3c74dc9f4d
This patch adds two macros to declare per-type allocators: - JS_DECLARE_ALLOCATOR(TypeName) - JS_DEFINE_ALLOCATOR(TypeName) When used, they add a type-specific CellAllocator that the Heap will delegate allocation requests to. The result of this is that GC objects of the same type always end up within the same HeapBlock, drastically reducing the ability to perform type confusion attacks. It also improves HeapBlock utilization, since each block now has cells sized exactly to the type used within that block. (Previously we only had a handful of block sizes available, and most GC allocations ended up with a large amount of slack in their tails.) There is a small performance hit from this, but I'm sure we can make up for it elsewhere. Note that the old size-based allocators still exist, and we fall back to them for any type that doesn't have its own CellAllocator.
50 lines
1.3 KiB
C++
50 lines
1.3 KiB
C++
/*
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* Copyright (c) 2021-2022, Linus Groh <linusg@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/StringView.h>
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#include <LibJS/Runtime/NativeFunction.h>
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namespace JS {
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struct AlreadyResolved final : public Cell {
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JS_CELL(AlreadyResolved, Cell);
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JS_DECLARE_ALLOCATOR(AlreadyResolved);
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bool value { false };
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protected:
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// Allocated cells must be >= sizeof(FreelistEntry), which is 24 bytes -
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// but AlreadyResolved is only 16 bytes without this.
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u8 dummy[8];
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};
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class PromiseResolvingFunction final : public NativeFunction {
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JS_OBJECT(PromiseResolvingFunction, NativeFunction);
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JS_DECLARE_ALLOCATOR(PromiseResolvingFunction);
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public:
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using FunctionType = Function<Value(VM&, Promise&, AlreadyResolved&)>;
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static NonnullGCPtr<PromiseResolvingFunction> create(Realm&, Promise&, AlreadyResolved&, FunctionType);
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virtual void initialize(Realm&) override;
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virtual ~PromiseResolvingFunction() override = default;
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virtual ThrowCompletionOr<Value> call() override;
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private:
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explicit PromiseResolvingFunction(Promise&, AlreadyResolved&, FunctionType, Object& prototype);
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virtual void visit_edges(Visitor&) override;
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NonnullGCPtr<Promise> m_promise;
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NonnullGCPtr<AlreadyResolved> m_already_resolved;
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FunctionType m_native_function;
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};
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}
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