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 	&raid6_avx512x2,
32 	&raid6_avx512x1,
33 	&raid6_avx2x2,
34 	&raid6_avx2x1,
35 	&raid6_sse2x2,
36 	&raid6_sse2x1,
37 	&raid6_sse1x2,
38 	&raid6_sse1x1,
39 	&raid6_mmxx2,
40 	&raid6_mmxx1,
41 #endif
42 #if defined(__x86_64__) && !defined(__arch_um__)
43 	&raid6_avx512x4,
44 	&raid6_avx512x2,
45 	&raid6_avx512x1,
46 	&raid6_avx2x4,
47 	&raid6_avx2x2,
48 	&raid6_avx2x1,
49 	&raid6_sse2x4,
50 	&raid6_sse2x2,
51 	&raid6_sse2x1,
52 #endif
53 #ifdef CONFIG_ALTIVEC
54 	&raid6_vpermxor8,
55 	&raid6_vpermxor4,
56 	&raid6_vpermxor2,
57 	&raid6_vpermxor1,
58 	&raid6_altivec8,
59 	&raid6_altivec4,
60 	&raid6_altivec2,
61 	&raid6_altivec1,
62 #endif
63 #if defined(CONFIG_S390)
64 	&raid6_s390vx8,
65 #endif
66 #ifdef CONFIG_KERNEL_MODE_NEON
67 	&raid6_neonx8,
68 	&raid6_neonx4,
69 	&raid6_neonx2,
70 	&raid6_neonx1,
71 #endif
72 #ifdef CONFIG_LOONGARCH
73 #ifdef CONFIG_CPU_HAS_LASX
74 	&raid6_lasx,
75 #endif
76 #ifdef CONFIG_CPU_HAS_LSX
77 	&raid6_lsx,
78 #endif
79 #endif
80 #ifdef CONFIG_RISCV_ISA_V
81 	&raid6_rvvx1,
82 	&raid6_rvvx2,
83 	&raid6_rvvx4,
84 	&raid6_rvvx8,
85 #endif
86 	&raid6_intx8,
87 	&raid6_intx4,
88 	&raid6_intx2,
89 	&raid6_intx1,
90 	NULL
91 };
92 
93 void (*raid6_2data_recov)(int, size_t, int, int, void **);
94 EXPORT_SYMBOL_GPL(raid6_2data_recov);
95 
96 void (*raid6_datap_recov)(int, size_t, int, void **);
97 EXPORT_SYMBOL_GPL(raid6_datap_recov);
98 
99 const struct raid6_recov_calls *const raid6_recov_algos[] = {
100 #ifdef CONFIG_X86
101 	&raid6_recov_avx512,
102 	&raid6_recov_avx2,
103 	&raid6_recov_ssse3,
104 #endif
105 #ifdef CONFIG_S390
106 	&raid6_recov_s390xc,
107 #endif
108 #if defined(CONFIG_KERNEL_MODE_NEON)
109 	&raid6_recov_neon,
110 #endif
111 #ifdef CONFIG_LOONGARCH
112 #ifdef CONFIG_CPU_HAS_LASX
113 	&raid6_recov_lasx,
114 #endif
115 #ifdef CONFIG_CPU_HAS_LSX
116 	&raid6_recov_lsx,
117 #endif
118 #endif
119 #ifdef CONFIG_RISCV_ISA_V
120 	&raid6_recov_rvv,
121 #endif
122 	&raid6_recov_intx1,
123 	NULL
124 };
125 
126 #ifdef __KERNEL__
127 #define RAID6_TIME_JIFFIES_LG2	4
128 #else
129 /* Need more time to be stable in userspace */
130 #define RAID6_TIME_JIFFIES_LG2	9
131 #define time_before(x, y) ((x) < (y))
132 #endif
133 
134 #define RAID6_TEST_DISKS	8
135 #define RAID6_TEST_DISKS_ORDER	3
136 
137 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
138 {
139 	const struct raid6_recov_calls *const *algo;
140 	const struct raid6_recov_calls *best;
141 
142 	for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
143 		if (!best || (*algo)->priority > best->priority)
144 			if (!(*algo)->valid || (*algo)->valid())
145 				best = *algo;
146 
147 	if (best) {
148 		raid6_2data_recov = best->data2;
149 		raid6_datap_recov = best->datap;
150 
151 		pr_info("raid6: using %s recovery algorithm\n", best->name);
152 	} else
153 		pr_err("raid6: Yikes! No recovery algorithm found!\n");
154 
155 	return best;
156 }
157 
158 static inline const struct raid6_calls *raid6_choose_gen(
159 	void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
160 {
161 	unsigned long perf, bestgenperf, j0, j1;
162 	int start = (disks>>1)-1, stop = disks-3;	/* work on the second half of the disks */
163 	const struct raid6_calls *const *algo;
164 	const struct raid6_calls *best;
165 
166 	for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
167 		if (!best || (*algo)->priority >= best->priority) {
168 			if ((*algo)->valid && !(*algo)->valid())
169 				continue;
170 
171 			if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
172 				best = *algo;
173 				break;
174 			}
175 
176 			perf = 0;
177 
178 			preempt_disable();
179 			j0 = jiffies;
180 			while ((j1 = jiffies) == j0)
181 				cpu_relax();
182 			while (time_before(jiffies,
183 					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
184 				(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
185 				perf++;
186 			}
187 			preempt_enable();
188 
189 			if (perf > bestgenperf) {
190 				bestgenperf = perf;
191 				best = *algo;
192 			}
193 			pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
194 				(perf * HZ * (disks-2)) >>
195 				(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
196 		}
197 	}
198 
199 	if (!best) {
200 		pr_err("raid6: Yikes! No algorithm found!\n");
201 		goto out;
202 	}
203 
204 	raid6_call = *best;
205 
206 	if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
207 		pr_info("raid6: skipped pq benchmark and selected %s\n",
208 			best->name);
209 		goto out;
210 	}
211 
212 	pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
213 		best->name,
214 		(bestgenperf * HZ * (disks - 2)) >>
215 		(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
216 
217 	if (best->xor_syndrome) {
218 		perf = 0;
219 
220 		preempt_disable();
221 		j0 = jiffies;
222 		while ((j1 = jiffies) == j0)
223 			cpu_relax();
224 		while (time_before(jiffies,
225 				   j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
226 			best->xor_syndrome(disks, start, stop,
227 					   PAGE_SIZE, *dptrs);
228 			perf++;
229 		}
230 		preempt_enable();
231 
232 		pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
233 			(perf * HZ * (disks - 2)) >>
234 			(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
235 	}
236 
237 out:
238 	return best;
239 }
240 
241 
242 /* Try to pick the best algorithm */
243 /* This code uses the gfmul table as convenient data set to abuse */
244 
245 int __init raid6_select_algo(void)
246 {
247 	const int disks = RAID6_TEST_DISKS;
248 
249 	const struct raid6_calls *gen_best;
250 	const struct raid6_recov_calls *rec_best;
251 	char *disk_ptr, *p;
252 	void *dptrs[RAID6_TEST_DISKS];
253 	int i, cycle;
254 
255 	/* prepare the buffer and fill it circularly with gfmul table */
256 	disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
257 	if (!disk_ptr) {
258 		pr_err("raid6: Yikes!  No memory available.\n");
259 		return -ENOMEM;
260 	}
261 
262 	p = disk_ptr;
263 	for (i = 0; i < disks; i++)
264 		dptrs[i] = p + PAGE_SIZE * i;
265 
266 	cycle = ((disks - 2) * PAGE_SIZE) / 65536;
267 	for (i = 0; i < cycle; i++) {
268 		memcpy(p, raid6_gfmul, 65536);
269 		p += 65536;
270 	}
271 
272 	if ((disks - 2) * PAGE_SIZE % 65536)
273 		memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
274 
275 	/* select raid gen_syndrome function */
276 	gen_best = raid6_choose_gen(&dptrs, disks);
277 
278 	/* select raid recover functions */
279 	rec_best = raid6_choose_recov();
280 
281 	free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
282 
283 	return gen_best && rec_best ? 0 : -EINVAL;
284 }
285 
286 static void raid6_exit(void)
287 {
288 	do { } while (0);
289 }
290 
291 subsys_initcall(raid6_select_algo);
292 module_exit(raid6_exit);
293 MODULE_LICENSE("GPL");
294 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
295