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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.
50 lines
1.4 KiB
C++
50 lines
1.4 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/RedBlackTree.h>
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#include <AK/Traits.h>
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#include <Kernel/Locking/Spinlock.h>
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#include <Kernel/Memory/VirtualRange.h>
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namespace Kernel::Memory {
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class VirtualRangeAllocator {
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public:
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VirtualRangeAllocator();
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~VirtualRangeAllocator() = default;
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ErrorOr<void> initialize_with_range(VirtualAddress, size_t);
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ErrorOr<void> initialize_from_parent(VirtualRangeAllocator const&);
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ErrorOr<VirtualRange> try_allocate_anywhere(size_t, size_t alignment = PAGE_SIZE);
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ErrorOr<VirtualRange> try_allocate_specific(VirtualAddress, size_t);
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ErrorOr<VirtualRange> try_allocate_randomized(size_t, size_t alignment);
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void deallocate(VirtualRange const&);
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void dump() const;
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bool contains(VirtualRange const& range) const { return m_total_range.contains(range); }
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VirtualRange total_range() const { return m_total_range; }
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private:
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ErrorOr<void> carve_from_region(VirtualRange const& from, VirtualRange const&);
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RedBlackTree<FlatPtr, VirtualRange> m_available_ranges;
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VirtualRange m_total_range;
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mutable Spinlock m_lock;
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};
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}
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namespace AK {
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template<>
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struct Traits<Kernel::Memory::VirtualRange> : public GenericTraits<Kernel::Memory::VirtualRange> {
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static constexpr bool is_trivial() { return true; }
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};
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}
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