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Kernel: Fix signal generation

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We need to have interrupts enabled when signal kills the process as
process does mutex locking. Also signals are now only checked when
returning to userspace in the same place where userspace segments are
loaded.
This commit is contained in:
Bananymous
2026-04-04 22:36:54 +03:00
parent 47d85eb281
commit a29681a524
7 changed files with 166 additions and 143 deletions
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26
kernel/kernel/IDT.cpp
View File

@@ -221,7 +221,13 @@ namespace Kernel
if (result.is_error())
{
dwarnln("Demand paging: {}", result.error());
// TODO: this is too strict, we should maybe do SIGBUS and
// SIGKILL only on recursive exceptions
Processor::set_interrupt_state(InterruptState::Enabled);
Thread::current().handle_signal(SIGKILL, {});
Processor::set_interrupt_state(InterruptState::Disabled);
return;
}
@@ -321,7 +327,7 @@ namespace Kernel
Debug::s_debug_lock.unlock(InterruptState::Disabled);
if (tid && Thread::current().is_userspace())
if (tid && GDT::is_user_segment(interrupt_stack->cs))
{
// TODO: Confirm and fix the exception to signal mappings
@@ -366,7 +372,9 @@ namespace Kernel
break;
}
Processor::set_interrupt_state(InterruptState::Enabled);
Thread::current().handle_signal(signal_info.si_signo, signal_info);
Processor::set_interrupt_state(InterruptState::Disabled);
}
else
{
@@ -401,10 +409,6 @@ namespace Kernel
Process::update_alarm_queue();
Processor::scheduler().timer_interrupt();
auto& current_thread = Thread::current();
if (current_thread.can_add_signal_to_execute())
current_thread.handle_signal();
}
extern "C" void cpp_irq_handler(uint32_t irq)
@@ -428,15 +432,18 @@ namespace Kernel
else
dprintln("no handler for irq 0x{2H}", irq);
auto& current_thread = Thread::current();
if (current_thread.can_add_signal_to_execute())
current_thread.handle_signal();
Processor::scheduler().reschedule_if_idle();
ASSERT(Thread::current().state() != Thread::State::Terminated);
}
extern "C" void cpp_check_signal()
{
Processor::set_interrupt_state(InterruptState::Enabled);
Thread::current().handle_signal_if_interrupted();
Processor::set_interrupt_state(InterruptState::Disabled);
}
void IDT::register_interrupt_handler(uint8_t index, void (*handler)(), uint8_t ist)
{
auto& desc = m_idt[index];
@@ -476,7 +483,6 @@ namespace Kernel
IRQ_LIST_X
#undef X
extern "C" void asm_yield_handler();
extern "C" void asm_ipi_handler();
extern "C" void asm_timer_handler();
#if ARCH(i686)

9
kernel/kernel/Process.cpp
View File

@@ -303,6 +303,8 @@ namespace Kernel
void Process::exit(int status, int signal)
{
ASSERT(Processor::get_interrupt_state() == InterruptState::Enabled);
bool expected = false;
if (!m_is_exiting.compare_exchange(expected, true))
{
@@ -310,9 +312,6 @@ namespace Kernel
ASSERT_NOT_REACHED();
}
const auto state = Processor::get_interrupt_state();
Processor::set_interrupt_state(InterruptState::Enabled);
if (m_parent)
{
Process* parent_process = nullptr;
@@ -369,8 +368,6 @@ namespace Kernel
while (m_threads.size() > 1)
Processor::yield();
Processor::set_interrupt_state(state);
Thread::current().on_exit();
ASSERT_NOT_REACHED();
@@ -2951,7 +2948,7 @@ namespace Kernel
for (;;)
{
while (Thread::current().will_exit_because_of_signal())
Thread::current().handle_signal();
Thread::current().handle_signal_if_interrupted();
SpinLockGuard guard(m_signal_lock);
if (!m_stopped)

10
kernel/kernel/Syscall.cpp
View File

@@ -94,13 +94,11 @@ namespace Kernel
Process::current().wait_while_stopped();
Processor::set_interrupt_state(InterruptState::Disabled);
if (Thread::current().handle_signal_if_interrupted())
if (ret.is_error() && ret.error().get_error_code() == EINTR && is_restartable_syscall(syscall))
ret = BAN::Error::from_errno(ERESTART);
auto& current_thread = Thread::current();
if (current_thread.can_add_signal_to_execute())
if (current_thread.handle_signal())
if (ret.is_error() && ret.error().get_error_code() == EINTR && is_restartable_syscall(syscall))
ret = BAN::Error::from_errno(ERESTART);
Processor::set_interrupt_state(InterruptState::Disabled);
ASSERT(Kernel::Thread::current().state() == Kernel::Thread::State::Executing);

152
kernel/kernel/Thread.cpp
View File

@@ -572,19 +572,6 @@ namespace Kernel
return false;
}
bool Thread::can_add_signal_to_execute() const
{
return is_interrupted_by_signal() && m_mutex_count == 0;
}
bool Thread::will_execute_signal() const
{
if (!is_userspace() || m_state != State::Executing)
return false;
auto& interrupt_stack = *reinterpret_cast<InterruptStack*>(kernel_stack_top() - sizeof(InterruptStack));
return interrupt_stack.ip == (uintptr_t)signal_trampoline;
}
bool Thread::will_exit_because_of_signal() const
{
const uint64_t full_pending_mask = m_signal_pending_mask | process().signal_pending_mask();
@@ -596,21 +583,17 @@ namespace Kernel
return false;
}
bool Thread::handle_signal(int signal, const siginfo_t& _signal_info)
bool Thread::handle_signal_if_interrupted()
{
ASSERT(&Thread::current() == this);
ASSERT(is_userspace());
int signal;
siginfo_t signal_info;
signal_handle_info_t handle_info;
auto state = m_signal_lock.lock();
auto& interrupt_stack = *reinterpret_cast<InterruptStack*>(kernel_stack_top() - sizeof(InterruptStack));
ASSERT(GDT::is_user_segment(interrupt_stack.cs));
auto signal_info = _signal_info;
if (signal == 0)
{
const uint64_t process_signal_pending_mask = process().signal_pending_mask();
SpinLockGuard _1(m_signal_lock);
SpinLockGuard _2(m_process->m_signal_lock);
const uint64_t process_signal_pending_mask = m_process->m_signal_pending_mask;
const uint64_t full_pending_mask = m_signal_pending_mask | process_signal_pending_mask;
for (signal = _SIGMIN; signal <= _SIGMAX; signal++)
{
@@ -618,42 +601,77 @@ namespace Kernel
if ((full_pending_mask & mask) && !(m_signal_block_mask & mask))
break;
}
ASSERT(signal <= _SIGMAX);
if (signal > _SIGMAX)
return false;
if (process_signal_pending_mask & (1ull << signal))
signal_info = process().m_signal_infos[signal];
signal_info = m_process->m_signal_infos[signal];
else
signal_info = m_signal_infos[signal];
}
else
{
ASSERT(signal >= _SIGMIN);
ASSERT(signal <= _SIGMAX);
handle_info = remove_signal_and_get_info(signal);
}
vaddr_t signal_handler;
bool has_sa_restart;
handle_signal_impl(
signal,
signal_info,
handle_info.signal_handler,
handle_info.signal_stack_top
);
return handle_info.has_sa_restart;
}
bool Thread::handle_signal(int signal, const siginfo_t& signal_info)
{
ASSERT(&Thread::current() == this);
ASSERT(is_userspace());
ASSERT(signal >= _SIGMIN);
ASSERT(signal <= _SIGMAX);
signal_handle_info_t handle_info;
{
SpinLockGuard _1(m_signal_lock);
SpinLockGuard _2(m_process->m_signal_lock);
handle_info = remove_signal_and_get_info(signal);
}
handle_signal_impl(
signal,
signal_info,
handle_info.signal_handler,
handle_info.signal_stack_top
);
return handle_info.has_sa_restart;
}
Thread::signal_handle_info_t Thread::remove_signal_and_get_info(int signal)
{
ASSERT(m_signal_lock.current_processor_has_lock());
ASSERT(m_process->m_signal_lock.current_processor_has_lock());
ASSERT(signal >= _SIGMIN);
ASSERT(signal <= _SIGMAX);
auto& handler = m_process->m_signal_handlers[signal];
const vaddr_t signal_handler = (handler.sa_flags & SA_SIGINFO)
? reinterpret_cast<vaddr_t>(handler.sa_sigaction)
: reinterpret_cast<vaddr_t>(handler.sa_handler);
const bool has_sa_restart = !!(handler.sa_flags & SA_RESTART);
vaddr_t signal_stack_top = 0;
if (m_signal_alt_stack.ss_flags != SS_DISABLE && (handler.sa_flags & SA_ONSTACK) && !currently_on_alternate_stack())
signal_stack_top = reinterpret_cast<vaddr_t>(m_signal_alt_stack.ss_sp) + m_signal_alt_stack.ss_size;
{
SpinLockGuard _(m_process->m_signal_lock);
auto& handler = m_process->m_signal_handlers[signal];
signal_handler = (handler.sa_flags & SA_SIGINFO)
? reinterpret_cast<vaddr_t>(handler.sa_sigaction)
: reinterpret_cast<vaddr_t>(handler.sa_handler);
has_sa_restart = !!(handler.sa_flags & SA_RESTART);
const auto& alt_stack = m_signal_alt_stack;
if (alt_stack.ss_flags != SS_DISABLE && (handler.sa_flags & SA_ONSTACK) && !currently_on_alternate_stack())
signal_stack_top = reinterpret_cast<vaddr_t>(alt_stack.ss_sp) + alt_stack.ss_size;
if (handler.sa_flags & SA_RESETHAND)
handler = { .sa_handler = SIG_DFL, .sa_mask = 0, .sa_flags = 0 };
}
if (handler.sa_flags & SA_RESETHAND)
handler = { .sa_handler = SIG_DFL, .sa_mask = 0, .sa_flags = 0 };
m_signal_pending_mask &= ~(1ull << signal);
process().remove_pending_signal(signal);
m_process->m_signal_pending_mask &= ~(1ull << signal);
if (m_signal_suspend_mask.has_value())
{
@@ -661,7 +679,21 @@ namespace Kernel
m_signal_suspend_mask.clear();
}
m_signal_lock.unlock(state);
return {
.signal_handler = signal_handler,
.signal_stack_top = signal_stack_top,
.has_sa_restart = has_sa_restart,
};
}
void Thread::handle_signal_impl(int signal, const siginfo_t& signal_info, vaddr_t signal_handler, vaddr_t signal_stack_top)
{
ASSERT(this == &Thread::current());
ASSERT(is_userspace());
ASSERT(Processor::get_interrupt_state() == InterruptState::Enabled);
auto& interrupt_stack = *reinterpret_cast<InterruptStack*>(kernel_stack_top() - sizeof(InterruptStack));
ASSERT(GDT::is_user_segment(interrupt_stack.cs));
if (signal_handler == (vaddr_t)SIG_IGN)
;
@@ -696,10 +728,8 @@ namespace Kernel
{
if (m_process->page_table().get_page_flags(pages[i]) & PageTable::Flags::Present)
continue;
Processor::set_interrupt_state(InterruptState::Enabled);
if (auto ret = m_process->allocate_page_for_demand_paging(pages[i], true, false); ret.is_error() || !ret.value())
m_process->exit(128 + SIGSEGV, SIGSEGV);
Processor::set_interrupt_state(InterruptState::Disabled);
}
}
@@ -711,11 +741,13 @@ namespace Kernel
write_to_stack(interrupt_stack.sp, interrupt_stack.flags);
{
signal_info.si_signo = signal;
signal_info.si_addr = reinterpret_cast<void*>(interrupt_stack.ip);
interrupt_stack.sp -= sizeof(siginfo_t);
*reinterpret_cast<siginfo_t*>(interrupt_stack.sp) = signal_info;
auto& stack_signal_info = *reinterpret_cast<siginfo_t*>(interrupt_stack.sp);
stack_signal_info = signal_info;
stack_signal_info.si_signo = signal;
stack_signal_info.si_addr = reinterpret_cast<void*>(interrupt_stack.ip);
static_assert(sizeof(siginfo_t) % sizeof(uintptr_t) == 0);
}
@@ -752,8 +784,6 @@ namespace Kernel
panic("Executing unhandled signal {}", signal);
}
}
return has_sa_restart;
}
void Thread::add_signal(int signal, const siginfo_t& info)