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 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 } 117 118 static int __init 119 calibrate_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); 161 out: 162 active_template = fastest; 163 return 0; 164 } 165 166 static __exit void xor_exit(void) { } 167 168 MODULE_DESCRIPTION("RAID-5 checksumming functions"); 169 MODULE_LICENSE("GPL"); 170 171 #ifndef MODULE 172 /* when built-in xor.o must initialize before drivers/md/md.o */ 173 core_initcall(register_xor_blocks); 174 #endif 175 176 module_init(calibrate_xor_blocks); 177 module_exit(xor_exit); 178