LXR linux/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.  */
  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#define BENCH_SIZE (PAGE_SIZE)
  58
  59static void __init
  60do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2)
  61{
  62        int speed;
  63        unsigned long now, j;
  64        int i, count, max;
  65
  66        tmpl->next = template_list;
  67        template_list = tmpl;
  68
  69        preempt_disable();
  70
  71        /*
  72         * Count the number of XORs done during a whole jiffy, and use
  73         * this to calculate the speed of checksumming.  We use a 2-page
  74         * allocation to have guaranteed color L1-cache layout.
  75         */
  76        max = 0;
  77        for (i = 0; i < 5; i++) {
  78                j = jiffies;
  79                count = 0;
  80                while ((now = jiffies) == j)
  81                        cpu_relax();
  82                while (time_before(jiffies, now + 1)) {
  83                        mb(); /* prevent loop optimzation */
  84                        tmpl->do_2(BENCH_SIZE, b1, b2);
  85                        mb();
  86                        count++;
  87                        mb();
  88                }
  89                if (count > max)
  90                        max = count;
  91        }
  92
  93        preempt_enable();
  94
  95        speed = max * (HZ * BENCH_SIZE / 1024);
  96        tmpl->speed = speed;
  97
  98        printk(KERN_INFO "   %-10s: %5d.%03d MB/sec\n", tmpl->name,
  99               speed / 1000, speed % 1000);
 100}
 101
 102static int __init
 103calibrate_xor_blocks(void)
 104{
 105        void *b1, *b2;
 106        struct xor_block_template *f, *fastest;
 107
 108        fastest = XOR_SELECT_TEMPLATE(NULL);
 109
 110        if (fastest) {
 111                printk(KERN_INFO "xor: automatically using best "
 112                                 "checksumming function   %-10s\n",
 113                       fastest->name);
 114                goto out;
 115        }
 116
 117        b1 = (void *) __get_free_pages(GFP_KERNEL, 2);
 118        if (!b1) {
 119                printk(KERN_WARNING "xor: Yikes!  No memory available.\n");
 120                return -ENOMEM;
 121        }
 122        b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE;
 123
 124        /*
 125         * If this arch/cpu has a short-circuited selection, don't loop through
 126         * all the possible functions, just test the best one
 127         */
 128
 129#define xor_speed(templ)        do_xor_speed((templ), b1, b2)
 130
 131        printk(KERN_INFO "xor: measuring software checksum speed\n");
 132        XOR_TRY_TEMPLATES;
 133        fastest = template_list;
 134        for (f = fastest; f; f = f->next)
 135                if (f->speed > fastest->speed)
 136                        fastest = f;
 137
 138        printk(KERN_INFO "xor: using function: %s (%d.%03d MB/sec)\n",
 139               fastest->name, fastest->speed / 1000, fastest->speed % 1000);
 140
 141#undef xor_speed
 142
 143        free_pages((unsigned long)b1, 2);
 144out:
 145        active_template = fastest;
 146        return 0;
 147}
 148
 149static __exit void xor_exit(void) { }
 150
 151MODULE_LICENSE("GPL");
 152
 153/* when built-in xor.o must initialize before drivers/md/md.o */
 154core_initcall(calibrate_xor_blocks);
 155module_exit(xor_exit);
 156