/*
* __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(%rdx)
cmp TI_addr_limit(%rdx),%rax
jae bad_get_user
1: movzb (%rax),%edx
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_1)
ENTRY(__get_user_2)
CFI_STARTPROC
add $1,%rax
jc bad_get_user
GET_THREAD_INFO(%rdx)
cmp TI_addr_limit(%rdx),%rax
jae bad_get_user
2: movzwl -1(%rax),%edx
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_2)
ENTRY(__get_user_4)
CFI_STARTPROC
add $3,%rax
jc bad_get_user
GET_THREAD_INFO(%rdx)
cmp TI_addr_limit(%rdx),%rax
jae bad_get_user
3: mov -3(%rax),%edx
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_4)
ENTRY(__get_user_8)
CFI_STARTPROC
add $7,%rax
jc bad_get_user
GET_THREAD_INFO(%rdx)
cmp TI_addr_limit(%rdx),%rax
jae bad_get_user
4: movq -7(%rax),%rdx
xor %eax,%eax
ret
CFI_ENDPROC
ENDPROC(__get_user_8)
bad_get_user:
CFI_STARTPROC
xor %edx,%edx
mov $(-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
