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); 175