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/highmem.h>
   8 #include <linux/module.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);