1 /*
2 * Copyright 2017, Matt Brown, IBM Corp.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * vpermxor$#.c
10 *
11 * Based on H. Peter Anvin's paper - The mathematics of RAID-6
12 *
13 * $#-way unrolled portable integer math RAID-6 instruction set
14 * This file is postprocessed using unroll.awk
15 *
16 * vpermxor$#.c makes use of the vpermxor instruction to optimise the RAID6 Q
17 * syndrome calculations.
18 * This can be run on systems which have both Altivec and vpermxor instruction.
19 *
20 * This instruction was introduced in POWER8 - ISA v2.07.
21 */
22
23 #include <linux/raid/pq.h>
24 #ifdef CONFIG_ALTIVEC
25
26 #include <altivec.h>
27 #include <asm/ppc-opcode.h>
28 #ifdef __KERNEL__
29 #include <asm/cputable.h>
30 #include <asm/switch_to.h>
31 #endif
32
33 typedef vector unsigned char unative_t;
34 #define NSIZE sizeof(unative_t)
35
36 static const vector unsigned char gf_low = {0x1e, 0x1c, 0x1a, 0x18, 0x16, 0x14,
37 0x12, 0x10, 0x0e, 0x0c, 0x0a, 0x08,
38 0x06, 0x04, 0x02,0x00};
39 static const vector unsigned char gf_high = {0xfd, 0xdd, 0xbd, 0x9d, 0x7d, 0x5d,
40 0x3d, 0x1d, 0xe0, 0xc0, 0xa0, 0x80,
41 0x60, 0x40, 0x20, 0x00};
42
43 static void noinline raid6_vpermxor$#_gen_syndrome_real(int disks, size_t bytes,
44 void **ptrs)
45 {
46 u8 **dptr = (u8 **)ptrs;
47 u8 *p, *q;
48 int d, z, z0;
49 unative_t wp$$, wq$$, wd$$;
50
51 z0 = disks - 3; /* Highest data disk */
52 p = dptr[z0+1]; /* XOR parity */
53 q = dptr[z0+2]; /* RS syndrome */
54
55 for (d = 0; d < bytes; d += NSIZE*$#) {
56 wp$$ = wq$$ = *(unative_t *)&dptr[z0][d+$$*NSIZE];
57
58 for (z = z0-1; z>=0; z--) {
59 wd$$ = *(unative_t *)&dptr[z][d+$$*NSIZE];
60 /* P syndrome */
61 wp$$ = vec_xor(wp$$, wd$$);
62
63 /* Q syndrome */
64 asm(VPERMXOR(%0,%1,%2,%3):"=v"(wq$$):"v"(gf_high), "v"(gf_low), "v"(wq$$));
65 wq$$ = vec_xor(wq$$, wd$$);
66 }
67 *(unative_t *)&p[d+NSIZE*$$] = wp$$;
68 *(unative_t *)&q[d+NSIZE*$$] = wq$$;
69 }
70 }
71
72 static void raid6_vpermxor$#_gen_syndrome(int disks, size_t bytes, void **ptrs)
73 {
74 preempt_disable();
75 enable_kernel_altivec();
76
77 raid6_vpermxor$#_gen_syndrome_real(disks, bytes, ptrs);
78
79 disable_kernel_altivec();
80 preempt_enable();
81 }
82
83 int raid6_have_altivec_vpermxor(void);
84 #if $# == 1
85 int raid6_have_altivec_vpermxor(void)
86 {
87 /* Check if arch has both altivec and the vpermxor instructions */
88 # ifdef __KERNEL__
89 return (cpu_has_feature(CPU_FTR_ALTIVEC_COMP) &&
90 cpu_has_feature(CPU_FTR_ARCH_207S));
91 # else
92 return 1;
93 #endif
94
95 }
96 #endif
97
98 const struct raid6_calls raid6_vpermxor$# = {
99 raid6_vpermxor$#_gen_syndrome,
100 NULL,
101 raid6_have_altivec_vpermxor,
102 "vpermxor$#",
103 0
104 };
105 #endif
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.