| ######################################################################## |
| # Implement fast CRC-T10DIF computation with SSE and PCLMULQDQ instructions |
| # |
| # Copyright (c) 2013, Intel Corporation |
| # |
| # Authors: |
| # Erdinc Ozturk <erdinc.ozturk@intel.com> |
| # Vinodh Gopal <vinodh.gopal@intel.com> |
| # James Guilford <james.guilford@intel.com> |
| # Tim Chen <tim.c.chen@linux.intel.com> |
| # |
| # This software is available to you under a choice of one of two |
| # licenses. You may choose to be licensed under the terms of the GNU |
| # General Public License (GPL) Version 2, available from the file |
| # COPYING in the main directory of this source tree, or the |
| # OpenIB.org BSD license below: |
| # |
| # Redistribution and use in source and binary forms, with or without |
| # modification, are permitted provided that the following conditions are |
| # met: |
| # |
| # * Redistributions of source code must retain the above copyright |
| # notice, this list of conditions and the following disclaimer. |
| # |
| # * Redistributions in binary form must reproduce the above copyright |
| # notice, this list of conditions and the following disclaimer in the |
| # documentation and/or other materials provided with the |
| # distribution. |
| # |
| # * Neither the name of the Intel Corporation nor the names of its |
| # contributors may be used to endorse or promote products derived from |
| # this software without specific prior written permission. |
| # |
| # |
| # THIS SOFTWARE IS PROVIDED BY INTEL CORPORATION ""AS IS"" AND ANY |
| # EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| # PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL INTEL CORPORATION OR |
| # CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, |
| # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, |
| # PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR |
| # PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF |
| # LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING |
| # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS |
| # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| # |
| # Reference paper titled "Fast CRC Computation for Generic |
| # Polynomials Using PCLMULQDQ Instruction" |
| # URL: http://www.intel.com/content/dam/www/public/us/en/documents |
| # /white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf |
| # |
| |
| #include <linux/linkage.h> |
| |
| .text |
| |
| #define init_crc %edi |
| #define buf %rsi |
| #define len %rdx |
| |
| #define FOLD_CONSTS %xmm10 |
| #define BSWAP_MASK %xmm11 |
| |
| # Fold reg1, reg2 into the next 32 data bytes, storing the result back into |
| # reg1, reg2. |
| .macro fold_32_bytes offset, reg1, reg2 |
| movdqu \offset(buf), %xmm9 |
| movdqu \offset+16(buf), %xmm12 |
| pshufb BSWAP_MASK, %xmm9 |
| pshufb BSWAP_MASK, %xmm12 |
| movdqa \reg1, %xmm8 |
| movdqa \reg2, %xmm13 |
| pclmulqdq $0x00, FOLD_CONSTS, \reg1 |
| pclmulqdq $0x11, FOLD_CONSTS, %xmm8 |
| pclmulqdq $0x00, FOLD_CONSTS, \reg2 |
| pclmulqdq $0x11, FOLD_CONSTS, %xmm13 |
| pxor %xmm9 , \reg1 |
| xorps %xmm8 , \reg1 |
| pxor %xmm12, \reg2 |
| xorps %xmm13, \reg2 |
| .endm |
| |
| # Fold src_reg into dst_reg. |
| .macro fold_16_bytes src_reg, dst_reg |
| movdqa \src_reg, %xmm8 |
| pclmulqdq $0x11, FOLD_CONSTS, \src_reg |
| pclmulqdq $0x00, FOLD_CONSTS, %xmm8 |
| pxor %xmm8, \dst_reg |
| xorps \src_reg, \dst_reg |
| .endm |
| |
| # |
| # u16 crc_t10dif_pcl(u16 init_crc, const *u8 buf, size_t len); |
| # |
| # Assumes len >= 16. |
| # |
| SYM_FUNC_START(crc_t10dif_pcl) |
| |
| movdqa .Lbswap_mask(%rip), BSWAP_MASK |
| |
| # For sizes less than 256 bytes, we can't fold 128 bytes at a time. |
| cmp $256, len |
| jl .Lless_than_256_bytes |
| |
| # Load the first 128 data bytes. Byte swapping is necessary to make the |
| # bit order match the polynomial coefficient order. |
| movdqu 16*0(buf), %xmm0 |
| movdqu 16*1(buf), %xmm1 |
| movdqu 16*2(buf), %xmm2 |
| movdqu 16*3(buf), %xmm3 |
| movdqu 16*4(buf), %xmm4 |
| movdqu 16*5(buf), %xmm5 |
| movdqu 16*6(buf), %xmm6 |
| movdqu 16*7(buf), %xmm7 |
| add $128, buf |
| pshufb BSWAP_MASK, %xmm0 |
| pshufb BSWAP_MASK, %xmm1 |
| pshufb BSWAP_MASK, %xmm2 |
| pshufb BSWAP_MASK, %xmm3 |
| pshufb BSWAP_MASK, %xmm4 |
| pshufb BSWAP_MASK, %xmm5 |
| pshufb BSWAP_MASK, %xmm6 |
| pshufb BSWAP_MASK, %xmm7 |
| |
| # XOR the first 16 data *bits* with the initial CRC value. |
| pxor %xmm8, %xmm8 |
| pinsrw $7, init_crc, %xmm8 |
| pxor %xmm8, %xmm0 |
| |
| movdqa .Lfold_across_128_bytes_consts(%rip), FOLD_CONSTS |
| |
| # Subtract 128 for the 128 data bytes just consumed. Subtract another |
| # 128 to simplify the termination condition of the following loop. |
| sub $256, len |
| |
| # While >= 128 data bytes remain (not counting xmm0-7), fold the 128 |
| # bytes xmm0-7 into them, storing the result back into xmm0-7. |
| .Lfold_128_bytes_loop: |
| fold_32_bytes 0, %xmm0, %xmm1 |
| fold_32_bytes 32, %xmm2, %xmm3 |
| fold_32_bytes 64, %xmm4, %xmm5 |
| fold_32_bytes 96, %xmm6, %xmm7 |
| add $128, buf |
| sub $128, len |
| jge .Lfold_128_bytes_loop |
| |
| # Now fold the 112 bytes in xmm0-xmm6 into the 16 bytes in xmm7. |
| |
| # Fold across 64 bytes. |
| movdqa .Lfold_across_64_bytes_consts(%rip), FOLD_CONSTS |
| fold_16_bytes %xmm0, %xmm4 |
| fold_16_bytes %xmm1, %xmm5 |
| fold_16_bytes %xmm2, %xmm6 |
| fold_16_bytes %xmm3, %xmm7 |
| # Fold across 32 bytes. |
| movdqa .Lfold_across_32_bytes_consts(%rip), FOLD_CONSTS |
| fold_16_bytes %xmm4, %xmm6 |
| fold_16_bytes %xmm5, %xmm7 |
| # Fold across 16 bytes. |
| movdqa .Lfold_across_16_bytes_consts(%rip), FOLD_CONSTS |
| fold_16_bytes %xmm6, %xmm7 |
| |
| # Add 128 to get the correct number of data bytes remaining in 0...127 |
| # (not counting xmm7), following the previous extra subtraction by 128. |
| # Then subtract 16 to simplify the termination condition of the |
| # following loop. |
| add $128-16, len |
| |
| # While >= 16 data bytes remain (not counting xmm7), fold the 16 bytes |
| # xmm7 into them, storing the result back into xmm7. |
| jl .Lfold_16_bytes_loop_done |
| .Lfold_16_bytes_loop: |
| movdqa %xmm7, %xmm8 |
| pclmulqdq $0x11, FOLD_CONSTS, %xmm7 |
| pclmulqdq $0x00, FOLD_CONSTS, %xmm8 |
| pxor %xmm8, %xmm7 |
| movdqu (buf), %xmm0 |
| pshufb BSWAP_MASK, %xmm0 |
| pxor %xmm0 , %xmm7 |
| add $16, buf |
| sub $16, len |
| jge .Lfold_16_bytes_loop |
| |
| .Lfold_16_bytes_loop_done: |
| # Add 16 to get the correct number of data bytes remaining in 0...15 |
| # (not counting xmm7), following the previous extra subtraction by 16. |
| add $16, len |
| je .Lreduce_final_16_bytes |
| |
| .Lhandle_partial_segment: |
| # Reduce the last '16 + len' bytes where 1 <= len <= 15 and the first 16 |
| # bytes are in xmm7 and the rest are the remaining data in 'buf'. To do |
| # this without needing a fold constant for each possible 'len', redivide |
| # the bytes into a first chunk of 'len' bytes and a second chunk of 16 |
| # bytes, then fold the first chunk into the second. |
| |
| movdqa %xmm7, %xmm2 |
| |
| # xmm1 = last 16 original data bytes |
| movdqu -16(buf, len), %xmm1 |
| pshufb BSWAP_MASK, %xmm1 |
| |
| # xmm2 = high order part of second chunk: xmm7 left-shifted by 'len' bytes. |
| lea .Lbyteshift_table+16(%rip), %rax |
| sub len, %rax |
| movdqu (%rax), %xmm0 |
| pshufb %xmm0, %xmm2 |
| |
| # xmm7 = first chunk: xmm7 right-shifted by '16-len' bytes. |
| pxor .Lmask1(%rip), %xmm0 |
| pshufb %xmm0, %xmm7 |
| |
| # xmm1 = second chunk: 'len' bytes from xmm1 (low-order bytes), |
| # then '16-len' bytes from xmm2 (high-order bytes). |
| pblendvb %xmm2, %xmm1 #xmm0 is implicit |
| |
| # Fold the first chunk into the second chunk, storing the result in xmm7. |
| movdqa %xmm7, %xmm8 |
| pclmulqdq $0x11, FOLD_CONSTS, %xmm7 |
| pclmulqdq $0x00, FOLD_CONSTS, %xmm8 |
| pxor %xmm8, %xmm7 |
| pxor %xmm1, %xmm7 |
| |
| .Lreduce_final_16_bytes: |
| # Reduce the 128-bit value M(x), stored in xmm7, to the final 16-bit CRC |
| |
| # Load 'x^48 * (x^48 mod G(x))' and 'x^48 * (x^80 mod G(x))'. |
| movdqa .Lfinal_fold_consts(%rip), FOLD_CONSTS |
| |
| # Fold the high 64 bits into the low 64 bits, while also multiplying by |
| # x^64. This produces a 128-bit value congruent to x^64 * M(x) and |
| # whose low 48 bits are 0. |
| movdqa %xmm7, %xmm0 |
| pclmulqdq $0x11, FOLD_CONSTS, %xmm7 # high bits * x^48 * (x^80 mod G(x)) |
| pslldq $8, %xmm0 |
| pxor %xmm0, %xmm7 # + low bits * x^64 |
| |
| # Fold the high 32 bits into the low 96 bits. This produces a 96-bit |
| # value congruent to x^64 * M(x) and whose low 48 bits are 0. |
| movdqa %xmm7, %xmm0 |
| pand .Lmask2(%rip), %xmm0 # zero high 32 bits |
| psrldq $12, %xmm7 # extract high 32 bits |
| pclmulqdq $0x00, FOLD_CONSTS, %xmm7 # high 32 bits * x^48 * (x^48 mod G(x)) |
| pxor %xmm0, %xmm7 # + low bits |
| |
| # Load G(x) and floor(x^48 / G(x)). |
| movdqa .Lbarrett_reduction_consts(%rip), FOLD_CONSTS |
| |
| # Use Barrett reduction to compute the final CRC value. |
| movdqa %xmm7, %xmm0 |
| pclmulqdq $0x11, FOLD_CONSTS, %xmm7 # high 32 bits * floor(x^48 / G(x)) |
| psrlq $32, %xmm7 # /= x^32 |
| pclmulqdq $0x00, FOLD_CONSTS, %xmm7 # *= G(x) |
| psrlq $48, %xmm0 |
| pxor %xmm7, %xmm0 # + low 16 nonzero bits |
| # Final CRC value (x^16 * M(x)) mod G(x) is in low 16 bits of xmm0. |
| |
| pextrw $0, %xmm0, %eax |
| RET |
| |
| .align 16 |
| .Lless_than_256_bytes: |
| # Checksumming a buffer of length 16...255 bytes |
| |
| # Load the first 16 data bytes. |
| movdqu (buf), %xmm7 |
| pshufb BSWAP_MASK, %xmm7 |
| add $16, buf |
| |
| # XOR the first 16 data *bits* with the initial CRC value. |
| pxor %xmm0, %xmm0 |
| pinsrw $7, init_crc, %xmm0 |
| pxor %xmm0, %xmm7 |
| |
| movdqa .Lfold_across_16_bytes_consts(%rip), FOLD_CONSTS |
| cmp $16, len |
| je .Lreduce_final_16_bytes # len == 16 |
| sub $32, len |
| jge .Lfold_16_bytes_loop # 32 <= len <= 255 |
| add $16, len |
| jmp .Lhandle_partial_segment # 17 <= len <= 31 |
| SYM_FUNC_END(crc_t10dif_pcl) |
| |
| .section .rodata, "a", @progbits |
| .align 16 |
| |
| # Fold constants precomputed from the polynomial 0x18bb7 |
| # G(x) = x^16 + x^15 + x^11 + x^9 + x^8 + x^7 + x^5 + x^4 + x^2 + x^1 + x^0 |
| .Lfold_across_128_bytes_consts: |
| .quad 0x0000000000006123 # x^(8*128) mod G(x) |
| .quad 0x0000000000002295 # x^(8*128+64) mod G(x) |
| .Lfold_across_64_bytes_consts: |
| .quad 0x0000000000001069 # x^(4*128) mod G(x) |
| .quad 0x000000000000dd31 # x^(4*128+64) mod G(x) |
| .Lfold_across_32_bytes_consts: |
| .quad 0x000000000000857d # x^(2*128) mod G(x) |
| .quad 0x0000000000007acc # x^(2*128+64) mod G(x) |
| .Lfold_across_16_bytes_consts: |
| .quad 0x000000000000a010 # x^(1*128) mod G(x) |
| .quad 0x0000000000001faa # x^(1*128+64) mod G(x) |
| .Lfinal_fold_consts: |
| .quad 0x1368000000000000 # x^48 * (x^48 mod G(x)) |
| .quad 0x2d56000000000000 # x^48 * (x^80 mod G(x)) |
| .Lbarrett_reduction_consts: |
| .quad 0x0000000000018bb7 # G(x) |
| .quad 0x00000001f65a57f8 # floor(x^48 / G(x)) |
| |
| .section .rodata.cst16.mask1, "aM", @progbits, 16 |
| .align 16 |
| .Lmask1: |
| .octa 0x80808080808080808080808080808080 |
| |
| .section .rodata.cst16.mask2, "aM", @progbits, 16 |
| .align 16 |
| .Lmask2: |
| .octa 0x00000000FFFFFFFFFFFFFFFFFFFFFFFF |
| |
| .section .rodata.cst16.bswap_mask, "aM", @progbits, 16 |
| .align 16 |
| .Lbswap_mask: |
| .octa 0x000102030405060708090A0B0C0D0E0F |
| |
| .section .rodata.cst32.byteshift_table, "aM", @progbits, 32 |
| .align 16 |
| # For 1 <= len <= 15, the 16-byte vector beginning at &byteshift_table[16 - len] |
| # is the index vector to shift left by 'len' bytes, and is also {0x80, ..., |
| # 0x80} XOR the index vector to shift right by '16 - len' bytes. |
| .Lbyteshift_table: |
| .byte 0x0, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87 |
| .byte 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f |
| .byte 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7 |
| .byte 0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe , 0x0 |
