arch/sh/lib/__clear_user.S

   1 /*
   2  * __clear_user_page, __clear_user, clear_page implementation of SuperH
   3  *
   4  * Copyright (C) 2001  Kaz Kojima
   5  * Copyright (C) 2001, 2002  Niibe Yutaka
   6  * Copyright (C) 2006  Paul Mundt
   7  */
   8 #include <linux/linkage.h>
   9 #include <asm/page.h>
  10
  11 ENTRY(__clear_user)
  12         !
  13         mov     #0, r0
  14         mov     #0xffffffe0, r1
  15         !
  16         ! r4..(r4+31)&~32          -------- not aligned [ Area 0 ]
  17         ! (r4+31)&~32..(r4+r5)&~32 -------- aligned     [ Area 1 ]
  18         ! (r4+r5)&~32..r4+r5       -------- not aligned [ Area 2 ]
  19         !
  20         ! Clear area 0
  21         mov     r4, r2
  22         !
  23         tst     r1, r5          ! length < 32
  24         bt      .Larea2         ! skip to remainder
  25         !
  26         add     #31, r2
  27         and     r1, r2
  28         cmp/eq  r4, r2
  29         bt      .Larea1
  30         mov     r2, r3
  31         sub     r4, r3
  32         mov     r3, r7
  33         mov     r4, r2
  34         !
  35 .L0:    dt      r3
  36 0:      mov.b   r0, @r2
  37         bf/s    .L0
  38          add    #1, r2
  39         !
  40         sub     r7, r5
  41         mov     r2, r4
  42 .Larea1:
  43         mov     r4, r3
  44         add     r5, r3
  45         and     r1, r3
  46         cmp/hi  r2, r3
  47         bf      .Larea2
  48         !
  49         ! Clear area 1
  50 #if defined(CONFIG_CPU_SH4)
  51 1:      movca.l r0, @r2
  52 #else
  53 1:      mov.l   r0, @r2
  54 #endif
  55         add     #4, r2
  56 2:      mov.l   r0, @r2
  57         add     #4, r2
  58 3:      mov.l   r0, @r2
  59         add     #4, r2
  60 4:      mov.l   r0, @r2
  61         add     #4, r2
  62 5:      mov.l   r0, @r2
  63         add     #4, r2
  64 6:      mov.l   r0, @r2
  65         add     #4, r2
  66 7:      mov.l   r0, @r2
  67         add     #4, r2
  68 8:      mov.l   r0, @r2
  69         add     #4, r2
  70         cmp/hi  r2, r3
  71         bt/s    1b
  72          nop
  73         !
  74         ! Clear area 2
  75 .Larea2:
  76         mov     r4, r3
  77         add     r5, r3
  78         cmp/hs  r3, r2
  79         bt/s    .Ldone
  80          sub    r2, r3
  81 .L2:    dt      r3
  82 9:      mov.b   r0, @r2
  83         bf/s    .L2
  84          add    #1, r2
  85         !
  86 .Ldone: rts
  87          mov    #0, r0  ! return 0 as normal return
  88
  89         ! return the number of bytes remained
  90 .Lbad_clear_user:
  91         mov     r4, r0
  92         add     r5, r0
  93         rts
  94          sub    r2, r0
  95
  96 .section __ex_table,"a"
  97         .align 2
  98         .long   0b, .Lbad_clear_user
  99         .long   1b, .Lbad_clear_user
 100         .long   2b, .Lbad_clear_user
 101         .long   3b, .Lbad_clear_user
 102         .long   4b, .Lbad_clear_user
 103         .long   5b, .Lbad_clear_user
 104         .long   6b, .Lbad_clear_user
 105         .long   7b, .Lbad_clear_user
 106         .long   8b, .Lbad_clear_user
 107         .long   9b, .Lbad_clear_user
 108 .previous