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ladybird/Kernel/Thread.cpp
Andreas Kling d7ad082afa Kernel+LibELF: Stop doing ELF symbolication in the kernel 
Now that the CrashDaemon symbolicates crashes in userspace, let's take
this one step further and stop trying to symbolicate userspace programs
in the kernel at all.
2020-12-25 01:03:46 +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
klog() << "signal: Okay, " << *this << " {" << state_string() << "} has been primed with signal handler " << String::format("%w", m_tss.cs) << ":" << String::format("%x", m_tss.eip) << " to deliver " << 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));
}
KResultOr<u32> Thread::make_userspace_stack_for_main_thread(Vector<String> arguments, Vector<String> environment, Vector<AuxiliaryValue> auxiliary_values)
{
auto* region = m_process->allocate_region(VirtualAddress(), default_userspace_stack_size, "Stack (Main thread)", PROT_READ | PROT_WRITE, false);
if (!region)
return KResult(-ENOMEM);
region->set_stack(true);
FlatPtr new_esp = region->vaddr().offset(default_userspace_stack_size).get();
auto push_on_new_stack = [&new_esp](u32 value) {
new_esp -= 4;
Userspace<u32*> stack_ptr = new_esp;
return copy_to_user(stack_ptr, &value);
};
auto push_aux_value_on_new_stack = [&new_esp](auxv_t value) {
new_esp -= sizeof(auxv_t);
Userspace<auxv_t*> stack_ptr = new_esp;
return copy_to_user(stack_ptr, &value);
};
auto push_string_on_new_stack = [&new_esp](const String& string) {
new_esp -= round_up_to_power_of_two(string.length() + 1, 4);
Userspace<u32*> stack_ptr = new_esp;
return copy_to_user(stack_ptr, string.characters(), string.length() + 1);
};
Vector<FlatPtr> argv_entries;
for (auto& argument : arguments) {
push_string_on_new_stack(argument);
argv_entries.append(new_esp);
}
Vector<FlatPtr> env_entries;
for (auto& variable : environment) {
push_string_on_new_stack(variable);
env_entries.append(new_esp);
}
for (auto& value : auxiliary_values) {
if (!value.optional_string.is_empty()) {
push_string_on_new_stack(value.optional_string);
value.auxv.a_un.a_ptr = (void*)new_esp;
}
}
for (ssize_t i = auxiliary_values.size() - 1; i >= 0; --i) {
auto& value = auxiliary_values[i];
push_aux_value_on_new_stack(value.auxv);
}
push_on_new_stack(0);
for (ssize_t i = env_entries.size() - 1; i >= 0; --i)
push_on_new_stack(env_entries[i]);
FlatPtr envp = new_esp;
push_on_new_stack(0);
for (ssize_t i = argv_entries.size() - 1; i >= 0; --i)
push_on_new_stack(argv_entries[i]);
FlatPtr argv = new_esp;
// NOTE: The stack needs to be 16-byte aligned.
new_esp -= new_esp % 16;
push_on_new_stack((FlatPtr)envp);
push_on_new_stack((FlatPtr)argv);
push_on_new_stack((FlatPtr)argv_entries.size());
push_on_new_stack(0);
return new_esp;
}
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;
clone->m_thread_specific_region_size = m_thread_specific_region_size;
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;
}
KResult Thread::make_thread_specific_region(Badge<Process>)
{
// The process may not require a TLS region
if (!process().m_master_tls_region)
return KSuccess;
size_t thread_specific_region_alignment = max(process().m_master_tls_alignment, alignof(ThreadSpecificData));
m_thread_specific_region_size = align_up_to(process().m_master_tls_size, thread_specific_region_alignment) + sizeof(ThreadSpecificData);
auto* region = process().allocate_region({}, m_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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