1 /* -*- linux-c -*- ------------------------------------------------------- *
2  *
3  *   Copyright 2002 H. Peter Anvin - All Rights Reserved
4  *
5  *   This program is free software; you can redistribute it and/or modify
6  *   it under the terms of the GNU General Public License as published by
7  *   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
8  *   Boston MA 02111-1307, USA; either version 2 of the License, or
9  *   (at your option) any later version; incorporated herein by reference.
10  *
11  * ----------------------------------------------------------------------- */
12 
13 /*
14  * raid6/algos.c
15  *
16  * Algorithm list and algorithm selection for RAID-6
17  */
18 
19 #include <linux/raid/pq.h>
20 #ifndef __KERNEL__
21 #include <sys/mman.h>
22 #include <stdio.h>
23 #else
24 #include <linux/module.h>
25 #include <linux/gfp.h>
26 #if !RAID6_USE_EMPTY_ZERO_PAGE
27 /* In .bss so it's zeroed */
28 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
29 EXPORT_SYMBOL(raid6_empty_zero_page);
30 #endif
31 #endif
32 
33 struct raid6_calls raid6_call;
34 EXPORT_SYMBOL_GPL(raid6_call);
35 
36 const struct raid6_calls * const raid6_algos[] = {
37 #if defined(__ia64__)
38 	&raid6_intx16,
39 	&raid6_intx32,
40 #endif
41 #if defined(__i386__) && !defined(__arch_um__)
42 	&raid6_mmxx1,
43 	&raid6_mmxx2,
44 	&raid6_sse1x1,
45 	&raid6_sse1x2,
46 	&raid6_sse2x1,
47 	&raid6_sse2x2,
48 #ifdef CONFIG_AS_AVX2
49 	&raid6_avx2x1,
50 	&raid6_avx2x2,
51 #endif
52 #ifdef CONFIG_AS_AVX512
53 	&raid6_avx512x1,
54 	&raid6_avx512x2,
55 #endif
56 #endif
57 #if defined(__x86_64__) && !defined(__arch_um__)
58 	&raid6_sse2x1,
59 	&raid6_sse2x2,
60 	&raid6_sse2x4,
61 #ifdef CONFIG_AS_AVX2
62 	&raid6_avx2x1,
63 	&raid6_avx2x2,
64 	&raid6_avx2x4,
65 #endif
66 #ifdef CONFIG_AS_AVX512
67 	&raid6_avx512x1,
68 	&raid6_avx512x2,
69 	&raid6_avx512x4,
70 #endif
71 #endif
72 #ifdef CONFIG_ALTIVEC
73 	&raid6_altivec1,
74 	&raid6_altivec2,
75 	&raid6_altivec4,
76 	&raid6_altivec8,
77 	&raid6_vpermxor1,
78 	&raid6_vpermxor2,
79 	&raid6_vpermxor4,
80 	&raid6_vpermxor8,
81 #endif
82 #if defined(CONFIG_S390)
83 	&raid6_s390vx8,
84 #endif
85 	&raid6_intx1,
86 	&raid6_intx2,
87 	&raid6_intx4,
88 	&raid6_intx8,
89 #ifdef CONFIG_KERNEL_MODE_NEON
90 	&raid6_neonx1,
91 	&raid6_neonx2,
92 	&raid6_neonx4,
93 	&raid6_neonx8,
94 #endif
95 	NULL
96 };
97 
98 void (*raid6_2data_recov)(int, size_t, int, int, void **);
99 EXPORT_SYMBOL_GPL(raid6_2data_recov);
100 
101 void (*raid6_datap_recov)(int, size_t, int, void **);
102 EXPORT_SYMBOL_GPL(raid6_datap_recov);
103 
104 const struct raid6_recov_calls *const raid6_recov_algos[] = {
105 #ifdef CONFIG_AS_AVX512
106 	&raid6_recov_avx512,
107 #endif
108 #ifdef CONFIG_AS_AVX2
109 	&raid6_recov_avx2,
110 #endif
111 #ifdef CONFIG_AS_SSSE3
112 	&raid6_recov_ssse3,
113 #endif
114 #ifdef CONFIG_S390
115 	&raid6_recov_s390xc,
116 #endif
117 #if defined(CONFIG_KERNEL_MODE_NEON)
118 	&raid6_recov_neon,
119 #endif
120 	&raid6_recov_intx1,
121 	NULL
122 };
123 
124 #ifdef __KERNEL__
125 #define RAID6_TIME_JIFFIES_LG2	4
126 #else
127 /* Need more time to be stable in userspace */
128 #define RAID6_TIME_JIFFIES_LG2	9
129 #define time_before(x, y) ((x) < (y))
130 #endif
131 
raid6_choose_recov(void)132 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
133 {
134 	const struct raid6_recov_calls *const *algo;
135 	const struct raid6_recov_calls *best;
136 
137 	for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
138 		if (!best || (*algo)->priority > best->priority)
139 			if (!(*algo)->valid || (*algo)->valid())
140 				best = *algo;
141 
142 	if (best) {
143 		raid6_2data_recov = best->data2;
144 		raid6_datap_recov = best->datap;
145 
146 		pr_info("raid6: using %s recovery algorithm\n", best->name);
147 	} else
148 		pr_err("raid6: Yikes! No recovery algorithm found!\n");
149 
150 	return best;
151 }
152 
raid6_choose_gen(void * (* const dptrs)[(65536/PAGE_SIZE)+2],const int disks)153 static inline const struct raid6_calls *raid6_choose_gen(
154 	void *(*const dptrs)[(65536/PAGE_SIZE)+2], const int disks)
155 {
156 	unsigned long perf, bestgenperf, bestxorperf, j0, j1;
157 	int start = (disks>>1)-1, stop = disks-3;	/* work on the second half of the disks */
158 	const struct raid6_calls *const *algo;
159 	const struct raid6_calls *best;
160 
161 	for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
162 		if (!best || (*algo)->prefer >= best->prefer) {
163 			if ((*algo)->valid && !(*algo)->valid())
164 				continue;
165 
166 			perf = 0;
167 
168 			preempt_disable();
169 			j0 = jiffies;
170 			while ((j1 = jiffies) == j0)
171 				cpu_relax();
172 			while (time_before(jiffies,
173 					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
174 				(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
175 				perf++;
176 			}
177 			preempt_enable();
178 
179 			if (perf > bestgenperf) {
180 				bestgenperf = perf;
181 				best = *algo;
182 			}
183 			pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
184 			       (perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
185 
186 			if (!(*algo)->xor_syndrome)
187 				continue;
188 
189 			perf = 0;
190 
191 			preempt_disable();
192 			j0 = jiffies;
193 			while ((j1 = jiffies) == j0)
194 				cpu_relax();
195 			while (time_before(jiffies,
196 					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
197 				(*algo)->xor_syndrome(disks, start, stop,
198 						      PAGE_SIZE, *dptrs);
199 				perf++;
200 			}
201 			preempt_enable();
202 
203 			if (best == *algo)
204 				bestxorperf = perf;
205 
206 			pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
207 				(perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
208 		}
209 	}
210 
211 	if (best) {
212 		pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
213 		       best->name,
214 		       (bestgenperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
215 		if (best->xor_syndrome)
216 			pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
217 			       (bestxorperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2+1));
218 		raid6_call = *best;
219 	} else
220 		pr_err("raid6: Yikes!  No algorithm found!\n");
221 
222 	return best;
223 }
224 
225 
226 /* Try to pick the best algorithm */
227 /* This code uses the gfmul table as convenient data set to abuse */
228 
raid6_select_algo(void)229 int __init raid6_select_algo(void)
230 {
231 	const int disks = (65536/PAGE_SIZE)+2;
232 
233 	const struct raid6_calls *gen_best;
234 	const struct raid6_recov_calls *rec_best;
235 	char *syndromes;
236 	void *dptrs[(65536/PAGE_SIZE)+2];
237 	int i;
238 
239 	for (i = 0; i < disks-2; i++)
240 		dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
241 
242 	/* Normal code - use a 2-page allocation to avoid D$ conflict */
243 	syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
244 
245 	if (!syndromes) {
246 		pr_err("raid6: Yikes!  No memory available.\n");
247 		return -ENOMEM;
248 	}
249 
250 	dptrs[disks-2] = syndromes;
251 	dptrs[disks-1] = syndromes + PAGE_SIZE;
252 
253 	/* select raid gen_syndrome function */
254 	gen_best = raid6_choose_gen(&dptrs, disks);
255 
256 	/* select raid recover functions */
257 	rec_best = raid6_choose_recov();
258 
259 	free_pages((unsigned long)syndromes, 1);
260 
261 	return gen_best && rec_best ? 0 : -EINVAL;
262 }
263 
raid6_exit(void)264 static void raid6_exit(void)
265 {
266 	do { } while (0);
267 }
268 
269 subsys_initcall(raid6_select_algo);
270 module_exit(raid6_exit);
271 MODULE_LICENSE("GPL");
272 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
273