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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/unicore32/lib/strncpy_from_user.S
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/*

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 * linux/arch/unicore32/lib/strncpy_from_user.S

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 *

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 * Code specific to PKUnity SoC and UniCore ISA

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 *

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 * Copyright (C) 2001-2010 GUAN Xue-tao

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 *

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 * This program is free software; you can redistribute it and/or modify

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 * it under the terms of the GNU General Public License version 2 as

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 * published by the Free Software Foundation.

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 */

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#include <linux/linkage.h>

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#include <asm/assembler.h>

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#include <asm/errno.h>

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	.text

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	.align	5

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/*

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 * Copy a string from user space to kernel space.

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 *  r0 = dst, r1 = src, r2 = byte length

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 * returns the number of characters copied (strlen of copied string),

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 *  -EFAULT on exception, or "len" if we fill the whole buffer

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 */

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ENTRY(__strncpy_from_user)

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	mov	ip, r1

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1:	sub.a	r2, r2, #1

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	ldrusr	r3, r1, 1, ns

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	bfs	2f

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	stb.w	r3, [r0]+, #1

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	cxor.a	r3, #0

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	bne	1b

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	sub	r1, r1, #1	@ take NUL character out of count

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2:	sub	r0, r1, ip

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	mov	pc, lr

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ENDPROC(__strncpy_from_user)

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	.pushsection .fixup,"ax"

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	.align	0

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9001:	mov	r3, #0

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	stb	r3, [r0+], #0	@ null terminate

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	mov	r0, #-EFAULT

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	mov	pc, lr

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	.popsection

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