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https://github.com/LadybirdBrowser/ladybird.git
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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.
62 lines
1.6 KiB
C++
62 lines
1.6 KiB
C++
/*
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* Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2021, Leon Albrecht <leon2002.la@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/Vector.h>
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#include <Kernel/Memory/MemoryManager.h>
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#include <Kernel/Memory/VirtualRange.h>
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#include <LibC/limits.h>
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namespace Kernel::Memory {
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Vector<VirtualRange, 2> VirtualRange::carve(VirtualRange const& taken) const
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{
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VERIFY((taken.size() % PAGE_SIZE) == 0);
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Vector<VirtualRange, 2> parts;
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if (taken == *this)
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return {};
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if (taken.base() > base())
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parts.append({ base(), taken.base().get() - base().get() });
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if (taken.end() < end())
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parts.append({ taken.end(), end().get() - taken.end().get() });
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return parts;
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}
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bool VirtualRange::intersects(VirtualRange const& other) const
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{
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auto a = *this;
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auto b = other;
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if (a.base() > b.base())
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swap(a, b);
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return a.base() < b.end() && b.base() < a.end();
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}
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VirtualRange VirtualRange::intersect(VirtualRange const& other) const
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{
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if (*this == other) {
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return *this;
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}
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auto new_base = max(base(), other.base());
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auto new_end = min(end(), other.end());
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VERIFY(new_base < new_end);
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return VirtualRange(new_base, (new_end - new_base).get());
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}
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ErrorOr<VirtualRange> VirtualRange::expand_to_page_boundaries(FlatPtr address, size_t size)
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{
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if ((address + size) < address)
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return EINVAL;
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auto base = VirtualAddress { address }.page_base();
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auto end = TRY(page_round_up(address + size));
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return VirtualRange { base, end - base.get() };
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}
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}
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