mirror of
https://github.com/RGBCube/serenity
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cf16b2c8e6
This forces anyone who wants to look into and/or manipulate an address space to lock it. And this replaces the previous, more flimsy, manual spinlock use. Note that pointers *into* the address space are not safe to use after you unlock the space. We've got many issues like this, and we'll have to track those down as wlel.
74 lines
1.6 KiB
C++
74 lines
1.6 KiB
C++
/*
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* Copyright (c) 2020-2022, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Arch/Spinlock.h>
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namespace Kernel {
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u32 Spinlock::lock()
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{
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u32 prev_flags = cpu_flags();
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Processor::enter_critical();
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cli();
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while (m_lock.exchange(1, AK::memory_order_acquire) != 0)
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Processor::wait_check();
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track_lock_acquire(m_rank);
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return prev_flags;
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}
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void Spinlock::unlock(u32 prev_flags)
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{
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VERIFY(is_locked());
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track_lock_release(m_rank);
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m_lock.store(0, AK::memory_order_release);
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Processor::leave_critical();
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if ((prev_flags & 0x200) != 0)
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sti();
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else
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cli();
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}
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u32 RecursiveSpinlock::lock()
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{
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u32 prev_flags = cpu_flags();
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cli();
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Processor::enter_critical();
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auto& proc = Processor::current();
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FlatPtr cpu = FlatPtr(&proc);
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FlatPtr expected = 0;
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while (!m_lock.compare_exchange_strong(expected, cpu, AK::memory_order_acq_rel)) {
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if (expected == cpu)
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break;
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Processor::wait_check();
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expected = 0;
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}
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if (m_recursions == 0)
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track_lock_acquire(m_rank);
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m_recursions++;
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return prev_flags;
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}
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void RecursiveSpinlock::unlock(u32 prev_flags)
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{
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VERIFY_INTERRUPTS_DISABLED();
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VERIFY(m_recursions > 0);
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VERIFY(m_lock.load(AK::memory_order_relaxed) == FlatPtr(&Processor::current()));
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if (--m_recursions == 0) {
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track_lock_release(m_rank);
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m_lock.store(0, AK::memory_order_release);
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}
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Processor::leave_critical();
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if ((prev_flags & 0x200) != 0)
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sti();
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else
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cli();
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}
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}
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