Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * __get_user functions.
3 *
4 * (C) Copyright 1998 Linus Torvalds
5 * (C) Copyright 2005 Andi Kleen
6 * (C) Copyright 2008 Glauber Costa
7 *
8 * These functions have a non-standard call interface
9 * to make them more efficient, especially as they
10 * return an error value in addition to the "real"
11 * return value.
12 */
13
14/*
15 * __get_user_X
16 *
17 * Inputs: %[r|e]ax contains the address.
18 *
19 * Outputs: %[r|e]ax is error code (0 or -EFAULT)
20 * %[r|e]dx contains zero-extended value
21 * %ecx contains the high half for 32-bit __get_user_8
22 *
23 *
24 * These functions should not modify any other registers,
25 * as they get called from within inline assembly.
26 */
27
28#include <linux/linkage.h>
29#include <asm/dwarf2.h>
30#include <asm/page_types.h>
31#include <asm/errno.h>
32#include <asm/asm-offsets.h>
33#include <asm/thread_info.h>
34#include <asm/asm.h>
35#include <asm/smap.h>
36
37 .text
38ENTRY(__get_user_1)
39 CFI_STARTPROC
40 GET_THREAD_INFO(%_ASM_DX)
41 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
42 jae bad_get_user
43 ASM_STAC
441: movzbl (%_ASM_AX),%edx
45 xor %eax,%eax
46 ASM_CLAC
47 ret
48 CFI_ENDPROC
49ENDPROC(__get_user_1)
50
51ENTRY(__get_user_2)
52 CFI_STARTPROC
53 add $1,%_ASM_AX
54 jc bad_get_user
55 GET_THREAD_INFO(%_ASM_DX)
56 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
57 jae bad_get_user
58 ASM_STAC
592: movzwl -1(%_ASM_AX),%edx
60 xor %eax,%eax
61 ASM_CLAC
62 ret
63 CFI_ENDPROC
64ENDPROC(__get_user_2)
65
66ENTRY(__get_user_4)
67 CFI_STARTPROC
68 add $3,%_ASM_AX
69 jc bad_get_user
70 GET_THREAD_INFO(%_ASM_DX)
71 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
72 jae bad_get_user
73 ASM_STAC
743: movl -3(%_ASM_AX),%edx
75 xor %eax,%eax
76 ASM_CLAC
77 ret
78 CFI_ENDPROC
79ENDPROC(__get_user_4)
80
81ENTRY(__get_user_8)
82 CFI_STARTPROC
83#ifdef CONFIG_X86_64
84 add $7,%_ASM_AX
85 jc bad_get_user
86 GET_THREAD_INFO(%_ASM_DX)
87 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
88 jae bad_get_user
89 ASM_STAC
904: movq -7(%_ASM_AX),%rdx
91 xor %eax,%eax
92 ASM_CLAC
93 ret
94#else
95 add $7,%_ASM_AX
96 jc bad_get_user_8
97 GET_THREAD_INFO(%_ASM_DX)
98 cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
99 jae bad_get_user_8
100 ASM_STAC
1014: movl -7(%_ASM_AX),%edx
1025: movl -3(%_ASM_AX),%ecx
103 xor %eax,%eax
104 ASM_CLAC
105 ret
106#endif
107 CFI_ENDPROC
108ENDPROC(__get_user_8)
109
110
111bad_get_user:
112 CFI_STARTPROC
113 xor %edx,%edx
114 mov $(-EFAULT),%_ASM_AX
115 ASM_CLAC
116 ret
117 CFI_ENDPROC
118END(bad_get_user)
119
120#ifdef CONFIG_X86_32
121bad_get_user_8:
122 CFI_STARTPROC
123 xor %edx,%edx
124 xor %ecx,%ecx
125 mov $(-EFAULT),%_ASM_AX
126 ASM_CLAC
127 ret
128 CFI_ENDPROC
129END(bad_get_user_8)
130#endif
131
132 _ASM_EXTABLE(1b,bad_get_user)
133 _ASM_EXTABLE(2b,bad_get_user)
134 _ASM_EXTABLE(3b,bad_get_user)
135#ifdef CONFIG_X86_64
136 _ASM_EXTABLE(4b,bad_get_user)
137#else
138 _ASM_EXTABLE(4b,bad_get_user_8)
139 _ASM_EXTABLE(5b,bad_get_user_8)
140#endif