########################################################################
# 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>
.text
#define arg1 %rdi
#define arg2 %rsi
#define arg3 %rdx
#define arg1_low32 %edi
ENTRY(crc_t10dif_pcl)
.align 16
# adjust the 16-bit initial_crc value, scale it to 32 bits
shl $16, arg1_low32
# Allocate Stack Space
mov %rsp, %rcx
sub $16*2, %rsp
# align stack to 16 byte boundary
and $~(0x10 - 1), %rsp
# check if smaller than 256
cmp $256, arg3
# for sizes less than 128, we can't fold 64B at a time...
jl _less_than_128
# load the initial crc value
movd arg1_low32, %xmm10 # initial crc
# 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.
pslldq $12, %xmm10
movdqa SHUF_MASK(%rip), %xmm11
# receive the initial 64B data, xor the initial crc value
movdqu 16*0(arg2), %xmm0
movdqu 16*1(arg2), %xmm1
movdqu 16*2(arg2), %xmm2
movdqu 16*3(arg2), %xmm3
movdqu 16*4(arg2), %xmm4
movdqu 16*5(arg2), %xmm5
movdqu 16*6(arg2), %xmm6
movdqu 16*7(arg2), %xmm7
pshufb %xmm11, %xmm0
# XOR the initial_crc value
pxor %xmm10, %xmm0
pshufb %xmm11, %xmm1
pshufb %xmm11, %xmm2
pshufb %xmm11, %xmm3
pshufb %xmm11, %xmm4
pshufb %xmm11, %xmm5
pshufb %xmm11, %xmm6
pshufb %xmm11, %xmm7
movdqa rk3(%rip), %xmm10 #xmm10 has rk3 and rk4
#imm value of pclmulqdq instruction
#will determine which constant to use
#################################################################
# we subtract 256 instead of 128 to save one instruction from the loop
sub $256, arg3
# 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 xmm
# registers in parallel
_fold_64_B_loop:
# update the buffer pointer
add $128, arg2 # buf += 64#
movdqu 16*0(arg2), %xmm9
movdqu 16*1(arg2), %xmm12
pshufb %xmm11, %xmm9
pshufb %xmm11, %xmm12
movdqa %xmm0, %xmm8
movdqa %xmm1, %xmm13
pclmulqdq $0x0 , %xmm10, %xmm0
pclmulqdq $0x11, %xmm10, %xmm8
pclmulqdq $0x0 , %xmm10, %xmm1
pclmulqdq $0x11, %xmm10, %xmm13
pxor %xmm9 , %xmm0
xorps %xmm8 , %xmm0
pxor %xmm12, %xmm1
xorps %xmm13, %xmm1
movdqu 16*2(arg2), %xmm9
movdqu 16*3(arg2), %xmm12
pshufb %xmm11, %xmm9
pshufb %xmm11, %xmm12
movdqa %xmm2, %xmm8
movdqa %xmm3, %xmm13
pclmulqdq $0x0, %xmm10, %xmm2
pclmulqdq $0x11, %xmm10, %xmm8
pclmulqdq $0x0, %xmm10, %xmm3
pclmulqdq $0x11, %xmm10, %xmm13
pxor %xmm9 , %xmm2
xorps %xmm8 , %xmm2
pxor %xmm12, %xmm3
xorps %xmm13, %xmm3
movdqu 16*4(arg2), %xmm9
movdqu 16*5(arg2), %xmm12
pshufb %xmm11, %xmm9
pshufb %xmm11, %xmm12
movdqa %xmm4, %xmm8
movdqa %xmm5, %xmm13
pclmulqdq $0x0, %xmm10, %xmm4
pclmulqdq $0x11, %xmm10, %xmm8
pclmulqdq $0x0, %xmm10, %xmm5
pclmulqdq $0x11, %xmm10, %xmm13
pxor %xmm9 , %xmm4
xorps %xmm8 , %xmm4
pxor %xmm12, %xmm5
xorps %xmm13, %xmm5
movdqu 16*6(arg2), %xmm9
movdqu 16*7(arg2), %xmm12
pshufb %xmm11, %xmm9
pshufb %xmm11, %xmm12
movdqa %xmm6 , %xmm8
movdqa %xmm7 , %xmm13
pclmulqdq $0x0 , %xmm10, %xmm6
pclmulqdq $0x11, %xmm10, %xmm8
pclmulqdq $0x0 , %xmm10, %xmm7
pclmulqdq $0x11, %xmm10, %xmm13
pxor %xmm9 , %xmm6
xorps %xmm8 , %xmm6
pxor %xmm12, %xmm7
xorps %xmm13, %xmm7
sub $128, arg3
# check if there is another 64B in the buffer to be able to fold
jge _fold_64_B_loop
##################################################################
add $128, arg2
# 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 xmm
# registers: xmm0, xmm1, xmm2, xmm3
# fold the 8 xmm registers to 1 xmm register with different constants
movdqa rk9(%rip), %xmm10
movdqa %xmm0, %xmm8
pclmulqdq $0x11, %xmm10, %xmm0
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
xorps %xmm0, %xmm7
movdqa rk11(%rip), %xmm10
movdqa %xmm1, %xmm8
pclmulqdq $0x11, %xmm10, %xmm1
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
xorps %xmm1, %xmm7
movdqa rk13(%rip), %xmm10
movdqa %xmm2, %xmm8
pclmulqdq $0x11, %xmm10, %xmm2
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
pxor %xmm2, %xmm7
movdqa rk15(%rip), %xmm10
movdqa %xmm3, %xmm8
pclmulqdq $0x11, %xmm10, %xmm3
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
xorps %xmm3, %xmm7
movdqa rk17(%rip), %xmm10
movdqa %xmm4, %xmm8
pclmulqdq $0x11, %xmm10, %xmm4
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
pxor %xmm4, %xmm7
movdqa rk19(%rip), %xmm10
movdqa %xmm5, %xmm8
pclmulqdq $0x11, %xmm10, %xmm5
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
xorps %xmm5, %xmm7
movdqa rk1(%rip), %xmm10 #xmm10 has rk1 and rk2
#imm value of pclmulqdq instruction
#will determine which constant to use
movdqa %xmm6, %xmm8
pclmulqdq $0x11, %xmm10, %xmm6
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
pxor %xmm6, %xmm7
# 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
add $128-16, arg3
jl _final_reduction_for_128
# now we have 16+y bytes left to reduce. 16 Bytes is in register xmm7
# 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:
movdqa %xmm7, %xmm8
pclmulqdq $0x11, %xmm10, %xmm7
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
movdqu (arg2), %xmm0
pshufb %xmm11, %xmm0
pxor %xmm0 , %xmm7
add $16, arg2
sub $16, arg3
# 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
jge _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
add $16, arg3
je _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_xmms:
movdqa %xmm7, %xmm2
movdqu -16(arg2, arg3), %xmm1
pshufb %xmm11, %xmm1
# get rid of the extra data that was loaded before
# load the shift constant
lea pshufb_shf_table+16(%rip), %rax
sub arg3, %rax
movdqu (%rax), %xmm0
# shift xmm2 to the left by arg3 bytes
pshufb %xmm0, %xmm2
# shift xmm7 to the right by 16-arg3 bytes
pxor mask1(%rip), %xmm0
pshufb %xmm0, %xmm7
pblendvb %xmm2, %xmm1 #xmm0 is implicit
# fold 16 Bytes
movdqa %xmm1, %xmm2
movdqa %xmm7, %xmm8
pclmulqdq $0x11, %xmm10, %xmm7
pclmulqdq $0x0 , %xmm10, %xmm8
pxor %xmm8, %xmm7
pxor %xmm2, %xmm7
_128_done:
# compute crc of a 128-bit value
movdqa rk5(%rip), %xmm10 # rk5 and rk6 in xmm10
movdqa %xmm7, %xmm0
#64b fold
pclmulqdq $0x1, %xmm10, %xmm7
pslldq $8 , %xmm0
pxor %xmm0, %xmm7
#32b fold
movdqa %xmm7, %xmm0
pand mask2(%rip), %xmm0
psrldq $12, %xmm7
pclmulqdq $0x10, %xmm10, %xmm7
pxor %xmm0, %xmm7
#barrett reduction
_barrett:
movdqa rk7(%rip), %xmm10 # rk7 and rk8 in xmm10
movdqa %xmm7, %xmm0
pclmulqdq $0x01, %xmm10, %xmm7
pslldq $4, %xmm7
pclmulqdq $0x11, %xmm10, %xmm7
pslldq $4, %xmm7
pxor %xmm0, %xmm7
pextrd $1, %xmm7, %eax
_cleanup:
# scale the result back to 16 bits
shr $16, %eax
mov %rcx, %rsp
ret
########################################################################
.align 16
_less_than_128:
# check if there is enough buffer to be able to fold 16B at a time
cmp $32, arg3
jl _less_than_32
movdqa SHUF_MASK(%rip), %xmm11
# now if there is, load the constants
movdqa rk1(%rip), %xmm10 # rk1 and rk2 in xmm10
movd arg1_low32, %xmm0 # get the initial crc value
pslldq $12, %xmm0 # align it to its correct place
movdqu (arg2), %xmm7 # load the plaintext
pshufb %xmm11, %xmm7 # byte-reflect the plaintext
pxor %xmm0, %xmm7
# update the buffer pointer
add $16, arg2
# update the counter. subtract 32 instead of 16 to save one
# instruction from the loop
sub $32, arg3
jmp _16B_reduction_loop
.align 16
_less_than_32:
# mov initial crc to the return value. this is necessary for
# zero-length buffers.
mov arg1_low32, %eax
test arg3, arg3
je _cleanup
movdqa SHUF_MASK(%rip), %xmm11
movd arg1_low32, %xmm0 # get the initial crc value
pslldq $12, %xmm0 # align it to its correct place
cmp $16, arg3
je _exact_16_left
jl _less_than_16_left
movdqu (arg2), %xmm7 # load the plaintext
pshufb %xmm11, %xmm7 # byte-reflect the plaintext
pxor %xmm0 , %xmm7 # xor the initial crc value
add $16, arg2
sub $16, arg3
movdqa rk1(%rip), %xmm10 # rk1 and rk2 in xmm10
jmp _get_last_two_xmms
.align 16
_less_than_16_left:
# use stack space to load data less than 16 bytes, zero-out
# the 16B in memory first.
pxor %xmm1, %xmm1
mov %rsp, %r11
movdqa %xmm1, (%r11)
cmp $4, arg3
jl _only_less_than_4
# backup the counter value
mov arg3, %r9
cmp $8, arg3
jl _less_than_8_left
# load 8 Bytes
mov (arg2), %rax
mov %rax, (%r11)
add $8, %r11
sub $8, arg3
add $8, arg2
_less_than_8_left:
cmp $4, arg3
jl _less_than_4_left
# load 4 Bytes
mov (arg2), %eax
mov %eax, (%r11)
add $4, %r11
sub $4, arg3
add $4, arg2
_less_than_4_left:
cmp $2, arg3
jl _less_than_2_left
# load 2 Bytes
mov (arg2), %ax
mov %ax, (%r11)
add $2, %r11
sub $2, arg3
add $2, arg2
_less_than_2_left:
cmp $1, arg3
jl _zero_left
# load 1 Byte
mov (arg2), %al
mov %al, (%r11)
_zero_left:
movdqa (%rsp), %xmm7
pshufb %xmm11, %xmm7
pxor %xmm0 , %xmm7 # xor the initial crc value
# shl r9, 4
lea pshufb_shf_table+16(%rip), %rax
sub %r9, %rax
movdqu (%rax), %xmm0
pxor mask1(%rip), %xmm0
pshufb %xmm0, %xmm7
jmp _128_done
.align 16
_exact_16_left:
movdqu (arg2), %xmm7
pshufb %xmm11, %xmm7
pxor %xmm0 , %xmm7 # xor the initial crc value
jmp _128_done
_only_less_than_4:
cmp $3, arg3
jl _only_less_than_3
# load 3 Bytes
mov (arg2), %al
mov %al, (%r11)
mov 1(arg2), %al
mov %al, 1(%r11)
mov 2(arg2), %al
mov %al, 2(%r11)
movdqa (%rsp), %xmm7
pshufb %xmm11, %xmm7
pxor %xmm0 , %xmm7 # xor the initial crc value
psrldq $5, %xmm7
jmp _barrett
_only_less_than_3:
cmp $2, arg3
jl _only_less_than_2
# load 2 Bytes
mov (arg2), %al
mov %al, (%r11)
mov 1(arg2), %al
mov %al, 1(%r11)
movdqa (%rsp), %xmm7
pshufb %xmm11, %xmm7
pxor %xmm0 , %xmm7 # xor the initial crc value
psrldq $6, %xmm7
jmp _barrett
_only_less_than_2:
# load 1 Byte
mov (arg2), %al
mov %al, (%r11)
movdqa (%rsp), %xmm7
pshufb %xmm11, %xmm7
pxor %xmm0 , %xmm7 # xor the initial crc value
psrldq $7, %xmm7
jmp _barrett
ENDPROC(crc_t10dif_pcl)
.data
# precomputed constants
# these constants are precomputed from the poly:
# 0x8bb70000 (0x8bb7 scaled to 32 bits)
.align 16
# 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:
.quad 0x2d56000000000000
rk2:
.quad 0x06df000000000000
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
mask1:
.octa 0x80808080808080808080808080808080
mask2:
.octa 0x00000000FFFFFFFFFFFFFFFFFFFFFFFF
SHUF_MASK:
.octa 0x000102030405060708090A0B0C0D0E0F
pshufb_shf_table:
# use these values for shift constants for the pshufb 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
.octa 0x8f8e8d8c8b8a89888786858483828100
.octa 0x000e0d0c0b0a09080706050403020100