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64 lines
2.1 KiB
64 lines
2.1 KiB
//===-- utilities.cpp -------------------------------------------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "gwp_asan/utilities.h"
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#include <assert.h>
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namespace gwp_asan {
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// See `bionic/tests/malloc_test.cpp` in the Android source for documentation
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// regarding their alignment guarantees. We always round up to the closest
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// 8-byte window. As GWP-ASan's malloc(X) can always get exactly an X-sized
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// allocation, an allocation that rounds up to 16-bytes will always be given a
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// 16-byte aligned allocation.
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static size_t alignBionic(size_t RealAllocationSize) {
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if (RealAllocationSize % 8 == 0)
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return RealAllocationSize;
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return RealAllocationSize + 8 - (RealAllocationSize % 8);
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}
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static size_t alignPowerOfTwo(size_t RealAllocationSize) {
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if (RealAllocationSize <= 2)
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return RealAllocationSize;
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if (RealAllocationSize <= 4)
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return 4;
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if (RealAllocationSize <= 8)
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return 8;
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if (RealAllocationSize % 16 == 0)
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return RealAllocationSize;
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return RealAllocationSize + 16 - (RealAllocationSize % 16);
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}
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#ifdef __BIONIC__
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static constexpr AlignmentStrategy PlatformDefaultAlignment =
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AlignmentStrategy::BIONIC;
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#else // __BIONIC__
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static constexpr AlignmentStrategy PlatformDefaultAlignment =
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AlignmentStrategy::POWER_OF_TWO;
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#endif // __BIONIC__
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size_t rightAlignedAllocationSize(size_t RealAllocationSize,
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AlignmentStrategy Align) {
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assert(RealAllocationSize > 0);
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if (Align == AlignmentStrategy::DEFAULT)
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Align = PlatformDefaultAlignment;
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switch (Align) {
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case AlignmentStrategy::BIONIC:
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return alignBionic(RealAllocationSize);
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case AlignmentStrategy::POWER_OF_TWO:
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return alignPowerOfTwo(RealAllocationSize);
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case AlignmentStrategy::PERFECT:
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return RealAllocationSize;
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case AlignmentStrategy::DEFAULT:
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__builtin_unreachable();
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}
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__builtin_unreachable();
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}
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} // namespace gwp_asan
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