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/*
* Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/NonnullRefPtr.h>
#include <Kernel/Memory/PhysicalAddress.h>
namespace Kernel::Memory {
enum class MayReturnToFreeList : bool {
No,
Yes
};
class PhysicalPage {
AK_MAKE_NONCOPYABLE(PhysicalPage);
AK_MAKE_NONMOVABLE(PhysicalPage);
friend class MemoryManager;
public:
PhysicalAddress paddr() const;
void ref() const
{
m_ref_count.fetch_add(1, AK::memory_order_relaxed);
}
void unref() const
{
if (m_ref_count.fetch_sub(1, AK::memory_order_acq_rel) == 1)
free_this();
}
static NonnullRefPtr<PhysicalPage> create(PhysicalAddress, MayReturnToFreeList may_return_to_freelist = MayReturnToFreeList::Yes);
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:
explicit PhysicalPage(MayReturnToFreeList may_return_to_freelist);
~PhysicalPage() = default;
void free_this() const;
mutable Atomic<u32> m_ref_count { 1 };
MayReturnToFreeList m_may_return_to_freelist { MayReturnToFreeList::Yes };
};
struct PhysicalPageEntry {
union {
// If it's a live PhysicalPage object:
struct {
PhysicalPage physical_page;
} allocated;
// If it's an entry in a PhysicalZone::Bucket's freelist.
struct {
i16 next_index;
i16 prev_index;
} freelist;
};
};
}
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