// SPDX-License-Identifier: GPL-2.0-only
#include <linux/printk.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/timekeeping.h>
#include <linux/string.h>

#ifdef CONFIG_X86
#include <asm/cacheflush.h>
#endif

#define NUM_PAGES	(1 << (MAX_ORDER + 5))
#define PG_SIZE		(PAGE_SIZE * NUM_PAGES)

static __init int memcpy_align_selftest(void)
{
	struct page *page1, *page2;
	char *dst, *src;
	ktime_t t0, t1;
	int err = 0;
	int i, j;

	page1 = alloc_contig_pages(NUM_PAGES, GFP_KERNEL, NUMA_NO_NODE, 0);
	if (!page1)
		return 1;

	page2 = alloc_contig_pages(NUM_PAGES, GFP_KERNEL, NUMA_NO_NODE, 0);
	if (!page2) {
		err = 1;
		goto free1;
	}

	printk("Strings selftest: memcpy testing with size: %lu Mb\n", PG_SIZE >> 20);

	src = page_to_virt(page1);
	dst = page_to_virt(page2);

	preempt_disable();

	for (i = 0; i < sizeof(void*); i++) {
#ifdef CONFIG_X86
		for (j = 0; j < PG_SIZE; j += L1_CACHE_BYTES) {
			clflush(src + j);
			clflush(dst + j);
			cond_resched();
		}
#endif
		for (j = 0; j < sizeof(void*); j++) {
			t0 = ktime_get();
			memcpy(dst + i, src + j, PG_SIZE - max(i, j));
			t1 = ktime_get();
			printk("Strings selftest: memcpy(dst+%d, src+%d), distance %lu: %llu Mb/s\n",
			       i, j, (j - i) % sizeof(long),
			       PG_SIZE * (1000000000l / 1048576l) / (t1-t0));
			cond_resched();
		}
		printk("\n");
	}

	preempt_enable();

	free_contig_range(page_to_pfn(page2), NUM_PAGES);

free1:
	free_contig_range(page_to_pfn(page1), NUM_PAGES);

	return err;
}