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lib/raid6: add ARM-NEON accelerated syndrome calculation

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Rebased/reworked a patch contributed by Rob Herring that uses
NEON intrinsics to perform the RAID-6 syndrome calculations.
It uses the existing unroll.awk code to generate several
unrolled versions of which the best performing one is selected
at boot time.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: hpa@linux.intel.com
This commit is contained in:
Ard Biesheuvel 2013-05-16 17:20:32 +02:00
parent 01956597cb
commit 7d11965ddb
7 changed files with 215 additions and 1 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
include/linux/raid/pq.h
View file

@ -114,6 +114,11 @@ 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_calls raid6_neonx1;
extern const struct raid6_calls raid6_neonx2;
extern const struct raid6_calls raid6_neonx4;
extern const struct raid6_calls raid6_neonx8;
/* Algorithm list */
extern const struct raid6_calls * const raid6_algos[];
extern const struct raid6_recov_calls *const raid6_recov_algos[];

1
lib/raid6/.gitignore vendored
View file

@ -2,3 +2,4 @@ mktables
altivec*.c
int*.c
tables.c
neon?.c

40
lib/raid6/Makefile
View file

@ -5,6 +5,7 @@ raid6_pq-y += algos.o recov.o tables.o int1.o int2.o int4.o \
raid6_pq-$(CONFIG_X86) += recov_ssse3.o recov_avx2.o mmx.o sse1.o sse2.o avx2.o
raid6_pq-$(CONFIG_ALTIVEC) += altivec1.o altivec2.o altivec4.o altivec8.o
raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o
hostprogs-y += mktables
@ -16,6 +17,21 @@ ifeq ($(CONFIG_ALTIVEC),y)
altivec_flags := -maltivec -mabi=altivec
endif
# The GCC option -ffreestanding is required in order to compile code containing
# ARM/NEON intrinsics in a non C99-compliant environment (such as the kernel)
ifeq ($(CONFIG_KERNEL_MODE_NEON),y)
NEON_FLAGS := -ffreestanding
ifeq ($(ARCH),arm)
NEON_FLAGS += -mfloat-abi=softfp -mfpu=neon
endif
ifeq ($(ARCH),arm64)
CFLAGS_REMOVE_neon1.o += -mgeneral-regs-only
CFLAGS_REMOVE_neon2.o += -mgeneral-regs-only
CFLAGS_REMOVE_neon4.o += -mgeneral-regs-only
CFLAGS_REMOVE_neon8.o += -mgeneral-regs-only
endif
endif
targets += int1.c
$(obj)/int1.c: UNROLL := 1
$(obj)/int1.c: $(src)/int.uc $(src)/unroll.awk FORCE
@ -70,6 +86,30 @@ $(obj)/altivec8.c: UNROLL := 8
$(obj)/altivec8.c: $(src)/altivec.uc $(src)/unroll.awk FORCE
$(call if_changed,unroll)
CFLAGS_neon1.o += $(NEON_FLAGS)
targets += neon1.c
$(obj)/neon1.c: UNROLL := 1
$(obj)/neon1.c: $(src)/neon.uc $(src)/unroll.awk FORCE
$(call if_changed,unroll)
CFLAGS_neon2.o += $(NEON_FLAGS)
targets += neon2.c
$(obj)/neon2.c: UNROLL := 2
$(obj)/neon2.c: $(src)/neon.uc $(src)/unroll.awk FORCE
$(call if_changed,unroll)
CFLAGS_neon4.o += $(NEON_FLAGS)
targets += neon4.c
$(obj)/neon4.c: UNROLL := 4
$(obj)/neon4.c: $(src)/neon.uc $(src)/unroll.awk FORCE
$(call if_changed,unroll)
CFLAGS_neon8.o += $(NEON_FLAGS)
targets += neon8.c
$(obj)/neon8.c: UNROLL := 8
$(obj)/neon8.c: $(src)/neon.uc $(src)/unroll.awk FORCE
$(call if_changed,unroll)
quiet_cmd_mktable = TABLE $@
cmd_mktable = $(obj)/mktables > $@ || ( rm -f $@ && exit 1 )

6
lib/raid6/algos.c
View file

@ -70,6 +70,12 @@ const struct raid6_calls * const raid6_algos[] = {
&raid6_intx2,
&raid6_intx4,
&raid6_intx8,
#ifdef CONFIG_KERNEL_MODE_NEON
&raid6_neonx1,
&raid6_neonx2,
&raid6_neonx4,
&raid6_neonx8,
#endif
NULL
};

58
lib/raid6/neon.c Normal file
View file

@ -0,0 +1,58 @@
/*
* linux/lib/raid6/neon.c - RAID6 syndrome calculation using ARM NEON intrinsics
*
* Copyright (C) 2013 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 version 2 as
* published by the Free Software Foundation.
*/
#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
/*
* There are 2 reasons these wrappers are kept in a separate compilation unit
* from the actual implementations in neonN.c (generated from neon.uc by
* unroll.awk):
* - the actual implementations use NEON intrinsics, and the GCC support header
* (arm_neon.h) is not fully compatible (type wise) with the kernel;
* - the neonN.c files are compiled with -mfpu=neon and optimization enabled,
* and we have to make sure that we never use *any* NEON/VFP instructions
* outside a kernel_neon_begin()/kernel_neon_end() pair.
*/
#define RAID6_NEON_WRAPPER(_n) \
static void raid6_neon ## _n ## _gen_syndrome(int disks, \
size_t bytes, void **ptrs) \
{ \
void raid6_neon ## _n ## _gen_syndrome_real(int, \
unsigned long, void**); \
kernel_neon_begin(); \
raid6_neon ## _n ## _gen_syndrome_real(disks, \
(unsigned long)bytes, ptrs); \
kernel_neon_end(); \
} \
struct raid6_calls const raid6_neonx ## _n = { \
raid6_neon ## _n ## _gen_syndrome, \
raid6_have_neon, \
"neonx" #_n, \
0 \
}
static int raid6_have_neon(void)
{
return cpu_has_neon();
}
RAID6_NEON_WRAPPER(1);
RAID6_NEON_WRAPPER(2);
RAID6_NEON_WRAPPER(4);
RAID6_NEON_WRAPPER(8);

80
lib/raid6/neon.uc Normal file
View file

@ -0,0 +1,80 @@
/* -----------------------------------------------------------------------
*
* neon.uc - RAID-6 syndrome calculation using ARM NEON instructions
*
* Copyright (C) 2012 Rob Herring
*
* Based on altivec.uc:
* Copyright 2002-2004 H. Peter Anvin - All Rights Reserved
*
* 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, Inc., 53 Temple Place Ste 330,
* Boston MA 02111-1307, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* neon$#.c
*
* $#-way unrolled NEON intrinsics math RAID-6 instruction set
*
* This file is postprocessed using unroll.awk
*/
#include <arm_neon.h>
typedef uint8x16_t unative_t;
#define NBYTES(x) ((unative_t){x,x,x,x, x,x,x,x, x,x,x,x, x,x,x,x})
#define NSIZE sizeof(unative_t)
/*
* The SHLBYTE() operation shifts each byte left by 1, *not*
* rolling over into the next byte
*/
static inline unative_t SHLBYTE(unative_t v)
{
return vshlq_n_u8(v, 1);
}
/*
* The MASK() operation returns 0xFF in any byte for which the high
* bit is 1, 0x00 for any byte for which the high bit is 0.
*/
static inline unative_t MASK(unative_t v)
{
const uint8x16_t temp = NBYTES(0);
return (unative_t)vcltq_s8((int8x16_t)v, (int8x16_t)temp);
}
void raid6_neon$#_gen_syndrome_real(int disks, unsigned long bytes, void **ptrs)
{
uint8_t **dptr = (uint8_t **)ptrs;
uint8_t *p, *q;
int d, z, z0;
register unative_t wd$$, wq$$, wp$$, w1$$, w2$$;
const unative_t x1d = NBYTES(0x1d);
z0 = disks - 3; /* Highest data disk */
p = dptr[z0+1]; /* XOR parity */
q = dptr[z0+2]; /* RS syndrome */
for ( d = 0 ; d < bytes ; d += NSIZE*$# ) {
wq$$ = wp$$ = vld1q_u8(&dptr[z0][d+$$*NSIZE]);
for ( z = z0-1 ; z >= 0 ; z-- ) {
wd$$ = vld1q_u8(&dptr[z][d+$$*NSIZE]);
wp$$ = veorq_u8(wp$$, wd$$);
w2$$ = MASK(wq$$);
w1$$ = SHLBYTE(wq$$);
w2$$ = vandq_u8(w2$$, x1d);
w1$$ = veorq_u8(w1$$, w2$$);
wq$$ = veorq_u8(w1$$, wd$$);
}
vst1q_u8(&p[d+NSIZE*$$], wp$$);
vst1q_u8(&q[d+NSIZE*$$], wq$$);
}
}

26
lib/raid6/test/Makefile
View file

@ -22,11 +22,23 @@ ifeq ($(ARCH),x86_64)
IS_X86 = yes
endif
ifeq ($(ARCH),arm)
CFLAGS += -I../../../arch/arm/include -mfpu=neon
HAS_NEON = yes
endif
ifeq ($(ARCH),arm64)
CFLAGS += -I../../../arch/arm64/include
HAS_NEON = yes
endif
ifeq ($(IS_X86),yes)
OBJS += mmx.o sse1.o sse2.o avx2.o recov_ssse3.o recov_avx2.o
CFLAGS += $(shell echo "vpbroadcastb %xmm0, %ymm1" | \
gcc -c -x assembler - >&/dev/null && \
rm ./-.o && echo -DCONFIG_AS_AVX2=1)
else ifeq ($(HAS_NEON),yes)
OBJS += neon.o neon1.o neon2.o neon4.o neon8.o
CFLAGS += -DCONFIG_KERNEL_MODE_NEON=1
else
HAS_ALTIVEC := $(shell echo -e '\#include <altivec.h>\nvector int a;' |\
gcc -c -x c - >&/dev/null && \
@ -55,6 +67,18 @@ raid6.a: $(OBJS)
raid6test: test.c raid6.a
$(CC) $(CFLAGS) -o raid6test $^
neon1.c: neon.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=1 < neon.uc > $@
neon2.c: neon.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=2 < neon.uc > $@
neon4.c: neon.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=4 < neon.uc > $@
neon8.c: neon.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=8 < neon.uc > $@
altivec1.c: altivec.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=1 < altivec.uc > $@
@ -89,7 +113,7 @@ tables.c: mktables
./mktables > tables.c
clean:
rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c tables.c raid6test
rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c neon*.c tables.c raid6test
spotless: clean
rm -f *~