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ladybird/Kernel/Thread.cpp
Andreas Kling 40beb4c5c0 Kernel: Don't leak an FPU state buffer for every spawned thread 
We were leaking 512 bytes of kmalloc memory for every new thread.
This patch fixes that, and also makes sure to zero out the FPU state
buffer after allocating it, and finally also makes the LogStream
operator<< for Thread look a little bit nicer. :^)
2019-10-13 14:36:55 +02:00

665 lines
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#include <AK/ELF/ELFLoader.h>
#include <AK/StringBuilder.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Thread.h>
#include <Kernel/VM/MemoryManager.h>
#include <LibC/signal_numbers.h>
//#define SIGNAL_DEBUG
u16 thread_specific_selector()
{
static u16 selector;
if (!selector) {
selector = gdt_alloc_entry();
auto& descriptor = get_gdt_entry(selector);
descriptor.dpl = 3;
descriptor.segment_present = 1;
descriptor.granularity = 0;
descriptor.zero = 0;
descriptor.operation_size = 1;
descriptor.descriptor_type = 1;
descriptor.type = 2;
}
return selector;
}
Descriptor& thread_specific_descriptor()
{
return get_gdt_entry(thread_specific_selector());
}
HashTable<Thread*>& thread_table()
{
ASSERT_INTERRUPTS_DISABLED();
static HashTable<Thread*>* table;
if (!table)
table = new HashTable<Thread*>;
return *table;
}
static const u32 default_kernel_stack_size = 65536;
static const u32 default_userspace_stack_size = 65536;
Thread::Thread(Process& process)
: m_process(process)
, m_tid(process.m_next_tid++)
{
dbgprintf("Thread{%p}: New thread TID=%u in %s(%u)\n", this, m_tid, process.name().characters(), process.pid());
set_default_signal_dispositions();
m_fpu_state = (FPUState*)kmalloc_aligned(sizeof(FPUState), 16);
memset(m_fpu_state, 0, sizeof(FPUState));
memset(&m_tss, 0, sizeof(m_tss));
// Only IF is set when a process boots.
m_tss.eflags = 0x0202;
u16 cs, ds, ss, gs;
if (m_process.is_ring0()) {
cs = 0x08;
ds = 0x10;
ss = 0x10;
gs = 0;
} else {
cs = 0x1b;
ds = 0x23;
ss = 0x23;
gs = thread_specific_selector() | 3;
}
m_tss.ds = ds;
m_tss.es = ds;
m_tss.fs = ds;
m_tss.gs = gs;
m_tss.ss = ss;
m_tss.cs = cs;
m_tss.cr3 = m_process.page_directory().cr3();
if (m_process.is_ring0()) {
// FIXME: This memory is leaked.
// But uh, there's also no kernel process termination, so I guess it's not technically leaked...
m_kernel_stack_base = (u32)kmalloc_eternal(default_kernel_stack_size);
m_kernel_stack_top = (m_kernel_stack_base + default_kernel_stack_size) & 0xfffffff8u;
m_tss.esp = m_kernel_stack_top;
} else {
// Ring3 processes need a separate stack for Ring0.
m_kernel_stack_region = MM.allocate_kernel_region(default_kernel_stack_size, String::format("Kernel Stack (Thread %d)", m_tid));
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;
m_tss.ss0 = 0x10;
m_tss.esp0 = m_kernel_stack_top;
}
// HACK: Ring2 SS in the TSS is the current PID.
m_tss.ss2 = m_process.pid();
m_far_ptr.offset = 0x98765432;
if (m_process.pid() != 0) {
InterruptDisabler disabler;
thread_table().set(this);
Scheduler::init_thread(*this);
}
}
Thread::~Thread()
{
dbgprintf("~Thread{%p}\n", this);
kfree_aligned(m_fpu_state);
{
InterruptDisabler disabler;
thread_table().remove(this);
}
if (g_last_fpu_thread == this)
g_last_fpu_thread = nullptr;
if (selector())
gdt_free_entry(selector());
if (m_userspace_stack_region)
m_process.deallocate_region(*m_userspace_stack_region);
}
void Thread::unblock()
{
if (current == this) {
set_state(Thread::Running);
return;
}
ASSERT(m_state != Thread::Runnable && m_state != Thread::Running);
set_state(Thread::Runnable);
}
void Thread::block_helper()
{
// This function mostly exists to avoid circular header dependencies. If
// anything needs adding, think carefully about whether it belongs in
// block() instead. Remember that we're unlocking here, so be very careful
// about altering any state once we're unlocked!
bool did_unlock = process().big_lock().unlock_if_locked();
Scheduler::yield();
if (did_unlock)
process().big_lock().lock();
}
u64 Thread::sleep(u32 ticks)
{
ASSERT(state() == Thread::Running);
u64 wakeup_time = g_uptime + ticks;
auto ret = current->block<Thread::SleepBlocker>(wakeup_time);
if (wakeup_time > g_uptime) {
ASSERT(ret == Thread::BlockResult::InterruptedBySignal);
}
return wakeup_time;
}
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::Skip1SchedulerPass:
return "Skip1";
case Thread::Skip0SchedulerPasses:
return "Skip0";
case Thread::Blocked:
ASSERT(m_blocker != nullptr);
return m_blocker->state_string();
}
kprintf("Thread::state_string(): Invalid state: %u\n", state());
ASSERT_NOT_REACHED();
return nullptr;
}
void Thread::finalize()
{
ASSERT(current == g_finalizer);
dbgprintf("Finalizing Thread %u in %s(%u)\n", tid(), m_process.name().characters(), pid());
set_state(Thread::State::Dead);
if (m_dump_backtrace_on_finalization)
dbg() << backtrace_impl();
if (this == &m_process.main_thread()) {
m_process.finalize();
return;
}
delete this;
}
void Thread::finalize_dying_threads()
{
ASSERT(current == g_finalizer);
Vector<Thread*, 32> dying_threads;
{
InterruptDisabler disabler;
for_each_in_state(Thread::State::Dying, [&](Thread& thread) {
dying_threads.append(&thread);
return IterationDecision::Continue;
});
}
for (auto* thread : dying_threads)
thread->finalize();
}
bool Thread::tick()
{
++m_ticks;
if (tss().cs & 3)
++m_process.m_ticks_in_user;
else
++m_process.m_ticks_in_kernel;
return --m_ticks_left;
}
void Thread::send_signal(u8 signal, Process* sender)
{
ASSERT(signal < 32);
InterruptDisabler disabler;
// FIXME: Figure out what to do for masked signals. Should we also ignore them here?
if (should_ignore_signal(signal)) {
dbg() << "signal " << signal << " was ignored by " << process();
return;
}
if (sender)
dbgprintf("signal: %s(%u) sent %d to %s(%u)\n", sender->name().characters(), sender->pid(), signal, process().name().characters(), pid());
else
dbgprintf("signal: kernel sent %d to %s(%u)\n", signal, process().name().characters(), pid());
m_pending_signals |= 1 << (signal - 1);
}
// 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)
{
// FIXME: because of a bug in dispatch_signal we can't
// setup a signal while we are the current thread. Because of
// this we use a work-around where we send the signal and then
// block, allowing the scheduler to properly dispatch the signal
// before the thread is next run.
send_signal(signal, &process());
(void)block<SemiPermanentBlocker>(SemiPermanentBlocker::Reason::Signal);
}
bool Thread::has_unmasked_pending_signals() const
{
return m_pending_signals & ~m_signal_mask;
}
ShouldUnblockThread Thread::dispatch_one_pending_signal()
{
ASSERT_INTERRUPTS_DISABLED();
u32 signal_candidates = m_pending_signals & ~m_signal_mask;
ASSERT(signal_candidates);
u8 signal = 1;
for (; signal < 32; ++signal) {
if (signal_candidates & (1 << (signal - 1))) {
break;
}
}
return dispatch_signal(signal);
}
enum class DefaultSignalAction {
Terminate,
Ignore,
DumpCore,
Stop,
Continue,
};
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:
case SIGPWR:
return DefaultSignalAction::Terminate;
case SIGCHLD:
case SIGURG:
case SIGWINCH:
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();
}
ShouldUnblockThread Thread::dispatch_signal(u8 signal)
{
ASSERT_INTERRUPTS_DISABLED();
ASSERT(signal > 0 && signal <= 32);
ASSERT(!process().is_ring0());
#ifdef SIGNAL_DEBUG
kprintf("dispatch_signal %s(%u) <- %u\n", process().name().characters(), pid(), signal);
#endif
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));
if (signal == SIGSTOP) {
set_state(Stopped);
return ShouldUnblockThread::No;
}
if (signal == SIGCONT && state() == Stopped)
set_state(Runnable);
auto handler_vaddr = action.handler_or_sigaction;
if (handler_vaddr.is_null()) {
switch (default_signal_action(signal)) {
case DefaultSignalAction::Stop:
set_state(Stopped);
return ShouldUnblockThread::No;
case DefaultSignalAction::DumpCore:
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 ShouldUnblockThread::No;
case DefaultSignalAction::Ignore:
ASSERT_NOT_REACHED();
case DefaultSignalAction::Continue:
return ShouldUnblockThread::Yes;
}
ASSERT_NOT_REACHED();
}
if (handler_vaddr.as_ptr() == SIG_IGN) {
#ifdef SIGNAL_DEBUG
kprintf("%s(%u) ignored signal %u\n", process().name().characters(), pid(), signal);
#endif
return ShouldUnblockThread::Yes;
}
ProcessPagingScope paging_scope(m_process);
// The userspace registers should be stored at the top of the stack
// We have to subtract 2 because the processor decrements the kernel
// stack before pushing the args.
auto& regs = *(RegisterDump*)(kernel_stack_top() - sizeof(RegisterDump) - 2);
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;
u32 old_esp = regs.esp_if_crossRing;
u32 ret_eip = regs.eip;
u32 ret_eflags = regs.eflags;
// 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 = (regs.esp_if_crossRing - 56) % 16;
regs.esp_if_crossRing -= stack_alignment;
push_value_on_user_stack(regs, ret_eflags);
push_value_on_user_stack(regs, ret_eip);
push_value_on_user_stack(regs, regs.eax);
push_value_on_user_stack(regs, regs.ecx);
push_value_on_user_stack(regs, regs.edx);
push_value_on_user_stack(regs, regs.ebx);
push_value_on_user_stack(regs, old_esp);
push_value_on_user_stack(regs, regs.ebp);
push_value_on_user_stack(regs, regs.esi);
push_value_on_user_stack(regs, regs.edi);
// PUSH old_signal_mask
push_value_on_user_stack(regs, old_signal_mask);
push_value_on_user_stack(regs, signal);
push_value_on_user_stack(regs, handler_vaddr.get());
push_value_on_user_stack(regs, 0); //push fake return address
regs.eip = g_return_to_ring3_from_signal_trampoline.get();
ASSERT((regs.esp_if_crossRing % 16) == 0);
// If we're not blocking we need to update the tss so
// that the far jump in Scheduler goes to the proper location.
// When we are blocking we don't update the TSS as we want to
// resume at the blocker and descend the stack, cleaning up nicely.
if (!in_kernel()) {
Scheduler::prepare_to_modify_tss(*this);
m_tss.cs = 0x1b;
m_tss.ds = 0x23;
m_tss.es = 0x23;
m_tss.fs = 0x23;
m_tss.gs = thread_specific_selector() | 3;
m_tss.eip = regs.eip;
m_tss.esp = regs.esp_if_crossRing;
// FIXME: This state is such a hack. It avoids trouble if 'current' is the process receiving a signal.
set_state(Skip1SchedulerPass);
}
#ifdef SIGNAL_DEBUG
kprintf("signal: Okay, %s(%u) {%s} has been primed with signal handler %w:%x\n", process().name().characters(), pid(), state_string(), m_tss.cs, m_tss.eip);
#endif
return ShouldUnblockThread::Yes;
}
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((u32)SIG_IGN);
m_signal_action_data[SIGWINCH].handler_or_sigaction = VirtualAddress((u32)SIG_IGN);
}
void Thread::push_value_on_user_stack(RegisterDump& registers, u32 value)
{
registers.esp_if_crossRing -= 4;
u32* stack_ptr = (u32*)registers.esp_if_crossRing;
*stack_ptr = value;
}
void Thread::push_value_on_stack(u32 value)
{
m_tss.esp -= 4;
u32* stack_ptr = (u32*)m_tss.esp;
*stack_ptr = value;
}
void Thread::make_userspace_stack_for_main_thread(Vector<String> arguments, Vector<String> environment)
{
auto* region = m_process.allocate_region(VirtualAddress(), default_userspace_stack_size, "Stack (Main thread)");
ASSERT(region);
m_tss.esp = region->vaddr().offset(default_userspace_stack_size).get();
char* stack_base = (char*)region->vaddr().get();
int argc = arguments.size();
char** argv = (char**)stack_base;
char** env = argv + arguments.size() + 1;
char* bufptr = stack_base + (sizeof(char*) * (arguments.size() + 1)) + (sizeof(char*) * (environment.size() + 1));
size_t total_blob_size = 0;
for (auto& a : arguments)
total_blob_size += a.length() + 1;
for (auto& e : environment)
total_blob_size += e.length() + 1;
size_t total_meta_size = sizeof(char*) * (arguments.size() + 1) + sizeof(char*) * (environment.size() + 1);
// FIXME: It would be better if this didn't make us panic.
ASSERT((total_blob_size + total_meta_size) < default_userspace_stack_size);
for (int i = 0; i < arguments.size(); ++i) {
argv[i] = bufptr;
memcpy(bufptr, arguments[i].characters(), arguments[i].length());
bufptr += arguments[i].length();
*(bufptr++) = '\0';
}
argv[arguments.size()] = nullptr;
for (int i = 0; i < environment.size(); ++i) {
env[i] = bufptr;
memcpy(bufptr, environment[i].characters(), environment[i].length());
bufptr += environment[i].length();
*(bufptr++) = '\0';
}
env[environment.size()] = nullptr;
// NOTE: The stack needs to be 16-byte aligned.
push_value_on_stack((u32)env);
push_value_on_stack((u32)argv);
push_value_on_stack((u32)argc);
push_value_on_stack(0);
}
void Thread::make_userspace_stack_for_secondary_thread(void* argument)
{
m_userspace_stack_region = m_process.allocate_region(VirtualAddress(), default_userspace_stack_size, String::format("Stack (Thread %d)", tid()));
ASSERT(m_userspace_stack_region);
m_tss.esp = m_userspace_stack_region->vaddr().offset(default_userspace_stack_size).get();
// NOTE: The stack needs to be 16-byte aligned.
push_value_on_stack((u32)argument);
push_value_on_stack(0);
}
Thread* Thread::clone(Process& process)
{
auto* clone = 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_has_used_fpu = m_has_used_fpu;
clone->m_thread_specific_data = m_thread_specific_data;
return clone;
}
void Thread::initialize()
{
Scheduler::initialize();
}
Vector<Thread*> Thread::all_threads()
{
Vector<Thread*> threads;
InterruptDisabler disabler;
threads.ensure_capacity(thread_table().size());
for (auto* thread : thread_table())
threads.unchecked_append(thread);
return threads;
}
bool Thread::is_thread(void* ptr)
{
ASSERT_INTERRUPTS_DISABLED();
return thread_table().contains((Thread*)ptr);
}
void Thread::set_state(State new_state)
{
InterruptDisabler disabler;
if (new_state == Blocked) {
// we should always have a Blocker while blocked
ASSERT(m_blocker != nullptr);
}
m_state = new_state;
if (m_process.pid() != 0) {
Scheduler::update_state_for_thread(*this);
}
}
String Thread::backtrace(ProcessInspectionHandle&) const
{
return backtrace_impl();
}
String Thread::backtrace_impl() const
{
auto& process = const_cast<Process&>(this->process());
ProcessPagingScope paging_scope(process);
struct RecognizedSymbol {
u32 address;
const KSym* ksym;
};
StringBuilder builder;
Vector<RecognizedSymbol, 64> recognized_symbols;
recognized_symbols.append({ tss().eip, ksymbolicate(tss().eip) });
for (u32* stack_ptr = (u32*)frame_ptr(); process.validate_read_from_kernel(VirtualAddress((u32)stack_ptr)); stack_ptr = (u32*)*stack_ptr) {
u32 retaddr = stack_ptr[1];
recognized_symbols.append({ retaddr, ksymbolicate(retaddr) });
}
for (auto& symbol : recognized_symbols) {
if (!symbol.address)
break;
if (!symbol.ksym) {
if (!Scheduler::is_active() && process.elf_loader() && process.elf_loader()->has_symbols())
builder.appendf("%p %s\n", symbol.address, process.elf_loader()->symbolicate(symbol.address).characters());
else
builder.appendf("%p\n", symbol.address);
continue;
}
unsigned offset = symbol.address - symbol.ksym->address;
if (symbol.ksym->address == ksym_highest_address && offset > 4096)
builder.appendf("%p\n", symbol.address);
else
builder.appendf("%p %s +%u\n", symbol.address, symbol.ksym->name, offset);
}
return builder.to_string();
}
void Thread::make_thread_specific_region(Badge<Process>)
{
size_t thread_specific_region_alignment = max(process().m_master_tls_alignment, alignof(ThreadSpecificData));
size_t thread_specific_region_size = align_up_to(process().m_master_tls_size, thread_specific_region_alignment) + sizeof(ThreadSpecificData);
auto* region = process().allocate_region({}, thread_specific_region_size, "Thread-specific", PROT_READ | PROT_WRITE, true);
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((u32)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->vaddr().as_ptr(), process().m_master_tls_size);
}
const LogStream& operator<<(const LogStream& stream, const Thread& value)
{
return stream << value.process().name() << "(" << value.pid() << ":" << value.tid() << ")";
}
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