linux-imx

// SPDX-License-Identifier: GPL-2.0

/*

 * RAID-6 data recovery in dual failure mode based on the XC instruction.

 *

 * Copyright IBM Corp. 2016

 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>

 */

​

#include <linux/export.h>

#include <linux/raid/pq.h>

​

static inline void xor_block(u8 *p1, u8 *p2)

{

    typedef struct { u8 _[256]; } addrtype;

​

    asm volatile(

        "   xc  0(256,%[p1]),0(%[p2])\n"

        : "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2),

          [p1] "a" (p1), [p2] "a" (p2) : "cc");

}

​

/* Recover two failed data blocks. */

static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila,

        int failb, void **ptrs)

{

    u8 *p, *q, *dp, *dq;

    const u8 *pbmul;    /* P multiplier table for B data */

    const u8 *qmul;     /* Q multiplier table (for both) */

    int i;

​

    p = (u8 *)ptrs[disks-2];

    q = (u8 *)ptrs[disks-1];

​

    /* Compute syndrome with zero for the missing data pages

       Use the dead data pages as temporary storage for

       delta p and delta q */

    dp = (u8 *)ptrs[faila];

    ptrs[faila] = (void *)raid6_empty_zero_page;

    ptrs[disks-2] = dp;

    dq = (u8 *)ptrs[failb];

    ptrs[failb] = (void *)raid6_empty_zero_page;

    ptrs[disks-1] = dq;

​

    raid6_call.gen_syndrome(disks, bytes, ptrs);

​

    /* Restore pointer table */

    ptrs[faila]   = dp;

    ptrs[failb]   = dq;

    ptrs[disks-2] = p;

    ptrs[disks-1] = q;

​

    /* Now, pick the proper data tables */

    pbmul = raid6_gfmul[raid6_gfexi[failb-faila]];

    qmul  = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]];

​

    /* Now do it... */

    while (bytes) {

        xor_block(dp, p);

        xor_block(dq, q);

        for (i = 0; i < 256; i++)

            dq[i] = pbmul[dp[i]] ^ qmul[dq[i]];

        xor_block(dp, dq);

        p += 256;