//
// 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