1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * RAID-6 data recovery in dual failure mode based on the XC instruction. 4 * 5 * Copyright IBM Corp. 2016 6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> 7 */ 8 9 #include <linux/mm.h> 10 #include <linux/raid/pq.h> 11 #include "algos.h" 12 13 static inline void xor_block(u8 *p1, u8 *p2) 14 { 15 typedef struct { u8 _[256]; } addrtype; 16 17 asm volatile( 18 " xc 0(256,%[p1]),0(%[p2])\n" 19 : "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2), 20 [p1] "a" (p1), [p2] "a" (p2) : "cc"); 21 } 22 23 /* Recover two failed data blocks. */ 24 static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila, 25 int failb, void **ptrs) 26 { 27 u8 *p, *q, *dp, *dq; 28 const u8 *pbmul; /* P multiplier table for B data */ 29 const u8 *qmul; /* Q multiplier table (for both) */ 30 int i; 31 32 p = (u8 *)ptrs[disks-2]; 33 q = (u8 *)ptrs[disks-1]; 34 35 /* Compute syndrome with zero for the missing data pages 36 Use the dead data pages as temporary storage for 37 delta p and delta q */ 38 dp = (u8 *)ptrs[faila]; 39 ptrs[faila] = page_address(ZERO_PAGE(0)); 40 ptrs[disks-2] = dp; 41 dq = (u8 *)ptrs[failb]; 42 ptrs[failb] = page_address(ZERO_PAGE(0)); 43 ptrs[disks-1] = dq; 44 45 raid6_gen_syndrome(disks, bytes, ptrs); 46 47 /* Restore pointer table */ 48 ptrs[faila] = dp; 49 ptrs[failb] = dq; 50 ptrs[disks-2] = p; 51 ptrs[disks-1] = q; 52 53 /* Now, pick the proper data tables */ 54 pbmul = raid6_gfmul[raid6_gfexi[failb-faila]]; 55 qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]]; 56 57 /* Now do it... */ 58 while (bytes) { 59 xor_block(dp, p); 60 xor_block(dq, q); 61 for (i = 0; i < 256; i++) 62 dq[i] = pbmul[dp[i]] ^ qmul[dq[i]]; 63 xor_block(dp, dq); 64 p += 256; 65 q += 256; 66 dp += 256; 67 dq += 256; 68 bytes -= 256; 69 } 70 } 71 72 /* Recover failure of one data block plus the P block */ 73 static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila, 74 void **ptrs) 75 { 76 u8 *p, *q, *dq; 77 const u8 *qmul; /* Q multiplier table */ 78 int i; 79 80 p = (u8 *)ptrs[disks-2]; 81 q = (u8 *)ptrs[disks-1]; 82 83 /* Compute syndrome with zero for the missing data page 84 Use the dead data page as temporary storage for delta q */ 85 dq = (u8 *)ptrs[faila]; 86 ptrs[faila] = page_address(ZERO_PAGE(0)); 87 ptrs[disks-1] = dq; 88 89 raid6_gen_syndrome(disks, bytes, ptrs); 90 91 /* Restore pointer table */ 92 ptrs[faila] = dq; 93 ptrs[disks-1] = q; 94 95 /* Now, pick the proper data tables */ 96 qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]]; 97 98 /* Now do it... */ 99 while (bytes) { 100 xor_block(dq, q); 101 for (i = 0; i < 256; i++) 102 dq[i] = qmul[dq[i]]; 103 xor_block(p, dq); 104 p += 256; 105 q += 256; 106 dq += 256; 107 bytes -= 256; 108 } 109 } 110 111 112 const struct raid6_recov_calls raid6_recov_s390xc = { 113 .data2 = raid6_2data_recov_s390xc, 114 .datap = raid6_datap_recov_s390xc, 115 .name = "s390xc", 116 }; 117