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