/*
* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/ScopeGuard.h>
#include <AK/Singleton.h>
#include <AK/StringBuilder.h>
#include <AK/TemporaryChange.h>
#include <AK/Time.h>
#include <Kernel/API/POSIX/signal_numbers.h>
#include <Kernel/Arch/PageDirectory.h>
#include <Kernel/Arch/SmapDisabler.h>
#include <Kernel/Arch/TrapFrame.h>
#include <Kernel/Debug.h>
#include <Kernel/Devices/KCOVDevice.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <Kernel/InterruptDisabler.h>
#include <Kernel/KSyms.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/Memory/ScopedAddressSpaceSwitcher.h>
#include <Kernel/Panic.h>
#include <Kernel/PerformanceEventBuffer.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Sections.h>
#include <Kernel/Thread.h>
#include <Kernel/ThreadTracer.h>
#include <Kernel/TimerQueue.h>
#include <Kernel/kstdio.h>
namespace Kernel {
static Singleton<SpinlockProtected<Thread::GlobalList, LockRank::None>> s_list;
SpinlockProtected<Thread::GlobalList, LockRank::None>& Thread::all_instances()
{
return *s_list;
}
ErrorOr<NonnullLockRefPtr<Thread>> Thread::try_create(NonnullLockRefPtr<Process> process)
{
auto kernel_stack_region = TRY(MM.allocate_kernel_region(default_kernel_stack_size, {}, Memory::Region::Access::ReadWrite, AllocationStrategy::AllocateNow));
kernel_stack_region->set_stack(true);
auto block_timer = TRY(try_make_lock_ref_counted<Timer>());
auto name = TRY(process->name().with([](auto& name) { return name->try_clone(); }));
return adopt_nonnull_lock_ref_or_enomem(new (nothrow) Thread(move(process), move(kernel_stack_region), move(block_timer), move(name)));
}
Thread::Thread(NonnullLockRefPtr<Process> process, NonnullOwnPtr<Memory::Region> kernel_stack_region, NonnullLockRefPtr<Timer> block_timer, NonnullOwnPtr<KString> name)
: m_process(move(process))
, m_kernel_stack_region(move(kernel_stack_region))
, m_name(move(name))
, m_block_timer(move(block_timer))
{
bool is_first_thread = m_process->add_thread(*this);
if (is_first_thread) {
// First thread gets TID == PID
m_tid = m_process->pid().value();
} else {
m_tid = Process::allocate_pid().value();
}
// FIXME: Handle KString allocation failure.
m_kernel_stack_region->set_name(MUST(KString::formatted("Kernel stack (thread {})", m_tid.value())));
Thread::all_instances().with([&](auto& list) {
list.append(*this);
});
if constexpr (THREAD_DEBUG) {
m_process->name().with([&](auto& process_name) {
dbgln("Created new thread {}({}:{})", process_name->view(), m_process->pid().value(), m_tid.value());
});
}
reset_fpu_state();
m_kernel_stack_base = m_kernel_stack_region->vaddr().get();
m_kernel_stack_top = m_kernel_stack_region->vaddr().offset(default_kernel_stack_size).get() & ~(FlatPtr)0x7u;
m_process->address_space().with([&](auto& space) {
m_regs.set_initial_state(m_process->is_kernel_process(), *space, m_kernel_stack_top);
});
// We need to add another reference if we could successfully create
// all the resources needed for this thread. The reason for this is that
// we don't want to delete this thread after dropping the reference,
// it may still be running or scheduled to be run.
// The finalizer is responsible for dropping this reference once this
// thread is ready to be cleaned up.
ref();
}
Thread::~Thread()
{
VERIFY(!m_process_thread_list_node.is_in_list());
// We shouldn't be queued
VERIFY(m_runnable_priority < 0);
}
Thread::BlockResult Thread::block_impl(BlockTimeout const& timeout, Blocker& blocker)
{
VERIFY(!Processor::current_in_irq());
VERIFY(this == Thread::current());
ScopedCritical critical;
SpinlockLocker scheduler_lock(g_scheduler_lock);
SpinlockLocker block_lock(m_block_lock);
// We need to hold m_block_lock so that nobody can unblock a blocker as soon
// as it is constructed and registered elsewhere
ScopeGuard finalize_guard([&] {
blocker.finalize();
});
if (!blocker.setup_blocker()) {
blocker.will_unblock_immediately_without_blocking(Blocker::UnblockImmediatelyReason::UnblockConditionAlreadyMet);
return BlockResult::NotBlocked;
}
// Relaxed semantics are fine for timeout_unblocked because we
// synchronize on the spin locks already.
Atomic<bool, AK::MemoryOrder::memory_order_relaxed> timeout_unblocked(false);
bool timer_was_added = false;
switch (state()) {
case Thread::State::Stopped:
// It's possible that we were requested to be stopped!
break;
case Thread::State::Running:
VERIFY(m_blocker == nullptr);
break;
default:
VERIFY_NOT_REACHED();
}
m_blocker = &blocker;
if (auto& block_timeout = blocker.override_timeout(timeout); !block_timeout.is_infinite()) {
// Process::kill_all_threads may be called at any time, which will mark all
// threads to die. In that case
timer_was_added = TimerQueue::the().add_timer_without_id(*m_block_timer, block_timeout.clock_id(), block_timeout.absolute_time(), [&]() {
VERIFY(!Processor::current_in_irq());
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
VERIFY(!m_block_lock.is_locked_by_current_processor());
// NOTE: this may execute on the same or any other processor!
SpinlockLocker scheduler_lock(g_scheduler_lock);
SpinlockLocker block_lock(m_block_lock);
if (m_blocker && !timeout_unblocked.exchange(true))
unblock();
});
if (!timer_was_added) {
// Timeout is already in the past
blocker.will_unblock_immediately_without_blocking(Blocker::UnblockImmediatelyReason::TimeoutInThePast);
m_blocker = nullptr;
return BlockResult::InterruptedByTimeout;
}
}
blocker.begin_blocking({});
set_state(Thread::State::Blocked);
block_lock.unlock();
scheduler_lock.unlock();
dbgln_if(THREAD_DEBUG, "Thread {} blocking on {} ({}) -->", *this, &blocker, blocker.state_string());
bool did_timeout = false;
u32 lock_count_to_restore = 0;
auto previous_locked = unlock_process_if_locked(lock_count_to_restore);
for (;;) {
// Yield to the scheduler, and wait for us to resume unblocked.
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
VERIFY(Processor::in_critical());
yield_without_releasing_big_lock();
VERIFY(Processor::in_critical());
SpinlockLocker block_lock2(m_block_lock);
if (m_blocker && !m_blocker->can_be_interrupted() && !m_should_die) {
block_lock2.unlock();
dbgln("Thread should not be unblocking, current state: {}", state_string());
set_state(Thread::State::Blocked);
continue;
}
// Prevent the timeout from unblocking this thread if it happens to
// be in the process of firing already
did_timeout |= timeout_unblocked.exchange(true);
if (m_blocker) {
// Remove ourselves...
VERIFY(m_blocker == &blocker);
m_blocker = nullptr;
}
dbgln_if(THREAD_DEBUG, "<-- Thread {} unblocked from {} ({})", *this, &blocker, blocker.state_string());
break;
}
// Notify the blocker that we are no longer blocking. It may need
// to clean up now while we're still holding m_lock
auto result = blocker.end_blocking({}, did_timeout); // calls was_unblocked internally
if (timer_was_added && !did_timeout) {
// Cancel the timer while not holding any locks. This allows
// the timer function to complete before we remove it
// (e.g. if it's on another processor)
TimerQueue::the().cancel_timer(*m_block_timer);
}
if (previous_locked != LockMode::Unlocked) {
// NOTE: This may trigger another call to Thread::block().
relock_process(previous_locked, lock_count_to_restore);
}
return result;
}
void Thread::block(Kernel::Mutex& lock, SpinlockLocker<Spinlock<LockRank::None>>& lock_lock, u32 lock_count)
{
VERIFY(!Processor::current_in_irq());
VERIFY(this == Thread::current());
ScopedCritical critical;
SpinlockLocker scheduler_lock(g_scheduler_lock);
SpinlockLocker block_lock(m_block_lock);
switch (state()) {
case Thread::State::Stopped:
// It's possible that we were requested to be stopped!
break;
case Thread::State::Running:
VERIFY(m_blocker == nullptr);
break;
default:
dbgln("Error: Attempting to block with invalid thread state - {}", state_string());
VERIFY_NOT_REACHED();
}
// If we're blocking on the big-lock we may actually be in the process
// of unblocking from another lock. If that's the case m_blocking_mutex
// is already set
auto& big_lock = process().big_lock();
VERIFY((&lock == &big_lock && m_blocking_mutex != &big_lock) || !m_blocking_mutex);
auto* previous_blocking_mutex = m_blocking_mutex;
m_blocking_mutex = &lock;
m_lock_requested_count = lock_count;
set_state(Thread::State::Blocked);
block_lock.unlock();
scheduler_lock.unlock();
lock_lock.unlock();
dbgln_if(THREAD_DEBUG, "Thread {} blocking on Mutex {}", *this, &lock);
for (;;) {
// Yield to the scheduler, and wait for us to resume unblocked.
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
VERIFY(Processor::in_critical());
if (&lock != &big_lock && big_lock.is_exclusively_locked_by_current_thread()) {
// We're locking another lock and already hold the big lock...
// We need to release the big lock
yield_and_release_relock_big_lock();
} else {
// By the time we've reached this another thread might have
// marked us as holding the big lock, so this call must not
// verify that we're not holding it.
yield_without_releasing_big_lock(VerifyLockNotHeld::No);
}
VERIFY(Processor::in_critical());
SpinlockLocker block_lock2(m_block_lock);
VERIFY(!m_blocking_mutex);
m_blocking_mutex = previous_blocking_mutex;
break;
}
lock_lock.lock();
}
u32 Thread::unblock_from_mutex(Kernel::Mutex& mutex)
{
SpinlockLocker scheduler_lock(g_scheduler_lock);
SpinlockLocker block_lock(m_block_lock);
VERIFY(!Processor::current_in_irq());
VERIFY(m_blocking_mutex == &mutex);
dbgln_if(THREAD_DEBUG, "Thread {} unblocked from Mutex {}", *this, &mutex);
auto requested_count = m_lock_requested_count;
m_blocking_mutex = nullptr;
if (Thread::current() == this) {
set_state(Thread::State::Running);
return requested_count;
}
VERIFY(m_state != Thread::State::Runnable && m_state != Thread::State::Running);
set_state(Thread::State::Runnable);
return requested_count;
}
void Thread::unblock_from_blocker(Blocker& blocker)
{
auto do_unblock = [&]() {
SpinlockLocker scheduler_lock(g_scheduler_lock);
SpinlockLocker block_lock(m_block_lock);
if (m_blocker != &blocker)
return;
if (!should_be_stopped() && !is_stopped())
unblock();
};
if (Processor::current_in_irq() != 0) {
Processor::deferred_call_queue([do_unblock = move(do_unblock), self = try_make_weak_ptr().release_value_but_fixme_should_propagate_errors()]() {
if (auto this_thread = self.strong_ref())
do_unblock();
});
} else {
do_unblock();
}
}
void Thread::unblock(u8 signal)
{
VERIFY(!Processor::current_in_irq());
VERIFY(g_scheduler_lock.is_locked_by_current_processor());
VERIFY(m_block_lock.is_locked_by_current_processor());
if (m_state != Thread::State::Blocked)
return;
if (m_blocking_mutex)
return;
VERIFY(m_blocker);
if (signal != 0) {
if (is_handling_page_fault()) {
// Don't let signals unblock threads that are blocked inside a page fault handler.
// This prevents threads from EINTR'ing the inode read in an inode page fault.
// FIXME: There's probably a better way to solve this.
return;
}
if (!m_blocker->can_be_interrupted() && !m_should_die)
return;
m_blocker->set_interrupted_by_signal(signal);
}
m_blocker = nullptr;
if (Thread::current() == this) {
set_state(Thread::State::Running);
return;
}
VERIFY(m_state != Thread::State::Runnable && m_state != Thread::State::Running);
set_state(Thread::State::Runnable);
}
void Thread::set_should_die()
{
if (m_should_die) {
dbgln("{} Should already die", *this);
return;
}
ScopedCritical critical;
// Remember that we should die instead of returning to
// the userspace.
SpinlockLocker lock(g_scheduler_lock);
m_should_die = true;
// NOTE: Even the current thread can technically be in "Stopped"
// state! This is the case when another thread sent a SIGSTOP to
// it while it was running and it calls e.g. exit() before
// the scheduler gets involved again.
if (is_stopped()) {
// If we were stopped, we need to briefly resume so that
// the kernel stacks can clean up. We won't ever return back
// to user mode, though
VERIFY(!process().is_stopped());
resume_from_stopped();
}
if (is_blocked()) {
SpinlockLocker block_lock(m_block_lock);
if (m_blocker) {
// We're blocked in the kernel.
m_blocker->set_interrupted_by_death();
unblock();
}
}
}
void Thread::die_if_needed()
{
VERIFY(Thread::current() == this);
if (!m_should_die)
return;
u32 unlock_count;
[[maybe_unused]] auto rc = unlock_process_if_locked(unlock_count);
dbgln_if(THREAD_DEBUG, "Thread {} is dying", *this);
{
SpinlockLocker lock(g_scheduler_lock);
// It's possible that we don't reach the code after this block if the
// scheduler is invoked and FinalizerTask cleans up this thread, however
// that doesn't matter because we're trying to invoke the scheduler anyway
set_state(Thread::State::Dying);
}
ScopedCritical critical;
// Flag a context switch. Because we're in a critical section,
// Scheduler::yield will actually only mark a pending context switch
// Simply leaving the critical section would not necessarily trigger
// a switch.
Scheduler::yield();
// Now leave the critical section so that we can also trigger the
// actual context switch
Processor::clear_critical();
dbgln("die_if_needed returned from clear_critical!!! in irq: {}", Processor::current_in_irq());
// We should never get here, but the scoped scheduler lock
// will be released by Scheduler::context_switch again
VERIFY_NOT_REACHED();
}
void Thread::exit(void* exit_value)
{
VERIFY(Thread::current() == this);
m_join_blocker_set.thread_did_exit(exit_value);
set_should_die();
u32 unlock_count;
[[maybe_unused]] auto rc = unlock_process_if_locked(unlock_count);
if (m_thread_specific_range.has_value()) {
process().address_space().with([&](auto& space) {
auto* region = space->find_region_from_range(m_thread_specific_range.value());
space->deallocate_region(*region);
});
}
#ifdef ENABLE_KERNEL_COVERAGE_COLLECTION
KCOVDevice::free_thread();
#endif
die_if_needed();
}
void Thread::yield_without_releasing_big_lock(VerifyLockNotHeld verify_lock_not_held)
{
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
VERIFY(verify_lock_not_held == VerifyLockNotHeld::No || !process().big_lock().is_exclusively_locked_by_current_thread());
// Disable interrupts here. This ensures we don't accidentally switch contexts twice
InterruptDisabler disable;
Scheduler::yield(); // flag a switch
u32 prev_critical = Processor::clear_critical();
// NOTE: We may be on a different CPU now!
Processor::restore_critical(prev_critical);
}
void Thread::yield_and_release_relock_big_lock()
{
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
// Disable interrupts here. This ensures we don't accidentally switch contexts twice
InterruptDisabler disable;
Scheduler::yield(); // flag a switch
u32 lock_count_to_restore = 0;
auto previous_locked = unlock_process_if_locked(lock_count_to_restore);
// NOTE: Even though we call Scheduler::yield here, unless we happen
// to be outside of a critical section, the yield will be postponed
// until leaving it in relock_process.
relock_process(previous_locked, lock_count_to_restore);
}
LockMode Thread::unlock_process_if_locked(u32& lock_count_to_restore)
{
return process().big_lock().force_unlock_exclusive_if_locked(lock_count_to_restore);
}
void Thread::relock_process(LockMode previous_locked, u32 lock_count_to_restore)
{
// Clearing the critical section may trigger the context switch
// flagged by calling Scheduler::yield above.
// We have to do it this way because we intentionally
// leave the critical section here to be able to switch contexts.
u32 prev_critical = Processor::clear_critical();
// CONTEXT SWITCH HAPPENS HERE!
// NOTE: We may be on a different CPU now!
Processor::restore_critical(prev_critical);
if (previous_locked != LockMode::Unlocked) {
// We've unblocked, relock the process if needed and carry on.
process().big_lock().restore_exclusive_lock(lock_count_to_restore);
}
}
// NOLINTNEXTLINE(readability-make-member-function-const) False positive; We call block<SleepBlocker> which is not const
auto Thread::sleep(clockid_t clock_id, Time const& duration, Time* remaining_time) -> BlockResult
{
VERIFY(state() == Thread::State::Running);
return Thread::current()->block<Thread::SleepBlocker>({}, Thread::BlockTimeout(false, &duration, nullptr, clock_id), remaining_time);
}
// NOLINTNEXTLINE(readability-make-member-function-const) False positive; We call block<SleepBlocker> which is not const
auto Thread::sleep_until(clockid_t clock_id, Time const& deadline) -> BlockResult
{
VERIFY(state() == Thread::State::Running);
return Thread::current()->block<Thread::SleepBlocker>({}, Thread::BlockTimeout(true, &deadline, nullptr, clock_id));
}
StringView Thread::state_string() const
{
switch (state()) {
case Thread::State::Invalid:
return "Invalid"sv;
case Thread::State::Runnable:
return "Runnable"sv;
case Thread::State::Running:
return "Running"sv;
case Thread::State::Dying:
return "Dying"sv;
case Thread::State::Dead:
return "Dead"sv;
case Thread::State::Stopped:
return "Stopped"sv;
case Thread::State::Blocked: {
SpinlockLocker block_lock(m_block_lock);
if (m_blocking_mutex)
return "Mutex"sv;
if (m_blocker)
return m_blocker->state_string();
VERIFY_NOT_REACHED();
}
}
PANIC("Thread::state_string(): Invalid state: {}", (int)state());
}
void Thread::finalize()
{
VERIFY(Thread::current() == g_finalizer);
VERIFY(Thread::current() != this);
#if LOCK_DEBUG
VERIFY(!m_lock.is_locked_by_current_processor());
if (lock_count() > 0) {
dbgln("Thread {} leaking {} Locks!", *this, lock_count());
SpinlockLocker list_lock(m_holding_locks_lock);
for (auto& info : m_holding_locks_list) {
auto const& location = info.lock_location;
dbgln(" - Mutex: \"{}\" @ {} locked in function \"{}\" at \"{}:{}\" with a count of: {}", info.lock->name(), info.lock, location.function_name(), location.filename(), location.line_number(), info.count);
}
VERIFY_NOT_REACHED();
}
#endif
{
SpinlockLocker lock(g_scheduler_lock);
dbgln_if(THREAD_DEBUG, "Finalizing thread {}", *this);
set_state(Thread::State::Dead);
m_join_blocker_set.thread_finalizing();
}
if (m_dump_backtrace_on_finalization) {
auto trace_or_error = backtrace();
if (!trace_or_error.is_error()) {
auto trace = trace_or_error.release_value();
dbgln("Backtrace:");
kernelputstr(trace->characters(), trace->length());
}
}
drop_thread_count();
}
void Thread::drop_thread_count()
{
bool is_last = process().remove_thread(*this);
if (is_last)
process().finalize();
}
void Thread::finalize_dying_threads()
{
VERIFY(Thread::current() == g_finalizer);
Vector<Thread*, 32> dying_threads;
{
SpinlockLocker lock(g_scheduler_lock);
for_each_in_state(Thread::State::Dying, [&](Thread& thread) {
if (!thread.is_finalizable())
return;
auto result = dying_threads.try_append(&thread);
// We ignore allocation failures above the first 32 guaranteed thread slots, and
// just flag our future-selves to finalize these threads at a later point
if (result.is_error())
g_finalizer_has_work.store(true, AK::MemoryOrder::memory_order_release);
});
}
for (auto* thread : dying_threads) {
LockRefPtr<Process> process = thread->process();
dbgln_if(PROCESS_DEBUG, "Before finalization, {} has {} refs and its process has {}",
*thread, thread->ref_count(), thread->process().ref_count());
thread->finalize();
dbgln_if(PROCESS_DEBUG, "After finalization, {} has {} refs and its process has {}",
*thread, thread->ref_count(), thread->process().ref_count());
// This thread will never execute again, drop the running reference
// NOTE: This may not necessarily drop the last reference if anything
// else is still holding onto this thread!
thread->unref();
}
}
void Thread::update_time_scheduled(u64 current_scheduler_time, bool is_kernel, bool no_longer_running)
{
if (m_last_time_scheduled.has_value()) {
u64 delta;
if (current_scheduler_time >= m_last_time_scheduled.value())
delta = current_scheduler_time - m_last_time_scheduled.value();
else
delta = m_last_time_scheduled.value() - current_scheduler_time; // the unlikely event that the clock wrapped
if (delta != 0) {
// Add it to the global total *before* updating the thread's value!
Scheduler::add_time_scheduled(delta, is_kernel);
auto& total_time = is_kernel ? m_total_time_scheduled_kernel : m_total_time_scheduled_user;
total_time.fetch_add(delta, AK::memory_order_relaxed);
}
}
if (no_longer_running)
m_last_time_scheduled = {};
else
m_last_time_scheduled = current_scheduler_time;
}
bool Thread::tick()
{
if (previous_mode() == ExecutionMode::Kernel) {
++m_process->m_ticks_in_kernel;
++m_ticks_in_kernel;
} else {
++m_process->m_ticks_in_user;
++m_ticks_in_user;
}
--m_ticks_left;
return m_ticks_left != 0;
}
void Thread::check_dispatch_pending_signal()
{
auto result = DispatchSignalResult::Continue;
{
SpinlockLocker scheduler_lock(g_scheduler_lock);
if (pending_signals_for_state() != 0) {
result = dispatch_one_pending_signal();
}
}
if (result == DispatchSignalResult::Yield) {
yield_without_releasing_big_lock();
}
}
u32 Thread::pending_signals() const
{
SpinlockLocker lock(g_scheduler_lock);
return pending_signals_for_state();
}
u32 Thread::pending_signals_for_state() const
{
VERIFY(g_scheduler_lock.is_locked_by_current_processor());
constexpr u32 stopped_signal_mask = (1 << (SIGCONT - 1)) | (1 << (SIGKILL - 1)) | (1 << (SIGTRAP - 1));
if (is_handling_page_fault())
return 0;
return m_state != State::Stopped ? m_pending_signals : m_pending_signals & stopped_signal_mask;
}
void Thread::send_signal(u8 signal, [[maybe_unused]] Process* sender)
{
VERIFY(signal < NSIG);
VERIFY(process().is_user_process());
SpinlockLocker scheduler_lock(g_scheduler_lock);
// FIXME: Figure out what to do for masked signals. Should we also ignore them here?
if (should_ignore_signal(signal)) {
dbgln_if(SIGNAL_DEBUG, "Signal {} was ignored by {}", signal, process());
return;
}
if constexpr (SIGNAL_DEBUG) {
if (sender)
dbgln("Signal: {} sent {} to {}", *sender, signal, process());
else
dbgln("Signal: Kernel send {} to {}", signal, process());
}
m_pending_signals |= 1 << (signal - 1);
m_signal_senders[signal] = sender ? sender->pid() : pid();
m_have_any_unmasked_pending_signals.store((pending_signals_for_state() & ~m_signal_mask) != 0, AK::memory_order_release);
m_signal_blocker_set.unblock_all_blockers_whose_conditions_are_met();
if (!has_unmasked_pending_signals())
return;
if (m_state == Thread::State::Stopped) {
if (pending_signals_for_state() != 0) {
dbgln_if(SIGNAL_DEBUG, "Signal: Resuming stopped {} to deliver signal {}", *this, signal);
resume_from_stopped();
}
} else {
SpinlockLocker block_lock(m_block_lock);
dbgln_if(SIGNAL_DEBUG, "Signal: Unblocking {} to deliver signal {}", *this, signal);
unblock(signal);
}
}
u32 Thread::update_signal_mask(u32 signal_mask)
{
SpinlockLocker lock(g_scheduler_lock);
auto previous_signal_mask = m_signal_mask;
m_signal_mask = signal_mask;
m_have_any_unmasked_pending_signals.store((pending_signals_for_state() & ~m_signal_mask) != 0, AK::memory_order_release);
return previous_signal_mask;
}
u32 Thread::signal_mask() const
{
SpinlockLocker lock(g_scheduler_lock);
return m_signal_mask;
}
u32 Thread::signal_mask_block(sigset_t signal_set, bool block)
{
SpinlockLocker lock(g_scheduler_lock);
auto previous_signal_mask = m_signal_mask;
if (block)
m_signal_mask |= signal_set;
else
m_signal_mask &= ~signal_set;
m_have_any_unmasked_pending_signals.store((pending_signals_for_state() & ~m_signal_mask) != 0, AK::memory_order_release);
return previous_signal_mask;
}
void Thread::reset_signals_for_exec()
{
SpinlockLocker lock(g_scheduler_lock);
// The signal mask is preserved across execve(2).
// The pending signal set is preserved across an execve(2).
m_have_any_unmasked_pending_signals.store(false, AK::memory_order_release);
m_signal_action_masks.fill({});
// A successful call to execve(2) removes any existing alternate signal stack
m_alternative_signal_stack = 0;
m_alternative_signal_stack_size = 0;
}
// Certain exceptions, such as SIGSEGV and SIGILL, put a
// thread into a state where the signal handler must be
// invoked immediately, otherwise it will continue to fault.
// This function should be used in an exception handler to
// ensure that when the thread resumes, it's executing in
// the appropriate signal handler.
void Thread::send_urgent_signal_to_self(u8 signal)
{
VERIFY(Thread::current() == this);
DispatchSignalResult result;
{
SpinlockLocker lock(g_scheduler_lock);
result = dispatch_signal(signal);
}
if (result == DispatchSignalResult::Terminate) {
Thread::current()->die_if_needed();
VERIFY_NOT_REACHED(); // dispatch_signal will request termination of the thread, so the above call should never return
}
if (result == DispatchSignalResult::Yield)
yield_and_release_relock_big_lock();
}
DispatchSignalResult Thread::dispatch_one_pending_signal()
{
VERIFY(g_scheduler_lock.is_locked_by_current_processor());
u32 signal_candidates = pending_signals_for_state() & ~m_signal_mask;
if (signal_candidates == 0)
return DispatchSignalResult::Continue;
u8 signal = 1;
for (; signal < NSIG; ++signal) {
if ((signal_candidates & (1 << (signal - 1))) != 0) {
break;
}
}
return dispatch_signal(signal);
}
DispatchSignalResult Thread::try_dispatch_one_pending_signal(u8 signal)
{
VERIFY(signal != 0);
SpinlockLocker scheduler_lock(g_scheduler_lock);
u32 signal_candidates = pending_signals_for_state() & ~m_signal_mask;
if ((signal_candidates & (1 << (signal - 1))) == 0)
return DispatchSignalResult::Continue;
return dispatch_signal(signal);
}
enum class DefaultSignalAction {
Terminate,
Ignore,
DumpCore,
Stop,
Continue,
};
static DefaultSignalAction default_signal_action(u8 signal)
{
VERIFY(signal && signal < NSIG);
switch (signal) {
case SIGHUP:
case SIGINT:
case SIGKILL:
case SIGPIPE:
case SIGALRM:
case SIGUSR1:
case SIGUSR2:
case SIGVTALRM:
case SIGSTKFLT:
case SIGIO:
case SIGPROF:
case SIGTERM:
case SIGCANCEL:
return DefaultSignalAction::Terminate;
case SIGCHLD:
case SIGURG:
case SIGWINCH:
case SIGINFO:
return DefaultSignalAction::Ignore;
case SIGQUIT:
case SIGILL:
case SIGTRAP:
case SIGABRT:
case SIGBUS:
case SIGFPE:
case SIGSEGV:
case SIGXCPU:
case SIGXFSZ:
case SIGSYS:
return DefaultSignalAction::DumpCore;
case SIGCONT:
return DefaultSignalAction::Continue;
case SIGSTOP:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
return DefaultSignalAction::Stop;
default:
VERIFY_NOT_REACHED();
}
}
bool Thread::should_ignore_signal(u8 signal) const
{
VERIFY(signal < NSIG);
auto const& action = m_process->m_signal_action_data[signal];
if (action.handler_or_sigaction.is_null())
return default_signal_action(signal) == DefaultSignalAction::Ignore;
return ((sighandler_t)action.handler_or_sigaction.get() == SIG_IGN);
}
bool Thread::has_signal_handler(u8 signal) const
{
VERIFY(signal < NSIG);
auto const& action = m_process->m_signal_action_data[signal];
return !action.handler_or_sigaction.is_null();
}
bool Thread::is_signal_masked(u8 signal) const
{
VERIFY(signal < NSIG);
return (1 << (signal - 1)) & m_signal_mask;
}
bool Thread::has_alternative_signal_stack() const
{
return m_alternative_signal_stack_size != 0;
}
bool Thread::is_in_alternative_signal_stack() const
{
auto sp = get_register_dump_from_stack().userspace_sp();
return sp >= m_alternative_signal_stack && sp < m_alternative_signal_stack + m_alternative_signal_stack_size;
}
static ErrorOr<void> push_value_on_user_stack(FlatPtr& stack, FlatPtr data)
{
stack -= sizeof(FlatPtr);
return copy_to_user((FlatPtr*)stack, &data);
}
template<typename T>
static ErrorOr<void> copy_value_on_user_stack(FlatPtr& stack, T const& data)
{
stack -= sizeof(data);
return copy_to_user((RemoveCVReference<T>*)stack, &data);
}
void Thread::resume_from_stopped()
{
VERIFY(is_stopped());
VERIFY(m_stop_state != State::Invalid);
VERIFY(g_scheduler_lock.is_locked_by_current_processor());
if (m_stop_state == Thread::State::Blocked) {
SpinlockLocker block_lock(m_block_lock);
if (m_blocker || m_blocking_mutex) {
// Hasn't been unblocked yet
set_state(Thread::State::Blocked, 0);
} else {
// Was unblocked while stopped
set_state(Thread::State::Runnable);
}
} else {
set_state(m_stop_state, 0);
}
}
DispatchSignalResult Thread::dispatch_signal(u8 signal)
{
VERIFY_INTERRUPTS_DISABLED();
VERIFY(g_scheduler_lock.is_locked_by_current_processor());
VERIFY(signal > 0 && signal <= NSIG);
VERIFY(process().is_user_process());
VERIFY(this == Thread::current());
dbgln_if(SIGNAL_DEBUG, "Dispatch signal {} to {}, state: {}", signal, *this, state_string());
if (m_state == Thread::State::Invalid || !is_initialized()) {
// Thread has barely been created, we need to wait until it is
// at least in Runnable state and is_initialized() returns true,
// which indicates that it is fully set up an we actually have
// a register state on the stack that we can modify
return DispatchSignalResult::Deferred;
}
auto& action = m_process->m_signal_action_data[signal];
auto sender_pid = m_signal_senders[signal];
auto sender = Process::from_pid_ignoring_jails(sender_pid);
if (!current_trap() && !action.handler_or_sigaction.is_null()) {
// We're trying dispatch a handled signal to a user process that was scheduled
// after a yielding/blocking kernel thread, we don't have a register capture of
// the thread, so just defer processing the signal to later.
return DispatchSignalResult::Deferred;
}
// Mark this signal as handled.
m_pending_signals &= ~(1 << (signal - 1));
m_have_any_unmasked_pending_signals.store((m_pending_signals & ~m_signal_mask) != 0, AK::memory_order_release);
auto& process = this->process();
auto* tracer = process.tracer();
if (signal == SIGSTOP || (tracer && default_signal_action(signal) == DefaultSignalAction::DumpCore)) {
dbgln_if(SIGNAL_DEBUG, "Signal {} stopping this thread", signal);
if (tracer)
tracer->set_regs(get_register_dump_from_stack());
set_state(Thread::State::Stopped, signal);
return DispatchSignalResult::Yield;
}
if (signal == SIGCONT) {
dbgln("signal: SIGCONT resuming {}", *this);
} else {
if (tracer) {
// when a thread is traced, it should be stopped whenever it receives a signal
// the tracer is notified of this by using waitpid()
// only "pending signals" from the tracer are sent to the tracee
if (!tracer->has_pending_signal(signal)) {
dbgln("signal: {} stopping {} for tracer", signal, *this);
set_state(Thread::State::Stopped, signal);
return DispatchSignalResult::Yield;
}
tracer->unset_signal(signal);
}
}
auto handler_vaddr = action.handler_or_sigaction;
if (handler_vaddr.is_null()) {
switch (default_signal_action(signal)) {
case DefaultSignalAction::Stop:
set_state(Thread::State::Stopped, signal);
return DispatchSignalResult::Yield;
case DefaultSignalAction::DumpCore:
process.set_should_generate_coredump(true);
process.for_each_thread([](auto& thread) {
thread.set_dump_backtrace_on_finalization();
});
[[fallthrough]];
case DefaultSignalAction::Terminate:
m_process->terminate_due_to_signal(signal);
return DispatchSignalResult::Terminate;
case DefaultSignalAction::Ignore:
VERIFY_NOT_REACHED();
case DefaultSignalAction::Continue:
return DispatchSignalResult::Continue;
}
VERIFY_NOT_REACHED();
}
if ((sighandler_t)handler_vaddr.as_ptr() == SIG_IGN) {
dbgln_if(SIGNAL_DEBUG, "Ignored signal {}", signal);
return DispatchSignalResult::Continue;
}
ScopedAddressSpaceSwitcher switcher(m_process);
m_currently_handled_signal = signal;
u32 old_signal_mask = m_signal_mask;
u32 new_signal_mask = m_signal_action_masks[signal].value_or(action.mask);
if ((action.flags & SA_NODEFER) == SA_NODEFER)
new_signal_mask &= ~(1 << (signal - 1));
else
new_signal_mask |= 1 << (signal - 1);
m_signal_mask |= new_signal_mask;
m_have_any_unmasked_pending_signals.store((m_pending_signals & ~m_signal_mask) != 0, AK::memory_order_release);
bool use_alternative_stack = ((action.flags & SA_ONSTACK) != 0) && has_alternative_signal_stack() && !is_in_alternative_signal_stack();
auto setup_stack = [&](RegisterState& state) -> ErrorOr<void> {
FlatPtr stack;
if (use_alternative_stack)
stack = m_alternative_signal_stack + m_alternative_signal_stack_size;
else
stack = state.userspace_sp();
dbgln_if(SIGNAL_DEBUG, "Setting up user stack to return to IP {:p}, SP {:p}", state.ip(), state.userspace_sp());
__ucontext ucontext {
.uc_link = nullptr,
.uc_sigmask = old_signal_mask,
.uc_stack = {
.ss_sp = bit_cast<void*>(stack),
.ss_flags = action.flags & SA_ONSTACK,
.ss_size = use_alternative_stack ? m_alternative_signal_stack_size : 0,
},
.uc_mcontext = {},
};
copy_kernel_registers_into_ptrace_registers(static_cast<PtraceRegisters&>(ucontext.uc_mcontext), state);
auto fill_signal_info_for_signal = [&](siginfo& signal_info) {
if (signal == SIGCHLD) {
if (!sender) {
signal_info.si_code = CLD_EXITED;
return;
}
auto const* thread = sender->thread_list().with([](auto& list) { return list.is_empty() ? nullptr : list.first(); });
if (!thread) {
signal_info.si_code = CLD_EXITED;
return;
}
switch (thread->m_state) {
case State::Dead:
if (sender->should_generate_coredump() && sender->is_dumpable()) {
signal_info.si_code = CLD_DUMPED;
signal_info.si_status = sender->termination_signal();
return;
}
[[fallthrough]];
case State::Dying:
if (sender->termination_signal() == 0) {
signal_info.si_code = CLD_EXITED;
signal_info.si_status = sender->termination_status();
return;
}
signal_info.si_code = CLD_KILLED;
signal_info.si_status = sender->termination_signal();
return;
case State::Runnable:
case State::Running:
case State::Blocked:
signal_info.si_code = CLD_CONTINUED;
return;
case State::Stopped:
signal_info.si_code = CLD_STOPPED;
return;
case State::Invalid:
// Something is wrong, but we're just an observer.
break;
}
}
signal_info.si_code = SI_NOINFO;
};
siginfo signal_info {
.si_signo = signal,
// Filled in below by fill_signal_info_for_signal.
.si_code = 0,
// Set for SI_TIMER, we don't have the data here.
.si_errno = 0,
.si_pid = sender_pid.value(),
.si_uid = sender ? sender->credentials()->uid().value() : 0,
// Set for SIGILL, SIGFPE, SIGSEGV and SIGBUS
// FIXME: We don't generate these signals in a way that can be handled.
.si_addr = 0,
// Set for SIGCHLD.
.si_status = 0,
// Set for SIGPOLL, we don't have SIGPOLL.
.si_band = 0,
// Set for SI_QUEUE, SI_TIMER, SI_ASYNCIO and SI_MESGQ
// We do not generate any of these.
.si_value = {
.sival_int = 0,
},
};
if (action.flags & SA_SIGINFO)
fill_signal_info_for_signal(signal_info);
#if ARCH(X86_64)
constexpr static FlatPtr thread_red_zone_size = 128;
#elif ARCH(AARCH64)
constexpr static FlatPtr thread_red_zone_size = 0; // FIXME
TODO_AARCH64();
#else
# error Unknown architecture in dispatch_signal
#endif
// Align the stack to 16 bytes.
// Note that we push some elements on to the stack before the return address,
// so we need to account for this here.
constexpr static FlatPtr elements_pushed_on_stack_before_handler_address = 1; // one slot for a saved register
FlatPtr const extra_bytes_pushed_on_stack_before_handler_address = sizeof(ucontext) + sizeof(signal_info);
FlatPtr stack_alignment = (stack - elements_pushed_on_stack_before_handler_address * sizeof(FlatPtr) + extra_bytes_pushed_on_stack_before_handler_address) % 16;
// Also note that we have to skip the thread red-zone (if needed), so do that here.
stack -= thread_red_zone_size + stack_alignment;
auto start_of_stack = stack;
TRY(push_value_on_user_stack(stack, 0)); // syscall return value slot
TRY(copy_value_on_user_stack(stack, ucontext));
auto pointer_to_ucontext = stack;
TRY(copy_value_on_user_stack(stack, signal_info));
auto pointer_to_signal_info = stack;
// Make sure we actually pushed as many elements as we claimed to have pushed.
if (start_of_stack - stack != elements_pushed_on_stack_before_handler_address * sizeof(FlatPtr) + extra_bytes_pushed_on_stack_before_handler_address) {
PANIC("Stack in invalid state after signal trampoline, expected {:x} but got {:x}",
start_of_stack - elements_pushed_on_stack_before_handler_address * sizeof(FlatPtr) - extra_bytes_pushed_on_stack_before_handler_address, stack);
}
VERIFY(stack % 16 == 0);
#if ARCH(X86_64)
// Save the FPU/SSE state
TRY(copy_value_on_user_stack(stack, fpu_state()));
#endif
TRY(push_value_on_user_stack(stack, pointer_to_ucontext));
TRY(push_value_on_user_stack(stack, pointer_to_signal_info));
TRY(push_value_on_user_stack(stack, signal));
TRY(push_value_on_user_stack(stack, handler_vaddr.get()));
// We write back the adjusted stack value into the register state.
// We have to do this because we can't just pass around a reference to a packed field, as it's UB.
state.set_userspace_sp(stack);
return {};
};
// We now place the thread state on the userspace stack.
// Note that we use a RegisterState.
// Conversely, when the thread isn't blocking the RegisterState may not be
// valid (fork, exec etc) but the tss will, so we use that instead.
auto& regs = get_register_dump_from_stack();
auto result = setup_stack(regs);
if (result.is_error()) {
dbgln("Invalid stack pointer: {}", regs.userspace_sp());
process.set_should_generate_coredump(true);
process.for_each_thread([](auto& thread) {
thread.set_dump_backtrace_on_finalization();
});
m_process->terminate_due_to_signal(signal);
return DispatchSignalResult::Terminate;
}
auto signal_trampoline_addr = process.signal_trampoline().get();
regs.set_ip(signal_trampoline_addr);
#if ARCH(X86_64)
// Userspace flags might be invalid for function entry, according to SYSV ABI (section 3.2.1).
// Set them to a known-good value to avoid weird handler misbehavior.
// Only IF (and the reserved bit 1) are set.
regs.set_flags(2 | (regs.rflags & ~safe_eflags_mask));
#endif
dbgln_if(SIGNAL_DEBUG, "Thread in state '{}' has been primed with signal handler {:p} to deliver {}", state_string(), m_regs.ip(), signal);
return DispatchSignalResult::Continue;
}
RegisterState& Thread::get_register_dump_from_stack()
{
auto* trap = current_trap();
// We should *always* have a trap. If we don't we're probably a kernel
// thread that hasn't been preempted. If we want to support this, we
// need to capture the registers probably into m_regs and return it
VERIFY(trap);
while (trap) {
if (!trap->next_trap)
break;
trap = trap->next_trap;
}
return *trap->regs;
}
ErrorOr<NonnullLockRefPtr<Thread>> Thread::try_clone(Process& process)
{
auto clone = TRY(Thread::try_create(process));
m_signal_action_masks.span().copy_to(clone->m_signal_action_masks);
clone->m_signal_mask = m_signal_mask;
clone->m_fpu_state = m_fpu_state;
clone->m_thread_specific_data = m_thread_specific_data;
return clone;
}
void Thread::set_state(State new_state, u8 stop_signal)
{
State previous_state;
VERIFY(g_scheduler_lock.is_locked_by_current_processor());
if (new_state == m_state)
return;
{
previous_state = m_state;
if (previous_state == Thread::State::Invalid) {
// If we were *just* created, we may have already pending signals
if (has_unmasked_pending_signals()) {
dbgln_if(THREAD_DEBUG, "Dispatch pending signals to new thread {}", *this);
dispatch_one_pending_signal();
}
}
m_state = new_state;
dbgln_if(THREAD_DEBUG, "Set thread {} state to {}", *this, state_string());
}
if (previous_state == Thread::State::Runnable) {
Scheduler::dequeue_runnable_thread(*this);
} else if (previous_state == Thread::State::Stopped) {
m_stop_state = State::Invalid;
auto& process = this->process();
if (process.set_stopped(false)) {
process.for_each_thread([&](auto& thread) {
if (&thread == this)
return;
if (!thread.is_stopped())
return;
dbgln_if(THREAD_DEBUG, "Resuming peer thread {}", thread);
thread.resume_from_stopped();
});
process.unblock_waiters(Thread::WaitBlocker::UnblockFlags::Continued);
// Tell the parent process (if any) about this change.
if (auto parent = Process::from_pid_ignoring_jails(process.ppid())) {
[[maybe_unused]] auto result = parent->send_signal(SIGCHLD, &process);
}
}
}
if (m_state == Thread::State::Runnable) {
Scheduler::enqueue_runnable_thread(*this);
Processor::smp_wake_n_idle_processors(1);
} else if (m_state == Thread::State::Stopped) {
// We don't want to restore to Running state, only Runnable!
m_stop_state = previous_state != Thread::State::Running ? previous_state : Thread::State::Runnable;
auto& process = this->process();
if (!process.set_stopped(true)) {
process.for_each_thread([&](auto& thread) {
if (&thread == this)
return;
if (thread.is_stopped())
return;
dbgln_if(THREAD_DEBUG, "Stopping peer thread {}", thread);
thread.set_state(Thread::State::Stopped, stop_signal);
});
process.unblock_waiters(Thread::WaitBlocker::UnblockFlags::Stopped, stop_signal);
// Tell the parent process (if any) about this change.
if (auto parent = Process::from_pid_ignoring_jails(process.ppid())) {
[[maybe_unused]] auto result = parent->send_signal(SIGCHLD, &process);
}
}
} else if (m_state == Thread::State::Dying) {
VERIFY(previous_state != Thread::State::Blocked);
if (this != Thread::current() && is_finalizable()) {
// Some other thread set this thread to Dying, notify the
// finalizer right away as it can be cleaned up now
Scheduler::notify_finalizer();
}
}
}
struct RecognizedSymbol {
FlatPtr address;
KernelSymbol const* symbol { nullptr };
};
static ErrorOr<bool> symbolicate(RecognizedSymbol const& symbol, Process& process, StringBuilder& builder)
{
if (symbol.address == 0)
return false;
auto credentials = process.credentials();
bool mask_kernel_addresses = !credentials->is_superuser();
if (!symbol.symbol) {
if (!Memory::is_user_address(VirtualAddress(symbol.address))) {
TRY(builder.try_append("0xdeadc0de\n"sv));
} else {
TRY(process.address_space().with([&](auto& space) -> ErrorOr<void> {
if (auto* region = space->find_region_containing({ VirtualAddress(symbol.address), sizeof(FlatPtr) })) {
size_t offset = symbol.address - region->vaddr().get();
if (auto region_name = region->name(); !region_name.is_null() && !region_name.is_empty())
TRY(builder.try_appendff("{:p} {} + {:#x}\n", (void*)symbol.address, region_name, offset));
else
TRY(builder.try_appendff("{:p} {:p} + {:#x}\n", (void*)symbol.address, region->vaddr().as_ptr(), offset));
} else {
TRY(builder.try_appendff("{:p}\n", symbol.address));
}
return {};
}));
}
return true;
}
unsigned offset = symbol.address - symbol.symbol->address;
if (symbol.symbol->address == g_highest_kernel_symbol_address && offset > 4096)
TRY(builder.try_appendff("{:p}\n", (void*)(mask_kernel_addresses ? 0xdeadc0de : symbol.address)));
else
TRY(builder.try_appendff("{:p} {} + {:#x}\n", (void*)(mask_kernel_addresses ? 0xdeadc0de : symbol.address), symbol.symbol->name, offset));
return true;
}
ErrorOr<NonnullOwnPtr<KString>> Thread::backtrace()
{
Vector<RecognizedSymbol, 128> recognized_symbols;
auto& process = const_cast<Process&>(this->process());
auto stack_trace = TRY(Processor::capture_stack_trace(*this));
VERIFY(!g_scheduler_lock.is_locked_by_current_processor());
ScopedAddressSpaceSwitcher switcher(process);
for (auto& frame : stack_trace) {
if (Memory::is_user_range(VirtualAddress(frame), sizeof(FlatPtr) * 2)) {
TRY(recognized_symbols.try_append({ frame }));
} else {
TRY(recognized_symbols.try_append({ frame, symbolicate_kernel_address(frame) }));
}
}
StringBuilder builder;
for (auto& symbol : recognized_symbols) {
if (!TRY(symbolicate(symbol, process, builder)))
break;
}
return KString::try_create(builder.string_view());
}
size_t Thread::thread_specific_region_alignment() const
{
return max(process().m_master_tls_alignment, alignof(ThreadSpecificData));
}
size_t Thread::thread_specific_region_size() const
{
return align_up_to(process().m_master_tls_size, thread_specific_region_alignment()) + sizeof(ThreadSpecificData);
}
ErrorOr<void> Thread::make_thread_specific_region(Badge<Process>)
{
// The process may not require a TLS region, or allocate TLS later with sys$allocate_tls (which is what dynamically loaded programs do)
if (!process().m_master_tls_region)
return {};
return process().address_space().with([&](auto& space) -> ErrorOr<void> {
auto* region = TRY(space->allocate_region(Memory::RandomizeVirtualAddress::Yes, {}, thread_specific_region_size(), PAGE_SIZE, "Thread-specific"sv, PROT_READ | PROT_WRITE));
m_thread_specific_range = region->range();
SmapDisabler disabler;
auto* thread_specific_data = (ThreadSpecificData*)region->vaddr().offset(align_up_to(process().m_master_tls_size, thread_specific_region_alignment())).as_ptr();
auto* thread_local_storage = (u8*)((u8*)thread_specific_data) - align_up_to(process().m_master_tls_size, process().m_master_tls_alignment);
m_thread_specific_data = VirtualAddress(thread_specific_data);
thread_specific_data->self = thread_specific_data;
if (process().m_master_tls_size != 0)
memcpy(thread_local_storage, process().m_master_tls_region.unsafe_ptr()->vaddr().as_ptr(), process().m_master_tls_size);
return {};
});
}
LockRefPtr<Thread> Thread::from_tid(ThreadID tid)
{
return Thread::all_instances().with([&](auto& list) -> LockRefPtr<Thread> {
for (Thread& thread : list) {
if (thread.tid() == tid)
return thread;
}
return nullptr;
});
}
void Thread::reset_fpu_state()
{
memcpy(&m_fpu_state, &Processor::clean_fpu_state(), sizeof(FPUState));
}
bool Thread::should_be_stopped() const
{
return process().is_stopped();
}
void Thread::track_lock_acquire(LockRank rank)
{
// Nothing to do for locks without a rank.
if (rank == LockRank::None)
return;
if (m_lock_rank_mask != LockRank::None) {
// Verify we are only attempting to take a lock of a higher rank.
VERIFY(m_lock_rank_mask > rank);
}
m_lock_rank_mask |= rank;
}
void Thread::track_lock_release(LockRank rank)
{
// Nothing to do for locks without a rank.
if (rank == LockRank::None)
return;
// The rank value from the caller should only contain a single bit, otherwise
// we are disabling the tracking for multiple locks at once which will corrupt
// the lock tracking mask, and we will assert somewhere else.
auto rank_is_a_single_bit = [](auto rank_enum) -> bool {
auto rank = to_underlying(rank_enum);
auto rank_without_least_significant_bit = rank - 1;
return (rank & rank_without_least_significant_bit) == 0;
};
// We can't release locks out of order, as that would violate the ranking.
// This is validated by toggling the least significant bit of the mask, and
// then bit wise or-ing the rank we are trying to release with the resulting
// mask. If the rank we are releasing is truly the highest rank then the mask
// we get back will be equal to the current mask stored on the thread.
auto rank_is_in_order = [](auto mask_enum, auto rank_enum) -> bool {
auto mask = to_underlying(mask_enum);
auto rank = to_underlying(rank_enum);
auto mask_without_least_significant_bit = mask - 1;
return ((mask & mask_without_least_significant_bit) | rank) == mask;
};
VERIFY(has_flag(m_lock_rank_mask, rank));
VERIFY(rank_is_a_single_bit(rank));
VERIFY(rank_is_in_order(m_lock_rank_mask, rank));
m_lock_rank_mask ^= rank;
}
void Thread::set_name(NonnullOwnPtr<KString> name)
{
m_name.with([&](auto& this_name) {
this_name = move(name);
});
}
}
ErrorOr<void> AK::Formatter<Kernel::Thread>::format(FormatBuilder& builder, Kernel::Thread const& value)
{
return value.process().name().with([&](auto& process_name) {
return AK::Formatter<FormatString>::format(
builder,
"{}({}:{})"sv, process_name->view(), value.pid().value(), value.tid().value());
});
}