crypto/xor.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * xor.c : Multiple Devices driver for Linux
   4  *
   5  * Copyright (C) 1996, 1997, 1998, 1999, 2000,
   6  * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson.
   7  *
   8  * Dispatch optimized RAID-5 checksumming functions.
   9  */
  10
  11 #define BH_TRACE 0
  12 #include <linux/module.h>
  13 #include <linux/gfp.h>
  14 #include <linux/raid/xor.h>
  15 #include <linux/jiffies.h>
  16 #include <linux/preempt.h>
  17 #include <asm/xor.h>
  18
  19 #ifndef XOR_SELECT_TEMPLATE
  20 #define XOR_SELECT_TEMPLATE(x) (x)
  21 #endif
  22
  23 /* The xor routines to use.  */
  24 static struct xor_block_template *active_template;
  25
  26 void
  27 xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs)
  28 {
  29         unsigned long *p1, *p2, *p3, *p4;
  30
  31         p1 = (unsigned long *) srcs[0];
  32         if (src_count == 1) {
  33                 active_template->do_2(bytes, dest, p1);
  34                 return;
  35         }
  36
  37         p2 = (unsigned long *) srcs[1];
  38         if (src_count == 2) {
  39                 active_template->do_3(bytes, dest, p1, p2);
  40                 return;
  41         }
  42
  43         p3 = (unsigned long *) srcs[2];
  44         if (src_count == 3) {
  45                 active_template->do_4(bytes, dest, p1, p2, p3);
  46                 return;
  47         }
  48
  49         p4 = (unsigned long *) srcs[3];
  50         active_template->do_5(bytes, dest, p1, p2, p3, p4);
  51 }
  52 EXPORT_SYMBOL(xor_blocks);
  53
  54 /* Set of all registered templates.  */
  55 static struct xor_block_template *__initdata template_list;
  56
  57 #ifndef MODULE
  58 static void __init do_xor_register(struct xor_block_template *tmpl)
  59 {
  60         tmpl->next = template_list;
  61         template_list = tmpl;
  62 }
  63
  64 static int __init register_xor_blocks(void)
  65 {
  66         active_template = XOR_SELECT_TEMPLATE(NULL);
  67
  68         if (!active_template) {
  69 #define xor_speed       do_xor_register
  70                 // register all the templates and pick the first as the default
  71                 XOR_TRY_TEMPLATES;
  72 #undef xor_speed
  73                 active_template = template_list;
  74         }
  75         return 0;
  76 }
  77 #endif
  78
  79 #define BENCH_SIZE      4096
  80 #define REPS            800U
  81
  82 static void __init
  83 do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
  84 {
  85         int speed;
  86         unsigned long reps;
  87         ktime_t min, start, t0;
  88
  89         tmpl->next = template_list;
  90         template_list = tmpl;
  91
  92         preempt_disable();
  93
  94         reps = 0;
  95         t0 = ktime_get();
  96         /* delay start until time has advanced */
  97         while ((start = ktime_get()) == t0)
  98                 cpu_relax();
  99         do {
 100                 mb(); /* prevent loop optimization */
 101                 tmpl->do_2(BENCH_SIZE, b1, b2);
 102                 mb();
 103         } while (reps++ < REPS || (t0 = ktime_get()) == start);
 104         min = ktime_sub(t0, start);
 105
 106         preempt_enable();
 107
 108         // bytes/ns == GB/s, multiply by 1000 to get MB/s [not MiB/s]
 109         speed = (1000 * reps * BENCH_SIZE) / (unsigned int)ktime_to_ns(min);
 110         tmpl->speed = speed;
 111
 112         pr_info("   %-16s: %5d MB/sec\n", tmpl->name, speed);
 113 }
 114
 115 static int __init
 116 calibrate_xor_blocks(void)
 117 {
 118         void *b1, *b2;
 119         struct xor_block_template *f, *fastest;
 120
 121         fastest = XOR_SELECT_TEMPLATE(NULL);
 122
 123         if (fastest) {
 124                 printk(KERN_INFO "xor: automatically using best "
 125                                  "checksumming function   %-10s\n",
 126                        fastest->name);
 127                 goto out;
 128         }
 129
 130         b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
 131         if (!b1) {
 132                 printk(KERN_WARNING "xor: Yikes!  No memory available.\n");
 133                 return -ENOMEM;
 134         }
 135         b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
 136
 137         /*
 138          * If this arch/cpu has a short-circuited selection, don't loop through
 139          * all the possible functions, just test the best one
 140          */
 141
 142 #define xor_speed(templ)        do_xor_speed((templ), b1, b2)
 143
 144         printk(KERN_INFO "xor: measuring software checksum speed\n");
 145         template_list = NULL;
 146         XOR_TRY_TEMPLATES;
 147         fastest = template_list;
 148         for (f = fastest; f; f = f->next)
 149                 if (f->speed > fastest->speed)
 150                         fastest = f;
 151
 152         pr_info("xor: using function: %s (%d MB/sec)\n",
 153                fastest->name, fastest->speed);
 154
 155 #undef xor_speed
 156
 157         free_pages((unsigned long)b1, 2);
 158 out:
 159         active_template = fastest;
 160         return 0;
 161 }
 162
 163 static __exit void xor_exit(void) { }
 164
 165 MODULE_DESCRIPTION("RAID-5 checksumming functions");
 166 MODULE_LICENSE("GPL");
 167
 168 #ifndef MODULE
 169 /* when built-in xor.o must initialize before drivers/md/md.o */
 170 core_initcall(register_xor_blocks);
 171 #endif
 172
 173 module_init(calibrate_xor_blocks);
 174 module_exit(xor_exit);