mirror of
https://github.com/RGBCube/serenity
synced 2025-05-31 09:48:11 +00:00
02a95a196f
This patch stops using VirtualRangeAllocator in AddressSpace and instead looks for holes in the region tree when allocating VM space. There are many benefits: - VirtualRangeAllocator is non-intrusive and would call kmalloc/kfree when used. This new solution is allocation-free. This was a source of unpleasant MM/kmalloc deadlocks. - We consolidate authority on what the address space looks like in a single place. Previously, we had both the range allocator *and* the region tree both being used to determine if an address was valid. Now there is only the region tree. - Deallocation of VM when splitting regions is no longer complicated, as we don't need to keep two separate trees in sync.
85 lines
2.3 KiB
C++
85 lines
2.3 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 <AK/Badge.h>
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#include <AK/HashMap.h>
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#include <AK/IntrusiveRedBlackTree.h>
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#include <AK/RefCounted.h>
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#include <AK/RefPtr.h>
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#include <Kernel/Forward.h>
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#include <Kernel/Memory/PhysicalPage.h>
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#include <Kernel/Memory/VirtualRangeAllocator.h>
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namespace Kernel::Memory {
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class PageDirectory : public RefCounted<PageDirectory> {
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friend class MemoryManager;
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public:
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static ErrorOr<NonnullRefPtr<PageDirectory>> try_create_for_userspace();
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static NonnullRefPtr<PageDirectory> must_create_kernel_page_directory();
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static RefPtr<PageDirectory> find_current();
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~PageDirectory();
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void allocate_kernel_directory();
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FlatPtr cr3() const
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{
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#if ARCH(X86_64)
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return m_pml4t->paddr().get();
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#else
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return m_directory_table->paddr().get();
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#endif
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}
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bool is_cr3_initialized() const
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{
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#if ARCH(X86_64)
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return m_pml4t;
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#else
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return m_directory_table;
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#endif
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}
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VirtualRangeAllocator& range_allocator() { return m_range_allocator; }
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VirtualRangeAllocator const& range_allocator() const { return m_range_allocator; }
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AddressSpace* address_space() { return m_space; }
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AddressSpace const* address_space() const { return m_space; }
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void set_space(Badge<AddressSpace>, AddressSpace& space) { m_space = &space; }
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RecursiveSpinlock& get_lock() { return m_lock; }
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// This has to be public to let the global singleton access the member pointer
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IntrusiveRedBlackTreeNode<FlatPtr, PageDirectory, RawPtr<PageDirectory>> m_tree_node;
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private:
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PageDirectory();
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static void register_page_directory(PageDirectory* directory);
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static void deregister_page_directory(PageDirectory* directory);
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AddressSpace* m_space { nullptr };
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VirtualRangeAllocator m_range_allocator;
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#if ARCH(X86_64)
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RefPtr<PhysicalPage> m_pml4t;
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#endif
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RefPtr<PhysicalPage> m_directory_table;
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#if ARCH(X86_64)
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RefPtr<PhysicalPage> m_directory_pages[512];
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#else
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RefPtr<PhysicalPage> m_directory_pages[4];
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#endif
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RecursiveSpinlock m_lock;
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};
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void activate_kernel_page_directory(PageDirectory const& pgd);
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void activate_page_directory(PageDirectory const& pgd, Thread* current_thread);
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}
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