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#ifdef CONFIG_AS_AVX512
32 &raid6_avx512x2,
33 &raid6_avx512x1,
34#endif
35 &raid6_avx2x2,
36 &raid6_avx2x1,
37 &raid6_sse2x2,
38 &raid6_sse2x1,
39 &raid6_sse1x2,
40 &raid6_sse1x1,
41 &raid6_mmxx2,
42 &raid6_mmxx1,
43#endif
44#if defined(__x86_64__) && !defined(__arch_um__)
45#ifdef CONFIG_AS_AVX512
46 &raid6_avx512x4,
47 &raid6_avx512x2,
48 &raid6_avx512x1,
49#endif
50 &raid6_avx2x4,
51 &raid6_avx2x2,
52 &raid6_avx2x1,
53 &raid6_sse2x4,
54 &raid6_sse2x2,
55 &raid6_sse2x1,
56#endif
57#ifdef CONFIG_ALTIVEC
58 &raid6_vpermxor8,
59 &raid6_vpermxor4,
60 &raid6_vpermxor2,
61 &raid6_vpermxor1,
62 &raid6_altivec8,
63 &raid6_altivec4,
64 &raid6_altivec2,
65 &raid6_altivec1,
66#endif
67#if defined(CONFIG_S390)
68 &raid6_s390vx8,
69#endif
70#ifdef CONFIG_KERNEL_MODE_NEON
71 &raid6_neonx8,
72 &raid6_neonx4,
73 &raid6_neonx2,
74 &raid6_neonx1,
75#endif
76#ifdef CONFIG_LOONGARCH
77#ifdef CONFIG_CPU_HAS_LASX
78 &raid6_lasx,
79#endif
80#ifdef CONFIG_CPU_HAS_LSX
81 &raid6_lsx,
82#endif
83#endif
84#if defined(__ia64__)
85 &raid6_intx32,
86 &raid6_intx16,
87#endif
88 &raid6_intx8,
89 &raid6_intx4,
90 &raid6_intx2,
91 &raid6_intx1,
92 NULL
93};
94
95void (*raid6_2data_recov)(int, size_t, int, int, void **);
96EXPORT_SYMBOL_GPL(raid6_2data_recov);
97
98void (*raid6_datap_recov)(int, size_t, int, void **);
99EXPORT_SYMBOL_GPL(raid6_datap_recov);
100
101const struct raid6_recov_calls *const raid6_recov_algos[] = {
102#ifdef CONFIG_X86
103#ifdef CONFIG_AS_AVX512
104 &raid6_recov_avx512,
105#endif
106 &raid6_recov_avx2,
107 &raid6_recov_ssse3,
108#endif
109#ifdef CONFIG_S390
110 &raid6_recov_s390xc,
111#endif
112#if defined(CONFIG_KERNEL_MODE_NEON)
113 &raid6_recov_neon,
114#endif
115#ifdef CONFIG_LOONGARCH
116#ifdef CONFIG_CPU_HAS_LASX
117 &raid6_recov_lasx,
118#endif
119#ifdef CONFIG_CPU_HAS_LSX
120 &raid6_recov_lsx,
121#endif
122#endif
123 &raid6_recov_intx1,
124 NULL
125};
126
127#ifdef __KERNEL__
128#define RAID6_TIME_JIFFIES_LG2 4
129#else
130/* Need more time to be stable in userspace */
131#define RAID6_TIME_JIFFIES_LG2 9
132#define time_before(x, y) ((x) < (y))
133#endif
134
135#define RAID6_TEST_DISKS 8
136#define RAID6_TEST_DISKS_ORDER 3
137
138static inline const struct raid6_recov_calls *raid6_choose_recov(void)
139{
140 const struct raid6_recov_calls *const *algo;
141 const struct raid6_recov_calls *best;
142
143 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
144 if (!best || (*algo)->priority > best->priority)
145 if (!(*algo)->valid || (*algo)->valid())
146 best = *algo;
147
148 if (best) {
149 raid6_2data_recov = best->data2;
150 raid6_datap_recov = best->datap;
151
152 pr_info("raid6: using %s recovery algorithm\n", best->name);
153 } else
154 pr_err("raid6: Yikes! No recovery algorithm found!\n");
155
156 return best;
157}
158
159static inline const struct raid6_calls *raid6_choose_gen(
160 void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
161{
162 unsigned long perf, bestgenperf, j0, j1;
163 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
164 const struct raid6_calls *const *algo;
165 const struct raid6_calls *best;
166
167 for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
168 if (!best || (*algo)->priority >= best->priority) {
169 if ((*algo)->valid && !(*algo)->valid())
170 continue;
171
172 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
173 best = *algo;
174 break;
175 }
176
177 perf = 0;
178
179 preempt_disable();
180 j0 = jiffies;
181 while ((j1 = jiffies) == j0)
182 cpu_relax();
183 while (time_before(jiffies,
184 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
185 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
186 perf++;
187 }
188 preempt_enable();
189
190 if (perf > bestgenperf) {
191 bestgenperf = perf;
192 best = *algo;
193 }
194 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
195 (perf * HZ * (disks-2)) >>
196 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
197 }
198 }
199
200 if (!best) {
201 pr_err("raid6: Yikes! No algorithm found!\n");
202 goto out;
203 }
204
205 raid6_call = *best;
206
207 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
208 pr_info("raid6: skipped pq benchmark and selected %s\n",
209 best->name);
210 goto out;
211 }
212
213 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
214 best->name,
215 (bestgenperf * HZ * (disks - 2)) >>
216 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
217
218 if (best->xor_syndrome) {
219 perf = 0;
220
221 preempt_disable();
222 j0 = jiffies;
223 while ((j1 = jiffies) == j0)
224 cpu_relax();
225 while (time_before(jiffies,
226 j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
227 best->xor_syndrome(disks, start, stop,
228 PAGE_SIZE, *dptrs);
229 perf++;
230 }
231 preempt_enable();
232
233 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
234 (perf * HZ * (disks - 2)) >>
235 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
236 }
237
238out:
239 return best;
240}
241
242
243/* Try to pick the best algorithm */
244/* This code uses the gfmul table as convenient data set to abuse */
245
246int __init raid6_select_algo(void)
247{
248 const int disks = RAID6_TEST_DISKS;
249
250 const struct raid6_calls *gen_best;
251 const struct raid6_recov_calls *rec_best;
252 char *disk_ptr, *p;
253 void *dptrs[RAID6_TEST_DISKS];
254 int i, cycle;
255
256 /* prepare the buffer and fill it circularly with gfmul table */
257 disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
258 if (!disk_ptr) {
259 pr_err("raid6: Yikes! No memory available.\n");
260 return -ENOMEM;
261 }
262
263 p = disk_ptr;
264 for (i = 0; i < disks; i++)
265 dptrs[i] = p + PAGE_SIZE * i;
266
267 cycle = ((disks - 2) * PAGE_SIZE) / 65536;
268 for (i = 0; i < cycle; i++) {
269 memcpy(p, raid6_gfmul, 65536);
270 p += 65536;
271 }
272
273 if ((disks - 2) * PAGE_SIZE % 65536)
274 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
275
276 /* select raid gen_syndrome function */
277 gen_best = raid6_choose_gen(&dptrs, disks);
278
279 /* select raid recover functions */
280 rec_best = raid6_choose_recov();
281
282 free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
283
284 return gen_best && rec_best ? 0 : -EINVAL;
285}
286
287static void raid6_exit(void)
288{
289 do { } while (0);
290}
291
292subsys_initcall(raid6_select_algo);
293module_exit(raid6_exit);
294MODULE_LICENSE("GPL");
295MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");