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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/sh/lib/__clear_user.S
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/* SPDX-License-Identifier: GPL-2.0 */

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/*

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 * __clear_user_page, __clear_user, clear_page implementation of SuperH

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 *

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 * Copyright (C) 2001  Kaz Kojima

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 * Copyright (C) 2001, 2002  Niibe Yutaka

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 * Copyright (C) 2006  Paul Mundt

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 */

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#include <linux/linkage.h>

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#include <asm/page.h>

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ENTRY(__clear_user)

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	!

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	mov	#0, r0

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	mov	#0xffffffe0, r1

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	!

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	! r4..(r4+31)&~32 	   -------- not aligned	[ Area 0 ]

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	! (r4+31)&~32..(r4+r5)&~32 -------- aligned	[ Area 1 ]

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	! (r4+r5)&~32..r4+r5       -------- not aligned	[ Area 2 ]

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	!

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	! Clear area 0

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	mov	r4, r2

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	!

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	tst	r1, r5		! length < 32

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	bt	.Larea2		! skip to remainder

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	!

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	add	#31, r2

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	and	r1, r2

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	cmp/eq	r4, r2

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	bt	.Larea1

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	mov	r2, r3

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	sub	r4, r3

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	mov	r3, r7

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	mov	r4, r2

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	!

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.L0:	dt	r3

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0:	mov.b	r0, @r2

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	bf/s	.L0

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	 add	#1, r2

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	!

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	sub	r7, r5

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	mov	r2, r4

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.Larea1:

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	mov	r4, r3

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	add	r5, r3

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	and	r1, r3

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	cmp/hi	r2, r3

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	bf	.Larea2

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	!

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	! Clear area 1

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#if defined(CONFIG_CPU_SH4)

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1:	movca.l	r0, @r2

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#else

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1:	mov.l	r0, @r2

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#endif

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	add	#4, r2

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2:	mov.l	r0, @r2

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	add	#4, r2

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3:	mov.l	r0, @r2

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	add	#4, r2

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4:	mov.l	r0, @r2

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	add	#4, r2

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5:	mov.l	r0, @r2

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	add	#4, r2

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6:	mov.l	r0, @r2

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	add	#4, r2

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7:	mov.l	r0, @r2

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	add	#4, r2

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8:	mov.l	r0, @r2

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	add	#4, r2

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	cmp/hi	r2, r3

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	bt/s	1b

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	 nop

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	!

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	! Clear area 2

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.Larea2:

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	mov	r4, r3

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	add	r5, r3

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	cmp/hs	r3, r2

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	bt/s	.Ldone

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	 sub	r2, r3

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.L2:	dt	r3

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9:	mov.b	r0, @r2

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	bf/s	.L2

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	 add	#1, r2

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	!

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.Ldone:	rts

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	 mov	#0, r0	! return 0 as normal return

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	! return the number of bytes remained

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.Lbad_clear_user:

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	mov	r4, r0

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	add	r5, r0

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	rts

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	 sub	r2, r0

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.section __ex_table,"a"

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	.align 2

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	.long	0b, .Lbad_clear_user

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	.long	1b, .Lbad_clear_user

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	.long	2b, .Lbad_clear_user

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	.long	3b, .Lbad_clear_user

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	.long	4b, .Lbad_clear_user

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	.long	5b, .Lbad_clear_user

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	.long	6b, .Lbad_clear_user

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	.long	7b, .Lbad_clear_user

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	.long	8b, .Lbad_clear_user

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	.long	9b, .Lbad_clear_user

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.previous

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