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-rw-r--r--arch/arm/lib/clear_user.S52
1 files changed, 52 insertions, 0 deletions
diff --git a/arch/arm/lib/clear_user.S b/arch/arm/lib/clear_user.S
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+++ b/arch/arm/lib/clear_user.S
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+/*
+ * 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
+