[ARM] 2946/2: split --arch_clear_user() out of lib/uaccess.S

Patch from Nicolas Pitre

Required for future enhancement patches.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 52 insertions, 0 deletions

diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S
new file mode 100644
index 0000000..7ff9f83
--- /dev/null
+++ b/arch/arm/lib/clear_user.S
@@ -0,0 +1,52 @@
+/*
+ *  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 __arch_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(__arch_clear_user)
+		stmfd	sp!, {r1, lr}
+		mov	r2, #0
+		cmp	r1, #4
+		blt	2f
+		ands	ip, r0, #3
+		beq	1f
+		cmp	ip, #2
+USER(		strbt	r2, [r0], #1)
+USER(		strlebt	r2, [r0], #1)
+USER(		strltbt	r2, [r0], #1)
+		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
+USER(		strplt	r2, [r0], #4)
+USER(		strplt	r2, [r0], #4)
+		bpl	1b
+		adds	r1, r1, #4		@  3  2  1  0 -1 -2 -3
+USER(		strplt	r2, [r0], #4)
+2:		tst	r1, #2			@ 1x 1x 0x 0x 1x 1x 0x
+USER(		strnebt	r2, [r0], #1)
+USER(		strnebt	r2, [r0], #1)
+		tst	r1, #1			@ x1 x0 x1 x0 x1 x0 x1
+USER(		strnebt	r2, [r0], #1)
+		mov	r0, #0
+		LOADREGS(fd,sp!, {r1, pc})
+
+		.section .fixup,"ax"
+		.align	0
+9001:		LOADREGS(fd,sp!, {r0, pc})
+		.previous
+