arch/x86/lib/usercopy.c

   1 /*
   2  * User address space access functions.
   3  *
   4  *  For licencing details see kernel-base/COPYING
   5  */
   6
   7 #include <linux/uaccess.h>
   8 #include <linux/export.h>
   9
  10 /*
  11  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
  12  * nested NMI paths are careful to preserve CR2.
  13  */
  14 unsigned long
  15 copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
  16 {
  17         unsigned long ret;
  18
  19         if (__range_not_ok(from, n, TASK_SIZE))
  20                 return n;
  21
  22         /*
  23          * Even though this function is typically called from NMI/IRQ context
  24          * disable pagefaults so that its behaviour is consistent even when
  25          * called form other contexts.
  26          */
  27         pagefault_disable();
  28         ret = __copy_from_user_inatomic(to, from, n);
  29         pagefault_enable();
  30
  31         return ret;
  32 }
  33 EXPORT_SYMBOL_GPL(copy_from_user_nmi);