void
mono_threads_end_global_suspend (void)
{
g_assert (pending_suspends == 0);
THREADS_SUSPEND_DEBUG ("------ END GLOBAL OP sp %d rp %d ap %d wd %d po %d\n", suspend_posts, resume_posts,
abort_posts, waits_done, pending_ops);
mono_threads_core_end_global_suspend ();
}
void
mono_thread_info_wait_for_resume (MonoThreadInfo* info)
{
int res;
THREADS_SUSPEND_DEBUG ("**WAIT self-resume %p\n", mono_thread_info_get_tid (info));
res = mono_os_sem_wait (&info->resume_semaphore, MONO_SEM_FLAGS_NONE);
g_assert (res != -1);
}
void
mono_threads_begin_global_suspend (void)
{
g_assert (pending_suspends == 0);
THREADS_SUSPEND_DEBUG ("------ BEGIN GLOBAL OP sp %d rp %d ap %d wd %d po %d (sp + rp + ap == wd) (wd == po)\n", suspend_posts, resume_posts,
abort_posts, waits_done, pending_ops);
g_assert ((suspend_posts + resume_posts + abort_posts) == waits_done);
mono_threads_core_begin_global_suspend ();
}
gboolean
mono_threads_core_begin_async_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
{
DWORD id = mono_thread_info_get_tid (info);
HANDLE handle;
DWORD result;
gboolean res;
handle = OpenThread (THREAD_ALL_ACCESS, FALSE, id);
g_assert (handle);
result = SuspendThread (handle);
THREADS_SUSPEND_DEBUG ("SUSPEND %p -> %d\n", (void*)id, ret);
if (result == (DWORD)-1) {
CloseHandle (handle);
return FALSE;
}
/* We're in the middle of a self-suspend, resume and register */
if (!mono_threads_transition_finish_async_suspend (info)) {
mono_threads_add_to_pending_operation_set (info);
result = ResumeThread (handle);
g_assert (result == 1);
CloseHandle (handle);
THREADS_SUSPEND_DEBUG ("FAILSAFE RESUME/1 %p -> %d\n", (void*)id, 0);
//XXX interrupt_kernel doesn't make sense in this case as the target is not in a syscall
return TRUE;
}
res = mono_threads_get_runtime_callbacks ()->thread_state_init_from_handle (&info->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX], info);
THREADS_SUSPEND_DEBUG ("thread state %p -> %d\n", (void*)id, res);
if (res) {
//FIXME do we need to QueueUserAPC on this case?
if (interrupt_kernel)
QueueUserAPC ((PAPCFUNC)interrupt_apc, handle, (ULONG_PTR)NULL);
} else {
mono_threads_transition_async_suspend_compensation (info);
result = ResumeThread (handle);
g_assert (result == 1);
THREADS_SUSPEND_DEBUG ("FAILSAFE RESUME/2 %p -> %d\n", (void*)info->native_handle, 0);
}
CloseHandle (handle);
return res;
}
/*
Signal that the current thread wants to be suspended.
This function can be called without holding the suspend lock held.
To finish suspending, call mono_suspend_check.
*/
void
mono_thread_info_begin_self_suspend (void)
{
MonoThreadInfo *info = mono_thread_info_current_unchecked ();
if (!info)
return;
THREADS_SUSPEND_DEBUG ("BEGIN SELF SUSPEND OF %p\n", info);
mono_threads_transition_request_self_suspension (info);
}
gboolean
mono_threads_suspend_begin_async_suspend (MonoThreadInfo *info, gboolean interrupt_kernel)
{
kern_return_t ret;
g_assert (info);
do {
ret = thread_suspend (info->native_handle);
} while (ret == KERN_ABORTED);
THREADS_SUSPEND_DEBUG ("SUSPEND %p -> %d\n", (gpointer)(gsize)info->native_handle, ret);
if (ret != KERN_SUCCESS)
return FALSE;
if (!mono_threads_transition_finish_async_suspend (info)) {
/* We raced with self-suspend and lost. Resume the native
* thread. It is still self-suspended, waiting to be resumed.
* So suspend can continue.
*/
do {
ret = thread_resume (info->native_handle);
} while (ret == KERN_ABORTED);
g_assert (ret == KERN_SUCCESS);
info->suspend_can_continue = TRUE;
THREADS_SUSPEND_DEBUG ("\tlost race with self suspend %p\n", (gpointer)(gsize)info->native_handle);
g_assert (mono_threads_is_hybrid_suspension_enabled ());
//XXX interrupt_kernel doesn't make sense in this case as the target is not in a syscall
return TRUE;
}
info->suspend_can_continue = mono_threads_get_runtime_callbacks ()->
thread_state_init_from_handle (&info->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX], info, NULL);
THREADS_SUSPEND_DEBUG ("thread state %p -> %d\n", (gpointer)(gsize)info->native_handle, ret);
if (info->suspend_can_continue) {
if (interrupt_kernel)
thread_abort (info->native_handle);
} else {
THREADS_SUSPEND_DEBUG ("FAILSAFE RESUME/2 %p -> %d\n", (gpointer)(gsize)info->native_handle, 0);
}
return TRUE;
}
void
mono_threads_end_global_suspend (void)
{
size_t ps = pending_suspends;
if (G_UNLIKELY (ps != 0))
g_error ("pending_suspends = %d, but must be 0", ps);
THREADS_SUSPEND_DEBUG ("------ END GLOBAL OP sp %d rp %d ap %d wd %d po %d\n", suspend_posts, resume_posts,
abort_posts, waits_done, pending_ops);
g_assert ((suspend_posts + resume_posts + abort_posts) == waits_done);
mono_threads_coop_end_global_suspend ();
}
gboolean
mono_threads_suspend_begin_async_resume (MonoThreadInfo *info)
{
kern_return_t ret;
if (info->async_target) {
MonoContext tmp = info->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX].ctx;
mach_msg_type_number_t num_state, num_fpstate;
thread_state_t state, fpstate;
ucontext_t uctx;
mcontext_t mctx;
mono_threads_get_runtime_callbacks ()->setup_async_callback (&tmp, info->async_target, info->user_data);
info->user_data = NULL;
info->async_target = (void (*)(void *)) info->user_data;
state = (thread_state_t) alloca (mono_mach_arch_get_thread_state_size ());
fpstate = (thread_state_t) alloca (mono_mach_arch_get_thread_fpstate_size ());
mctx = (mcontext_t) alloca (mono_mach_arch_get_mcontext_size ());
do {
ret = mono_mach_arch_get_thread_states (info->native_handle, state, &num_state, fpstate, &num_fpstate);
} while (ret == KERN_ABORTED);
if (ret != KERN_SUCCESS)
return FALSE;
mono_mach_arch_thread_states_to_mcontext (state, fpstate, mctx);
uctx.uc_mcontext = mctx;
mono_monoctx_to_sigctx (&tmp, &uctx);
mono_mach_arch_mcontext_to_thread_states (mctx, state, fpstate);
do {
ret = mono_mach_arch_set_thread_states (info->native_handle, state, num_state, fpstate, num_fpstate);
} while (ret == KERN_ABORTED);
if (ret != KERN_SUCCESS)
return FALSE;
}
do {
ret = thread_resume (info->native_handle);
} while (ret == KERN_ABORTED);
THREADS_SUSPEND_DEBUG ("RESUME %p -> %d\n", (gpointer)(gsize)info->native_handle, ret);
return ret == KERN_SUCCESS;
}
gboolean
mono_threads_core_begin_async_resume (MonoThreadInfo *info)
{
kern_return_t ret;
if (info->async_target) {
MonoContext tmp = info->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX].ctx;
mach_msg_type_number_t num_state;
thread_state_t state;
ucontext_t uctx;
mcontext_t mctx;
mono_threads_get_runtime_callbacks ()->setup_async_callback (&tmp, info->async_target, info->user_data);
info->user_data = NULL;
info->async_target = (void (*)(void *)) info->user_data;
state = (thread_state_t) alloca (mono_mach_arch_get_thread_state_size ());
mctx = (mcontext_t) alloca (mono_mach_arch_get_mcontext_size ());
ret = mono_mach_arch_get_thread_state (info->native_handle, state, &num_state);
if (ret != KERN_SUCCESS)
return FALSE;
mono_mach_arch_thread_state_to_mcontext (state, mctx);
#ifdef TARGET_ARM64
g_assert_not_reached ();
#else
uctx.uc_mcontext = mctx;
#endif
mono_monoctx_to_sigctx (&tmp, &uctx);
mono_mach_arch_mcontext_to_thread_state (mctx, state);
ret = mono_mach_arch_set_thread_state (info->native_handle, state, num_state);
if (ret != KERN_SUCCESS)
return FALSE;
}
ret = thread_resume (info->native_handle);
THREADS_SUSPEND_DEBUG ("RESUME %p -> %d\n", (void*)info->native_handle, ret);
return ret == KERN_SUCCESS;
}
int
mono_threads_pthread_kill (MonoThreadInfo *info, int signum)
{
THREADS_SUSPEND_DEBUG ("sending signal %d to %p[%p]\n", signum, info, mono_thread_info_get_tid (info));
#ifdef USE_TKILL_ON_ANDROID
int result, old_errno = errno;
result = tkill (info->native_handle, signum);
if (result < 0) {
result = errno;
errno = old_errno;
}
return result;
#elif defined(__native_client__)
/* Workaround pthread_kill abort() in NaCl glibc. */
return 0;
#else
return pthread_kill (mono_thread_info_get_tid (info), signum);
#endif
}
/*
WARNING:
If we are trying to suspend a target that is on a critical region
and running a syscall we risk looping forever if @interrupt_kernel is FALSE.
So, be VERY carefull in calling this with @interrupt_kernel == FALSE.
Info is not put on a hazard pointer as a suspended thread cannot exit and be freed.
This function MUST be matched with mono_thread_info_finish_suspend or mono_thread_info_finish_suspend_and_resume
*/
MonoThreadInfo*
mono_thread_info_safe_suspend_sync (MonoNativeThreadId id, gboolean interrupt_kernel)
{
MonoThreadInfo *info = NULL;
THREADS_SUSPEND_DEBUG ("SUSPENDING tid %p\n", (void*)id);
/*FIXME: unify this with self-suspend*/
g_assert (id != mono_native_thread_id_get ());
mono_thread_info_suspend_lock ();
mono_threads_begin_global_suspend ();
info = suspend_sync_nolock (id, interrupt_kernel);
/* XXX this clears HP 1, so we restated it again */
// mono_atomic_store_release (&mono_thread_info_current ()->inside_critical_region, TRUE);
mono_threads_end_global_suspend ();
mono_thread_info_suspend_unlock ();
return info;
}
static MonoThreadInfo*
suspend_sync_nolock (MonoNativeThreadId id, gboolean interrupt_kernel)
{
MonoThreadInfo *info = NULL;
int sleep_duration = 0;
for (;;) {
const char *suspend_error = "Unknown error";
if (!(info = mono_thread_info_suspend_sync (id, interrupt_kernel, &suspend_error))) {
mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
return NULL;
}
/*WARNING: We now are in interrupt context until we resume the thread. */
if (!is_thread_in_critical_region (info))
break;
if (!mono_thread_info_core_resume (info)) {
mono_hazard_pointer_clear (mono_hazard_pointer_get (), 1);
return NULL;
}
THREADS_SUSPEND_DEBUG ("RESTARTED thread tid %p\n", (void*)id);
/* Wait for the pending resume to finish */
mono_threads_wait_pending_operations ();
if (!sleep_duration) {
#ifdef HOST_WIN32
SwitchToThread ();
#else
sched_yield ();
#endif
}
else {
g_usleep (sleep_duration);
}
sleep_duration += 10;
}
return info;
}
void
mono_thread_info_safe_suspend_and_run (MonoNativeThreadId id, gboolean interrupt_kernel, MonoSuspendThreadCallback callback, gpointer user_data)
{
int result;
MonoThreadInfo *info = NULL;
MonoThreadHazardPointers *hp = mono_hazard_pointer_get ();
THREADS_SUSPEND_DEBUG ("SUSPENDING tid %p\n", (void*)id);
/*FIXME: unify this with self-suspend*/
g_assert (id != mono_native_thread_id_get ());
/* This can block during stw */
mono_thread_info_suspend_lock ();
mono_threads_begin_global_suspend ();
info = suspend_sync_nolock (id, interrupt_kernel);
if (!info)
goto done;
switch (result = callback (info, user_data)) {
case MonoResumeThread:
mono_hazard_pointer_set (hp, 1, info);
mono_thread_info_core_resume (info);
mono_threads_wait_pending_operations ();
break;
case KeepSuspended:
g_assert (!mono_threads_is_coop_enabled ());
break;
default:
g_error ("Invalid suspend_and_run callback return value %d", result);
}
done:
mono_hazard_pointer_clear (hp, 1);
mono_threads_end_global_suspend ();
mono_thread_info_suspend_unlock ();
}
void
mono_threads_exit_gc_safe_region_unbalanced (gpointer cookie, gpointer *stackdata)
{
MonoThreadInfo *info;
if (!mono_threads_is_coop_enabled ())
return;
info = (MonoThreadInfo *)cookie;
check_info (info, "exit", "safe");
switch (mono_threads_transition_done_blocking (info)) {
case DoneBlockingOk:
info->thread_saved_state [SELF_SUSPEND_STATE_INDEX].valid = FALSE;
break;
case DoneBlockingWait:
THREADS_SUSPEND_DEBUG ("state polling done, notifying of resume\n");
mono_thread_info_wait_for_resume (info);
break;
default:
g_error ("Unknown thread state");
}
}
static void
suspend_signal_handler (int _dummy, siginfo_t *info, void *context)
{
int old_errno = errno;
int hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
MonoThreadInfo *current = mono_thread_info_current ();
THREADS_SUSPEND_DEBUG ("SIGNAL HANDLER FOR %p [%p]\n", mono_thread_info_get_tid (current), (void*)current->native_handle);
if (current->syscall_break_signal) {
current->syscall_break_signal = FALSE;
THREADS_SUSPEND_DEBUG ("\tsyscall break for %p\n", mono_thread_info_get_tid (current));
mono_threads_notify_initiator_of_abort (current);
goto done;
}
/* Have we raced with self suspend? */
if (!mono_threads_transition_finish_async_suspend (current)) {
current->suspend_can_continue = TRUE;
THREADS_SUSPEND_DEBUG ("\tlost race with self suspend %p\n", mono_thread_info_get_tid (current));
goto done;
}
/*
* If the thread is starting, then thread_state_init_from_sigctx returns FALSE,
* as the thread might have been attached without the domain or lmf having been
* initialized yet.
*
* One way to fix that is to keep the thread suspended (wait for the restart
* signal), and make sgen aware that even if a thread might be suspended, there
* would be cases where you cannot scan its stack/registers. That would in fact
* consist in removing the async suspend compensation, and treat the case directly
* in sgen. That's also how it was done in the sgen specific suspend code.
*/
/* thread_state_init_from_sigctx return FALSE if the current thread is starting or detaching and suspend can't continue. */
current->suspend_can_continue = mono_threads_get_runtime_callbacks ()->thread_state_init_from_sigctx (¤t->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX], context);
if (!current->suspend_can_continue)
THREADS_SUSPEND_DEBUG ("\tThread is starting or detaching, failed to capture state %p\n", mono_thread_info_get_tid (current));
/*
Block the restart signal.
We need to block the restart signal while posting to the suspend_ack semaphore or we race to sigsuspend,
which might miss the signal and get stuck.
*/
pthread_sigmask (SIG_BLOCK, &suspend_ack_signal_mask, NULL);
/* We're done suspending */
mono_threads_notify_initiator_of_suspend (current);
do {
current->signal = 0;
sigsuspend (&suspend_signal_mask);
} while (current->signal != restart_signal_num);
/* Unblock the restart signal. */
pthread_sigmask (SIG_UNBLOCK, &suspend_ack_signal_mask, NULL);
if (current->async_target) {
#if MONO_ARCH_HAS_MONO_CONTEXT
MonoContext tmp = current->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX].ctx;
mono_threads_get_runtime_callbacks ()->setup_async_callback (&tmp, current->async_target, current->user_data);
current->user_data = NULL;
current->async_target = NULL;
mono_monoctx_to_sigctx (&tmp, context);
#else
g_error ("The new interruption machinery requires a working mono-context");
#endif
}
/* We're done resuming */
mono_threads_notify_initiator_of_resume (current);
done:
mono_hazard_pointer_restore_for_signal_handler (hp_save_index);
errno = old_errno;
}
void
mono_thread_info_wait_for_resume (MonoThreadInfo* info)
{
THREADS_SUSPEND_DEBUG ("**WAIT self-resume %p\n", mono_thread_info_get_tid (info));
MONO_SEM_WAIT_UNITERRUPTIBLE (&info->resume_semaphore);
}
static void
resume_blocking_suspended (MonoThreadInfo* info)
{
THREADS_SUSPEND_DEBUG ("**BEGIN blocking-resume %p\n", mono_thread_info_get_tid (info));
mono_os_sem_post (&info->resume_semaphore);
}
static void
resume_self_suspended (MonoThreadInfo* info)
{
THREADS_SUSPEND_DEBUG ("**BEGIN self-resume %p\n", mono_thread_info_get_tid (info));
MONO_SEM_POST (&info->resume_semaphore);
}
static void
suspend_signal_handler (int _dummy, siginfo_t *info, void *context)
{
#if defined(__native_client__)
g_assert_not_reached ();
#else
int old_errno = errno;
int hp_save_index = mono_hazard_pointer_save_for_signal_handler ();
MonoThreadInfo *current = mono_thread_info_current ();
gboolean ret;
THREADS_SUSPEND_DEBUG ("SIGNAL HANDLER FOR %p [%p]\n", current, (void*)current->native_handle);
if (current->syscall_break_signal) {
current->syscall_break_signal = FALSE;
THREADS_SUSPEND_DEBUG ("\tsyscall break for %p\n", current);
mono_threads_notify_initiator_of_abort (current);
goto done;
}
/* Have we raced with self suspend? */
if (!mono_threads_transition_finish_async_suspend (current)) {
current->suspend_can_continue = TRUE;
THREADS_SUSPEND_DEBUG ("\tlost race with self suspend %p\n", current);
goto done;
}
ret = mono_threads_get_runtime_callbacks ()->thread_state_init_from_sigctx (¤t->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX], context);
/* thread_state_init_from_sigctx return FALSE if the current thread is detaching and suspend can't continue. */
current->suspend_can_continue = ret;
/*
Block the restart signal.
We need to block the restart signal while posting to the suspend_ack semaphore or we race to sigsuspend,
which might miss the signal and get stuck.
*/
pthread_sigmask (SIG_BLOCK, &suspend_ack_signal_mask, NULL);
/* This thread is doomed, all we can do is give up and let the suspender recover. */
if (!ret) {
THREADS_SUSPEND_DEBUG ("\tThread is dying, failed to capture state %p\n", current);
mono_threads_transition_async_suspend_compensation (current);
/* We're done suspending */
mono_threads_notify_initiator_of_suspend (current);
/* Unblock the restart signal. */
pthread_sigmask (SIG_UNBLOCK, &suspend_ack_signal_mask, NULL);
goto done;
}
/* We're done suspending */
mono_threads_notify_initiator_of_suspend (current);
do {
current->signal = 0;
sigsuspend (&suspend_signal_mask);
} while (current->signal != restart_signal_num);
/* Unblock the restart signal. */
pthread_sigmask (SIG_UNBLOCK, &suspend_ack_signal_mask, NULL);
if (current->async_target) {
#if MONO_ARCH_HAS_MONO_CONTEXT
MonoContext tmp = current->thread_saved_state [ASYNC_SUSPEND_STATE_INDEX].ctx;
mono_threads_get_runtime_callbacks ()->setup_async_callback (&tmp, current->async_target, current->user_data);
current->async_target = current->user_data = NULL;
mono_monoctx_to_sigctx (&tmp, context);
#else
g_error ("The new interruption machinery requires a working mono-context");
#endif
}
/* We're done resuming */
mono_threads_notify_initiator_of_resume (current);
done:
mono_hazard_pointer_restore_for_signal_handler (hp_save_index);
errno = old_errno;
#endif
}
