Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit f5b55fa1 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 7bac4f5b

include/linux/raid/pq.h

+1 −0
Original line number Diff line number Diff line
@@ -116,6 +116,7 @@ struct raid6_recov_calls { 
extern const struct raid6_recov_calls raid6_recov_intx1;

extern const struct raid6_recov_calls raid6_recov_ssse3;

extern const struct raid6_recov_calls raid6_recov_avx2;

extern const struct raid6_recov_calls raid6_recov_s390xc;



extern const struct raid6_calls raid6_neonx1;

extern const struct raid6_calls raid6_neonx2;

lib/raid6/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -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

lib/raid6/algos.c

+3 −0
Original line number Diff line number Diff line
@@ -97,6 +97,9 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = { 
#endif

#ifdef CONFIG_AS_SSSE3

	&raid6_recov_ssse3,

#endif

#ifdef CONFIG_S390

	&raid6_recov_s390xc,

#endif

	&raid6_recov_intx1,

	NULL

lib/raid6/recov_s390xc.c

0 → 100644
+116 −0
Original line number Diff line number Diff line 
/*

 * 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,

};