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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/mips/lib/strnlen_user.S
26424 views
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/*

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 * This file is subject to the terms and conditions of the GNU General Public

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 * License.  See the file "COPYING" in the main directory of this archive

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 * for more details.

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 *

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 * Copyright (c) 1996, 1998, 1999, 2004 by Ralf Baechle

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 * Copyright (c) 1999 Silicon Graphics, Inc.

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 */

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#include <linux/export.h>

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#include <asm/asm.h>

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#include <asm/asm-offsets.h>

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#include <asm/regdef.h>

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#define EX(insn,reg,addr,handler)			\

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9:	insn	reg, addr;				\

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	.section __ex_table,"a";			\

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	PTR_WD	9b, handler;				\

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	.previous

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/*

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 * Return the size of a string including the ending NUL character up to a

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 * maximum of a1 or 0 in case of error.

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 *

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 * Note: for performance reasons we deliberately accept that a user may

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 *	 make strlen_user and strnlen_user access the first few KSEG0

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 *	 bytes.	 There's nothing secret there.	On 64-bit accessing beyond

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 *	 the maximum is a tad hairier ...

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 */

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LEAF(__strnlen_user_asm)

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	move		v0, a0

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	PTR_ADDU	a1, a0			# stop pointer

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1:

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#ifdef CONFIG_CPU_DADDI_WORKAROUNDS

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	.set		noat

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	li		AT, 1

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#endif

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	beq		v0, a1, 1f		# limit reached?

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#ifdef CONFIG_EVA

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	.set push

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	.set eva

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	EX(lbe, t0, (v0), .Lfault)

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	.set pop

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#else

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	EX(lb, t0, (v0), .Lfault)

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#endif

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	.set		noreorder

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	bnez		t0, 1b

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1:

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#ifndef CONFIG_CPU_DADDI_WORKAROUNDS

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	 PTR_ADDIU	v0, 1

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#else

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	 PTR_ADDU	v0, AT

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	.set		at

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#endif

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	.set		reorder

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	PTR_SUBU	v0, a0

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	jr		ra

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	END(__strnlen_user_asm)

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.Lfault:

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	move		v0, zero

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	jr		ra

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	EXPORT_SYMBOL(__strnlen_user_asm)

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