// SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
#include "core/arm/exclusive_monitor.h"
#include "core/core.h"
#include "core/hle/kernel/k_condition_variable.h"
#include "core/hle/kernel/k_linked_list.h"
#include "core/hle/kernel/k_process.h"
#include "core/hle/kernel/k_scheduler.h"
#include "core/hle/kernel/k_scoped_scheduler_lock_and_sleep.h"
#include "core/hle/kernel/k_thread.h"
#include "core/hle/kernel/k_thread_queue.h"
#include "core/hle/kernel/kernel.h"
#include "core/hle/kernel/svc_common.h"
#include "core/hle/kernel/svc_results.h"
#include "core/memory.h"
namespace Kernel {
namespace {
bool ReadFromUser(Core::System& system, u32* out, VAddr address) {
*out = system.Memory().Read32(address);
return true;
}
bool WriteToUser(Core::System& system, VAddr address, const u32* p) {
system.Memory().Write32(address, *p);
return true;
}
bool UpdateLockAtomic(Core::System& system, u32* out, VAddr address, u32 if_zero,
u32 new_orr_mask) {
auto& monitor = system.Monitor();
const auto current_core = system.Kernel().CurrentPhysicalCoreIndex();
// Load the value from the address.
const auto expected = monitor.ExclusiveRead32(current_core, address);
// Orr in the new mask.
u32 value = expected | new_orr_mask;
// If the value is zero, use the if_zero value, otherwise use the newly orr'd value.
if (!expected) {
value = if_zero;
}
// Try to store.
if (!monitor.ExclusiveWrite32(current_core, address, value)) {
// If we failed to store, try again.
return UpdateLockAtomic(system, out, address, if_zero, new_orr_mask);
}
// We're done.
*out = expected;
return true;
}
class ThreadQueueImplForKConditionVariableWaitForAddress final : public KThreadQueue {
public:
explicit ThreadQueueImplForKConditionVariableWaitForAddress(KernelCore& kernel_)
: KThreadQueue(kernel_) {}
void CancelWait(KThread* waiting_thread, ResultCode wait_result,
bool cancel_timer_task) override {
// Remove the thread as a waiter from its owner.
waiting_thread->GetLockOwner()->RemoveWaiter(waiting_thread);
// Invoke the base cancel wait handler.
KThreadQueue::CancelWait(waiting_thread, wait_result, cancel_timer_task);
}
};
class ThreadQueueImplForKConditionVariableWaitConditionVariable final : public KThreadQueue {
private:
KConditionVariable::ThreadTree* m_tree;
public:
explicit ThreadQueueImplForKConditionVariableWaitConditionVariable(
KernelCore& kernel_, KConditionVariable::ThreadTree* t)
: KThreadQueue(kernel_), m_tree(t) {}
void CancelWait(KThread* waiting_thread, ResultCode wait_result,
bool cancel_timer_task) override {
// Remove the thread as a waiter from its owner.
if (KThread* owner = waiting_thread->GetLockOwner(); owner != nullptr) {
owner->RemoveWaiter(waiting_thread);
}
// If the thread is waiting on a condvar, remove it from the tree.
if (waiting_thread->IsWaitingForConditionVariable()) {
m_tree->erase(m_tree->iterator_to(*waiting_thread));
waiting_thread->ClearConditionVariable();
}
// Invoke the base cancel wait handler.
KThreadQueue::CancelWait(waiting_thread, wait_result, cancel_timer_task);
}
};
} // namespace
KConditionVariable::KConditionVariable(Core::System& system_)
: system{system_}, kernel{system.Kernel()} {}
KConditionVariable::~KConditionVariable() = default;
ResultCode KConditionVariable::SignalToAddress(VAddr addr) {
KThread* owner_thread = GetCurrentThreadPointer(kernel);
// Signal the address.
{
KScopedSchedulerLock sl(kernel);
// Remove waiter thread.
s32 num_waiters{};
KThread* next_owner_thread =
owner_thread->RemoveWaiterByKey(std::addressof(num_waiters), addr);
// Determine the next tag.
u32 next_value{};
if (next_owner_thread != nullptr) {
next_value = next_owner_thread->GetAddressKeyValue();
if (num_waiters > 1) {
next_value |= Svc::HandleWaitMask;
}
// Write the value to userspace.
ResultCode result{ResultSuccess};
if (WriteToUser(system, addr, std::addressof(next_value))) [[likely]] {
result = ResultSuccess;
} else {
result = ResultInvalidCurrentMemory;
}
// Signal the next owner thread.
next_owner_thread->EndWait(result);
return result;
} else {
// Just write the value to userspace.
R_UNLESS(WriteToUser(system, addr, std::addressof(next_value)),
ResultInvalidCurrentMemory);
return ResultSuccess;
}
}
}
ResultCode KConditionVariable::WaitForAddress(Handle handle, VAddr addr, u32 value) {
KThread* cur_thread = GetCurrentThreadPointer(kernel);
ThreadQueueImplForKConditionVariableWaitForAddress wait_queue(kernel);
// Wait for the address.
KThread* owner_thread{};
{
KScopedSchedulerLock sl(kernel);
// Check if the thread should terminate.
R_UNLESS(!cur_thread->IsTerminationRequested(), ResultTerminationRequested);
// Read the tag from userspace.
u32 test_tag{};
R_UNLESS(ReadFromUser(system, std::addressof(test_tag), addr), ResultInvalidCurrentMemory);
// If the tag isn't the handle (with wait mask), we're done.
R_SUCCEED_IF(test_tag != (handle | Svc::HandleWaitMask));
// Get the lock owner thread.
owner_thread = kernel.CurrentProcess()
->GetHandleTable()
.GetObjectWithoutPseudoHandle<KThread>(handle)
.ReleasePointerUnsafe();
R_UNLESS(owner_thread != nullptr, ResultInvalidHandle);
// Update the lock.
cur_thread->SetAddressKey(addr, value);
owner_thread->AddWaiter(cur_thread);
// Begin waiting.
cur_thread->BeginWait(std::addressof(wait_queue));
cur_thread->SetWaitReasonForDebugging(ThreadWaitReasonForDebugging::ConditionVar);
cur_thread->SetMutexWaitAddressForDebugging(addr);
}
// Close our reference to the owner thread, now that the wait is over.
owner_thread->Close();
// Get the wait result.
return cur_thread->GetWaitResult();
}
void KConditionVariable::SignalImpl(KThread* thread) {
// Check pre-conditions.
ASSERT(kernel.GlobalSchedulerContext().IsLocked());
// Update the tag.
VAddr address = thread->GetAddressKey();
u32 own_tag = thread->GetAddressKeyValue();
u32 prev_tag{};
bool can_access{};
{
// TODO(bunnei): We should disable interrupts here via KScopedInterruptDisable.
// TODO(bunnei): We should call CanAccessAtomic(..) here.
can_access = true;
if (can_access) [[likely]] {
UpdateLockAtomic(system, std::addressof(prev_tag), address, own_tag,
Svc::HandleWaitMask);
}
}
if (can_access) [[likely]] {
if (prev_tag == Svc::InvalidHandle) {
// If nobody held the lock previously, we're all good.
thread->EndWait(ResultSuccess);
} else {
// Get the previous owner.
KThread* owner_thread = kernel.CurrentProcess()
->GetHandleTable()
.GetObjectWithoutPseudoHandle<KThread>(
static_cast<Handle>(prev_tag & ~Svc::HandleWaitMask))
.ReleasePointerUnsafe();
if (owner_thread) [[likely]] {
// Add the thread as a waiter on the owner.
owner_thread->AddWaiter(thread);
owner_thread->Close();
} else {
// The lock was tagged with a thread that doesn't exist.
thread->EndWait(ResultInvalidState);
}
}
} else {
// If the address wasn't accessible, note so.
thread->EndWait(ResultInvalidCurrentMemory);
}
}
void KConditionVariable::Signal(u64 cv_key, s32 count) {
// Perform signaling.
s32 num_waiters{};
{
KScopedSchedulerLock sl(kernel);
auto it = thread_tree.nfind_key({cv_key, -1});
while ((it != thread_tree.end()) && (count <= 0 || num_waiters < count) &&
(it->GetConditionVariableKey() == cv_key)) {
KThread* target_thread = std::addressof(*it);
this->SignalImpl(target_thread);
it = thread_tree.erase(it);
target_thread->ClearConditionVariable();
++num_waiters;
}
// If we have no waiters, clear the has waiter flag.
if (it == thread_tree.end() || it->GetConditionVariableKey() != cv_key) {
const u32 has_waiter_flag{};
WriteToUser(system, cv_key, std::addressof(has_waiter_flag));
}
}
}
ResultCode KConditionVariable::Wait(VAddr addr, u64 key, u32 value, s64 timeout) {
// Prepare to wait.
KThread* cur_thread = GetCurrentThreadPointer(kernel);
ThreadQueueImplForKConditionVariableWaitConditionVariable wait_queue(
kernel, std::addressof(thread_tree));
{
KScopedSchedulerLockAndSleep slp(kernel, cur_thread, timeout);
// Check that the thread isn't terminating.
if (cur_thread->IsTerminationRequested()) {
slp.CancelSleep();
return ResultTerminationRequested;
}
// Update the value and process for the next owner.
{
// Remove waiter thread.
s32 num_waiters{};
KThread* next_owner_thread =
cur_thread->RemoveWaiterByKey(std::addressof(num_waiters), addr);
// Update for the next owner thread.
u32 next_value{};
if (next_owner_thread != nullptr) {
// Get the next tag value.
next_value = next_owner_thread->GetAddressKeyValue();
if (num_waiters > 1) {
next_value |= Svc::HandleWaitMask;
}
// Wake up the next owner.
next_owner_thread->EndWait(ResultSuccess);
}
// Write to the cv key.
{
const u32 has_waiter_flag = 1;
WriteToUser(system, key, std::addressof(has_waiter_flag));
// TODO(bunnei): We should call DataMemoryBarrier(..) here.
}
// Write the value to userspace.
if (!WriteToUser(system, addr, std::addressof(next_value))) {
slp.CancelSleep();
return ResultInvalidCurrentMemory;
}
}
// If timeout is zero, time out.
R_UNLESS(timeout != 0, ResultTimedOut);
// Update condition variable tracking.
cur_thread->SetConditionVariable(std::addressof(thread_tree), addr, key, value);
thread_tree.insert(*cur_thread);
// Begin waiting.
cur_thread->BeginWait(std::addressof(wait_queue));
cur_thread->SetWaitReasonForDebugging(ThreadWaitReasonForDebugging::ConditionVar);
cur_thread->SetMutexWaitAddressForDebugging(addr);
}
// Get the wait result.
return cur_thread->GetWaitResult();
}
} // namespace Kernel