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ladybird/Kernel/Thread.cpp
Andreas Kling c10e0adaca Kernel: Move perf event backtrace capture out of Thread class 
There's no need for this to be generic and support running from an
arbitrary thread context. Perf events are always generated from within
the thread being profiled, so take advantage of that to simplify the
code. Also use Vector capacity to avoid heap allocations.
2021-02-03 11:53:05 +01:00

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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Demangle.h>
#include <AK/ScopeGuard.h>
#include <AK/StringBuilder.h>
#include <AK/Time.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/KSyms.h>
#include <Kernel/PerformanceEventBuffer.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Thread.h>
#include <Kernel/ThreadTracer.h>
#include <Kernel/TimerQueue.h>
#include <Kernel/VM/MemoryManager.h>
#include <Kernel/VM/PageDirectory.h>
#include <Kernel/VM/ProcessPagingScope.h>
#include <LibC/signal_numbers.h>
namespace Kernel {
SpinLock<u8> Thread::g_tid_map_lock;
HashMap<ThreadID, Thread*>* Thread::g_tid_map;
void Thread::initialize()
{
g_tid_map = new HashMap<ThreadID, Thread*>();
}
Thread::Thread(NonnullRefPtr<Process> process)
: m_process(move(process))
, m_name(m_process->name())
{
bool is_first_thread = m_process->add_thread(*this);
ArmedScopeGuard guard([&]() {
drop_thread_count(is_first_thread);
});
if (is_first_thread) {
// First thread gets TID == PID
m_tid = m_process->pid().value();
} else {
m_tid = Process::allocate_pid().value();
}
{
ScopedSpinLock lock(g_tid_map_lock);
auto result = g_tid_map->set(m_tid, this);
ASSERT(result == AK::HashSetResult::InsertedNewEntry);
}
if constexpr (THREAD_DEBUG)
dbgln("Created new thread {}({}:{})", m_process->name(), m_process->pid().value(), m_tid.value());
set_default_signal_dispositions();
m_fpu_state = (FPUState*)kmalloc_aligned<16>(sizeof(FPUState));
reset_fpu_state();
memset(&m_tss, 0, sizeof(m_tss));
m_tss.iomapbase = sizeof(TSS32);
// Only IF is set when a process boots.
m_tss.eflags = 0x0202;
if (m_process->is_kernel_process()) {
m_tss.cs = GDT_SELECTOR_CODE0;
m_tss.ds = GDT_SELECTOR_DATA0;
m_tss.es = GDT_SELECTOR_DATA0;
m_tss.fs = GDT_SELECTOR_PROC;
m_tss.ss = GDT_SELECTOR_DATA0;
m_tss.gs = 0;
} else {
m_tss.cs = GDT_SELECTOR_CODE3 | 3;
m_tss.ds = GDT_SELECTOR_DATA3 | 3;
m_tss.es = GDT_SELECTOR_DATA3 | 3;
m_tss.fs = GDT_SELECTOR_DATA3 | 3;
m_tss.ss = GDT_SELECTOR_DATA3 | 3;
m_tss.gs = GDT_SELECTOR_TLS | 3;
}
m_tss.cr3 = m_process->page_directory().cr3();
m_kernel_stack_region = MM.allocate_kernel_region(default_kernel_stack_size, String::formatted("Kernel Stack (Thread {})", m_tid.value()), Region::Access::Read | Region::Access::Write, false, AllocationStrategy::AllocateNow);
if (!m_kernel_stack_region) {
// Abort creating this thread, was_created() will return false
return;
}
m_kernel_stack_region->set_stack(true);
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() & 0xfffffff8u;
if (m_process->is_kernel_process()) {
m_tss.esp = m_tss.esp0 = m_kernel_stack_top;
} else {
// Ring 3 processes get a separate stack for ring 0.
// The ring 3 stack will be assigned by exec().
m_tss.ss0 = GDT_SELECTOR_DATA0;
m_tss.esp0 = 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();
guard.disarm();
}
Thread::~Thread()
{
{
// We need to explicitly remove ourselves from the thread list
// here. We may get pre-empted in the middle of destructing this
// thread, which causes problems if the thread list is iterated.
// Specifically, if this is the last thread of a process, checking
// block conditions would access m_process, which would be in
// the middle of being destroyed.
ScopedSpinLock lock(g_scheduler_lock);
ASSERT(!m_process_thread_list_node.is_in_list());
// We shouldn't be queued
ASSERT(m_runnable_priority < 0);
}
{
ScopedSpinLock lock(g_tid_map_lock);
auto result = g_tid_map->remove(m_tid);
ASSERT(result);
}
}
void Thread::unblock_from_blocker(Blocker& blocker)
{
auto do_unblock = [&]() {
ScopedSpinLock scheduler_lock(g_scheduler_lock);
ScopedSpinLock block_lock(m_block_lock);
if (m_blocker != &blocker)
return;
if (!should_be_stopped() && !is_stopped())
unblock();
};
if (Processor::current().in_irq()) {
Processor::current().deferred_call_queue([do_unblock = move(do_unblock), self = make_weak_ptr()]() {
if (auto this_thread = self.strong_ref())
do_unblock();
});
} else {
do_unblock();
}
}
void Thread::unblock(u8 signal)
{
ASSERT(!Processor::current().in_irq());
ASSERT(g_scheduler_lock.own_lock());
ASSERT(m_block_lock.own_lock());
if (m_state != Thread::Blocked)
return;
ASSERT(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::Running);
return;
}
ASSERT(m_state != Thread::Runnable && m_state != Thread::Running);
set_state(Thread::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.
ScopedSpinLock 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
ASSERT(!process().is_stopped());
resume_from_stopped();
}
if (is_blocked()) {
ScopedSpinLock 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()
{
ASSERT(Thread::current() == this);
if (!m_should_die)
return;
u32 unlock_count;
[[maybe_unused]] auto rc = unlock_process_if_locked(unlock_count);
ScopedCritical critical;
set_should_die();
// Flag a context switch. Because we're in a critical section,
// Scheduler::yield will actually only mark a pending scontext 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
u32 prev_flags;
Processor::current().clear_critical(prev_flags, false);
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
ASSERT_NOT_REACHED();
}
void Thread::exit(void* exit_value)
{
ASSERT(Thread::current() == this);
m_join_condition.thread_did_exit(exit_value);
set_should_die();
u32 unlock_count;
[[maybe_unused]] auto rc = unlock_process_if_locked(unlock_count);
die_if_needed();
}
void Thread::yield_while_not_holding_big_lock()
{
ASSERT(!g_scheduler_lock.own_lock());
u32 prev_flags;
u32 prev_crit = Processor::current().clear_critical(prev_flags, true);
Scheduler::yield();
// NOTE: We may be on a different CPU now!
Processor::current().restore_critical(prev_crit, prev_flags);
}
void Thread::yield_without_holding_big_lock()
{
ASSERT(!g_scheduler_lock.own_lock());
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.
Scheduler::yield();
relock_process(previous_locked, lock_count_to_restore);
}
void Thread::donate_without_holding_big_lock(RefPtr<Thread>& thread, const char* reason)
{
ASSERT(!g_scheduler_lock.own_lock());
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.
Scheduler::donate_to(thread, reason);
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_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::donate_to or 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_flags;
u32 prev_crit = Processor::current().clear_critical(prev_flags, true);
// CONTEXT SWITCH HAPPENS HERE!
// NOTE: We may be on a different CPU now!
Processor::current().restore_critical(prev_crit, prev_flags);
if (previous_locked != LockMode::Unlocked) {
// We've unblocked, relock the process if needed and carry on.
RESTORE_LOCK(process().big_lock(), previous_locked, lock_count_to_restore);
}
}
auto Thread::sleep(clockid_t clock_id, const timespec& duration, timespec* remaining_time) -> BlockResult
{
ASSERT(state() == Thread::Running);
return Thread::current()->block<Thread::SleepBlocker>({}, Thread::BlockTimeout(false, &duration, nullptr, clock_id), remaining_time);
}
auto Thread::sleep_until(clockid_t clock_id, const timespec& deadline) -> BlockResult
{
ASSERT(state() == Thread::Running);
return Thread::current()->block<Thread::SleepBlocker>({}, Thread::BlockTimeout(true, &deadline, nullptr, clock_id));
}
const char* Thread::state_string() const
{
switch (state()) {
case Thread::Invalid:
return "Invalid";
case Thread::Runnable:
return "Runnable";
case Thread::Running:
return "Running";
case Thread::Dying:
return "Dying";
case Thread::Dead:
return "Dead";
case Thread::Stopped:
return "Stopped";
case Thread::Blocked: {
ScopedSpinLock block_lock(m_block_lock);
ASSERT(m_blocker != nullptr);
return m_blocker->state_string();
}
}
klog() << "Thread::state_string(): Invalid state: " << state();
ASSERT_NOT_REACHED();
return nullptr;
}
void Thread::finalize()
{
ASSERT(Thread::current() == g_finalizer);
ASSERT(Thread::current() != this);
#if LOCK_DEBUG
ASSERT(!m_lock.own_lock());
if (lock_count() > 0) {
dbgln("Thread {} leaking {} Locks!", *this, lock_count());
ScopedSpinLock list_lock(m_holding_locks_lock);
for (auto& info : m_holding_locks_list)
dbgln(" - {} @ {} locked at {}:{} count: {}", info.lock->name(), info.lock, info.file, info.line, info.count);
ASSERT_NOT_REACHED();
}
#endif
{
ScopedSpinLock lock(g_scheduler_lock);
dbgln<THREAD_DEBUG>("Finalizing thread {}", *this);
set_state(Thread::State::Dead);
m_join_condition.thread_finalizing();
}
if (m_dump_backtrace_on_finalization)
dbgln("{}", backtrace_impl());
kfree_aligned(m_fpu_state);
drop_thread_count(false);
}
void Thread::drop_thread_count(bool initializing_first_thread)
{
bool is_last = process().remove_thread(*this);
if (!initializing_first_thread && is_last)
process().finalize();
}
void Thread::finalize_dying_threads()
{
ASSERT(Thread::current() == g_finalizer);
Vector<Thread*, 32> dying_threads;
{
ScopedSpinLock lock(g_scheduler_lock);
for_each_in_state(Thread::State::Dying, [&](Thread& thread) {
if (thread.is_finalizable())
dying_threads.append(&thread);
return IterationDecision::Continue;
});
}
for (auto* thread : dying_threads) {
thread->finalize();
// 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();
}
}
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;
}
return --m_ticks_left;
}
void Thread::check_dispatch_pending_signal()
{
auto result = DispatchSignalResult::Continue;
{
ScopedSpinLock scheduler_lock(g_scheduler_lock);
if (pending_signals_for_state()) {
ScopedSpinLock lock(m_lock);
result = dispatch_one_pending_signal();
}
}
switch (result) {
case DispatchSignalResult::Yield:
yield_while_not_holding_big_lock();
break;
case DispatchSignalResult::Terminate:
process().die();
break;
default:
break;
}
}
bool Thread::has_pending_signal(u8 signal) const
{
ScopedSpinLock lock(g_scheduler_lock);
return pending_signals_for_state() & (1 << (signal - 1));
}
u32 Thread::pending_signals() const
{
ScopedSpinLock lock(g_scheduler_lock);
return pending_signals_for_state();
}
u32 Thread::pending_signals_for_state() const
{
ASSERT(g_scheduler_lock.own_lock());
constexpr u32 stopped_signal_mask = (1 << (SIGCONT - 1)) | (1 << (SIGKILL - 1)) | (1 << (SIGTRAP - 1));
if (is_handling_page_fault())
return 0;
return m_state != Stopped ? m_pending_signals : m_pending_signals & stopped_signal_mask;
}
void Thread::send_signal(u8 signal, [[maybe_unused]] Process* sender)
{
ASSERT(signal < 32);
ScopedSpinLock 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<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_have_any_unmasked_pending_signals.store(pending_signals_for_state() & ~m_signal_mask, AK::memory_order_release);
if (m_state == Stopped) {
ScopedSpinLock lock(m_lock);
if (pending_signals_for_state()) {
dbgln<SIGNAL_DEBUG>("Signal: Resuming stopped {} to deliver signal {}", *this, signal);
resume_from_stopped();
}
} else {
ScopedSpinLock block_lock(m_block_lock);
dbgln<SIGNAL_DEBUG>("Signal: Unblocking {} to deliver signal {}", *this, signal);
unblock(signal);
}
}
u32 Thread::update_signal_mask(u32 signal_mask)
{
ScopedSpinLock 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, AK::memory_order_release);
return previous_signal_mask;
}
u32 Thread::signal_mask() const
{
ScopedSpinLock lock(g_scheduler_lock);
return m_signal_mask;
}
u32 Thread::signal_mask_block(sigset_t signal_set, bool block)
{
ScopedSpinLock 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, AK::memory_order_release);
return previous_signal_mask;
}
void Thread::clear_signals()
{
ScopedSpinLock lock(g_scheduler_lock);
m_signal_mask = 0;
m_pending_signals = 0;
m_have_any_unmasked_pending_signals.store(false, AK::memory_order_release);
}
// 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)
{
ASSERT(Thread::current() == this);
DispatchSignalResult result;
{
ScopedSpinLock lock(g_scheduler_lock);
result = dispatch_signal(signal);
}
if (result == DispatchSignalResult::Yield)
yield_without_holding_big_lock();
}
DispatchSignalResult Thread::dispatch_one_pending_signal()
{
ASSERT(m_lock.own_lock());
u32 signal_candidates = pending_signals_for_state() & ~m_signal_mask;
if (signal_candidates == 0)
return DispatchSignalResult::Continue;
u8 signal = 1;
for (; signal < 32; ++signal) {
if (signal_candidates & (1 << (signal - 1))) {
break;
}
}
return dispatch_signal(signal);
}
DispatchSignalResult Thread::try_dispatch_one_pending_signal(u8 signal)
{
ASSERT(signal != 0);
ScopedSpinLock scheduler_lock(g_scheduler_lock);
ScopedSpinLock lock(m_lock);
u32 signal_candidates = pending_signals_for_state() & ~m_signal_mask;
if (!(signal_candidates & (1 << (signal - 1))))
return DispatchSignalResult::Continue;
return dispatch_signal(signal);
}
enum class DefaultSignalAction {
Terminate,
Ignore,
DumpCore,
Stop,
Continue,
};
static DefaultSignalAction default_signal_action(u8 signal)
{
ASSERT(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:
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;
}
ASSERT_NOT_REACHED();
}
bool Thread::should_ignore_signal(u8 signal) const
{
ASSERT(signal < 32);
auto& action = m_signal_action_data[signal];
if (action.handler_or_sigaction.is_null())
return default_signal_action(signal) == DefaultSignalAction::Ignore;
if (action.handler_or_sigaction.as_ptr() == SIG_IGN)
return true;
return false;
}
bool Thread::has_signal_handler(u8 signal) const
{
ASSERT(signal < 32);
auto& action = m_signal_action_data[signal];
return !action.handler_or_sigaction.is_null();
}
static bool push_value_on_user_stack(u32* stack, u32 data)
{
*stack -= 4;
return copy_to_user((u32*)*stack, &data);
}
void Thread::resume_from_stopped()
{
ASSERT(is_stopped());
ASSERT(m_stop_state != State::Invalid);
ASSERT(g_scheduler_lock.own_lock());
if (m_stop_state == Blocked) {
ScopedSpinLock block_lock(m_block_lock);
if (m_blocker) {
// Hasn't been unblocked yet
set_state(Blocked, 0);
} else {
// Was unblocked while stopped
set_state(Runnable);
}
} else {
set_state(m_stop_state, 0);
}
}
DispatchSignalResult Thread::dispatch_signal(u8 signal)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(g_scheduler_lock.own_lock());
ASSERT(signal > 0 && signal <= 32);
ASSERT(process().is_user_process());
ASSERT(this == Thread::current());
#if SIGNAL_DEBUG
klog() << "signal: dispatch signal " << signal << " to " << *this << " state: " << state_string();
#endif
if (m_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;
}
ASSERT(previous_mode() == PreviousMode::UserMode);
auto& action = m_signal_action_data[signal];
// FIXME: Implement SA_SIGINFO signal handlers.
ASSERT(!(action.flags & SA_SIGINFO));
// Mark this signal as handled.
m_pending_signals &= ~(1 << (signal - 1));
m_have_any_unmasked_pending_signals.store(m_pending_signals & ~m_signal_mask, AK::memory_order_release);
auto& process = this->process();
auto tracer = process.tracer();
if (signal == SIGSTOP || (tracer && default_signal_action(signal) == DefaultSignalAction::DumpCore)) {
dbgln<SIGNAL_DEBUG>("signal: signal {} sopping thread {}", signal, *this);
set_state(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(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(Stopped, signal);
return DispatchSignalResult::Yield;
case DefaultSignalAction::DumpCore:
process.set_dump_core(true);
process.for_each_thread([](auto& thread) {
thread.set_dump_backtrace_on_finalization();
return IterationDecision::Continue;
});
[[fallthrough]];
case DefaultSignalAction::Terminate:
m_process->terminate_due_to_signal(signal);
return DispatchSignalResult::Terminate;
case DefaultSignalAction::Ignore:
ASSERT_NOT_REACHED();
case DefaultSignalAction::Continue:
return DispatchSignalResult::Continue;
}
ASSERT_NOT_REACHED();
}
if (handler_vaddr.as_ptr() == SIG_IGN) {
#if SIGNAL_DEBUG
klog() << "signal: " << *this << " ignored signal " << signal;
#endif
return DispatchSignalResult::Continue;
}
ASSERT(previous_mode() == PreviousMode::UserMode);
ASSERT(current_trap());
ProcessPagingScope paging_scope(m_process);
u32 old_signal_mask = m_signal_mask;
u32 new_signal_mask = action.mask;
if (action.flags & 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, AK::memory_order_release);
auto setup_stack = [&](RegisterState& state) {
u32* stack = &state.userspace_esp;
u32 old_esp = *stack;
u32 ret_eip = state.eip;
u32 ret_eflags = state.eflags;
#if SIGNAL_DEBUG
klog() << "signal: setting up user stack to return to eip: " << String::format("%p", (void*)ret_eip) << " esp: " << String::format("%p", (void*)old_esp);
#endif
// Align the stack to 16 bytes.
// Note that we push 56 bytes (4 * 14) on to the stack,
// so we need to account for this here.
u32 stack_alignment = (*stack - 56) % 16;
*stack -= stack_alignment;
push_value_on_user_stack(stack, ret_eflags);
push_value_on_user_stack(stack, ret_eip);
push_value_on_user_stack(stack, state.eax);
push_value_on_user_stack(stack, state.ecx);
push_value_on_user_stack(stack, state.edx);
push_value_on_user_stack(stack, state.ebx);
push_value_on_user_stack(stack, old_esp);
push_value_on_user_stack(stack, state.ebp);
push_value_on_user_stack(stack, state.esi);
push_value_on_user_stack(stack, state.edi);
// PUSH old_signal_mask
push_value_on_user_stack(stack, old_signal_mask);
push_value_on_user_stack(stack, signal);
push_value_on_user_stack(stack, handler_vaddr.get());
push_value_on_user_stack(stack, 0); //push fake return address
ASSERT((*stack % 16) == 0);
};
// 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();
setup_stack(regs);
regs.eip = g_return_to_ring3_from_signal_trampoline.get();
#if SIGNAL_DEBUG
dbgln("signal: Thread in state '{}' has been primed with signal handler {:04x}:{:08x} to deliver {}", state_string(), m_tss.cs, m_tss.eip, signal);
#endif
return DispatchSignalResult::Continue;
}
void Thread::set_default_signal_dispositions()
{
// FIXME: Set up all the right default actions. See signal(7).
memset(&m_signal_action_data, 0, sizeof(m_signal_action_data));
m_signal_action_data[SIGCHLD].handler_or_sigaction = VirtualAddress(SIG_IGN);
m_signal_action_data[SIGWINCH].handler_or_sigaction = VirtualAddress(SIG_IGN);
}
bool Thread::push_value_on_stack(FlatPtr value)
{
m_tss.esp -= 4;
FlatPtr* stack_ptr = (FlatPtr*)m_tss.esp;
return copy_to_user(stack_ptr, &value);
}
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 pre-empted. If we want to support this, we
// need to capture the registers probably into m_tss and return it
ASSERT(trap);
while (trap) {
if (!trap->next_trap)
break;
trap = trap->next_trap;
}
return *trap->regs;
}
RefPtr<Thread> Thread::clone(Process& process)
{
auto clone = adopt(*new Thread(process));
if (!clone->was_created()) {
// We failed to clone this thread
return {};
}
memcpy(clone->m_signal_action_data, m_signal_action_data, sizeof(m_signal_action_data));
clone->m_signal_mask = m_signal_mask;
memcpy(clone->m_fpu_state, m_fpu_state, sizeof(FPUState));
clone->m_thread_specific_data = m_thread_specific_data;
return clone;
}
void Thread::set_state(State new_state, u8 stop_signal)
{
State previous_state;
ASSERT(g_scheduler_lock.own_lock());
if (new_state == m_state)
return;
{
ScopedSpinLock thread_lock(m_lock);
previous_state = m_state;
if (previous_state == Invalid) {
// If we were *just* created, we may have already pending signals
if (has_unmasked_pending_signals()) {
dbgln<THREAD_DEBUG>("Dispatch pending signals to new thread {}", *this);
dispatch_one_pending_signal();
}
}
m_state = new_state;
dbgln<THREAD_DEBUG>("Set thread {} state to {}", *this, state_string());
}
if (previous_state == Runnable) {
Scheduler::dequeue_runnable_thread(*this);
} else if (previous_state == Stopped) {
m_stop_state = State::Invalid;
auto& process = this->process();
if (process.set_stopped(false) == true) {
process.for_each_thread([&](auto& thread) {
if (&thread == this || !thread.is_stopped())
return IterationDecision::Continue;
dbgln<THREAD_DEBUG>("Resuming peer thread {}", thread);
thread.resume_from_stopped();
return IterationDecision::Continue;
});
process.unblock_waiters(Thread::WaitBlocker::UnblockFlags::Continued);
}
}
if (m_state == Runnable) {
Scheduler::queue_runnable_thread(*this);
Processor::smp_wake_n_idle_processors(1);
} else if (m_state == Stopped) {
// We don't want to restore to Running state, only Runnable!
m_stop_state = previous_state != Running ? previous_state : Runnable;
auto& process = this->process();
if (process.set_stopped(true) == false) {
process.for_each_thread([&](auto& thread) {
if (&thread == this || thread.is_stopped())
return IterationDecision::Continue;
dbgln<THREAD_DEBUG>("Stopping peer thread {}", thread);
thread.set_state(Stopped, stop_signal);
return IterationDecision::Continue;
});
process.unblock_waiters(Thread::WaitBlocker::UnblockFlags::Stopped, stop_signal);
}
} else if (m_state == Dying) {
ASSERT(previous_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();
}
}
}
String Thread::backtrace()
{
return backtrace_impl();
}
struct RecognizedSymbol {
u32 address;
const KernelSymbol* symbol { nullptr };
};
static bool symbolicate(const RecognizedSymbol& symbol, const Process& process, StringBuilder& builder)
{
if (!symbol.address)
return false;
bool mask_kernel_addresses = !process.is_superuser();
if (!symbol.symbol) {
if (!is_user_address(VirtualAddress(symbol.address))) {
builder.append("0xdeadc0de\n");
} else {
builder.appendff("{:p}\n", symbol.address);
}
return true;
}
unsigned offset = symbol.address - symbol.symbol->address;
if (symbol.symbol->address == g_highest_kernel_symbol_address && offset > 4096) {
builder.appendf("%p\n", (void*)(mask_kernel_addresses ? 0xdeadc0de : symbol.address));
} else {
builder.appendf("%p %s +%u\n", (void*)(mask_kernel_addresses ? 0xdeadc0de : symbol.address), demangle(symbol.symbol->name).characters(), offset);
}
return true;
}
String Thread::backtrace_impl()
{
Vector<RecognizedSymbol, 128> recognized_symbols;
auto& process = const_cast<Process&>(this->process());
auto stack_trace = Processor::capture_stack_trace(*this);
ASSERT(!g_scheduler_lock.own_lock());
ProcessPagingScope paging_scope(process);
for (auto& frame : stack_trace) {
if (is_user_range(VirtualAddress(frame), sizeof(FlatPtr) * 2)) {
recognized_symbols.append({ frame });
} else {
recognized_symbols.append({ frame, symbolicate_kernel_address(frame) });
}
}
StringBuilder builder;
for (auto& symbol : recognized_symbols) {
if (!symbolicate(symbol, process, builder))
break;
}
return builder.to_string();
}
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);
}
KResult Thread::make_thread_specific_region(Badge<Process>)
{
// The process may not require a TLS region
if (!process().m_master_tls_region)
return KSuccess;
auto range = process().allocate_range({}, thread_specific_region_size());
if (!range.has_value())
return ENOMEM;
auto region_or_error = process().allocate_region(range.value(), "Thread-specific", PROT_READ | PROT_WRITE);
if (region_or_error.is_error())
return region_or_error.error();
SmapDisabler disabler;
auto* thread_specific_data = (ThreadSpecificData*)region_or_error.value()->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)
memcpy(thread_local_storage, process().m_master_tls_region.unsafe_ptr()->vaddr().as_ptr(), process().m_master_tls_size);
return KSuccess;
}
const LogStream& operator<<(const LogStream& stream, const Thread& value)
{
return stream << value.process().name() << "(" << value.pid().value() << ":" << value.tid().value() << ")";
}
RefPtr<Thread> Thread::from_tid(ThreadID tid)
{
RefPtr<Thread> found_thread;
{
ScopedSpinLock lock(g_tid_map_lock);
auto it = g_tid_map->find(tid);
if (it != g_tid_map->end())
found_thread = it->value;
}
return found_thread;
}
void Thread::reset_fpu_state()
{
memcpy(m_fpu_state, &Processor::current().clean_fpu_state(), sizeof(FPUState));
}
bool Thread::should_be_stopped() const
{
return process().is_stopped();
}
}
void AK::Formatter<Kernel::Thread>::format(FormatBuilder& builder, const Kernel::Thread& value)
{
return AK::Formatter<FormatString>::format(
builder,
"{}({}:{})", value.process().name(), value.pid().value(), value.tid().value());
}
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