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Kernel: Properly keep track of mutex lock data in the guest memory. This fixes userland locking/unlocking.

This commit is contained in:
Subv 2018-01-08 14:12:03 -05:00 committed by bunnei
parent 2a3f8e8484
commit 1bbe9309da
4 changed files with 63 additions and 67 deletions

View file

@ -257,10 +257,9 @@ std::vector<std::unique_ptr<WaitTreeItem>> WaitTreeMutex::GetChildren() const {
std::vector<std::unique_ptr<WaitTreeItem>> list(WaitTreeWaitObject::GetChildren());
const auto& mutex = static_cast<const Kernel::Mutex&>(object);
if (mutex.lock_count) {
list.push_back(
std::make_unique<WaitTreeText>(tr("locked %1 times by thread:").arg(mutex.lock_count)));
list.push_back(std::make_unique<WaitTreeThread>(*mutex.holding_thread));
if (mutex.GetHasWaiters()) {
list.push_back(std::make_unique<WaitTreeText>(tr("locked by thread:")));
list.push_back(std::make_unique<WaitTreeThread>(*mutex.GetHoldingThread()));
} else {
list.push_back(std::make_unique<WaitTreeText>(tr("free")));
}

View file

@ -17,8 +17,8 @@ namespace Kernel {
void ReleaseThreadMutexes(Thread* thread) {
for (auto& mtx : thread->held_mutexes) {
mtx->lock_count = 0;
mtx->holding_thread = nullptr;
mtx->SetHasWaiters(false);
mtx->SetHoldingThread(nullptr);
mtx->WakeupAllWaitingThreads();
}
thread->held_mutexes.clear();
@ -31,10 +31,8 @@ SharedPtr<Mutex> Mutex::Create(SharedPtr<Kernel::Thread> holding_thread, VAddr g
std::string name) {
SharedPtr<Mutex> mutex(new Mutex);
mutex->lock_count = 0;
mutex->guest_addr = guest_addr;
mutex->name = std::move(name);
mutex->holding_thread = nullptr;
// If mutex was initialized with a holding thread, acquire it by the holding thread
if (holding_thread) {
@ -51,56 +49,32 @@ SharedPtr<Mutex> Mutex::Create(SharedPtr<Kernel::Thread> holding_thread, VAddr g
}
bool Mutex::ShouldWait(Thread* thread) const {
return lock_count > 0 && thread != holding_thread;
auto holding_thread = GetHoldingThread();
return holding_thread != nullptr && thread != holding_thread;
}
void Mutex::Acquire(Thread* thread) {
ASSERT_MSG(!ShouldWait(thread), "object unavailable!");
// Actually "acquire" the mutex only if we don't already have it
if (lock_count == 0) {
priority = thread->current_priority;
thread->held_mutexes.insert(this);
holding_thread = thread;
thread->UpdatePriority();
UpdateGuestState();
Core::System::GetInstance().PrepareReschedule();
}
lock_count++;
priority = thread->current_priority;
thread->held_mutexes.insert(this);
SetHoldingThread(thread);
thread->UpdatePriority();
Core::System::GetInstance().PrepareReschedule();
}
ResultCode Mutex::Release(Thread* thread) {
auto holding_thread = GetHoldingThread();
ASSERT(holding_thread);
// We can only release the mutex if it's held by the calling thread.
if (thread != holding_thread) {
if (holding_thread) {
LOG_ERROR(
Kernel,
"Tried to release a mutex (owned by thread id %u) from a different thread id %u",
holding_thread->thread_id, thread->thread_id);
}
// TODO(bunnei): Use correct error code
return ResultCode(-1);
}
ASSERT(thread == holding_thread);
// Note: It should not be possible for the situation where the mutex has a holding thread with a
// zero lock count to occur. The real kernel still checks for this, so we do too.
if (lock_count <= 0) {
// TODO(bunnei): Use correct error code
return ResultCode(-1);
}
lock_count--;
// Yield to the next thread only if we've fully released the mutex
if (lock_count == 0) {
holding_thread->held_mutexes.erase(this);
holding_thread->UpdatePriority();
holding_thread = nullptr;
WakeupAllWaitingThreads();
UpdateGuestState();
Core::System::GetInstance().PrepareReschedule();
}
holding_thread->held_mutexes.erase(this);
holding_thread->UpdatePriority();
SetHoldingThread(nullptr);
WakeupAllWaitingThreads();
Core::System::GetInstance().PrepareReschedule();
return RESULT_SUCCESS;
}
@ -108,19 +82,20 @@ ResultCode Mutex::Release(Thread* thread) {
void Mutex::AddWaitingThread(SharedPtr<Thread> thread) {
WaitObject::AddWaitingThread(thread);
thread->pending_mutexes.insert(this);
SetHasWaiters(true);
UpdatePriority();
UpdateGuestState();
}
void Mutex::RemoveWaitingThread(Thread* thread) {
WaitObject::RemoveWaitingThread(thread);
thread->pending_mutexes.erase(this);
if (!GetHasWaiters())
SetHasWaiters(!GetWaitingThreads().empty());
UpdatePriority();
UpdateGuestState();
}
void Mutex::UpdatePriority() {
if (!holding_thread)
if (!GetHoldingThread())
return;
u32 best_priority = THREADPRIO_LOWEST;
@ -131,21 +106,35 @@ void Mutex::UpdatePriority() {
if (best_priority != priority) {
priority = best_priority;
holding_thread->UpdatePriority();
GetHoldingThread()->UpdatePriority();
}
}
void Mutex::UpdateGuestState() {
Handle Mutex::GetOwnerHandle() const {
GuestState guest_state{Memory::Read32(guest_addr)};
guest_state.has_waiters.Assign(!GetWaitingThreads().empty());
guest_state.holding_thread_handle.Assign(holding_thread ? holding_thread->guest_handle : 0);
return guest_state.holding_thread_handle;
}
SharedPtr<Thread> Mutex::GetHoldingThread() const {
GuestState guest_state{Memory::Read32(guest_addr)};
return g_handle_table.Get<Thread>(guest_state.holding_thread_handle);
}
void Mutex::SetHoldingThread(SharedPtr<Thread> thread) {
GuestState guest_state{Memory::Read32(guest_addr)};
guest_state.holding_thread_handle.Assign(thread ? thread->guest_handle : 0);
Memory::Write32(guest_addr, guest_state.raw);
}
void Mutex::VerifyGuestState() {
bool Mutex::GetHasWaiters() const {
GuestState guest_state{Memory::Read32(guest_addr)};
ASSERT(guest_state.has_waiters == !GetWaitingThreads().empty());
ASSERT(guest_state.holding_thread_handle == holding_thread->guest_handle);
return guest_state.has_waiters != 0;
}
void Mutex::SetHasWaiters(bool has_waiters) {
GuestState guest_state{Memory::Read32(guest_addr)};
guest_state.has_waiters.Assign(has_waiters ? 1 : 0);
Memory::Write32(guest_addr, guest_state.raw);
}
} // namespace Kernel

View file

@ -41,10 +41,8 @@ public:
return HANDLE_TYPE;
}
int lock_count; ///< Number of times the mutex has been acquired
u32 priority; ///< The priority of the mutex, used for priority inheritance.
std::string name; ///< Name of mutex (optional)
SharedPtr<Thread> holding_thread; ///< Thread that has acquired the mutex
VAddr guest_addr; ///< Address of the guest mutex value
/**
@ -66,6 +64,19 @@ public:
*/
ResultCode Release(Thread* thread);
/// Gets the handle to the holding process stored in the guest state.
Handle GetOwnerHandle() const;
/// Gets the Thread pointed to by the owner handle
SharedPtr<Thread> GetHoldingThread() const;
/// Sets the holding process handle in the guest state.
void SetHoldingThread(SharedPtr<Thread> thread);
/// Returns the has_waiters bit in the guest state.
bool GetHasWaiters() const;
/// Sets the has_waiters bit in the guest state.
void SetHasWaiters(bool has_waiters);
private:
Mutex();
~Mutex() override;
@ -79,12 +90,6 @@ private:
BitField<30, 1, u32_le> has_waiters;
};
static_assert(sizeof(GuestState) == 4, "GuestState size is incorrect");
/// Updates the state of the object tracking this mutex in guest memory
void UpdateGuestState();
/// Verifies the state of the object tracking this mutex in guest memory
void VerifyGuestState();
};
/**

View file

@ -204,7 +204,6 @@ static ResultCode LockMutex(Handle holding_thread_handle, VAddr mutex_addr,
SharedPtr<Thread> holding_thread = g_handle_table.Get<Thread>(holding_thread_handle);
SharedPtr<Thread> requesting_thread = g_handle_table.Get<Thread>(requesting_thread_handle);
ASSERT(holding_thread);
ASSERT(requesting_thread);
SharedPtr<Mutex> mutex = g_object_address_table.Get<Mutex>(mutex_addr);
@ -214,6 +213,8 @@ static ResultCode LockMutex(Handle holding_thread_handle, VAddr mutex_addr,
mutex->name = Common::StringFromFormat("mutex-%llx", mutex_addr);
}
ASSERT(holding_thread == mutex->GetHoldingThread());
return WaitSynchronization1(mutex, requesting_thread.get());
}
@ -491,6 +492,8 @@ static ResultCode WaitProcessWideKeyAtomic(VAddr mutex_addr, VAddr semaphore_add
mutex->name = Common::StringFromFormat("mutex-%llx", mutex_addr);
}
ASSERT(mutex->GetOwnerHandle() == thread_handle);
SharedPtr<Semaphore> semaphore = g_object_address_table.Get<Semaphore>(semaphore_addr);
if (!semaphore) {
// Create a new semaphore for the specified address if one does not already exist