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117 lines
2.7 KiB
117 lines
2.7 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* RAID-6 data recovery in dual failure mode based on the XC instruction. |
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* |
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* Copyright IBM Corp. 2016 |
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* Author(s): Martin Schwidefsky <[email protected]> |
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*/ |
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#include <linux/export.h> |
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#include <linux/raid/pq.h> |
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static inline void xor_block(u8 *p1, u8 *p2) |
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{ |
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typedef struct { u8 _[256]; } addrtype; |
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asm volatile( |
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" xc 0(256,%[p1]),0(%[p2])\n" |
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: "+m" (*(addrtype *) p1) : "m" (*(addrtype *) p2), |
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[p1] "a" (p1), [p2] "a" (p2) : "cc"); |
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} |
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/* Recover two failed data blocks. */ |
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static void raid6_2data_recov_s390xc(int disks, size_t bytes, int faila, |
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int failb, void **ptrs) |
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{ |
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u8 *p, *q, *dp, *dq; |
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const u8 *pbmul; /* P multiplier table for B data */ |
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const u8 *qmul; /* Q multiplier table (for both) */ |
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int i; |
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p = (u8 *)ptrs[disks-2]; |
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q = (u8 *)ptrs[disks-1]; |
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/* Compute syndrome with zero for the missing data pages |
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Use the dead data pages as temporary storage for |
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delta p and delta q */ |
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dp = (u8 *)ptrs[faila]; |
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ptrs[faila] = (void *)raid6_empty_zero_page; |
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ptrs[disks-2] = dp; |
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dq = (u8 *)ptrs[failb]; |
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ptrs[failb] = (void *)raid6_empty_zero_page; |
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ptrs[disks-1] = dq; |
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raid6_call.gen_syndrome(disks, bytes, ptrs); |
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/* Restore pointer table */ |
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ptrs[faila] = dp; |
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ptrs[failb] = dq; |
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ptrs[disks-2] = p; |
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ptrs[disks-1] = q; |
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/* Now, pick the proper data tables */ |
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pbmul = raid6_gfmul[raid6_gfexi[failb-faila]]; |
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qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]^raid6_gfexp[failb]]]; |
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/* Now do it... */ |
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while (bytes) { |
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xor_block(dp, p); |
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xor_block(dq, q); |
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for (i = 0; i < 256; i++) |
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dq[i] = pbmul[dp[i]] ^ qmul[dq[i]]; |
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xor_block(dp, dq); |
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p += 256; |
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q += 256; |
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dp += 256; |
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dq += 256; |
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bytes -= 256; |
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} |
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} |
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/* Recover failure of one data block plus the P block */ |
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static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila, |
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void **ptrs) |
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{ |
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u8 *p, *q, *dq; |
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const u8 *qmul; /* Q multiplier table */ |
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int i; |
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p = (u8 *)ptrs[disks-2]; |
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q = (u8 *)ptrs[disks-1]; |
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/* Compute syndrome with zero for the missing data page |
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Use the dead data page as temporary storage for delta q */ |
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dq = (u8 *)ptrs[faila]; |
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ptrs[faila] = (void *)raid6_empty_zero_page; |
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ptrs[disks-1] = dq; |
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raid6_call.gen_syndrome(disks, bytes, ptrs); |
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/* Restore pointer table */ |
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ptrs[faila] = dq; |
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ptrs[disks-1] = q; |
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/* Now, pick the proper data tables */ |
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qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]]; |
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/* Now do it... */ |
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while (bytes) { |
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xor_block(dq, q); |
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for (i = 0; i < 256; i++) |
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dq[i] = qmul[dq[i]]; |
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xor_block(p, dq); |
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p += 256; |
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q += 256; |
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dq += 256; |
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bytes -= 256; |
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} |
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} |
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const struct raid6_recov_calls raid6_recov_s390xc = { |
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.data2 = raid6_2data_recov_s390xc, |
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.datap = raid6_datap_recov_s390xc, |
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.valid = NULL, |
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.name = "s390xc", |
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.priority = 1, |
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};
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