v4.19.13 snapshot.
diff --git a/arch/arm64/lib/clear_page.S b/arch/arm64/lib/clear_page.S
new file mode 100644
index 0000000..ef08e90
--- /dev/null
+++ b/arch/arm64/lib/clear_page.S
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2012 ARM Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/linkage.h>
+#include <linux/const.h>
+#include <asm/assembler.h>
+#include <asm/page.h>
+
+/*
+ * Clear page @dest
+ *
+ * Parameters:
+ * x0 - dest
+ */
+ENTRY(clear_page)
+ mrs x1, dczid_el0
+ and w1, w1, #0xf
+ mov x2, #4
+ lsl x1, x2, x1
+
+1: dc zva, x0
+ add x0, x0, x1
+ tst x0, #(PAGE_SIZE - 1)
+ b.ne 1b
+ ret
+ENDPROC(clear_page)