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/*
* __get_user functions.
*
* (C) Copyright 1998 Linus Torvalds
* (C) Copyright 2005 Andi Kleen
*
* 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: %rcx contains the address.
* The register is modified, but all changes are undone
* before returning because the C code doesn't know about it.
*
* Outputs: %rax is error code (0 or -EFAULT)
* %rdx contains zero-extended value
*
* %r8 is destroyed.
*
* 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.h>
#include <asm/errno.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
.text
ENTRY(__get_user_1)
CFI_STARTPROC
GET_THREAD_INFO(%r8)
cmpq threadinfo_addr_limit(%r8),%rcx
jae bad_get_user
1: movzb (%rcx),%edx
xorl %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_1)
ENTRY(__get_user_2)
CFI_STARTPROC
GET_THREAD_INFO(%r8)
addq $1,%rcx
jc 20f
cmpq threadinfo_addr_limit(%r8),%rcx
jae 20f
decq %rcx
2: movzwl (%rcx),%edx
xorl %eax,%eax
ret
20: decq %rcx
jmp bad_get_user
CFI_ENDPROC
ENDPROC(__get_user_2)
ENTRY(__get_user_4)
CFI_STARTPROC
GET_THREAD_INFO(%r8)
addq $3,%rcx
jc 30f
cmpq threadinfo_addr_limit(%r8),%rcx
jae 30f
subq $3,%rcx
3: movl (%rcx),%edx
xorl %eax,%eax
ret
30: subq $3,%rcx
jmp bad_get_user
CFI_ENDPROC
ENDPROC(__get_user_4)
ENTRY(__get_user_8)
CFI_STARTPROC
GET_THREAD_INFO(%r8)
addq $7,%rcx
jc 40f
cmpq threadinfo_addr_limit(%r8),%rcx
jae 40f
subq $7,%rcx
4: movq (%rcx),%rdx
xorl %eax,%eax
ret
40: subq $7,%rcx
jmp bad_get_user
CFI_ENDPROC
ENDPROC(__get_user_8)
bad_get_user:
CFI_STARTPROC
xorl %edx,%edx
movq $(-EFAULT),%rax
ret
CFI_ENDPROC
END(bad_get_user)
.section __ex_table,"a"
.quad 1b,bad_get_user
.quad 2b,bad_get_user
.quad 3b,bad_get_user
.quad 4b,bad_get_user
.previous
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