// SPDX-License-Identifier: GPL-2.0-or-later /* * xor.c : Multiple Devices driver for Linux * * Copyright (C) 1996, 1997, 1998, 1999, 2000, * Ingo Molnar, Matti Aarnio, Jakub Jelinek, Richard Henderson. * * Dispatch optimized RAID-5 checksumming functions. */ #define BH_TRACE 0 #include <linux/module.h> #include <linux/gfp.h> #include <linux/raid/xor.h> #include <linux/jiffies.h> #include <linux/preempt.h> #include <asm/xor.h> #ifndef XOR_SELECT_TEMPLATE #define XOR_SELECT_TEMPLATE(x) (x) #endif /* The xor routines to use. */ static struct xor_block_template *active_template; void xor_blocks(unsigned int src_count, unsigned int bytes, void *dest, void **srcs) { unsigned long *p1, *p2, *p3, *p4; p1 = (unsigned long *) srcs[0]; if (src_count == 1) { active_template->do_2(bytes, dest, p1); return; } p2 = (unsigned long *) srcs[1]; if (src_count == 2) { active_template->do_3(bytes, dest, p1, p2); return; } p3 = (unsigned long *) srcs[2]; if (src_count == 3) { active_template->do_4(bytes, dest, p1, p2, p3); return; } p4 = (unsigned long *) srcs[3]; active_template->do_5(bytes, dest, p1, p2, p3, p4); } EXPORT_SYMBOL(xor_blocks); /* Set of all registered templates. */ static struct xor_block_template *__initdata template_list; #ifndef MODULE static void __init do_xor_register(struct xor_block_template *tmpl) { tmpl->next = template_list; template_list = tmpl; } static int __init register_xor_blocks(void) { active_template = XOR_SELECT_TEMPLATE(NULL); if (!active_template) { #define xor_speed do_xor_register // register all the templates and pick the first as the default XOR_TRY_TEMPLATES; #undef xor_speed active_template = template_list; } return 0; } #endif #define BENCH_SIZE 4096 #define REPS 800U static void __init do_xor_speed(struct xor_block_template *tmpl, void *b1, void *b2) { int speed; int i, j; ktime_t min, start, diff; tmpl->next = template_list; template_list = tmpl; preempt_disable(); min = (ktime_t)S64_MAX; for (i = 0; i < 3; i++) { start = ktime_get(); for (j = 0; j < REPS; j++) { mb(); /* prevent loop optimization */ tmpl->do_2(BENCH_SIZE, b1, b2); mb(); } diff = ktime_sub(ktime_get(), start); if (diff < min) min = diff; } preempt_enable(); // bytes/ns == GB/s, multiply by 1000 to get MB/s [not MiB/s] if (!min) min = 1; speed = (1000 * REPS * BENCH_SIZE) / (unsigned int)ktime_to_ns(min); tmpl->speed = speed; pr_info(" %-16s: %5d MB/sec\n", tmpl->name, speed); } static int __init calibrate_xor_blocks(void) { void *b1, *b2; struct xor_block_template *f, *fastest; fastest = XOR_SELECT_TEMPLATE(NULL); if (fastest) { printk(KERN_INFO "xor: automatically using best " "checksumming function %-10s\n", fastest->name); goto out; } b1 = (void *) __get_free_pages(GFP_KERNEL, 2); if (!b1) { printk(KERN_WARNING "xor: Yikes! No memory available.\n"); return -ENOMEM; } b2 = b1 + 2*PAGE_SIZE + BENCH_SIZE; /* * If this arch/cpu has a short-circuited selection, don't loop through * all the possible functions, just test the best one */ #define xor_speed(templ) do_xor_speed((templ), b1, b2) printk(KERN_INFO "xor: measuring software checksum speed\n"); template_list = NULL; XOR_TRY_TEMPLATES; fastest = template_list; for (f = fastest; f; f = f->next) if (f->speed > fastest->speed) fastest = f; pr_info("xor: using function: %s (%d MB/sec)\n", fastest->name, fastest->speed); #undef xor_speed free_pages((unsigned long)b1, 2); out: active_template = fastest; return 0; } static __exit void xor_exit(void) { } MODULE_LICENSE("GPL"); #ifndef MODULE /* when built-in xor.o must initialize before drivers/md/md.o */ core_initcall(register_xor_blocks); #endif module_init(calibrate_xor_blocks); module_exit(xor_exit);