| 1 | //===-- checksum.h ----------------------------------------------*- C++ -*-===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #ifndef SCUDO_CHECKSUM_H_ |
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| 10 | #define SCUDO_CHECKSUM_H_ |
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| 11 | |
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| 12 | #include "internal_defs.h" |
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| 13 | |
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| 14 | // Hardware CRC32 is supported at compilation via the following: |
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| 15 | // - for i386 & x86_64: -mcrc32 (earlier: -msse4.2) |
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| 16 | // - for ARM & AArch64: -march=armv8-a+crc or -mcrc |
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| 17 | // An additional check must be performed at runtime as well to make sure the |
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| 18 | // emitted instructions are valid on the target host. |
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| 19 | |
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| 20 | #if defined(__CRC32__) |
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| 21 | // NB: clang has <crc32intrin.h> but GCC does not |
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| 22 | #include <smmintrin.h> |
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| 23 | #define CRC32_INTRINSIC \ |
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| 24 | FIRST_32_SECOND_64(__builtin_ia32_crc32si, __builtin_ia32_crc32di) |
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| 25 | #elif defined(__SSE4_2__) |
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| 26 | #include <smmintrin.h> |
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| 27 | #define CRC32_INTRINSIC FIRST_32_SECOND_64(_mm_crc32_u32, _mm_crc32_u64) |
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| 28 | #endif |
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| 29 | #ifdef __ARM_FEATURE_CRC32 |
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| 30 | #include <arm_acle.h> |
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| 31 | #define CRC32_INTRINSIC FIRST_32_SECOND_64(__crc32cw, __crc32cd) |
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| 32 | #endif |
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| 33 | #ifdef __loongarch__ |
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| 34 | #include <larchintrin.h> |
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| 35 | #define CRC32_INTRINSIC FIRST_32_SECOND_64(__crcc_w_w_w, __crcc_w_d_w) |
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| 36 | #endif |
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| 37 | |
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| 38 | namespace scudo { |
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| 39 | |
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| 40 | enum class Checksum : u8 { |
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| 41 | BSD = 0, |
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| 42 | HardwareCRC32 = 1, |
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| 43 | }; |
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| 44 | |
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| 45 | // BSD checksum, unlike a software CRC32, doesn't use any array lookup. We save |
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| 46 | // significantly on memory accesses, as well as 1K of CRC32 table, on platforms |
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| 47 | // that do no support hardware CRC32. The checksum itself is 16-bit, which is at |
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| 48 | // odds with CRC32, but enough for our needs. |
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| 49 | inline u16 computeBSDChecksum(u16 Sum, uptr Data) { |
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| 50 | for (u8 I = 0; I < sizeof(Data); I++) { |
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| 51 | Sum = static_cast<u16>((Sum >> 1) | ((Sum & 1) << 15)); |
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| 52 | Sum = static_cast<u16>(Sum + (Data & 0xff)); |
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| 53 | Data >>= 8; |
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| 54 | } |
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| 55 | return Sum; |
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| 56 | } |
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| 57 | |
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| 58 | bool hasHardwareCRC32(); |
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| 59 | WEAK u32 computeHardwareCRC32(u32 Crc, uptr Data); |
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| 60 | |
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| 61 | } // namespace scudo |
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| 62 | |
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| 63 | #endif // SCUDO_CHECKSUM_H_ |
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| 64 | |
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