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/arch/mips/lib/strnlen_user.S

https://bitbucket.org/evzijst/gittest
Assembly | 45 lines | 43 code | 2 blank | 0 comment | 2 complexity | 0e9b246a73f826554acce490e957c1ea MD5 | raw file
 1/*
 2 * This file is subject to the terms and conditions of the GNU General Public
 3 * License.  See the file "COPYING" in the main directory of this archive
 4 * for more details.
 5 *
 6 * Copyright (c) 1996, 1998, 1999, 2004 by Ralf Baechle
 7 * Copyright (c) 1999 Silicon Graphics, Inc.
 8 */
 9#include <asm/asm.h>
10#include <asm/offset.h>
11#include <asm/regdef.h>
12
13#define EX(insn,reg,addr,handler)			\
149:	insn	reg, addr;				\
15	.section __ex_table,"a";			\
16	PTR	9b, handler;				\
17	.previous
18
19/*
20 * Return the size of a string including the ending NUL character upto a
21 * maximum of a1 or 0 in case of error.
22 *
23 * Note: for performance reasons we deliberately accept that a user may
24 *       make strlen_user and strnlen_user access the first few KSEG0
25 *       bytes.  There's nothing secret there.  On 64-bit accessing beyond
26 *       the maximum is a tad hairier ...
27 */
28LEAF(__strnlen_user_asm)
29	LONG_L		v0, TI_ADDR_LIMIT($28)	# pointer ok?
30	and		v0, a0
31	bnez		v0, fault
32
33FEXPORT(__strnlen_user_nocheck_asm)
34	move		v0, a0
35	PTR_ADDU	a1, a0			# stop pointer
361:	beq		v0, a1, 1f		# limit reached?
37	EX(lb, t0, (v0), fault)
38	PTR_ADDU	v0, 1
39	bnez		t0, 1b
401:	PTR_SUBU	v0, a0
41	jr		ra
42	END(__strnlen_user_asm)
43
44fault:	move		v0, zero
45	jr		ra