LXR linux/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 */
  16unsigned long
  17copy_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}
  38EXPORT_SYMBOL_GPL(copy_from_user_nmi);
  39