--- /dev/null
+//
+// Accelerated CRC-T10DIF using arm64 NEON and Crypto Extensions instructions
+//
+// Copyright (C) 2016 Linaro Ltd <ard.biesheuvel@linaro.org>
+//
+// 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.
+//
+
+//
+// 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.
+//
+// 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 w0
+ arg2 .req x1
+ arg3 .req x2
+
+ vzr .req v13
+
+ENTRY(crc_t10dif_pmull)
+ movi vzr.16b, #0 // init zero register
+
+ // 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 _less_than_128
+
+ // 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
+
+CPU_LE( rev64 v0.16b, v0.16b )
+CPU_LE( rev64 v1.16b, v1.16b )
+CPU_LE( rev64 v2.16b, v2.16b )
+CPU_LE( rev64 v3.16b, v3.16b )
+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 )
+CPU_LE( ext v3.16b, v3.16b, v3.16b, #8 )
+CPU_LE( ext v4.16b, v4.16b, v4.16b, #8 )
+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 q10, rk3 // xmm10 has rk3 and rk4
+ // type of pmull instruction
+ // will determine which constant to use
+
+ //
+ // 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
+
+
+ // fold 64B at a time. This section of the code folds 4 vector
+ // registers in parallel
+_fold_64_B_loop:
+
+ .macro fold64, reg1, reg2
+ ldp q11, q12, [arg2], #0x20
+
+ pmull2 v8.1q, \reg1\().2d, v10.2d
+ pmull \reg1\().1q, \reg1\().1d, v10.1d
+
+CPU_LE( rev64 v11.16b, v11.16b )
+CPU_LE( rev64 v12.16b, v12.16b )
+
+ pmull2 v9.1q, \reg2\().2d, v10.2d
+ pmull \reg2\().1q, \reg2\().1d, v10.1d
+
+CPU_LE( ext v11.16b, v11.16b, v11.16b, #8 )
+CPU_LE( ext v12.16b, v12.16b, v12.16b, #8 )
+
+ eor \reg1\().16b, \reg1\().16b, v8.16b
+ eor \reg2\().16b, \reg2\().16b, v9.16b
+ eor \reg1\().16b, \reg1\().16b, v11.16b
+ eor \reg2\().16b, \reg2\().16b, v12.16b
+ .endm
+
+ fold64 v0, v1
+ fold64 v2, v3
+ fold64 v4, v5
+ fold64 v6, v7
+
+ subs arg3, arg3, #128
+
+ // check if there is another 64B in the buffer to be able to fold
+ b.ge _fold_64_B_loop
+
+ // 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 q10, rk9
+
+ .macro fold16, reg, rk
+ pmull v8.1q, \reg\().1d, v10.1d
+ pmull2 \reg\().1q, \reg\().2d, v10.2d
+ .ifnb \rk
+ ldr q10, \rk
+ .endif
+ eor v7.16b, v7.16b, v8.16b
+ eor v7.16b, v7.16b, \reg\().16b
+ .endm
+
+ fold16 v0, rk11
+ fold16 v1, rk13
+ fold16 v2, rk15
+ fold16 v3, rk17
+ fold16 v4, rk19
+ fold16 v5, rk1
+ fold16 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 _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
+
+_16B_reduction_loop:
+ pmull v8.1q, v7.1d, v10.1d
+ pmull2 v7.1q, v7.2d, v10.2d
+ eor v7.16b, v7.16b, v8.16b
+
+ ldr q0, [arg2], #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 _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
+
+_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 _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.
+_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 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 v8.1q, v7.1d, v10.1d
+ pmull2 v7.1q, v7.2d, v10.2d
+ eor v7.16b, v7.16b, v8.16b
+ eor v7.16b, v7.16b, v0.16b
+
+_128_done:
+ // compute crc of a 128-bit value
+ ldr q10, rk5 // rk5 and rk6 in xmm10
+
+ // 64b fold
+ ext v0.16b, vzr.16b, v7.16b, #8
+ mov v7.d[0], v7.d[1]
+ pmull v7.1q, v7.1d, v10.1d
+ eor v7.16b, v7.16b, v0.16b
+
+ // 32b fold
+ ext v0.16b, v7.16b, vzr.16b, #4
+ mov v7.s[3], vzr.s[0]
+ pmull2 v0.1q, v0.2d, v10.2d
+ eor v7.16b, v7.16b, v0.16b
+
+ // barrett reduction
+_barrett:
+ ldr q10, rk7
+ mov v0.d[0], v7.d[1]
+
+ pmull v0.1q, v0.1d, v10.1d
+ ext v0.16b, vzr.16b, v0.16b, #12
+ pmull2 v0.1q, v0.2d, v10.2d
+ ext v0.16b, vzr.16b, v0.16b, #12
+ eor v7.16b, v7.16b, v0.16b
+ mov w0, v7.s[1]
+
+_cleanup:
+ // scale the result back to 16 bits
+ lsr x0, x0, #16
+ ret
+
+_less_than_128:
+ cbz arg3, _cleanup
+
+ movi v0.16b, #0
+ mov v0.s[3], arg1_low32 // get the initial crc value
+
+ ldr q7, [arg2], #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 _128_done // exactly 16 left
+ b.lt _less_than_16_left
+
+ ldr q10, rk1 // rk1 and rk2 in xmm10
+
+ // update the counter. subtract 32 instead of 16 to save one
+ // instruction from the loop
+ subs arg3, arg3, #32
+ b.ge _16B_reduction_loop
+
+ add arg3, arg3, #16
+ b _get_last_two_regs
+
+_less_than_16_left:
+ // shl r9, 4
+ adr x0, tbl_shf_table + 16
+ sub x0, x0, arg3
+ ld1 {v0.16b}, [x0]
+ movi v9.16b, #0x80
+ eor v0.16b, v0.16b, v9.16b
+ tbl v7.16b, {v7.16b}, v0.16b
+ b _128_done
+ENDPROC(crc_t10dif_pmull)
+
+// precomputed constants
+// these constants are precomputed from the poly:
+// 0x8bb70000 (0x8bb7 scaled to 32 bits)
+ .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
+
+ .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
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