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 12 /* 13 * best effort, GUP based copy_from_user() that is NMI-safe 14 */ 15 unsigned long 16 copy_from_user_nmi(void *to, const void __user *from, unsigned long n) 17 { 18 unsigned long offset, addr = (unsigned long)from; 19 unsigned long size, len = 0; 20 struct page *page; 21 void *map; 22 int ret; 23 24 do { 25 ret = __get_user_pages_fast(addr, 1, 0, &page); 26 if (!ret) 27 break; 28 29 offset = addr & (PAGE_SIZE - 1); 30 size = min(PAGE_SIZE - offset, n - len); 31 32 map = kmap_atomic(page); 33 memcpy(to, map+offset, size); 34 kunmap_atomic(map); 35 put_page(page); 36 37 len += size; 38 to += size; 39 addr += size; 40 41 } while (len < n); 42 43 return len; 44 } 45 EXPORT_SYMBOL_GPL(copy_from_user_nmi); 46