From 751ba79cc552c146595cd439b21c4ff8998c3b69 Mon Sep 17 00:00:00 2001
From: Matt Brown <matthew.brown.dev@gmail.com>
Date: Fri, 4 Aug 2017 13:42:32 +1000
Subject: [PATCH] lib/raid6/altivec: Add vpermxor implementation for raid6 Q
syndrome
Git-commit: 751ba79cc552c146595cd439b21c4ff8998c3b69
Patch-mainline: v4.17-rc1
References: bsc#1111974 bsc#1166003
This patch uses the vpermxor instruction to optimise the raid6 Q
syndrome. This instruction was made available with POWER8, ISA version
2.07. It allows for both vperm and vxor instructions to be done in a
single instruction. This has been tested for correctness on a ppc64le
vm with a basic RAID6 setup containing 5 drives.
The performance benchmarks are from the raid6test in the
/lib/raid6/test directory. These results are from an IBM Firestone
machine with ppc64le architecture. The benchmark results show a 35%
speed increase over the best existing algorithm for powerpc (altivec).
The raid6test has also been run on a big-endian ppc64 vm to ensure it
also works for big-endian architectures.
Performance benchmarks:
raid6: altivecx4 gen() 18773 MB/s
raid6: altivecx8 gen() 19438 MB/s
raid6: vpermxor4 gen() 25112 MB/s
raid6: vpermxor8 gen() 26279 MB/s
Signed-off-by: Matt Brown <matthew.brown.dev@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
[mpe: Add VPERMXOR macro so we can build with old binutils]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Coly Li <colyli@suse.de>
---
arch/powerpc/include/asm/ppc-opcode.h | 6 +
include/linux/raid/pq.h | 4 +
lib/raid6/.gitignore | 1
lib/raid6/Makefile | 27 ++++++++
lib/raid6/algos.c | 4 +
lib/raid6/test/Makefile | 17 ++++-
lib/raid6/vpermxor.uc | 105 ++++++++++++++++++++++++++++++++++
7 files changed, 161 insertions(+), 3 deletions(-)
create mode 100644 lib/raid6/vpermxor.uc
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -267,6 +267,7 @@
#define PPC_INST_TLBSRX_DOT 0x7c0006a5
#define PPC_INST_VPMSUMW 0x10000488
#define PPC_INST_VPMSUMD 0x100004c8
+#define PPC_INST_VPERMXOR 0x1000002d
#define PPC_INST_XXLOR 0xf0000490
#define PPC_INST_XXSWAPD 0xf0000250
#define PPC_INST_XVCPSGNDP 0xf0000780
@@ -501,6 +502,11 @@
#define XVCPSGNDP(t, a, b) stringify_in_c(.long (PPC_INST_XVCPSGNDP | \
VSX_XX3((t), (a), (b))))
+#define VPERMXOR(vrt, vra, vrb, vrc) \
+ stringify_in_c(.long (PPC_INST_VPERMXOR | \
+ ___PPC_RT(vrt) | ___PPC_RA(vra) | \
+ ___PPC_RB(vrb) | (((vrc) & 0x1f) << 6)))
+
#define PPC_NAP stringify_in_c(.long PPC_INST_NAP)
#define PPC_SLEEP stringify_in_c(.long PPC_INST_SLEEP)
#define PPC_WINKLE stringify_in_c(.long PPC_INST_WINKLE)
--- a/include/linux/raid/pq.h
+++ b/include/linux/raid/pq.h
@@ -106,6 +106,10 @@ extern const struct raid6_calls raid6_av
extern const struct raid6_calls raid6_avx512x2;
extern const struct raid6_calls raid6_avx512x4;
extern const struct raid6_calls raid6_s390vx8;
+extern const struct raid6_calls raid6_vpermxor1;
+extern const struct raid6_calls raid6_vpermxor2;
+extern const struct raid6_calls raid6_vpermxor4;
+extern const struct raid6_calls raid6_vpermxor8;
struct raid6_recov_calls {
void (*data2)(int, size_t, int, int, void **);
--- a/lib/raid6/.gitignore
+++ b/lib/raid6/.gitignore
@@ -4,3 +4,4 @@ int*.c
tables.c
neon?.c
s390vx?.c
+vpermxor*.c
--- a/lib/raid6/Makefile
+++ b/lib/raid6/Makefile
@@ -4,7 +4,8 @@ raid6_pq-y += algos.o recov.o tables.o i
int8.o int16.o int32.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-$(CONFIG_ALTIVEC) += altivec1.o altivec2.o altivec4.o altivec8.o \
+ vpermxor1.o vpermxor2.o vpermxor4.o vpermxor8.o
raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o recov_neon.o recov_neon_inner.o
raid6_pq-$(CONFIG_S390) += s390vx8.o recov_s390xc.o
@@ -89,6 +90,30 @@ $(obj)/altivec8.c: UNROLL := 8
$(obj)/altivec8.c: $(src)/altivec.uc $(src)/unroll.awk FORCE
$(call if_changed,unroll)
+CFLAGS_vpermxor1.o += $(altivec_flags)
+targets += vpermxor1.c
+$(obj)/vpermxor1.c: UNROLL := 1
+$(obj)/vpermxor1.c: $(src)/vpermxor.uc $(src)/unroll.awk FORCE
+ $(call if_changed,unroll)
+
+CFLAGS_vpermxor2.o += $(altivec_flags)
+targets += vpermxor2.c
+$(obj)/vpermxor2.c: UNROLL := 2
+$(obj)/vpermxor2.c: $(src)/vpermxor.uc $(src)/unroll.awk FORCE
+ $(call if_changed,unroll)
+
+CFLAGS_vpermxor4.o += $(altivec_flags)
+targets += vpermxor4.c
+$(obj)/vpermxor4.c: UNROLL := 4
+$(obj)/vpermxor4.c: $(src)/vpermxor.uc $(src)/unroll.awk FORCE
+ $(call if_changed,unroll)
+
+CFLAGS_vpermxor8.o += $(altivec_flags)
+targets += vpermxor8.c
+$(obj)/vpermxor8.c: UNROLL := 8
+$(obj)/vpermxor8.c: $(src)/vpermxor.uc $(src)/unroll.awk FORCE
+ $(call if_changed,unroll)
+
CFLAGS_neon1.o += $(NEON_FLAGS)
targets += neon1.c
$(obj)/neon1.c: UNROLL := 1
--- a/lib/raid6/algos.c
+++ b/lib/raid6/algos.c
@@ -74,6 +74,10 @@ const struct raid6_calls * const raid6_a
&raid6_altivec2,
&raid6_altivec4,
&raid6_altivec8,
+ &raid6_vpermxor1,
+ &raid6_vpermxor2,
+ &raid6_vpermxor4,
+ &raid6_vpermxor8,
#endif
#if defined(CONFIG_S390)
&raid6_s390vx8,
--- a/lib/raid6/test/Makefile
+++ b/lib/raid6/test/Makefile
@@ -47,7 +47,8 @@ else
gcc -c -x c - >&/dev/null && \
rm ./-.o && echo yes)
ifeq ($(HAS_ALTIVEC),yes)
- OBJS += altivec1.o altivec2.o altivec4.o altivec8.o
+ OBJS += altivec1.o altivec2.o altivec4.o altivec8.o \
+ vpermxor1.o vpermxor2.o vpermxor4.o vpermxor8.o
endif
endif
@@ -94,6 +95,18 @@ altivec4.c: altivec.uc ../unroll.awk
altivec8.c: altivec.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=8 < altivec.uc > $@
+vpermxor1.c: vpermxor.uc ../unroll.awk
+ $(AWK) ../unroll.awk -vN=1 < vpermxor.uc > $@
+
+vpermxor2.c: vpermxor.uc ../unroll.awk
+ $(AWK) ../unroll.awk -vN=2 < vpermxor.uc > $@
+
+vpermxor4.c: vpermxor.uc ../unroll.awk
+ $(AWK) ../unroll.awk -vN=4 < vpermxor.uc > $@
+
+vpermxor8.c: vpermxor.uc ../unroll.awk
+ $(AWK) ../unroll.awk -vN=8 < vpermxor.uc > $@
+
int1.c: int.uc ../unroll.awk
$(AWK) ../unroll.awk -vN=1 < int.uc > $@
@@ -116,7 +129,7 @@ tables.c: mktables
./mktables > tables.c
clean:
- rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c neon*.c tables.c raid6test
+ rm -f *.o *.a mktables mktables.c *.uc int*.c altivec*.c vpermxor*.c neon*.c tables.c raid6test
spotless: clean
rm -f *~
--- /dev/null
+++ b/lib/raid6/vpermxor.uc
@@ -0,0 +1,105 @@
+/*
+ * Copyright 2017, Matt Brown, IBM Corp.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * vpermxor$#.c
+ *
+ * Based on H. Peter Anvin's paper - The mathematics of RAID-6
+ *
+ * $#-way unrolled portable integer math RAID-6 instruction set
+ * This file is postprocessed using unroll.awk
+ *
+ * vpermxor$#.c makes use of the vpermxor instruction to optimise the RAID6 Q
+ * syndrome calculations.
+ * This can be run on systems which have both Altivec and vpermxor instruction.
+ *
+ * This instruction was introduced in POWER8 - ISA v2.07.
+ */
+
+#include <linux/raid/pq.h>
+#ifdef CONFIG_ALTIVEC
+
+#include <altivec.h>
+#ifdef __KERNEL__
+#include <asm/cputable.h>
+#include <asm/ppc-opcode.h>
+#include <asm/switch_to.h>
+#endif
+
+typedef vector unsigned char unative_t;
+#define NSIZE sizeof(unative_t)
+
+static const vector unsigned char gf_low = {0x1e, 0x1c, 0x1a, 0x18, 0x16, 0x14,
+ 0x12, 0x10, 0x0e, 0x0c, 0x0a, 0x08,
+ 0x06, 0x04, 0x02,0x00};
+static const vector unsigned char gf_high = {0xfd, 0xdd, 0xbd, 0x9d, 0x7d, 0x5d,
+ 0x3d, 0x1d, 0xe0, 0xc0, 0xa0, 0x80,
+ 0x60, 0x40, 0x20, 0x00};
+
+static void noinline raid6_vpermxor$#_gen_syndrome_real(int disks, size_t bytes,
+ void **ptrs)
+{
+ u8 **dptr = (u8 **)ptrs;
+ u8 *p, *q;
+ int d, z, z0;
+ unative_t wp$$, wq$$, wd$$;
+
+ z0 = disks - 3; /* Highest data disk */
+ p = dptr[z0+1]; /* XOR parity */
+ q = dptr[z0+2]; /* RS syndrome */
+
+ for (d = 0; d < bytes; d += NSIZE*$#) {
+ wp$$ = wq$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
+
+ for (z = z0-1; z>=0; z--) {
+ wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
+ /* P syndrome */
+ wp$$ = vec_xor(wp$$, wd$$);
+
+ /* Q syndrome */
+ asm(VPERMXOR(%0,%1,%2,%3):"=v"(wq$$):"v"(gf_high), "v"(gf_low), "v"(wq$$));
+ wq$$ = vec_xor(wq$$, wd$$);
+ }
+ *(unative_t *)&p[d+NSIZE*$$] = wp$$;
+ *(unative_t *)&q[d+NSIZE*$$] = wq$$;
+ }
+}
+
+static void raid6_vpermxor$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
+{
+ preempt_disable();
+ enable_kernel_altivec();
+
+ raid6_vpermxor$#_gen_syndrome_real(disks, bytes, ptrs);
+
+ disable_kernel_altivec();
+ preempt_enable();
+}
+
+int raid6_have_altivec_vpermxor(void);
+#if $# == 1
+int raid6_have_altivec_vpermxor(void)
+{
+ /* Check if arch has both altivec and the vpermxor instructions */
+# ifdef __KERNEL__
+ return (cpu_has_feature(CPU_FTR_ALTIVEC_COMP) &&
+ cpu_has_feature(CPU_FTR_ARCH_207S));
+# else
+ return 1;
+#endif
+
+}
+#endif
+
+const struct raid6_calls raid6_vpermxor$# = {
+ raid6_vpermxor$#_gen_syndrome,
+ NULL,
+ raid6_have_altivec_vpermxor,
+ "vpermxor$#",
+ 0
+};
+#endif