1 files changed, 47 insertions, 0 deletions
diff --git a/arch/arm64/lib/strnlen_user.S b/arch/arm64/lib/strnlen_user.S
new file mode 100644
index 000000000000..7f7b176a5646
--- /dev/null
+++ b/arch/arm64/lib/strnlen_user.S
@@ -0,0 +1,47 @@
+/*
+ * Based on arch/arm/lib/strnlen_user.S
+ *
+ * Copyright (C) 1995-2000 Russell King
+ * 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 <asm/assembler.h>
+#include <asm/errno.h>
+
+	.text
+	.align	5
+
+/* Prototype: unsigned long __strnlen_user(const char *str, long n)
+ * Purpose  : get length of a string in user memory
+ * Params   : str - address of string in user memory
+ * Returns  : length of string *including terminator*
+ *	      or zero on exception, or n if too long
+ */
+ENTRY(__strnlen_user)
+	mov	x2, x0
+1:	subs	x1, x1, #1
+	b.mi	2f
+USER(9f, ldrb	w3, [x0], #1	)
+	cbnz	w3, 1b
+2:	sub	x0, x0, x2
+	ret
+ENDPROC(__strnlen_user)
+
+	.section .fixup,"ax"
+	.align	0
+9:	mov	x0, #0
+	ret
+	.previous