0cbcd6ec9a
As means to pave the way for getting rid of global state within core, This eliminates kernel global state by removing all globals. Instead this introduces a KernelCore class which acts as a kernel instance. This instance lives in the System class, which keeps its lifetime contained to the lifetime of the System class. This also forces the kernel types to actually interact with the main kernel instance itself instead of having transient kernel state placed all over several translation units, keeping everything together. It also has a nice consequence of making dependencies much more explicit. This also makes our initialization a tad bit more correct. Previously we were creating a kernel process before the actual kernel was initialized, which doesn't really make much sense. The KernelCore class itself follows the PImpl idiom, which allows keeping all the implementation details sealed away from everything else, which forces the use of the exposed API and allows us to avoid any unnecessary inclusions within the main kernel header.
137 lines
4.5 KiB
C++
137 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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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 (auto& thread : current_thread->wait_mutex_threads) {
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if (thread->mutex_wait_address != mutex_addr)
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continue;
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ASSERT(thread->status == 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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auto threads = current_thread->wait_mutex_threads;
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for (auto& thread : threads) {
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if (thread->mutex_wait_address != mutex_addr)
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continue;
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ASSERT(thread->lock_owner == 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 ResultCode(ErrorModule::Kernel, ErrCodes::InvalidAddress);
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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()->mutex_wait_address = address;
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GetCurrentThread()->wait_handle = requesting_thread_handle;
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GetCurrentThread()->status = ThreadStatus::WaitMutex;
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GetCurrentThread()->wakeup_callback = nullptr;
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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 ResultCode(ErrorModule::Kernel, ErrCodes::InvalidAddress);
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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->wait_handle;
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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->status == ThreadStatus::WaitMutex);
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thread->ResumeFromWait();
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thread->lock_owner = nullptr;
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thread->condvar_wait_address = 0;
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thread->mutex_wait_address = 0;
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thread->wait_handle = 0;
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return RESULT_SUCCESS;
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}
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} // namespace Kernel
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