mono/mini/mini-posix.c

   1 /*
   2  * mini-posix.c: POSIX signal handling support for Mono.
   3  *
   4  * Authors:
   5  *   Mono Team (mono-list@lists.ximian.com)
   6  *
   7  * Copyright 2001-2003 Ximian, Inc.
   8  * Copyright 2003-2008 Ximian, Inc.
   9  * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
  10  *
  11  * See LICENSE for licensing information.
  12  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  13  */
  14 #include <config.h>
  15 #include <signal.h>
  16 #ifdef HAVE_ALLOCA_H
  17 #include <alloca.h>
  18 #endif
  19 #ifdef HAVE_UNISTD_H
  20 #include <unistd.h>
  21 #endif
  22 #include <math.h>
  23 #ifdef HAVE_SYS_TIME_H
  24 #include <sys/time.h>
  25 #endif
  26 #ifdef HAVE_SYS_SYSCALL_H
  27 #include <sys/syscall.h>
  28 #endif
  29 #include <errno.h>
  30 #include <sched.h>
  31
  32 #include <mono/metadata/assembly.h>
  33 #include <mono/metadata/loader.h>
  34 #include <mono/metadata/tabledefs.h>
  35 #include <mono/metadata/class.h>
  36 #include <mono/metadata/object.h>
  37 #include <mono/metadata/tokentype.h>
  38 #include <mono/metadata/tabledefs.h>
  39 #include <mono/metadata/threads.h>
  40 #include <mono/metadata/appdomain.h>
  41 #include <mono/metadata/debug-helpers.h>
  42 #include <mono/io-layer/io-layer.h>
  43 #include "mono/metadata/profiler.h"
  44 #include <mono/metadata/profiler-private.h>
  45 #include <mono/metadata/mono-config.h>
  46 #include <mono/metadata/environment.h>
  47 #include <mono/metadata/mono-debug.h>
  48 #include <mono/metadata/gc-internals.h>
  49 #include <mono/metadata/threads-types.h>
  50 #include <mono/metadata/verify.h>
  51 #include <mono/metadata/verify-internals.h>
  52 #include <mono/metadata/mempool-internals.h>
  53 #include <mono/metadata/attach.h>
  54 #include <mono/utils/mono-math.h>
  55 #include <mono/utils/mono-compiler.h>
  56 #include <mono/utils/mono-counters.h>
  57 #include <mono/utils/mono-logger-internals.h>
  58 #include <mono/utils/mono-mmap.h>
  59 #include <mono/utils/dtrace.h>
  60 #include <mono/utils/mono-signal-handler.h>
  61 #include <mono/utils/mono-threads.h>
  62 #include <mono/utils/mono-threads-posix-signals.h>
  63
  64 #include "mini.h"
  65 #include <string.h>
  66 #include <ctype.h>
  67 #include "trace.h"
  68 #include "version.h"
  69 #include "debugger-agent.h"
  70
  71 #include "jit-icalls.h"
  72
  73 #ifdef PLATFORM_MACOSX
  74 #include <mach/mach.h>
  75 #include <mach/mach_time.h>
  76 #include <mach/clock.h>
  77 #endif
  78
  79 #if defined(__native_client__) || defined(HOST_WATCHOS)
  80
  81 void
  82 mono_runtime_setup_stat_profiler (void)
  83 {
  84         printf("WARNING: mono_runtime_setup_stat_profiler() called!\n");
  85 }
  86
  87
  88 void
  89 mono_runtime_shutdown_stat_profiler (void)
  90 {
  91 }
  92
  93
  94 gboolean
  95 MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
  96 {
  97         return FALSE;
  98 }
  99
 100 #ifndef PLATFORM_MACOSX
 101 void
 102 mono_runtime_install_handlers (void)
 103 {
 104 }
 105 #endif
 106
 107 void
 108 mono_runtime_posix_install_handlers(void)
 109 {
 110         /* we still need to ignore SIGPIPE */
 111         signal (SIGPIPE, SIG_IGN);
 112 }
 113
 114 void
 115 mono_runtime_shutdown_handlers (void)
 116 {
 117 }
 118
 119 void
 120 mono_runtime_cleanup_handlers (void)
 121 {
 122 }
 123
 124 #if !defined(PLATFORM_MACOSX)
 125 pid_t
 126 mono_runtime_syscall_fork (void)
 127 {
 128         g_assert_not_reached();
 129         return 0;
 130 }
 131
 132 void
 133 mono_gdb_render_native_backtraces (pid_t crashed_pid)
 134 {
 135 }
 136 #endif
 137
 138 #else
 139
 140 static GHashTable *mono_saved_signal_handlers = NULL;
 141
 142 static struct sigaction *
 143 get_saved_signal_handler (int signo, gboolean remove)
 144 {
 145         if (mono_saved_signal_handlers) {
 146                 /* The hash is only modified during startup, so no need for locking */
 147                 struct sigaction *handler = g_hash_table_lookup (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
 148                 if (remove && handler)
 149                         g_hash_table_remove (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
 150                 return handler;
 151         }
 152         return NULL;
 153 }
 154
 155 static void
 156 save_old_signal_handler (int signo, struct sigaction *old_action)
 157 {
 158         struct sigaction *handler_to_save = (struct sigaction *)g_malloc (sizeof (struct sigaction));
 159
 160         mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_CONFIG,
 161                                 "Saving old signal handler for signal %d.", signo);
 162
 163         if (! (old_action->sa_flags & SA_SIGINFO)) {
 164                 handler_to_save->sa_handler = old_action->sa_handler;
 165         } else {
 166 #ifdef MONO_ARCH_USE_SIGACTION
 167                 handler_to_save->sa_sigaction = old_action->sa_sigaction;
 168 #endif /* MONO_ARCH_USE_SIGACTION */
 169         }
 170         handler_to_save->sa_mask = old_action->sa_mask;
 171         handler_to_save->sa_flags = old_action->sa_flags;
 172
 173         if (!mono_saved_signal_handlers)
 174                 mono_saved_signal_handlers = g_hash_table_new_full (NULL, NULL, NULL, g_free);
 175         g_hash_table_insert (mono_saved_signal_handlers, GINT_TO_POINTER (signo), handler_to_save);
 176 }
 177
 178 static void
 179 free_saved_signal_handlers (void)
 180 {
 181         if (mono_saved_signal_handlers) {
 182                 g_hash_table_destroy (mono_saved_signal_handlers);
 183                 mono_saved_signal_handlers = NULL;
 184         }
 185 }
 186
 187 /*
 188  * mono_chain_signal:
 189  *
 190  *   Call the original signal handler for the signal given by the arguments, which
 191  * should be the same as for a signal handler. Returns TRUE if the original handler
 192  * was called, false otherwise.
 193  */
 194 gboolean
 195 MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
 196 {
 197         int signal = MONO_SIG_HANDLER_GET_SIGNO ();
 198         struct sigaction *saved_handler = (struct sigaction *)get_saved_signal_handler (signal, FALSE);
 199
 200         if (saved_handler && saved_handler->sa_handler) {
 201                 if (!(saved_handler->sa_flags & SA_SIGINFO)) {
 202                         saved_handler->sa_handler (signal);
 203                 } else {
 204 #ifdef MONO_ARCH_USE_SIGACTION
 205                         saved_handler->sa_sigaction (MONO_SIG_HANDLER_PARAMS);
 206 #endif /* MONO_ARCH_USE_SIGACTION */
 207                 }
 208                 return TRUE;
 209         }
 210         return FALSE;
 211 }
 212
 213 MONO_SIG_HANDLER_FUNC (static, sigabrt_signal_handler)
 214 {
 215         MonoJitInfo *ji = NULL;
 216         MONO_SIG_HANDLER_INFO_TYPE *info = MONO_SIG_HANDLER_GET_INFO ();
 217         MONO_SIG_HANDLER_GET_CONTEXT;
 218
 219         if (mono_thread_internal_current ())
 220                 ji = mono_jit_info_table_find_internal (mono_domain_get (), (char *)mono_arch_ip_from_context (ctx), TRUE, TRUE);
 221         if (!ji) {
 222         if (mono_chain_signal (MONO_SIG_HANDLER_PARAMS))
 223                         return;
 224                 mono_handle_native_sigsegv (SIGABRT, ctx, info);
 225         }
 226 }
 227
 228 #if defined(__i386__) || defined(__x86_64__)
 229 #define FULL_STAT_PROFILER_BACKTRACE 1
 230 #define CURRENT_FRAME_GET_BASE_POINTER(f) (* (gpointer*)(f))
 231 #define CURRENT_FRAME_GET_RETURN_ADDRESS(f) (* (((gpointer*)(f)) + 1))
 232 #if MONO_ARCH_STACK_GROWS_UP
 233 #define IS_BEFORE_ON_STACK <
 234 #define IS_AFTER_ON_STACK >
 235 #else
 236 #define IS_BEFORE_ON_STACK >
 237 #define IS_AFTER_ON_STACK <
 238 #endif
 239 #else
 240 #define FULL_STAT_PROFILER_BACKTRACE 0
 241 #endif
 242
 243 #if (defined (USE_POSIX_BACKEND) && defined (SIGRTMIN)) || defined (SIGPROF)
 244 #define HAVE_PROFILER_SIGNAL
 245 #endif
 246
 247 #ifdef HAVE_PROFILER_SIGNAL
 248
 249 static void
 250 per_thread_profiler_hit (void *ctx)
 251 {
 252         int call_chain_depth = mono_profiler_stat_get_call_chain_depth ();
 253         MonoProfilerCallChainStrategy call_chain_strategy = mono_profiler_stat_get_call_chain_strategy ();
 254
 255         if (call_chain_depth == 0) {
 256                 mono_profiler_stat_hit ((guchar *)mono_arch_ip_from_context (ctx), ctx);
 257         } else {
 258                 MonoJitTlsData *jit_tls = (MonoJitTlsData *)mono_native_tls_get_value (mono_jit_tls_id);
 259                 int current_frame_index = 1;
 260                 MonoContext mono_context;
 261                 guchar *ips [call_chain_depth + 1];
 262
 263                 mono_sigctx_to_monoctx (ctx, &mono_context);
 264                 ips [0] = (guchar *)MONO_CONTEXT_GET_IP (&mono_context);
 265
 266                 if (jit_tls != NULL) {
 267                         if (call_chain_strategy == MONO_PROFILER_CALL_CHAIN_NATIVE) {
 268 #if FULL_STAT_PROFILER_BACKTRACE
 269                         guchar *current_frame;
 270                         guchar *stack_bottom;
 271                         guchar *stack_top;
 272
 273                         stack_bottom = (guchar *)jit_tls->end_of_stack;
 274                         stack_top = (guchar *)MONO_CONTEXT_GET_SP (&mono_context);
 275                         current_frame = (guchar *)MONO_CONTEXT_GET_BP (&mono_context);
 276
 277                         while ((current_frame_index <= call_chain_depth) &&
 278                                         (stack_bottom IS_BEFORE_ON_STACK (guchar*) current_frame) &&
 279                                         ((guchar*) current_frame IS_BEFORE_ON_STACK stack_top)) {
 280                                 ips [current_frame_index] = (guchar *)CURRENT_FRAME_GET_RETURN_ADDRESS (current_frame);
 281                                 current_frame_index ++;
 282                                 stack_top = current_frame;
 283                                 current_frame = (guchar *)CURRENT_FRAME_GET_BASE_POINTER (current_frame);
 284                         }
 285 #else
 286                                 call_chain_strategy = MONO_PROFILER_CALL_CHAIN_GLIBC;
 287 #endif
 288                         }
 289
 290                         if (call_chain_strategy == MONO_PROFILER_CALL_CHAIN_GLIBC) {
 291 #if GLIBC_PROFILER_BACKTRACE
 292                                 current_frame_index = backtrace ((void**) & ips [1], call_chain_depth);
 293 #else
 294                                 call_chain_strategy = MONO_PROFILER_CALL_CHAIN_MANAGED;
 295 #endif
 296                         }
 297
 298                         if (call_chain_strategy == MONO_PROFILER_CALL_CHAIN_MANAGED) {
 299                                 MonoDomain *domain = mono_domain_get ();
 300                                 if (domain != NULL) {
 301                                         MonoLMF *lmf = NULL;
 302                                         MonoJitInfo *ji;
 303                                         MonoJitInfo res;
 304                                         MonoContext new_mono_context;
 305                                         int native_offset;
 306                                         ji = mono_find_jit_info (domain, jit_tls, &res, NULL, &mono_context,
 307                                                         &new_mono_context, NULL, &lmf, &native_offset, NULL);
 308                                         while ((ji != NULL) && (current_frame_index <= call_chain_depth)) {
 309                                                 ips [current_frame_index] = (guchar *)MONO_CONTEXT_GET_IP (&new_mono_context);
 310                                                 current_frame_index ++;
 311                                                 mono_context = new_mono_context;
 312                                                 ji = mono_find_jit_info (domain, jit_tls, &res, NULL, &mono_context,
 313                                                                 &new_mono_context, NULL, &lmf, &native_offset, NULL);
 314                                         }
 315                                 }
 316                         }
 317                 }
 318
 319                 mono_profiler_stat_call_chain (current_frame_index, & ips [0], ctx);
 320         }
 321 }
 322
 323 static MonoNativeThreadId sampling_thread;
 324
 325 static gint32 profiler_signals_sent;
 326 static gint32 profiler_signals_received;
 327 static gint32 profiler_signals_accepted;
 328 static gint32 profiler_interrupt_signals_received;
 329
 330 MONO_SIG_HANDLER_FUNC (static, profiler_signal_handler)
 331 {
 332         int old_errno = errno;
 333         int hp_save_index;
 334         MONO_SIG_HANDLER_GET_CONTEXT;
 335
 336         /* See the comment in mono_runtime_shutdown_stat_profiler (). */
 337         if (mono_native_thread_id_get () == sampling_thread) {
 338 #ifdef HAVE_CLOCK_NANOSLEEP
 339                 if (mono_profiler_get_sampling_mode () == MONO_PROFILER_STAT_MODE_PROCESS) {
 340                         InterlockedIncrement (&profiler_interrupt_signals_received);
 341                         return;
 342                 }
 343 #endif
 344
 345                 g_error ("%s: Unexpected profiler signal received by the sampler thread", __func__);
 346         }
 347
 348         InterlockedIncrement (&profiler_signals_received);
 349
 350         if (mono_thread_info_get_small_id () == -1)
 351                 return; //an non-attached thread got the signal
 352
 353         if (!mono_domain_get () || !mono_native_tls_get_value (mono_jit_tls_id))
 354                 return; //thread in the process of dettaching
 355
 356         InterlockedIncrement (&profiler_signals_accepted);
 357
 358         hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
 359
 360         mono_thread_info_set_is_async_context (TRUE);
 361         per_thread_profiler_hit (ctx);
 362         mono_thread_info_set_is_async_context (FALSE);
 363
 364         mono_hazard_pointer_restore_for_signal_handler (hp_save_index);
 365         errno = old_errno;
 366
 367         mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
 368 }
 369
 370 #endif
 371
 372 MONO_SIG_HANDLER_FUNC (static, sigquit_signal_handler)
 373 {
 374         gboolean res;
 375
 376         /* We use this signal to start the attach agent too */
 377         res = mono_attach_start ();
 378         if (res)
 379                 return;
 380
 381         mono_threads_request_thread_dump ();
 382
 383         mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
 384 }
 385
 386 MONO_SIG_HANDLER_FUNC (static, sigusr2_signal_handler)
 387 {
 388         gboolean enabled = mono_trace_is_enabled ();
 389
 390         mono_trace_enable (!enabled);
 391
 392         mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
 393 }
 394
 395 static void
 396 add_signal_handler (int signo, gpointer handler, int flags)
 397 {
 398         struct sigaction sa;
 399         struct sigaction previous_sa;
 400
 401 #ifdef MONO_ARCH_USE_SIGACTION
 402         sa.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
 403         sigemptyset (&sa.sa_mask);
 404         sa.sa_flags = SA_SIGINFO | flags;
 405 #ifdef MONO_ARCH_SIGSEGV_ON_ALTSTACK
 406
 407 /*Apple likes to deliver SIGBUS for *0 */
 408 #ifdef PLATFORM_MACOSX
 409         if (signo == SIGSEGV || signo == SIGBUS) {
 410 #else
 411         if (signo == SIGSEGV) {
 412 #endif
 413                 sa.sa_flags |= SA_ONSTACK;
 414
 415                 /*
 416                  * libgc will crash when trying to do stack marking for threads which are on
 417                  * an altstack, so delay the suspend signal after the signal handler has
 418                  * executed.
 419                  */
 420                 if (mono_gc_get_suspend_signal () != -1)
 421                         sigaddset (&sa.sa_mask, mono_gc_get_suspend_signal ());
 422         }
 423 #endif
 424         if (signo == SIGSEGV) {
 425                 /*
 426                  * Delay abort signals while handling SIGSEGVs since they could go unnoticed.
 427                  */
 428                 sigset_t block_mask;
 429
 430                 sigemptyset (&block_mask);
 431         }
 432 #else
 433         sa.sa_handler = handler;
 434         sigemptyset (&sa.sa_mask);
 435         sa.sa_flags = flags;
 436 #endif
 437         g_assert (sigaction (signo, &sa, &previous_sa) != -1);
 438
 439         /* if there was already a handler in place for this signal, store it */
 440         if (! (previous_sa.sa_flags & SA_SIGINFO) &&
 441                         (SIG_DFL == previous_sa.sa_handler)) {
 442                 /* it there is no sa_sigaction function and the sa_handler is default, we can safely ignore this */
 443         } else {
 444                 if (mono_do_signal_chaining)
 445                         save_old_signal_handler (signo, &previous_sa);
 446         }
 447 }
 448
 449 static void
 450 remove_signal_handler (int signo)
 451 {
 452         struct sigaction sa;
 453         struct sigaction *saved_action = get_saved_signal_handler (signo, TRUE);
 454
 455         if (!saved_action) {
 456                 sa.sa_handler = SIG_DFL;
 457                 sigemptyset (&sa.sa_mask);
 458                 sa.sa_flags = 0;
 459
 460                 sigaction (signo, &sa, NULL);
 461         } else {
 462                 g_assert (sigaction (signo, saved_action, NULL) != -1);
 463         }
 464 }
 465
 466 void
 467 mono_runtime_posix_install_handlers (void)
 468 {
 469
 470         sigset_t signal_set;
 471
 472         if (mini_get_debug_options ()->handle_sigint)
 473                 add_signal_handler (SIGINT, mono_sigint_signal_handler, SA_RESTART);
 474
 475         add_signal_handler (SIGFPE, mono_sigfpe_signal_handler, 0);
 476         add_signal_handler (SIGQUIT, sigquit_signal_handler, SA_RESTART);
 477         add_signal_handler (SIGILL, mono_sigill_signal_handler, 0);
 478         add_signal_handler (SIGBUS, mono_sigsegv_signal_handler, 0);
 479         if (mono_jit_trace_calls != NULL)
 480                 add_signal_handler (SIGUSR2, sigusr2_signal_handler, SA_RESTART);
 481
 482         /* it seems to have become a common bug for some programs that run as parents
 483          * of many processes to block signal delivery for real time signals.
 484          * We try to detect and work around their breakage here.
 485          */
 486         sigemptyset (&signal_set);
 487         if (mono_gc_get_suspend_signal () != -1)
 488                 sigaddset (&signal_set, mono_gc_get_suspend_signal ());
 489         if (mono_gc_get_restart_signal () != -1)
 490                 sigaddset (&signal_set, mono_gc_get_restart_signal ());
 491         sigaddset (&signal_set, SIGCHLD);
 492         sigprocmask (SIG_UNBLOCK, &signal_set, NULL);
 493
 494         signal (SIGPIPE, SIG_IGN);
 495
 496         add_signal_handler (SIGABRT, sigabrt_signal_handler, 0);
 497
 498         /* catch SIGSEGV */
 499         add_signal_handler (SIGSEGV, mono_sigsegv_signal_handler, 0);
 500 }
 501
 502 #ifndef PLATFORM_MACOSX
 503 void
 504 mono_runtime_install_handlers (void)
 505 {
 506         mono_runtime_posix_install_handlers ();
 507 }
 508 #endif
 509
 510 void
 511 mono_runtime_cleanup_handlers (void)
 512 {
 513         if (mini_get_debug_options ()->handle_sigint)
 514                 remove_signal_handler (SIGINT);
 515
 516         remove_signal_handler (SIGFPE);
 517         remove_signal_handler (SIGQUIT);
 518         remove_signal_handler (SIGILL);
 519         remove_signal_handler (SIGBUS);
 520         if (mono_jit_trace_calls != NULL)
 521                 remove_signal_handler (SIGUSR2);
 522
 523         remove_signal_handler (SIGABRT);
 524
 525         remove_signal_handler (SIGSEGV);
 526
 527         free_saved_signal_handlers ();
 528 }
 529
 530 #ifdef HAVE_PROFILER_SIGNAL
 531
 532 static volatile gint32 sampling_thread_running;
 533
 534 #ifdef PLATFORM_MACOSX
 535
 536 static clock_serv_t sampling_clock_service;
 537
 538 static void
 539 clock_init (void)
 540 {
 541         kern_return_t ret;
 542
 543         do {
 544                 ret = host_get_clock_service (mach_host_self (), SYSTEM_CLOCK, &sampling_clock_service);
 545         } while (ret == KERN_ABORTED);
 546
 547         if (ret != KERN_SUCCESS)
 548                 g_error ("%s: host_get_clock_service () returned %d", __func__, ret);
 549 }
 550
 551 static void
 552 clock_cleanup (void)
 553 {
 554         kern_return_t ret;
 555
 556         do {
 557                 ret = mach_port_deallocate (mach_task_self (), sampling_clock_service);
 558         } while (ret == KERN_ABORTED);
 559
 560         if (ret != KERN_SUCCESS)
 561                 g_error ("%s: mach_port_deallocate () returned %d", __func__, ret);
 562 }
 563
 564 static guint64
 565 clock_get_time_ns (void)
 566 {
 567         kern_return_t ret;
 568         mach_timespec_t mach_ts;
 569
 570         do {
 571                 ret = clock_get_time (sampling_clock_service, &mach_ts);
 572         } while (ret == KERN_ABORTED);
 573
 574         if (ret != KERN_SUCCESS)
 575                 g_error ("%s: clock_get_time () returned %d", __func__, ret);
 576
 577         return ((guint64) mach_ts.tv_sec * 1000000000) + (guint64) mach_ts.tv_nsec;
 578 }
 579
 580 static void
 581 clock_sleep_ns_abs (guint64 ns_abs)
 582 {
 583         kern_return_t ret;
 584         mach_timespec_t then, remain_unused;
 585
 586         then.tv_sec = ns_abs / 1000000000;
 587         then.tv_nsec = ns_abs % 1000000000;
 588
 589         do {
 590                 ret = clock_sleep (sampling_clock_service, TIME_ABSOLUTE, then, &remain_unused);
 591
 592                 if (ret != KERN_SUCCESS && ret != KERN_ABORTED)
 593                         g_error ("%s: clock_sleep () returned %d", __func__, ret);
 594         } while (ret == KERN_ABORTED && InterlockedRead (&sampling_thread_running));
 595 }
 596
 597 #else
 598
 599 clockid_t sampling_posix_clock;
 600
 601 static void
 602 clock_init (void)
 603 {
 604         switch (mono_profiler_get_sampling_mode ()) {
 605         case MONO_PROFILER_STAT_MODE_PROCESS:
 606 #ifdef HAVE_CLOCK_NANOSLEEP
 607                 /*
 608                  * If we don't have clock_nanosleep (), measuring the process time
 609                  * makes very little sense as we can only use nanosleep () to sleep on
 610                  * real time.
 611                  */
 612                 sampling_posix_clock = CLOCK_PROCESS_CPUTIME_ID;
 613                 break;
 614 #endif
 615         case MONO_PROFILER_STAT_MODE_REAL: sampling_posix_clock = CLOCK_MONOTONIC; break;
 616         default: g_assert_not_reached (); break;
 617         }
 618 }
 619
 620 static void
 621 clock_cleanup (void)
 622 {
 623 }
 624
 625 static guint64
 626 clock_get_time_ns (void)
 627 {
 628         struct timespec ts;
 629
 630         if (clock_gettime (sampling_posix_clock, &ts) == -1)
 631                 g_error ("%s: clock_gettime () returned -1, errno = %d", __func__, errno);
 632
 633         return ((guint64) ts.tv_sec * 1000000000) + (guint64) ts.tv_nsec;
 634 }
 635
 636 static void
 637 clock_sleep_ns_abs (guint64 ns_abs)
 638 {
 639 #ifdef HAVE_CLOCK_NANOSLEEP
 640         int ret;
 641         struct timespec then;
 642
 643         then.tv_sec = ns_abs / 1000000000;
 644         then.tv_nsec = ns_abs % 1000000000;
 645
 646         do {
 647                 ret = clock_nanosleep (sampling_posix_clock, TIMER_ABSTIME, &then, NULL);
 648
 649                 if (ret != 0 && ret != EINTR)
 650                         g_error ("%s: clock_nanosleep () returned %d", __func__, ret);
 651         } while (ret == EINTR && InterlockedRead (&sampling_thread_running));
 652 #else
 653         int ret;
 654         gint64 diff;
 655         struct timespec req;
 656
 657         /*
 658          * What follows is a crude attempt at emulating clock_nanosleep () on OSs
 659          * which don't provide it (e.g. FreeBSD).
 660          *
 661          * The problem with nanosleep () is that if it is interrupted by a signal,
 662          * time will drift as a result of having to restart the call after the
 663          * signal handler has finished. For this reason, we avoid using the rem
 664          * argument of nanosleep (). Instead, before every nanosleep () call, we
 665          * check if enough time has passed to satisfy the sleep request. If yes, we
 666          * simply return. If not, we calculate the difference and do another sleep.
 667          *
 668          * This should reduce the amount of drift that happens because we account
 669          * for the time spent executing the signal handler, which nanosleep () is
 670          * not guaranteed to do for the rem argument.
 671          *
 672          * The downside to this approach is that it is slightly expensive: We have
 673          * to make an extra system call to retrieve the current time whenever we're
 674          * going to restart a nanosleep () call. This is unlikely to be a problem
 675          * in practice since the sampling thread won't be receiving many signals in
 676          * the first place (it's a tools thread, so no STW), and because typical
 677          * sleep periods for the thread are many orders of magnitude bigger than
 678          * the time it takes to actually perform that system call (just a few
 679          * nanoseconds).
 680          */
 681         do {
 682                 diff = (gint64) ns_abs - (gint64) clock_get_time_ns ();
 683
 684                 if (diff <= 0)
 685                         break;
 686
 687                 req.tv_sec = diff / 1000000000;
 688                 req.tv_nsec = diff % 1000000000;
 689
 690                 if ((ret = nanosleep (&req, NULL)) == -1 && errno != EINTR)
 691                         g_error ("%s: nanosleep () returned -1, errno = %d", __func__, errno);
 692         } while (ret == -1 && InterlockedRead (&sampling_thread_running));
 693 #endif
 694 }
 695
 696 #endif
 697
 698 static int profiler_signal;
 699 static volatile gint32 sampling_thread_exiting;
 700
 701 static mono_native_thread_return_t
 702 sampling_thread_func (void *data)
 703 {
 704         mono_threads_attach_tools_thread ();
 705         mono_native_thread_set_name (mono_native_thread_id_get (), "Profiler sampler");
 706
 707         gint64 rate = 1000000000 / mono_profiler_get_sampling_rate ();
 708
 709         int old_policy;
 710         struct sched_param old_sched;
 711         pthread_getschedparam (pthread_self (), &old_policy, &old_sched);
 712
 713         /*
 714          * Attempt to switch the thread to real time scheduling. This will not
 715          * necessarily work on all OSs; for example, most Linux systems will give
 716          * us EPERM here unless configured to allow this.
 717          *
 718          * TODO: This does not work on Mac (and maybe some other OSs). On Mac, we
 719          * have to use the Mach thread policy routines to switch to real-time
 720          * scheduling. This is quite tricky as we need to specify how often we'll
 721          * be doing work (easy), the normal processing time needed (also easy),
 722          * and the maximum amount of processing time needed (hard). This is
 723          * further complicated by the fact that if we misbehave and take too long
 724          * to do our work, the kernel may knock us back down to the normal thread
 725          * scheduling policy without telling us.
 726          */
 727         struct sched_param sched = { .sched_priority = sched_get_priority_max (SCHED_FIFO) };
 728         pthread_setschedparam (pthread_self (), SCHED_FIFO, &sched);
 729
 730         clock_init ();
 731
 732         guint64 sleep = clock_get_time_ns ();
 733
 734         while (InterlockedRead (&sampling_thread_running)) {
 735                 sleep += rate;
 736
 737                 FOREACH_THREAD_SAFE (info) {
 738                         /* info should never be this thread as we're a tools thread. */
 739                         g_assert (mono_thread_info_get_tid (info) != mono_native_thread_id_get ());
 740
 741                         mono_threads_pthread_kill (info, profiler_signal);
 742                         InterlockedIncrement (&profiler_signals_sent);
 743                 } FOREACH_THREAD_SAFE_END
 744
 745                 clock_sleep_ns_abs (sleep);
 746         }
 747
 748         InterlockedWrite (&sampling_thread_exiting, 1);
 749
 750         clock_cleanup ();
 751
 752         pthread_setschedparam (pthread_self (), old_policy, &old_sched);
 753
 754         mono_thread_info_detach ();
 755
 756         return NULL;
 757 }
 758
 759 void
 760 mono_runtime_shutdown_stat_profiler (void)
 761 {
 762         InterlockedWrite (&sampling_thread_running, 0);
 763
 764 #ifdef HAVE_CLOCK_NANOSLEEP
 765         /*
 766          * There is a slight problem when we're using CLOCK_PROCESS_CPUTIME_ID: If
 767          * we're shutting down and there's largely no activity in the process other
 768          * than waiting for the sampler thread to shut down, it can take upwards of
 769          * 20 seconds (depending on a lot of factors) for us to shut down because
 770          * the sleep progresses very slowly as a result of the low CPU activity.
 771          *
 772          * We fix this by repeatedly sending the profiler signal to the sampler
 773          * thread in order to interrupt the sleep. clock_sleep_ns_abs () will check
 774          * sampling_thread_running upon an interrupt and return immediately if it's
 775          * zero. profiler_signal_handler () has a special case to ignore the signal
 776          * for the sampler thread.
 777          *
 778          * We do not need to do this on platforms where we use a regular sleep
 779          * based on a monotonic clock. The sleep will return in a reasonable amount
 780          * of time in those cases.
 781          */
 782         if (mono_profiler_get_sampling_mode () == MONO_PROFILER_STAT_MODE_PROCESS) {
 783                 MonoThreadInfo *info;
 784
 785                 // Did it shut down already?
 786                 if ((info = mono_thread_info_lookup (sampling_thread))) {
 787                         while (!InterlockedRead (&sampling_thread_exiting)) {
 788                                 mono_threads_pthread_kill (info, profiler_signal);
 789                                 mono_thread_info_usleep (10 * 1000 /* 10ms */);
 790                         }
 791
 792                         // Make sure info can be freed.
 793                         mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
 794                 }
 795         }
 796 #endif
 797
 798         pthread_join (sampling_thread, NULL);
 799
 800         /*
 801          * We can't safely remove the signal handler because we have no guarantee
 802          * that all pending signals have been delivered at this point. This should
 803          * not really be a problem anyway.
 804          */
 805         //remove_signal_handler (profiler_signal);
 806 }
 807
 808 void
 809 mono_runtime_setup_stat_profiler (void)
 810 {
 811         /*
 812          * Use a real-time signal when possible. This gives us roughly a 99% signal
 813          * delivery rate in all cases. On the other hand, using a regular signal
 814          * tends to result in awful delivery rates when the application is heavily
 815          * loaded.
 816          *
 817          * We avoid real-time signals on Android as they're super broken in certain
 818          * API levels (too small sigset_t, nonsensical SIGRTMIN/SIGRTMAX values,
 819          * etc).
 820          *
 821          * TODO: On Mac, we should explore using the Mach thread suspend/resume
 822          * functions and doing the stack walk from the sampling thread. This would
 823          * get us a 100% sampling rate. However, this may interfere with the GC's
 824          * STW logic. Could perhaps be solved by taking the suspend lock.
 825          */
 826 #if defined (USE_POSIX_BACKEND) && defined (SIGRTMIN) && !defined (PLATFORM_ANDROID)
 827         /* Just take the first real-time signal we can get. */
 828         profiler_signal = mono_threads_posix_signal_search_alternative (-1);
 829 #else
 830         profiler_signal = SIGPROF;
 831 #endif
 832
 833         add_signal_handler (profiler_signal, profiler_signal_handler, SA_RESTART);
 834
 835         mono_counters_register ("Sampling signals sent", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_sent);
 836         mono_counters_register ("Sampling signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_received);
 837         mono_counters_register ("Sampling signals accepted", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_accepted);
 838         mono_counters_register ("Shutdown signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_interrupt_signals_received);
 839
 840         InterlockedWrite (&sampling_thread_running, 1);
 841         mono_native_thread_create (&sampling_thread, sampling_thread_func, NULL);
 842 }
 843
 844 #else
 845
 846 void
 847 mono_runtime_shutdown_stat_profiler (void)
 848 {
 849 }
 850
 851 void
 852 mono_runtime_setup_stat_profiler (void)
 853 {
 854 }
 855
 856 #endif
 857
 858 #if !defined(PLATFORM_MACOSX)
 859 pid_t
 860 mono_runtime_syscall_fork ()
 861 {
 862 #if defined(PLATFORM_ANDROID)
 863         /* SYS_fork is defined to be __NR_fork which is not defined in some ndk versions */
 864         g_assert_not_reached ();
 865         return 0;
 866 #elif defined(SYS_fork)
 867         return (pid_t) syscall (SYS_fork);
 868 #else
 869         g_assert_not_reached ();
 870         return 0;
 871 #endif
 872 }
 873
 874 void
 875 mono_gdb_render_native_backtraces (pid_t crashed_pid)
 876 {
 877         const char *argv [9];
 878         char template_ [] = "/tmp/mono-lldb-commands.XXXXXX";
 879         char buf1 [128];
 880         FILE *commands;
 881         gboolean using_lldb = FALSE;
 882
 883         argv [0] = g_find_program_in_path ("gdb");
 884         if (argv [0] == NULL) {
 885                 argv [0] = g_find_program_in_path ("lldb");
 886                 using_lldb = TRUE;
 887         }
 888
 889         if (argv [0] == NULL)
 890                 return;
 891
 892         if (using_lldb) {
 893                 if (mkstemp (template_) == -1)
 894                         return;
 895
 896                 commands = fopen (template_, "w");
 897
 898                 fprintf (commands, "process attach --pid %ld\n", (long) crashed_pid);
 899                 fprintf (commands, "thread list\n");
 900                 fprintf (commands, "thread backtrace all\n");
 901                 fprintf (commands, "detach\n");
 902                 fprintf (commands, "quit\n");
 903
 904                 fflush (commands);
 905                 fclose (commands);
 906
 907                 argv [1] = "--source";
 908                 argv [2] = template_;
 909                 argv [3] = 0;
 910         } else {
 911                 argv [1] = "-ex";
 912                 sprintf (buf1, "attach %ld", (long) crashed_pid);
 913                 argv [2] = buf1;
 914                 argv [3] = "--ex";
 915                 argv [4] = "info threads";
 916                 argv [5] = "--ex";
 917                 argv [6] = "thread apply all bt";
 918                 argv [7] = "--batch";
 919                 argv [8] = 0;
 920         }
 921
 922         execv (argv [0], (char**)argv);
 923
 924         if (using_lldb)
 925                 unlink (template_);
 926 }
 927 #endif
 928 #endif /* __native_client__ */
 929
 930 #if !defined (__MACH__)
 931
 932 gboolean
 933 mono_thread_state_init_from_handle (MonoThreadUnwindState *tctx, MonoThreadInfo *info)
 934 {
 935         g_error ("Posix systems don't support mono_thread_state_init_from_handle");
 936         return FALSE;
 937 }
 938
 939 #endif