1/*
 2 * User address space access functions.
 3 *
 4 *  For licencing details see kernel-base/COPYING
 5 */
 6
 7#include <linux/highmem.h>
 8#include <linux/module.h>
 9
10#include <asm/word-at-a-time.h>
11#include <linux/sched.h>
12
13/*
14 * best effort, GUP based copy_from_user() that is NMI-safe
15 */
16unsigned long
17copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
18{
19	unsigned long offset, addr = (unsigned long)from;
20	unsigned long size, len = 0;
21	struct page *page;
22	void *map;
23	int ret;
24
25	if (__range_not_ok(from, n, TASK_SIZE))
26		return len;
27
28	do {
29		ret = __get_user_pages_fast(addr, 1, 0, &page);
30		if (!ret)
31			break;
32
33		offset = addr & (PAGE_SIZE - 1);
34		size = min(PAGE_SIZE - offset, n - len);
35
36		map = kmap_atomic(page);
37		memcpy(to, map+offset, size);
38		kunmap_atomic(map);
39		put_page(page);
40
41		len  += size;
42		to   += size;
43		addr += size;
44
45	} while (len < n);
46
47	return len;
48}
49EXPORT_SYMBOL_GPL(copy_from_user_nmi);