mirror of
https://github.com/Atmosphere-NX/Atmosphere.git
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74 lines
2.7 KiB
C++
74 lines
2.7 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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#pragma once
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#include <mesosphere/kern_common.hpp>
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#include <mesosphere/kern_select_cpu.hpp>
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#include <mesosphere/kern_k_current_context.hpp>
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#include <mesosphere/kern_k_scoped_lock.hpp>
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namespace ams::kern {
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class KLightLock {
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private:
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std::atomic<uintptr_t> tag;
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public:
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constexpr KLightLock() : tag(0) { /* ... */ }
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void Lock() {
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MESOSPHERE_ASSERT_THIS();
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const uintptr_t cur_thread = reinterpret_cast<uintptr_t>(GetCurrentThreadPointer());
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const uintptr_t cur_thread_tag = (cur_thread | 1);
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while (true) {
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uintptr_t old_tag = this->tag.load(std::memory_order_relaxed);
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while (!this->tag.compare_exchange_weak(old_tag, (old_tag == 0) ? cur_thread : old_tag | 1, std::memory_order_acquire)) {
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if ((old_tag | 1) == cur_thread_tag) {
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return;
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}
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}
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if ((old_tag == 0) || ((old_tag | 1) == cur_thread_tag)) {
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break;
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}
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this->LockSlowPath(old_tag | 1, cur_thread);
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}
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}
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void Unlock() {
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MESOSPHERE_ASSERT_THIS();
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const uintptr_t cur_thread = reinterpret_cast<uintptr_t>(GetCurrentThreadPointer());
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uintptr_t expected = cur_thread;
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do {
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if (expected != cur_thread) {
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return this->UnlockSlowPath(cur_thread);
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}
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} while (!this->tag.compare_exchange_weak(expected, 0, std::memory_order_release));
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}
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void LockSlowPath(uintptr_t owner, uintptr_t cur_thread);
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void UnlockSlowPath(uintptr_t cur_thread);
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bool IsLocked() const { return this->tag != 0; }
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bool IsLockedByCurrentThread() const { return (this->tag | 0x1ul) == (reinterpret_cast<uintptr_t>(GetCurrentThreadPointer()) | 0x1ul); }
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};
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using KScopedLightLock = KScopedLock<KLightLock>;
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}
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