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authorMartin Schwidefsky <schwidefsky@de.ibm.com>2016-08-31 09:27:35 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2016-09-01 16:13:25 +0200
commitf5b55fa1f81d518925d68b50d2316850c525d1ad (patch)
treec4a75615884dff7236b788a774fdfb04892a3bfe /lib/raid6
parent7bac4f5b8e3a607f7ba1d3a652f5922a657fa9e8 (diff)
RAID/s390: provide raid6 recovery optimization
The XC instruction can be used to improve the speed of the raid6 recovery. The loops now operate on blocks of 256 bytes. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'lib/raid6')
-rw-r--r--lib/raid6/Makefile2
-rw-r--r--lib/raid6/algos.c3
-rw-r--r--lib/raid6/recov_s390xc.c116
3 files changed, 120 insertions, 1 deletions
diff --git a/lib/raid6/Makefile b/lib/raid6/Makefile
index 667b9607f8c0..29f503ebfd60 100644
--- a/lib/raid6/Makefile
+++ b/lib/raid6/Makefile
@@ -7,7 +7,7 @@ raid6_pq-$(CONFIG_X86) += recov_ssse3.o recov_avx2.o mmx.o sse1.o sse2.o avx2.o
raid6_pq-$(CONFIG_ALTIVEC) += altivec1.o altivec2.o altivec4.o altivec8.o
raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o
raid6_pq-$(CONFIG_TILEGX) += tilegx8.o
-raid6_pq-$(CONFIG_S390) += s390vx8.o
+raid6_pq-$(CONFIG_S390) += s390vx8.o recov_s390xc.o
hostprogs-y += mktables
diff --git a/lib/raid6/algos.c b/lib/raid6/algos.c
index e1923b602bbc..592ff49df47d 100644
--- a/lib/raid6/algos.c
+++ b/lib/raid6/algos.c
@@ -98,6 +98,9 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = {
#ifdef CONFIG_AS_SSSE3
&raid6_recov_ssse3,
#endif
+#ifdef CONFIG_S390
+ &raid6_recov_s390xc,
+#endif
&raid6_recov_intx1,
NULL
};
diff --git a/lib/raid6/recov_s390xc.c b/lib/raid6/recov_s390xc.c
new file mode 100644
index 000000000000..b042dac826cc
--- /dev/null
+++ b/lib/raid6/recov_s390xc.c
@@ -0,0 +1,116 @@
+/*
+ * 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;
+ q += 256;
+ dp += 256;
+ dq += 256;
+ bytes -= 256;
+ }
+}
+
+/* Recover failure of one data block plus the P block */
+static void raid6_datap_recov_s390xc(int disks, size_t bytes, int faila,
+ void **ptrs)
+{
+ u8 *p, *q, *dq;
+ const u8 *qmul; /* Q multiplier table */
+ int i;
+
+ p = (u8 *)ptrs[disks-2];
+ q = (u8 *)ptrs[disks-1];
+
+ /* Compute syndrome with zero for the missing data page
+ Use the dead data page as temporary storage for delta q */
+ dq = (u8 *)ptrs[faila];
+ ptrs[faila] = (void *)raid6_empty_zero_page;
+ ptrs[disks-1] = dq;
+
+ raid6_call.gen_syndrome(disks, bytes, ptrs);
+
+ /* Restore pointer table */
+ ptrs[faila] = dq;
+ ptrs[disks-1] = q;
+
+ /* Now, pick the proper data tables */
+ qmul = raid6_gfmul[raid6_gfinv[raid6_gfexp[faila]]];
+
+ /* Now do it... */
+ while (bytes) {
+ xor_block(dq, q);
+ for (i = 0; i < 256; i++)
+ dq[i] = qmul[dq[i]];
+ xor_block(p, dq);
+ p += 256;
+ q += 256;
+ dq += 256;
+ bytes -= 256;
+ }
+}
+
+
+const struct raid6_recov_calls raid6_recov_s390xc = {
+ .data2 = raid6_2data_recov_s390xc,
+ .datap = raid6_datap_recov_s390xc,
+ .valid = NULL,
+ .name = "s390xc",
+ .priority = 1,
+};