xref: /linux/arch/x86/lib/getuser.S (revision 10accd2e6890b57db8e717e9aee91b791f90fe14)
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/page_types.h>
30#include <asm/errno.h>
31#include <asm/asm-offsets.h>
32#include <asm/thread_info.h>
33#include <asm/asm.h>
34#include <asm/smap.h>
35
36	.text
37ENTRY(__get_user_1)
38	mov PER_CPU_VAR(current_task), %_ASM_DX
39	cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
40	jae bad_get_user
41	ASM_STAC
421:	movzbl (%_ASM_AX),%edx
43	xor %eax,%eax
44	ASM_CLAC
45	ret
46ENDPROC(__get_user_1)
47
48ENTRY(__get_user_2)
49	add $1,%_ASM_AX
50	jc bad_get_user
51	mov PER_CPU_VAR(current_task), %_ASM_DX
52	cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
53	jae bad_get_user
54	ASM_STAC
552:	movzwl -1(%_ASM_AX),%edx
56	xor %eax,%eax
57	ASM_CLAC
58	ret
59ENDPROC(__get_user_2)
60
61ENTRY(__get_user_4)
62	add $3,%_ASM_AX
63	jc bad_get_user
64	mov PER_CPU_VAR(current_task), %_ASM_DX
65	cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
66	jae bad_get_user
67	ASM_STAC
683:	movl -3(%_ASM_AX),%edx
69	xor %eax,%eax
70	ASM_CLAC
71	ret
72ENDPROC(__get_user_4)
73
74ENTRY(__get_user_8)
75#ifdef CONFIG_X86_64
76	add $7,%_ASM_AX
77	jc bad_get_user
78	mov PER_CPU_VAR(current_task), %_ASM_DX
79	cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
80	jae bad_get_user
81	ASM_STAC
824:	movq -7(%_ASM_AX),%rdx
83	xor %eax,%eax
84	ASM_CLAC
85	ret
86#else
87	add $7,%_ASM_AX
88	jc bad_get_user_8
89	mov PER_CPU_VAR(current_task), %_ASM_DX
90	cmp TASK_addr_limit(%_ASM_DX),%_ASM_AX
91	jae bad_get_user_8
92	ASM_STAC
934:	movl -7(%_ASM_AX),%edx
945:	movl -3(%_ASM_AX),%ecx
95	xor %eax,%eax
96	ASM_CLAC
97	ret
98#endif
99ENDPROC(__get_user_8)
100
101
102bad_get_user:
103	xor %edx,%edx
104	mov $(-EFAULT),%_ASM_AX
105	ASM_CLAC
106	ret
107END(bad_get_user)
108
109#ifdef CONFIG_X86_32
110bad_get_user_8:
111	xor %edx,%edx
112	xor %ecx,%ecx
113	mov $(-EFAULT),%_ASM_AX
114	ASM_CLAC
115	ret
116END(bad_get_user_8)
117#endif
118
119	_ASM_EXTABLE(1b,bad_get_user)
120	_ASM_EXTABLE(2b,bad_get_user)
121	_ASM_EXTABLE(3b,bad_get_user)
122#ifdef CONFIG_X86_64
123	_ASM_EXTABLE(4b,bad_get_user)
124#else
125	_ASM_EXTABLE(4b,bad_get_user_8)
126	_ASM_EXTABLE(5b,bad_get_user_8)
127#endif
128