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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * __get_user functions.
3 *
4 * (C) Copyright 1998 Linus Torvalds
5 * (C) Copyright 2005 Andi Kleen
6 *
7 * These functions have a non-standard call interface
8 * to make them more efficient, especially as they
9 * return an error value in addition to the "real"
10 * return value.
11 */
12
13/*
14 * __get_user_X
15 *
16 * Inputs: %rcx contains the address.
17 * The register is modified, but all changes are undone
18 * before returning because the C code doesn't know about it.
19 *
20 * Outputs: %rax is error code (0 or -EFAULT)
21 * %rdx contains zero-extended value
22 *
23 * %r8 is destroyed.
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>
Jan Beulich8d379da2006-09-26 10:52:32 +020030#include <asm/dwarf2.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070031#include <asm/page.h>
32#include <asm/errno.h>
Sam Ravnborge2d5df92005-09-09 21:28:48 +020033#include <asm/asm-offsets.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034#include <asm/thread_info.h>
35
36 .text
Jan Beulich8d379da2006-09-26 10:52:32 +020037ENTRY(__get_user_1)
38 CFI_STARTPROC
Glauber Costaedf10162008-06-13 16:35:52 -030039 GET_THREAD_INFO(%rdx)
Glauber Costaef8c1a22008-06-24 11:21:53 -030040 cmp TI_addr_limit(%rdx),%rax
Linus Torvalds1da177e2005-04-16 15:20:36 -070041 jae bad_get_user
Glauber Costaedf10162008-06-13 16:35:52 -0300421: movzb (%rax),%edx
Glauber Costaef8c1a22008-06-24 11:21:53 -030043 xor %eax,%eax
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 ret
Jan Beulich8d379da2006-09-26 10:52:32 +020045 CFI_ENDPROC
46ENDPROC(__get_user_1)
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
Jan Beulich8d379da2006-09-26 10:52:32 +020048ENTRY(__get_user_2)
49 CFI_STARTPROC
Glauber Costaef8c1a22008-06-24 11:21:53 -030050 add $1,%rax
Glauber Costa92628752008-06-24 11:13:16 -030051 jc bad_get_user
52 GET_THREAD_INFO(%rdx)
Glauber Costaef8c1a22008-06-24 11:21:53 -030053 cmp TI_addr_limit(%rdx),%rax
Glauber Costa92628752008-06-24 11:13:16 -030054 jae bad_get_user
552: movzwl -1(%rax),%edx
Glauber Costaef8c1a22008-06-24 11:21:53 -030056 xor %eax,%eax
Linus Torvalds1da177e2005-04-16 15:20:36 -070057 ret
Jan Beulich8d379da2006-09-26 10:52:32 +020058 CFI_ENDPROC
59ENDPROC(__get_user_2)
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Jan Beulich8d379da2006-09-26 10:52:32 +020061ENTRY(__get_user_4)
62 CFI_STARTPROC
Glauber Costaef8c1a22008-06-24 11:21:53 -030063 add $3,%rax
Glauber Costa92628752008-06-24 11:13:16 -030064 jc bad_get_user
65 GET_THREAD_INFO(%rdx)
Glauber Costaef8c1a22008-06-24 11:21:53 -030066 cmp TI_addr_limit(%rdx),%rax
Glauber Costa92628752008-06-24 11:13:16 -030067 jae bad_get_user
Glauber Costaef8c1a22008-06-24 11:21:53 -0300683: mov -3(%rax),%edx
69 xor %eax,%eax
Linus Torvalds1da177e2005-04-16 15:20:36 -070070 ret
Jan Beulich8d379da2006-09-26 10:52:32 +020071 CFI_ENDPROC
72ENDPROC(__get_user_4)
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
Jan Beulich8d379da2006-09-26 10:52:32 +020074ENTRY(__get_user_8)
75 CFI_STARTPROC
Glauber Costaef8c1a22008-06-24 11:21:53 -030076 add $7,%rax
Glauber Costa92628752008-06-24 11:13:16 -030077 jc bad_get_user
78 GET_THREAD_INFO(%rdx)
Glauber Costaef8c1a22008-06-24 11:21:53 -030079 cmp TI_addr_limit(%rdx),%rax
Glauber Costa92628752008-06-24 11:13:16 -030080 jae bad_get_user
814: movq -7(%rax),%rdx
Glauber Costaef8c1a22008-06-24 11:21:53 -030082 xor %eax,%eax
Linus Torvalds1da177e2005-04-16 15:20:36 -070083 ret
Jan Beulich8d379da2006-09-26 10:52:32 +020084 CFI_ENDPROC
85ENDPROC(__get_user_8)
Linus Torvalds1da177e2005-04-16 15:20:36 -070086
87bad_get_user:
Jan Beulich8d379da2006-09-26 10:52:32 +020088 CFI_STARTPROC
Glauber Costaef8c1a22008-06-24 11:21:53 -030089 xor %edx,%edx
90 mov $(-EFAULT),%rax
Linus Torvalds1da177e2005-04-16 15:20:36 -070091 ret
Jan Beulich8d379da2006-09-26 10:52:32 +020092 CFI_ENDPROC
93END(bad_get_user)
Linus Torvalds1da177e2005-04-16 15:20:36 -070094
95.section __ex_table,"a"
96 .quad 1b,bad_get_user
97 .quad 2b,bad_get_user
98 .quad 3b,bad_get_user
99 .quad 4b,bad_get_user
100.previous