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