| Martin Schwidefsky | f5b55fa | 2016-08-31 09:27:35 +0200 | [diff] [blame] | 1 | /* |
| 2 | * RAID-6 data recovery in dual failure mode based on the XC instruction. |
| 3 | * |
| 4 | * Copyright IBM Corp. 2016 |
| 5 | * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> |
| 6 | */ |
| 7 | |
| 8 | #include <linux/export.h> |
| 9 | #include <linux/raid/pq.h> |
| 10 | |
| 11 | static inline void xor_block(u8 *p1, u8 *p2) |
| 12 | { |
| 13 | typedef struct { u8 _[256]; } addrtype; |
| 14 | |
| 15 | asm volatile( |
| 16 | " xc 0(256,%[p1]),0(%[p2])\n" |
| 17 | : "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2), |
| 18 | [p1] "a" (p1), [p2] "a" (p2) : "cc"); |
| 19 | } |
| 20 | |
| 21 | /* Recover two failed data blocks. */ |
| 22 | static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila, |
| 23 | int failb, void **ptrs) |
| 24 | { |
| 25 | u8 *p, *q, *dp, *dq; |
| 26 | const u8 *pbmul; /* P multiplier table for B data */ |
| 27 | const u8 *qmul; /* Q multiplier table (for both) */ |
| 28 | int i; |
| 29 | |
| 30 | p = (u8 *)ptrs[disks-2]; |
| 31 | q = (u8 *)ptrs[disks-1]; |
| 32 | |
| 33 | /* Compute syndrome with zero for the missing data pages |
| 34 | Use the dead data pages as temporary storage for |
| 35 | delta p and delta q */ |
| 36 | dp = (u8 *)ptrs[faila]; |
| 37 | ptrs[faila] = (void *)raid6_empty_zero_page; |
| 38 | ptrs[disks-2] = dp; |
| 39 | dq = (u8 *)ptrs[failb]; |
| 40 | ptrs[failb] = (void *)raid6_empty_zero_page; |
| 41 | ptrs[disks-1] = dq; |
| 42 | |
| 43 | raid6_call.gen_syndrome(disks, bytes, ptrs); |
| 44 | |
| 45 | /* Restore pointer table */ |
| 46 | ptrs[faila] = dp; |
| 47 | ptrs[failb] = dq; |
| 48 | ptrs[disks-2] = p; |
| 49 | ptrs[disks-1] = q; |
| 50 | |
| 51 | /* Now, pick the proper data tables */ |
| 52 | pbmul = raid6_gfmul[raid6_gfexi[failb-faila]]; |
| 53 | qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]]; |
| 54 | |
| 55 | /* Now do it... */ |
| 56 | while (bytes) { |
| 57 | xor_block(dp, p); |
| 58 | xor_block(dq, q); |
| 59 | for (i = 0; i < 256; i++) |
| 60 | dq[i] = pbmul[dp[i]] ^ qmul[dq[i]]; |
| 61 | xor_block(dp, dq); |
| 62 | p += 256; |
| 63 | q += 256; |
| 64 | dp += 256; |
| 65 | dq += 256; |
| 66 | bytes -= 256; |
| 67 | } |
| 68 | } |
| 69 | |
| 70 | /* Recover failure of one data block plus the P block */ |
| 71 | static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila, |
| 72 | void **ptrs) |
| 73 | { |
| 74 | u8 *p, *q, *dq; |
| 75 | const u8 *qmul; /* Q multiplier table */ |
| 76 | int i; |
| 77 | |
| 78 | p = (u8 *)ptrs[disks-2]; |
| 79 | q = (u8 *)ptrs[disks-1]; |
| 80 | |
| 81 | /* Compute syndrome with zero for the missing data page |
| 82 | Use the dead data page as temporary storage for delta q */ |
| 83 | dq = (u8 *)ptrs[faila]; |
| 84 | ptrs[faila] = (void *)raid6_empty_zero_page; |
| 85 | ptrs[disks-1] = dq; |
| 86 | |
| 87 | raid6_call.gen_syndrome(disks, bytes, ptrs); |
| 88 | |
| 89 | /* Restore pointer table */ |
| 90 | ptrs[faila] = dq; |
| 91 | ptrs[disks-1] = q; |
| 92 | |
| 93 | /* Now, pick the proper data tables */ |
| 94 | qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]]; |
| 95 | |
| 96 | /* Now do it... */ |
| 97 | while (bytes) { |
| 98 | xor_block(dq, q); |
| 99 | for (i = 0; i < 256; i++) |
| 100 | dq[i] = qmul[dq[i]]; |
| 101 | xor_block(p, dq); |
| 102 | p += 256; |
| 103 | q += 256; |
| 104 | dq += 256; |
| 105 | bytes -= 256; |
| 106 | } |
| 107 | } |
| 108 | |
| 109 | |
| 110 | const struct raid6_recov_calls raid6_recov_s390xc = { |
| 111 | .data2 = raid6_2data_recov_s390xc, |
| 112 | .datap = raid6_datap_recov_s390xc, |
| 113 | .valid = NULL, |
| 114 | .name = "s390xc", |
| 115 | .priority = 1, |
| 116 | }; |