//
// Accelerated CRC-T10DIF using ARM 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>
#ifdef CONFIG_CPU_ENDIAN_BE8
#define CPU_LE(code...)
#else
#define CPU_LE(code...) code
#endif
.text
.fpu crypto-neon-fp-armv8
arg1_low32 .req r0
arg2 .req r1
arg3 .req r2
qzr .req q13
q0l .req d0
q0h .req d1
q1l .req d2
q1h .req d3
q2l .req d4
q2h .req d5
q3l .req d6
q3h .req d7
q4l .req d8
q4h .req d9
q5l .req d10
q5h .req d11
q6l .req d12
q6h .req d13
q7l .req d14
q7h .req d15
ENTRY(crc_t10dif_pmull)
vmov.i8 qzr, #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...
blt _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.
vmov s0, arg1_low32 // initial crc
vext.8 q10, qzr, q0, #4
// receive the initial 64B data, xor the initial crc value
vld1.64 {q0-q1}, [arg2, :128]!
vld1.64 {q2-q3}, [arg2, :128]!
vld1.64 {q4-q5}, [arg2, :128]!
vld1.64 {q6-q7}, [arg2, :128]!
CPU_LE( vrev64.8 q0, q0 )
CPU_LE( vrev64.8 q1, q1 )
CPU_LE( vrev64.8 q2, q2 )
CPU_LE( vrev64.8 q3, q3 )
CPU_LE( vrev64.8 q4, q4 )
CPU_LE( vrev64.8 q5, q5 )
CPU_LE( vrev64.8 q6, q6 )
CPU_LE( vrev64.8 q7, q7 )
vswp d0, d1
vswp d2, d3
vswp d4, d5
vswp d6, d7
vswp d8, d9
vswp d10, d11
vswp d12, d13
vswp d14, d15
// XOR the initial_crc value
veor.8 q0, q0, q10
adr ip, rk3
vld1.64 {q10}, [ip, :128] // xmm10 has rk3 and rk4
//
// 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
vld1.64 {q11-q12}, [arg2, :128]!
vmull.p64 q8, \reg1\()h, d21
vmull.p64 \reg1, \reg1\()l, d20
vmull.p64 q9, \reg2\()h, d21
vmull.p64 \reg2, \reg2\()l, d20
CPU_LE( vrev64.8 q11, q11 )
CPU_LE( vrev64.8 q12, q12 )
vswp d22, d23
vswp d24, d25
veor.8 \reg1, \reg1, q8
veor.8 \reg2, \reg2, q9
veor.8 \reg1, \reg1, q11
veor.8 \reg2, \reg2, q12
.endm
fold64 q0, q1
fold64 q2, q3
fold64 q4, q5
fold64 q6, q7
subs arg3, arg3, #128
// check if there is another 64B in the buffer to be able to fold
bge _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
adr ip, rk9
vld1.64 {q10}, [ip, :128]!
.macro fold16, reg, rk
vmull.p64 q8, \reg\()l, d20
vmull.p64 \reg, \reg\()h, d21
.ifnb \rk
vld1.64 {q10}, [ip, :128]!
.endif
veor.8 q7, q7, q8
veor.8 q7, q7, \reg
.endm
fold16 q0, rk11
fold16 q1, rk13
fold16 q2, rk15
fold16 q3, rk17
fold16 q4, rk19
fold16 q5, rk1
fold16 q6
// 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)
blt _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:
vmull.p64 q8, d14, d20
vmull.p64 q7, d15, d21
veor.8 q7, q7, q8
vld1.64 {q0}, [arg2, :128]!
CPU_LE( vrev64.8 q0, q0 )
vswp d0, d1
veor.8 q7, q7, q0
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
bge _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
beq _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
sub arg2, arg2, #16
vld1.64 {q1}, [arg2]
CPU_LE( vrev64.8 q1, q1 )
vswp d2, d3
// get rid of the extra data that was loaded before
// load the shift constant
adr ip, tbl_shf_table + 16
sub ip, ip, arg3
vld1.8 {q0}, [ip]
// shift v2 to the left by arg3 bytes
vtbl.8 d4, {d14-d15}, d0
vtbl.8 d5, {d14-d15}, d1
// shift v7 to the right by 16-arg3 bytes
vmov.i8 q9, #0x80
veor.8 q0, q0, q9
vtbl.8 d18, {d14-d15}, d0
vtbl.8 d19, {d14-d15}, d1
// blend
vshr.s8 q0, q0, #7 // convert to 8-bit mask
vbsl.8 q0, q2, q1
// fold 16 Bytes
vmull.p64 q8, d18, d20
vmull.p64 q7, d19, d21
veor.8 q7, q7, q8
veor.8 q7, q7, q0
_128_done:
// compute crc of a 128-bit value
vldr d20, rk5
vldr d21, rk6 // rk5 and rk6 in xmm10
// 64b fold
vext.8 q0, qzr, q7, #8
vmull.p64 q7, d15, d20
veor.8 q7, q7, q0
// 32b fold
vext.8 q0, q7, qzr, #12
vmov s31, s3
vmull.p64 q0, d0, d21
veor.8 q7, q0, q7
// barrett reduction
_barrett:
vldr d20, rk7
vldr d21, rk8
vmull.p64 q0, d15, d20
vext.8 q0, qzr, q0, #12
vmull.p64 q0, d1, d21
vext.8 q0, qzr, q0, #12
veor.8 q7, q7, q0
vmov r0, s29
_cleanup:
// scale the result back to 16 bits
lsr r0, r0, #16
bx lr
_less_than_128:
teq arg3, #0
beq _cleanup
vmov.i8 q0, #0
vmov s3, arg1_low32 // get the initial crc value
vld1.64 {q7}, [arg2, :128]!
CPU_LE( vrev64.8 q7, q7 )
vswp d14, d15
veor.8 q7, q7, q0
cmp arg3, #16
beq _128_done // exactly 16 left
blt _less_than_16_left
// now if there is, load the constants
vldr d20, rk1
vldr d21, rk2 // rk1 and rk2 in xmm10
// check if there is enough buffer to be able to fold 16B at a time
subs arg3, arg3, #32
addlt arg3, arg3, #16
blt _get_last_two_regs
b _16B_reduction_loop
_less_than_16_left:
// shl r9, 4
adr ip, tbl_shf_table + 16
sub ip, ip, arg3
vld1.8 {q0}, [ip]
vmov.i8 q9, #0x80
veor.8 q0, q0, q9
vtbl.8 d18, {d14-d15}, d0
vtbl.8 d15, {d14-d15}, d1
vmov d14, d18
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
rk3: .quad 0x9d9d000000000000
rk4: .quad 0x7cf5000000000000
rk5: .quad 0x2d56000000000000
rk6: .quad 0x1368000000000000
rk7: .quad 0x00000001f65a57f8
rk8: .quad 0x000000018bb70000
rk9: .quad 0xceae000000000000
rk10: .quad 0xbfd6000000000000
rk11: .quad 0x1e16000000000000
rk12: .quad 0x713c000000000000
rk13: .quad 0xf7f9000000000000
rk14: .quad 0x80a6000000000000
rk15: .quad 0x044c000000000000
rk16: .quad 0xe658000000000000
rk17: .quad 0xad18000000000000
rk18: .quad 0xa497000000000000
rk19: .quad 0x6ee3000000000000
rk20: .quad 0xe7b5000000000000
rk1: .quad 0x2d56000000000000
rk2: .quad 0x06df000000000000
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
