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ladybird/Kernel/Thread.cpp
kleines Filmröllchen a6a439243f Kernel: Turn lock ranks into template parameters 
This step would ideally not have been necessary (increases amount of
refactoring and templates necessary, which in turn increases build
times), but it gives us a couple of nice properties:
- SpinlockProtected inside Singleton (a very common combination) can now
  obtain any lock rank just via the template parameter. It was not
  previously possible to do this with SingletonInstanceCreator magic.
- SpinlockProtected's lock rank is now mandatory; this is the majority
  of cases and allows us to see where we're still missing proper ranks.
- The type already informs us what lock rank a lock has, which aids code
  readability and (possibly, if gdb cooperates) lock mismatch debugging.
- The rank of a lock can no longer be dynamic, which is not something we
  wanted in the first place (or made use of). Locks randomly changing
  their rank sounds like a disaster waiting to happen.
- In some places, we might be able to statically check that locks are
  taken in the right order (with the right lock rank checking
  implementation) as rank information is fully statically known.

This refactoring even more exposes the fact that Mutex has no lock rank
capabilites, which is not fixed here.
2023-01-02 18:15:27 -05:00

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/*
* 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/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/PageDirectory.h>
#include <Kernel/Memory/ScopedAddressSpaceSwitcher.h>
#include <Kernel/Panic.h>
#include <Kernel/PerformanceEventBuffer.h>
#include <Kernel/Process.h>
#include <Kernel/ProcessExposed.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>
#include <LibC/signal_numbers.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(KString::try_create(process->name()));
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)
dbgln("Created new thread {}({}:{})", m_process->name(), 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() == PreviousMode::KernelMode) {
++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);
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;
}
}
ErrorOr<void> AK::Formatter<Kernel::Thread>::format(FormatBuilder& builder, Kernel::Thread const& value)
{
return AK::Formatter<FormatString>::format(
builder,
"{}({}:{})"sv, value.process().name(), value.pid().value(), value.tid().value());
}
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