arch/alpha/lib/copy_user.S

   1 /*
   2  * arch/alpha/lib/copy_user.S
   3  *
   4  * Copy to/from user space, handling exceptions as we go..  This
   5  * isn't exactly pretty.
   6  *
   7  * This is essentially the same as "memcpy()", but with a few twists.
   8  * Notably, we have to make sure that $0 is always up-to-date and
   9  * contains the right "bytes left to copy" value (and that it is updated
  10  * only _after_ a successful copy). There is also some rather minor
  11  * exception setup stuff..
  12  */
  13
  14 #include <asm/export.h>
  15
  16 /* Allow an exception for an insn; exit if we get one.  */
  17 #define EXI(x,y...)                     \
  18         99: x,##y;                      \
  19         .section __ex_table,"a";        \
  20         .long 99b - .;                  \
  21         lda $31, $exitin-99b($31);      \
  22         .previous
  23
  24 #define EXO(x,y...)                     \
  25         99: x,##y;                      \
  26         .section __ex_table,"a";        \
  27         .long 99b - .;                  \
  28         lda $31, $exitout-99b($31);     \
  29         .previous
  30
  31         .set noat
  32         .align 4
  33         .globl __copy_user
  34         .ent __copy_user
  35 __copy_user:
  36         .prologue 0
  37         and $18,$18,$0
  38         and $16,7,$3
  39         beq $0,$35
  40         beq $3,$36
  41         subq $3,8,$3
  42         .align 4
  43 $37:
  44         EXI( ldq_u $1,0($17) )
  45         EXO( ldq_u $2,0($16) )
  46         extbl $1,$17,$1
  47         mskbl $2,$16,$2
  48         insbl $1,$16,$1
  49         addq $3,1,$3
  50         bis $1,$2,$1
  51         EXO( stq_u $1,0($16) )
  52         subq $0,1,$0
  53         addq $16,1,$16
  54         addq $17,1,$17
  55         beq $0,$41
  56         bne $3,$37
  57 $36:
  58         and $17,7,$1
  59         bic $0,7,$4
  60         beq $1,$43
  61         beq $4,$48
  62         EXI( ldq_u $3,0($17) )
  63         .align 4
  64 $50:
  65         EXI( ldq_u $2,8($17) )
  66         subq $4,8,$4
  67         extql $3,$17,$3
  68         extqh $2,$17,$1
  69         bis $3,$1,$1
  70         EXO( stq $1,0($16) )
  71         addq $17,8,$17
  72         subq $0,8,$0
  73         addq $16,8,$16
  74         bis $2,$2,$3
  75         bne $4,$50
  76 $48:
  77         beq $0,$41
  78         .align 4
  79 $57:
  80         EXI( ldq_u $1,0($17) )
  81         EXO( ldq_u $2,0($16) )
  82         extbl $1,$17,$1
  83         mskbl $2,$16,$2
  84         insbl $1,$16,$1
  85         bis $1,$2,$1
  86         EXO( stq_u $1,0($16) )
  87         subq $0,1,$0
  88         addq $16,1,$16
  89         addq $17,1,$17
  90         bne $0,$57
  91         br $31,$41
  92         .align 4
  93 $43:
  94         beq $4,$65
  95         .align 4
  96 $66:
  97         EXI( ldq $1,0($17) )
  98         subq $4,8,$4
  99         EXO( stq $1,0($16) )
 100         addq $17,8,$17
 101         subq $0,8,$0
 102         addq $16,8,$16
 103         bne $4,$66
 104 $65:
 105         beq $0,$41
 106         EXI( ldq $2,0($17) )
 107         EXO( ldq $1,0($16) )
 108         mskql $2,$0,$2
 109         mskqh $1,$0,$1
 110         bis $2,$1,$2
 111         EXO( stq $2,0($16) )
 112         bis $31,$31,$0
 113 $41:
 114 $35:
 115 $exitin:
 116 $exitout:
 117         ret $31,($26),1
 118
 119         .end __copy_user
 120 EXPORT_SYMBOL(__copy_user)