/* | |
* __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/page.h> | |
#include <asm/errno.h> | |
#include <asm/offset.h> | |
#include <asm/thread_info.h> | |
.text | |
.p2align 4 | |
.globl __get_user_1 | |
__get_user_1: | |
GET_THREAD_INFO(%r8) | |
cmpq threadinfo_addr_limit(%r8),%rcx | |
jae bad_get_user | |
1: movzb (%rcx),%edx | |
xorl %eax,%eax | |
ret | |
.p2align 4 | |
.globl __get_user_2 | |
__get_user_2: | |
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 | |
.p2align 4 | |
.globl __get_user_4 | |
__get_user_4: | |
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 | |
.p2align 4 | |
.globl __get_user_8 | |
__get_user_8: | |
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 | |
bad_get_user: | |
xorl %edx,%edx | |
movq $(-EFAULT),%rax | |
ret | |
.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 |