_atomic_load_i32 (&sampling_thread_running))
 733                         goto done;
 734
 735                 goto init;
 736         }
 737
 738         clock_init (mode);
 739
 740         for (guint64 sleep = clock_get_time_ns (); mono_atomic_load_i32 (&sampling_thread_running); clock_sleep_ns_abs (sleep)) {
 741                 uint32_t freq;
 742                 MonoProfilerSampleMode new_mode;
 743
 744                 mono_profiler_get_sample_mode (NULL, &new_mode, &freq);
 745
 746                 if (new_mode != mode) {
 747                         clock_cleanup ();
 748                         goto init;
 749                 }
 750
 751                 sleep += 1000000000 / freq;
 752
 753                 FOREACH_THREAD_SAFE_EXCLUDE (info, MONO_THREAD_INFO_FLAGS_NO_SAMPLE) {
 754                         g_assert (mono_thread_info_get_tid (info) != sampling_thread);
 755
 756                         /*
 757                          * Require an ack for the last sampling signal sent to the thread
 758                          * so that we don't overflow the signal queue, leading to all sorts
 759                          * of problems (e.g. GC STW failing).
 760                          */
 761                         if (profiler_signal != SIGPROF && !mono_atomic_cas_i32 (&info->profiler_signal_ack, 0, 1))
 762                                 continue;
 763
 764                         mono_threads_pthread_kill (info, profiler_signal);
 765                         mono_atomic_inc_i32 (&profiler_signals_sent);
 766                 } FOREACH_THREAD_SAFE_END
 767         }
 768
 769         clock_cleanup ();
 770
 771 done:
 772         mono_atomic_store_i32 (&sampling_thread_exiting, 1);
 773
 774         pthread_setschedparam (pthread_self (), old_policy, &old_sched);
 775
 776         mono_thread_info_set_flags (MONO_THREAD_INFO_FLAGS_NONE);
 777
 778         mono_os_event_set (&sampling_thread_exited);
 779
 780         return 0;
 781 }
 782
 783 void
 784 mono_runtime_shutdown_stat_profiler (void)
 785 {
 786         mono_atomic_store_i32 (&sampling_thread_running, 0);
 787
 788         mono_profiler_sampling_thread_post ();
 789
 790 #ifndef HOST_DARWIN
 791         /*
 792          * There is a slight problem when we're using CLOCK_PROCESS_CPUTIME_ID: If
 793          * we're shutting down and there's largely no activity in the process other
 794          * than waiting for the sampler thread to shut down, it can take upwards of
 795          * 20 seconds (depending on a lot of factors) for us to shut down because
 796          * the sleep progresses very slowly as a result of the low CPU activity.
 797          *
 798          * We fix this by repeatedly sending the profiler signal to the sampler
 799          * thread in order to interrupt the sleep. clock_sleep_ns_abs () will check
 800          * sampling_thread_running upon an interrupt and return immediately if it's
 801          * zero. profiler_signal_handler () has a special case to ignore the signal
 802          * for the sampler thread.
 803          */
 804         MonoThreadInfo *info;
 805
 806         // Did it shut down already?
 807         if ((info = mono_thread_info_lookup (sampling_thread))) {
 808                 while (!mono_atomic_load_i32 (&sampling_thread_exiting)) {
 809                         mono_threads_pthread_kill (info, profiler_signal);
 810                         mono_thread_info_usleep (10 * 1000 /* 10ms */);
 811                 }
 812
 813                 // Make sure info can be freed.
 814                 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
 815         }
 816 #endif
 817
 818         mono_os_event_wait_one (&sampling_thread_exited, MONO_INFINITE_WAIT, FALSE);
 819         mono_os_event_destroy (&sampling_thread_exited);
 820
 821         /*
 822          * We can't safely remove the signal handler because we have no guarantee
 823          * that all pending signals have been delivered at this point. This should
 824          * not really be a problem anyway.
 825          */
 826         //remove_signal_handler (profiler_signal);
 827 }
 828
 829 void
 830 mono_runtime_setup_stat_profiler (void)
 831 {
 832         /*
 833          * Use a real-time signal when possible. This gives us roughly a 99% signal
 834          * delivery rate in all cases. On the other hand, using a regular signal
 835          * tends to result in awful delivery rates when the application is heavily
 836          * loaded.
 837          *
 838          * We avoid real-time signals on Android as they're super broken in certain
 839          * API levels (too small sigset_t, nonsensical SIGRTMIN/SIGRTMAX values,
 840          * etc).
 841          *
 842          * TODO: On Mac, we should explore using the Mach thread suspend/resume
 843          * functions and doing the stack walk from the sampling thread. This would
 844          * get us a 100% sampling rate. However, this may interfere with the GC's
 845          * STW logic. Could perhaps be solved by taking the suspend lock.
 846          */
 847 #if defined (USE_POSIX_BACKEND) && defined (SIGRTMIN) && !defined (HOST_ANDROID)
 848         /* Just take the first real-time signal we can get. */
 849         profiler_signal = mono_threads_suspend_search_alternative_signal ();
 850 #else
 851         profiler_signal = SIGPROF;
 852 #endif
 853
 854         add_signal_handler (profiler_signal, profiler_signal_handler, SA_RESTART);
 855
 856         mono_counters_register ("Sampling signals sent", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_sent);
 857         mono_counters_register ("Sampling signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_received);
 858         mono_counters_register ("Sampling signals accepted", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_accepted);
 859         mono_counters_register ("Shutdown signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_interrupt_signals_received);
 860
 861         mono_os_event_init (&sampling_thread_exited, FALSE);
 862
 863         mono_atomic_store_i32 (&sampling_thread_running, 1);
 864
 865         MonoError error;
 866         MonoInternalThread *thread = mono_thread_create_internal (mono_get_root_domain (), (gpointer)sampling_thread_func, NULL, MONO_THREAD_CREATE_FLAGS_NONE, &error);
 867         mono_error_assert_ok (&error);
 868
 869         sampling_thread = MONO_UINT_TO_NATIVE_THREAD_ID (thread->tid);
 870 }
 871
 872 #else
 873
 874 void
 875 mono_runtime_shutdown_stat_profiler (void)
 876 {
 877 }
 878
 879 void
 880 mono_runtime_setup_stat_profiler (void)
 881 {
 882 }
 883
 884 #endif
 885
 886 #endif /* defined(HOST_WATCHOS) */
 887
 888 #ifndef MONO_CROSS_COMPILE
 889 static void
 890 dump_memory_around_ip (MonoContext *mctx)
 891 {
 892         if (!mctx)
 893                 return;
 894
 895         g_async_safe_printf ("\n=================================================================\n");
 896         g_async_safe_printf ("\tBasic Fault Address Reporting\n");
 897         g_async_safe_printf ("=================================================================\n");
 898
 899         gpointer native_ip = MONO_CONTEXT_GET_IP (mctx);
 900         if (native_ip) {
 901                 g_async_safe_printf ("Memory around native instruction pointer (%p):", native_ip);
 902                 mono_dump_mem (((guint8 *) native_ip) - 0x10, 0x40);
 903         } else {
 904                 g_async_safe_printf ("instruction pointer is NULL, skip dumping");
 905         }
 906 }
 907
 908 static void
 909 assert_printer_callback (void)
 910 {
 911         mono_dump_native_crash_info ("SIGABRT", NULL, NULL);
 912 }
 913
 914 static void
 915 dump_native_stacktrace (const char *signal, MonoContext *mctx)
 916 {
 917         mono_memory_barrier ();
 918         static gint32 middle_of_crash = 0x0;
 919         gint32 double_faulted = mono_atomic_cas_i32 ((gint32 *)&middle_of_crash, 0x1, 0x0);
 920         mono_memory_write_barrier ();
 921
 922         if (!double_faulted) {
 923                 g_assertion_disable_global (assert_printer_callback);
 924         } else {
 925                 g_async_safe_printf ("\nAn error has occured in the native fault reporting. Some diagnostic information will be unavailable.\n");
 926
 927 #ifndef DISABLE_CRASH_REPORTING
 928                 // In case still enabled
 929                 mono_summarize_toggle_assertions (FALSE);
 930 #endif
 931         }
 932
 933 #ifdef HAVE_BACKTRACE_SYMBOLS
 934
 935         void *array [256];
 936         int size = backtrace (array, 256);
 937
 938         g_async_safe_printf ("\n=================================================================\n");
 939         g_async_safe_printf ("\tNative stacktrace:\n");
 940         g_async_safe_printf ("=================================================================\n");
 941         if (size == 0)
 942                 g_async_safe_printf ("\t (No frames) \n\n");
 943
 944         for (int i = 0; i < size; ++i) {
 945                 gpointer ip = array [i];
 946                 Dl_info info;
 947                 gboolean success = dladdr ((void*) ip, &info);
 948                 if (!success) {
 949                         g_async_safe_printf ("\t%p - Unknown\n", ip);
 950                 } else {
 951                         g_async_safe_printf ("\t%p - %s : %s\n", ip, info.dli_fname, info.dli_sname);
 952                 }
 953         }
 954
 955 #if !defined(HOST_WIN32) && defined(HAVE_SYS_SYSCALL_H) && (defined(SYS_fork) || HAVE_FORK)
 956         if (!mini_get_debug_options ()->no_gdb_backtrace) {
 957                 /* From g_spawn_command_line_sync () in eglib */
 958                 pid_t pid;
 959                 int status;
 960                 pid_t crashed_pid = getpid ();
 961                 gchar *output = NULL;
 962                 MonoStackHash hashes;
 963
 964 #ifndef DISABLE_CRASH_REPORTING
 965                 MonoStateMem merp_mem;
 966                 memset (&merp_mem, 0, sizeof (merp_mem));
 967
 968                 if (!double_faulted) {
 969                         gboolean leave = FALSE;
 970                         gboolean dump_for_merp = FALSE;
 971 #if defined(TARGET_OSX)
 972                         dump_for_merp = mono_merp_enabled ();
 973 #endif
 974
 975                         if (!dump_for_merp) {
 976 #ifdef DISABLE_STRUCTURED_CRASH
 977                                 leave = TRUE;
 978 #else
 979                                 mini_register_sigterm_handler ();
 980 #endif
 981                         }
 982
 983                         MonoContext *passed_ctx = NULL;
 984                         if (!leave && mctx) {
 985                                 passed_ctx = mctx;
 986                         }
 987
 988                         g_async_safe_printf ("\n=================================================================\n");
 989                         g_async_safe_printf ("\tTelemetry Dumper:\n");
 990                         g_async_safe_printf ("=================================================================\n");
 991
 992                         if (!leave) {
 993                                 mono_summarize_timeline_start ();
 994                                 mono_summarize_toggle_assertions (TRUE);
 995
 996                                 int mono_max_summary_len = 500000;
 997                                 int mono_state_tmp_file_tag = 1;
 998                                 mono_state_alloc_mem (&merp_mem, mono_state_tmp_file_tag, mono_max_summary_len * sizeof (gchar));
 999
1000                                 // Returns success, so leave if !success
1001                                 leave = !mono_threads_summarize (passed_ctx, &output, &hashes, FALSE, TRUE, (gchar *) merp_mem.mem, mono_max_summary_len);
1002                         }
1003
1004                         if (!leave) {
1005                                 // Wait for the other threads to clean up and exit their handlers
1006                                 // We can't lock / wait indefinitely, in case one of these threads got stuck somehow
1007                                 // while dumping.
1008                                 g_async_safe_printf ("\nWaiting for dumping threads to resume\n");
1009                                 sleep (1);
1010                         }
1011
1012                         // We want our crash, and don't have telemetry
1013                         // So we dump to disk
1014                         if (!leave && !dump_for_merp) {
1015                                 mono_summarize_timeline_phase_log (MonoSummaryCleanup);
1016                                 mono_crash_dump (output, &hashes);
1017                                 mono_summarize_timeline_phase_log (MonoSummaryDone);
1018                                 mono_summarize_toggle_assertions (FALSE);
1019                         }
1020                 }
1021 #endif // DISABLE_CRASH_REPORTING
1022
1023                 /*
1024                 * glibc fork acquires some locks, so if the crash happened inside malloc/free,
1025                 * it will deadlock. Call the syscall directly instead.
1026                 */
1027 #if defined(HOST_ANDROID)
1028                 /* SYS_fork is defined to be __NR_fork which is not defined in some ndk versions */
1029                 g_assert_not_reached ();
1030 #elif !defined(HOST_DARWIN) && defined(SYS_fork)
1031                 pid = (pid_t) syscall (SYS_fork);
1032 #elif HAVE_FORK
1033                 pid = (pid_t) fork ();
1034 #else
1035                 g_assert_not_reached ();
1036 #endif
1037
1038 #if defined (HAVE_PRCTL) && defined(PR_SET_PTRACER)
1039                 if (pid > 0) {
1040                         // Allow gdb to attach to the process even if ptrace_scope sysctl variable is set to
1041                         // a value other than 0 (the most permissive ptrace scope). Most modern Linux
1042                         // distributions set the scope to 1 which allows attaching only to direct children of
1043                         // the current process
1044                         prctl (PR_SET_PTRACER, pid, 0, 0, 0);
1045                 }
1046 #endif
1047
1048 #if defined(TARGET_OSX) && !defined(DISABLE_CRASH_REPORTING)
1049                 if (!double_faulted && mono_merp_enabled ()) {
1050                         if (pid == 0) {
1051                                 if (output) {
1052                                         gboolean merp_upload_success = mono_merp_invoke (crashed_pid, signal, output, &hashes);
1053
1054                                         if (!merp_upload_success) {
1055                                                 g_async_safe_printf("\nThe MERP upload step has failed.\n");
1056                                         } else {
1057                                                 // Remove
1058                                                 g_async_safe_printf("\nThe MERP upload step has succeeded.\n");
1059                                                 mono_summarize_timeline_phase_log (MonoSummaryDone);
1060                                         }
1061
1062                                         mono_summarize_toggle_assertions (FALSE);
1063                                 } else {
1064                                         g_async_safe_printf("\nMerp dump step not run, no dump created.\n");
1065                                 }
1066                         }
1067                 }
1068 #endif
1069
1070                 if (pid == 0) {
1071                         dup2 (STDERR_FILENO, STDOUT_FILENO);
1072
1073                         g_async_safe_printf ("\n=================================================================\n");
1074                         g_async_safe_printf("\tExternal Debugger Dump:\n");
1075                         g_async_safe_printf ("=================================================================\n");
1076                         mono_gdb_render_native_backtraces (crashed_pid);
1077                         _exit (1);
1078                 } else if (pid > 0) {
1079                         waitpid (pid, &status, 0);
1080                 } else {
1081                         // If we can't fork, do as little as possible before exiting
1082 #ifndef DISABLE_CRASH_REPORTING
1083                         output = NULL;
1084 #endif
1085                 }
1086
1087                 if (double_faulted) {
1088                         g_async_safe_printf("\nExiting early due to double fault.\n");
1089 #ifndef DISABLE_CRASH_REPORTING
1090                         mono_state_free_mem (&merp_mem);
1091 #endif
1092                         _exit (-1);
1093                 }
1094
1095 #ifndef DISABLE_CRASH_REPORTING
1096                 if (output) {
1097                         // We've already done our gdb dump and our telemetry steps. Before exiting,
1098                         // see if we can notify any attached debugger instances.
1099                         //
1100                         // At this point we are accepting that the below step might end in a crash
1101                         mini_get_dbg_callbacks ()->send_crash (output, &hashes, 0 /* wait # seconds */);
1102                 }
1103                 output = NULL;
1104                 mono_state_free_mem (&merp_mem);
1105 #endif
1106
1107         }
1108 #endif
1109 #else
1110 #ifdef HOST_ANDROID
1111         /* set DUMPABLE for this process so debuggerd can attach with ptrace(2), see:
1112         * https://android.googlesource.com/platform/bionic/+/151da681000c07da3c24cd30a3279b1ca017f452/linker/debugger.cpp#206
1113         * this has changed on later versions of Android.  Also, we don't want to
1114         * set this on start-up as DUMPABLE has security implications. */
1115         prctl (PR_SET_DUMPABLE, 1);
1116
1117         g_async_safe_printf("\nNo native Android stacktrace (see debuggerd output).\n");
1118 #endif
1119 #endif
1120 }
1121
1122 void
1123 mono_dump_native_crash_info (const char *signal, MonoContext *mctx, MONO_SIG_HANDLER_INFO_TYPE *info)
1124 {
1125         dump_native_stacktrace (signal, mctx);
1126
1127         dump_memory_around_ip (mctx);
1128 }
1129
1130 void
1131 mono_post_native_crash_handler (const char *signal, MonoContext *mctx, MONO_SIG_HANDLER_INFO_TYPE *info, gboolean crash_chaining)
1132 {
1133         if (!crash_chaining) {
1134                 /*Android abort is a fluke, it doesn't abort, it triggers another segv. */
1135 #if defined (HOST_ANDROID)
1136                 exit (-1);
1137 #else
1138                 abort ();
1139 #endif
1140         }
1141 }
1142 #endif /* !MONO_CROSS_COMPILE */
1143
1144 static gchar *gdb_path;
1145 static gchar *lldb_path;
1146
1147 void
1148 mono_init_native_crash_info (void)
1149 {
1150         gdb_path = g_find_program_in_path ("gdb");
1151         lldb_path = g_find_program_in_path ("lldb");
1152 }
1153
1154 void
1155 mono_cleanup_native_crash_info (void)
1156 {
1157         g_free (gdb_path);
1158         g_free (lldb_path);
1159 }
1160
1161 static gboolean
1162 native_stack_with_gdb (pid_t crashed_pid, const char **argv, int commands, char* commands_filename)
1163 {
1164         if (!gdb_path)
1165                 return FALSE;
1166
1167         argv [0] = gdb_path;
1168         argv [1] = "-batch";
1169         argv [2] = "-x";
1170         argv [3] = commands_filename;
1171         argv [4] = "-nx";
1172
1173         g_async_safe_fprintf (commands, "attach %ld\n", (long) crashed_pid);
1174         g_async_safe_fprintf (commands, "info threads\n");
1175         g_async_safe_fprintf (commands, "thread apply all bt\n");
1176         if (mini_get_debug_options ()->verbose_gdb) {
1177                 for (int i = 0; i < 32; ++i) {
1178                         g_async_safe_fprintf (commands, "info registers\n");
1179                         g_async_safe_fprintf (commands, "info frame\n");
1180                         g_async_safe_fprintf (commands, "info locals\n");
1181                         g_async_safe_fprintf (commands, "up\n");
1182                 }
1183         }
1184
1185         return TRUE;
1186 }
1187
1188
1189 static gboolean
1190 native_stack_with_lldb (pid_t crashed_pid, const char **argv, int commands, char* commands_filename)
1191 {
1192         if (!lldb_path)
1193                 return FALSE;
1194
1195         argv [0] = lldb_path;
1196         argv [1] = "--batch";
1197         argv [2] = "--source";
1198         argv [3] = commands_filename;
1199         argv [4] = "--no-lldbinit";
1200
1201         g_async_safe_fprintf (commands, "process attach --pid %ld\n", (long) crashed_pid);
1202         g_async_safe_fprintf (commands, "thread list\n");
1203         g_async_safe_fprintf (commands, "thread backtrace all\n");
1204         if (mini_get_debug_options ()->verbose_gdb) {
1205                 for (int i = 0; i < 32; ++i) {
1206                         g_async_safe_fprintf (commands, "reg read\n");
1207                         g_async_safe_fprintf (commands, "frame info\n");
1208                         g_async_safe_fprintf (commands, "frame variable\n");
1209                         g_async_safe_fprintf (commands, "up\n");
1210                 }
1211         }
1212         g_async_safe_fprintf (commands, "detach\n");
1213         g_async_safe_fprintf (commands, "quit\n");
1214
1215         return TRUE;
1216 }
1217
1218 void
1219 mono_gdb_render_native_backtraces (pid_t crashed_pid)
1220 {
1221 #ifdef HAVE_EXECV
1222         const char *argv [10];
1223         memset (argv, 0, sizeof (char*) * 10);
1224
1225         char commands_filename [100];
1226         commands_filename [0] = '\0';
1227         g_snprintf (commands_filename, sizeof (commands_filename), "/tmp/mono-gdb-commands.%d", crashed_pid);
1228
1229         // Create this file, overwriting if it already exists
1230         int commands_handle = g_open (commands_filename, O_TRUNC | O_WRONLY | O_CREAT, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH);
1231         if (commands_handle == -1) {
1232                 g_async_safe_printf ("Could not make debugger temp file %s\n", commands_filename);
1233                 return;
1234         }
1235
1236 #if defined(HOST_DARWIN)
1237         if (native_stack_with_lldb (crashed_pid, argv, commands_handle, commands_filename))
1238                 goto exec;
1239 #endif
1240
1241         if (native_stack_with_gdb (crashed_pid, argv, commands_handle, commands_filename))
1242                 goto exec;
1243
1244 #if !defined(HOST_DARWIN)
1245         if (native_stack_with_lldb (crashed_pid, argv, commands_handle, commands_filename))
1246                 goto exec;
1247 #endif
1248
1249         g_async_safe_printf ("mono_gdb_render_native_backtraces not supported on this platform, unable to find gdb or lldb\n");
1250
1251         close (commands_handle);
1252         unlink (commands_filename);
1253         return;
1254
1255 exec:
1256         close (commands_handle);
1257         execv (argv [0], (char**)argv);
1258
1259         _exit (-1);
1260 #else
1261         g_async_safe_printf ("mono_gdb_render_native_backtraces not supported on this platform\n");
1262 #endif // HAVE_EXECV
1263 }
1264
1265 #if !defined (__MACH__)
1266
1267 gboolean
1268 mono_thread_state_init_from_handle (MonoThreadUnwindState *tctx, MonoThreadInfo *info, void *sigctx)
1269 {
1270         g_error ("Posix systems don't support mono_thread_state_init_from_handle");
1271         return FALSE;
1272 }
1273
1274 #endif