arch/x86/lib/putuser.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * __put_user functions.
   4  *
   5  * (C) Copyright 2005 Linus Torvalds
   6  * (C) Copyright 2005 Andi Kleen
   7  * (C) Copyright 2008 Glauber Costa
   8  *
   9  * These functions have a non-standard call interface
  10  * to make them more efficient, especially as they
  11  * return an error value in addition to the "real"
  12  * return value.
  13  */
  14 #include <linux/linkage.h>
  15 #include <asm/thread_info.h>
  16 #include <asm/errno.h>
  17 #include <asm/asm.h>
  18 #include <asm/smap.h>
  19 #include <asm/export.h>
  20
  21
  22 /*
  23  * __put_user_X
  24  *
  25  * Inputs:      %eax[:%edx] contains the data
  26  *              %ecx contains the address
  27  *
  28  * Outputs:     %eax is error code (0 or -EFAULT)
  29  *
  30  * These functions should not modify any other registers,
  31  * as they get called from within inline assembly.
  32  */
  33
  34 #define ENTER   mov PER_CPU_VAR(current_task), %_ASM_BX
  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         ASM_CLAC
  45         ret
  46 ENDPROC(__put_user_1)
  47 EXPORT_SYMBOL(__put_user_1)
  48
  49 ENTRY(__put_user_2)
  50         ENTER
  51         mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
  52         sub $1,%_ASM_BX
  53         cmp %_ASM_BX,%_ASM_CX
  54         jae bad_put_user
  55         ASM_STAC
  56 2:      movw %ax,(%_ASM_CX)
  57         xor %eax,%eax
  58         ASM_CLAC
  59         ret
  60 ENDPROC(__put_user_2)
  61 EXPORT_SYMBOL(__put_user_2)
  62
  63 ENTRY(__put_user_4)
  64         ENTER
  65         mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
  66         sub $3,%_ASM_BX
  67         cmp %_ASM_BX,%_ASM_CX
  68         jae bad_put_user
  69         ASM_STAC
  70 3:      movl %eax,(%_ASM_CX)
  71         xor %eax,%eax
  72         ASM_CLAC
  73         ret
  74 ENDPROC(__put_user_4)
  75 EXPORT_SYMBOL(__put_user_4)
  76
  77 ENTRY(__put_user_8)
  78         ENTER
  79         mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
  80         sub $7,%_ASM_BX
  81         cmp %_ASM_BX,%_ASM_CX
  82         jae bad_put_user
  83         ASM_STAC
  84 4:      mov %_ASM_AX,(%_ASM_CX)
  85 #ifdef CONFIG_X86_32
  86 5:      movl %edx,4(%_ASM_CX)
  87 #endif
  88         xor %eax,%eax
  89         ASM_CLAC
  90         RET
  91 ENDPROC(__put_user_8)
  92 EXPORT_SYMBOL(__put_user_8)
  93
  94 bad_put_user_clac:
  95         ASM_CLAC
  96 bad_put_user:
  97         movl $-EFAULT,%eax
  98         RET
  99
 100         _ASM_EXTABLE_UA(1b, bad_put_user_clac)
 101         _ASM_EXTABLE_UA(2b, bad_put_user_clac)
 102         _ASM_EXTABLE_UA(3b, bad_put_user_clac)
 103         _ASM_EXTABLE_UA(4b, bad_put_user_clac)
 104 #ifdef CONFIG_X86_32
 105         _ASM_EXTABLE_UA(5b, bad_put_user_clac)
 106 #endif