51 lines
1013 B
C++
51 lines
1013 B
C++
/*
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* \brief Kernel lock for multi-processor systems
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* \author Stefan Kalkowski
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* \date 2018-11-20
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*/
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/*
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* Copyright (C) 2019 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#include <base/lock_guard.h>
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#include <cpu/atomic.h>
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#include <cpu/memory_barrier.h>
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#include "cpu.h"
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#include "lock.h"
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#include "kernel.h"
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Kernel::Lock & Kernel::data_lock()
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{
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static Kernel::Lock lock;
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return lock;
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}
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void Kernel::Lock::lock()
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{
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/* check for the lock holder being the same cpu */
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if (_current_cpu == Cpu::executing_id()) {
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/* at least print an error message */
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Genode::raw("Cpu ", _current_cpu,
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" error: re-entered lock. Kernel exception?!");
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}
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while (!Genode::cmpxchg((volatile int*)&_locked, UNLOCKED, LOCKED)) { ; }
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_current_cpu = Cpu::executing_id();
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}
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void Kernel::Lock::unlock()
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{
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_current_cpu = INVALID;
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Genode::memory_barrier();
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_locked = UNLOCKED;
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}
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