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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * __get_user functions.
3 *
4 * (C) Copyright 1998 Linus Torvalds
5 *
6 * These functions have a non-standard call interface
7 * to make them more efficient, especially as they
8 * return an error value in addition to the "real"
9 * return value.
10 */
11#include <asm/thread_info.h>
12
13
14/*
15 * __get_user_X
16 *
17 * Inputs: %eax contains the address
18 *
19 * Outputs: %eax is error code (0 or -EFAULT)
20 * %edx contains zero-extended value
21 *
22 * These functions should not modify any other registers,
23 * as they get called from within inline assembly.
24 */
25
26.text
27.align 4
28.globl __get_user_1
29__get_user_1:
30 GET_THREAD_INFO(%edx)
31 cmpl TI_addr_limit(%edx),%eax
32 jae bad_get_user
331: movzbl (%eax),%edx
34 xorl %eax,%eax
35 ret
36
37.align 4
38.globl __get_user_2
39__get_user_2:
40 addl $1,%eax
41 jc bad_get_user
42 GET_THREAD_INFO(%edx)
43 cmpl TI_addr_limit(%edx),%eax
44 jae bad_get_user
452: movzwl -1(%eax),%edx
46 xorl %eax,%eax
47 ret
48
49.align 4
50.globl __get_user_4
51__get_user_4:
52 addl $3,%eax
53 jc bad_get_user
54 GET_THREAD_INFO(%edx)
55 cmpl TI_addr_limit(%edx),%eax
56 jae bad_get_user
573: movl -3(%eax),%edx
58 xorl %eax,%eax
59 ret
60
61bad_get_user:
62 xorl %edx,%edx
63 movl $-14,%eax
64 ret
65
66.section __ex_table,"a"
67 .long 1b,bad_get_user
68 .long 2b,bad_get_user
69 .long 3b,bad_get_user
70.previous