crypto: arm64/crct10dif-ce - cleanup and optimizations
authorEric Biggers <ebiggers@google.com>
Thu, 31 Jan 2019 04:42:42 +0000 (20:42 -0800)
committerHerbert Xu <herbert@gondor.apana.org.au>
Fri, 8 Feb 2019 07:29:48 +0000 (15:29 +0800)
The x86, arm, and arm64 asm implementations of crct10dif are very
difficult to understand partly because many of the comments, labels, and
macros are named incorrectly: the lengths mentioned are usually off by a
factor of two from the actual code.  Many other things are unnecessarily
convoluted as well, e.g. there are many more fold constants than
actually needed and some aren't fully reduced.

This series therefore cleans up all these implementations to be much
more maintainable.  I also made some small optimizations where I saw
opportunities, resulting in slightly better performance.

This patch cleans up the arm64 version.

Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
arch/arm64/crypto/crct10dif-ce-core.S
arch/arm64/crypto/crct10dif-ce-glue.c

index f7326259c40deb370e811cd584151895e19fdc96..e545b42e6a468aa296f8428aaabedc01156b9395 100644 (file)
@@ -2,12 +2,14 @@
 // Accelerated CRC-T10DIF using arm64 NEON and Crypto Extensions instructions
 //
 // Copyright (C) 2016 Linaro Ltd <ard.biesheuvel@linaro.org>
+// Copyright (C) 2019 Google LLC <ebiggers@google.com>
 //
 // This program is free software; you can redistribute it and/or modify
 // it under the terms of the GNU General Public License version 2 as
 // published by the Free Software Foundation.
 //
 
+// Derived from the x86 version:
 //
 // Implement fast CRC-T10DIF computation with SSE and PCLMULQDQ instructions
 //
 // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 //
-//       Function API:
-//       UINT16 crc_t10dif_pcl(
-//               UINT16 init_crc, //initial CRC value, 16 bits
-//               const unsigned char *buf, //buffer pointer to calculate CRC on
-//               UINT64 len //buffer length in bytes (64-bit data)
-//       );
-//
 //       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>
 #include <asm/assembler.h>
        .text
        .cpu            generic+crypto
 
-       arg1_low32      .req    w19
-       arg2            .req    x20
-       arg3            .req    x21
+       init_crc        .req    w19
+       buf             .req    x20
+       len             .req    x21
+       fold_consts_ptr .req    x22
 
-       vzr             .req    v13
+       fold_consts     .req    v10
 
        ad              .req    v14
-       bd              .req    v10
 
        k00_16          .req    v15
        k32_48          .req    v16
@@ -143,11 +137,11 @@ __pmull_p8_core:
        ext             t5.8b, ad.8b, ad.8b, #2                 // A2
        ext             t6.8b, ad.8b, ad.8b, #3                 // A3
 
-       pmull           t4.8h, t4.8b, bd.8b                     // F = A1*B
+       pmull           t4.8h, t4.8b, fold_consts.8b            // F = A1*B
        pmull           t8.8h, ad.8b, bd1.8b                    // E = A*B1
-       pmull           t5.8h, t5.8b, bd.8b                     // H = A2*B
+       pmull           t5.8h, t5.8b, fold_consts.8b            // H = A2*B
        pmull           t7.8h, ad.8b, bd2.8b                    // G = A*B2
-       pmull           t6.8h, t6.8b, bd.8b                     // J = A3*B
+       pmull           t6.8h, t6.8b, fold_consts.8b            // J = A3*B
        pmull           t9.8h, ad.8b, bd3.8b                    // I = A*B3
        pmull           t3.8h, ad.8b, bd4.8b                    // K = A*B4
        b               0f
@@ -157,11 +151,11 @@ __pmull_p8_core:
        tbl             t5.16b, {ad.16b}, perm2.16b             // A2
        tbl             t6.16b, {ad.16b}, perm3.16b             // A3
 
-       pmull2          t4.8h, t4.16b, bd.16b                   // F = A1*B
+       pmull2          t4.8h, t4.16b, fold_consts.16b          // F = A1*B
        pmull2          t8.8h, ad.16b, bd1.16b                  // E = A*B1
-       pmull2          t5.8h, t5.16b, bd.16b                   // H = A2*B
+       pmull2          t5.8h, t5.16b, fold_consts.16b          // H = A2*B
        pmull2          t7.8h, ad.16b, bd2.16b                  // G = A*B2
-       pmull2          t6.8h, t6.16b, bd.16b                   // J = A3*B
+       pmull2          t6.8h, t6.16b, fold_consts.16b          // J = A3*B
        pmull2          t9.8h, ad.16b, bd3.16b                  // I = A*B3
        pmull2          t3.8h, ad.16b, bd4.16b                  // K = A*B4
 
@@ -203,14 +197,14 @@ __pmull_p8_core:
 ENDPROC(__pmull_p8_core)
 
        .macro          __pmull_p8, rq, ad, bd, i
-       .ifnc           \bd, v10
+       .ifnc           \bd, fold_consts
        .err
        .endif
        mov             ad.16b, \ad\().16b
        .ifb            \i
-       pmull           \rq\().8h, \ad\().8b, bd.8b             // D = A*B
+       pmull           \rq\().8h, \ad\().8b, \bd\().8b         // D = A*B
        .else
-       pmull2          \rq\().8h, \ad\().16b, bd.16b           // D = A*B
+       pmull2          \rq\().8h, \ad\().16b, \bd\().16b       // D = A*B
        .endif
 
        bl              .L__pmull_p8_core\i
@@ -219,17 +213,19 @@ ENDPROC(__pmull_p8_core)
        eor             \rq\().16b, \rq\().16b, t6.16b
        .endm
 
-       .macro          fold64, p, reg1, reg2
-       ldp             q11, q12, [arg2], #0x20
+       // Fold reg1, reg2 into the next 32 data bytes, storing the result back
+       // into reg1, reg2.
+       .macro          fold_32_bytes, p, reg1, reg2
+       ldp             q11, q12, [buf], #0x20
 
-       __pmull_\p      v8, \reg1, v10, 2
-       __pmull_\p      \reg1, \reg1, v10
+       __pmull_\p      v8, \reg1, fold_consts, 2
+       __pmull_\p      \reg1, \reg1, fold_consts
 
 CPU_LE(        rev64           v11.16b, v11.16b                )
 CPU_LE(        rev64           v12.16b, v12.16b                )
 
-       __pmull_\p      v9, \reg2, v10, 2
-       __pmull_\p      \reg2, \reg2, v10
+       __pmull_\p      v9, \reg2, fold_consts, 2
+       __pmull_\p      \reg2, \reg2, fold_consts
 
 CPU_LE(        ext             v11.16b, v11.16b, v11.16b, #8   )
 CPU_LE(        ext             v12.16b, v12.16b, v12.16b, #8   )
@@ -240,15 +236,16 @@ CPU_LE(   ext             v12.16b, v12.16b, v12.16b, #8   )
        eor             \reg2\().16b, \reg2\().16b, v12.16b
        .endm
 
-       .macro          fold16, p, reg, rk
-       __pmull_\p      v8, \reg, v10
-       __pmull_\p      \reg, \reg, v10, 2
-       .ifnb           \rk
-       ldr_l           q10, \rk, x8
-       __pmull_pre_\p  v10
+       // Fold src_reg into dst_reg, optionally loading the next fold constants
+       .macro          fold_16_bytes, p, src_reg, dst_reg, load_next_consts
+       __pmull_\p      v8, \src_reg, fold_consts
+       __pmull_\p      \src_reg, \src_reg, fold_consts, 2
+       .ifnb           \load_next_consts
+       ld1             {fold_consts.2d}, [fold_consts_ptr], #16
+       __pmull_pre_\p  fold_consts
        .endif
-       eor             v7.16b, v7.16b, v8.16b
-       eor             v7.16b, v7.16b, \reg\().16b
+       eor             \dst_reg\().16b, \dst_reg\().16b, v8.16b
+       eor             \dst_reg\().16b, \dst_reg\().16b, \src_reg\().16b
        .endm
 
        .macro          __pmull_p64, rd, rn, rm, n
@@ -260,40 +257,27 @@ CPU_LE(   ext             v12.16b, v12.16b, v12.16b, #8   )
        .endm
 
        .macro          crc_t10dif_pmull, p
-       frame_push      3, 128
+       frame_push      4, 128
 
-       mov             arg1_low32, w0
-       mov             arg2, x1
-       mov             arg3, x2
-
-       movi            vzr.16b, #0             // init zero register
+       mov             init_crc, w0
+       mov             buf, x1
+       mov             len, x2
 
        __pmull_init_\p
 
-       // adjust the 16-bit initial_crc value, scale it to 32 bits
-       lsl             arg1_low32, arg1_low32, #16
-
-       // check if smaller than 256
-       cmp             arg3, #256
-
-       // for sizes less than 128, we can't fold 64B at a time...
-       b.lt            .L_less_than_128_\@
+       // For sizes less than 256 bytes, we can't fold 128 bytes at a time.
+       cmp             len, #256
+       b.lt            .Lless_than_256_bytes_\@
 
-       // load the initial crc value
-       // crc value does not need to be byte-reflected, but it needs
-       // to be moved to the high part of the register.
-       // because data will be byte-reflected and will align with
-       // initial crc at correct place.
-       movi            v10.16b, #0
-       mov             v10.s[3], arg1_low32            // initial crc
-
-       // receive the initial 64B data, xor the initial crc value
-       ldp             q0, q1, [arg2]
-       ldp             q2, q3, [arg2, #0x20]
-       ldp             q4, q5, [arg2, #0x40]
-       ldp             q6, q7, [arg2, #0x60]
-       add             arg2, arg2, #0x80
+       adr_l           fold_consts_ptr, .Lfold_across_128_bytes_consts
 
+       // Load the first 128 data bytes.  Byte swapping is necessary to make
+       // the bit order match the polynomial coefficient order.
+       ldp             q0, q1, [buf]
+       ldp             q2, q3, [buf, #0x20]
+       ldp             q4, q5, [buf, #0x40]
+       ldp             q6, q7, [buf, #0x60]
+       add             buf, buf, #0x80
 CPU_LE(        rev64           v0.16b, v0.16b                  )
 CPU_LE(        rev64           v1.16b, v1.16b                  )
 CPU_LE(        rev64           v2.16b, v2.16b                  )
@@ -302,7 +286,6 @@ CPU_LE(     rev64           v4.16b, v4.16b                  )
 CPU_LE(        rev64           v5.16b, v5.16b                  )
 CPU_LE(        rev64           v6.16b, v6.16b                  )
 CPU_LE(        rev64           v7.16b, v7.16b                  )
-
 CPU_LE(        ext             v0.16b, v0.16b, v0.16b, #8      )
 CPU_LE(        ext             v1.16b, v1.16b, v1.16b, #8      )
 CPU_LE(        ext             v2.16b, v2.16b, v2.16b, #8      )
@@ -312,36 +295,29 @@ CPU_LE(   ext             v5.16b, v5.16b, v5.16b, #8      )
 CPU_LE(        ext             v6.16b, v6.16b, v6.16b, #8      )
 CPU_LE(        ext             v7.16b, v7.16b, v7.16b, #8      )
 
-       // XOR the initial_crc value
-       eor             v0.16b, v0.16b, v10.16b
-
-       ldr_l           q10, rk3, x8    // xmm10 has rk3 and rk4
-                                       // type of pmull instruction
-                                       // will determine which constant to use
-       __pmull_pre_\p  v10
-
-       //
-       // we subtract 256 instead of 128 to save one instruction from the loop
-       //
-       sub             arg3, arg3, #256
-
-       // at this section of the code, there is 64*x+y (0<=y<64) bytes of
-       // buffer. The _fold_64_B_loop will fold 64B at a time
-       // until we have 64+y Bytes of buffer
+       // XOR the first 16 data *bits* with the initial CRC value.
+       movi            v8.16b, #0
+       mov             v8.h[7], init_crc
+       eor             v0.16b, v0.16b, v8.16b
 
-       // fold 64B at a time. This section of the code folds 4 vector
-       // registers in parallel
-.L_fold_64_B_loop_\@:
+       // Load the constants for folding across 128 bytes.
+       ld1             {fold_consts.2d}, [fold_consts_ptr]
+       __pmull_pre_\p  fold_consts
 
-       fold64          \p, v0, v1
-       fold64          \p, v2, v3
-       fold64          \p, v4, v5
-       fold64          \p, v6, v7
+       // Subtract 128 for the 128 data bytes just consumed.  Subtract another
+       // 128 to simplify the termination condition of the following loop.
+       sub             len, len, #256
 
-       subs            arg3, arg3, #128
+       // While >= 128 data bytes remain (not counting v0-v7), fold the 128
+       // bytes v0-v7 into them, storing the result back into v0-v7.
+.Lfold_128_bytes_loop_\@:
+       fold_32_bytes   \p, v0, v1
+       fold_32_bytes   \p, v2, v3
+       fold_32_bytes   \p, v4, v5
+       fold_32_bytes   \p, v6, v7
 
-       // check if there is another 64B in the buffer to be able to fold
-       b.lt            .L_fold_64_B_end_\@
+       subs            len, len, #128
+       b.lt            .Lfold_128_bytes_loop_done_\@
 
        if_will_cond_yield_neon
        stp             q0, q1, [sp, #.Lframe_local_offset]
@@ -353,217 +329,207 @@ CPU_LE( ext             v7.16b, v7.16b, v7.16b, #8      )
        ldp             q2, q3, [sp, #.Lframe_local_offset + 32]
        ldp             q4, q5, [sp, #.Lframe_local_offset + 64]
        ldp             q6, q7, [sp, #.Lframe_local_offset + 96]
-       ldr_l           q10, rk3, x8
-       movi            vzr.16b, #0             // init zero register
+       ld1             {fold_consts.2d}, [fold_consts_ptr]
        __pmull_init_\p
-       __pmull_pre_\p  v10
+       __pmull_pre_\p  fold_consts
        endif_yield_neon
 
-       b               .L_fold_64_B_loop_\@
-
-.L_fold_64_B_end_\@:
-       // at this point, the buffer pointer is pointing at the last y Bytes
-       // of the buffer the 64B of folded data is in 4 of the vector
-       // registers: v0, v1, v2, v3
-
-       // fold the 8 vector registers to 1 vector register with different
-       // constants
-
-       ldr_l           q10, rk9, x8
-       __pmull_pre_\p  v10
-
-       fold16          \p, v0, rk11
-       fold16          \p, v1, rk13
-       fold16          \p, v2, rk15
-       fold16          \p, v3, rk17
-       fold16          \p, v4, rk19
-       fold16          \p, v5, rk1
-       fold16          \p, v6
-
-       // instead of 64, we add 48 to the loop counter to save 1 instruction
-       // from the loop instead of a cmp instruction, we use the negative
-       // flag with the jl instruction
-       adds            arg3, arg3, #(128-16)
-       b.lt            .L_final_reduction_for_128_\@
-
-       // now we have 16+y bytes left to reduce. 16 Bytes is in register v7
-       // and the rest is in memory. We can fold 16 bytes at a time if y>=16
-       // continue folding 16B at a time
-
-.L_16B_reduction_loop_\@:
-       __pmull_\p      v8, v7, v10
-       __pmull_\p      v7, v7, v10, 2
+       b               .Lfold_128_bytes_loop_\@
+
+.Lfold_128_bytes_loop_done_\@:
+
+       // Now fold the 112 bytes in v0-v6 into the 16 bytes in v7.
+
+       // Fold across 64 bytes.
+       add             fold_consts_ptr, fold_consts_ptr, #16
+       ld1             {fold_consts.2d}, [fold_consts_ptr], #16
+       __pmull_pre_\p  fold_consts
+       fold_16_bytes   \p, v0, v4
+       fold_16_bytes   \p, v1, v5
+       fold_16_bytes   \p, v2, v6
+       fold_16_bytes   \p, v3, v7, 1
+       // Fold across 32 bytes.
+       fold_16_bytes   \p, v4, v6
+       fold_16_bytes   \p, v5, v7, 1
+       // Fold across 16 bytes.
+       fold_16_bytes   \p, v6, v7
+
+       // Add 128 to get the correct number of data bytes remaining in 0...127
+       // (not counting v7), following the previous extra subtraction by 128.
+       // Then subtract 16 to simplify the termination condition of the
+       // following loop.
+       adds            len, len, #(128-16)
+
+       // While >= 16 data bytes remain (not counting v7), fold the 16 bytes v7
+       // into them, storing the result back into v7.
+       b.lt            .Lfold_16_bytes_loop_done_\@
+.Lfold_16_bytes_loop_\@:
+       __pmull_\p      v8, v7, fold_consts
+       __pmull_\p      v7, v7, fold_consts, 2
        eor             v7.16b, v7.16b, v8.16b
-
-       ldr             q0, [arg2], #16
+       ldr             q0, [buf], #16
 CPU_LE(        rev64           v0.16b, v0.16b                  )
 CPU_LE(        ext             v0.16b, v0.16b, v0.16b, #8      )
        eor             v7.16b, v7.16b, v0.16b
-       subs            arg3, arg3, #16
-
-       // instead of a cmp instruction, we utilize the flags with the
-       // jge instruction equivalent of: cmp arg3, 16-16
-       // check if there is any more 16B in the buffer to be able to fold
-       b.ge            .L_16B_reduction_loop_\@
-
-       // now we have 16+z bytes left to reduce, where 0<= z < 16.
-       // first, we reduce the data in the xmm7 register
-
-.L_final_reduction_for_128_\@:
-       // check if any more data to fold. If not, compute the CRC of
-       // the final 128 bits
-       adds            arg3, arg3, #16
-       b.eq            .L_128_done_\@
-
-       // here we are getting data that is less than 16 bytes.
-       // since we know that there was data before the pointer, we can
-       // offset the input pointer before the actual point, to receive
-       // exactly 16 bytes. after that the registers need to be adjusted.
-.L_get_last_two_regs_\@:
-       add             arg2, arg2, arg3
-       ldr             q1, [arg2, #-16]
-CPU_LE(        rev64           v1.16b, v1.16b                  )
-CPU_LE(        ext             v1.16b, v1.16b, v1.16b, #8      )
-
-       // get rid of the extra data that was loaded before
-       // load the shift constant
-       adr_l           x4, tbl_shf_table + 16
-       sub             x4, x4, arg3
-       ld1             {v0.16b}, [x4]
-
-       // shift v2 to the left by arg3 bytes
-       tbl             v2.16b, {v7.16b}, v0.16b
-
-       // shift v7 to the right by 16-arg3 bytes
-       movi            v9.16b, #0x80
-       eor             v0.16b, v0.16b, v9.16b
-       tbl             v7.16b, {v7.16b}, v0.16b
-
-       // blend
-       sshr            v0.16b, v0.16b, #7      // convert to 8-bit mask
-       bsl             v0.16b, v2.16b, v1.16b
-
-       // fold 16 Bytes
-       __pmull_\p      v8, v7, v10
-       __pmull_\p      v7, v7, v10, 2
-       eor             v7.16b, v7.16b, v8.16b
-       eor             v7.16b, v7.16b, v0.16b
+       subs            len, len, #16
+       b.ge            .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 v7), following the previous extra subtraction by 16.
+       adds            len, len, #16
+       b.eq            .Lreduce_final_16_bytes_\@
+
+.Lhandle_partial_segment_\@:
+       // Reduce the last '16 + len' bytes where 1 <= len <= 15 and the first
+       // 16 bytes are in v7 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.
+
+       // v0 = last 16 original data bytes
+       add             buf, buf, len
+       ldr             q0, [buf, #-16]
+CPU_LE(        rev64           v0.16b, v0.16b                  )
+CPU_LE(        ext             v0.16b, v0.16b, v0.16b, #8      )
 
-.L_128_done_\@:
-       // compute crc of a 128-bit value
-       ldr_l           q10, rk5, x8            // rk5 and rk6 in xmm10
-       __pmull_pre_\p  v10
+       // v1 = high order part of second chunk: v7 left-shifted by 'len' bytes.
+       adr_l           x4, .Lbyteshift_table + 16
+       sub             x4, x4, len
+       ld1             {v2.16b}, [x4]
+       tbl             v1.16b, {v7.16b}, v2.16b
 
-       // 64b fold
-       ext             v0.16b, vzr.16b, v7.16b, #8
-       mov             v7.d[0], v7.d[1]
-       __pmull_\p      v7, v7, v10
-       eor             v7.16b, v7.16b, v0.16b
+       // v3 = first chunk: v7 right-shifted by '16-len' bytes.
+       movi            v3.16b, #0x80
+       eor             v2.16b, v2.16b, v3.16b
+       tbl             v3.16b, {v7.16b}, v2.16b
 
-       // 32b fold
-       ext             v0.16b, v7.16b, vzr.16b, #4
-       mov             v7.s[3], vzr.s[0]
-       __pmull_\p      v0, v0, v10, 2
-       eor             v7.16b, v7.16b, v0.16b
+       // Convert to 8-bit masks: 'len' 0x00 bytes, then '16-len' 0xff bytes.
+       sshr            v2.16b, v2.16b, #7
 
-       // barrett reduction
-       ldr_l           q10, rk7, x8
-       __pmull_pre_\p  v10
-       mov             v0.d[0], v7.d[1]
+       // v2 = second chunk: 'len' bytes from v0 (low-order bytes),
+       // then '16-len' bytes from v1 (high-order bytes).
+       bsl             v2.16b, v1.16b, v0.16b
 
-       __pmull_\p      v0, v0, v10
-       ext             v0.16b, vzr.16b, v0.16b, #12
-       __pmull_\p      v0, v0, v10, 2
-       ext             v0.16b, vzr.16b, v0.16b, #12
+       // Fold the first chunk into the second chunk, storing the result in v7.
+       __pmull_\p      v0, v3, fold_consts
+       __pmull_\p      v7, v3, fold_consts, 2
        eor             v7.16b, v7.16b, v0.16b
-       mov             w0, v7.s[1]
-
-.L_cleanup_\@:
-       // scale the result back to 16 bits
-       lsr             x0, x0, #16
+       eor             v7.16b, v7.16b, v2.16b
+
+.Lreduce_final_16_bytes_\@:
+       // Reduce the 128-bit value M(x), stored in v7, to the final 16-bit CRC.
+
+       movi            v2.16b, #0              // init zero register
+
+       // Load 'x^48 * (x^48 mod G(x))' and 'x^48 * (x^80 mod G(x))'.
+       ld1             {fold_consts.2d}, [fold_consts_ptr], #16
+       __pmull_pre_\p  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.
+       ext             v0.16b, v2.16b, v7.16b, #8
+       __pmull_\p      v7, v7, fold_consts, 2  // high bits * x^48 * (x^80 mod G(x))
+       eor             v0.16b, v0.16b, v7.16b  // + 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.
+       ext             v1.16b, v0.16b, v2.16b, #12     // extract high 32 bits
+       mov             v0.s[3], v2.s[0]        // zero high 32 bits
+       __pmull_\p      v1, v1, fold_consts     // high 32 bits * x^48 * (x^48 mod G(x))
+       eor             v0.16b, v0.16b, v1.16b  // + low bits
+
+       // Load G(x) and floor(x^48 / G(x)).
+       ld1             {fold_consts.2d}, [fold_consts_ptr]
+       __pmull_pre_\p  fold_consts
+
+       // Use Barrett reduction to compute the final CRC value.
+       __pmull_\p      v1, v0, fold_consts, 2  // high 32 bits * floor(x^48 / G(x))
+       ushr            v1.2d, v1.2d, #32       // /= x^32
+       __pmull_\p      v1, v1, fold_consts     // *= G(x)
+       ushr            v0.2d, v0.2d, #48
+       eor             v0.16b, v0.16b, v1.16b  // + low 16 nonzero bits
+       // Final CRC value (x^16 * M(x)) mod G(x) is in low 16 bits of v0.
+
+       umov            w0, v0.h[0]
        frame_pop
        ret
 
-.L_less_than_128_\@:
-       cbz             arg3, .L_cleanup_\@
+.Lless_than_256_bytes_\@:
+       // Checksumming a buffer of length 16...255 bytes
 
-       movi            v0.16b, #0
-       mov             v0.s[3], arg1_low32     // get the initial crc value
+       adr_l           fold_consts_ptr, .Lfold_across_16_bytes_consts
 
-       ldr             q7, [arg2], #0x10
+       // Load the first 16 data bytes.
+       ldr             q7, [buf], #0x10
 CPU_LE(        rev64           v7.16b, v7.16b                  )
 CPU_LE(        ext             v7.16b, v7.16b, v7.16b, #8      )
-       eor             v7.16b, v7.16b, v0.16b  // xor the initial crc value
-
-       cmp             arg3, #16
-       b.eq            .L_128_done_\@          // exactly 16 left
 
-       ldr_l           q10, rk1, x8            // rk1 and rk2 in xmm10
-       __pmull_pre_\p  v10
+       // XOR the first 16 data *bits* with the initial CRC value.
+       movi            v0.16b, #0
+       mov             v0.h[7], init_crc
+       eor             v7.16b, v7.16b, v0.16b
 
-       // update the counter. subtract 32 instead of 16 to save one
-       // instruction from the loop
-       subs            arg3, arg3, #32
-       b.ge            .L_16B_reduction_loop_\@
+       // Load the fold-across-16-bytes constants.
+       ld1             {fold_consts.2d}, [fold_consts_ptr], #16
+       __pmull_pre_\p  fold_consts
 
-       add             arg3, arg3, #16
-       b               .L_get_last_two_regs_\@
+       cmp             len, #16
+       b.eq            .Lreduce_final_16_bytes_\@      // len == 16
+       subs            len, len, #32
+       b.ge            .Lfold_16_bytes_loop_\@         // 32 <= len <= 255
+       add             len, len, #16
+       b               .Lhandle_partial_segment_\@     // 17 <= len <= 31
        .endm
 
+//
+// u16 crc_t10dif_pmull_p8(u16 init_crc, const u8 *buf, size_t len);
+//
+// Assumes len >= 16.
+//
 ENTRY(crc_t10dif_pmull_p8)
        crc_t10dif_pmull        p8
 ENDPROC(crc_t10dif_pmull_p8)
 
        .align          5
+//
+// u16 crc_t10dif_pmull_p64(u16 init_crc, const u8 *buf, size_t len);
+//
+// Assumes len >= 16.
+//
 ENTRY(crc_t10dif_pmull_p64)
        crc_t10dif_pmull        p64
 ENDPROC(crc_t10dif_pmull_p64)
 
-// precomputed constants
-// these constants are precomputed from the poly:
-// 0x8bb70000 (0x8bb7 scaled to 32 bits)
        .section        ".rodata", "a"
        .align          4
-// Q = 0x18BB70000
-// rk1 = 2^(32*3) mod Q << 32
-// rk2 = 2^(32*5) mod Q << 32
-// rk3 = 2^(32*15) mod Q << 32
-// rk4 = 2^(32*17) mod Q << 32
-// rk5 = 2^(32*3) mod Q << 32
-// rk6 = 2^(32*2) mod Q << 32
-// rk7 = floor(2^64/Q)
-// rk8 = Q
-
-rk1:   .octa           0x06df0000000000002d56000000000000
-rk3:   .octa           0x7cf50000000000009d9d000000000000
-rk5:   .octa           0x13680000000000002d56000000000000
-rk7:   .octa           0x000000018bb7000000000001f65a57f8
-rk9:   .octa           0xbfd6000000000000ceae000000000000
-rk11:  .octa           0x713c0000000000001e16000000000000
-rk13:  .octa           0x80a6000000000000f7f9000000000000
-rk15:  .octa           0xe658000000000000044c000000000000
-rk17:  .octa           0xa497000000000000ad18000000000000
-rk19:  .octa           0xe7b50000000000006ee3000000000000
-
-tbl_shf_table:
-// use these values for shift constants for the tbl/tbx instruction
-// different alignments result in values as shown:
-//     DDQ 0x008f8e8d8c8b8a898887868584838281 # shl 15 (16-1) / shr1
-//     DDQ 0x01008f8e8d8c8b8a8988878685848382 # shl 14 (16-3) / shr2
-//     DDQ 0x0201008f8e8d8c8b8a89888786858483 # shl 13 (16-4) / shr3
-//     DDQ 0x030201008f8e8d8c8b8a898887868584 # shl 12 (16-4) / shr4
-//     DDQ 0x04030201008f8e8d8c8b8a8988878685 # shl 11 (16-5) / shr5
-//     DDQ 0x0504030201008f8e8d8c8b8a89888786 # shl 10 (16-6) / shr6
-//     DDQ 0x060504030201008f8e8d8c8b8a898887 # shl 9  (16-7) / shr7
-//     DDQ 0x07060504030201008f8e8d8c8b8a8988 # shl 8  (16-8) / shr8
-//     DDQ 0x0807060504030201008f8e8d8c8b8a89 # shl 7  (16-9) / shr9
-//     DDQ 0x090807060504030201008f8e8d8c8b8a # shl 6  (16-10) / shr10
-//     DDQ 0x0a090807060504030201008f8e8d8c8b # shl 5  (16-11) / shr11
-//     DDQ 0x0b0a090807060504030201008f8e8d8c # shl 4  (16-12) / shr12
-//     DDQ 0x0c0b0a090807060504030201008f8e8d # shl 3  (16-13) / shr13
-//     DDQ 0x0d0c0b0a090807060504030201008f8e # shl 2  (16-14) / shr14
-//     DDQ 0x0e0d0c0b0a090807060504030201008f # shl 1  (16-15) / shr15
 
+// 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))
+
+// 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
index 242757cc6da919dee302e85dc85eb4ad7839dd08..dd325829ee44f92d30c435392f2bcada92f29825 100644 (file)
@@ -22,8 +22,8 @@
 
 #define CRC_T10DIF_PMULL_CHUNK_SIZE    16U
 
-asmlinkage u16 crc_t10dif_pmull_p64(u16 init_crc, const u8 buf[], u64 len);
-asmlinkage u16 crc_t10dif_pmull_p8(u16 init_crc, const u8 buf[], u64 len);
+asmlinkage u16 crc_t10dif_pmull_p8(u16 init_crc, const u8 *buf, size_t len);
+asmlinkage u16 crc_t10dif_pmull_p64(u16 init_crc, const u8 *buf, size_t len);
 
 static int crct10dif_init(struct shash_desc *desc)
 {