arm64: uaccess: Add the uaccess_flushcache.c file

/*

 * Copyright (C) 2017 ARM Ltd.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

#include <linux/uaccess.h>

#include <asm/barrier.h>

#include <asm/cacheflush.h>

void memcpy_flushcache(void *dst, const void *src, size_t cnt)

{

	/*

	 * We assume this should not be called with @dst pointing to

	 * non-cacheable memory, such that we don't need an explicit

	 * barrier to order the cache maintenance against the memcpy.

	 */

	memcpy(dst, src, cnt);

	__clean_dcache_area_pop(dst, cnt);

}

EXPORT_SYMBOL_GPL(memcpy_flushcache);

void memcpy_page_flushcache(char *to, struct page *page, size_t offset,

			    size_t len)

{

	memcpy_flushcache(to, page_address(page) + offset, len);

}

unsigned long __copy_user_flushcache(void *to, const void __user *from,

				     unsigned long n)

{

	unsigned long rc = __arch_copy_from_user(to, from, n);

	/* See above */

	__clean_dcache_area_pop(to, n - rc);

	return rc;

}