1/* 2 * Copyright 2017, Matt Brown, IBM Corp. 3 * 4 * This program is free software; you can redistribute it and/or 5 * modify it under the terms of the GNU General Public License 6 * as published by the Free Software Foundation; either version 7 * 2 of the License, or (at your option) any later version. 8 * 9 * vpermxor$#.c 10 * 11 * Based on H. Peter Anvin's paper - The mathematics of RAID-6 12 * 13 * $#-way unrolled portable integer math RAID-6 instruction set 14 * This file is postprocessed using unroll.awk 15 * 16 * vpermxor$#.c makes use of the vpermxor instruction to optimise the RAID6 Q 17 * syndrome calculations. 18 * This can be run on systems which have both Altivec and vpermxor instruction. 19 * 20 * This instruction was introduced in POWER8 - ISA v2.07. 21 */ 22 23#include <altivec.h> 24#include <asm/ppc-opcode.h> 25#include <asm/cputable.h> 26#include <asm/switch_to.h> 27#include "algos.h" 28 29typedef vector unsigned char unative_t; 30#define NSIZE sizeof(unative_t) 31 32static const vector unsigned char gf_low = {0x1e, 0x1c, 0x1a, 0x18, 0x16, 0x14, 33 0x12, 0x10, 0x0e, 0x0c, 0x0a, 0x08, 34 0x06, 0x04, 0x02,0x00}; 35static const vector unsigned char gf_high = {0xfd, 0xdd, 0xbd, 0x9d, 0x7d, 0x5d, 36 0x3d, 0x1d, 0xe0, 0xc0, 0xa0, 0x80, 37 0x60, 0x40, 0x20, 0x00}; 38 39static void noinline raid6_vpermxor$#_gen_syndrome_real(int disks, size_t bytes, 40 void **ptrs) 41{ 42 u8 **dptr = (u8 **)ptrs; 43 u8 *p, *q; 44 int d, z, z0; 45 unative_t wp$$, wq$$, wd$$; 46 47 z0 = disks - 3; /* Highest data disk */ 48 p = dptr[z0+1]; /* XOR parity */ 49 q = dptr[z0+2]; /* RS syndrome */ 50 51 for (d = 0; d < bytes; d += NSIZE*$#) { 52 wp$$ = wq$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE]; 53 54 for (z = z0-1; z>=0; z--) { 55 wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE]; 56 /* P syndrome */ 57 wp$$ = vec_xor(wp$$, wd$$); 58 59 /* Q syndrome */ 60 asm(VPERMXOR(%0,%1,%2,%3):"=v"(wq$$):"v"(gf_high), "v"(gf_low), "v"(wq$$)); 61 wq$$ = vec_xor(wq$$, wd$$); 62 } 63 *(unative_t *)&p[d+NSIZE*$$] = wp$$; 64 *(unative_t *)&q[d+NSIZE*$$] = wq$$; 65 } 66} 67 68static void raid6_vpermxor$#_gen_syndrome(int disks, size_t bytes, void **ptrs) 69{ 70 preempt_disable(); 71 enable_kernel_altivec(); 72 73 raid6_vpermxor$#_gen_syndrome_real(disks, bytes, ptrs); 74 75 disable_kernel_altivec(); 76 preempt_enable(); 77} 78 79int raid6_have_altivec_vpermxor(void); 80#if $# == 1 81int raid6_have_altivec_vpermxor(void) 82{ 83 /* Check if arch has both altivec and the vpermxor instructions */ 84 return (cpu_has_feature(CPU_FTR_ALTIVEC_COMP) && 85 cpu_has_feature(CPU_FTR_ARCH_207S)); 86} 87#endif 88 89const struct raid6_calls raid6_vpermxor$# = { 90 .gen_syndrome = raid6_vpermxor$#_gen_syndrome, 91 .valid = raid6_have_altivec_vpermxor, 92 .name = "vpermxor$#", 93}; 94