1 files changed, 36 insertions, 0 deletions
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
new file mode 100644
index 00000000000..ddf9ecb53cc
--- /dev/null
+++ b/arch/x86/lib/usercopy.c
@@ -0,0 +1,36 @@
+/*
+ * User address space access functions.
+ *
+ *  For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/highmem.h>
+#include <linux/module.h>
+
+#include <asm/word-at-a-time.h>
+#include <linux/sched.h>
+
+/*
+ * We rely on the nested NMI work to allow atomic faults from the NMI path; the
+ * nested NMI paths are careful to preserve CR2.
+ */
+unsigned long
+copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
+{
+	unsigned long ret;
+
+	if (__range_not_ok(from, n, TASK_SIZE))
+		return 0;
+
+	/*
+	 * Even though this function is typically called from NMI/IRQ context
+	 * disable pagefaults so that its behaviour is consistent even when
+	 * called form other contexts.
+	 */
+	pagefault_disable();
+	ret = __copy_from_user_inatomic(to, from, n);
+	pagefault_enable();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(copy_from_user_nmi);