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