baed7e1fba
Many of the member variables of the thread class aren't even used outside of the class itself, so there's no need to make those variables public. This change follows in the steps of the previous changes that made other kernel types' members private. The main motivation behind this is that the Thread class will likely change in the future as emulation becomes more accurate, and letting random bits of the emulator access data members of the Thread class directly makes it a pain to shuffle around and/or modify internals. Having all data members public like this also makes it difficult to reason about certain bits of behavior without first verifying what parts of the core actually use them. Everything being public also generally follows the tendency for changes to be introduced in completely different translation units that would otherwise be better introduced as an addition to the Thread class' public interface.
138 lines
4.5 KiB
C++
138 lines
4.5 KiB
C++
// Copyright 2014 Citra Emulator Project
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// Licensed under GPLv2 or any later version
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// Refer to the license.txt file included.
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#include <map>
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#include <utility>
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#include <vector>
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#include <boost/range/algorithm_ext/erase.hpp>
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#include "common/assert.h"
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#include "core/core.h"
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#include "core/hle/kernel/errors.h"
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#include "core/hle/kernel/handle_table.h"
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#include "core/hle/kernel/mutex.h"
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#include "core/hle/kernel/object.h"
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#include "core/hle/kernel/thread.h"
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#include "core/hle/result.h"
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#include "core/memory.h"
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namespace Kernel {
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/// Returns the number of threads that are waiting for a mutex, and the highest priority one among
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/// those.
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static std::pair<SharedPtr<Thread>, u32> GetHighestPriorityMutexWaitingThread(
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const SharedPtr<Thread>& current_thread, VAddr mutex_addr) {
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SharedPtr<Thread> highest_priority_thread;
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u32 num_waiters = 0;
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for (const auto& thread : current_thread->GetMutexWaitingThreads()) {
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if (thread->GetMutexWaitAddress() != mutex_addr)
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continue;
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ASSERT(thread->GetStatus() == ThreadStatus::WaitMutex);
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++num_waiters;
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if (highest_priority_thread == nullptr ||
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thread->GetPriority() < highest_priority_thread->GetPriority()) {
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highest_priority_thread = thread;
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}
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}
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return {highest_priority_thread, num_waiters};
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}
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/// Update the mutex owner field of all threads waiting on the mutex to point to the new owner.
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static void TransferMutexOwnership(VAddr mutex_addr, SharedPtr<Thread> current_thread,
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SharedPtr<Thread> new_owner) {
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const auto& threads = current_thread->GetMutexWaitingThreads();
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for (const auto& thread : threads) {
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if (thread->GetMutexWaitAddress() != mutex_addr)
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continue;
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ASSERT(thread->GetLockOwner() == current_thread);
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current_thread->RemoveMutexWaiter(thread);
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if (new_owner != thread)
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new_owner->AddMutexWaiter(thread);
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}
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}
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ResultCode Mutex::TryAcquire(HandleTable& handle_table, VAddr address, Handle holding_thread_handle,
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Handle requesting_thread_handle) {
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// The mutex address must be 4-byte aligned
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if ((address % sizeof(u32)) != 0) {
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return ERR_INVALID_ADDRESS;
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}
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SharedPtr<Thread> holding_thread = handle_table.Get<Thread>(holding_thread_handle);
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SharedPtr<Thread> requesting_thread = handle_table.Get<Thread>(requesting_thread_handle);
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// TODO(Subv): It is currently unknown if it is possible to lock a mutex in behalf of another
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// thread.
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ASSERT(requesting_thread == GetCurrentThread());
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u32 addr_value = Memory::Read32(address);
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// If the mutex isn't being held, just return success.
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if (addr_value != (holding_thread_handle | Mutex::MutexHasWaitersFlag)) {
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return RESULT_SUCCESS;
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}
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if (holding_thread == nullptr)
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return ERR_INVALID_HANDLE;
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// Wait until the mutex is released
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GetCurrentThread()->SetMutexWaitAddress(address);
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GetCurrentThread()->SetWaitHandle(requesting_thread_handle);
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GetCurrentThread()->SetStatus(ThreadStatus::WaitMutex);
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GetCurrentThread()->InvalidateWakeupCallback();
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// Update the lock holder thread's priority to prevent priority inversion.
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holding_thread->AddMutexWaiter(GetCurrentThread());
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Core::System::GetInstance().PrepareReschedule();
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return RESULT_SUCCESS;
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}
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ResultCode Mutex::Release(VAddr address) {
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// The mutex address must be 4-byte aligned
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if ((address % sizeof(u32)) != 0) {
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return ERR_INVALID_ADDRESS;
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}
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auto [thread, num_waiters] = GetHighestPriorityMutexWaitingThread(GetCurrentThread(), address);
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// There are no more threads waiting for the mutex, release it completely.
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if (thread == nullptr) {
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Memory::Write32(address, 0);
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return RESULT_SUCCESS;
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}
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// Transfer the ownership of the mutex from the previous owner to the new one.
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TransferMutexOwnership(address, GetCurrentThread(), thread);
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u32 mutex_value = thread->GetWaitHandle();
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if (num_waiters >= 2) {
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// Notify the guest that there are still some threads waiting for the mutex
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mutex_value |= Mutex::MutexHasWaitersFlag;
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}
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// Grant the mutex to the next waiting thread and resume it.
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Memory::Write32(address, mutex_value);
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ASSERT(thread->GetStatus() == ThreadStatus::WaitMutex);
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thread->ResumeFromWait();
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thread->SetLockOwner(nullptr);
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thread->SetCondVarWaitAddress(0);
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thread->SetMutexWaitAddress(0);
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thread->SetWaitHandle(0);
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return RESULT_SUCCESS;
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}
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} // namespace Kernel
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