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Kernel: Implement process stopping and continuing

This commit is contained in:
Bananymous 2025-08-31 00:34:52 +03:00
parent 56684e753b
commit 791a541381
6 changed files with 311 additions and 125 deletions
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16
kernel/include/kernel/Process.h
View File

@ -188,6 +188,9 @@ namespace Kernel
BAN::ErrorOr<long> sys_tty_ctrl(int fildes, int command, int flags);
void set_stopped(bool stopped, int signal);
void wait_while_stopped();
static BAN::ErrorOr<void> kill(pid_t pid, int signal);
BAN::ErrorOr<long> sys_kill(pid_t pid, int signal);
BAN::ErrorOr<long> sys_sigaction(int signal, const struct sigaction* act, struct sigaction* oact);
@ -299,12 +302,11 @@ namespace Kernel
}
private:
struct ChildExitStatus
struct ChildWaitStatus
{
pid_t pid { 0 };
pid_t pgrp { 0 };
int exit_code { 0 };
bool exited { false };
BAN::Optional<int> status;
};
Credentials m_credentials;
@ -320,6 +322,9 @@ namespace Kernel
mutable Mutex m_process_lock;
BAN::Atomic<bool> m_stopped { false };
ThreadBlocker m_stop_blocker;
VirtualFileSystem::File m_working_directory;
VirtualFileSystem::File m_root_file;
@ -344,8 +349,9 @@ namespace Kernel
BAN::Vector<BAN::String> m_environ;
BAN::String m_executable;
BAN::Vector<ChildExitStatus> m_child_exit_statuses;
ThreadBlocker m_child_exit_blocker;
BAN::Vector<ChildWaitStatus> m_child_wait_statuses;
SpinLock m_child_wait_lock;
ThreadBlocker m_child_wait_blocker;
BAN::Atomic<bool> m_is_exiting { false };

9
kernel/include/kernel/Thread.h
View File

@ -53,7 +53,7 @@ namespace Kernel
BAN::ErrorOr<void> initialize_userspace(vaddr_t entry, BAN::Span<BAN::String> argv, BAN::Span<BAN::String> envp, BAN::Span<LibELF::AuxiliaryVector> auxv);
// Returns true, if thread is going to trigger signal
bool is_interrupted_by_signal() const;
bool is_interrupted_by_signal(bool skip_stop_and_cont = false) const;
// Returns true if pending signal can be added to thread
bool can_add_signal_to_execute() const;
@ -63,6 +63,13 @@ namespace Kernel
void add_signal(int signal);
void set_suspend_signal_mask(uint64_t sigmask);
static bool is_stopping_signal(int signal);
static bool is_continuing_signal(int signal);
static bool is_terminating_signal(int signal);
static bool is_abnormal_terminating_signal(int signal);
static bool is_realtime_signal(int signal);
bool will_exit_because_of_signal() const;
BAN::ErrorOr<void> sigaltstack(const stack_t* ss, stack_t* oss);
// blocks current thread and returns either on unblock, eintr, spuriously or after timeout

180
kernel/kernel/Process.cpp
View File

@ -9,6 +9,7 @@
#include <kernel/IDT.h>
#include <kernel/InterruptController.h>
#include <kernel/Lock/LockGuard.h>
#include <kernel/Lock/SpinLockAsMutex.h>
#include <kernel/Memory/FileBackedRegion.h>
#include <kernel/Memory/Heap.h>
#include <kernel/Memory/MemoryBackedRegion.h>
@ -295,21 +296,20 @@ namespace Kernel
if (parent_process)
{
LockGuard _(parent_process->m_process_lock);
SpinLockGuard _(parent_process->m_child_wait_lock);
for (auto& child : parent_process->m_child_exit_statuses)
for (auto& child : parent_process->m_child_wait_statuses)
{
if (child.pid != pid())
continue;
child.exit_code = __WGENEXITCODE(status, signal);
child.exited = true;
child.status = __WGENEXITCODE(status, signal);
parent_process->add_pending_signal(SIGCHLD);
if (!parent_process->m_threads.empty())
Processor::scheduler().unblock_thread(parent_process->m_threads.front());
parent_process->m_child_exit_blocker.unblock();
parent_process->m_child_wait_blocker.unblock();
break;
}
@ -588,8 +588,11 @@ namespace Kernel
LockGuard _(m_process_lock);
ChildExitStatus* child_exit_status = nullptr;
for (auto& child : m_child_exit_statuses)
ChildWaitStatus* child_exit_status = nullptr;
{
SpinLockGuard _(m_child_wait_lock);
for (auto& child : m_child_wait_statuses)
{
if (child.pid != 0)
continue;
@ -598,8 +601,9 @@ namespace Kernel
}
if (child_exit_status == nullptr)
{
TRY(m_child_exit_statuses.emplace_back());
child_exit_status = &m_child_exit_statuses.back();
TRY(m_child_wait_statuses.emplace_back());
child_exit_status = &m_child_wait_statuses.back();
}
}
auto working_directory = TRY(m_working_directory.clone());
@ -794,7 +798,7 @@ namespace Kernel
// FIXME: Add WCONTINUED and WUNTRACED when stopped/continued processes are added
const auto pid_matches =
[&](const ChildExitStatus& child)
[&](const ChildWaitStatus& child)
{
if (pid == -1)
return true;
@ -805,47 +809,67 @@ namespace Kernel
return child.pid == pid;
};
LockGuard _(m_process_lock);
pid_t child_pid = 0;
int child_status = 0;
for (;;)
{
pid_t exited_pid = 0;
int exit_code = 0;
{
bool found = false;
for (auto& child : m_child_exit_statuses)
SpinLockGuard sguard(m_child_wait_lock);
for (auto& child : m_child_wait_statuses)
{
if (!pid_matches(child))
continue;
found = true;
if (!child.exited)
if (!child.status.has_value())
continue;
exited_pid = child.pid;
exit_code = child.exit_code;
child = {};
const int status = child.status.value();
bool should_report = false;
if (WIFSTOPPED(status))
should_report = !!(options & WUNTRACED);
else if (WIFCONTINUED(status))
should_report = !!(options & WCONTINUED);
else
should_report = true;
if (!should_report)
continue;
child_pid = child.pid;
child_status = status;
child.status = {};
break;
}
if (child_pid != 0)
break;
if (!found)
return BAN::Error::from_errno(ECHILD);
}
if (exited_pid != 0)
{
if (stat_loc)
{
TRY(validate_pointer_access(stat_loc, sizeof(stat_loc), true));
*stat_loc = exit_code;
}
remove_pending_signal(SIGCHLD);
return exited_pid;
}
if (options & WNOHANG)
return 0;
TRY(Thread::current().block_or_eintr_indefinite(m_child_exit_blocker, &m_process_lock));
SpinLockGuardAsMutex smutex(sguard);
TRY(Thread::current().block_or_eintr_indefinite(m_child_wait_blocker, &smutex));
}
LockGuard _(m_process_lock);
if (stat_loc)
{
TRY(validate_pointer_access(stat_loc, sizeof(stat_loc), true));
*stat_loc = child_status;
}
remove_pending_signal(SIGCHLD);
return child_pid;
}
BAN::ErrorOr<long> Process::sys_sleep(int seconds)
@ -2583,6 +2607,69 @@ namespace Kernel
return 0;
}
void Process::set_stopped(bool stopped, int signal)
{
SpinLockGuard _(m_signal_lock);
Process* parent = nullptr;
for_each_process(
[&parent, this](Process& process) -> BAN::Iteration
{
if (process.pid() != m_parent)
return BAN::Iteration::Continue;
parent = &process;
return BAN::Iteration::Break;
}
);
if (parent != nullptr)
{
{
SpinLockGuard _(parent->m_child_wait_lock);
for (auto& child : parent->m_child_wait_statuses)
{
if (child.pid != pid())
continue;
if (!child.status.has_value() || WIFCONTINUED(*child.status) || WIFSTOPPED(*child.status))
child.status = stopped
? __WGENSTOPCODE(signal)
: __WGENCONTCODE();
break;
}
parent->m_child_wait_blocker.unblock();
}
if (!(m_signal_handlers[SIGCHLD].sa_flags & SA_NOCLDSTOP))
{
parent->add_pending_signal(SIGCHLD);
if (!parent->m_threads.empty())
Processor::scheduler().unblock_thread(parent->m_threads.front());
}
}
m_stopped = stopped;
m_stop_blocker.unblock();
}
void Process::wait_while_stopped()
{
for (;;)
{
while (Thread::current().will_exit_because_of_signal())
Thread::current().handle_signal();
SpinLockGuard guard(m_signal_lock);
if (!m_stopped)
break;
SpinLockGuardAsMutex smutex(guard);
m_stop_blocker.block_indefinite(&smutex);
}
}
BAN::ErrorOr<void> Process::kill(pid_t pid, int signal)
{
if (pid == 0 || pid == -1)
@ -2594,19 +2681,27 @@ namespace Kernel
for_each_process(
[&](Process& process)
{
if (pid == process.pid() || -pid == process.pgrp())
{
if (pid != process.pid() && -pid != process.pgrp())
return BAN::Iteration::Continue;
found = true;
if (signal)
if (signal == 0)
;
// NOTE: stopped signals go through thread's signal handling code
// because for example SIGTSTP can be ignored
else if (Thread::is_continuing_signal(signal))
process.set_stopped(false, signal);
else
{
process.add_pending_signal(signal);
if (!process.m_threads.empty())
Processor::scheduler().unblock_thread(process.m_threads.front());
process.m_stop_blocker.unblock();
}
return (pid > 0) ? BAN::Iteration::Break : BAN::Iteration::Continue;
}
return BAN::Iteration::Continue;
}
);
if (found)
@ -2623,8 +2718,17 @@ namespace Kernel
if (pid == m_pid)
{
if (signal)
if (signal == 0)
;
// NOTE: stopped signals go through thread's signal handling code
// because for example SIGTSTP can be ignored
else if (Thread::is_continuing_signal(signal))
set_stopped(false, signal);
else
{
add_pending_signal(signal);
m_stop_blocker.unblock();
}
return 0;
}

4
kernel/kernel/Syscall.cpp
View File

@ -46,6 +46,8 @@ namespace Kernel
Processor::set_interrupt_state(InterruptState::Enabled);
Process::current().wait_while_stopped();
BAN::ErrorOr<long> ret = BAN::Error::from_errno(ENOSYS);
const char* process_path = Process::current().name();
@ -92,6 +94,8 @@ namespace Kernel
if (ret.is_error() && ret.error().is_kernel_error())
Kernel::panic("Kernel error while returning to userspace {}", ret.error());
Process::current().wait_while_stopped();
Processor::set_interrupt_state(InterruptState::Disabled);
auto& current_thread = Thread::current();

158
kernel/kernel/Thread.cpp
View File

@ -69,6 +69,77 @@ namespace Kernel
s_default_sse_storage_initialized = true;
}
bool Thread::is_stopping_signal(int signal)
{
switch(signal)
{
case SIGSTOP:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
return true;
default:
return false;
}
}
bool Thread::is_continuing_signal(int signal)
{
switch(signal)
{
case SIGCONT:
return true;
default:
return false;
}
}
bool Thread::is_terminating_signal(int signal)
{
switch (signal)
{
case SIGALRM:
case SIGHUP:
case SIGINT:
case SIGKILL:
case SIGPIPE:
case SIGTERM:
case SIGUSR1:
case SIGUSR2:
case SIGPOLL:
case SIGPROF:
case SIGVTALRM:
return true;
default:
return false;
}
}
bool Thread::is_abnormal_terminating_signal(int signal)
{
switch (signal)
{
case SIGABRT:
case SIGBUS:
case SIGFPE:
case SIGILL:
case SIGQUIT:
case SIGSEGV:
case SIGSYS:
case SIGTRAP:
case SIGXCPU:
case SIGXFSZ:
return true;
default:
return false;
}
}
bool Thread::is_realtime_signal(int signal)
{
return SIGRTMIN <= signal && signal <= SIGRTMAX;
}
static bool is_default_ignored_signal(int signal)
{
switch (signal)
@ -79,7 +150,7 @@ namespace Kernel
case SIGCANCEL:
return true;
default:
return false;
return Thread::is_realtime_signal(signal);
}
}
@ -458,7 +529,7 @@ namespace Kernel
memset(&m_interrupt_registers, 0, sizeof(InterruptRegisters));
}
bool Thread::is_interrupted_by_signal() const
bool Thread::is_interrupted_by_signal(bool skip_stop_and_cont) const
{
if (!is_userspace() || m_state != State::Executing)
return false;
@ -472,6 +543,8 @@ namespace Kernel
{
if (!(signals & ((uint64_t)1 << i)))
continue;
if (skip_stop_and_cont && (is_stopping_signal(i) || is_continuing_signal(i)))
continue;
vaddr_t signal_handler;
{
@ -501,13 +574,23 @@ namespace Kernel
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();
const uint64_t signals = full_pending_mask & ~m_signal_block_mask;
for (size_t sig = _SIGMIN; sig <= _SIGMAX; sig++)
if (signals & (static_cast<uint64_t>(1) << sig))
if (is_terminating_signal(sig) || is_abnormal_terminating_signal(sig))
return true;
return false;
}
bool Thread::handle_signal(int signal)
{
ASSERT(&Thread::current() == this);
ASSERT(is_userspace());
auto state = m_signal_lock.lock();
ASSERT(state == InterruptState::Disabled);
auto& interrupt_stack = *reinterpret_cast<InterruptStack*>(kernel_stack_top() - sizeof(InterruptStack));
ASSERT(GDT::is_user_segment(interrupt_stack.cs));
@ -613,51 +696,30 @@ namespace Kernel
}
else
{
switch (signal)
if (is_abnormal_terminating_signal(signal))
{
// Abnormal termination of the process with additional actions.
case SIGABRT:
case SIGBUS:
case SIGFPE:
case SIGILL:
case SIGQUIT:
case SIGSEGV:
case SIGSYS:
case SIGTRAP:
case SIGXCPU:
case SIGXFSZ:
process().exit(128 + signal, signal | 0x80);
ASSERT_NOT_REACHED();
// Abnormal termination of the process
case SIGALRM:
case SIGHUP:
case SIGINT:
case SIGKILL:
case SIGPIPE:
case SIGTERM:
case SIGUSR1:
case SIGUSR2:
case SIGPOLL:
case SIGPROF:
case SIGVTALRM:
}
else if (is_terminating_signal(signal))
{
process().exit(128 + signal, signal);
ASSERT_NOT_REACHED();
}
else if (is_stopping_signal(signal))
{
process().set_stopped(true, signal);
}
else if (is_continuing_signal(signal))
{
process().set_stopped(false, signal);
}
else if (is_default_ignored_signal(signal))
{
// Stop the process:
case SIGSTOP:
case SIGTSTP:
case SIGTTIN:
case SIGTTOU:
ASSERT_NOT_REACHED();
// Continue the process, if it is stopped; otherwise, ignore the signal.
case SIGCONT:
ASSERT_NOT_REACHED();
default:
if (is_default_ignored_signal(signal))
break;
}
else
{
panic("Executing unhandled signal {}", signal);
}
}
@ -739,20 +801,20 @@ namespace Kernel
BAN::ErrorOr<void> Thread::sleep_or_eintr_ns(uint64_t ns)
{
if (is_interrupted_by_signal())
if (is_interrupted_by_signal(true))
return BAN::Error::from_errno(EINTR);
SystemTimer::get().sleep_ns(ns);
if (is_interrupted_by_signal())
if (is_interrupted_by_signal(true))
return BAN::Error::from_errno(EINTR);
return {};
}
BAN::ErrorOr<void> Thread::block_or_eintr_indefinite(ThreadBlocker& thread_blocker, BaseMutex* mutex)
{
if (is_interrupted_by_signal())
if (is_interrupted_by_signal(true))
return BAN::Error::from_errno(EINTR);
thread_blocker.block_indefinite(mutex);
if (is_interrupted_by_signal())
if (is_interrupted_by_signal(true))
return BAN::Error::from_errno(EINTR);
return {};
}
@ -765,10 +827,10 @@ namespace Kernel
BAN::ErrorOr<void> Thread::block_or_eintr_or_waketime_ns(ThreadBlocker& thread_blocker, uint64_t wake_time_ns, bool etimedout, BaseMutex* mutex)
{
if (is_interrupted_by_signal())
if (is_interrupted_by_signal(true))
return BAN::Error::from_errno(EINTR);
thread_blocker.block_with_wake_time_ns(wake_time_ns, mutex);
if (is_interrupted_by_signal())
if (is_interrupted_by_signal(true))
return BAN::Error::from_errno(EINTR);
if (etimedout && SystemTimer::get().ms_since_boot() >= wake_time_ns)
return BAN::Error::from_errno(ETIMEDOUT);

7
userspace/libraries/LibC/include/sys/wait.h
View File

@ -24,10 +24,13 @@ __BEGIN_DECLS
#define WSTOPSIG(status) WEXITSTATUS(status)
#define WTERMSIG(status) ((status) & 0x7F)
#define WIFEXITED(status) (WTERMSIG(status) == 0)
#define WIFSIGNALED(status) (((status) & 0x7F) > 0 && ((status) & 0x7F) < 0x7F)
#define WIFSTOPPED(status) (((status) & 0xFF) == 0x7F)
#define WIFSIGNALED(status) (((status) & 0x7F) > 0 && ((status) & 0x7F) < 0x7E)
#define WIFSTOPPED(status) (((status) & 0x7F) == 0x7F)
#define WIFCONTINUED(status) (((status) & 0x7F) == 0x7E)
#define __WGENEXITCODE(ret, sig) (((ret) << 8) | (sig))
#define __WGENSTOPCODE(sig) (((sig) << 8) | 0x7F)
#define __WGENCONTCODE() ( 0x7E)
typedef enum
{