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 */
22 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
23 EXPORT_SYMBOL(raid6_empty_zero_page);
24 #endif
25
26 struct raid6_calls raid6_call;
27 EXPORT_SYMBOL_GPL(raid6_call);
28
29 const 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 &raid6_intx8,
85 &raid6_intx4,
86 &raid6_intx2,
87 &raid6_intx1,
88 NULL
89 };
90
91 void (*raid6_2data_recov)(int, size_t, int, int, void **);
92 EXPORT_SYMBOL_GPL(raid6_2data_recov);
93
94 void (*raid6_datap_recov)(int, size_t, int, void **);
95 EXPORT_SYMBOL_GPL(raid6_datap_recov);
96
97 const struct raid6_recov_calls *const raid6_recov_algos[] = {
98 #ifdef CONFIG_X86
99 #ifdef CONFIG_AS_AVX512
100 &raid6_recov_avx512,
101 #endif
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 &raid6_recov_intx1,
120 NULL
121 };
122
123 #ifdef __KERNEL__
124 #define RAID6_TIME_JIFFIES_LG2 4
125 #else
126 /* Need more time to be stable in userspace */
127 #define RAID6_TIME_JIFFIES_LG2 9
128 #define time_before(x, y) ((x) < (y))
129 #endif
130
131 #define RAID6_TEST_DISKS 8
132 #define RAID6_TEST_DISKS_ORDER 3
133
raid6_choose_recov(void)134 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
135 {
136 const struct raid6_recov_calls *const *algo;
137 const struct raid6_recov_calls *best;
138
139 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
140 if (!best || (*algo)->priority > best->priority)
141 if (!(*algo)->valid || (*algo)->valid())
142 best = *algo;
143
144 if (best) {
145 raid6_2data_recov = best->data2;
146 raid6_datap_recov = best->datap;
147
148 pr_info("raid6: using %s recovery algorithm\n", best->name);
149 } else
150 pr_err("raid6: Yikes! No recovery algorithm found!\n");
151
152 return best;
153 }
154
raid6_choose_gen(void * (* const dptrs)[RAID6_TEST_DISKS],const int disks)155 static inline const struct raid6_calls *raid6_choose_gen(
156 void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
157 {
158 unsigned long perf, bestgenperf, j0, j1;
159 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
160 const struct raid6_calls *const *algo;
161 const struct raid6_calls *best;
162
163 for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
164 if (!best || (*algo)->priority >= best->priority) {
165 if ((*algo)->valid && !(*algo)->valid())
166 continue;
167
168 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
169 best = *algo;
170 break;
171 }
172
173 perf = 0;
174
175 preempt_disable();
176 j0 = jiffies;
177 while ((j1 = jiffies) == j0)
178 cpu_relax();
179 while (time_before(jiffies,
180 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
181 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
182 perf++;
183 }
184 preempt_enable();
185
186 if (perf > bestgenperf) {
187 bestgenperf = perf;
188 best = *algo;
189 }
190 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
191 (perf * HZ * (disks-2)) >>
192 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
193 }
194 }
195
196 if (!best) {
197 pr_err("raid6: Yikes! No algorithm found!\n");
198 goto out;
199 }
200
201 raid6_call = *best;
202
203 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
204 pr_info("raid6: skipped pq benchmark and selected %s\n",
205 best->name);
206 goto out;
207 }
208
209 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
210 best->name,
211 (bestgenperf * HZ * (disks - 2)) >>
212 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
213
214 if (best->xor_syndrome) {
215 perf = 0;
216
217 preempt_disable();
218 j0 = jiffies;
219 while ((j1 = jiffies) == j0)
220 cpu_relax();
221 while (time_before(jiffies,
222 j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
223 best->xor_syndrome(disks, start, stop,
224 PAGE_SIZE, *dptrs);
225 perf++;
226 }
227 preempt_enable();
228
229 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
230 (perf * HZ * (disks - 2)) >>
231 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
232 }
233
234 out:
235 return best;
236 }
237
238
239 /* Try to pick the best algorithm */
240 /* This code uses the gfmul table as convenient data set to abuse */
241
raid6_select_algo(void)242 int __init raid6_select_algo(void)
243 {
244 const int disks = RAID6_TEST_DISKS;
245
246 const struct raid6_calls *gen_best;
247 const struct raid6_recov_calls *rec_best;
248 char *disk_ptr, *p;
249 void *dptrs[RAID6_TEST_DISKS];
250 int i, cycle;
251
252 /* prepare the buffer and fill it circularly with gfmul table */
253 disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
254 if (!disk_ptr) {
255 pr_err("raid6: Yikes! No memory available.\n");
256 return -ENOMEM;
257 }
258
259 p = disk_ptr;
260 for (i = 0; i < disks; i++)
261 dptrs[i] = p + PAGE_SIZE * i;
262
263 cycle = ((disks - 2) * PAGE_SIZE) / 65536;
264 for (i = 0; i < cycle; i++) {
265 memcpy(p, raid6_gfmul, 65536);
266 p += 65536;
267 }
268
269 if ((disks - 2) * PAGE_SIZE % 65536)
270 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
271
272 /* select raid gen_syndrome function */
273 gen_best = raid6_choose_gen(&dptrs, disks);
274
275 /* select raid recover functions */
276 rec_best = raid6_choose_recov();
277
278 free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
279
280 return gen_best && rec_best ? 0 : -EINVAL;
281 }
282
raid6_exit(void)283 static void raid6_exit(void)
284 {
285 do { } while (0);
286 }
287
288 subsys_initcall(raid6_select_algo);
289 module_exit(raid6_exit);
290 MODULE_LICENSE("GPL");
291 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
292