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