root/arch/alpha/lib/copy_user.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * arch/alpha/lib/copy_user.S
   4  *
   5  * Copy to/from user space, handling exceptions as we go..  This
   6  * isn't exactly pretty.
   7  *
   8  * This is essentially the same as "memcpy()", but with a few twists.
   9  * Notably, we have to make sure that $0 is always up-to-date and
  10  * contains the right "bytes left to copy" value (and that it is updated
  11  * only _after_ a successful copy). There is also some rather minor
  12  * exception setup stuff..
  13  */
  14 
  15 #include <asm/export.h>
  16 
  17 /* Allow an exception for an insn; exit if we get one.  */
  18 #define EXI(x,y...)                     \
  19         99: x,##y;                      \
  20         .section __ex_table,"a";        \
  21         .long 99b - .;                  \
  22         lda $31, $exitin-99b($31);      \
  23         .previous
  24 
  25 #define EXO(x,y...)                     \
  26         99: x,##y;                      \
  27         .section __ex_table,"a";        \
  28         .long 99b - .;                  \
  29         lda $31, $exitout-99b($31);     \
  30         .previous
  31 
  32         .set noat
  33         .align 4
  34         .globl __copy_user
  35         .ent __copy_user
  36 __copy_user:
  37         .prologue 0
  38         mov $18,$0
  39         and $16,7,$3
  40         beq $0,$35
  41         beq $3,$36
  42         subq $3,8,$3
  43         .align 4
  44 $37:
  45         EXI( ldq_u $1,0($17) )
  46         EXO( ldq_u $2,0($16) )
  47         extbl $1,$17,$1
  48         mskbl $2,$16,$2
  49         insbl $1,$16,$1
  50         addq $3,1,$3
  51         bis $1,$2,$1
  52         EXO( stq_u $1,0($16) )
  53         subq $0,1,$0
  54         addq $16,1,$16
  55         addq $17,1,$17
  56         beq $0,$41
  57         bne $3,$37
  58 $36:
  59         and $17,7,$1
  60         bic $0,7,$4
  61         beq $1,$43
  62         beq $4,$48
  63         EXI( ldq_u $3,0($17) )
  64         .align 4
  65 $50:
  66         EXI( ldq_u $2,8($17) )
  67         subq $4,8,$4
  68         extql $3,$17,$3
  69         extqh $2,$17,$1
  70         bis $3,$1,$1
  71         EXO( stq $1,0($16) )
  72         addq $17,8,$17
  73         subq $0,8,$0
  74         addq $16,8,$16
  75         bis $2,$2,$3
  76         bne $4,$50
  77 $48:
  78         beq $0,$41
  79         .align 4
  80 $57:
  81         EXI( ldq_u $1,0($17) )
  82         EXO( ldq_u $2,0($16) )
  83         extbl $1,$17,$1
  84         mskbl $2,$16,$2
  85         insbl $1,$16,$1
  86         bis $1,$2,$1
  87         EXO( stq_u $1,0($16) )
  88         subq $0,1,$0
  89         addq $16,1,$16
  90         addq $17,1,$17
  91         bne $0,$57
  92         br $31,$41
  93         .align 4
  94 $43:
  95         beq $4,$65
  96         .align 4
  97 $66:
  98         EXI( ldq $1,0($17) )
  99         subq $4,8,$4
 100         EXO( stq $1,0($16) )
 101         addq $17,8,$17
 102         subq $0,8,$0
 103         addq $16,8,$16
 104         bne $4,$66
 105 $65:
 106         beq $0,$41
 107         EXI( ldq $2,0($17) )
 108         EXO( ldq $1,0($16) )
 109         mskql $2,$0,$2
 110         mskqh $1,$0,$1
 111         bis $2,$1,$2
 112         EXO( stq $2,0($16) )
 113         bis $31,$31,$0
 114 $41:
 115 $35:
 116 $exitin:
 117 $exitout:
 118         ret $31,($26),1
 119 
 120         .end __copy_user
 121 EXPORT_SYMBOL(__copy_user)