mirror of
https://github.com/RGBCube/serenity
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fa627c1eb2
We had issues with committed physical pages getting miscounted in some situations, and instead of figuring out what was going wrong and making sure all the commits had matching uncommits, this patch makes the problem go away by adding an RAII class to manage this instead. :^) MemoryManager::commit_user_physical_pages() now returns an (optional) CommittedPhysicalPageSet. You can then allocate pages from the page set by calling take_one() on it. Any unallocated pages are uncommitted upon destruction of the page set.
86 lines
3 KiB
C++
86 lines
3 KiB
C++
/*
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* Copyright (c) 2018-2020, 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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#pragma once
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#include <Kernel/PhysicalAddress.h>
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#include <Kernel/VM/AllocationStrategy.h>
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#include <Kernel/VM/MemoryManager.h>
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#include <Kernel/VM/PageFaultResponse.h>
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#include <Kernel/VM/VMObject.h>
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namespace Kernel {
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class AnonymousVMObject final : public VMObject {
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public:
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virtual ~AnonymousVMObject() override;
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static RefPtr<AnonymousVMObject> try_create_with_size(size_t, AllocationStrategy);
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static RefPtr<AnonymousVMObject> try_create_for_physical_range(PhysicalAddress paddr, size_t size);
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static RefPtr<AnonymousVMObject> try_create_with_physical_pages(Span<NonnullRefPtr<PhysicalPage>>);
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static RefPtr<AnonymousVMObject> try_create_purgeable_with_size(size_t, AllocationStrategy);
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static RefPtr<AnonymousVMObject> try_create_physically_contiguous_with_size(size_t);
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virtual RefPtr<VMObject> try_clone() override;
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[[nodiscard]] NonnullRefPtr<PhysicalPage> allocate_committed_page(Badge<Region>);
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PageFaultResponse handle_cow_fault(size_t, VirtualAddress);
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size_t cow_pages() const;
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bool should_cow(size_t page_index, bool) const;
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void set_should_cow(size_t page_index, bool);
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bool is_purgeable() const { return m_purgeable; }
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bool is_volatile() const { return m_volatile; }
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KResult set_volatile(bool is_volatile, bool& was_purged);
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size_t purge();
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private:
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explicit AnonymousVMObject(size_t, AllocationStrategy, Optional<CommittedPhysicalPageSet>);
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explicit AnonymousVMObject(PhysicalAddress, size_t);
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explicit AnonymousVMObject(Span<NonnullRefPtr<PhysicalPage>>);
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explicit AnonymousVMObject(AnonymousVMObject const&);
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virtual StringView class_name() const override { return "AnonymousVMObject"sv; }
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AnonymousVMObject& operator=(AnonymousVMObject const&) = delete;
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AnonymousVMObject& operator=(AnonymousVMObject&&) = delete;
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AnonymousVMObject(AnonymousVMObject&&) = delete;
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virtual bool is_anonymous() const override { return true; }
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Bitmap& ensure_cow_map();
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void ensure_or_reset_cow_map();
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Optional<CommittedPhysicalPageSet> m_unused_committed_pages;
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Bitmap m_cow_map;
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// AnonymousVMObject shares committed COW pages with cloned children (happens on fork)
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class SharedCommittedCowPages : public RefCounted<SharedCommittedCowPages> {
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AK_MAKE_NONCOPYABLE(SharedCommittedCowPages);
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public:
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SharedCommittedCowPages() = delete;
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explicit SharedCommittedCowPages(CommittedPhysicalPageSet&&);
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~SharedCommittedCowPages();
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[[nodiscard]] NonnullRefPtr<PhysicalPage> take_one();
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[[nodiscard]] bool is_empty() const { return m_committed_pages.is_empty(); }
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public:
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SpinLock<u8> m_lock;
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CommittedPhysicalPageSet m_committed_pages;
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};
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RefPtr<SharedCommittedCowPages> m_shared_committed_cow_pages;
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bool m_purgeable { false };
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bool m_volatile { false };
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bool m_was_purged { false };
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};
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}
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