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|
/**
* \file
* POSIX signal handling support for Mono.
*
* Authors:
* Mono Team (mono-list@lists.ximian.com)
*
* Copyright 2001-2003 Ximian, Inc.
* Copyright 2003-2008 Ximian, Inc.
* Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
*
* See LICENSE for licensing information.
* Licensed under the MIT license. See LICENSE file in the project root for full license information.
*/
#include <config.h>
#include <signal.h>
#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_EXECINFO_H
#include <execinfo.h>
#endif
#include <math.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#ifdef HAVE_SYS_SYSCALL_H
#include <sys/syscall.h>
#endif
#ifdef HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#endif
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif
#include <errno.h>
#include <sched.h>
#include <mono/metadata/assembly.h>
#include <mono/metadata/loader.h>
#include <mono/metadata/tabledefs.h>
#include <mono/metadata/class.h>
#include <mono/metadata/object.h>
#include <mono/metadata/tokentype.h>
#include <mono/metadata/tabledefs.h>
#include <mono/metadata/threads.h>
#include <mono/metadata/appdomain.h>
#include <mono/metadata/debug-helpers.h>
#include <mono/metadata/profiler-private.h>
#include <mono/metadata/mono-config.h>
#include <mono/metadata/environment.h>
#include <mono/metadata/mono-debug.h>
#include <mono/metadata/gc-internals.h>
#include <mono/metadata/threads-types.h>
#include <mono/metadata/verify.h>
#include <mono/metadata/verify-internals.h>
#include <mono/metadata/mempool-internals.h>
#include <mono/metadata/attach.h>
#include <mono/utils/mono-math.h>
#include <mono/utils/mono-errno.h>
#include <mono/utils/mono-compiler.h>
#include <mono/utils/mono-counters.h>
#include <mono/utils/mono-logger-internals.h>
#include <mono/utils/mono-mmap.h>
#include <mono/utils/dtrace.h>
#include <mono/utils/mono-signal-handler.h>
#include <mono/utils/mono-threads.h>
#include <mono/utils/os-event.h>
#include <mono/utils/mono-state.h>
#include <mono/mini/debugger-state-machine.h>
#include "mini.h"
#include <string.h>
#include <ctype.h>
#include "trace.h"
#include "version.h"
#include "debugger-agent.h"
#include "mini-runtime.h"
#include "jit-icalls.h"
#ifdef HOST_DARWIN
#include <mach/mach.h>
#include <mach/mach_time.h>
#include <mach/clock.h>
#include <mono/utils/mono-merp.h>
#endif
#ifndef HOST_WIN32
#include <mono/utils/mono-threads-debug.h>
#endif
#include <fcntl.h>
#include <gmodule.h>
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include "mono/utils/mono-tls-inline.h"
#if defined(HOST_WATCHOS)
void
mono_runtime_setup_stat_profiler (void)
{
printf("WARNING: mono_runtime_setup_stat_profiler() called!\n");
}
void
mono_runtime_shutdown_stat_profiler (void)
{
}
gboolean
MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
{
return FALSE;
}
#ifndef HOST_DARWIN
void
mono_runtime_install_handlers (void)
{
}
#endif
void
mono_runtime_posix_install_handlers(void)
{
/* we still need to ignore SIGPIPE */
signal (SIGPIPE, SIG_IGN);
}
void
mono_runtime_shutdown_handlers (void)
{
}
void
mono_runtime_cleanup_handlers (void)
{
}
#else
static GHashTable *mono_saved_signal_handlers = NULL;
static struct sigaction *
get_saved_signal_handler (int signo, gboolean remove)
{
if (mono_saved_signal_handlers) {
/* The hash is only modified during startup, so no need for locking */
struct sigaction *handler = (struct sigaction*)g_hash_table_lookup (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
if (remove && handler)
g_hash_table_remove (mono_saved_signal_handlers, GINT_TO_POINTER (signo));
return handler;
}
return NULL;
}
static void
save_old_signal_handler (int signo, struct sigaction *old_action)
{
struct sigaction *handler_to_save = (struct sigaction *)g_malloc (sizeof (struct sigaction));
mono_trace (G_LOG_LEVEL_DEBUG, MONO_TRACE_CONFIG,
"Saving old signal handler for signal %d.", signo);
if (! (old_action->sa_flags & SA_SIGINFO)) {
handler_to_save->sa_handler = old_action->sa_handler;
} else {
#ifdef MONO_ARCH_USE_SIGACTION
handler_to_save->sa_sigaction = old_action->sa_sigaction;
#endif /* MONO_ARCH_USE_SIGACTION */
}
handler_to_save->sa_mask = old_action->sa_mask;
handler_to_save->sa_flags = old_action->sa_flags;
if (!mono_saved_signal_handlers)
mono_saved_signal_handlers = g_hash_table_new_full (NULL, NULL, NULL, g_free);
g_hash_table_insert (mono_saved_signal_handlers, GINT_TO_POINTER (signo), handler_to_save);
}
static void
free_saved_signal_handlers (void)
{
g_hash_table_destroy (mono_saved_signal_handlers);
mono_saved_signal_handlers = NULL;
}
/*
* mono_chain_signal:
*
* Call the original signal handler for the signal given by the arguments, which
* should be the same as for a signal handler. Returns TRUE if the original handler
* was called, false otherwise.
*/
gboolean
MONO_SIG_HANDLER_SIGNATURE (mono_chain_signal)
{
int signal = MONO_SIG_HANDLER_GET_SIGNO ();
struct sigaction *saved_handler = (struct sigaction *)get_saved_signal_handler (signal, FALSE);
if (saved_handler && saved_handler->sa_handler) {
if (!(saved_handler->sa_flags & SA_SIGINFO)) {
saved_handler->sa_handler (signal);
} else {
#ifdef MONO_ARCH_USE_SIGACTION
saved_handler->sa_sigaction (MONO_SIG_HANDLER_PARAMS);
#endif /* MONO_ARCH_USE_SIGACTION */
}
return TRUE;
}
return FALSE;
}
MONO_SIG_HANDLER_FUNC (static, sigabrt_signal_handler)
{
MonoJitInfo *ji = NULL;
MonoContext mctx;
MONO_SIG_HANDLER_INFO_TYPE *info = MONO_SIG_HANDLER_GET_INFO ();
MONO_SIG_HANDLER_GET_CONTEXT;
if (mono_thread_internal_current ())
ji = mono_jit_info_table_find_internal (mono_domain_get (), mono_arch_ip_from_context (ctx), TRUE, TRUE);
if (!ji) {
if (mono_chain_signal (MONO_SIG_HANDLER_PARAMS))
return;
mono_sigctx_to_monoctx (ctx, &mctx);
if (mono_dump_start ())
mono_handle_native_crash (mono_get_signame (info->si_signo), &mctx, info);
else
abort ();
}
}
MONO_SIG_HANDLER_FUNC (static, sigterm_signal_handler)
{
#ifndef DISABLE_CRASH_REPORTING
MONO_SIG_HANDLER_INFO_TYPE *info = MONO_SIG_HANDLER_GET_INFO ();
MONO_SIG_HANDLER_GET_CONTEXT;
// Note: this is only run from the non-controlling thread
MonoContext mctx;
gchar *output = NULL;
MonoStackHash hashes;
mono_sigctx_to_monoctx (ctx, &mctx);
// Will return when the dumping is done, so this thread can continue
// running. Returns FALSE on unrecoverable error.
if (mono_dump_start ()) {
// Process was killed from outside since crash reporting wasn't running yet.
mono_handle_native_crash (mono_get_signame (info->si_signo), &mctx, NULL);
} else {
// Crash reporting already running and we got a second SIGTERM from as part of thread-summarizing
if (!mono_threads_summarize_execute (&mctx, &output, &hashes, FALSE, NULL, 0))
g_error ("Crash reporter dumper exited due to fatal error.");
}
#endif
mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
}
#if (defined (USE_POSIX_BACKEND) && defined (SIGRTMIN)) || defined (SIGPROF)
#define HAVE_PROFILER_SIGNAL
#endif
#ifdef HAVE_PROFILER_SIGNAL
static MonoNativeThreadId sampling_thread;
static gint32 profiler_signals_sent;
static gint32 profiler_signals_received;
static gint32 profiler_signals_accepted;
static gint32 profiler_interrupt_signals_received;
MONO_SIG_HANDLER_FUNC (static, profiler_signal_handler)
{
int old_errno = errno;
MONO_SIG_HANDLER_GET_CONTEXT;
/* See the comment in mono_runtime_shutdown_stat_profiler (). */
if (mono_native_thread_id_get () == sampling_thread) {
mono_atomic_inc_i32 (&profiler_interrupt_signals_received);
return;
}
mono_atomic_inc_i32 (&profiler_signals_received);
// Did a non-attached or detaching thread get the signal?
if (mono_thread_info_get_small_id () == -1 ||
!mono_domain_get () ||
!mono_tls_get_jit_tls ()) {
mono_set_errno (old_errno);
return;
}
// See the comment in sampling_thread_func ().
mono_atomic_store_i32 (&mono_thread_info_current ()->profiler_signal_ack, 1);
mono_atomic_inc_i32 (&profiler_signals_accepted);
int hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
mono_thread_info_set_is_async_context (TRUE);
MONO_PROFILER_RAISE (sample_hit, ((const mono_byte*)mono_arch_ip_from_context (ctx), ctx));
mono_thread_info_set_is_async_context (FALSE);
mono_hazard_pointer_restore_for_signal_handler (hp_save_index);
mono_set_errno (old_errno);
mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
}
#endif
MONO_SIG_HANDLER_FUNC (static, sigquit_signal_handler)
{
gboolean res;
/* We use this signal to start the attach agent too */
res = mono_attach_start ();
if (res)
return;
mono_threads_request_thread_dump ();
mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
}
MONO_SIG_HANDLER_FUNC (static, sigusr2_signal_handler)
{
gboolean enabled = mono_trace_is_enabled ();
mono_trace_enable (!enabled);
mono_chain_signal (MONO_SIG_HANDLER_PARAMS);
}
typedef void MONO_SIG_HANDLER_SIGNATURE ((*MonoSignalHandler));
static void
add_signal_handler (int signo, MonoSignalHandler handler, int flags)
{
struct sigaction sa;
struct sigaction previous_sa;
#ifdef MONO_ARCH_USE_SIGACTION
sa.sa_sigaction = handler;
sigemptyset (&sa.sa_mask);
sa.sa_flags = SA_SIGINFO | flags;
#ifdef MONO_ARCH_SIGSEGV_ON_ALTSTACK
/*Apple likes to deliver SIGBUS for *0 */
#ifdef HOST_DARWIN
if (signo == SIGSEGV || signo == SIGBUS) {
#else
if (signo == SIGSEGV) {
#endif
sa.sa_flags |= SA_ONSTACK;
/*
* libgc will crash when trying to do stack marking for threads which are on
* an altstack, so delay the suspend signal after the signal handler has
* executed.
*/
if (mono_gc_get_suspend_signal () != -1)
sigaddset (&sa.sa_mask, mono_gc_get_suspend_signal ());
}
#endif
if (signo == SIGSEGV) {
/*
* Delay abort signals while handling SIGSEGVs since they could go unnoticed.
*/
sigset_t block_mask;
sigemptyset (&block_mask);
}
#else
sa.sa_handler = (void (*)(int))handler;
sigemptyset (&sa.sa_mask);
sa.sa_flags = flags;
#endif
g_assert (sigaction (signo, &sa, &previous_sa) != -1);
/* if there was already a handler in place for this signal, store it */
if (! (previous_sa.sa_flags & SA_SIGINFO) &&
(SIG_DFL == previous_sa.sa_handler)) {
/* it there is no sa_sigaction function and the sa_handler is default, we can safely ignore this */
} else {
if (mono_do_signal_chaining)
save_old_signal_handler (signo, &previous_sa);
}
}
static void
remove_signal_handler (int signo)
{
struct sigaction sa;
struct sigaction *saved_action = get_saved_signal_handler (signo, TRUE);
if (!saved_action) {
sa.sa_handler = SIG_DFL;
sigemptyset (&sa.sa_mask);
sa.sa_flags = 0;
sigaction (signo, &sa, NULL);
} else {
g_assert (sigaction (signo, saved_action, NULL) != -1);
}
}
void
mini_register_sigterm_handler (void)
{
#ifndef DISABLE_CRASH_REPORTING
static gboolean enabled;
if (!enabled) {
enabled = TRUE;
/* always catch SIGTERM, conditionals inside of handler */
add_signal_handler (SIGTERM, sigterm_signal_handler, 0);
}
#endif
}
void
mono_runtime_posix_install_handlers (void)
{
sigset_t signal_set;
sigemptyset (&signal_set);
mono_load_signames ();
if (mini_debug_options.handle_sigint) {
add_signal_handler (SIGINT, mono_sigint_signal_handler, SA_RESTART);
sigaddset (&signal_set, SIGINT);
}
add_signal_handler (SIGFPE, mono_sigfpe_signal_handler, 0);
sigaddset (&signal_set, SIGFPE);
add_signal_handler (SIGQUIT, sigquit_signal_handler, SA_RESTART);
sigaddset (&signal_set, SIGQUIT);
add_signal_handler (SIGILL, mono_crashing_signal_handler, 0);
sigaddset (&signal_set, SIGILL);
add_signal_handler (SIGBUS, mono_sigsegv_signal_handler, 0);
sigaddset (&signal_set, SIGBUS);
if (mono_jit_trace_calls != NULL) {
add_signal_handler (SIGUSR2, sigusr2_signal_handler, SA_RESTART);
sigaddset (&signal_set, SIGUSR2);
}
add_signal_handler (SIGSYS, mono_crashing_signal_handler, 0);
sigaddset (&signal_set, SIGSYS);
/* it seems to have become a common bug for some programs that run as parents
* of many processes to block signal delivery for real time signals.
* We try to detect and work around their breakage here.
*/
if (mono_gc_get_suspend_signal () != -1)
sigaddset (&signal_set, mono_gc_get_suspend_signal ());
if (mono_gc_get_restart_signal () != -1)
sigaddset (&signal_set, mono_gc_get_restart_signal ());
sigaddset (&signal_set, SIGCHLD);
signal (SIGPIPE, SIG_IGN);
sigaddset (&signal_set, SIGPIPE);
add_signal_handler (SIGABRT, sigabrt_signal_handler, 0);
sigaddset (&signal_set, SIGABRT);
/* catch SIGSEGV */
add_signal_handler (SIGSEGV, mono_sigsegv_signal_handler, 0);
sigaddset (&signal_set, SIGSEGV);
sigprocmask (SIG_UNBLOCK, &signal_set, NULL);
}
#ifndef HOST_DARWIN
void
mono_runtime_install_handlers (void)
{
mono_runtime_posix_install_handlers ();
}
#endif
void
mono_runtime_cleanup_handlers (void)
{
if (mini_debug_options.handle_sigint)
remove_signal_handler (SIGINT);
remove_signal_handler (SIGFPE);
remove_signal_handler (SIGQUIT);
remove_signal_handler (SIGILL);
remove_signal_handler (SIGBUS);
if (mono_jit_trace_calls != NULL)
remove_signal_handler (SIGUSR2);
remove_signal_handler (SIGSYS);
remove_signal_handler (SIGABRT);
remove_signal_handler (SIGSEGV);
free_saved_signal_handlers ();
}
#ifdef HAVE_PROFILER_SIGNAL
static volatile gint32 sampling_thread_running;
#ifdef HOST_DARWIN
static clock_serv_t sampling_clock_service;
static void
clock_init (MonoProfilerSampleMode mode)
{
kern_return_t ret;
do {
ret = host_get_clock_service (mach_host_self (), SYSTEM_CLOCK, &sampling_clock_service);
} while (ret == KERN_ABORTED);
if (ret != KERN_SUCCESS)
g_error ("%s: host_get_clock_service () returned %d", __func__, ret);
}
static void
clock_cleanup (void)
{
kern_return_t ret;
do {
ret = mach_port_deallocate (mach_task_self (), sampling_clock_service);
} while (ret == KERN_ABORTED);
if (ret != KERN_SUCCESS)
g_error ("%s: mach_port_deallocate () returned %d", __func__, ret);
}
static guint64
clock_get_time_ns (void)
{
kern_return_t ret;
mach_timespec_t mach_ts;
do {
ret = clock_get_time (sampling_clock_service, &mach_ts);
} while (ret == KERN_ABORTED);
if (ret != KERN_SUCCESS)
g_error ("%s: clock_get_time () returned %d", __func__, ret);
return ((guint64) mach_ts.tv_sec * 1000000000) + (guint64) mach_ts.tv_nsec;
}
static void
clock_sleep_ns_abs (guint64 ns_abs)
{
kern_return_t ret;
mach_timespec_t then, remain_unused;
then.tv_sec = ns_abs / 1000000000;
then.tv_nsec = ns_abs % 1000000000;
do {
ret = clock_sleep (sampling_clock_service, TIME_ABSOLUTE, then, &remain_unused);
if (ret != KERN_SUCCESS && ret != KERN_ABORTED)
g_error ("%s: clock_sleep () returned %d", __func__, ret);
} while (ret == KERN_ABORTED && mono_atomic_load_i32 (&sampling_thread_running));
}
#else
static clockid_t sampling_posix_clock;
static void
clock_init (MonoProfilerSampleMode mode)
{
switch (mode) {
case MONO_PROFILER_SAMPLE_MODE_PROCESS: {
/*
* If we don't have clock_nanosleep (), measuring the process time
* makes very little sense as we can only use nanosleep () to sleep on
* real time.
*/
#if defined(HAVE_CLOCK_NANOSLEEP) && !defined(__PASE__)
struct timespec ts = { 0 };
/*
* Some systems (e.g. Windows Subsystem for Linux) declare the
* CLOCK_PROCESS_CPUTIME_ID clock but don't actually support it. For
* those systems, we fall back to CLOCK_MONOTONIC if we get EINVAL.
*/
if (clock_nanosleep (CLOCK_PROCESS_CPUTIME_ID, TIMER_ABSTIME, &ts, NULL) != EINVAL) {
sampling_posix_clock = CLOCK_PROCESS_CPUTIME_ID;
break;
}
#endif
// fallthrough
}
case MONO_PROFILER_SAMPLE_MODE_REAL: sampling_posix_clock = CLOCK_MONOTONIC; break;
default: g_assert_not_reached (); break;
}
}
static void
clock_cleanup (void)
{
}
static guint64
clock_get_time_ns (void)
{
struct timespec ts;
if (clock_gettime (sampling_posix_clock, &ts) == -1)
g_error ("%s: clock_gettime () returned -1, errno = %d", __func__, errno);
return ((guint64) ts.tv_sec * 1000000000) + (guint64) ts.tv_nsec;
}
static void
clock_sleep_ns_abs (guint64 ns_abs)
{
#if defined(HAVE_CLOCK_NANOSLEEP) && !defined(__PASE__)
int ret;
struct timespec then;
then.tv_sec = ns_abs / 1000000000;
then.tv_nsec = ns_abs % 1000000000;
do {
ret = clock_nanosleep (sampling_posix_clock, TIMER_ABSTIME, &then, NULL);
if (ret != 0 && ret != EINTR)
g_error ("%s: clock_nanosleep () returned %d", __func__, ret);
} while (ret == EINTR && mono_atomic_load_i32 (&sampling_thread_running));
#else
int ret;
gint64 diff;
struct timespec req;
/*
* What follows is a crude attempt at emulating clock_nanosleep () on OSs
* which don't provide it (e.g. FreeBSD).
*
* The problem with nanosleep () is that if it is interrupted by a signal,
* time will drift as a result of having to restart the call after the
* signal handler has finished. For this reason, we avoid using the rem
* argument of nanosleep (). Instead, before every nanosleep () call, we
* check if enough time has passed to satisfy the sleep request. If yes, we
* simply return. If not, we calculate the difference and do another sleep.
*
* This should reduce the amount of drift that happens because we account
* for the time spent executing the signal handler, which nanosleep () is
* not guaranteed to do for the rem argument.
*
* The downside to this approach is that it is slightly expensive: We have
* to make an extra system call to retrieve the current time whenever we're
* going to restart a nanosleep () call. This is unlikely to be a problem
* in practice since the sampling thread won't be receiving many signals in
* the first place (it's a tools thread, so no STW), and because typical
* sleep periods for the thread are many orders of magnitude bigger than
* the time it takes to actually perform that system call (just a few
* nanoseconds).
*/
do {
diff = (gint64) ns_abs - (gint64) clock_get_time_ns ();
if (diff <= 0)
break;
req.tv_sec = diff / 1000000000;
req.tv_nsec = diff % 1000000000;
if ((ret = nanosleep (&req, NULL)) == -1 && errno != EINTR)
g_error ("%s: nanosleep () returned -1, errno = %d", __func__, errno);
} while (ret == -1 && mono_atomic_load_i32 (&sampling_thread_running));
#endif
}
#endif
static int profiler_signal;
static volatile gint32 sampling_thread_exiting;
static MonoOSEvent sampling_thread_exited;
static gsize
sampling_thread_func (gpointer unused)
{
MonoInternalThread *thread = mono_thread_internal_current ();
thread->flags |= MONO_THREAD_FLAG_DONT_MANAGE;
mono_thread_set_name_constant_ignore_error (thread, "Profiler Sampler", MonoSetThreadNameFlag_None);
mono_thread_info_set_flags (MONO_THREAD_INFO_FLAGS_NO_GC | MONO_THREAD_INFO_FLAGS_NO_SAMPLE);
int old_policy;
struct sched_param old_sched;
pthread_getschedparam (pthread_self (), &old_policy, &old_sched);
/*
* Attempt to switch the thread to real time scheduling. This will not
* necessarily work on all OSs; for example, most Linux systems will give
* us EPERM here unless configured to allow this.
*
* TODO: This does not work on Mac (and maybe some other OSs). On Mac, we
* have to use the Mach thread policy routines to switch to real-time
* scheduling. This is quite tricky as we need to specify how often we'll
* be doing work (easy), the normal processing time needed (also easy),
* and the maximum amount of processing time needed (hard). This is
* further complicated by the fact that if we misbehave and take too long
* to do our work, the kernel may knock us back down to the normal thread
* scheduling policy without telling us.
*/
struct sched_param sched;
memset (&sched, 0, sizeof (sched));
sched.sched_priority = sched_get_priority_max (SCHED_FIFO);
pthread_setschedparam (pthread_self (), SCHED_FIFO, &sched);
MonoProfilerSampleMode mode;
init:
mono_profiler_get_sample_mode (NULL, &mode, NULL);
if (mode == MONO_PROFILER_SAMPLE_MODE_NONE) {
mono_profiler_sampling_thread_wait ();
if (!mono_atomic_load_i32 (&sampling_thread_running))
goto done;
goto init;
}
clock_init (mode);
for (guint64 sleep = clock_get_time_ns (); mono_atomic_load_i32 (&sampling_thread_running); clock_sleep_ns_abs (sleep)) {
uint32_t freq;
MonoProfilerSampleMode new_mode;
mono_profiler_get_sample_mode (NULL, &new_mode, &freq);
if (new_mode != mode) {
clock_cleanup ();
goto init;
}
sleep += 1000000000 / freq;
FOREACH_THREAD_SAFE_EXCLUDE (info, MONO_THREAD_INFO_FLAGS_NO_SAMPLE) {
g_assert (mono_thread_info_get_tid (info) != sampling_thread);
/*
* Require an ack for the last sampling signal sent to the thread
* so that we don't overflow the signal queue, leading to all sorts
* of problems (e.g. GC STW failing).
*/
if (profiler_signal != SIGPROF && !mono_atomic_cas_i32 (&info->profiler_signal_ack, 0, 1))
continue;
mono_threads_pthread_kill (info, profiler_signal);
mono_atomic_inc_i32 (&profiler_signals_sent);
} FOREACH_THREAD_SAFE_END
}
clock_cleanup ();
done:
mono_atomic_store_i32 (&sampling_thread_exiting, 1);
pthread_setschedparam (pthread_self (), old_policy, &old_sched);
mono_thread_info_set_flags (MONO_THREAD_INFO_FLAGS_NONE);
mono_os_event_set (&sampling_thread_exited);
return 0;
}
void
mono_runtime_shutdown_stat_profiler (void)
{
mono_atomic_store_i32 (&sampling_thread_running, 0);
mono_profiler_sampling_thread_post ();
#ifndef HOST_DARWIN
/*
* There is a slight problem when we're using CLOCK_PROCESS_CPUTIME_ID: If
* we're shutting down and there's largely no activity in the process other
* than waiting for the sampler thread to shut down, it can take upwards of
* 20 seconds (depending on a lot of factors) for us to shut down because
* the sleep progresses very slowly as a result of the low CPU activity.
*
* We fix this by repeatedly sending the profiler signal to the sampler
* thread in order to interrupt the sleep. clock_sleep_ns_abs () will check
* sampling_thread_running upon an interrupt and return immediately if it's
* zero. profiler_signal_handler () has a special case to ignore the signal
* for the sampler thread.
*/
MonoThreadInfo *info;
// Did it shut down already?
if ((info = mono_thread_info_lookup (sampling_thread))) {
while (!mono_atomic_load_i32 (&sampling_thread_exiting)) {
mono_threads_pthread_kill (info, profiler_signal);
mono_thread_info_usleep (10 * 1000 /* 10ms */);
}
// Make sure info can be freed.
mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
}
#endif
mono_os_event_wait_one (&sampling_thread_exited, MONO_INFINITE_WAIT, FALSE);
mono_os_event_destroy (&sampling_thread_exited);
/*
* We can't safely remove the signal handler because we have no guarantee
* that all pending signals have been delivered at this point. This should
* not really be a problem anyway.
*/
//remove_signal_handler (profiler_signal);
}
void
mono_runtime_setup_stat_profiler (void)
{
/*
* Use a real-time signal when possible. This gives us roughly a 99% signal
* delivery rate in all cases. On the other hand, using a regular signal
* tends to result in awful delivery rates when the application is heavily
* loaded.
*
* We avoid real-time signals on Android as they're super broken in certain
* API levels (too small sigset_t, nonsensical SIGRTMIN/SIGRTMAX values,
* etc).
*
* TODO: On Mac, we should explore using the Mach thread suspend/resume
* functions and doing the stack walk from the sampling thread. This would
* get us a 100% sampling rate. However, this may interfere with the GC's
* STW logic. Could perhaps be solved by taking the suspend lock.
*/
#if defined (USE_POSIX_BACKEND) && defined (SIGRTMIN) && !defined (HOST_ANDROID)
/* Just take the first real-time signal we can get. */
profiler_signal = mono_threads_suspend_search_alternative_signal ();
#else
profiler_signal = SIGPROF;
#endif
add_signal_handler (profiler_signal, profiler_signal_handler, SA_RESTART);
mono_counters_register ("Sampling signals sent", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_sent);
mono_counters_register ("Sampling signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_received);
mono_counters_register ("Sampling signals accepted", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_signals_accepted);
mono_counters_register ("Shutdown signals received", MONO_COUNTER_UINT | MONO_COUNTER_PROFILER | MONO_COUNTER_MONOTONIC, &profiler_interrupt_signals_received);
mono_os_event_init (&sampling_thread_exited, FALSE);
mono_atomic_store_i32 (&sampling_thread_running, 1);
ERROR_DECL (error);
MonoInternalThread *thread = mono_thread_create_internal (mono_get_root_domain (), (gpointer)sampling_thread_func, NULL, MONO_THREAD_CREATE_FLAGS_NONE, error);
mono_error_assert_ok (error);
sampling_thread = MONO_UINT_TO_NATIVE_THREAD_ID (thread->tid);
}
#else
void
mono_runtime_shutdown_stat_profiler (void)
{
}
void
mono_runtime_setup_stat_profiler (void)
{
}
#endif
#endif /* defined(HOST_WATCHOS) */
#ifndef MONO_CROSS_COMPILE
static void
dump_memory_around_ip (MonoContext *mctx)
{
if (!mctx)
return;
g_async_safe_printf ("\n=================================================================\n");
g_async_safe_printf ("\tBasic Fault Address Reporting\n");
g_async_safe_printf ("=================================================================\n");
gpointer native_ip = MONO_CONTEXT_GET_IP (mctx);
if (native_ip) {
g_async_safe_printf ("Memory around native instruction pointer (%p):", native_ip);
mono_dump_mem (((guint8 *) native_ip) - 0x10, 0x40);
} else {
g_async_safe_printf ("instruction pointer is NULL, skip dumping");
}
}
static void
assert_printer_callback (void)
{
mono_dump_native_crash_info ("SIGABRT", NULL, NULL);
}
#if !defined (HOST_WIN32)
/**
* fork_crash_safe:
*
* Version of \c fork that is safe to call from an async context such as a
* signal handler even if the process crashed inside libc.
*
* Returns 0 to the child process, >0 to the parent process or <0 on error.
*/
static pid_t
fork_crash_safe (void)
{
pid_t pid;
/*
* glibc fork acquires some locks, so if the crash happened inside malloc/free,
* it will deadlock. Call the syscall directly instead.
*/
#if defined(HOST_ANDROID)
/* SYS_fork is defined to be __NR_fork which is not defined in some ndk versions */
g_assert_not_reached ();
#elif !defined(HOST_DARWIN) && defined(SYS_fork)
pid = (pid_t) syscall (SYS_fork);
#elif HAVE_FORK
pid = (pid_t) fork ();
#else
g_assert_not_reached ();
#endif
return pid;
}
#endif
static void
dump_native_stacktrace (const char *signal, MonoContext *mctx)
{
mono_memory_barrier ();
static gint32 middle_of_crash = 0x0;
gint32 double_faulted = mono_atomic_cas_i32 ((gint32 *)&middle_of_crash, 0x1, 0x0);
mono_memory_write_barrier ();
if (!double_faulted) {
g_assertion_disable_global (assert_printer_callback);
} else {
g_async_safe_printf ("\nAn error has occured in the native fault reporting. Some diagnostic information will be unavailable.\n");
#ifndef DISABLE_CRASH_REPORTING
// In case still enabled
mono_summarize_toggle_assertions (FALSE);
#endif
}
#ifdef HAVE_BACKTRACE_SYMBOLS
void *array [256];
int size = backtrace (array, 256);
g_async_safe_printf ("\n=================================================================\n");
g_async_safe_printf ("\tNative stacktrace:\n");
g_async_safe_printf ("=================================================================\n");
if (size == 0)
g_async_safe_printf ("\t (No frames) \n\n");
for (int i = 0; i < size; ++i) {
gpointer ip = array [i];
char sname [256], fname [256];
gboolean success = g_module_address ((void*)ip, fname, 256, NULL, sname, 256, NULL);
if (!success) {
g_async_safe_printf ("\t%p - Unknown\n", ip);
} else {
g_async_safe_printf ("\t%p - %s : %s\n", ip, fname, sname);
}
}
#if !defined(HOST_WIN32) && defined(HAVE_SYS_SYSCALL_H) && (defined(SYS_fork) || HAVE_FORK)
pid_t crashed_pid = getpid ();
#ifndef DISABLE_CRASH_REPORTING
gchar *output = NULL;
MonoStackHash hashes;
MonoStateMem merp_mem;
memset (&merp_mem, 0, sizeof (merp_mem));
if (!double_faulted) {
gboolean leave = FALSE;
gboolean dump_for_merp = FALSE;
#if defined(TARGET_OSX)
dump_for_merp = mono_merp_enabled ();
#endif
#ifndef DISABLE_STRUCTURED_CRASH
mini_register_sigterm_handler ();
#endif
if (!dump_for_merp) {
#ifdef DISABLE_STRUCTURED_CRASH
leave = TRUE;
#endif
}
MonoContext *passed_ctx = NULL;
if (!leave && mctx) {
passed_ctx = mctx;
}
g_async_safe_printf ("\n=================================================================\n");
g_async_safe_printf ("\tTelemetry Dumper:\n");
g_async_safe_printf ("=================================================================\n");
if (!leave) {
mono_summarize_timeline_start (signal);
mono_summarize_toggle_assertions (TRUE);
int mono_max_summary_len = 10000000;
int mono_state_tmp_file_tag = 1;
mono_state_alloc_mem (&merp_mem, mono_state_tmp_file_tag, mono_max_summary_len * sizeof (gchar));
// Returns success, so leave if !success
leave = !mono_threads_summarize (passed_ctx, &output, &hashes, FALSE, TRUE, (gchar *) merp_mem.mem, mono_max_summary_len);
}
if (!leave) {
// Wait for the other threads to clean up and exit their handlers
// We can't lock / wait indefinitely, in case one of these threads got stuck somehow
// while dumping.
g_async_safe_printf ("\nWaiting for dumping threads to resume\n");
sleep (1);
}
// We want our crash, and don't have telemetry
// So we dump to disk
if (!leave && !dump_for_merp) {
mono_summarize_timeline_phase_log (MonoSummaryCleanup);
mono_crash_dump (output, &hashes);
mono_summarize_timeline_phase_log (MonoSummaryDone);
mono_summarize_toggle_assertions (FALSE);
}
}
#endif // DISABLE_CRASH_REPORTING
pid_t pid = crashed_pid; /* init to some >0 value */
gboolean need_to_fork = !mini_debug_options.no_gdb_backtrace;
#if defined (TARGET_OSX) && !defined (DISABLE_CRASH_REPORTING)
need_to_fork |= mono_merp_enabled ();
#endif
if (need_to_fork)
pid = fork_crash_safe ();
#if defined (HAVE_PRCTL) && defined(PR_SET_PTRACER)
if (need_to_fork && pid > 0) {
// Allow gdb to attach to the process even if ptrace_scope sysctl variable is set to
// a value other than 0 (the most permissive ptrace scope). Most modern Linux
// distributions set the scope to 1 which allows attaching only to direct children of
// the current process
prctl (PR_SET_PTRACER, pid, 0, 0, 0);
}
#endif
#if defined(TARGET_OSX) && !defined(DISABLE_CRASH_REPORTING)
if (!double_faulted && mono_merp_enabled ()) {
/* FIXME: why are we running mono_merp_invoke in the forked process? */
if (pid == 0) {
if (output) {
gboolean merp_upload_success = mono_merp_invoke (crashed_pid, signal, output, &hashes);
if (!merp_upload_success) {
g_async_safe_printf("\nThe MERP upload step has failed.\n");
} else {
// Remove
g_async_safe_printf("\nThe MERP upload step has succeeded.\n");
mono_summarize_timeline_phase_log (MonoSummaryDone);
}
mono_summarize_toggle_assertions (FALSE);
} else {
g_async_safe_printf("\nMerp dump step not run, no dump created.\n");
}
}
}
#endif
if (!mini_debug_options.no_gdb_backtrace && pid == 0) {
dup2 (STDERR_FILENO, STDOUT_FILENO);
g_async_safe_printf ("\n=================================================================\n");
g_async_safe_printf("\tExternal Debugger Dump:\n");
g_async_safe_printf ("=================================================================\n");
mono_gdb_render_native_backtraces (crashed_pid);
_exit (1);
} else if (need_to_fork && pid > 0) {
int status;
waitpid (pid, &status, 0);
} else {
// If we can't fork, do as little as possible before exiting
#ifndef DISABLE_CRASH_REPORTING
output = NULL;
#endif
}
if (double_faulted) {
g_async_safe_printf("\nExiting early due to double fault.\n");
#ifndef DISABLE_CRASH_REPORTING
mono_state_free_mem (&merp_mem);
#endif
_exit (-1);
}
#ifndef DISABLE_CRASH_REPORTING
if (output) {
// We've already done our gdb dump and our telemetry steps. Before exiting,
// see if we can notify any attached debugger instances.
//
// At this point we are accepting that the below step might end in a crash
mini_get_dbg_callbacks ()->send_crash (output, &hashes, 0 /* wait # seconds */);
}
output = NULL;
mono_state_free_mem (&merp_mem);
#endif
#endif
#else
#ifdef HOST_ANDROID
/* set DUMPABLE for this process so debuggerd can attach with ptrace(2), see:
* https://android.googlesource.com/platform/bionic/+/151da681000c07da3c24cd30a3279b1ca017f452/linker/debugger.cpp#206
* this has changed on later versions of Android. Also, we don't want to
* set this on start-up as DUMPABLE has security implications. */
prctl (PR_SET_DUMPABLE, 1);
g_async_safe_printf("\nNo native Android stacktrace (see debuggerd output).\n");
#endif
#endif
}
void
mono_dump_native_crash_info (const char *signal, MonoContext *mctx, MONO_SIG_HANDLER_INFO_TYPE *info)
{
dump_native_stacktrace (signal, mctx);
dump_memory_around_ip (mctx);
}
void
mono_post_native_crash_handler (const char *signal, MonoContext *mctx, MONO_SIG_HANDLER_INFO_TYPE *info, gboolean crash_chaining)
{
if (!crash_chaining) {
/*Android abort is a fluke, it doesn't abort, it triggers another segv. */
#if defined (HOST_ANDROID)
exit (-1);
#else
abort ();
#endif
}
}
#endif /* !MONO_CROSS_COMPILE */
static gchar *gdb_path;
static gchar *lldb_path;
void
mono_init_native_crash_info (void)
{
gdb_path = g_find_program_in_path ("gdb");
lldb_path = g_find_program_in_path ("lldb");
mono_threads_summarize_init ();
}
void
mono_cleanup_native_crash_info (void)
{
g_free (gdb_path);
g_free (lldb_path);
}
static gboolean
native_stack_with_gdb (pid_t crashed_pid, const char **argv, int commands, char* commands_filename)
{
if (!gdb_path)
return FALSE;
argv [0] = gdb_path;
argv [1] = "-batch";
argv [2] = "-x";
argv [3] = commands_filename;
argv [4] = "-nx";
g_async_safe_fprintf (commands, "attach %ld\n", (long) crashed_pid);
g_async_safe_fprintf (commands, "info threads\n");
g_async_safe_fprintf (commands, "thread apply all bt\n");
if (mini_debug_options.verbose_gdb) {
for (int i = 0; i < 32; ++i) {
g_async_safe_fprintf (commands, "info registers\n");
g_async_safe_fprintf (commands, "info frame\n");
g_async_safe_fprintf (commands, "info locals\n");
g_async_safe_fprintf (commands, "up\n");
}
}
return TRUE;
}
static gboolean
native_stack_with_lldb (pid_t crashed_pid, const char **argv, int commands, char* commands_filename)
{
if (!lldb_path)
return FALSE;
argv [0] = lldb_path;
argv [1] = "--batch";
argv [2] = "--source";
argv [3] = commands_filename;
argv [4] = "--no-lldbinit";
g_async_safe_fprintf (commands, "process attach --pid %ld\n", (long) crashed_pid);
g_async_safe_fprintf (commands, "thread list\n");
g_async_safe_fprintf (commands, "thread backtrace all\n");
if (mini_debug_options.verbose_gdb) {
for (int i = 0; i < 32; ++i) {
g_async_safe_fprintf (commands, "reg read\n");
g_async_safe_fprintf (commands, "frame info\n");
g_async_safe_fprintf (commands, "frame variable\n");
g_async_safe_fprintf (commands, "up\n");
}
}
g_async_safe_fprintf (commands, "detach\n");
g_async_safe_fprintf (commands, "quit\n");
return TRUE;
}
void
mono_gdb_render_native_backtraces (pid_t crashed_pid)
{
#ifdef HAVE_EXECV
const char *argv [10];
memset (argv, 0, sizeof (char*) * 10);
char commands_filename [100];
commands_filename [0] = '\0';
g_snprintf (commands_filename, sizeof (commands_filename), "/tmp/mono-gdb-commands.%d", crashed_pid);
// Create this file, overwriting if it already exists
int commands_handle = g_open (commands_filename, O_TRUNC | O_WRONLY | O_CREAT, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH);
if (commands_handle == -1) {
g_async_safe_printf ("Could not make debugger temp file %s\n", commands_filename);
return;
}
#if defined(HOST_DARWIN)
// lldb hangs on attaching on Catalina
return;
//if (native_stack_with_lldb (crashed_pid, argv, commands_handle, commands_filename))
// goto exec;
#endif
if (native_stack_with_gdb (crashed_pid, argv, commands_handle, commands_filename))
goto exec;
#if !defined(HOST_DARWIN)
if (native_stack_with_lldb (crashed_pid, argv, commands_handle, commands_filename))
goto exec;
#endif
g_async_safe_printf ("mono_gdb_render_native_backtraces not supported on this platform, unable to find gdb or lldb\n");
close (commands_handle);
unlink (commands_filename);
return;
exec:
close (commands_handle);
execv (argv [0], (char**)argv);
_exit (-1);
#else
g_async_safe_printf ("mono_gdb_render_native_backtraces not supported on this platform\n");
#endif // HAVE_EXECV
}
#if !defined (__MACH__)
gboolean
mono_thread_state_init_from_handle (MonoThreadUnwindState *tctx, MonoThreadInfo *info, void *sigctx)
{
g_error ("Posix systems don't support mono_thread_state_init_from_handle");
return FALSE;
}
#endif
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