1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * RAID-6 data recovery in dual failure mode based on the XC instruction.
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * Copyright IBM Corp. 2016
6*4882a593Smuzhiyun * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
7*4882a593Smuzhiyun */
8*4882a593Smuzhiyun
9*4882a593Smuzhiyun #include <linux/export.h>
10*4882a593Smuzhiyun #include <linux/raid/pq.h>
11*4882a593Smuzhiyun
xor_block(u8 * p1,u8 * p2)12*4882a593Smuzhiyun static inline void xor_block(u8 *p1, u8 *p2)
13*4882a593Smuzhiyun {
14*4882a593Smuzhiyun typedef struct { u8 _[256]; } addrtype;
15*4882a593Smuzhiyun
16*4882a593Smuzhiyun asm volatile(
17*4882a593Smuzhiyun " xc 0(256,%[p1]),0(%[p2])\n"
18*4882a593Smuzhiyun : "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2),
19*4882a593Smuzhiyun [p1] "a" (p1), [p2] "a" (p2) : "cc");
20*4882a593Smuzhiyun }
21*4882a593Smuzhiyun
22*4882a593Smuzhiyun /* Recover two failed data blocks. */
raid6_2data_recov_s390xc(int disks,size_t bytes,int faila,int failb,void ** ptrs)23*4882a593Smuzhiyun static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila,
24*4882a593Smuzhiyun int failb, void **ptrs)
25*4882a593Smuzhiyun {
26*4882a593Smuzhiyun u8 *p, *q, *dp, *dq;
27*4882a593Smuzhiyun const u8 *pbmul; /* P multiplier table for B data */
28*4882a593Smuzhiyun const u8 *qmul; /* Q multiplier table (for both) */
29*4882a593Smuzhiyun int i;
30*4882a593Smuzhiyun
31*4882a593Smuzhiyun p = (u8 *)ptrs[disks-2];
32*4882a593Smuzhiyun q = (u8 *)ptrs[disks-1];
33*4882a593Smuzhiyun
34*4882a593Smuzhiyun /* Compute syndrome with zero for the missing data pages
35*4882a593Smuzhiyun Use the dead data pages as temporary storage for
36*4882a593Smuzhiyun delta p and delta q */
37*4882a593Smuzhiyun dp = (u8 *)ptrs[faila];
38*4882a593Smuzhiyun ptrs[faila] = (void *)raid6_empty_zero_page;
39*4882a593Smuzhiyun ptrs[disks-2] = dp;
40*4882a593Smuzhiyun dq = (u8 *)ptrs[failb];
41*4882a593Smuzhiyun ptrs[failb] = (void *)raid6_empty_zero_page;
42*4882a593Smuzhiyun ptrs[disks-1] = dq;
43*4882a593Smuzhiyun
44*4882a593Smuzhiyun raid6_call.gen_syndrome(disks, bytes, ptrs);
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun /* Restore pointer table */
47*4882a593Smuzhiyun ptrs[faila] = dp;
48*4882a593Smuzhiyun ptrs[failb] = dq;
49*4882a593Smuzhiyun ptrs[disks-2] = p;
50*4882a593Smuzhiyun ptrs[disks-1] = q;
51*4882a593Smuzhiyun
52*4882a593Smuzhiyun /* Now, pick the proper data tables */
53*4882a593Smuzhiyun pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];
54*4882a593Smuzhiyun qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];
55*4882a593Smuzhiyun
56*4882a593Smuzhiyun /* Now do it... */
57*4882a593Smuzhiyun while (bytes) {
58*4882a593Smuzhiyun xor_block(dp, p);
59*4882a593Smuzhiyun xor_block(dq, q);
60*4882a593Smuzhiyun for (i = 0; i < 256; i++)
61*4882a593Smuzhiyun dq[i] = pbmul[dp[i]] ^ qmul[dq[i]];
62*4882a593Smuzhiyun xor_block(dp, dq);
63*4882a593Smuzhiyun p += 256;
64*4882a593Smuzhiyun q += 256;
65*4882a593Smuzhiyun dp += 256;
66*4882a593Smuzhiyun dq += 256;
67*4882a593Smuzhiyun bytes -= 256;
68*4882a593Smuzhiyun }
69*4882a593Smuzhiyun }
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun /* Recover failure of one data block plus the P block */
raid6_datap_recov_s390xc(int disks,size_t bytes,int faila,void ** ptrs)72*4882a593Smuzhiyun static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila,
73*4882a593Smuzhiyun void **ptrs)
74*4882a593Smuzhiyun {
75*4882a593Smuzhiyun u8 *p, *q, *dq;
76*4882a593Smuzhiyun const u8 *qmul; /* Q multiplier table */
77*4882a593Smuzhiyun int i;
78*4882a593Smuzhiyun
79*4882a593Smuzhiyun p = (u8 *)ptrs[disks-2];
80*4882a593Smuzhiyun q = (u8 *)ptrs[disks-1];
81*4882a593Smuzhiyun
82*4882a593Smuzhiyun /* Compute syndrome with zero for the missing data page
83*4882a593Smuzhiyun Use the dead data page as temporary storage for delta q */
84*4882a593Smuzhiyun dq = (u8 *)ptrs[faila];
85*4882a593Smuzhiyun ptrs[faila] = (void *)raid6_empty_zero_page;
86*4882a593Smuzhiyun ptrs[disks-1] = dq;
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun raid6_call.gen_syndrome(disks, bytes, ptrs);
89*4882a593Smuzhiyun
90*4882a593Smuzhiyun /* Restore pointer table */
91*4882a593Smuzhiyun ptrs[faila] = dq;
92*4882a593Smuzhiyun ptrs[disks-1] = q;
93*4882a593Smuzhiyun
94*4882a593Smuzhiyun /* Now, pick the proper data tables */
95*4882a593Smuzhiyun qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
96*4882a593Smuzhiyun
97*4882a593Smuzhiyun /* Now do it... */
98*4882a593Smuzhiyun while (bytes) {
99*4882a593Smuzhiyun xor_block(dq, q);
100*4882a593Smuzhiyun for (i = 0; i < 256; i++)
101*4882a593Smuzhiyun dq[i] = qmul[dq[i]];
102*4882a593Smuzhiyun xor_block(p, dq);
103*4882a593Smuzhiyun p += 256;
104*4882a593Smuzhiyun q += 256;
105*4882a593Smuzhiyun dq += 256;
106*4882a593Smuzhiyun bytes -= 256;
107*4882a593Smuzhiyun }
108*4882a593Smuzhiyun }
109*4882a593Smuzhiyun
110*4882a593Smuzhiyun
111*4882a593Smuzhiyun const struct raid6_recov_calls raid6_recov_s390xc = {
112*4882a593Smuzhiyun .data2 = raid6_2data_recov_s390xc,
113*4882a593Smuzhiyun .datap = raid6_datap_recov_s390xc,
114*4882a593Smuzhiyun .valid = NULL,
115*4882a593Smuzhiyun .name = "s390xc",
116*4882a593Smuzhiyun .priority = 1,
117*4882a593Smuzhiyun };
118