arch/x86/lib/getuser.S

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * __get_user functions.
   4  *
   5  * (C) Copyright 1998 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
  15 /*
  16  * __get_user_X
  17  *
  18  * Inputs:      %[r|e]ax contains the address.
  19  *
  20  * Outputs:     %[r|e]ax is error code (0 or -EFAULT)
  21  *              %[r|e]dx contains zero-extended value
  22  *              %ecx contains the high half for 32-bit __get_user_8
  23  *
  24  *
  25  * These functions should not modify any other registers,
  26  * as they get called from within inline assembly.
  27  */
  28
  29 #include <linux/linkage.h>
  30 #include <asm/page_types.h>
  31 #include <asm/errno.h>
  32 #include <asm/asm-offsets.h>
  33 #include <asm/thread_info.h>
  34 #include <asm/asm.h>
  35 #include <asm/smap.h>
  36 #include <asm/export.h>
  37
  38         .text
  39 ENTRY(__get_user_1)
  40         mov PER_CPU_VAR(current_task), %_ASM_DX
  41         cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
  42         jae bad_get_user
  43         ASM_STAC
  44 1:      movzbl (%_ASM_AX),%edx
  45         xor %eax,%eax
  46         ASM_CLAC
  47         ret
  48 ENDPROC(__get_user_1)
  49 EXPORT_SYMBOL(__get_user_1)
  50
  51 ENTRY(__get_user_2)
  52         add $1,%_ASM_AX
  53         jc bad_get_user
  54         mov PER_CPU_VAR(current_task), %_ASM_DX
  55         cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
  56         jae bad_get_user
  57         ASM_STAC
  58 2:      movzwl -1(%_ASM_AX),%edx
  59         xor %eax,%eax
  60         ASM_CLAC
  61         ret
  62 ENDPROC(__get_user_2)
  63 EXPORT_SYMBOL(__get_user_2)
  64
  65 ENTRY(__get_user_4)
  66         add $3,%_ASM_AX
  67         jc bad_get_user
  68         mov PER_CPU_VAR(current_task), %_ASM_DX
  69         cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
  70         jae bad_get_user
  71         ASM_STAC
  72 3:      movl -3(%_ASM_AX),%edx
  73         xor %eax,%eax
  74         ASM_CLAC
  75         ret
  76 ENDPROC(__get_user_4)
  77 EXPORT_SYMBOL(__get_user_4)
  78
  79 ENTRY(__get_user_8)
  80 #ifdef CONFIG_X86_64
  81         add $7,%_ASM_AX
  82         jc bad_get_user
  83         mov PER_CPU_VAR(current_task), %_ASM_DX
  84         cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
  85         jae bad_get_user
  86         ASM_STAC
  87 4:      movq -7(%_ASM_AX),%rdx
  88         xor %eax,%eax
  89         ASM_CLAC
  90         ret
  91 #else
  92         add $7,%_ASM_AX
  93         jc bad_get_user_8
  94         mov PER_CPU_VAR(current_task), %_ASM_DX
  95         cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
  96         jae bad_get_user_8
  97         ASM_STAC
  98 4:      movl -7(%_ASM_AX),%edx
  99 5:      movl -3(%_ASM_AX),%ecx
 100         xor %eax,%eax
 101         ASM_CLAC
 102         ret
 103 #endif
 104 ENDPROC(__get_user_8)
 105 EXPORT_SYMBOL(__get_user_8)
 106
 107
 108 bad_get_user:
 109         xor %edx,%edx
 110         mov $(-EFAULT),%_ASM_AX
 111         ASM_CLAC
 112         ret
 113 END(bad_get_user)
 114
 115 #ifdef CONFIG_X86_32
 116 bad_get_user_8:
 117         xor %edx,%edx
 118         xor %ecx,%ecx
 119         mov $(-EFAULT),%_ASM_AX
 120         ASM_CLAC
 121         ret
 122 END(bad_get_user_8)
 123 #endif
 124
 125         _ASM_EXTABLE(1b,bad_get_user)
 126         _ASM_EXTABLE(2b,bad_get_user)
 127         _ASM_EXTABLE(3b,bad_get_user)
 128 #ifdef CONFIG_X86_64
 129         _ASM_EXTABLE(4b,bad_get_user)
 130 #else
 131         _ASM_EXTABLE(4b,bad_get_user_8)
 132         _ASM_EXTABLE(5b,bad_get_user_8)
 133 #endif