v4.19.13 snapshot.
diff --git a/arch/nds32/include/asm/mmu.h b/arch/nds32/include/asm/mmu.h
new file mode 100644
index 0000000..88b9ee8
--- /dev/null
+++ b/arch/nds32/include/asm/mmu.h
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef __NDS32_MMU_H
+#define __NDS32_MMU_H
+
+typedef struct {
+	unsigned int id;
+	void *vdso;
+} mm_context_t;
+
+#endif