/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Core of the accelerated CRC algorithm.
* In your file, define the constants and CRC_FUNCTION_NAME
* Then include this file.
*
* Calculate the checksum of data that is 16 byte aligned and a multiple of
* 16 bytes.
*
* The first step is to reduce it to 1024 bits. We do this in 8 parallel
* chunks in order to mask the latency of the vpmsum instructions. If we
* have more than 32 kB of data to checksum we repeat this step multiple
* times, passing in the previous 1024 bits.
*
* The next step is to reduce the 1024 bits to 64 bits. This step adds
* 32 bits of 0s to the end - this matches what a CRC does. We just
* calculate constants that land the data in this 32 bits.
*
* We then use fixed point Barrett reduction to compute a mod n over GF(2)
* for n = CRC using POWER8 instructions. We use x = 32.
*
* http://en.wikipedia.org/wiki/Barrett_reduction
*
* Copyright (C) 2015 Anton Blanchard <anton@au.ibm.com>, IBM
*/
#include <asm/ppc_asm.h>
#include <asm/ppc-opcode.h>
#define MAX_SIZE 32768
.text
#if defined(__BIG_ENDIAN__) && defined(REFLECT)
#define BYTESWAP_DATA
#elif defined(__LITTLE_ENDIAN__) && !defined(REFLECT)
#define BYTESWAP_DATA
#else
#undef BYTESWAP_DATA
#endif
#define off16 r25
#define off32 r26
#define off48 r27
#define off64 r28
#define off80 r29
#define off96 r30
#define off112 r31
#define const1 v24
#define const2 v25
#define byteswap v26
#define mask_32bit v27
#define mask_64bit v28
#define zeroes v29
#ifdef BYTESWAP_DATA
#define VPERM(A, B, C, D) vperm A, B, C, D
#else
#define VPERM(A, B, C, D)
#endif
/* unsigned int CRC_FUNCTION_NAME(unsigned int crc, void *p, unsigned long len) */
FUNC_START(CRC_FUNCTION_NAME)
std r31,-8(r1)
std r30,-16(r1)
std r29,-24(r1)
std r28,-32(r1)
std r27,-40(r1)
std r26,-48(r1)
std r25,-56(r1)
li off16,16
li off32,32
li off48,48
li off64,64
li off80,80
li off96,96
li off112,112
li r0,0
/* Enough room for saving 10 non volatile VMX registers */
subi r6,r1,56+10*16
subi r7,r1,56+2*16
stvx v20,0,r6
stvx v21,off16,r6
stvx v22,off32,r6
stvx v23,off48,r6
stvx v24,off64,r6
stvx v25,off80,r6
stvx v26,off96,r6
stvx v27,off112,r6
stvx v28,0,r7
stvx v29,off16,r7
mr r10,r3
vxor zeroes,zeroes,zeroes
vspltisw v0,-1
vsldoi mask_32bit,zeroes,v0,4
vsldoi mask_64bit,zeroes,v0,8
/* Get the initial value into v8 */
vxor v8,v8,v8
MTVRD(v8, R3)
#ifdef REFLECT
vsldoi v8,zeroes,v8,8 /* shift into bottom 32 bits */
#else
vsldoi v8,v8,zeroes,4 /* shift into top 32 bits */
#endif
#ifdef BYTESWAP_DATA
addis r3,r2,.byteswap_constant@toc@ha
addi r3,r3,.byteswap_constant@toc@l
lvx byteswap,0,r3
addi r3,r3,16
#endif
cmpdi r5,256
blt .Lshort
rldicr r6,r5,0,56
/* Checksum in blocks of MAX_SIZE */
1: lis r7,MAX_SIZE@h
ori r7,r7,MAX_SIZE@l
mr r9,r7
cmpd r6,r7
bgt 2f
mr r7,r6
2: subf r6,r7,r6
/* our main loop does 128 bytes at a time */
srdi r7,r7,7
/*
* Work out the offset into the constants table to start at. Each
* constant is 16 bytes, and it is used against 128 bytes of input
* data - 128 / 16 = 8
*/
sldi r8,r7,4
srdi r9,r9,3
subf r8,r8,r9
/* We reduce our final 128 bytes in a separate step */
addi r7,r7,-1
mtctr r7
addis r3,r2,.constants@toc@ha
addi r3,r3,.constants@toc@l
/* Find the start of our constants */
add r3,r3,r8
/* zero v0-v7 which will contain our checksums */
vxor v0,v0,v0
vxor v1,v1,v1
vxor v2,v2,v2
vxor v3,v3,v3
vxor v4,v4,v4
vxor v5,v5,v5
vxor v6,v6,v6
vxor v7,v7,v7
lvx const1,0,r3
/*
* If we are looping back to consume more data we use the values
* already in v16-v23.
*/
cmpdi r0,1
beq 2f
/* First warm up pass */
lvx v16,0,r4
lvx v17,off16,r4
VPERM(v16,v16,v16,byteswap)
VPERM(v17,v17,v17,byteswap)
lvx v18,off32,r4
lvx v19,off48,r4
VPERM(v18,v18,v18,byteswap)
VPERM(v19,v19,v19,byteswap)
lvx v20,off64,r4
lvx v21,off80,r4
VPERM(v20,v20,v20,byteswap)
VPERM(v21,v21,v21,byteswap)
lvx v22,off96,r4
lvx v23,off112,r4
VPERM(v22,v22,v22,byteswap)
VPERM(v23,v23,v23,byteswap)
addi r4,r4,8*16
/* xor in initial value */
vxor v16,v16,v8
2: bdz .Lfirst_warm_up_done
addi r3,r3,16
lvx const2,0,r3
/* Second warm up pass */
VPMSUMD(v8,v16,const1)
lvx v16,0,r4
VPERM(v16,v16,v16,byteswap)
ori r2,r2,0
VPMSUMD(v9,v17,const1)
lvx v17,off16,r4
VPERM(v17,v17,v17,byteswap)
ori r2,r2,0
VPMSUMD(v10,v18,const1)
lvx v18,off32,r4
VPERM(v18,v18,v18,byteswap)
ori r2,r2,0
VPMSUMD(v11,v19,const1)
lvx v19,off48,r4
VPERM(v19,v19,v19,byteswap)
ori r2,r2,0
VPMSUMD(v12,v20,const1)
lvx v20,off64,r4
VPERM(v20,v20,v20,byteswap)
ori r2,r2,0
VPMSUMD(v13,v21,const1)
lvx v21,off80,r4
VPERM(v21,v21,v21,byteswap)
ori r2,r2,0
VPMSUMD(v14,v22,const1)
lvx v22,off96,r4
VPERM(v22,v22,v22,byteswap)
ori r2,r2,0
VPMSUMD(v15,v23,const1)
lvx v23,off112,r4
VPERM(v23,v23,v23,byteswap)
addi r4,r4,8*16
bdz .Lfirst_cool_down
/*
* main loop. We modulo schedule it such that it takes three iterations
* to complete - first iteration load, second iteration vpmsum, third
* iteration xor.
*/
.balign 16
4: lvx const1,0,r3
addi r3,r3,16
ori r2,r2,0
vxor v0,v0,v8
VPMSUMD(v8,v16,const2)
lvx v16,0,r4
VPERM(v16,v16,v16,byteswap)
ori r2,r2,0
vxor v1,v1,v9
VPMSUMD(v9,v17,const2)
lvx v17,off16,r4
VPERM(v17,v17,v17,byteswap)
ori r2,r2,0
vxor v2,v2,v10
VPMSUMD(v10,v18,const2)
lvx v18,off32,r4
VPERM(v18,v18,v18,byteswap)
ori r2,r2,0
vxor v3,v3,v11
VPMSUMD(v11,v19,const2)
lvx v19,off48,r4
VPERM(v19,v19,v19,byteswap)
lvx const2,0,r3
ori r2,r2,0
vxor v4,v4,v12
VPMSUMD(v12,v20,const1)
lvx v20,off64,r4
VPERM(v20,v20,v20,byteswap)
ori r2,r2,0
vxor v5,v5,v13
VPMSUMD(v13,v21,const1)
lvx v21,off80,r4
VPERM(v21,v21,v21,byteswap)
ori r2,r2,0
vxor v6,v6,v14
VPMSUMD(v14,v22,const1)
lvx v22,off96,r4
VPERM(v22,v22,v22,byteswap)
ori r2,r2,0
vxor v7,v7,v15
VPMSUMD(v15,v23,const1)
lvx v23,off112,r4
VPERM(v23,v23,v23,byteswap)
addi r4,r4,8*16
bdnz 4b
.Lfirst_cool_down:
/* First cool down pass */
lvx const1,0,r3
addi r3,r3,16
vxor v0,v0,v8
VPMSUMD(v8,v16,const1)
ori r2,r2,0
vxor v1,v1,v9
VPMSUMD(v9,v17,const1)
ori r2,r2,0
vxor v2,v2,v10
VPMSUMD(v10,v18,const1)
ori r2,r2,0
vxor v3,v3,v11
VPMSUMD(v11,v19,const1)
ori r2,r2,0
vxor v4,v4,v12
VPMSUMD(v12,v20,const1)
ori r2,r2,0
vxor v5,v5,v13
VPMSUMD(v13,v21,const1)
ori r2,r2,0
vxor v6,v6,v14
VPMSUMD(v14,v22,const1)
ori r2,r2,0
vxor v7,v7,v15
VPMSUMD(v15,v23,const1)
ori r2,r2,0
.Lsecond_cool_down:
/* Second cool down pass */
vxor v0,v0,v8
vxor v1,v1,v9
vxor v2,v2,v10
vxor v3,v3,v11
vxor v4,v4,v12
vxor v5,v5,v13
vxor v6,v6,v14
vxor v7,v7,v15
#ifdef REFLECT
/*
* vpmsumd produces a 96 bit result in the least significant bits
* of the register. Since we are bit reflected we have to shift it
* left 32 bits so it occupies the least significant bits in the
* bit reflected domain.
*/
vsldoi v0,v0,zeroes,4
vsldoi v1,v1,zeroes,4
vsldoi v2,v2,zeroes,4
vsldoi v3,v3,zeroes,4
vsldoi v4,v4,zeroes,4
vsldoi v5,v5,zeroes,4
vsldoi v6,v6,zeroes,4
vsldoi v7,v7,zeroes,4
#endif
/* xor with last 1024 bits */
lvx v8,0,r4
lvx v9,off16,r4
VPERM(v8,v8,v8,byteswap)
VPERM(v9,v9,v9,byteswap)
lvx v10,off32,r4
lvx v11,off48,r4
VPERM(v10,v10,v10,byteswap)
VPERM(v11,v11,v11,byteswap)
lvx v12,off64,r4
lvx v13,off80,r4
VPERM(v12,v12,v12,byteswap)
VPERM(v13,v13,v13,byteswap)
lvx v14,off96,r4
lvx v15,off112,r4
VPERM(v14,v14,v14,byteswap)
VPERM(v15,v15,v15,byteswap)
addi r4,r4,8*16
vxor v16,v0,v8
vxor v17,v1,v9
vxor v18,v2,v10
vxor v19,v3,v11
vxor v20,v4,v12
vxor v21,v5,v13
vxor v22,v6,v14
vxor v23,v7,v15
li r0,1
cmpdi r6,0
addi r6,r6,128
bne 1b
/* Work out how many bytes we have left */
andi. r5,r5,127
/* Calculate where in the constant table we need to start */
subfic r6,r5,128
add r3,r3,r6
/* How many 16 byte chunks are in the tail */
srdi r7,r5,4
mtctr r7
/*
* Reduce the previously calculated 1024 bits to 64 bits, shifting
* 32 bits to include the trailing 32 bits of zeros
*/
lvx v0,0,r3
lvx v1,off16,r3
lvx v2,off32,r3
lvx v3,off48,r3
lvx v4,off64,r3
lvx v5,off80,r3
lvx v6,off96,r3
lvx v7,off112,r3
addi r3,r3,8*16
VPMSUMW(v0,v16,v0)
VPMSUMW(v1,v17,v1)
VPMSUMW(v2,v18,v2)
VPMSUMW(v3,v19,v3)
VPMSUMW(v4,v20,v4)
VPMSUMW(v5,v21,v5)
VPMSUMW(v6,v22,v6)
VPMSUMW(v7,v23,v7)
/* Now reduce the tail (0 - 112 bytes) */
cmpdi r7,0
beq 1f
lvx v16,0,r4
lvx v17,0,r3
VPERM(v16,v16,v16,byteswap)
VPMSUMW(v16,v16,v17)
vxor v0,v0,v16
bdz 1f
lvx v16,off16,r4
lvx v17,off16,r3
VPERM(v16,v16,v16,byteswap)
VPMSUMW(v16,v16,v17)
vxor v0,v0,v16
bdz 1f
lvx v16,off32,r4
lvx v17,off32,r3
VPERM(v16,v16,v16,byteswap)
VPMSUMW(v16,v16,v17)
vxor v0,v0,v16
bdz 1f
lvx v16,off48,r4
lvx v17,off48,r3
VPERM(v16,v16,v16,byteswap)
VPMSUMW(v16,v16,v17)
vxor v0,v0,v16
bdz 1f
lvx v16,off64,r4
lvx v17,off64,r3
VPERM(v16,v16,v16,byteswap)
VPMSUMW(v16,v16,v17)
vxor v0,v0,v16
bdz 1f
lvx v16,off80,r4
lvx v17,off80,r3
VPERM(v16,v16,v16,byteswap)
VPMSUMW(v16,v16,v17)
vxor v0,v0,v16
bdz 1f
lvx v16,off96,r4
lvx v17,off96,r3
VPERM(v16,v16,v16,byteswap)
VPMSUMW(v16,v16,v17)
vxor v0,v0,v16
/* Now xor all the parallel chunks together */
1: vxor v0,v0,v1
vxor v2,v2,v3
vxor v4,v4,v5
vxor v6,v6,v7
vxor v0,v0,v2
vxor v4,v4,v6
vxor v0,v0,v4
.Lbarrett_reduction:
/* Barrett constants */
addis r3,r2,.barrett_constants@toc@ha
addi r3,r3,.barrett_constants@toc@l
lvx const1,0,r3
lvx const2,off16,r3
vsldoi v1,v0,v0,8
vxor v0,v0,v1 /* xor two 64 bit results together */
#ifdef REFLECT
/* shift left one bit */
vspltisb v1,1
vsl v0,v0,v1
#endif
vand v0,v0,mask_64bit
#ifndef REFLECT
/*
* Now for the Barrett reduction algorithm. The idea is to calculate q,
* the multiple of our polynomial that we need to subtract. By
* doing the computation 2x bits higher (ie 64 bits) and shifting the
* result back down 2x bits, we round down to the nearest multiple.
*/
VPMSUMD(v1,v0,const1) /* ma */
vsldoi v1,zeroes,v1,8 /* q = floor(ma/(2^64)) */
VPMSUMD(v1,v1,const2) /* qn */
vxor v0,v0,v1 /* a - qn, subtraction is xor in GF(2) */
/*
* Get the result into r3. We need to shift it left 8 bytes:
* V0 [ 0 1 2 X ]
* V0 [ 0 X 2 3 ]
*/
vsldoi v0,v0,zeroes,8 /* shift result into top 64 bits */
#else
/*
* The reflected version of Barrett reduction. Instead of bit
* reflecting our data (which is expensive to do), we bit reflect our
* constants and our algorithm, which means the intermediate data in
* our vector registers goes from 0-63 instead of 63-0. We can reflect
* the algorithm because we don't carry in mod 2 arithmetic.
*/
vand v1,v0,mask_32bit /* bottom 32 bits of a */
VPMSUMD(v1,v1,const1) /* ma */
vand v1,v1,mask_32bit /* bottom 32bits of ma */
VPMSUMD(v1,v1,const2) /* qn */
vxor v0,v0,v1 /* a - qn, subtraction is xor in GF(2) */
/*
* Since we are bit reflected, the result (ie the low 32 bits) is in
* the high 32 bits. We just need to shift it left 4 bytes
* V0 [ 0 1 X 3 ]
* V0 [ 0 X 2 3 ]
*/
vsldoi v0,v0,zeroes,4 /* shift result into top 64 bits of */
#endif
/* Get it into r3 */
MFVRD(R3, v0)
.Lout:
subi r6,r1,56+10*16
subi r7,r1,56+2*16
lvx v20,0,r6
lvx v21,off16,r6
lvx v22,off32,r6
lvx v23,off48,r6
lvx v24,off64,r6
lvx v25,off80,r6
lvx v26,off96,r6
lvx v27,off112,r6
lvx v28,0,r7
lvx v29,off16,r7
ld r31,-8(r1)
ld r30,-16(r1)
ld r29,-24(r1)
ld r28,-32(r1)
ld r27,-40(r1)
ld r26,-48(r1)
ld r25,-56(r1)
blr
.Lfirst_warm_up_done:
lvx const1,0,r3
addi r3,r3,16
VPMSUMD(v8,v16,const1)
VPMSUMD(v9,v17,const1)
VPMSUMD(v10,v18,const1)
VPMSUMD(v11,v19,const1)
VPMSUMD(v12,v20,const1)
VPMSUMD(v13,v21,const1)
VPMSUMD(v14,v22,const1)
VPMSUMD(v15,v23,const1)
b .Lsecond_cool_down
.Lshort:
cmpdi r5,0
beq .Lzero
addis r3,r2,.short_constants@toc@ha
addi r3,r3,.short_constants@toc@l
/* Calculate where in the constant table we need to start */
subfic r6,r5,256
add r3,r3,r6
/* How many 16 byte chunks? */
srdi r7,r5,4
mtctr r7
vxor v19,v19,v19
vxor v20,v20,v20
lvx v0,0,r4
lvx v16,0,r3
VPERM(v0,v0,v16,byteswap)
vxor v0,v0,v8 /* xor in initial value */
VPMSUMW(v0,v0,v16)
bdz .Lv0
lvx v1,off16,r4
lvx v17,off16,r3
VPERM(v1,v1,v17,byteswap)
VPMSUMW(v1,v1,v17)
bdz .Lv1
lvx v2,off32,r4
lvx v16,off32,r3
VPERM(v2,v2,v16,byteswap)
VPMSUMW(v2,v2,v16)
bdz .Lv2
lvx v3,off48,r4
lvx v17,off48,r3
VPERM(v3,v3,v17,byteswap)
VPMSUMW(v3,v3,v17)
bdz .Lv3
lvx v4,off64,r4
lvx v16,off64,r3
VPERM(v4,v4,v16,byteswap)
VPMSUMW(v4,v4,v16)
bdz .Lv4
lvx v5,off80,r4
lvx v17,off80,r3
VPERM(v5,v5,v17,byteswap)
VPMSUMW(v5,v5,v17)
bdz .Lv5
lvx v6,off96,r4
lvx v16,off96,r3
VPERM(v6,v6,v16,byteswap)
VPMSUMW(v6,v6,v16)
bdz .Lv6
lvx v7,off112,r4
lvx v17,off112,r3
VPERM(v7,v7,v17,byteswap)
VPMSUMW(v7,v7,v17)
bdz .Lv7
addi r3,r3,128
addi r4,r4,128
lvx v8,0,r4
lvx v16,0,r3
VPERM(v8,v8,v16,byteswap)
VPMSUMW(v8,v8,v16)
bdz .Lv8
lvx v9,off16,r4
lvx v17,off16,r3
VPERM(v9,v9,v17,byteswap)
VPMSUMW(v9,v9,v17)
bdz .Lv9
lvx v10,off32,r4
lvx v16,off32,r3
VPERM(v10,v10,v16,byteswap)
VPMSUMW(v10,v10,v16)
bdz .Lv10
lvx v11,off48,r4
lvx v17,off48,r3
VPERM(v11,v11,v17,byteswap)
VPMSUMW(v11,v11,v17)
bdz .Lv11
lvx v12,off64,r4
lvx v16,off64,r3
VPERM(v12,v12,v16,byteswap)
VPMSUMW(v12,v12,v16)
bdz .Lv12
lvx v13,off80,r4
lvx v17,off80,r3
VPERM(v13,v13,v17,byteswap)
VPMSUMW(v13,v13,v17)
bdz .Lv13
lvx v14,off96,r4
lvx v16,off96,r3
VPERM(v14,v14,v16,byteswap)
VPMSUMW(v14,v14,v16)
bdz .Lv14
lvx v15,off112,r4
lvx v17,off112,r3
VPERM(v15,v15,v17,byteswap)
VPMSUMW(v15,v15,v17)
.Lv15: vxor v19,v19,v15
.Lv14: vxor v20,v20,v14
.Lv13: vxor v19,v19,v13
.Lv12: vxor v20,v20,v12
.Lv11: vxor v19,v19,v11
.Lv10: vxor v20,v20,v10
.Lv9: vxor v19,v19,v9
.Lv8: vxor v20,v20,v8
.Lv7: vxor v19,v19,v7
.Lv6: vxor v20,v20,v6
.Lv5: vxor v19,v19,v5
.Lv4: vxor v20,v20,v4
.Lv3: vxor v19,v19,v3
.Lv2: vxor v20,v20,v2
.Lv1: vxor v19,v19,v1
.Lv0: vxor v20,v20,v0
vxor v0,v19,v20
b .Lbarrett_reduction
.Lzero:
mr r3,r10
b .Lout
FUNC_END(CRC_FUNCTION_NAME)
