v4.19.13 snapshot.
diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S
new file mode 100644
index 0000000..e936352
--- /dev/null
+++ b/arch/arm/lib/clear_user.S
@@ -0,0 +1,58 @@
+/*
+ * linux/arch/arm/lib/clear_user.S
+ *
+ * Copyright (C) 1995, 1996,1997,1998 Russell King
+ *
+ * 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.
+ */
+#include <linux/linkage.h>
+#include <asm/assembler.h>
+#include <asm/unwind.h>
+
+ .text
+
+/* Prototype: unsigned long arm_clear_user(void *addr, size_t sz)
+ * Purpose : clear some user memory
+ * Params : addr - user memory address to clear
+ * : sz - number of bytes to clear
+ * Returns : number of bytes NOT cleared
+ */
+ENTRY(__clear_user_std)
+WEAK(arm_clear_user)
+UNWIND(.fnstart)
+UNWIND(.save {r1, lr})
+ stmfd sp!, {r1, lr}
+ mov r2, #0
+ cmp r1, #4
+ blt 2f
+ ands ip, r0, #3
+ beq 1f
+ cmp ip, #2
+ strusr r2, r0, 1
+ strusr r2, r0, 1, le
+ strusr r2, r0, 1, lt
+ rsb ip, ip, #4
+ sub r1, r1, ip @ 7 6 5 4 3 2 1
+1: subs r1, r1, #8 @ -1 -2 -3 -4 -5 -6 -7
+ strusr r2, r0, 4, pl, rept=2
+ bpl 1b
+ adds r1, r1, #4 @ 3 2 1 0 -1 -2 -3
+ strusr r2, r0, 4, pl
+2: tst r1, #2 @ 1x 1x 0x 0x 1x 1x 0x
+ strusr r2, r0, 1, ne, rept=2
+ tst r1, #1 @ x1 x0 x1 x0 x1 x0 x1
+ it ne @ explicit IT needed for the label
+USER( strnebt r2, [r0])
+ mov r0, #0
+ ldmfd sp!, {r1, pc}
+UNWIND(.fnend)
+ENDPROC(arm_clear_user)
+ENDPROC(__clear_user_std)
+
+ .pushsection .text.fixup,"ax"
+ .align 0
+9001: ldmfd sp!, {r0, pc}
+ .popsection
+