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