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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.

Ard Biesheuvel committed 9 years ago

Commit 6ec4e251 parent 35129dd5 files · +234 −1Browse files

Unified · Split

5 files
  1. include/linux/raid/pq.h +1 −0
  2. lib/raid6/Makefile +3 −1
  3. lib/raid6/algos.c +3 −0
  4. lib/raid6/recov_neon.c +110 −0
  5. lib/raid6/recov_neon_inner.c +117 −0
include/linux/raid/pq.h+1−0
@@ -121,6 +121,7 @@ extern const struct raid6_recov_calls raid6_recov_ssse3; · 120 unmodified lines
121121 extern const struct raid6_recov_calls raid6_recov_avx2;
122122 extern const struct raid6_recov_calls raid6_recov_avx512;
123123 extern const struct raid6_recov_calls raid6_recov_s390xc;
124+extern const struct raid6_recov_calls raid6_recov_neon;
124125
125126 extern const struct raid6_calls raid6_neonx1;
126127 extern const struct raid6_calls raid6_neonx2;
lib/raid6/Makefile+3−1
@@ -5,7 +5,7 @@ raid6_pq-y += algos.o recov.o tables.o int1.o int2.o int4.o \ · 4 unmodified lines
55
66 raid6_pq-$(CONFIG_X86) += recov_ssse3.o recov_avx2.o mmx.o sse1.o sse2.o avx2.o avx512.o recov_avx512.o
77 raid6_pq-$(CONFIG_ALTIVEC) += altivec1.o altivec2.o altivec4.o altivec8.o
8−raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o
8+raid6_pq-$(CONFIG_KERNEL_MODE_NEON) += neon.o neon1.o neon2.o neon4.o neon8.o recov_neon.o recov_neon_inner.o
99 raid6_pq-$(CONFIG_TILEGX) += tilegx8.o
1010 raid6_pq-$(CONFIG_S390) += s390vx8.o recov_s390xc.o
1111
@@ -26,7 +26,9 @@ NEON_FLAGS := -ffreestanding · 14 unmodified lines
2626 ifeq ($(ARCH),arm)
2727 NEON_FLAGS += -mfloat-abi=softfp -mfpu=neon
2828 endif
29+CFLAGS_recov_neon_inner.o += $(NEON_FLAGS)
2930 ifeq ($(ARCH),arm64)
31+CFLAGS_REMOVE_recov_neon_inner.o += -mgeneral-regs-only
3032 CFLAGS_REMOVE_neon1.o += -mgeneral-regs-only
3133 CFLAGS_REMOVE_neon2.o += -mgeneral-regs-only
3234 CFLAGS_REMOVE_neon4.o += -mgeneral-regs-only
lib/raid6/algos.c+3−0
@@ -112,6 +112,9 @@ const struct raid6_recov_calls *const raid6_recov_algos[] = { · 111 unmodified lines
112112 #endif
113113 #ifdef CONFIG_S390
114114 &raid6_recov_s390xc,
115+#endif
116+#if defined(CONFIG_KERNEL_MODE_NEON)
117+ &raid6_recov_neon,
115118 #endif
116119 &raid6_recov_intx1,
117120 NULL
lib/raid6/recov_neon.c+110−0
@@ -0,0 +1,110 @@
1+/*
2+ * Copyright (C) 2012 Intel Corporation
3+ * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
4+ *
5+ * This program is free software; you can redistribute it and/or
6+ * modify it under the terms of the GNU General Public License
7+ * as published by the Free Software Foundation; version 2
8+ * of the License.
9+ */
10+
11+#include <linux/raid/pq.h>
12+
13+#ifdef __KERNEL__
14+#include <asm/neon.h>
15+#else
16+#define kernel_neon_begin()
17+#define kernel_neon_end()
18+#define cpu_has_neon() (1)
19+#endif
20+
21+static int raid6_has_neon(void)
22+{
23+ return cpu_has_neon();
24+}
25+
26+void __raid6_2data_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dp,
27+ uint8_t *dq, const uint8_t *pbmul,
28+ const uint8_t *qmul);
29+
30+void __raid6_datap_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dq,
31+ const uint8_t *qmul);
32+
33+static void raid6_2data_recov_neon(int disks, size_t bytes, int faila,
34+ int failb, void **ptrs)
35+{
36+ u8 *p, *q, *dp, *dq;
37+ const u8 *pbmul; /* P multiplier table for B data */
38+ const u8 *qmul; /* Q multiplier table (for both) */
39+
40+ p = (u8 *)ptrs[disks - 2];
41+ q = (u8 *)ptrs[disks - 1];
42+
43+ /*
44+ * Compute syndrome with zero for the missing data pages
45+ * Use the dead data pages as temporary storage for
46+ * delta p and delta q
47+ */
48+ dp = (u8 *)ptrs[faila];
49+ ptrs[faila] = (void *)raid6_empty_zero_page;
50+ ptrs[disks - 2] = dp;
51+ dq = (u8 *)ptrs[failb];
52+ ptrs[failb] = (void *)raid6_empty_zero_page;
53+ ptrs[disks - 1] = dq;
54+
55+ raid6_call.gen_syndrome(disks, bytes, ptrs);
56+
57+ /* Restore pointer table */
58+ ptrs[faila] = dp;
59+ ptrs[failb] = dq;
60+ ptrs[disks - 2] = p;
61+ ptrs[disks - 1] = q;
62+
63+ /* Now, pick the proper data tables */
64+ pbmul = raid6_vgfmul[raid6_gfexi[failb-faila]];
65+ qmul = raid6_vgfmul[raid6_gfinv[raid6_gfexp[faila] ^
66+ raid6_gfexp[failb]]];
67+
68+ kernel_neon_begin();
69+ __raid6_2data_recov_neon(bytes, p, q, dp, dq, pbmul, qmul);
70+ kernel_neon_end();
71+}
72+
73+static void raid6_datap_recov_neon(int disks, size_t bytes, int faila,
74+ void **ptrs)
75+{
76+ u8 *p, *q, *dq;
77+ const u8 *qmul; /* Q multiplier table */
78+
79+ p = (u8 *)ptrs[disks - 2];
80+ q = (u8 *)ptrs[disks - 1];
81+
82+ /*
83+ * Compute syndrome with zero for the missing data page
84+ * Use the dead data page as temporary storage for delta q
85+ */
86+ dq = (u8 *)ptrs[faila];
87+ ptrs[faila] = (void *)raid6_empty_zero_page;
88+ ptrs[disks - 1] = dq;
89+
90+ raid6_call.gen_syndrome(disks, bytes, ptrs);
91+
92+ /* Restore pointer table */
93+ ptrs[faila] = dq;
94+ ptrs[disks - 1] = q;
95+
96+ /* Now, pick the proper data tables */
97+ qmul = raid6_vgfmul[raid6_gfinv[raid6_gfexp[faila]]];
98+
99+ kernel_neon_begin();
100+ __raid6_datap_recov_neon(bytes, p, q, dq, qmul);
101+ kernel_neon_end();
102+}
103+
104+const struct raid6_recov_calls raid6_recov_neon = {
105+ .data2 = raid6_2data_recov_neon,
106+ .datap = raid6_datap_recov_neon,
107+ .valid = raid6_has_neon,
108+ .name = "neon",
109+ .priority = 10,
110+};
lib/raid6/recov_neon_inner.c+117−0
@@ -0,0 +1,117 @@
1+/*
2+ * Copyright (C) 2012 Intel Corporation
3+ * Copyright (C) 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
4+ *
5+ * This program is free software; you can redistribute it and/or
6+ * modify it under the terms of the GNU General Public License
7+ * as published by the Free Software Foundation; version 2
8+ * of the License.
9+ */
10+
11+#include <arm_neon.h>
12+
13+static const uint8x16_t x0f = {
14+ 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f,
15+ 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f, 0x0f,
16+};
17+
18+#ifdef CONFIG_ARM
19+/*
20+ * AArch32 does not provide this intrinsic natively because it does not
21+ * implement the underlying instruction. AArch32 only provides a 64-bit
22+ * wide vtbl.8 instruction, so use that instead.
23+ */
24+static uint8x16_t vqtbl1q_u8(uint8x16_t a, uint8x16_t b)
25+{
26+ union {
27+ uint8x16_t val;
28+ uint8x8x2_t pair;
29+ } __a = { a };
30+
31+ return vcombine_u8(vtbl2_u8(__a.pair, vget_low_u8(b)),
32+ vtbl2_u8(__a.pair, vget_high_u8(b)));
33+}
34+#endif
35+
36+void __raid6_2data_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dp,
37+ uint8_t *dq, const uint8_t *pbmul,
38+ const uint8_t *qmul)
39+{
40+ uint8x16_t pm0 = vld1q_u8(pbmul);
41+ uint8x16_t pm1 = vld1q_u8(pbmul + 16);
42+ uint8x16_t qm0 = vld1q_u8(qmul);
43+ uint8x16_t qm1 = vld1q_u8(qmul + 16);
44+
45+ /*
46+ * while ( bytes-- ) {
47+ * uint8_t px, qx, db;
48+ *
49+ * px = *p ^ *dp;
50+ * qx = qmul[*q ^ *dq];
51+ * *dq++ = db = pbmul[px] ^ qx;
52+ * *dp++ = db ^ px;
53+ * p++; q++;
54+ * }
55+ */
56+
57+ while (bytes) {
58+ uint8x16_t vx, vy, px, qx, db;
59+
60+ px = veorq_u8(vld1q_u8(p), vld1q_u8(dp));
61+ vx = veorq_u8(vld1q_u8(q), vld1q_u8(dq));
62+
63+ vy = (uint8x16_t)vshrq_n_s16((int16x8_t)vx, 4);
64+ vx = vqtbl1q_u8(qm0, vandq_u8(vx, x0f));
65+ vy = vqtbl1q_u8(qm1, vandq_u8(vy, x0f));
66+ qx = veorq_u8(vx, vy);
67+
68+ vy = (uint8x16_t)vshrq_n_s16((int16x8_t)px, 4);
69+ vx = vqtbl1q_u8(pm0, vandq_u8(px, x0f));
70+ vy = vqtbl1q_u8(pm1, vandq_u8(vy, x0f));
71+ vx = veorq_u8(vx, vy);
72+ db = veorq_u8(vx, qx);
73+
74+ vst1q_u8(dq, db);
75+ vst1q_u8(dp, veorq_u8(db, px));
76+
77+ bytes -= 16;
78+ p += 16;
79+ q += 16;
80+ dp += 16;
81+ dq += 16;
82+ }
83+}
84+
85+void __raid6_datap_recov_neon(int bytes, uint8_t *p, uint8_t *q, uint8_t *dq,
86+ const uint8_t *qmul)
87+{
88+ uint8x16_t qm0 = vld1q_u8(qmul);
89+ uint8x16_t qm1 = vld1q_u8(qmul + 16);
90+
91+ /*
92+ * while (bytes--) {
93+ * *p++ ^= *dq = qmul[*q ^ *dq];
94+ * q++; dq++;
95+ * }
96+ */
97+
98+ while (bytes) {
99+ uint8x16_t vx, vy;
100+
101+ vx = veorq_u8(vld1q_u8(q), vld1q_u8(dq));
102+
103+ vy = (uint8x16_t)vshrq_n_s16((int16x8_t)vx, 4);
104+ vx = vqtbl1q_u8(qm0, vandq_u8(vx, x0f));
105+ vy = vqtbl1q_u8(qm1, vandq_u8(vy, x0f));
106+ vx = veorq_u8(vx, vy);
107+ vy = veorq_u8(vx, vld1q_u8(p));
108+
109+ vst1q_u8(dq, vx);
110+ vst1q_u8(p, vy);
111+
112+ bytes -= 16;
113+ p += 16;
114+ q += 16;
115+ dq += 16;
116+ }
117+}