xref: /kernel/linux/linux-6.6/lib/raid6/algos.c (revision 62306a36) 
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 */
22const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
23EXPORT_SYMBOL(raid6_empty_zero_page);
24#endif
25
26struct raid6_calls raid6_call;
27EXPORT_SYMBOL_GPL(raid6_call);
28
29const 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#ifdef CONFIG_LOONGARCH
77#ifdef CONFIG_CPU_HAS_LASX
78	&raid6_lasx,
79#endif
80#ifdef CONFIG_CPU_HAS_LSX
81	&raid6_lsx,
82#endif
83#endif
84#if defined(__ia64__)
85	&raid6_intx32,
86	&raid6_intx16,
87#endif
88	&raid6_intx8,
89	&raid6_intx4,
90	&raid6_intx2,
91	&raid6_intx1,
92	NULL
93};
94
95void (*raid6_2data_recov)(int, size_t, int, int, void **);
96EXPORT_SYMBOL_GPL(raid6_2data_recov);
97
98void (*raid6_datap_recov)(int, size_t, int, void **);
99EXPORT_SYMBOL_GPL(raid6_datap_recov);
100
101const struct raid6_recov_calls *const raid6_recov_algos[] = {
102#ifdef CONFIG_X86
103#ifdef CONFIG_AS_AVX512
104	&raid6_recov_avx512,
105#endif
106	&raid6_recov_avx2,
107	&raid6_recov_ssse3,
108#endif
109#ifdef CONFIG_S390
110	&raid6_recov_s390xc,
111#endif
112#if defined(CONFIG_KERNEL_MODE_NEON)
113	&raid6_recov_neon,
114#endif
115#ifdef CONFIG_LOONGARCH
116#ifdef CONFIG_CPU_HAS_LASX
117	&raid6_recov_lasx,
118#endif
119#ifdef CONFIG_CPU_HAS_LSX
120	&raid6_recov_lsx,
121#endif
122#endif
123	&raid6_recov_intx1,
124	NULL
125};
126
127#ifdef __KERNEL__
128#define RAID6_TIME_JIFFIES_LG2	4
129#else
130/* Need more time to be stable in userspace */
131#define RAID6_TIME_JIFFIES_LG2	9
132#define time_before(x, y) ((x) < (y))
133#endif
134
135#define RAID6_TEST_DISKS	8
136#define RAID6_TEST_DISKS_ORDER	3
137
138static inline const struct raid6_recov_calls *raid6_choose_recov(void)
139{
140	const struct raid6_recov_calls *const *algo;
141	const struct raid6_recov_calls *best;
142
143	for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
144		if (!best || (*algo)->priority > best->priority)
145			if (!(*algo)->valid || (*algo)->valid())
146				best = *algo;
147
148	if (best) {
149		raid6_2data_recov = best->data2;
150		raid6_datap_recov = best->datap;
151
152		pr_info("raid6: using %s recovery algorithm\n", best->name);
153	} else
154		pr_err("raid6: Yikes! No recovery algorithm found!\n");
155
156	return best;
157}
158
159static inline const struct raid6_calls *raid6_choose_gen(
160	void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
161{
162	unsigned long perf, bestgenperf, j0, j1;
163	int start = (disks>>1)-1, stop = disks-3;	/* work on the second half of the disks */
164	const struct raid6_calls *const *algo;
165	const struct raid6_calls *best;
166
167	for (bestgenperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
168		if (!best || (*algo)->priority >= best->priority) {
169			if ((*algo)->valid && !(*algo)->valid())
170				continue;
171
172			if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
173				best = *algo;
174				break;
175			}
176
177			perf = 0;
178
179			preempt_disable();
180			j0 = jiffies;
181			while ((j1 = jiffies) == j0)
182				cpu_relax();
183			while (time_before(jiffies,
184					    j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
185				(*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
186				perf++;
187			}
188			preempt_enable();
189
190			if (perf > bestgenperf) {
191				bestgenperf = perf;
192				best = *algo;
193			}
194			pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
195				(perf * HZ * (disks-2)) >>
196				(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
197		}
198	}
199
200	if (!best) {
201		pr_err("raid6: Yikes! No algorithm found!\n");
202		goto out;
203	}
204
205	raid6_call = *best;
206
207	if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
208		pr_info("raid6: skipped pq benchmark and selected %s\n",
209			best->name);
210		goto out;
211	}
212
213	pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
214		best->name,
215		(bestgenperf * HZ * (disks - 2)) >>
216		(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
217
218	if (best->xor_syndrome) {
219		perf = 0;
220
221		preempt_disable();
222		j0 = jiffies;
223		while ((j1 = jiffies) == j0)
224			cpu_relax();
225		while (time_before(jiffies,
226				   j1 + (1 << RAID6_TIME_JIFFIES_LG2))) {
227			best->xor_syndrome(disks, start, stop,
228					   PAGE_SIZE, *dptrs);
229			perf++;
230		}
231		preempt_enable();
232
233		pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
234			(perf * HZ * (disks - 2)) >>
235			(20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
236	}
237
238out:
239	return best;
240}
241
242
243/* Try to pick the best algorithm */
244/* This code uses the gfmul table as convenient data set to abuse */
245
246int __init raid6_select_algo(void)
247{
248	const int disks = RAID6_TEST_DISKS;
249
250	const struct raid6_calls *gen_best;
251	const struct raid6_recov_calls *rec_best;
252	char *disk_ptr, *p;
253	void *dptrs[RAID6_TEST_DISKS];
254	int i, cycle;
255
256	/* prepare the buffer and fill it circularly with gfmul table */
257	disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
258	if (!disk_ptr) {
259		pr_err("raid6: Yikes!  No memory available.\n");
260		return -ENOMEM;
261	}
262
263	p = disk_ptr;
264	for (i = 0; i < disks; i++)
265		dptrs[i] = p + PAGE_SIZE * i;
266
267	cycle = ((disks - 2) * PAGE_SIZE) / 65536;
268	for (i = 0; i < cycle; i++) {
269		memcpy(p, raid6_gfmul, 65536);
270		p += 65536;
271	}
272
273	if ((disks - 2) * PAGE_SIZE % 65536)
274		memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
275
276	/* select raid gen_syndrome function */
277	gen_best = raid6_choose_gen(&dptrs, disks);
278
279	/* select raid recover functions */
280	rec_best = raid6_choose_recov();
281
282	free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
283
284	return gen_best && rec_best ? 0 : -EINVAL;
285}
286
287static void raid6_exit(void)
288{
289	do { } while (0);
290}
291
292subsys_initcall(raid6_select_algo);
293module_exit(raid6_exit);
294MODULE_LICENSE("GPL");
295MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");
296