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/export.h> |
10 | #include <linux/raid/pq.h> |
11 | |
12 | static inline void xor_block(u8 *p1, u8 *p2) |
13 | { |
14 | typedef struct { u8 _[256]; } addrtype; |
15 | |
16 | asm volatile( |
17 | " xc 0(256,%[p1]),0(%[p2])\n" |
18 | : "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2), |
19 | [p1] "a" (p1), [p2] "a" (p2) : "cc" ); |
20 | } |
21 | |
22 | /* Recover two failed data blocks. */ |
23 | static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila, |
24 | int failb, void **ptrs) |
25 | { |
26 | u8 *p, *q, *dp, *dq; |
27 | const u8 *pbmul; /* P multiplier table for B data */ |
28 | const u8 *qmul; /* Q multiplier table (for both) */ |
29 | int i; |
30 | |
31 | p = (u8 *)ptrs[disks-2]; |
32 | q = (u8 *)ptrs[disks-1]; |
33 | |
34 | /* Compute syndrome with zero for the missing data pages |
35 | Use the dead data pages as temporary storage for |
36 | delta p and delta q */ |
37 | dp = (u8 *)ptrs[faila]; |
38 | ptrs[faila] = (void *)raid6_empty_zero_page; |
39 | ptrs[disks-2] = dp; |
40 | dq = (u8 *)ptrs[failb]; |
41 | ptrs[failb] = (void *)raid6_empty_zero_page; |
42 | ptrs[disks-1] = dq; |
43 | |
44 | raid6_call.gen_syndrome(disks, bytes, ptrs); |
45 | |
46 | /* Restore pointer table */ |
47 | ptrs[faila] = dp; |
48 | ptrs[failb] = dq; |
49 | ptrs[disks-2] = p; |
50 | ptrs[disks-1] = q; |
51 | |
52 | /* Now, pick the proper data tables */ |
53 | pbmul = raid6_gfmul[raid6_gfexi[failb-faila]]; |
54 | qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]]; |
55 | |
56 | /* Now do it... */ |
57 | while (bytes) { |
58 | xor_block(p1: dp, p2: p); |
59 | xor_block(p1: dq, p2: q); |
60 | for (i = 0; i < 256; i++) |
61 | dq[i] = pbmul[dp[i]] ^ qmul[dq[i]]; |
62 | xor_block(p1: dp, p2: dq); |
63 | p += 256; |
64 | q += 256; |
65 | dp += 256; |
66 | dq += 256; |
67 | bytes -= 256; |
68 | } |
69 | } |
70 | |
71 | /* Recover failure of one data block plus the P block */ |
72 | static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila, |
73 | void **ptrs) |
74 | { |
75 | u8 *p, *q, *dq; |
76 | const u8 *qmul; /* Q multiplier table */ |
77 | int i; |
78 | |
79 | p = (u8 *)ptrs[disks-2]; |
80 | q = (u8 *)ptrs[disks-1]; |
81 | |
82 | /* Compute syndrome with zero for the missing data page |
83 | Use the dead data page as temporary storage for delta q */ |
84 | dq = (u8 *)ptrs[faila]; |
85 | ptrs[faila] = (void *)raid6_empty_zero_page; |
86 | ptrs[disks-1] = dq; |
87 | |
88 | raid6_call.gen_syndrome(disks, bytes, ptrs); |
89 | |
90 | /* Restore pointer table */ |
91 | ptrs[faila] = dq; |
92 | ptrs[disks-1] = q; |
93 | |
94 | /* Now, pick the proper data tables */ |
95 | qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]]; |
96 | |
97 | /* Now do it... */ |
98 | while (bytes) { |
99 | xor_block(p1: dq, p2: q); |
100 | for (i = 0; i < 256; i++) |
101 | dq[i] = qmul[dq[i]]; |
102 | xor_block(p1: p, p2: dq); |
103 | p += 256; |
104 | q += 256; |
105 | dq += 256; |
106 | bytes -= 256; |
107 | } |
108 | } |
109 | |
110 | |
111 | const struct raid6_recov_calls raid6_recov_s390xc = { |
112 | .data2 = raid6_2data_recov_s390xc, |
113 | .datap = raid6_datap_recov_s390xc, |
114 | .valid = NULL, |
115 | .name = "s390xc" , |
116 | .priority = 1, |
117 | }; |
118 | |