2 * User address space access functions.
4 * For licencing details see kernel-base/COPYING
7 #include <linux/uaccess.h>
8 #include <linux/export.h>
10 #include <asm/tlbflush.h>
13 * copy_from_user_nmi - NMI safe copy from user
14 * @to: Pointer to the destination buffer
15 * @from: Pointer to a user space address of the current task
16 * @n: Number of bytes to copy
18 * Returns: The number of not copied bytes. 0 is success, i.e. all bytes copied
20 * Contrary to other copy_from_user() variants this function can be called
21 * from NMI context. Despite the name it is not restricted to be called
22 * from NMI context. It is safe to be called from any other context as
23 * well. It disables pagefaults across the copy which means a fault will
26 * For NMI context invocations this relies on the nested NMI work to allow
27 * atomic faults from the NMI path; the nested NMI paths are careful to
31 copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
35 if (!__access_ok(from, n))
38 if (!nmi_uaccess_okay())
42 * Even though this function is typically called from NMI/IRQ context
43 * disable pagefaults so that its behaviour is consistent even when
44 * called from other contexts.
47 ret = __copy_from_user_inatomic(to, from, n);
52 EXPORT_SYMBOL_GPL(copy_from_user_nmi);