LXR linux/lib/raid6/recov

   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
  11static 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. */
  22static 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 */
  71static 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
 110const 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};
 117