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 #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
95 void (*raid6_2data_recov)(int, size_t, int, int, void **);
96 EXPORT_SYMBOL_GPL(raid6_2data_recov);
97
98 void (*raid6_datap_recov)(int, size_t, int, void **);
99 EXPORT_SYMBOL_GPL(raid6_datap_recov);
100
101 const 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
raid6_choose_recov(void)138 static 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
raid6_choose_gen(void * (* const dptrs)[RAID6_TEST_DISKS],const int disks)159 static 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
238 out:
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
raid6_select_algo(void)246 int __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
raid6_exit(void)287 static void raid6_exit(void)
288 {
289 do { } while (0);
290 }
291
292 subsys_initcall(raid6_select_algo);
293 module_exit(raid6_exit);
294 MODULE_LICENSE("GPL");
295 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
296