__clear_user.S
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/*
* __clear_user_page, __clear_user, clear_page implementation of SuperH
*
* Copyright (C) 2001 Kaz Kojima
* Copyright (C) 2001, 2002 Niibe Yutaka
* Copyright (C) 2006 Paul Mundt
*/
#include <linux/linkage.h>
#include <asm/page.h>
ENTRY(__clear_user)
!
mov #0, r0
mov #0xffffffe0, r1
!
! r4..(r4+31)&~32 -------- not aligned [ Area 0 ]
! (r4+31)&~32..(r4+r5)&~32 -------- aligned [ Area 1 ]
! (r4+r5)&~32..r4+r5 -------- not aligned [ Area 2 ]
!
! Clear area 0
mov r4, r2
!
tst r1, r5 ! length < 32
bt .Larea2 ! skip to remainder
!
add #31, r2
and r1, r2
cmp/eq r4, r2
bt .Larea1
mov r2, r3
sub r4, r3
mov r3, r7
mov r4, r2
!
.L0: dt r3
0: mov.b r0, @r2
bf/s .L0
add #1, r2
!
sub r7, r5
mov r2, r4
.Larea1:
mov r4, r3
add r5, r3
and r1, r3
cmp/hi r2, r3
bf .Larea2
!
! Clear area 1
#if defined(CONFIG_CPU_SH4)
1: movca.l r0, @r2
#else
1: mov.l r0, @r2
#endif
add #4, r2
2: mov.l r0, @r2
add #4, r2
3: mov.l r0, @r2
add #4, r2
4: mov.l r0, @r2
add #4, r2
5: mov.l r0, @r2
add #4, r2
6: mov.l r0, @r2
add #4, r2
7: mov.l r0, @r2
add #4, r2
8: mov.l r0, @r2
add #4, r2
cmp/hi r2, r3
bt/s 1b
nop
!
! Clear area 2
.Larea2:
mov r4, r3
add r5, r3
cmp/hs r3, r2
bt/s .Ldone
sub r2, r3
.L2: dt r3
9: mov.b r0, @r2
bf/s .L2
add #1, r2
!
.Ldone: rts
mov #0, r0 ! return 0 as normal return
! return the number of bytes remained
.Lbad_clear_user:
mov r4, r0
add r5, r0
rts
sub r2, r0
.section __ex_table,"a"
.align 2
.long 0b, .Lbad_clear_user
.long 1b, .Lbad_clear_user
.long 2b, .Lbad_clear_user
.long 3b, .Lbad_clear_user
.long 4b, .Lbad_clear_user
.long 5b, .Lbad_clear_user
.long 6b, .Lbad_clear_user
.long 7b, .Lbad_clear_user
.long 8b, .Lbad_clear_user
.long 9b, .Lbad_clear_user
.previous