lib/raid6/algos.c

   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 #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
  91 void (*raid6_2data_recov)(int, size_t, int, int, void **);
  92 EXPORT_SYMBOL_GPL(raid6_2data_recov);
  93
  94 void (*raid6_datap_recov)(int, size_t, int, void **);
  95 EXPORT_SYMBOL_GPL(raid6_datap_recov);
  96
  97 const 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
 134 static 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
 155 static 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
 234 out:
 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
 242 int __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
 283 static void raid6_exit(void)
 284 {
 285         do { } while (0);
 286 }
 287
 288 subsys_initcall(raid6_select_algo);
 289 module_exit(raid6_exit);
 290 MODULE_LICENSE("GPL");
 291 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");