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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <Kernel/Memory/AllocationStrategy.h>
#include <Kernel/Memory/MemoryManager.h>
#include <Kernel/Memory/PageFaultResponse.h>
#include <Kernel/Memory/VMObject.h>
#include <Kernel/PhysicalAddress.h>
namespace Kernel::Memory {
class AnonymousVMObject final : public VMObject {
public:
virtual ~AnonymousVMObject() override;
static ErrorOr<NonnullRefPtr<AnonymousVMObject>> try_create_with_size(size_t, AllocationStrategy);
static ErrorOr<NonnullRefPtr<AnonymousVMObject>> try_create_for_physical_range(PhysicalAddress paddr, size_t size);
static ErrorOr<NonnullRefPtr<AnonymousVMObject>> try_create_with_physical_pages(Span<NonnullRefPtr<PhysicalPage>>);
static ErrorOr<NonnullRefPtr<AnonymousVMObject>> try_create_purgeable_with_size(size_t, AllocationStrategy);
static ErrorOr<NonnullRefPtr<AnonymousVMObject>> try_create_physically_contiguous_with_size(size_t);
virtual ErrorOr<NonnullRefPtr<VMObject>> try_clone() override;
[[nodiscard]] NonnullRefPtr<PhysicalPage> allocate_committed_page(Badge<Region>);
PageFaultResponse handle_cow_fault(size_t, VirtualAddress);
size_t cow_pages() const;
bool should_cow(size_t page_index, bool) const;
void set_should_cow(size_t page_index, bool);
bool is_purgeable() const { return m_purgeable; }
bool is_volatile() const { return m_volatile; }
ErrorOr<void> set_volatile(bool is_volatile, bool& was_purged);
size_t purge();
private:
class SharedCommittedCowPages;
explicit AnonymousVMObject(size_t, AllocationStrategy, Optional<CommittedPhysicalPageSet>);
explicit AnonymousVMObject(PhysicalAddress, size_t);
explicit AnonymousVMObject(Span<NonnullRefPtr<PhysicalPage>>);
explicit AnonymousVMObject(AnonymousVMObject const&, NonnullRefPtr<SharedCommittedCowPages>);
virtual StringView class_name() const override { return "AnonymousVMObject"sv; }
AnonymousVMObject& operator=(AnonymousVMObject const&) = delete;
AnonymousVMObject& operator=(AnonymousVMObject&&) = delete;
AnonymousVMObject(AnonymousVMObject&&) = delete;
virtual bool is_anonymous() const override { return true; }
Bitmap& ensure_cow_map();
void ensure_or_reset_cow_map();
Optional<CommittedPhysicalPageSet> m_unused_committed_pages;
Bitmap m_cow_map;
// AnonymousVMObject shares committed COW pages with cloned children (happens on fork)
class SharedCommittedCowPages : public RefCounted<SharedCommittedCowPages> {
AK_MAKE_NONCOPYABLE(SharedCommittedCowPages);
public:
SharedCommittedCowPages() = delete;
explicit SharedCommittedCowPages(CommittedPhysicalPageSet&&);
~SharedCommittedCowPages();
[[nodiscard]] bool is_empty() const { return m_committed_pages.is_empty(); }
[[nodiscard]] NonnullRefPtr<PhysicalPage> take_one();
void uncommit_one();
private:
Spinlock m_lock;
CommittedPhysicalPageSet m_committed_pages;
};
RefPtr<SharedCommittedCowPages> m_shared_committed_cow_pages;
bool m_purgeable { false };
bool m_volatile { false };
bool m_was_purged { false };
};
}
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