1 /* 2 * AArch64-specific checksum implementation using NEON 3 * 4 * Copyright (c) 2020, Arm Limited. 5 * SPDX-License-Identifier: MIT 6 */ 7 8 #include "networking.h" 9 #include "../chksum_common.h" 10 11 #ifndef __ARM_NEON 12 #pragma GCC target("+simd") 13 #endif 14 15 #include <arm_neon.h> 16 17 always_inline 18 static inline uint64_t 19 slurp_head64(const void **pptr, uint32_t *nbytes) 20 { 21 Assert(*nbytes >= 8); 22 uint64_t sum = 0; 23 uint32_t off = (uintptr_t) *pptr % 8; 24 if (likely(off != 0)) 25 { 26 /* Get rid of bytes 0..off-1 */ 27 const unsigned char *ptr64 = align_ptr(*pptr, 8); 28 uint64_t mask = ALL_ONES << (CHAR_BIT * off); 29 uint64_t val = load64(ptr64) & mask; 30 /* Fold 64-bit sum to 33 bits */ 31 sum = val >> 32; 32 sum += (uint32_t) val; 33 *pptr = ptr64 + 8; 34 *nbytes -= 8 - off; 35 } 36 return sum; 37 } 38 39 always_inline 40 static inline uint64_t 41 slurp_tail64(uint64_t sum, const void *ptr, uint32_t nbytes) 42 { 43 Assert(nbytes < 8); 44 if (likely(nbytes != 0)) 45 { 46 /* Get rid of bytes 7..nbytes */ 47 uint64_t mask = ALL_ONES >> (CHAR_BIT * (8 - nbytes)); 48 Assert(__builtin_popcountl(mask) / CHAR_BIT == nbytes); 49 uint64_t val = load64(ptr) & mask; 50 sum += val >> 32; 51 sum += (uint32_t) val; 52 nbytes = 0; 53 } 54 Assert(nbytes == 0); 55 return sum; 56 } 57 58 unsigned short 59 __chksum_aarch64_simd(const void *ptr, unsigned int nbytes) 60 { 61 bool swap = (uintptr_t) ptr & 1; 62 uint64_t sum; 63 64 if (unlikely(nbytes < 50)) 65 { 66 sum = slurp_small(ptr, nbytes); 67 swap = false; 68 goto fold; 69 } 70 71 /* 8-byte align pointer */ 72 Assert(nbytes >= 8); 73 sum = slurp_head64(&ptr, &nbytes); 74 Assert(((uintptr_t) ptr & 7) == 0); 75 76 const uint32_t *may_alias ptr32 = ptr; 77 78 uint64x2_t vsum0 = { 0, 0 }; 79 uint64x2_t vsum1 = { 0, 0 }; 80 uint64x2_t vsum2 = { 0, 0 }; 81 uint64x2_t vsum3 = { 0, 0 }; 82 83 /* Sum groups of 64 bytes */ 84 for (uint32_t i = 0; i < nbytes / 64; i++) 85 { 86 uint32x4_t vtmp0 = vld1q_u32(ptr32); 87 uint32x4_t vtmp1 = vld1q_u32(ptr32 + 4); 88 uint32x4_t vtmp2 = vld1q_u32(ptr32 + 8); 89 uint32x4_t vtmp3 = vld1q_u32(ptr32 + 12); 90 vsum0 = vpadalq_u32(vsum0, vtmp0); 91 vsum1 = vpadalq_u32(vsum1, vtmp1); 92 vsum2 = vpadalq_u32(vsum2, vtmp2); 93 vsum3 = vpadalq_u32(vsum3, vtmp3); 94 ptr32 += 16; 95 } 96 nbytes %= 64; 97 98 /* Fold vsum2 and vsum3 into vsum0 and vsum1 */ 99 vsum0 = vpadalq_u32(vsum0, vreinterpretq_u32_u64(vsum2)); 100 vsum1 = vpadalq_u32(vsum1, vreinterpretq_u32_u64(vsum3)); 101 102 /* Add any trailing group of 32 bytes */ 103 if (nbytes & 32) 104 { 105 uint32x4_t vtmp0 = vld1q_u32(ptr32); 106 uint32x4_t vtmp1 = vld1q_u32(ptr32 + 4); 107 vsum0 = vpadalq_u32(vsum0, vtmp0); 108 vsum1 = vpadalq_u32(vsum1, vtmp1); 109 ptr32 += 8; 110 nbytes -= 32; 111 } 112 Assert(nbytes < 32); 113 114 /* Fold vsum1 into vsum0 */ 115 vsum0 = vpadalq_u32(vsum0, vreinterpretq_u32_u64(vsum1)); 116 117 /* Add any trailing group of 16 bytes */ 118 if (nbytes & 16) 119 { 120 uint32x4_t vtmp = vld1q_u32(ptr32); 121 vsum0 = vpadalq_u32(vsum0, vtmp); 122 ptr32 += 4; 123 nbytes -= 16; 124 } 125 Assert(nbytes < 16); 126 127 /* Add any trailing group of 8 bytes */ 128 if (nbytes & 8) 129 { 130 uint32x2_t vtmp = vld1_u32(ptr32); 131 vsum0 = vaddw_u32(vsum0, vtmp); 132 ptr32 += 2; 133 nbytes -= 8; 134 } 135 Assert(nbytes < 8); 136 137 uint64_t val = vaddlvq_u32(vreinterpretq_u32_u64(vsum0)); 138 sum += val >> 32; 139 sum += (uint32_t) val; 140 141 /* Handle any trailing 0..7 bytes */ 142 sum = slurp_tail64(sum, ptr32, nbytes); 143 144 fold: 145 return fold_and_swap(sum, swap); 146 } 147