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Diffstat (limited to 'arch/x86/lib/crc-pclmul-template.S')
| -rw-r--r-- | arch/x86/lib/crc-pclmul-template.S | 582 |
1 files changed, 0 insertions, 582 deletions
diff --git a/arch/x86/lib/crc-pclmul-template.S b/arch/x86/lib/crc-pclmul-template.S deleted file mode 100644 index ae0b6144c503..000000000000 --- a/arch/x86/lib/crc-pclmul-template.S +++ /dev/null @@ -1,582 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0-or-later */ -// -// Template to generate [V]PCLMULQDQ-based CRC functions for x86 -// -// Copyright 2025 Google LLC -// -// Author: Eric Biggers <ebiggers@google.com> - -#include <linux/linkage.h> -#include <linux/objtool.h> - -// Offsets within the generated constants table -.set OFFSETOF_BSWAP_MASK, -5*16 // msb-first CRCs only -.set OFFSETOF_FOLD_ACROSS_2048_BITS_CONSTS, -4*16 // must precede next -.set OFFSETOF_FOLD_ACROSS_1024_BITS_CONSTS, -3*16 // must precede next -.set OFFSETOF_FOLD_ACROSS_512_BITS_CONSTS, -2*16 // must precede next -.set OFFSETOF_FOLD_ACROSS_256_BITS_CONSTS, -1*16 // must precede next -.set OFFSETOF_FOLD_ACROSS_128_BITS_CONSTS, 0*16 // must be 0 -.set OFFSETOF_SHUF_TABLE, 1*16 -.set OFFSETOF_BARRETT_REDUCTION_CONSTS, 4*16 - -// Emit a VEX (or EVEX) coded instruction if allowed, or emulate it using the -// corresponding non-VEX instruction plus any needed moves. The supported -// instruction formats are: -// -// - Two-arg [src, dst], where the non-VEX format is the same. -// - Three-arg [src1, src2, dst] where the non-VEX format is -// [src1, src2_and_dst]. If src2 != dst, then src1 must != dst too. -// -// \insn gives the instruction without a "v" prefix and including any immediate -// argument if needed to make the instruction follow one of the above formats. -// If \unaligned_mem_tmp is given, then the emitted non-VEX code moves \arg1 to -// it first; this is needed when \arg1 is an unaligned mem operand. -.macro _cond_vex insn:req, arg1:req, arg2:req, arg3, unaligned_mem_tmp -.if AVX_LEVEL == 0 - // VEX not allowed. Emulate it. - .ifnb \arg3 // Three-arg [src1, src2, dst] - .ifc "\arg2", "\arg3" // src2 == dst? - .ifnb \unaligned_mem_tmp - movdqu \arg1, \unaligned_mem_tmp - \insn \unaligned_mem_tmp, \arg3 - .else - \insn \arg1, \arg3 - .endif - .else // src2 != dst - .ifc "\arg1", "\arg3" - .error "Can't have src1 == dst when src2 != dst" - .endif - .ifnb \unaligned_mem_tmp - movdqu \arg1, \unaligned_mem_tmp - movdqa \arg2, \arg3 - \insn \unaligned_mem_tmp, \arg3 - .else - movdqa \arg2, \arg3 - \insn \arg1, \arg3 - .endif - .endif - .else // Two-arg [src, dst] - .ifnb \unaligned_mem_tmp - movdqu \arg1, \unaligned_mem_tmp - \insn \unaligned_mem_tmp, \arg2 - .else - \insn \arg1, \arg2 - .endif - .endif -.else - // VEX is allowed. Emit the desired instruction directly. - .ifnb \arg3 - v\insn \arg1, \arg2, \arg3 - .else - v\insn \arg1, \arg2 - .endif -.endif -.endm - -// Broadcast an aligned 128-bit mem operand to all 128-bit lanes of a vector -// register of length VL. -.macro _vbroadcast src, dst -.if VL == 16 - _cond_vex movdqa, \src, \dst -.elseif VL == 32 - vbroadcasti128 \src, \dst -.else - vbroadcasti32x4 \src, \dst -.endif -.endm - -// Load \vl bytes from the unaligned mem operand \src into \dst, and if the CRC -// is msb-first use \bswap_mask to reflect the bytes within each 128-bit lane. -.macro _load_data vl, src, bswap_mask, dst -.if \vl < 64 - _cond_vex movdqu, "\src", \dst -.else - vmovdqu8 \src, \dst -.endif -.if !LSB_CRC - _cond_vex pshufb, \bswap_mask, \dst, \dst -.endif -.endm - -.macro _prepare_v0 vl, v0, v1, bswap_mask -.if LSB_CRC - .if \vl < 64 - _cond_vex pxor, (BUF), \v0, \v0, unaligned_mem_tmp=\v1 - .else - vpxorq (BUF), \v0, \v0 - .endif -.else - _load_data \vl, (BUF), \bswap_mask, \v1 - .if \vl < 64 - _cond_vex pxor, \v1, \v0, \v0 - .else - vpxorq \v1, \v0, \v0 - .endif -.endif -.endm - -// The x^0..x^63 terms, i.e. poly128 mod x^64, i.e. the physically low qword for -// msb-first order or the physically high qword for lsb-first order -#define LO64_TERMS 0 - -// The x^64..x^127 terms, i.e. floor(poly128 / x^64), i.e. the physically high -// qword for msb-first order or the physically low qword for lsb-first order -#define HI64_TERMS 1 - -// Multiply the given \src1_terms of each 128-bit lane of \src1 by the given -// \src2_terms of each 128-bit lane of \src2, and write the result(s) to \dst. -.macro _pclmulqdq src1, src1_terms, src2, src2_terms, dst - _cond_vex "pclmulqdq $((\src1_terms ^ LSB_CRC) << 4) ^ (\src2_terms ^ LSB_CRC),", \ - \src1, \src2, \dst -.endm - -// Fold \acc into \data and store the result back into \acc. \data can be an -// unaligned mem operand if using VEX is allowed and the CRC is lsb-first so no -// byte-reflection is needed; otherwise it must be a vector register. \consts -// is a vector register containing the needed fold constants, and \tmp is a -// temporary vector register. All arguments must be the same length. -.macro _fold_vec acc, data, consts, tmp - _pclmulqdq \consts, HI64_TERMS, \acc, HI64_TERMS, \tmp - _pclmulqdq \consts, LO64_TERMS, \acc, LO64_TERMS, \acc -.if AVX_LEVEL <= 2 - _cond_vex pxor, \data, \tmp, \tmp - _cond_vex pxor, \tmp, \acc, \acc -.else - vpternlogq $0x96, \data, \tmp, \acc -.endif -.endm - -// Fold \acc into \data and store the result back into \acc. \data is an -// unaligned mem operand, \consts is a vector register containing the needed -// fold constants, \bswap_mask is a vector register containing the -// byte-reflection table if the CRC is msb-first, and \tmp1 and \tmp2 are -// temporary vector registers. All arguments must have length \vl. -.macro _fold_vec_mem vl, acc, data, consts, bswap_mask, tmp1, tmp2 -.if AVX_LEVEL == 0 || !LSB_CRC - _load_data \vl, \data, \bswap_mask, \tmp1 - _fold_vec \acc, \tmp1, \consts, \tmp2 -.else - _fold_vec \acc, \data, \consts, \tmp1 -.endif -.endm - -// Load the constants for folding across 2**i vectors of length VL at a time -// into all 128-bit lanes of the vector register CONSTS. -.macro _load_vec_folding_consts i - _vbroadcast OFFSETOF_FOLD_ACROSS_128_BITS_CONSTS+(4-LOG2_VL-\i)*16(CONSTS_PTR), \ - CONSTS -.endm - -// Given vector registers \v0 and \v1 of length \vl, fold \v0 into \v1 and store -// the result back into \v0. If the remaining length mod \vl is nonzero, also -// fold \vl data bytes from BUF. For both operations the fold distance is \vl. -// \consts must be a register of length \vl containing the fold constants. -.macro _fold_vec_final vl, v0, v1, consts, bswap_mask, tmp1, tmp2 - _fold_vec \v0, \v1, \consts, \tmp1 - test $\vl, LEN8 - jz .Lfold_vec_final_done\@ - _fold_vec_mem \vl, \v0, (BUF), \consts, \bswap_mask, \tmp1, \tmp2 - add $\vl, BUF -.Lfold_vec_final_done\@: -.endm - -// This macro generates the body of a CRC function with the following prototype: -// -// crc_t crc_func(crc_t crc, const u8 *buf, size_t len, const void *consts); -// -// |crc| is the initial CRC, and crc_t is a data type wide enough to hold it. -// |buf| is the data to checksum. |len| is the data length in bytes, which must -// be at least 16. |consts| is a pointer to the fold_across_128_bits_consts -// field of the constants struct that was generated for the chosen CRC variant. -// -// Moving onto the macro parameters, \n is the number of bits in the CRC, e.g. -// 32 for a CRC-32. Currently the supported values are 8, 16, 32, and 64. If -// the file is compiled in i386 mode, then the maximum supported value is 32. -// -// \lsb_crc is 1 if the CRC processes the least significant bit of each byte -// first, i.e. maps bit0 to x^7, bit1 to x^6, ..., bit7 to x^0. \lsb_crc is 0 -// if the CRC processes the most significant bit of each byte first, i.e. maps -// bit0 to x^0, bit1 to x^1, bit7 to x^7. -// -// \vl is the maximum length of vector register to use in bytes: 16, 32, or 64. -// -// \avx_level is the level of AVX support to use: 0 for SSE only, 2 for AVX2, or -// 512 for AVX512. -// -// If \vl == 16 && \avx_level == 0, the generated code requires: -// PCLMULQDQ && SSE4.1. (Note: all known CPUs with PCLMULQDQ also have SSE4.1.) -// -// If \vl == 32 && \avx_level == 2, the generated code requires: -// VPCLMULQDQ && AVX2. -// -// If \vl == 64 && \avx_level == 512, the generated code requires: -// VPCLMULQDQ && AVX512BW && AVX512VL. -// -// Other \vl and \avx_level combinations are either not supported or not useful. -.macro _crc_pclmul n, lsb_crc, vl, avx_level - .set LSB_CRC, \lsb_crc - .set VL, \vl - .set AVX_LEVEL, \avx_level - - // Define aliases for the xmm, ymm, or zmm registers according to VL. -.irp i, 0,1,2,3,4,5,6,7 - .if VL == 16 - .set V\i, %xmm\i - .set LOG2_VL, 4 - .elseif VL == 32 - .set V\i, %ymm\i - .set LOG2_VL, 5 - .elseif VL == 64 - .set V\i, %zmm\i - .set LOG2_VL, 6 - .else - .error "Unsupported vector length" - .endif -.endr - // Define aliases for the function parameters. - // Note: when crc_t is shorter than u32, zero-extension to 32 bits is - // guaranteed by the ABI. Zero-extension to 64 bits is *not* guaranteed - // when crc_t is shorter than u64. -#ifdef __x86_64__ -.if \n <= 32 - .set CRC, %edi -.else - .set CRC, %rdi -.endif - .set BUF, %rsi - .set LEN, %rdx - .set LEN32, %edx - .set LEN8, %dl - .set CONSTS_PTR, %rcx -#else - // 32-bit support, assuming -mregparm=3 and not including support for - // CRC-64 (which would use both eax and edx to pass the crc parameter). - .set CRC, %eax - .set BUF, %edx - .set LEN, %ecx - .set LEN32, %ecx - .set LEN8, %cl - .set CONSTS_PTR, %ebx // Passed on stack -#endif - - // Define aliases for some local variables. V0-V5 are used without - // aliases (for accumulators, data, temporary values, etc). Staying - // within the first 8 vector registers keeps the code 32-bit SSE - // compatible and reduces the size of 64-bit SSE code slightly. - .set BSWAP_MASK, V6 - .set BSWAP_MASK_YMM, %ymm6 - .set BSWAP_MASK_XMM, %xmm6 - .set CONSTS, V7 - .set CONSTS_YMM, %ymm7 - .set CONSTS_XMM, %xmm7 - - // Use ANNOTATE_NOENDBR to suppress an objtool warning, since the - // functions generated by this macro are called only by static_call. - ANNOTATE_NOENDBR - -#ifdef __i386__ - push CONSTS_PTR - mov 8(%esp), CONSTS_PTR -#endif - - // Create a 128-bit vector that contains the initial CRC in the end - // representing the high-order polynomial coefficients, and the rest 0. - // If the CRC is msb-first, also load the byte-reflection table. -.if \n <= 32 - _cond_vex movd, CRC, %xmm0 -.else - _cond_vex movq, CRC, %xmm0 -.endif -.if !LSB_CRC - _cond_vex pslldq, $(128-\n)/8, %xmm0, %xmm0 - _vbroadcast OFFSETOF_BSWAP_MASK(CONSTS_PTR), BSWAP_MASK -.endif - - // Load the first vector of data and XOR the initial CRC into the - // appropriate end of the first 128-bit lane of data. If LEN < VL, then - // use a short vector and jump ahead to the final reduction. (LEN >= 16 - // is guaranteed here but not necessarily LEN >= VL.) -.if VL >= 32 - cmp $VL, LEN - jae .Lat_least_1vec\@ - .if VL == 64 - cmp $32, LEN32 - jb .Lless_than_32bytes\@ - _prepare_v0 32, %ymm0, %ymm1, BSWAP_MASK_YMM - add $32, BUF - jmp .Lreduce_256bits_to_128bits\@ -.Lless_than_32bytes\@: - .endif - _prepare_v0 16, %xmm0, %xmm1, BSWAP_MASK_XMM - add $16, BUF - vmovdqa OFFSETOF_FOLD_ACROSS_128_BITS_CONSTS(CONSTS_PTR), CONSTS_XMM - jmp .Lcheck_for_partial_block\@ -.Lat_least_1vec\@: -.endif - _prepare_v0 VL, V0, V1, BSWAP_MASK - - // Handle VL <= LEN < 4*VL. - cmp $4*VL-1, LEN - ja .Lat_least_4vecs\@ - add $VL, BUF - // If VL <= LEN < 2*VL, then jump ahead to the reduction from 1 vector. - // If VL==16 then load fold_across_128_bits_consts first, as the final - // reduction depends on it and it won't be loaded anywhere else. - cmp $2*VL-1, LEN32 -.if VL == 16 - _cond_vex movdqa, OFFSETOF_FOLD_ACROSS_128_BITS_CONSTS(CONSTS_PTR), CONSTS_XMM -.endif - jbe .Lreduce_1vec_to_128bits\@ - // Otherwise 2*VL <= LEN < 4*VL. Load one more vector and jump ahead to - // the reduction from 2 vectors. - _load_data VL, (BUF), BSWAP_MASK, V1 - add $VL, BUF - jmp .Lreduce_2vecs_to_1\@ - -.Lat_least_4vecs\@: - // Load 3 more vectors of data. - _load_data VL, 1*VL(BUF), BSWAP_MASK, V1 - _load_data VL, 2*VL(BUF), BSWAP_MASK, V2 - _load_data VL, 3*VL(BUF), BSWAP_MASK, V3 - sub $-4*VL, BUF // Shorter than 'add 4*VL' when VL=32 - add $-4*VL, LEN // Shorter than 'sub 4*VL' when VL=32 - - // Main loop: while LEN >= 4*VL, fold the 4 vectors V0-V3 into the next - // 4 vectors of data and write the result back to V0-V3. - cmp $4*VL-1, LEN // Shorter than 'cmp 4*VL' when VL=32 - jbe .Lreduce_4vecs_to_2\@ - _load_vec_folding_consts 2 -.Lfold_4vecs_loop\@: - _fold_vec_mem VL, V0, 0*VL(BUF), CONSTS, BSWAP_MASK, V4, V5 - _fold_vec_mem VL, V1, 1*VL(BUF), CONSTS, BSWAP_MASK, V4, V5 - _fold_vec_mem VL, V2, 2*VL(BUF), CONSTS, BSWAP_MASK, V4, V5 - _fold_vec_mem VL, V3, 3*VL(BUF), CONSTS, BSWAP_MASK, V4, V5 - sub $-4*VL, BUF - add $-4*VL, LEN - cmp $4*VL-1, LEN - ja .Lfold_4vecs_loop\@ - - // Fold V0,V1 into V2,V3 and write the result back to V0,V1. Then fold - // two more vectors of data from BUF, if at least that much remains. -.Lreduce_4vecs_to_2\@: - _load_vec_folding_consts 1 - _fold_vec V0, V2, CONSTS, V4 - _fold_vec V1, V3, CONSTS, V4 - test $2*VL, LEN8 - jz .Lreduce_2vecs_to_1\@ - _fold_vec_mem VL, V0, 0*VL(BUF), CONSTS, BSWAP_MASK, V4, V5 - _fold_vec_mem VL, V1, 1*VL(BUF), CONSTS, BSWAP_MASK, V4, V5 - sub $-2*VL, BUF - - // Fold V0 into V1 and write the result back to V0. Then fold one more - // vector of data from BUF, if at least that much remains. -.Lreduce_2vecs_to_1\@: - _load_vec_folding_consts 0 - _fold_vec_final VL, V0, V1, CONSTS, BSWAP_MASK, V4, V5 - -.Lreduce_1vec_to_128bits\@: -.if VL == 64 - // Reduce 512-bit %zmm0 to 256-bit %ymm0. Then fold 256 more bits of - // data from BUF, if at least that much remains. - vbroadcasti128 OFFSETOF_FOLD_ACROSS_256_BITS_CONSTS(CONSTS_PTR), CONSTS_YMM - vextracti64x4 $1, %zmm0, %ymm1 - _fold_vec_final 32, %ymm0, %ymm1, CONSTS_YMM, BSWAP_MASK_YMM, %ymm4, %ymm5 -.Lreduce_256bits_to_128bits\@: -.endif -.if VL >= 32 - // Reduce 256-bit %ymm0 to 128-bit %xmm0. Then fold 128 more bits of - // data from BUF, if at least that much remains. - vmovdqa OFFSETOF_FOLD_ACROSS_128_BITS_CONSTS(CONSTS_PTR), CONSTS_XMM - vextracti128 $1, %ymm0, %xmm1 - _fold_vec_final 16, %xmm0, %xmm1, CONSTS_XMM, BSWAP_MASK_XMM, %xmm4, %xmm5 -.Lcheck_for_partial_block\@: -.endif - and $15, LEN32 - jz .Lreduce_128bits_to_crc\@ - - // 1 <= LEN <= 15 data bytes remain in BUF. The polynomial is now - // A*(x^(8*LEN)) + B, where A is the 128-bit polynomial stored in %xmm0 - // and B is the polynomial of the remaining LEN data bytes. To reduce - // this to 128 bits without needing fold constants for each possible - // LEN, rearrange this expression into C1*(x^128) + C2, where - // C1 = floor(A / x^(128 - 8*LEN)) and C2 = A*x^(8*LEN) + B mod x^128. - // Then fold C1 into C2, which is just another fold across 128 bits. - -.if !LSB_CRC || AVX_LEVEL == 0 - // Load the last 16 data bytes. Note that originally LEN was >= 16. - _load_data 16, "-16(BUF,LEN)", BSWAP_MASK_XMM, %xmm2 -.endif // Else will use vpblendvb mem operand later. -.if !LSB_CRC - neg LEN // Needed for indexing shuf_table -.endif - - // tmp = A*x^(8*LEN) mod x^128 - // lsb: pshufb by [LEN, LEN+1, ..., 15, -1, -1, ..., -1] - // i.e. right-shift by LEN bytes. - // msb: pshufb by [-1, -1, ..., -1, 0, 1, ..., 15-LEN] - // i.e. left-shift by LEN bytes. - _cond_vex movdqu, "OFFSETOF_SHUF_TABLE+16(CONSTS_PTR,LEN)", %xmm3 - _cond_vex pshufb, %xmm3, %xmm0, %xmm1 - - // C1 = floor(A / x^(128 - 8*LEN)) - // lsb: pshufb by [-1, -1, ..., -1, 0, 1, ..., LEN-1] - // i.e. left-shift by 16-LEN bytes. - // msb: pshufb by [16-LEN, 16-LEN+1, ..., 15, -1, -1, ..., -1] - // i.e. right-shift by 16-LEN bytes. - _cond_vex pshufb, "OFFSETOF_SHUF_TABLE+32*!LSB_CRC(CONSTS_PTR,LEN)", \ - %xmm0, %xmm0, unaligned_mem_tmp=%xmm4 - - // C2 = tmp + B. This is just a blend of tmp with the last 16 data - // bytes (reflected if msb-first). The blend mask is the shuffle table - // that was used to create tmp. 0 selects tmp, and 1 last16databytes. -.if AVX_LEVEL == 0 - movdqa %xmm0, %xmm4 - movdqa %xmm3, %xmm0 - pblendvb %xmm2, %xmm1 // uses %xmm0 as implicit operand - movdqa %xmm4, %xmm0 -.elseif LSB_CRC - vpblendvb %xmm3, -16(BUF,LEN), %xmm1, %xmm1 -.else - vpblendvb %xmm3, %xmm2, %xmm1, %xmm1 -.endif - - // Fold C1 into C2 and store the 128-bit result in %xmm0. - _fold_vec %xmm0, %xmm1, CONSTS_XMM, %xmm4 - -.Lreduce_128bits_to_crc\@: - // Compute the CRC as %xmm0 * x^n mod G. Here %xmm0 means the 128-bit - // polynomial stored in %xmm0 (using either lsb-first or msb-first bit - // order according to LSB_CRC), and G is the CRC's generator polynomial. - - // First, multiply %xmm0 by x^n and reduce the result to 64+n bits: - // - // t0 := (x^(64+n) mod G) * floor(%xmm0 / x^64) + - // x^n * (%xmm0 mod x^64) - // - // Store t0 * x^(64-n) in %xmm0. I.e., actually do: - // - // %xmm0 := ((x^(64+n) mod G) * x^(64-n)) * floor(%xmm0 / x^64) + - // x^64 * (%xmm0 mod x^64) - // - // The extra unreduced factor of x^(64-n) makes floor(t0 / x^n) aligned - // to the HI64_TERMS of %xmm0 so that the next pclmulqdq can easily - // select it. The 64-bit constant (x^(64+n) mod G) * x^(64-n) in the - // msb-first case, or (x^(63+n) mod G) * x^(64-n) in the lsb-first case - // (considering the extra factor of x that gets implicitly introduced by - // each pclmulqdq when using lsb-first order), is identical to the - // constant that was used earlier for folding the LO64_TERMS across 128 - // bits. Thus it's already available in LO64_TERMS of CONSTS_XMM. - _pclmulqdq CONSTS_XMM, LO64_TERMS, %xmm0, HI64_TERMS, %xmm1 -.if LSB_CRC - _cond_vex psrldq, $8, %xmm0, %xmm0 // x^64 * (%xmm0 mod x^64) -.else - _cond_vex pslldq, $8, %xmm0, %xmm0 // x^64 * (%xmm0 mod x^64) -.endif - _cond_vex pxor, %xmm1, %xmm0, %xmm0 - // The HI64_TERMS of %xmm0 now contain floor(t0 / x^n). - // The LO64_TERMS of %xmm0 now contain (t0 mod x^n) * x^(64-n). - - // First step of Barrett reduction: Compute floor(t0 / G). This is the - // polynomial by which G needs to be multiplied to cancel out the x^n - // and higher terms of t0, i.e. to reduce t0 mod G. First do: - // - // t1 := floor(x^(63+n) / G) * x * floor(t0 / x^n) - // - // Then the desired value floor(t0 / G) is floor(t1 / x^64). The 63 in - // x^(63+n) is the maximum degree of floor(t0 / x^n) and thus the lowest - // value that makes enough precision be carried through the calculation. - // - // The '* x' makes it so the result is floor(t1 / x^64) rather than - // floor(t1 / x^63), making it qword-aligned in HI64_TERMS so that it - // can be extracted much more easily in the next step. In the lsb-first - // case the '* x' happens implicitly. In the msb-first case it must be - // done explicitly; floor(x^(63+n) / G) * x is a 65-bit constant, so the - // constant passed to pclmulqdq is (floor(x^(63+n) / G) * x) - x^64, and - // the multiplication by the x^64 term is handled using a pxor. The - // pxor causes the low 64 terms of t1 to be wrong, but they are unused. - _cond_vex movdqa, OFFSETOF_BARRETT_REDUCTION_CONSTS(CONSTS_PTR), CONSTS_XMM - _pclmulqdq CONSTS_XMM, HI64_TERMS, %xmm0, HI64_TERMS, %xmm1 -.if !LSB_CRC - _cond_vex pxor, %xmm0, %xmm1, %xmm1 // += x^64 * floor(t0 / x^n) -.endif - // The HI64_TERMS of %xmm1 now contain floor(t1 / x^64) = floor(t0 / G). - - // Second step of Barrett reduction: Cancel out the x^n and higher terms - // of t0 by subtracting the needed multiple of G. This gives the CRC: - // - // crc := t0 - (G * floor(t0 / G)) - // - // But %xmm0 contains t0 * x^(64-n), so it's more convenient to do: - // - // crc := ((t0 * x^(64-n)) - ((G * x^(64-n)) * floor(t0 / G))) / x^(64-n) - // - // Furthermore, since the resulting CRC is n-bit, if mod x^n is - // explicitly applied to it then the x^n term of G makes no difference - // in the result and can be omitted. This helps keep the constant - // multiplier in 64 bits in most cases. This gives the following: - // - // %xmm0 := %xmm0 - (((G - x^n) * x^(64-n)) * floor(t0 / G)) - // crc := (%xmm0 / x^(64-n)) mod x^n - // - // In the lsb-first case, each pclmulqdq implicitly introduces - // an extra factor of x, so in that case the constant that needs to be - // passed to pclmulqdq is actually '(G - x^n) * x^(63-n)' when n <= 63. - // For lsb-first CRCs where n=64, the extra factor of x cannot be as - // easily avoided. In that case, instead pass '(G - x^n - x^0) / x' to - // pclmulqdq and handle the x^0 term (i.e. 1) separately. (All CRC - // polynomials have nonzero x^n and x^0 terms.) It works out as: the - // CRC has be XORed with the physically low qword of %xmm1, representing - // floor(t0 / G). The most efficient way to do that is to move it to - // the physically high qword and use a ternlog to combine the two XORs. -.if LSB_CRC && \n == 64 - _cond_vex punpcklqdq, %xmm1, %xmm2, %xmm2 - _pclmulqdq CONSTS_XMM, LO64_TERMS, %xmm1, HI64_TERMS, %xmm1 - .if AVX_LEVEL <= 2 - _cond_vex pxor, %xmm2, %xmm0, %xmm0 - _cond_vex pxor, %xmm1, %xmm0, %xmm0 - .else - vpternlogq $0x96, %xmm2, %xmm1, %xmm0 - .endif - _cond_vex "pextrq $1,", %xmm0, %rax // (%xmm0 / x^0) mod x^64 -.else - _pclmulqdq CONSTS_XMM, LO64_TERMS, %xmm1, HI64_TERMS, %xmm1 - _cond_vex pxor, %xmm1, %xmm0, %xmm0 - .if \n == 8 - _cond_vex "pextrb $7 + LSB_CRC,", %xmm0, %eax // (%xmm0 / x^56) mod x^8 - .elseif \n == 16 - _cond_vex "pextrw $3 + LSB_CRC,", %xmm0, %eax // (%xmm0 / x^48) mod x^16 - .elseif \n == 32 - _cond_vex "pextrd $1 + LSB_CRC,", %xmm0, %eax // (%xmm0 / x^32) mod x^32 - .else // \n == 64 && !LSB_CRC - _cond_vex movq, %xmm0, %rax // (%xmm0 / x^0) mod x^64 - .endif -.endif - -.if VL > 16 - vzeroupper // Needed when ymm or zmm registers may have been used. -.endif -#ifdef __i386__ - pop CONSTS_PTR -#endif - RET -.endm - -#ifdef CONFIG_AS_VPCLMULQDQ -#define DEFINE_CRC_PCLMUL_FUNCS(prefix, bits, lsb) \ -SYM_FUNC_START(prefix##_pclmul_sse); \ - _crc_pclmul n=bits, lsb_crc=lsb, vl=16, avx_level=0; \ -SYM_FUNC_END(prefix##_pclmul_sse); \ - \ -SYM_FUNC_START(prefix##_vpclmul_avx2); \ - _crc_pclmul n=bits, lsb_crc=lsb, vl=32, avx_level=2; \ -SYM_FUNC_END(prefix##_vpclmul_avx2); \ - \ -SYM_FUNC_START(prefix##_vpclmul_avx512); \ - _crc_pclmul n=bits, lsb_crc=lsb, vl=64, avx_level=512; \ -SYM_FUNC_END(prefix##_vpclmul_avx512); -#else -#define DEFINE_CRC_PCLMUL_FUNCS(prefix, bits, lsb) \ -SYM_FUNC_START(prefix##_pclmul_sse); \ - _crc_pclmul n=bits, lsb_crc=lsb, vl=16, avx_level=0; \ -SYM_FUNC_END(prefix##_pclmul_sse); -#endif // !CONFIG_AS_VPCLMULQDQ |