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 #include <math.h>
24 #ifdef HAVE_SYS_TIME_H
25 #include <sys/time.h>
26 #endif
27 #ifdef HAVE_SYS_SYSCALL_H
28 #include <sys/syscall.h>
29 #endif
30 #include <errno.h>
31 #include <sched.h>
32
33 #include <mono/metadata/assembly.h>
34 #include <mono/metadata/loader.h>
35 #include <mono/metadata/tabledefs.h>
36 #include <mono/metadata/class.h>
37 #include <mono/metadata/object.h>
38 #include <mono/metadata/tokentype.h>
39 #include <mono/metadata/tabledefs.h>
40 #include <mono/metadata/threads.h>
41 #include <mono/metadata/appdomain.h>
42 #include <mono/metadata/debug-helpers.h>
43 #include <mono/metadata/profiler-private.h>
44 #include <mono/metadata/mono-config.h>
45 #include <mono/metadata/environment.h>
46 #include <mono/metadata/mono-debug.h>
47 #include <mono/metadata/gc-internals.h>
48 #include <mono/metadata/threads-types.h>
49 #include <mono/metadata/verify.h>
50 #include <mono/metadata/verify-internals.h>
51 #include <mono/metadata/mempool-internals.h>
52 #include <mono/metadata/attach.h>
53 #include <mono/utils/mono-math.h>
54 #include <mono/utils/mono-compiler.h>
55 #include <mono/utils/mono-counters.h>
56 #include <mono/utils/mono-logger-internals.h>
57 #include <mono/utils/mono-mmap.h>
58 #include <mono/utils/dtrace.h>
59 #include <mono/utils/mono-signal-handler.h>
60 #include <mono/utils/mono-threads.h>
61
62 #include "mini.h"
63 #include <string.h>
64 #include <ctype.h>
65 #include "trace.h"
66 #include "version.h"
67 #include "debugger-agent.h"
68 #include "mini-runtime.h"
69 #include "jit-icalls.h"
70
71 #ifdef HOST_DARWIN
72 #include <mach/mach.h>
73 #include <mach/mach_time.h>
74 #include <mach/clock.h>
75 #endif
76
77 #if defined(HOST_WATCHOS)
78
79 void
mono_runtime_setup_stat_profiler(void)80 mono_runtime_setup_stat_profiler (void)
81 {
82 printf("WARNING: mono_runtime_setup_stat_profiler() called!\n");
83 }
84
85
86 void
mono_runtime_shutdown_stat_profiler(void)87 mono_runtime_shutdown_stat_profiler (void)
88 {
89 }
90
91
92 gboolean
MONO_SIG_HANDLER_SIGNATURE(mono_chain_signal)93 MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
94 {
95 return FALSE;
96 }
97
98 #ifndef HOST_DARWIN
99 void
mono_runtime_install_handlers(void)100 mono_runtime_install_handlers (void)
101 {
102 }
103 #endif
104
105 void
mono_runtime_posix_install_handlers(void)106 mono_runtime_posix_install_handlers(void)
107 {
108 /* we still need to ignore SIGPIPE */
109 signal (SIGPIPE, SIG_IGN);
110 }
111
112 void
mono_runtime_shutdown_handlers(void)113 mono_runtime_shutdown_handlers (void)
114 {
115 }
116
117 void
mono_runtime_cleanup_handlers(void)118 mono_runtime_cleanup_handlers (void)
119 {
120 }
121
122 #else
123
124 static GHashTable *mono_saved_signal_handlers = NULL;
125
126 static struct sigaction *
get_saved_signal_handler(int signo,gboolean remove)127 get_saved_signal_handler (int signo, gboolean remove)
128 {
129 if (mono_saved_signal_handlers) {
130 /* The hash is only modified during startup, so no need for locking */
131 struct sigaction *handler = g_hash_table_lookup (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
132 if (remove && handler)
133 g_hash_table_remove (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
134 return handler;
135 }
136 return NULL;
137 }
138
139 static void
save_old_signal_handler(int signo,struct sigaction * old_action)140 save_old_signal_handler (int signo, struct sigaction *old_action)
141 {
142 struct sigaction *handler_to_save = (struct sigaction *)g_malloc (sizeof (struct sigaction));
143
144 mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_CONFIG,
145 "Saving old signal handler for signal %d.", signo);
146
147 if (! (old_action->sa_flags & SA_SIGINFO)) {
148 handler_to_save->sa_handler = old_action->sa_handler;
149 } else {
150 #ifdef MONO_ARCH_USE_SIGACTION
151 handler_to_save->sa_sigaction = old_action->sa_sigaction;
152 #endif /* MONO_ARCH_USE_SIGACTION */
153 }
154 handler_to_save->sa_mask = old_action->sa_mask;
155 handler_to_save->sa_flags = old_action->sa_flags;
156
157 if (!mono_saved_signal_handlers)
158 mono_saved_signal_handlers = g_hash_table_new_full (NULL, NULL, NULL, g_free);
159 g_hash_table_insert (mono_saved_signal_handlers, GINT_TO_POINTER (signo), handler_to_save);
160 }
161
162 static void
free_saved_signal_handlers(void)163 free_saved_signal_handlers (void)
164 {
165 if (mono_saved_signal_handlers) {
166 g_hash_table_destroy (mono_saved_signal_handlers);
167 mono_saved_signal_handlers = NULL;
168 }
169 }
170
171 /*
172 * mono_chain_signal:
173 *
174 * Call the original signal handler for the signal given by the arguments, which
175 * should be the same as for a signal handler. Returns TRUE if the original handler
176 * was called, false otherwise.
177 */
178 gboolean
MONO_SIG_HANDLER_SIGNATURE(mono_chain_signal)179 MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
180 {
181 int signal = MONO_SIG_HANDLER_GET_SIGNO ();
182 struct sigaction *saved_handler = (struct sigaction *)get_saved_signal_handler (signal, FALSE);
183
184 if (saved_handler && saved_handler->sa_handler) {
185 if (!(saved_handler->sa_flags & SA_SIGINFO)) {
186 saved_handler->sa_handler (signal);
187 } else {
188 #ifdef MONO_ARCH_USE_SIGACTION
189 saved_handler->sa_sigaction (MONO_SIG_HANDLER_PARAMS);
190 #endif /* MONO_ARCH_USE_SIGACTION */
191 }
192 return TRUE;
193 }
194 return FALSE;
195 }
196
MONO_SIG_HANDLER_FUNC(static,sigabrt_signal_handler)197 MONO_SIG_HANDLER_FUNC (static, sigabrt_signal_handler)
198 {
199 MonoJitInfo *ji = NULL;
200 MONO_SIG_HANDLER_INFO_TYPE *info = MONO_SIG_HANDLER_GET_INFO ();
201 MONO_SIG_HANDLER_GET_CONTEXT;
202
203 if (mono_thread_internal_current ())
204 ji = mono_jit_info_table_find_internal (mono_domain_get (), (char *)mono_arch_ip_from_context (ctx), TRUE, TRUE);
205 if (!ji) {
206 if (mono_chain_signal (MONO_SIG_HANDLER_PARAMS))
207 return;
208 mono_handle_native_crash ("SIGABRT", ctx, info);
209 }
210 }
211
212 #if (defined (USE_POSIX_BACKEND) && defined (SIGRTMIN)) || defined (SIGPROF)
213 #define HAVE_PROFILER_SIGNAL
214 #endif
215
216 #ifdef HAVE_PROFILER_SIGNAL
217
218 static MonoNativeThreadId sampling_thread;
219
220 static gint32 profiler_signals_sent;
221 static gint32 profiler_signals_received;
222 static gint32 profiler_signals_accepted;
223 static gint32 profiler_interrupt_signals_received;
224
MONO_SIG_HANDLER_FUNC(static,profiler_signal_handler)225 MONO_SIG_HANDLER_FUNC (static, profiler_signal_handler)
226 {
227 int old_errno = errno;
228
229 MONO_SIG_HANDLER_GET_CONTEXT;
230
231 /* See the comment in mono_runtime_shutdown_stat_profiler (). */
232 if (mono_native_thread_id_get () == sampling_thread) {
233 mono_atomic_inc_i32 (&profiler_interrupt_signals_received);
234 return;
235 }
236
237 mono_atomic_inc_i32 (&profiler_signals_received);
238
239 // Did a non-attached or detaching thread get the signal?
240 if (mono_thread_info_get_small_id () == -1 ||
241 !mono_domain_get () ||
242 !mono_tls_get_jit_tls ()) {
243 errno = old_errno;
244 return;
245 }
246
247 // See the comment in sampling_thread_func ().
248 mono_atomic_store_i32 (&mono_thread_info_current ()->profiler_signal_ack, 1);
249
250 mono_atomic_inc_i32 (&profiler_signals_accepted);
251
252 int hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
253
254 mono_thread_info_set_is_async_context (TRUE);
255
256 MONO_PROFILER_RAISE (sample_hit, (mono_arch_ip_from_context (ctx), ctx));
257
258 mono_thread_info_set_is_async_context (FALSE);
259
260 mono_hazard_pointer_restore_for_signal_handler (hp_save_index);
261
262 errno = old_errno;
263
264 mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
265 }
266
267 #endif
268
MONO_SIG_HANDLER_FUNC(static,sigquit_signal_handler)269 MONO_SIG_HANDLER_FUNC (static, sigquit_signal_handler)
270 {
271 gboolean res;
272
273 /* We use this signal to start the attach agent too */
274 res = mono_attach_start ();
275 if (res)
276 return;
277
278 mono_threads_request_thread_dump ();
279
280 mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
281 }
282
MONO_SIG_HANDLER_FUNC(static,sigusr2_signal_handler)283 MONO_SIG_HANDLER_FUNC (static, sigusr2_signal_handler)
284 {
285 gboolean enabled = mono_trace_is_enabled ();
286
287 mono_trace_enable (!enabled);
288
289 mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
290 }
291
292 static void
add_signal_handler(int signo,gpointer handler,int flags)293 add_signal_handler (int signo, gpointer handler, int flags)
294 {
295 struct sigaction sa;
296 struct sigaction previous_sa;
297
298 #ifdef MONO_ARCH_USE_SIGACTION
299 sa.sa_sigaction = (void (*)(int, siginfo_t *, void *))handler;
300 sigemptyset (&sa.sa_mask);
301 sa.sa_flags = SA_SIGINFO | flags;
302 #ifdef MONO_ARCH_SIGSEGV_ON_ALTSTACK
303
304 /*Apple likes to deliver SIGBUS for *0 */
305 #ifdef HOST_DARWIN
306 if (signo == SIGSEGV || signo == SIGBUS) {
307 #else
308 if (signo == SIGSEGV) {
309 #endif
310 sa.sa_flags |= SA_ONSTACK;
311
312 /*
313 * libgc will crash when trying to do stack marking for threads which are on
314 * an altstack, so delay the suspend signal after the signal handler has
315 * executed.
316 */
317 if (mono_gc_get_suspend_signal () != -1)
318 sigaddset (&sa.sa_mask, mono_gc_get_suspend_signal ());
319 }
320 #endif
321 if (signo == SIGSEGV) {
322 /*
323 * Delay abort signals while handling SIGSEGVs since they could go unnoticed.
324 */
325 sigset_t block_mask;
326
327 sigemptyset (&block_mask);
328 }
329 #else
330 sa.sa_handler = handler;
331 sigemptyset (&sa.sa_mask);
332 sa.sa_flags = flags;
333 #endif
334 g_assert (sigaction (signo, &sa, &previous_sa) != -1);
335
336 /* if there was already a handler in place for this signal, store it */
337 if (! (previous_sa.sa_flags & SA_SIGINFO) &&
338 (SIG_DFL == previous_sa.sa_handler)) {
339 /* it there is no sa_sigaction function and the sa_handler is default, we can safely ignore this */
340 } else {
341 if (mono_do_signal_chaining)
342 save_old_signal_handler (signo, &previous_sa);
343 }
344 }
345
346 static void
347 remove_signal_handler (int signo)
348 {
349 struct sigaction sa;
350 struct sigaction *saved_action = get_saved_signal_handler (signo, TRUE);
351
352 if (!saved_action) {
353 sa.sa_handler = SIG_DFL;
354 sigemptyset (&sa.sa_mask);
355 sa.sa_flags = 0;
356
357 sigaction (signo, &sa, NULL);
358 } else {
359 g_assert (sigaction (signo, saved_action, NULL) != -1);
360 }
361 }
362
363 void
364 mono_runtime_posix_install_handlers (void)
365 {
366
367 sigset_t signal_set;
368
369 if (mini_get_debug_options ()->handle_sigint)
370 add_signal_handler (SIGINT, mono_sigint_signal_handler, SA_RESTART);
371
372 add_signal_handler (SIGFPE, mono_sigfpe_signal_handler, 0);
373 add_signal_handler (SIGQUIT, sigquit_signal_handler, SA_RESTART);
374 add_signal_handler (SIGILL, mono_sigill_signal_handler, 0);
375 add_signal_handler (SIGBUS, mono_sigsegv_signal_handler, 0);
376 if (mono_jit_trace_calls != NULL)
377 add_signal_handler (SIGUSR2, sigusr2_signal_handler, SA_RESTART);
378
379 /* it seems to have become a common bug for some programs that run as parents
380 * of many processes to block signal delivery for real time signals.
381 * We try to detect and work around their breakage here.
382 */
383 sigemptyset (&signal_set);
384 if (mono_gc_get_suspend_signal () != -1)
385 sigaddset (&signal_set, mono_gc_get_suspend_signal ());
386 if (mono_gc_get_restart_signal () != -1)
387 sigaddset (&signal_set, mono_gc_get_restart_signal ());
388 sigaddset (&signal_set, SIGCHLD);
389 sigprocmask (SIG_UNBLOCK, &signal_set, NULL);
390
391 signal (SIGPIPE, SIG_IGN);
392
393 add_signal_handler (SIGABRT, sigabrt_signal_handler, 0);
394
395 /* catch SIGSEGV */
396 add_signal_handler (SIGSEGV, mono_sigsegv_signal_handler, 0);
397 }
398
399 #ifndef HOST_DARWIN
400 void
401 mono_runtime_install_handlers (void)
402 {
403 mono_runtime_posix_install_handlers ();
404 }
405 #endif
406
407 void
408 mono_runtime_cleanup_handlers (void)
409 {
410 if (mini_get_debug_options ()->handle_sigint)
411 remove_signal_handler (SIGINT);
412
413 remove_signal_handler (SIGFPE);
414 remove_signal_handler (SIGQUIT);
415 remove_signal_handler (SIGILL);
416 remove_signal_handler (SIGBUS);
417 if (mono_jit_trace_calls != NULL)
418 remove_signal_handler (SIGUSR2);
419
420 remove_signal_handler (SIGABRT);
421
422 remove_signal_handler (SIGSEGV);
423
424 free_saved_signal_handlers ();
425 }
426
427 #ifdef HAVE_PROFILER_SIGNAL
428
429 static volatile gint32 sampling_thread_running;
430
431 #ifdef HOST_DARWIN
432
433 static clock_serv_t sampling_clock_service;
434
435 static void
436 clock_init (MonoProfilerSampleMode mode)
437 {
438 kern_return_t ret;
439
440 do {
441 ret = host_get_clock_service (mach_host_self (), SYSTEM_CLOCK, &sampling_clock_service);
442 } while (ret == KERN_ABORTED);
443
444 if (ret != KERN_SUCCESS)
445 g_error ("%s: host_get_clock_service () returned %d", __func__, ret);
446 }
447
448 static void
449 clock_cleanup (void)
450 {
451 kern_return_t ret;
452
453 do {
454 ret = mach_port_deallocate (mach_task_self (), sampling_clock_service);
455 } while (ret == KERN_ABORTED);
456
457 if (ret != KERN_SUCCESS)
458 g_error ("%s: mach_port_deallocate () returned %d", __func__, ret);
459 }
460
461 static guint64
462 clock_get_time_ns (void)
463 {
464 kern_return_t ret;
465 mach_timespec_t mach_ts;
466
467 do {
468 ret = clock_get_time (sampling_clock_service, &mach_ts);
469 } while (ret == KERN_ABORTED);
470
471 if (ret != KERN_SUCCESS)
472 g_error ("%s: clock_get_time () returned %d", __func__, ret);
473
474 return ((guint64) mach_ts.tv_sec * 1000000000) + (guint64) mach_ts.tv_nsec;
475 }
476
477 static void
478 clock_sleep_ns_abs (guint64 ns_abs)
479 {
480 kern_return_t ret;
481 mach_timespec_t then, remain_unused;
482
483 then.tv_sec = ns_abs / 1000000000;
484 then.tv_nsec = ns_abs % 1000000000;
485
486 do {
487 ret = clock_sleep (sampling_clock_service, TIME_ABSOLUTE, then, &remain_unused);
488
489 if (ret != KERN_SUCCESS && ret != KERN_ABORTED)
490 g_error ("%s: clock_sleep () returned %d", __func__, ret);
491 } while (ret == KERN_ABORTED && mono_atomic_load_i32 (&sampling_thread_running));
492 }
493
494 #else
495
496 clockid_t sampling_posix_clock;
497
498 static void
499 clock_init (MonoProfilerSampleMode mode)
500 {
501 switch (mode) {
502 case MONO_PROFILER_SAMPLE_MODE_PROCESS: {
503 /*
504 * If we don't have clock_nanosleep (), measuring the process time
505 * makes very little sense as we can only use nanosleep () to sleep on
506 * real time.
507 */
508 #ifdef HAVE_CLOCK_NANOSLEEP
509 struct timespec ts = { 0 };
510
511 /*
512 * Some systems (e.g. Windows Subsystem for Linux) declare the
513 * CLOCK_PROCESS_CPUTIME_ID clock but don't actually support it. For
514 * those systems, we fall back to CLOCK_MONOTONIC if we get EINVAL.
515 */
516 if (clock_nanosleep (CLOCK_PROCESS_CPUTIME_ID, TIMER_ABSTIME, &ts, NULL) != EINVAL) {
517 sampling_posix_clock = CLOCK_PROCESS_CPUTIME_ID;
518 break;
519 }
520 #endif
521
522 // fallthrough
523 }
524 case MONO_PROFILER_SAMPLE_MODE_REAL: sampling_posix_clock = CLOCK_MONOTONIC; break;
525 default: g_assert_not_reached (); break;
526 }
527 }
528
529 static void
530 clock_cleanup (void)
531 {
532 }
533
534 static guint64
535 clock_get_time_ns (void)
536 {
537 struct timespec ts;
538
539 if (clock_gettime (sampling_posix_clock, &ts) == -1)
540 g_error ("%s: clock_gettime () returned -1, errno = %d", __func__, errno);
541
542 return ((guint64) ts.tv_sec * 1000000000) + (guint64) ts.tv_nsec;
543 }
544
545 static void
546 clock_sleep_ns_abs (guint64 ns_abs)
547 {
548 #ifdef HAVE_CLOCK_NANOSLEEP
549 int ret;
550 struct timespec then;
551
552 then.tv_sec = ns_abs / 1000000000;
553 then.tv_nsec = ns_abs % 1000000000;
554
555 do {
556 ret = clock_nanosleep (sampling_posix_clock, TIMER_ABSTIME, &then, NULL);
557
558 if (ret != 0 && ret != EINTR)
559 g_error ("%s: clock_nanosleep () returned %d", __func__, ret);
560 } while (ret == EINTR && mono_atomic_load_i32 (&sampling_thread_running));
561 #else
562 int ret;
563 gint64 diff;
564 struct timespec req;
565
566 /*
567 * What follows is a crude attempt at emulating clock_nanosleep () on OSs
568 * which don't provide it (e.g. FreeBSD).
569 *
570 * The problem with nanosleep () is that if it is interrupted by a signal,
571 * time will drift as a result of having to restart the call after the
572 * signal handler has finished. For this reason, we avoid using the rem
573 * argument of nanosleep (). Instead, before every nanosleep () call, we
574 * check if enough time has passed to satisfy the sleep request. If yes, we
575 * simply return. If not, we calculate the difference and do another sleep.
576 *
577 * This should reduce the amount of drift that happens because we account
578 * for the time spent executing the signal handler, which nanosleep () is
579 * not guaranteed to do for the rem argument.
580 *
581 * The downside to this approach is that it is slightly expensive: We have
582 * to make an extra system call to retrieve the current time whenever we're
583 * going to restart a nanosleep () call. This is unlikely to be a problem
584 * in practice since the sampling thread won't be receiving many signals in
585 * the first place (it's a tools thread, so no STW), and because typical
586 * sleep periods for the thread are many orders of magnitude bigger than
587 * the time it takes to actually perform that system call (just a few
588 * nanoseconds).
589 */
590 do {
591 diff = (gint64) ns_abs - (gint64) clock_get_time_ns ();
592
593 if (diff <= 0)
594 break;
595
596 req.tv_sec = diff / 1000000000;
597 req.tv_nsec = diff % 1000000000;
598
599 if ((ret = nanosleep (&req, NULL)) == -1 && errno != EINTR)
600 g_error ("%s: nanosleep () returned -1, errno = %d", __func__, errno);
601 } while (ret == -1 && mono_atomic_load_i32 (&sampling_thread_running));
602 #endif
603 }
604
605 #endif
606
607 static int profiler_signal;
608 static volatile gint32 sampling_thread_exiting;
609
610 static mono_native_thread_return_t
611 sampling_thread_func (void *data)
612 {
613 mono_threads_attach_tools_thread ();
614 mono_native_thread_set_name (mono_native_thread_id_get (), "Profiler sampler");
615
616 int old_policy;
617 struct sched_param old_sched;
618 pthread_getschedparam (pthread_self (), &old_policy, &old_sched);
619
620 /*
621 * Attempt to switch the thread to real time scheduling. This will not
622 * necessarily work on all OSs; for example, most Linux systems will give
623 * us EPERM here unless configured to allow this.
624 *
625 * TODO: This does not work on Mac (and maybe some other OSs). On Mac, we
626 * have to use the Mach thread policy routines to switch to real-time
627 * scheduling. This is quite tricky as we need to specify how often we'll
628 * be doing work (easy), the normal processing time needed (also easy),
629 * and the maximum amount of processing time needed (hard). This is
630 * further complicated by the fact that if we misbehave and take too long
631 * to do our work, the kernel may knock us back down to the normal thread
632 * scheduling policy without telling us.
633 */
634 struct sched_param sched = { .sched_priority = sched_get_priority_max (SCHED_FIFO) };
635 pthread_setschedparam (pthread_self (), SCHED_FIFO, &sched);
636
637 MonoProfilerSampleMode mode;
638
639 init:
640 mono_profiler_get_sample_mode (NULL, &mode, NULL);
641
642 if (mode == MONO_PROFILER_SAMPLE_MODE_NONE) {
643 mono_profiler_sampling_thread_wait ();
644
645 if (!mono_atomic_load_i32 (&sampling_thread_running))
646 goto done;
647
648 goto init;
649 }
650
651 clock_init (mode);
652
653 for (guint64 sleep = clock_get_time_ns (); mono_atomic_load_i32 (&sampling_thread_running); clock_sleep_ns_abs (sleep)) {
654 uint32_t freq;
655 MonoProfilerSampleMode new_mode;
656
657 mono_profiler_get_sample_mode (NULL, &new_mode, &freq);
658
659 if (new_mode != mode) {
660 clock_cleanup ();
661 goto init;
662 }
663
664 sleep += 1000000000 / freq;
665
666 FOREACH_THREAD_SAFE (info) {
667 /* info should never be this thread as we're a tools thread. */
668 g_assert (mono_thread_info_get_tid (info) != mono_native_thread_id_get ());
669
670 /*
671 * Require an ack for the last sampling signal sent to the thread
672 * so that we don't overflow the signal queue, leading to all sorts
673 * of problems (e.g. GC STW failing).
674 */
675 if (profiler_signal != SIGPROF && !mono_atomic_cas_i32 (&info->profiler_signal_ack, 0, 1))
676 continue;
677
678 mono_threads_pthread_kill (info, profiler_signal);
679 mono_atomic_inc_i32 (&profiler_signals_sent);
680 } FOREACH_THREAD_SAFE_END
681 }
682
683 clock_cleanup ();
684
685 done:
686 mono_atomic_store_i32 (&sampling_thread_exiting, 1);
687
688 pthread_setschedparam (pthread_self (), old_policy, &old_sched);
689
690 mono_thread_info_detach ();
691
692 return NULL;
693 }
694
695 void
696 mono_runtime_shutdown_stat_profiler (void)
697 {
698 mono_atomic_store_i32 (&sampling_thread_running, 0);
699
700 mono_profiler_sampling_thread_post ();
701
702 #ifndef HOST_DARWIN
703 /*
704 * There is a slight problem when we're using CLOCK_PROCESS_CPUTIME_ID: If
705 * we're shutting down and there's largely no activity in the process other
706 * than waiting for the sampler thread to shut down, it can take upwards of
707 * 20 seconds (depending on a lot of factors) for us to shut down because
708 * the sleep progresses very slowly as a result of the low CPU activity.
709 *
710 * We fix this by repeatedly sending the profiler signal to the sampler
711 * thread in order to interrupt the sleep. clock_sleep_ns_abs () will check
712 * sampling_thread_running upon an interrupt and return immediately if it's
713 * zero. profiler_signal_handler () has a special case to ignore the signal
714 * for the sampler thread.
715 */
716 MonoThreadInfo *info;
717
718 // Did it shut down already?
719 if ((info = mono_thread_info_lookup (sampling_thread))) {
720 while (!mono_atomic_load_i32 (&sampling_thread_exiting)) {
721 mono_threads_pthread_kill (info, profiler_signal);
722 mono_thread_info_usleep (10 * 1000 /* 10ms */);
723 }
724
725 // Make sure info can be freed.
726 mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
727 }
728 #endif
729
730 mono_native_thread_join (sampling_thread);
731
732 /*
733 * We can't safely remove the signal handler because we have no guarantee
734 * that all pending signals have been delivered at this point. This should
735 * not really be a problem anyway.
736 */
737 //remove_signal_handler (profiler_signal);
738 }
739
740 void
741 mono_runtime_setup_stat_profiler (void)
742 {
743 /*
744 * Use a real-time signal when possible. This gives us roughly a 99% signal
745 * delivery rate in all cases. On the other hand, using a regular signal
746 * tends to result in awful delivery rates when the application is heavily
747 * loaded.
748 *
749 * We avoid real-time signals on Android as they're super broken in certain
750 * API levels (too small sigset_t, nonsensical SIGRTMIN/SIGRTMAX values,
751 * etc).
752 *
753 * TODO: On Mac, we should explore using the Mach thread suspend/resume
754 * functions and doing the stack walk from the sampling thread. This would
755 * get us a 100% sampling rate. However, this may interfere with the GC's
756 * STW logic. Could perhaps be solved by taking the suspend lock.
757 */
758 #if defined (USE_POSIX_BACKEND) && defined (SIGRTMIN) && !defined (HOST_ANDROID)
759 /* Just take the first real-time signal we can get. */
760 profiler_signal = mono_threads_suspend_search_alternative_signal ();
761 #else
762 profiler_signal = SIGPROF;
763 #endif
764
765 add_signal_handler (profiler_signal, profiler_signal_handler, SA_RESTART);
766
767 mono_counters_register ("Sampling signals sent", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_sent);
768 mono_counters_register ("Sampling signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_received);
769 mono_counters_register ("Sampling signals accepted", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_accepted);
770 mono_counters_register ("Shutdown signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_interrupt_signals_received);
771
772 mono_atomic_store_i32 (&sampling_thread_running, 1);
773 mono_native_thread_create (&sampling_thread, sampling_thread_func, NULL);
774 }
775
776 #else
777
778 void
779 mono_runtime_shutdown_stat_profiler (void)
780 {
781 }
782
783 void
784 mono_runtime_setup_stat_profiler (void)
785 {
786 }
787
788 #endif
789
790 #endif /* defined(HOST_WATCHOS) */
791
792 static gboolean
793 native_stack_with_gdb (pid_t crashed_pid, const char **argv, FILE *commands, char* commands_filename)
794 {
795 gchar *gdb;
796
797 gdb = g_find_program_in_path ("gdb");
798 if (!gdb)
799 return FALSE;
800
801 argv [0] = gdb;
802 argv [1] = "-batch";
803 argv [2] = "-x";
804 argv [3] = commands_filename;
805 argv [4] = "-nx";
806
807 fprintf (commands, "attach %ld\n", (long) crashed_pid);
808 fprintf (commands, "info threads\n");
809 fprintf (commands, "thread apply all bt\n");
810
811 return TRUE;
812 }
813
814
815 static gboolean
816 native_stack_with_lldb (pid_t crashed_pid, const char **argv, FILE *commands, char* commands_filename)
817 {
818 gchar *lldb;
819
820 lldb = g_find_program_in_path ("lldb");
821 if (!lldb)
822 return FALSE;
823
824 argv [0] = lldb;
825 argv [1] = "--batch";
826 argv [2] = "--source";
827 argv [3] = commands_filename;
828 argv [4] = "--no-lldbinit";
829
830 fprintf (commands, "process attach --pid %ld\n", (long) crashed_pid);
831 fprintf (commands, "thread list\n");
832 fprintf (commands, "thread backtrace all\n");
833 fprintf (commands, "detach\n");
834 fprintf (commands, "quit\n");
835
836 return TRUE;
837 }
838
839 void
840 mono_gdb_render_native_backtraces (pid_t crashed_pid)
841 {
842 #ifdef HAVE_EXECV
843 const char *argv [10];
844 FILE *commands;
845 char commands_filename [] = "/tmp/mono-gdb-commands.XXXXXX";
846
847 if (mkstemp (commands_filename) == -1)
848 return;
849
850 commands = fopen (commands_filename, "w");
851 if (!commands) {
852 unlink (commands_filename);
853 return;
854 }
855
856 memset (argv, 0, sizeof (char*) * 10);
857
858 #if defined(HOST_DARWIN)
859 if (native_stack_with_lldb (crashed_pid, argv, commands, commands_filename))
860 goto exec;
861 #endif
862
863 if (native_stack_with_gdb (crashed_pid, argv, commands, commands_filename))
864 goto exec;
865
866 #if !defined(HOST_DARWIN)
867 if (native_stack_with_lldb (crashed_pid, argv, commands, commands_filename))
868 goto exec;
869 #endif
870
871 fprintf (stderr, "mono_gdb_render_native_backtraces not supported on this platform, unable to find gdb or lldb\n");
872
873 fclose (commands);
874 unlink (commands_filename);
875 return;
876
877 exec:
878 fclose (commands);
879 execv (argv [0], (char**)argv);
880
881 _exit (-1);
882 #else
883 fprintf (stderr, "mono_gdb_render_native_backtraces not supported on this platform\n");
884 #endif // HAVE_EXECV
885 }
886
887 #if !defined (__MACH__)
888
889 gboolean
890 mono_thread_state_init_from_handle (MonoThreadUnwindState *tctx, MonoThreadInfo *info, void *sigctx)
891 {
892 g_error ("Posix systems don't support mono_thread_state_init_from_handle");
893 return FALSE;
894 }
895
896 #endif
897