arch/x86/lib/putuser.S

   1 /*
   2  * __put_user functions.
   3  *
   4  * (C) Copyright 2005 Linus Torvalds
   5  * (C) Copyright 2005 Andi Kleen
   6  * (C) Copyright 2008 Glauber Costa
   7  *
   8  * These functions have a non-standard call interface
   9  * to make them more efficient, especially as they
  10  * return an error value in addition to the "real"
  11  * return value.
  12  */
  13 #include <linux/linkage.h>
  14 #include <asm/thread_info.h>
  15 #include <asm/errno.h>
  16 #include <asm/asm.h>
  17 #include <asm/smap.h>
  18
  19
  20 /*
  21  * __put_user_X
  22  *
  23  * Inputs:      %eax[:%edx] contains the data
  24  *              %ecx contains the address
  25  *
  26  * Outputs:     %eax is error code (0 or -EFAULT)
  27  *
  28  * These functions should not modify any other registers,
  29  * as they get called from within inline assembly.
  30  */
  31
  32 #define ENTER   mov PER_CPU_VAR(current_task), %_ASM_BX
  33 #define EXIT    ASM_CLAC ;      \
  34                 ret
  35
  36 .text
  37 ENTRY(__put_user_1)
  38         ENTER
  39         cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
  40         jae bad_put_user
  41         ASM_STAC
  42 1:      movb %al,(%_ASM_CX)
  43         xor %eax,%eax
  44         EXIT
  45 ENDPROC(__put_user_1)
  46
  47 ENTRY(__put_user_2)
  48         ENTER
  49         mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
  50         sub $1,%_ASM_BX
  51         cmp %_ASM_BX,%_ASM_CX
  52         jae bad_put_user
  53         ASM_STAC
  54 2:      movw %ax,(%_ASM_CX)
  55         xor %eax,%eax
  56         EXIT
  57 ENDPROC(__put_user_2)
  58
  59 ENTRY(__put_user_4)
  60         ENTER
  61         mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
  62         sub $3,%_ASM_BX
  63         cmp %_ASM_BX,%_ASM_CX
  64         jae bad_put_user
  65         ASM_STAC
  66 3:      movl %eax,(%_ASM_CX)
  67         xor %eax,%eax
  68         EXIT
  69 ENDPROC(__put_user_4)
  70
  71 ENTRY(__put_user_8)
  72         ENTER
  73         mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
  74         sub $7,%_ASM_BX
  75         cmp %_ASM_BX,%_ASM_CX
  76         jae bad_put_user
  77         ASM_STAC
  78 4:      mov %_ASM_AX,(%_ASM_CX)
  79 #ifdef CONFIG_X86_32
  80 5:      movl %edx,4(%_ASM_CX)
  81 #endif
  82         xor %eax,%eax
  83         EXIT
  84 ENDPROC(__put_user_8)
  85
  86 bad_put_user:
  87         movl $-EFAULT,%eax
  88         EXIT
  89 END(bad_put_user)
  90
  91         _ASM_EXTABLE(1b,bad_put_user)
  92         _ASM_EXTABLE(2b,bad_put_user)
  93         _ASM_EXTABLE(3b,bad_put_user)
  94         _ASM_EXTABLE(4b,bad_put_user)
  95 #ifdef CONFIG_X86_32
  96         _ASM_EXTABLE(5b,bad_put_user)
  97 #endif