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/export.h> 9 10 #include <asm/word-at-a-time.h> 11 #include <linux/sched.h> 12 13 /* 14 * We rely on the nested NMI work to allow atomic faults from the NMI path; the 15 * nested NMI paths are careful to preserve CR2. 16 */ 17 unsigned long 18 copy_from_user_nmi(void *to, const void __user *from, unsigned long n) 19 { 20 unsigned long ret; 21 22 if (__range_not_ok(from, n, TASK_SIZE)) 23 return n; 24 25 /* 26 * Even though this function is typically called from NMI/IRQ context 27 * disable pagefaults so that its behaviour is consistent even when 28 * called form other contexts. 29 */ 30 pagefault_disable(); 31 ret = __copy_from_user_inatomic(to, from, n); 32 pagefault_enable(); 33 34 return ret; 35 } 36 EXPORT_SYMBOL_GPL(copy_from_user_nmi); 37 38 /** 39 * copy_to_user: - Copy a block of data into user space. 40 * @to: Destination address, in user space. 41 * @from: Source address, in kernel space. 42 * @n: Number of bytes to copy. 43 * 44 * Context: User context only. This function may sleep if pagefaults are 45 * enabled. 46 * 47 * Copy data from kernel space to user space. 48 * 49 * Returns number of bytes that could not be copied. 50 * On success, this will be zero. 51 */ 52 unsigned long _copy_to_user(void __user *to, const void *from, unsigned n) 53 { 54 if (access_ok(VERIFY_WRITE, to, n)) 55 n = __copy_to_user(to, from, n); 56 return n; 57 } 58 EXPORT_SYMBOL(_copy_to_user); 59 60 /** 61 * copy_from_user: - Copy a block of data from user space. 62 * @to: Destination address, in kernel space. 63 * @from: Source address, in user space. 64 * @n: Number of bytes to copy. 65 * 66 * Context: User context only. This function may sleep if pagefaults are 67 * enabled. 68 * 69 * Copy data from user space to kernel space. 70 * 71 * Returns number of bytes that could not be copied. 72 * On success, this will be zero. 73 * 74 * If some data could not be copied, this function will pad the copied 75 * data to the requested size using zero bytes. 76 */ 77 unsigned long _copy_from_user(void *to, const void __user *from, unsigned n) 78 { 79 if (access_ok(VERIFY_READ, from, n)) 80 n = __copy_from_user(to, from, n); 81 else 82 memset(to, 0, n); 83 return n; 84 } 85 EXPORT_SYMBOL(_copy_from_user); 86