Linux kernel mirror (for testing)
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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* -*- linux-c -*- ------------------------------------------------------- *
3 *
4 * Copyright 2002 H. Peter Anvin - All Rights Reserved
5 *
6 * ----------------------------------------------------------------------- */
7
8/*
9 * raid6/algos.c
10 *
11 * Algorithm list and algorithm selection for RAID-6
12 */
13
14#include <linux/raid/pq.h>
15#ifndef __KERNEL__
16#include <sys/mman.h>
17#include <stdio.h>
18#else
19#include <linux/module.h>
20#include <linux/gfp.h>
21/* In .bss so it's zeroed */
22const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
23EXPORT_SYMBOL(raid6_empty_zero_page);
24#endif
25
26struct raid6_calls raid6_call;
27EXPORT_SYMBOL_GPL(raid6_call);
28
29const struct raid6_calls * const raid6_algos[] = {
30#if defined(__i386__) && !defined(__arch_um__)
31 &raid6_avx512x2,
32 &raid6_avx512x1,
33 &raid6_avx2x2,
34 &raid6_avx2x1,
35 &raid6_sse2x2,
36 &raid6_sse2x1,
37 &raid6_sse1x2,
38 &raid6_sse1x1,
39 &raid6_mmxx2,
40 &raid6_mmxx1,
41#endif
42#if defined(__x86_64__) && !defined(__arch_um__)
43 &raid6_avx512x4,
44 &raid6_avx512x2,
45 &raid6_avx512x1,
46 &raid6_avx2x4,
47 &raid6_avx2x2,
48 &raid6_avx2x1,
49 &raid6_sse2x4,
50 &raid6_sse2x2,
51 &raid6_sse2x1,
52#endif
53#ifdef CONFIG_ALTIVEC
54 &raid6_vpermxor8,
55 &raid6_vpermxor4,
56 &raid6_vpermxor2,
57 &raid6_vpermxor1,
58 &raid6_altivec8,
59 &raid6_altivec4,
60 &raid6_altivec2,
61 &raid6_altivec1,
62#endif
63#if defined(CONFIG_S390)
64 &raid6_s390vx8,
65#endif
66#ifdef CONFIG_KERNEL_MODE_NEON
67 &raid6_neonx8,
68 &raid6_neonx4,
69 &raid6_neonx2,
70 &raid6_neonx1,
71#endif
72#ifdef CONFIG_LOONGARCH
73#ifdef CONFIG_CPU_HAS_LASX
74 &raid6_lasx,
75#endif
76#ifdef CONFIG_CPU_HAS_LSX
77 &raid6_lsx,
78#endif
79#endif
80#ifdef CONFIG_RISCV_ISA_V
81 &raid6_rvvx1,
82 &raid6_rvvx2,
83 &raid6_rvvx4,
84 &raid6_rvvx8,
85#endif
86 &raid6_intx8,
87 &raid6_intx4,
88 &raid6_intx2,
89 &raid6_intx1,
90 NULL
91};
92
93void (*raid6_2data_recov)(int, size_t, int, int, void **);
94EXPORT_SYMBOL_GPL(raid6_2data_recov);
95
96void (*raid6_datap_recov)(int, size_t, int, void **);
97EXPORT_SYMBOL_GPL(raid6_datap_recov);
98
99const struct raid6_recov_calls *const raid6_recov_algos[] = {
100#ifdef CONFIG_X86
101 &raid6_recov_avx512,
102 &raid6_recov_avx2,
103 &raid6_recov_ssse3,
104#endif
105#ifdef CONFIG_S390
106 &raid6_recov_s390xc,
107#endif
108#if defined(CONFIG_KERNEL_MODE_NEON)
109 &raid6_recov_neon,
110#endif
111#ifdef CONFIG_LOONGARCH
112#ifdef CONFIG_CPU_HAS_LASX
113 &raid6_recov_lasx,
114#endif
115#ifdef CONFIG_CPU_HAS_LSX
116 &raid6_recov_lsx,
117#endif
118#endif
119#ifdef CONFIG_RISCV_ISA_V
120 &raid6_recov_rvv,
121#endif
122 &raid6_recov_intx1,
123 NULL
124};
125
126#ifdef __KERNEL__
127#define RAID6_TIME_JIFFIES_LG2 4
128#else
129/* Need more time to be stable in userspace */
130#define RAID6_TIME_JIFFIES_LG2 9
131#define time_before(x, y) ((x) < (y))
132#endif
133
134#define RAID6_TEST_DISKS 8
135#define RAID6_TEST_DISKS_ORDER 3
136
137static inline const struct raid6_recov_calls *raid6_choose_recov(void)
138{
139 const struct raid6_recov_calls *const *algo;
140 const struct raid6_recov_calls *best;
141
142 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
143 if (!best || (*algo)->priority > best->priority)
144 if (!(*algo)->valid || (*algo)->valid())
145 best = *algo;
146
147 if (best) {
148 raid6_2data_recov = best->data2;
149 raid6_datap_recov = best->datap;
150
151 pr_info("raid6: using %s recovery algorithm\n", best->name);
152 } else
153 pr_err("raid6: Yikes! No recovery algorithm found!\n");
154
155 return best;
156}
157
158static inline const struct raid6_calls *raid6_choose_gen(
159 void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
160{
161 unsigned long perf, bestgenperf, j0, j1;
162 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
163 const struct raid6_calls *const *algo;
164 const struct raid6_calls *best;
165
166 for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
167 if (!best || (*algo)->priority >= best->priority) {
168 if ((*algo)->valid && !(*algo)->valid())
169 continue;
170
171 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
172 best = *algo;
173 break;
174 }
175
176 perf = 0;
177
178 preempt_disable();
179 j0 = jiffies;
180 while ((j1 = jiffies) == j0)
181 cpu_relax();
182 while (time_before(jiffies,
183 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
184 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
185 perf++;
186 }
187 preempt_enable();
188
189 if (perf > bestgenperf) {
190 bestgenperf = perf;
191 best = *algo;
192 }
193 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
194 (perf * HZ * (disks-2)) >>
195 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
196 }
197 }
198
199 if (!best) {
200 pr_err("raid6: Yikes! No algorithm found!\n");
201 goto out;
202 }
203
204 raid6_call = *best;
205
206 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
207 pr_info("raid6: skipped pq benchmark and selected %s\n",
208 best->name);
209 goto out;
210 }
211
212 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
213 best->name,
214 (bestgenperf * HZ * (disks - 2)) >>
215 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
216
217 if (best->xor_syndrome) {
218 perf = 0;
219
220 preempt_disable();
221 j0 = jiffies;
222 while ((j1 = jiffies) == j0)
223 cpu_relax();
224 while (time_before(jiffies,
225 j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
226 best->xor_syndrome(disks, start, stop,
227 PAGE_SIZE, *dptrs);
228 perf++;
229 }
230 preempt_enable();
231
232 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
233 (perf * HZ * (disks - 2)) >>
234 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
235 }
236
237out:
238 return best;
239}
240
241
242/* Try to pick the best algorithm */
243/* This code uses the gfmul table as convenient data set to abuse */
244
245int __init raid6_select_algo(void)
246{
247 const int disks = RAID6_TEST_DISKS;
248
249 const struct raid6_calls *gen_best;
250 const struct raid6_recov_calls *rec_best;
251 char *disk_ptr, *p;
252 void *dptrs[RAID6_TEST_DISKS];
253 int i, cycle;
254
255 /* prepare the buffer and fill it circularly with gfmul table */
256 disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
257 if (!disk_ptr) {
258 pr_err("raid6: Yikes! No memory available.\n");
259 return -ENOMEM;
260 }
261
262 p = disk_ptr;
263 for (i = 0; i < disks; i++)
264 dptrs[i] = p + PAGE_SIZE * i;
265
266 cycle = ((disks - 2) * PAGE_SIZE) / 65536;
267 for (i = 0; i < cycle; i++) {
268 memcpy(p, raid6_gfmul, 65536);
269 p += 65536;
270 }
271
272 if ((disks - 2) * PAGE_SIZE % 65536)
273 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
274
275 /* select raid gen_syndrome function */
276 gen_best = raid6_choose_gen(&dptrs, disks);
277
278 /* select raid recover functions */
279 rec_best = raid6_choose_recov();
280
281 free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
282
283 return gen_best && rec_best ? 0 : -EINVAL;
284}
285
286static void raid6_exit(void)
287{
288 do { } while (0);
289}
290
291subsys_initcall(raid6_select_algo);
292module_exit(raid6_exit);
293MODULE_LICENSE("GPL");
294MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");