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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/NonnullRefPtr.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/Assertions.h>
#include <Kernel/Heap/SlabAllocator.h>
#include <Kernel/PhysicalAddress.h>
namespace Kernel {
class PhysicalPage {
friend class MemoryManager;
friend class PageDirectory;
friend class VMObject;
MAKE_SLAB_ALLOCATED(PhysicalPage);
AK_MAKE_NONMOVABLE(PhysicalPage);
public:
PhysicalAddress paddr() const { return m_paddr; }
void ref()
{
m_ref_count.fetch_add(1, AK::memory_order_acq_rel);
}
void unref()
{
if (m_ref_count.fetch_sub(1, AK::memory_order_acq_rel) == 1) {
if (m_may_return_to_freelist)
return_to_freelist();
delete this;
}
}
static NonnullRefPtr<PhysicalPage> create(PhysicalAddress, bool supervisor, bool may_return_to_freelist = true);
u32 ref_count() const { return m_ref_count.load(AK::memory_order_consume); }
bool is_shared_zero_page() const;
bool is_lazy_committed_page() const;
private:
PhysicalPage(PhysicalAddress paddr, bool supervisor, bool may_return_to_freelist = true);
~PhysicalPage() = default;
void return_to_freelist() const;
Atomic<u32> m_ref_count { 1 };
bool m_may_return_to_freelist { true };
bool m_supervisor { false };
PhysicalAddress m_paddr;
};
}
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