arch/x86_64/lib/putuser.S

   1 /*
   2  * __put_user functions.
   3  *
   4  * (C) Copyright 1998 Linus Torvalds
   5  * (C) Copyright 2005 Andi Kleen
   6  *
   7  * These functions have a non-standard call interface
   8  * to make them more efficient, especially as they
   9  * return an error value in addition to the "real"
  10  * return value.
  11  */
  12
  13 /*
  14  * __put_user_X
  15  *
  16  * Inputs:      %rcx contains the address
  17  *              %rdx contains new value
  18  *
  19  * Outputs:     %rax is error code (0 or -EFAULT)
  20  *
  21  * %r8 is destroyed.
  22  *
  23  * These functions should not modify any other registers,
  24  * as they get called from within inline assembly.
  25  */
  26
  27 #include <linux/linkage.h>
  28 #include <asm/page.h>
  29 #include <asm/errno.h>
  30 #include <asm/offset.h>
  31 #include <asm/thread_info.h>
  32
  33         .text
  34         .p2align 4
  35 .globl __put_user_1
  36 __put_user_1:
  37         GET_THREAD_INFO(%r8)
  38         cmpq threadinfo_addr_limit(%r8),%rcx
  39         jae bad_put_user
  40 1:      movb %dl,(%rcx)
  41         xorl %eax,%eax
  42         ret
  43
  44         .p2align 4
  45 .globl __put_user_2
  46 __put_user_2:
  47         GET_THREAD_INFO(%r8)
  48         addq $1,%rcx
  49         jc bad_put_user
  50         cmpq threadinfo_addr_limit(%r8),%rcx
  51         jae      bad_put_user
  52 2:      movw %dx,-1(%rcx)
  53         xorl %eax,%eax
  54         ret
  55
  56         .p2align 4
  57 .globl __put_user_4
  58 __put_user_4:
  59         GET_THREAD_INFO(%r8)
  60         addq $3,%rcx
  61         jc bad_put_user
  62         cmpq threadinfo_addr_limit(%r8),%rcx
  63         jae bad_put_user
  64 3:      movl %edx,-3(%rcx)
  65         xorl %eax,%eax
  66         ret
  67
  68         .p2align 4
  69 .globl __put_user_8
  70 __put_user_8:
  71         GET_THREAD_INFO(%r8)
  72         addq $7,%rcx
  73         jc bad_put_user
  74         cmpq threadinfo_addr_limit(%r8),%rcx
  75         jae     bad_put_user
  76 4:      movq %rdx,-7(%rcx)
  77         xorl %eax,%eax
  78         ret
  79
  80 bad_put_user:
  81         movq $(-EFAULT),%rax
  82         ret
  83
  84 .section __ex_table,"a"
  85         .quad 1b,bad_put_user
  86         .quad 2b,bad_put_user
  87         .quad 3b,bad_put_user
  88         .quad 4b,bad_put_user
  89 .previous