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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/mips/lib/strncpy_user.S
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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, 1999 by Ralf Baechle

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 */

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#include <linux/errno.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	9b, handler;				\

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	.previous

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/*

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 * Returns: -EFAULT if exception before terminator, N if the entire

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 * buffer filled, else strlen.

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 */

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/*

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 * Ugly special case have to check: we might get passed a user space

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 * pointer which wraps into the kernel space.  We don't deal with that.  If

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 * it happens at most some bytes of the exceptions handlers will be copied.

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 */

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LEAF(__strncpy_from_user_asm)

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	LONG_L		v0, TI_ADDR_LIMIT($28)	# pointer ok?

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	and		v0, a1

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	bnez		v0, .Lfault

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FEXPORT(__strncpy_from_user_nocheck_asm)

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	move		v0, zero

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	move		v1, a1

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	.set		noreorder

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1:	EX(lbu, t0, (v1), .Lfault)

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	PTR_ADDIU	v1, 1

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	R10KCBARRIER(0(ra))

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	beqz		t0, 2f

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	 sb		t0, (a0)

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	PTR_ADDIU	v0, 1

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	.set		reorder

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	PTR_ADDIU	a0, 1

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	bne		v0, a2, 1b

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2:	PTR_ADDU	t0, a1, v0

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	xor		t0, a1

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	bltz		t0, .Lfault

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	jr		ra			# return n

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	END(__strncpy_from_user_asm)

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.Lfault:	li		v0, -EFAULT

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	jr		ra

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	.section	__ex_table,"a"

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	PTR		1b, .Lfault

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	.previous

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