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ladybird/Kernel/Thread.cpp
Andreas Kling ed5c26d698 AK: Remove custom %w format string specifier 
This was a non-standard specifier alias for %04x. This patch replaces
all uses of it with new-style formatting functions instead.
2020-12-25 17:05:05 +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/StringBuilder.h>
#include <AK/Time.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/KSyms.h>
#include <Kernel/Process.h>
#include <Kernel/Profiling.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>
//#define SIGNAL_DEBUG
//#define THREAD_DEBUG
namespace Kernel {
Thread::Thread(NonnullRefPtr<Process> process)
: m_process(move(process))
, m_name(m_process->name())
{
if (m_process->m_thread_count.fetch_add(1, AK::MemoryOrder::memory_order_relaxed) == 0) {
// First thread gets TID == PID
m_tid = m_process->pid().value();
} else {
m_tid = Process::allocate_pid().value();
}
#ifdef THREAD_DEBUG
dbg() << "Created new thread " << m_process->name() << "(" << m_process->pid().value() << ":" << m_tid.value() << ")";
#endif
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::format("Kernel Stack (Thread %d)", m_tid.value()), Region::Access::Read | Region::Access::Write, false, true);
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();
if (m_process->pid() != 0)
Scheduler::init_thread(*this);
}
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);
g_scheduler_data->thread_list_for_state(m_state).remove(*this);
}
}
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 (!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) {
#ifdef THREAD_DEBUG
dbg() << *this << " Should already die";
#endif
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);
dbg() << "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>(nullptr, 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>(nullptr, 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);
#ifdef LOCK_DEBUG
ASSERT(!m_lock.own_lock());
if (lock_count() > 0) {
dbg() << "Thread " << *this << " leaking " << lock_count() << " Locks!";
ScopedSpinLock list_lock(m_holding_locks_lock);
for (auto& info : m_holding_locks_list)
dbg() << " - " << info.lock->name() << " @ " << info.lock << " locked at " << info.file << ":" << info.line << " count: " << info.count;
ASSERT_NOT_REACHED();
}
#endif
{
ScopedSpinLock lock(g_scheduler_lock);
#ifdef THREAD_DEBUG
dbg() << "Finalizing thread " << *this;
#endif
set_state(Thread::State::Dead);
m_join_condition.thread_finalizing();
}
if (m_dump_backtrace_on_finalization)
dbg() << backtrace_impl();
kfree_aligned(m_fpu_state);
auto thread_cnt_before = m_process->m_thread_count.fetch_sub(1, AK::MemoryOrder::memory_order_acq_rel);
ASSERT(thread_cnt_before != 0);
if (thread_cnt_before == 1)
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(bool in_kernel)
{
if (in_kernel) {
++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));
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)) {
#ifdef SIGNAL_DEBUG
dbg() << "Signal " << signal << " was ignored by " << process();
#endif
return;
}
#ifdef SIGNAL_DEBUG
if (sender)
dbg() << "Signal: " << *sender << " sent " << signal << " to " << process();
else
dbg() << "Signal: Kernel sent " << signal << " to " << process();
#endif
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()) {
#ifdef SIGNAL_DEBUG
dbg() << "Signal: Resuming stopped " << *this << " to deliver signal " << signal;
#endif
resume_from_stopped();
}
} else {
ScopedSpinLock block_lock(m_block_lock);
#ifdef SIGNAL_DEBUG
dbg() << "Signal: Unblocking " << *this << " to deliver signal " << signal;
#endif
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());
#ifdef 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;
}
// if (is_stopped() && signal != SIGCONT && signal != SIGKILL && signal != SIGTRAP) {
//#ifdef SIGNAL_DEBUG
// klog() << "signal: " << *this << " is stopped, will handle signal " << signal << " when resumed";
//#endif
// return DispatchSignalResult::Deferred;
// }
// if (is_blocked()) {
//#ifdef SIGNAL_DEBUG
// klog() << "signal: " << *this << " is blocked, will handle signal " << signal << " when unblocking";
//#endif
// return DispatchSignalResult::Deferred;
// }
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)) {
#ifdef SIGNAL_DEBUG
dbg() << "signal: signal " << signal << " stopping thread " << *this;
#endif
set_state(State::Stopped, signal);
return DispatchSignalResult::Yield;
}
if (signal == SIGCONT) {
#ifdef SIGNAL_DEBUG
dbg() << "signal: SIGCONT resuming " << *this;
#endif
} 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)) {
#ifdef SIGNAL_DEBUG
dbg() << "signal: " << signal << " stopping " << *this << " for tracer";
#endif
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) {
#ifdef SIGNAL_DEBUG
klog() << "signal: " << *this << " ignored signal " << signal;
#endif
return DispatchSignalResult::Continue;
}
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;
#ifdef SIGNAL_DEBUG
klog() << "signal: setting up user stack to return to eip: " << String::format("%p", ret_eip) << " esp: " << String::format("%p", 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();
#ifdef 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()
{
return *(RegisterState*)(kernel_stack_top() - sizeof(RegisterState));
}
RefPtr<Thread> Thread::clone(Process& process)
{
auto clone = adopt(*new Thread(process));
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()) {
dbg() << "Dispatch pending signals to new thread " << *this;
dispatch_one_pending_signal();
}
}
m_state = new_state;
#ifdef THREAD_DEBUG
dbg() << "Set Thread " << *this << " state to " << state_string();
#endif
}
if (m_process->pid() != 0) {
update_state_for_thread(previous_state);
ASSERT(g_scheduler_data->has_thread(*this));
}
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;
#ifdef THREAD_DEBUG
dbg() << "Resuming peer thread " << thread;
#endif
thread.resume_from_stopped();
return IterationDecision::Continue;
});
process.unblock_waiters(Thread::WaitBlocker::UnblockFlags::Continued);
}
}
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;
#ifdef THREAD_DEBUG
dbg() << "Stopping peer thread " << thread;
#endif
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();
}
}
}
void Thread::update_state_for_thread(Thread::State previous_state)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(g_scheduler_data);
ASSERT(g_scheduler_lock.own_lock());
auto& previous_list = g_scheduler_data->thread_list_for_state(previous_state);
auto& list = g_scheduler_data->thread_list_for_state(state());
if (&previous_list != &list) {
previous_list.remove(*this);
}
if (list.contains(*this))
return;
list.append(*this);
}
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", mask_kernel_addresses ? 0xdeadc0de : symbol.address);
} else {
builder.appendf("%p %s +%u\n", 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, symbolicate_kernel_address(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();
}
Vector<FlatPtr> Thread::raw_backtrace(FlatPtr ebp, FlatPtr eip) const
{
InterruptDisabler disabler;
auto& process = const_cast<Process&>(this->process());
ProcessPagingScope paging_scope(process);
Vector<FlatPtr, Profiling::max_stack_frame_count> backtrace;
backtrace.append(eip);
FlatPtr stack_ptr_copy;
FlatPtr stack_ptr = (FlatPtr)ebp;
while (stack_ptr) {
void* fault_at;
if (!safe_memcpy(&stack_ptr_copy, (void*)stack_ptr, sizeof(FlatPtr), fault_at))
break;
FlatPtr retaddr;
if (!safe_memcpy(&retaddr, (void*)(stack_ptr + sizeof(FlatPtr)), sizeof(FlatPtr), fault_at))
break;
backtrace.append(retaddr);
if (backtrace.size() == Profiling::max_stack_frame_count)
break;
stack_ptr = stack_ptr_copy;
}
return backtrace;
}
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* region = process().allocate_region({}, thread_specific_region_size(), "Thread-specific", PROT_READ | PROT_WRITE, true);
if (!region)
return KResult(-ENOMEM);
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)
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_scheduler_lock);
Thread::for_each([&](auto& thread) {
if (thread.tid() == tid) {
found_thread = &thread;
return IterationDecision::Break;
}
return IterationDecision::Continue;
});
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();
}
}
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