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 #include <asm/smap.h>
  19
  20
  21 /*
  22  * __put_user_X
  23  *
  24  * Inputs:      %eax[:%edx] contains the data
  25  *              %ecx contains the address
  26  *
  27  * Outputs:     %eax is error code (0 or -EFAULT)
  28  *
  29  * These functions should not modify any other registers,
  30  * as they get called from within inline assembly.
  31  */
  32
  33 #define ENTER   CFI_STARTPROC ; \
  34                 GET_THREAD_INFO(%_ASM_BX)
  35 #define EXIT    ASM_CLAC ;      \
  36                 ret ;           \
  37                 CFI_ENDPROC
  38
  39 .text
  40 ENTRY(__put_user_1)
  41         ENTER
  42         cmp TI_addr_limit(%_ASM_BX),%_ASM_CX
  43         jae bad_put_user
  44         ASM_STAC
  45 1:      movb %al,(%_ASM_CX)
  46         xor %eax,%eax
  47         EXIT
  48 ENDPROC(__put_user_1)
  49
  50 ENTRY(__put_user_2)
  51         ENTER
  52         mov TI_addr_limit(%_ASM_BX),%_ASM_BX
  53         sub $1,%_ASM_BX
  54         cmp %_ASM_BX,%_ASM_CX
  55         jae bad_put_user
  56         ASM_STAC
  57 2:      movw %ax,(%_ASM_CX)
  58         xor %eax,%eax
  59         EXIT
  60 ENDPROC(__put_user_2)
  61
  62 ENTRY(__put_user_4)
  63         ENTER
  64         mov TI_addr_limit(%_ASM_BX),%_ASM_BX
  65         sub $3,%_ASM_BX
  66         cmp %_ASM_BX,%_ASM_CX
  67         jae bad_put_user
  68         ASM_STAC
  69 3:      movl %eax,(%_ASM_CX)
  70         xor %eax,%eax
  71         EXIT
  72 ENDPROC(__put_user_4)
  73
  74 ENTRY(__put_user_8)
  75         ENTER
  76         mov TI_addr_limit(%_ASM_BX),%_ASM_BX
  77         sub $7,%_ASM_BX
  78         cmp %_ASM_BX,%_ASM_CX
  79         jae bad_put_user
  80         ASM_STAC
  81 4:      mov %_ASM_AX,(%_ASM_CX)
  82 #ifdef CONFIG_X86_32
  83 5:      movl %edx,4(%_ASM_CX)
  84 #endif
  85         xor %eax,%eax
  86         EXIT
  87 ENDPROC(__put_user_8)
  88
  89 bad_put_user:
  90         CFI_STARTPROC
  91         movl $-EFAULT,%eax
  92         EXIT
  93 END(bad_put_user)
  94
  95         _ASM_EXTABLE(1b,bad_put_user)
  96         _ASM_EXTABLE(2b,bad_put_user)
  97         _ASM_EXTABLE(3b,bad_put_user)
  98         _ASM_EXTABLE(4b,bad_put_user)
  99 #ifdef CONFIG_X86_32
 100         _ASM_EXTABLE(5b,bad_put_user)
 101 #endif