lib/raid6/recov_s390xc.c

   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 };