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Commit 6ec4e251 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Catalin Marinas
Browse files

md/raid6: implement recovery using ARM NEON intrinsics 



Provide a NEON accelerated implementation of the recovery algorithm,
which supersedes the default byte-by-byte one.

Signed-off-by: default avatarArd Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 35129dde

include/linux/raid/pq.h

+1 −0
Original line number Diff line number Diff line
@@ -121,6 +121,7 @@ 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_avx512;

extern const struct raid6_recov_calls raid6_recov_s390xc;

extern const struct raid6_recov_calls raid6_recov_neon;



extern const struct raid6_calls raid6_neonx1;

extern const struct raid6_calls raid6_neonx2;

lib/raid6/Makefile

+3 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ raid6_pq-y += algos.o recov.o tables.o int1.o int2.o int4.o \ 


raid6_pq-$(CONFIG_X86) += recov_ssse3.o recov_avx2.o mmx.o sse1.o sse2.o avx2.o avx512.o recov_avx512.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_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o recov_neon.o recov_neon_inner.o

raid6_pq-$(CONFIG_TILEGX) += tilegx8.o

raid6_pq-$(CONFIG_S390) += s390vx8.o recov_s390xc.o
@@ -26,7 +26,9 @@ NEON_FLAGS := -ffreestanding 
ifeq ($(ARCH),arm)

NEON_FLAGS += -mfloat-abi=softfp -mfpu=neon

endif

CFLAGS_recov_neon_inner.o += $(NEON_FLAGS)

ifeq ($(ARCH),arm64)

CFLAGS_REMOVE_recov_neon_inner.o += -mgeneral-regs-only

CFLAGS_REMOVE_neon1.o += -mgeneral-regs-only

CFLAGS_REMOVE_neon2.o += -mgeneral-regs-only

CFLAGS_REMOVE_neon4.o += -mgeneral-regs-only

lib/raid6/algos.c

+3 −0
Original line number Diff line number Diff line
@@ -112,6 +112,9 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = { 
#endif

#ifdef CONFIG_S390

	&raid6_recov_s390xc,

#endif

#if defined(CONFIG_KERNEL_MODE_NEON)

	&raid6_recov_neon,

#endif

	&raid6_recov_intx1,

	NULL

lib/raid6/recov_neon.c

0 → 100644
+110 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2012 Intel Corporation

 * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; version 2

 * of the License.

 */



#include <linux/raid/pq.h>



#ifdef __KERNEL__

#include <asm/neon.h>

#else

#define kernel_neon_begin()

#define kernel_neon_end()

#define cpu_has_neon()		(1)

#endif



static int raid6_has_neon(void)

{

	return cpu_has_neon();

}



void __raid6_2data_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dp,

			      uint8_t *dq, const uint8_t *pbmul,

			      const uint8_t *qmul);



void __raid6_datap_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dq,

			      const uint8_t *qmul);



static void raid6_2data_recov_neon(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) */



	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_vgfmul[raid6_gfexi[failb-faila]];

	qmul  = raid6_vgfmul[raid6_gfinv[raid6_gfexp[faila] ^

					 raid6_gfexp[failb]]];



	kernel_neon_begin();

	__raid6_2data_recov_neon(bytes, p, q, dp, dq, pbmul, qmul);

	kernel_neon_end();

}



static void raid6_datap_recov_neon(int disks, size_t bytes, int faila,

		void **ptrs)

{

	u8 *p, *q, *dq;

	const u8 *qmul;		/* Q multiplier table */



	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_vgfmul[raid6_gfinv[raid6_gfexp[faila]]];



	kernel_neon_begin();

	__raid6_datap_recov_neon(bytes, p, q, dq, qmul);

	kernel_neon_end();

}



const struct raid6_recov_calls raid6_recov_neon = {

	.data2		= raid6_2data_recov_neon,

	.datap		= raid6_datap_recov_neon,

	.valid		= raid6_has_neon,

	.name		= "neon",

	.priority	= 10,

};

lib/raid6/recov_neon_inner.c

0 → 100644
+117 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2012 Intel Corporation

 * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; version 2

 * of the License.

 */



#include <arm_neon.h>



static const uint8x16_t x0f = {

	0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f,

	0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f,

};



#ifdef CONFIG_ARM

/*

 * AArch32 does not provide this intrinsic natively because it does not

 * implement the underlying instruction. AArch32 only provides a 64-bit

 * wide vtbl.8 instruction, so use that instead.

 */

static uint8x16_t vqtbl1q_u8(uint8x16_t a, uint8x16_t b)

{

	union {

		uint8x16_t	val;

		uint8x8x2_t	pair;

	} __a = { a };



	return vcombine_u8(vtbl2_u8(__a.pair, vget_low_u8(b)),

			   vtbl2_u8(__a.pair, vget_high_u8(b)));

}

#endif



void __raid6_2data_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dp,

			      uint8_t *dq, const uint8_t *pbmul,

			      const uint8_t *qmul)

{

	uint8x16_t pm0 = vld1q_u8(pbmul);

	uint8x16_t pm1 = vld1q_u8(pbmul + 16);

	uint8x16_t qm0 = vld1q_u8(qmul);

	uint8x16_t qm1 = vld1q_u8(qmul + 16);



	/*

	 * while ( bytes-- ) {

	 *	uint8_t px, qx, db;

	 *

	 *	px    = *p ^ *dp;

	 *	qx    = qmul[*q ^ *dq];

	 *	*dq++ = db = pbmul[px] ^ qx;

	 *	*dp++ = db ^ px;

	 *	p++; q++;

	 * }

	 */



	while (bytes) {

		uint8x16_t vx, vy, px, qx, db;



		px = veorq_u8(vld1q_u8(p), vld1q_u8(dp));

		vx = veorq_u8(vld1q_u8(q), vld1q_u8(dq));



		vy = (uint8x16_t)vshrq_n_s16((int16x8_t)vx, 4);

		vx = vqtbl1q_u8(qm0, vandq_u8(vx, x0f));

		vy = vqtbl1q_u8(qm1, vandq_u8(vy, x0f));

		qx = veorq_u8(vx, vy);



		vy = (uint8x16_t)vshrq_n_s16((int16x8_t)px, 4);

		vx = vqtbl1q_u8(pm0, vandq_u8(px, x0f));

		vy = vqtbl1q_u8(pm1, vandq_u8(vy, x0f));

		vx = veorq_u8(vx, vy);

		db = veorq_u8(vx, qx);



		vst1q_u8(dq, db);

		vst1q_u8(dp, veorq_u8(db, px));



		bytes -= 16;

		p += 16;

		q += 16;

		dp += 16;

		dq += 16;

	}

}



void __raid6_datap_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dq,

			      const uint8_t *qmul)

{

	uint8x16_t qm0 = vld1q_u8(qmul);

	uint8x16_t qm1 = vld1q_u8(qmul + 16);



	/*

	 * while (bytes--) {

	 *	*p++ ^= *dq = qmul[*q ^ *dq];

	 *	q++; dq++;

	 * }

	 */



	while (bytes) {

		uint8x16_t vx, vy;



		vx = veorq_u8(vld1q_u8(q), vld1q_u8(dq));



		vy = (uint8x16_t)vshrq_n_s16((int16x8_t)vx, 4);

		vx = vqtbl1q_u8(qm0, vandq_u8(vx, x0f));

		vy = vqtbl1q_u8(qm1, vandq_u8(vy, x0f));

		vx = veorq_u8(vx, vy);

		vy = veorq_u8(vx, vld1q_u8(p));



		vst1q_u8(dq, vx);

		vst1q_u8(p, vy);



		bytes -= 16;

		p += 16;

		q += 16;

		dq += 16;

	}

}