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 #if !RAID6_USE_EMPTY_ZERO_PAGE
22 /* In .bss so it's zeroed */
23 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
24 EXPORT_SYMBOL(raid6_empty_zero_page);
25 #endif
26 #endif
27
28 struct raid6_calls raid6_call;
29 EXPORT_SYMBOL_GPL(raid6_call);
30
31 const struct raid6_calls * const raid6_algos[] = {
32 #if defined(__i386__) && !defined(__arch_um__)
33 #ifdef CONFIG_AS_AVX512
34 &raid6_avx512x2,
35 &raid6_avx512x1,
36 #endif
37 &raid6_avx2x2,
38 &raid6_avx2x1,
39 &raid6_sse2x2,
40 &raid6_sse2x1,
41 &raid6_sse1x2,
42 &raid6_sse1x1,
43 &raid6_mmxx2,
44 &raid6_mmxx1,
45 #endif
46 #if defined(__x86_64__) && !defined(__arch_um__)
47 #ifdef CONFIG_AS_AVX512
48 &raid6_avx512x4,
49 &raid6_avx512x2,
50 &raid6_avx512x1,
51 #endif
52 &raid6_avx2x4,
53 &raid6_avx2x2,
54 &raid6_avx2x1,
55 &raid6_sse2x4,
56 &raid6_sse2x2,
57 &raid6_sse2x1,
58 #endif
59 #ifdef CONFIG_ALTIVEC
60 &raid6_vpermxor8,
61 &raid6_vpermxor4,
62 &raid6_vpermxor2,
63 &raid6_vpermxor1,
64 &raid6_altivec8,
65 &raid6_altivec4,
66 &raid6_altivec2,
67 &raid6_altivec1,
68 #endif
69 #if defined(CONFIG_S390)
70 &raid6_s390vx8,
71 #endif
72 #ifdef CONFIG_KERNEL_MODE_NEON
73 &raid6_neonx8,
74 &raid6_neonx4,
75 &raid6_neonx2,
76 &raid6_neonx1,
77 #endif
78 #if defined(__ia64__)
79 &raid6_intx32,
80 &raid6_intx16,
81 #endif
82 &raid6_intx8,
83 &raid6_intx4,
84 &raid6_intx2,
85 &raid6_intx1,
86 NULL
87 };
88
89 void (*raid6_2data_recov)(int, size_t, int, int, void **);
90 EXPORT_SYMBOL_GPL(raid6_2data_recov);
91
92 void (*raid6_datap_recov)(int, size_t, int, void **);
93 EXPORT_SYMBOL_GPL(raid6_datap_recov);
94
95 const struct raid6_recov_calls *const raid6_recov_algos[] = {
96 #ifdef CONFIG_X86
97 #ifdef CONFIG_AS_AVX512
98 &raid6_recov_avx512,
99 #endif
100 &raid6_recov_avx2,
101 &raid6_recov_ssse3,
102 #endif
103 #ifdef CONFIG_S390
104 &raid6_recov_s390xc,
105 #endif
106 #if defined(CONFIG_KERNEL_MODE_NEON)
107 &raid6_recov_neon,
108 #endif
109 &raid6_recov_intx1,
110 NULL
111 };
112
113 #ifdef __KERNEL__
114 #define RAID6_TIME_JIFFIES_LG2 4
115 #else
116 /* Need more time to be stable in userspace */
117 #define RAID6_TIME_JIFFIES_LG2 9
118 #define time_before(x, y) ((x) < (y))
119 #endif
120
121 #define RAID6_TEST_DISKS 8
122 #define RAID6_TEST_DISKS_ORDER 3
123
raid6_choose_recov(void)124 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
125 {
126 const struct raid6_recov_calls *const *algo;
127 const struct raid6_recov_calls *best;
128
129 for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
130 if (!best || (*algo)->priority > best->priority)
131 if (!(*algo)->valid || (*algo)->valid())
132 best = *algo;
133
134 if (best) {
135 raid6_2data_recov = best->data2;
136 raid6_datap_recov = best->datap;
137
138 pr_info("raid6: using %s recovery algorithm\n", best->name);
139 } else
140 pr_err("raid6: Yikes! No recovery algorithm found!\n");
141
142 return best;
143 }
144
raid6_choose_gen(void * (* const dptrs)[RAID6_TEST_DISKS],const int disks)145 static inline const struct raid6_calls *raid6_choose_gen(
146 void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
147 {
148 unsigned long perf, bestgenperf, j0, j1;
149 int start = (disks>>1)-1, stop = disks-3; /* work on the second half of the disks */
150 const struct raid6_calls *const *algo;
151 const struct raid6_calls *best;
152
153 for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
154 if (!best || (*algo)->priority >= best->priority) {
155 if ((*algo)->valid && !(*algo)->valid())
156 continue;
157
158 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
159 best = *algo;
160 break;
161 }
162
163 perf = 0;
164
165 preempt_disable();
166 j0 = jiffies;
167 while ((j1 = jiffies) == j0)
168 cpu_relax();
169 while (time_before(jiffies,
170 j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
171 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
172 perf++;
173 }
174 preempt_enable();
175
176 if (perf > bestgenperf) {
177 bestgenperf = perf;
178 best = *algo;
179 }
180 pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
181 (perf * HZ * (disks-2)) >>
182 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
183 }
184 }
185
186 if (!best) {
187 pr_err("raid6: Yikes! No algorithm found!\n");
188 goto out;
189 }
190
191 raid6_call = *best;
192
193 if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
194 pr_info("raid6: skipped pq benchmark and selected %s\n",
195 best->name);
196 goto out;
197 }
198
199 pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
200 best->name,
201 (bestgenperf * HZ * (disks - 2)) >>
202 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
203
204 if (best->xor_syndrome) {
205 perf = 0;
206
207 preempt_disable();
208 j0 = jiffies;
209 while ((j1 = jiffies) == j0)
210 cpu_relax();
211 while (time_before(jiffies,
212 j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
213 best->xor_syndrome(disks, start, stop,
214 PAGE_SIZE, *dptrs);
215 perf++;
216 }
217 preempt_enable();
218
219 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
220 (perf * HZ * (disks - 2)) >>
221 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
222 }
223
224 out:
225 return best;
226 }
227
228
229 /* Try to pick the best algorithm */
230 /* This code uses the gfmul table as convenient data set to abuse */
231
raid6_select_algo(void)232 int __init raid6_select_algo(void)
233 {
234 const int disks = RAID6_TEST_DISKS;
235
236 const struct raid6_calls *gen_best;
237 const struct raid6_recov_calls *rec_best;
238 char *disk_ptr, *p;
239 void *dptrs[RAID6_TEST_DISKS];
240 int i, cycle;
241
242 /* prepare the buffer and fill it circularly with gfmul table */
243 disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
244 if (!disk_ptr) {
245 pr_err("raid6: Yikes! No memory available.\n");
246 return -ENOMEM;
247 }
248
249 p = disk_ptr;
250 for (i = 0; i < disks; i++)
251 dptrs[i] = p + PAGE_SIZE * i;
252
253 cycle = ((disks - 2) * PAGE_SIZE) / 65536;
254 for (i = 0; i < cycle; i++) {
255 memcpy(p, raid6_gfmul, 65536);
256 p += 65536;
257 }
258
259 if ((disks - 2) * PAGE_SIZE % 65536)
260 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
261
262 /* select raid gen_syndrome function */
263 gen_best = raid6_choose_gen(&dptrs, disks);
264
265 /* select raid recover functions */
266 rec_best = raid6_choose_recov();
267
268 free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
269
270 return gen_best && rec_best ? 0 : -EINVAL;
271 }
272
raid6_exit(void)273 static void raid6_exit(void)
274 {
275 do { } while (0);
276 }
277
278 subsys_initcall(raid6_select_algo);
279 module_exit(raid6_exit);
280 MODULE_LICENSE("GPL");
281 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
282