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 #include <asm/tlbflush.h>
  11
  12 /*
  13  * We rely on the nested NMI work to allow atomic faults from the NMI path; the
  14  * nested NMI paths are careful to preserve CR2.
  15  */
  16 unsigned long
  17 copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
  18 {
  19         unsigned long ret;
  20
  21         if (__range_not_ok(from, n, TASK_SIZE))
  22                 return n;
  23
  24         if (!nmi_uaccess_okay())
  25                 return n;
  26
  27         /*
  28          * Even though this function is typically called from NMI/IRQ context
  29          * disable pagefaults so that its behaviour is consistent even when
  30          * called form other contexts.
  31          */
  32         pagefault_disable();
  33         ret = __copy_from_user_inatomic(to, from, n);
  34         pagefault_enable();
  35
  36         return ret;
  37 }
  38 EXPORT_SYMBOL_GPL(copy_from_user_nmi);