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// Copyright 2021 yuzu Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#include "core/arm/exclusive_monitor.h"
#include "core/core.h"
#include "core/hle/kernel/k_address_arbiter.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/kernel.h"
#include "core/hle/kernel/svc_results.h"
#include "core/hle/kernel/time_manager.h"
#include "core/memory.h"
namespace Kernel {
KAddressArbiter::KAddressArbiter(Core::System& system_)
: system{system_}, kernel{system.Kernel()} {}
KAddressArbiter::~KAddressArbiter() = default;
namespace {
bool ReadFromUser(Core::System& system, s32* out, VAddr address) {
*out = system.Memory().Read32(address);
return true;
}
bool DecrementIfLessThan(Core::System& system, s32* out, VAddr address, s32 value) {
auto& monitor = system.Monitor();
const auto current_core = system.CurrentCoreIndex();
// TODO(bunnei): We should disable interrupts here via KScopedInterruptDisable.
// TODO(bunnei): We should call CanAccessAtomic(..) here.
// Load the value from the address.
const s32 current_value = static_cast<s32>(monitor.ExclusiveRead32(current_core, address));
// Compare it to the desired one.
if (current_value < value) {
// If less than, we want to try to decrement.
const s32 decrement_value = current_value - 1;
// Decrement and try to store.
if (!monitor.ExclusiveWrite32(current_core, address, static_cast<u32>(decrement_value))) {
// If we failed to store, try again.
DecrementIfLessThan(system, out, address, value);
}
} else {
// Otherwise, clear our exclusive hold and finish
monitor.ClearExclusive();
}
// We're done.
*out = current_value;
return true;
}
bool UpdateIfEqual(Core::System& system, s32* out, VAddr address, s32 value, s32 new_value) {
auto& monitor = system.Monitor();
const auto current_core = system.CurrentCoreIndex();
// TODO(bunnei): We should disable interrupts here via KScopedInterruptDisable.
// TODO(bunnei): We should call CanAccessAtomic(..) here.
// Load the value from the address.
const s32 current_value = static_cast<s32>(monitor.ExclusiveRead32(current_core, address));
// Compare it to the desired one.
if (current_value == value) {
// If equal, we want to try to write the new value.
// Try to store.
if (!monitor.ExclusiveWrite32(current_core, address, static_cast<u32>(new_value))) {
// If we failed to store, try again.
UpdateIfEqual(system, out, address, value, new_value);
}
} else {
// Otherwise, clear our exclusive hold and finish.
monitor.ClearExclusive();
}
// We're done.
*out = current_value;
return true;
}
} // namespace
ResultCode KAddressArbiter::Signal(VAddr addr, s32 count) {
// Perform signaling.
s32 num_waiters{};
{
KScopedSchedulerLock sl(kernel);
auto it = thread_tree.nfind_light({addr, -1});
while ((it != thread_tree.end()) && (count <= 0 || num_waiters < count) &&
(it->GetAddressArbiterKey() == addr)) {
KThread* target_thread = std::addressof(*it);
target_thread->SetSyncedObject(nullptr, RESULT_SUCCESS);
ASSERT(target_thread->IsWaitingForAddressArbiter());
target_thread->Wakeup();
it = thread_tree.erase(it);
target_thread->ClearAddressArbiter();
++num_waiters;
}
}
return RESULT_SUCCESS;
}
ResultCode KAddressArbiter::SignalAndIncrementIfEqual(VAddr addr, s32 value, s32 count) {
// Perform signaling.
s32 num_waiters{};
{
KScopedSchedulerLock sl(kernel);
// Check the userspace value.
s32 user_value{};
R_UNLESS(UpdateIfEqual(system, &user_value, addr, value, value + 1),
Svc::ResultInvalidCurrentMemory);
if (user_value != value) {
return Svc::ResultInvalidState;
}
auto it = thread_tree.nfind_light({addr, -1});
while ((it != thread_tree.end()) && (count <= 0 || num_waiters < count) &&
(it->GetAddressArbiterKey() == addr)) {
KThread* target_thread = std::addressof(*it);
target_thread->SetSyncedObject(nullptr, RESULT_SUCCESS);
ASSERT(target_thread->IsWaitingForAddressArbiter());
target_thread->Wakeup();
it = thread_tree.erase(it);
target_thread->ClearAddressArbiter();
++num_waiters;
}
}
return RESULT_SUCCESS;
}
ResultCode KAddressArbiter::SignalAndModifyByWaitingCountIfEqual(VAddr addr, s32 value, s32 count) {
// Perform signaling.
s32 num_waiters{};
{
[[maybe_unused]] const KScopedSchedulerLock sl(kernel);
auto it = thread_tree.nfind_light({addr, -1});
// Determine the updated value.
s32 new_value{};
if (count <= 0) {
if (it != thread_tree.end() && it->GetAddressArbiterKey() == addr) {
new_value = value - 2;
} else {
new_value = value + 1;
}
} else {
if (it != thread_tree.end() && it->GetAddressArbiterKey() == addr) {
auto tmp_it = it;
s32 tmp_num_waiters{};
while (++tmp_it != thread_tree.end() && tmp_it->GetAddressArbiterKey() == addr) {
if (tmp_num_waiters++ >= count) {
break;
}
}
if (tmp_num_waiters < count) {
new_value = value - 1;
} else {
new_value = value;
}
} else {
new_value = value + 1;
}
}
// Check the userspace value.
s32 user_value{};
bool succeeded{};
if (value != new_value) {
succeeded = UpdateIfEqual(system, &user_value, addr, value, new_value);
} else {
succeeded = ReadFromUser(system, &user_value, addr);
}
R_UNLESS(succeeded, Svc::ResultInvalidCurrentMemory);
if (user_value != value) {
return Svc::ResultInvalidState;
}
while ((it != thread_tree.end()) && (count <= 0 || num_waiters < count) &&
(it->GetAddressArbiterKey() == addr)) {
KThread* target_thread = std::addressof(*it);
target_thread->SetSyncedObject(nullptr, RESULT_SUCCESS);
ASSERT(target_thread->IsWaitingForAddressArbiter());
target_thread->Wakeup();
it = thread_tree.erase(it);
target_thread->ClearAddressArbiter();
++num_waiters;
}
}
return RESULT_SUCCESS;
}
ResultCode KAddressArbiter::WaitIfLessThan(VAddr addr, s32 value, bool decrement, s64 timeout) {
// Prepare to wait.
KThread* cur_thread = kernel.CurrentScheduler()->GetCurrentThread();
{
KScopedSchedulerLockAndSleep slp{kernel, cur_thread, timeout};
// Check that the thread isn't terminating.
if (cur_thread->IsTerminationRequested()) {
slp.CancelSleep();
return Svc::ResultTerminationRequested;
}
// Set the synced object.
cur_thread->SetSyncedObject(nullptr, Svc::ResultTimedOut);
// Read the value from userspace.
s32 user_value{};
bool succeeded{};
if (decrement) {
succeeded = DecrementIfLessThan(system, &user_value, addr, value);
} else {
succeeded = ReadFromUser(system, &user_value, addr);
}
if (!succeeded) {
slp.CancelSleep();
return Svc::ResultInvalidCurrentMemory;
}
// Check that the value is less than the specified one.
if (user_value >= value) {
slp.CancelSleep();
return Svc::ResultInvalidState;
}
// Check that the timeout is non-zero.
if (timeout == 0) {
slp.CancelSleep();
return Svc::ResultTimedOut;
}
// Set the arbiter.
cur_thread->SetAddressArbiter(&thread_tree, addr);
thread_tree.insert(*cur_thread);
cur_thread->SetState(ThreadState::Waiting);
cur_thread->SetWaitReasonForDebugging(ThreadWaitReasonForDebugging::Arbitration);
}
// Cancel the timer wait.
kernel.TimeManager().UnscheduleTimeEvent(cur_thread);
// Remove from the address arbiter.
{
KScopedSchedulerLock sl(kernel);
if (cur_thread->IsWaitingForAddressArbiter()) {
thread_tree.erase(thread_tree.iterator_to(*cur_thread));
cur_thread->ClearAddressArbiter();
}
}
// Get the result.
KSynchronizationObject* dummy{};
return cur_thread->GetWaitResult(&dummy);
}
ResultCode KAddressArbiter::WaitIfEqual(VAddr addr, s32 value, s64 timeout) {
// Prepare to wait.
KThread* cur_thread = kernel.CurrentScheduler()->GetCurrentThread();
{
KScopedSchedulerLockAndSleep slp{kernel, cur_thread, timeout};
// Check that the thread isn't terminating.
if (cur_thread->IsTerminationRequested()) {
slp.CancelSleep();
return Svc::ResultTerminationRequested;
}
// Set the synced object.
cur_thread->SetSyncedObject(nullptr, Svc::ResultTimedOut);
// Read the value from userspace.
s32 user_value{};
if (!ReadFromUser(system, &user_value, addr)) {
slp.CancelSleep();
return Svc::ResultInvalidCurrentMemory;
}
// Check that the value is equal.
if (value != user_value) {
slp.CancelSleep();
return Svc::ResultInvalidState;
}
// Check that the timeout is non-zero.
if (timeout == 0) {
slp.CancelSleep();
return Svc::ResultTimedOut;
}
// Set the arbiter.
cur_thread->SetAddressArbiter(&thread_tree, addr);
thread_tree.insert(*cur_thread);
cur_thread->SetState(ThreadState::Waiting);
cur_thread->SetWaitReasonForDebugging(ThreadWaitReasonForDebugging::Arbitration);
}
// Cancel the timer wait.
kernel.TimeManager().UnscheduleTimeEvent(cur_thread);
// Remove from the address arbiter.
{
KScopedSchedulerLock sl(kernel);
if (cur_thread->IsWaitingForAddressArbiter()) {
thread_tree.erase(thread_tree.iterator_to(*cur_thread));
cur_thread->ClearAddressArbiter();
}
}
// Get the result.
KSynchronizationObject* dummy{};
return cur_thread->GetWaitResult(&dummy);
}
} // namespace Kernel
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