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/*
* __get_user functions.
*
* (C) Copyright 1998 Linus Torvalds
* (C) Copyright 2005 Andi Kleen
* (C) Copyright 2008 Glauber Costa
*
* These functions have a non-standard call interface
* to make them more efficient, especially as they
* return an error value in addition to the "real"
* return value.
*/
/*
* __get_user_X
*
* Inputs: %[r|e]ax contains the address.
* The register is modified, but all changes are undone
* before returning because the C code doesn't know about it.
*
* Outputs: %[r|e]ax is error code (0 or -EFAULT)
* %[r|e]dx contains zero-extended value
*
*
* These functions should not modify any other registers,
* as they get called from within inline assembly.
*/
#include <linux/linkage.h>
#include <asm/dwarf2.h>
#include <asm/page_types.h>
#include <asm/errno.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/asm.h>
.text
ENTRY(__get_user_1)
CFI_STARTPROC
GET_THREAD_INFO(%_ASM_DX)
cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
jae bad_get_user
1: movzb (%_ASM_AX),%edx
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_1)
ENTRY(__get_user_2)
CFI_STARTPROC
add $1,%_ASM_AX
jc bad_get_user
GET_THREAD_INFO(%_ASM_DX)
cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
jae bad_get_user
2: movzwl -1(%_ASM_AX),%edx
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_2)
ENTRY(__get_user_4)
CFI_STARTPROC
add $3,%_ASM_AX
jc bad_get_user
GET_THREAD_INFO(%_ASM_DX)
cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
jae bad_get_user
3: mov -3(%_ASM_AX),%edx
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_4)
#ifdef CONFIG_X86_64
ENTRY(__get_user_8)
CFI_STARTPROC
add $7,%_ASM_AX
jc bad_get_user
GET_THREAD_INFO(%_ASM_DX)
cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
jae bad_get_user
4: movq -7(%_ASM_AX),%_ASM_DX
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_8)
#endif
bad_get_user:
CFI_STARTPROC
xor %edx,%edx
mov $(-EFAULT),%_ASM_AX
ret
CFI_ENDPROC
END(bad_get_user)
_ASM_EXTABLE(1b,bad_get_user)
_ASM_EXTABLE(2b,bad_get_user)
_ASM_EXTABLE(3b,bad_get_user)
#ifdef CONFIG_X86_64
_ASM_EXTABLE(4b,bad_get_user)
#endif
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