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 #if !RAID6_USE_EMPTY_ZERO_PAGE
  22 /* In .bss so it's zeroed */
  23 const char raid6_empty_zero_page[PAGE_SIZE] __attribute__((aligned(256)));
  24 EXPORT_SYMBOL(raid6_empty_zero_page);
  25 #endif
  26 #endif
  27
  28 struct raid6_calls raid6_call;
  29 EXPORT_SYMBOL_GPL(raid6_call);
  30
  31 const struct raid6_calls * const raid6_algos[] = {
  32 #if defined(__i386__) && !defined(__arch_um__)
  33 #ifdef CONFIG_AS_AVX512
  34         &raid6_avx512x2,
  35         &raid6_avx512x1,
  36 #endif
  37 #ifdef CONFIG_AS_AVX2
  38         &raid6_avx2x2,
  39         &raid6_avx2x1,
  40 #endif
  41         &raid6_sse2x2,
  42         &raid6_sse2x1,
  43         &raid6_sse1x2,
  44         &raid6_sse1x1,
  45         &raid6_mmxx2,
  46         &raid6_mmxx1,
  47 #endif
  48 #if defined(__x86_64__) && !defined(__arch_um__)
  49 #ifdef CONFIG_AS_AVX512
  50         &raid6_avx512x4,
  51         &raid6_avx512x2,
  52         &raid6_avx512x1,
  53 #endif
  54 #ifdef CONFIG_AS_AVX2
  55         &raid6_avx2x4,
  56         &raid6_avx2x2,
  57         &raid6_avx2x1,
  58 #endif
  59         &raid6_sse2x4,
  60         &raid6_sse2x2,
  61         &raid6_sse2x1,
  62 #endif
  63 #ifdef CONFIG_ALTIVEC
  64         &raid6_vpermxor8,
  65         &raid6_vpermxor4,
  66         &raid6_vpermxor2,
  67         &raid6_vpermxor1,
  68         &raid6_altivec8,
  69         &raid6_altivec4,
  70         &raid6_altivec2,
  71         &raid6_altivec1,
  72 #endif
  73 #if defined(CONFIG_S390)
  74         &raid6_s390vx8,
  75 #endif
  76 #ifdef CONFIG_KERNEL_MODE_NEON
  77         &raid6_neonx8,
  78         &raid6_neonx4,
  79         &raid6_neonx2,
  80         &raid6_neonx1,
  81 #endif
  82 #if defined(__ia64__)
  83         &raid6_intx32,
  84         &raid6_intx16,
  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_AS_AVX512
 101         &raid6_recov_avx512,
 102 #endif
 103 #ifdef CONFIG_AS_AVX2
 104         &raid6_recov_avx2,
 105 #endif
 106 #ifdef CONFIG_AS_SSSE3
 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         &raid6_recov_intx1,
 116         NULL
 117 };
 118
 119 #ifdef __KERNEL__
 120 #define RAID6_TIME_JIFFIES_LG2  4
 121 #else
 122 /* Need more time to be stable in userspace */
 123 #define RAID6_TIME_JIFFIES_LG2  9
 124 #define time_before(x, y) ((x) < (y))
 125 #endif
 126
 127 #define RAID6_TEST_DISKS        8
 128 #define RAID6_TEST_DISKS_ORDER  3
 129
 130 static inline const struct raid6_recov_calls *raid6_choose_recov(void)
 131 {
 132         const struct raid6_recov_calls *const *algo;
 133         const struct raid6_recov_calls *best;
 134
 135         for (best = NULL, algo = raid6_recov_algos; *algo; algo++)
 136                 if (!best || (*algo)->priority > best->priority)
 137                         if (!(*algo)->valid || (*algo)->valid())
 138                                 best = *algo;
 139
 140         if (best) {
 141                 raid6_2data_recov = best->data2;
 142                 raid6_datap_recov = best->datap;
 143
 144                 pr_info("raid6: using %s recovery algorithm\n", best->name);
 145         } else
 146                 pr_err("raid6: Yikes! No recovery algorithm found!\n");
 147
 148         return best;
 149 }
 150
 151 static inline const struct raid6_calls *raid6_choose_gen(
 152         void *(*const dptrs)[RAID6_TEST_DISKS], const int disks)
 153 {
 154         unsigned long perf, bestgenperf, bestxorperf, j0, j1;
 155         int start = (disks>>1)-1, stop = disks-3;       /* work on the second half of the disks */
 156         const struct raid6_calls *const *algo;
 157         const struct raid6_calls *best;
 158
 159         for (bestgenperf = 0, bestxorperf = 0, best = NULL, algo = raid6_algos; *algo; algo++) {
 160                 if (!best || (*algo)->prefer >= best->prefer) {
 161                         if ((*algo)->valid && !(*algo)->valid())
 162                                 continue;
 163
 164                         if (!IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
 165                                 best = *algo;
 166                                 break;
 167                         }
 168
 169                         perf = 0;
 170
 171                         preempt_disable();
 172                         j0 = jiffies;
 173                         while ((j1 = jiffies) == j0)
 174                                 cpu_relax();
 175                         while (time_before(jiffies,
 176                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 177                                 (*algo)->gen_syndrome(disks, PAGE_SIZE, *dptrs);
 178                                 perf++;
 179                         }
 180                         preempt_enable();
 181
 182                         if (perf > bestgenperf) {
 183                                 bestgenperf = perf;
 184                                 best = *algo;
 185                         }
 186                         pr_info("raid6: %-8s gen() %5ld MB/s\n", (*algo)->name,
 187                                 (perf * HZ * (disks-2)) >>
 188                                 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2));
 189
 190                         if (!(*algo)->xor_syndrome)
 191                                 continue;
 192
 193                         perf = 0;
 194
 195                         preempt_disable();
 196                         j0 = jiffies;
 197                         while ((j1 = jiffies) == j0)
 198                                 cpu_relax();
 199                         while (time_before(jiffies,
 200                                             j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
 201                                 (*algo)->xor_syndrome(disks, start, stop,
 202                                                       PAGE_SIZE, *dptrs);
 203                                 perf++;
 204                         }
 205                         preempt_enable();
 206
 207                         if (best == *algo)
 208                                 bestxorperf = perf;
 209
 210                         pr_info("raid6: %-8s xor() %5ld MB/s\n", (*algo)->name,
 211                                 (perf * HZ * (disks-2)) >>
 212                                 (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
 213                 }
 214         }
 215
 216         if (best) {
 217                 if (IS_ENABLED(CONFIG_RAID6_PQ_BENCHMARK)) {
 218                         pr_info("raid6: using algorithm %s gen() %ld MB/s\n",
 219                                 best->name,
 220                                 (bestgenperf * HZ * (disks-2)) >>
 221                                 (20 - PAGE_SHIFT+RAID6_TIME_JIFFIES_LG2));
 222                         if (best->xor_syndrome)
 223                                 pr_info("raid6: .... xor() %ld MB/s, rmw enabled\n",
 224                                         (bestxorperf * HZ * (disks-2)) >>
 225                                         (20 - PAGE_SHIFT + RAID6_TIME_JIFFIES_LG2 + 1));
 226                 } else
 227                         pr_info("raid6: skip pq benchmark and using algorithm %s\n",
 228                                 best->name);
 229                 raid6_call = *best;
 230         } else
 231                 pr_err("raid6: Yikes!  No algorithm found!\n");
 232
 233         return best;
 234 }
 235
 236
 237 /* Try to pick the best algorithm */
 238 /* This code uses the gfmul table as convenient data set to abuse */
 239
 240 int __init raid6_select_algo(void)
 241 {
 242         const int disks = RAID6_TEST_DISKS;
 243
 244         const struct raid6_calls *gen_best;
 245         const struct raid6_recov_calls *rec_best;
 246         char *disk_ptr, *p;
 247         void *dptrs[RAID6_TEST_DISKS];
 248         int i, cycle;
 249
 250         /* prepare the buffer and fill it circularly with gfmul table */
 251         disk_ptr = (char *)__get_free_pages(GFP_KERNEL, RAID6_TEST_DISKS_ORDER);
 252         if (!disk_ptr) {
 253                 pr_err("raid6: Yikes!  No memory available.\n");
 254                 return -ENOMEM;
 255         }
 256
 257         p = disk_ptr;
 258         for (i = 0; i < disks; i++)
 259                 dptrs[i] = p + PAGE_SIZE * i;
 260
 261         cycle = ((disks - 2) * PAGE_SIZE) / 65536;
 262         for (i = 0; i < cycle; i++) {
 263                 memcpy(p, raid6_gfmul, 65536);
 264                 p += 65536;
 265         }
 266
 267         if ((disks - 2) * PAGE_SIZE % 65536)
 268                 memcpy(p, raid6_gfmul, (disks - 2) * PAGE_SIZE % 65536);
 269
 270         /* select raid gen_syndrome function */
 271         gen_best = raid6_choose_gen(&dptrs, disks);
 272
 273         /* select raid recover functions */
 274         rec_best = raid6_choose_recov();
 275
 276         free_pages((unsigned long)disk_ptr, RAID6_TEST_DISKS_ORDER);
 277
 278         return gen_best && rec_best ? 0 : -EINVAL;
 279 }
 280
 281 static void raid6_exit(void)
 282 {
 283         do { } while (0);
 284 }
 285
 286 subsys_initcall(raid6_select_algo);
 287 module_exit(raid6_exit);
 288 MODULE_LICENSE("GPL");
 289 MODULE_DESCRIPTION("RAID6 Q-syndrome calculations");