From 849369d6c66d3054688672f97d31fceb8e8230fb Mon Sep 17 00:00:00 2001
From: root <root@artemis.panaceas.org>
Date: Fri, 25 Dec 2015 04:40:36 +0000
Subject: initial_commit

---
 arch/arm/lib/clear_user.S | 54 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 arch/arm/lib/clear_user.S

(limited to 'arch/arm/lib/clear_user.S')

diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S
new file mode 100644
index 00000000..14a0d988
--- /dev/null
+++ b/arch/arm/lib/clear_user.S
@@ -0,0 +1,54 @@
+/*
+ *  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>
+
+		.text
+
+/* Prototype: int __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(__clear_user)
+		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}
+ENDPROC(__clear_user)
+ENDPROC(__clear_user_std)
+
+		.pushsection .fixup,"ax"
+		.align	0
+9001:		ldmfd	sp!, {r0, pc}
+		.popsection
+
-- 
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