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/dwarf2.h>
  15 #include <asm/thread_info.h>
  16 #include <asm/errno.h>
  17 #include <asm/asm.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   CFI_STARTPROC ; \
  33                 GET_THREAD_INFO(%_ASM_BX)
  34 #define EXIT    ret ; \
  35                 CFI_ENDPROC
  36
  37 .text
  38 ENTRY(__put_user_1)
  39         ENTER
  40         cmp TI_addr_limit(%_ASM_BX),%_ASM_CX
  41         jae bad_put_user
  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 TI_addr_limit(%_ASM_BX),%_ASM_BX
  50         sub $1,%_ASM_BX
  51         cmp %_ASM_BX,%_ASM_CX
  52         jae bad_put_user
  53 2:      movw %ax,(%_ASM_CX)
  54         xor %eax,%eax
  55         EXIT
  56 ENDPROC(__put_user_2)
  57
  58 ENTRY(__put_user_4)
  59         ENTER
  60         mov TI_addr_limit(%_ASM_BX),%_ASM_BX
  61         sub $3,%_ASM_BX
  62         cmp %_ASM_BX,%_ASM_CX
  63         jae bad_put_user
  64 3:      movl %eax,(%_ASM_CX)
  65         xor %eax,%eax
  66         EXIT
  67 ENDPROC(__put_user_4)
  68
  69 ENTRY(__put_user_8)
  70         ENTER
  71         mov TI_addr_limit(%_ASM_BX),%_ASM_BX
  72         sub $7,%_ASM_BX
  73         cmp %_ASM_BX,%_ASM_CX
  74         jae bad_put_user
  75 4:      mov %_ASM_AX,(%_ASM_CX)
  76 #ifdef CONFIG_X86_32
  77 5:      movl %edx,4(%_ASM_CX)
  78 #endif
  79         xor %eax,%eax
  80         EXIT
  81 ENDPROC(__put_user_8)
  82
  83 bad_put_user:
  84         CFI_STARTPROC
  85         movl $-EFAULT,%eax
  86         EXIT
  87 END(bad_put_user)
  88
  89 .section __ex_table,"a"
  90         _ASM_PTR 1b,bad_put_user
  91         _ASM_PTR 2b,bad_put_user
  92         _ASM_PTR 3b,bad_put_user
  93         _ASM_PTR 4b,bad_put_user
  94 #ifdef CONFIG_X86_32
  95         _ASM_PTR 5b,bad_put_user
  96 #endif
  97 .previous