linux/crypto/xor.c
<<
>>
Prefs
   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.  */
  24static struct xor_block_template *active_template;
  25
  26void
  27xor_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}
  52EXPORT_SYMBOL(xor_blocks);
  53
  54/* Set of all registered templates.  */
  55static struct xor_block_template *__initdata template_list;
  56
  57#ifndef MODULE
  58static void __init do_xor_register(struct xor_block_template *tmpl)
  59{
  60        tmpl->next = template_list;
  61        template_list = tmpl;
  62}
  63
  64static 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
  82static void __init
  83do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
  84{
  85        int speed;
  86        int i, j;
  87        ktime_t min, start, diff;
  88
  89        tmpl->next = template_list;
  90        template_list = tmpl;
  91
  92        preempt_disable();
  93
  94        min = (ktime_t)S64_MAX;
  95        for (i = 0; i < 3; i++) {
  96                start = ktime_get();
  97                for (j = 0; j < REPS; j++) {
  98                        mb(); /* prevent loop optimization */
  99                        tmpl->do_2(BENCH_SIZE, b1, b2);
 100                        mb();
 101                }
 102                diff = ktime_sub(ktime_get(), start);
 103                if (diff < min)
 104                        min = diff;
 105        }
 106
 107        preempt_enable();
 108
 109        // bytes/ns == GB/s, multiply by 1000 to get MB/s [not MiB/s]
 110        if (!min)
 111                min = 1;
 112        speed = (1000 * REPS * BENCH_SIZE) / (unsigned int)ktime_to_ns(min);
 113        tmpl->speed = speed;
 114
 115        pr_info("   %-16s: %5d MB/sec\n", tmpl->name, speed);
 116}
 117
 118static int __init
 119calibrate_xor_blocks(void)
 120{
 121        void *b1, *b2;
 122        struct xor_block_template *f, *fastest;
 123
 124        fastest = XOR_SELECT_TEMPLATE(NULL);
 125
 126        if (fastest) {
 127                printk(KERN_INFO "xor: automatically using best "
 128                                 "checksumming function   %-10s\n",
 129                       fastest->name);
 130                goto out;
 131        }
 132
 133        b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
 134        if (!b1) {
 135                printk(KERN_WARNING "xor: Yikes!  No memory available.\n");
 136                return -ENOMEM;
 137        }
 138        b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
 139
 140        /*
 141         * If this arch/cpu has a short-circuited selection, don't loop through
 142         * all the possible functions, just test the best one
 143         */
 144
 145#define xor_speed(templ)        do_xor_speed((templ), b1, b2)
 146
 147        printk(KERN_INFO "xor: measuring software checksum speed\n");
 148        template_list = NULL;
 149        XOR_TRY_TEMPLATES;
 150        fastest = template_list;
 151        for (f = fastest; f; f = f->next)
 152                if (f->speed > fastest->speed)
 153                        fastest = f;
 154
 155        pr_info("xor: using function: %s (%d MB/sec)\n",
 156               fastest->name, fastest->speed);
 157
 158#undef xor_speed
 159
 160        free_pages((unsigned long)b1, 2);
 161out:
 162        active_template = fastest;
 163        return 0;
 164}
 165
 166static __exit void xor_exit(void) { }
 167
 168MODULE_LICENSE("GPL");
 169
 170#ifndef MODULE
 171/* when built-in xor.o must initialize before drivers/md/md.o */
 172core_initcall(register_xor_blocks);
 173#endif
 174
 175module_init(calibrate_xor_blocks);
 176module_exit(xor_exit);
 177
lxr.linux.no kindly hosted by Redpill Linpro AS, provider of Linux consulting and operations services since 1995.