2 * RAID-6 data recovery in dual failure mode based on the XC instruction.
4 * Copyright IBM Corp. 2016
5 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
8 #include <linux/export.h>
9 #include <linux/raid/pq.h>
11 static inline void xor_block(u8 *p1, u8 *p2)
13 typedef struct { u8 _[256]; } addrtype;
16 " xc 0(256,%[p1]),0(%[p2])\n"
17 : "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2),
18 [p1] "a" (p1), [p2] "a" (p2) : "cc");
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)
26 const u8 *pbmul; /* P multiplier table for B data */
27 const u8 *qmul; /* Q multiplier table (for both) */
30 p = (u8 *)ptrs[disks-2];
31 q = (u8 *)ptrs[disks-1];
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;
39 dq = (u8 *)ptrs[failb];
40 ptrs[failb] = (void *)raid6_empty_zero_page;
43 raid6_call.gen_syndrome(disks, bytes, ptrs);
45 /* Restore pointer table */
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]]];
59 for (i = 0; i < 256; i++)
60 dq[i] = pbmul[dp[i]] ^ qmul[dq[i]];
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,
75 const u8 *qmul; /* Q multiplier table */
78 p = (u8 *)ptrs[disks-2];
79 q = (u8 *)ptrs[disks-1];
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;
87 raid6_call.gen_syndrome(disks, bytes, ptrs);
89 /* Restore pointer table */
93 /* Now, pick the proper data tables */
94 qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
99 for (i = 0; i < 256; i++)
110 const struct raid6_recov_calls raid6_recov_s390xc = {
111 .data2 = raid6_2data_recov_s390xc,
112 .datap = raid6_datap_recov_s390xc,