mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
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100 lines
3.5 KiB
C++
100 lines
3.5 KiB
C++
/*
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* Copyright (c) 2018-2020 Atmosphère-NX
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <mesosphere.hpp>
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namespace ams::kern {
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void KLightLock::LockSlowPath(uintptr_t _owner, uintptr_t _cur_thread) {
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KThread *cur_thread = reinterpret_cast<KThread *>(_cur_thread);
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/* Pend the current thread waiting on the owner thread. */
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{
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KScopedSchedulerLock sl;
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/* Ensure we actually have locking to do. */
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if (AMS_UNLIKELY(m_tag.load(std::memory_order_relaxed) != _owner)) {
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return;
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}
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/* Add the current thread as a waiter on the owner. */
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KThread *owner_thread = reinterpret_cast<KThread *>(_owner & ~1ul);
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cur_thread->SetAddressKey(reinterpret_cast<uintptr_t>(std::addressof(m_tag)));
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owner_thread->AddWaiter(cur_thread);
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/* Set thread states. */
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if (AMS_LIKELY(cur_thread->GetState() == KThread::ThreadState_Runnable)) {
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cur_thread->SetState(KThread::ThreadState_Waiting);
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} else {
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KScheduler::SetSchedulerUpdateNeeded();
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}
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if (owner_thread->IsSuspended()) {
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owner_thread->ContinueIfHasKernelWaiters();
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}
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}
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/* We're no longer waiting on the lock owner. */
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{
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KScopedSchedulerLock sl;
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KThread *owner_thread = cur_thread->GetLockOwner();
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if (AMS_UNLIKELY(owner_thread)) {
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owner_thread->RemoveWaiter(cur_thread);
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KScheduler::SetSchedulerUpdateNeeded();
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}
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}
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}
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void KLightLock::UnlockSlowPath(uintptr_t _cur_thread) {
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KThread *owner_thread = reinterpret_cast<KThread *>(_cur_thread);
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/* Unlock. */
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{
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KScopedSchedulerLock sl;
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/* Get the next owner. */
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s32 num_waiters = 0;
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KThread *next_owner = owner_thread->RemoveWaiterByKey(std::addressof(num_waiters), reinterpret_cast<uintptr_t>(std::addressof(m_tag)));
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/* Pass the lock to the next owner. */
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uintptr_t next_tag = 0;
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if (next_owner) {
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next_tag = reinterpret_cast<uintptr_t>(next_owner);
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if (num_waiters > 1) {
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next_tag |= 0x1;
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}
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if (AMS_LIKELY(next_owner->GetState() == KThread::ThreadState_Waiting)) {
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next_owner->SetState(KThread::ThreadState_Runnable);
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} else {
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KScheduler::SetSchedulerUpdateNeeded();
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}
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if (next_owner->IsSuspended()) {
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next_owner->ContinueIfHasKernelWaiters();
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}
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}
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/* We may have unsuspended in the process of acquiring the lock, so we'll re-suspend now if so. */
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if (owner_thread->IsSuspended()) {
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owner_thread->TrySuspend();
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}
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/* Write the new tag value. */
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m_tag.store(next_tag);
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}
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}
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}
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