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 *		The register is modified, but all changes are undone
19 *		before returning because the C code doesn't know about it.
20 *
21 * Outputs:	%[r|e]ax is error code (0 or -EFAULT)
22 *		%[r|e]dx contains zero-extended value
23 *
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>
30#include <asm/dwarf2.h>
31#include <asm/page_types.h>
32#include <asm/errno.h>
33#include <asm/asm-offsets.h>
34#include <asm/thread_info.h>
35#include <asm/asm.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
431:	movzb (%_ASM_AX),%edx
44	xor %eax,%eax
45	ret
46	CFI_ENDPROC
47ENDPROC(__get_user_1)
48
49ENTRY(__get_user_2)
50	CFI_STARTPROC
51	add $1,%_ASM_AX
52	jc bad_get_user
53	GET_THREAD_INFO(%_ASM_DX)
54	cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
55	jae bad_get_user
562:	movzwl -1(%_ASM_AX),%edx
57	xor %eax,%eax
58	ret
59	CFI_ENDPROC
60ENDPROC(__get_user_2)
61
62ENTRY(__get_user_4)
63	CFI_STARTPROC
64	add $3,%_ASM_AX
65	jc bad_get_user
66	GET_THREAD_INFO(%_ASM_DX)
67	cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
68	jae bad_get_user
693:	mov -3(%_ASM_AX),%edx
70	xor %eax,%eax
71	ret
72	CFI_ENDPROC
73ENDPROC(__get_user_4)
74
75#ifdef CONFIG_X86_64
76ENTRY(__get_user_8)
77	CFI_STARTPROC
78	add $7,%_ASM_AX
79	jc bad_get_user
80	GET_THREAD_INFO(%_ASM_DX)
81	cmp TI_addr_limit(%_ASM_DX),%_ASM_AX
82	jae	bad_get_user
834:	movq -7(%_ASM_AX),%_ASM_DX
84	xor %eax,%eax
85	ret
86	CFI_ENDPROC
87ENDPROC(__get_user_8)
88#endif
89
90bad_get_user:
91	CFI_STARTPROC
92	xor %edx,%edx
93	mov $(-EFAULT),%_ASM_AX
94	ret
95	CFI_ENDPROC
96END(bad_get_user)
97
98.section __ex_table,"a"
99	_ASM_PTR 1b,bad_get_user
100	_ASM_PTR 2b,bad_get_user
101	_ASM_PTR 3b,bad_get_user
102#ifdef CONFIG_X86_64
103	_ASM_PTR 4b,bad_get_user
104#endif
105