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55 lines
1.7 KiB
55 lines
1.7 KiB
4 months ago
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//===-- checksum.h ----------------------------------------------*- 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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#ifndef SCUDO_CHECKSUM_H_
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#define SCUDO_CHECKSUM_H_
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#include "internal_defs.h"
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// Hardware CRC32 is supported at compilation via the following:
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// - for i386 & x86_64: -msse4.2
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// - for ARM & AArch64: -march=armv8-a+crc or -mcrc
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// An additional check must be performed at runtime as well to make sure the
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// emitted instructions are valid on the target host.
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#ifdef __SSE4_2__
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#include <smmintrin.h>
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#define CRC32_INTRINSIC FIRST_32_SECOND_64(_mm_crc32_u32, _mm_crc32_u64)
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#endif
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#ifdef __ARM_FEATURE_CRC32
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#include <arm_acle.h>
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#define CRC32_INTRINSIC FIRST_32_SECOND_64(__crc32cw, __crc32cd)
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#endif
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namespace scudo {
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enum class Checksum : u8 {
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BSD = 0,
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HardwareCRC32 = 1,
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};
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// BSD checksum, unlike a software CRC32, doesn't use any array lookup. We save
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// significantly on memory accesses, as well as 1K of CRC32 table, on platforms
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// that do no support hardware CRC32. The checksum itself is 16-bit, which is at
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// odds with CRC32, but enough for our needs.
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inline u16 computeBSDChecksum(u16 Sum, uptr Data) {
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for (u8 I = 0; I < sizeof(Data); I++) {
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Sum = static_cast<u16>((Sum >> 1) | ((Sum & 1) << 15));
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Sum = static_cast<u16>(Sum + (Data & 0xff));
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Data >>= 8;
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}
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return Sum;
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}
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bool hasHardwareCRC32();
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WEAK u32 computeHardwareCRC32(u32 Crc, uptr Data);
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} // namespace scudo
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#endif // SCUDO_CHECKSUM_H_
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