xref: /openbmc/linux/arch/x86/lib/putuser.S (revision 3381df09)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3  * __put_user functions.
4  *
5  * (C) Copyright 2005 Linus Torvalds
6  * (C) Copyright 2005 Andi Kleen
7  * (C) Copyright 2008 Glauber Costa
8  *
9  * These functions have a non-standard call interface
10  * to make them more efficient, especially as they
11  * return an error value in addition to the "real"
12  * return value.
13  */
14 #include <linux/linkage.h>
15 #include <asm/thread_info.h>
16 #include <asm/errno.h>
17 #include <asm/asm.h>
18 #include <asm/smap.h>
19 #include <asm/export.h>
20 
21 
22 /*
23  * __put_user_X
24  *
25  * Inputs:	%eax[:%edx] contains the data
26  *		%ecx contains the address
27  *
28  * Outputs:	%eax is error code (0 or -EFAULT)
29  *
30  * These functions should not modify any other registers,
31  * as they get called from within inline assembly.
32  */
33 
34 #define ENTER	mov PER_CPU_VAR(current_task), %_ASM_BX
35 
36 .text
37 SYM_FUNC_START(__put_user_1)
38 	ENTER
39 	cmp TASK_addr_limit(%_ASM_BX),%_ASM_CX
40 	jae .Lbad_put_user
41 	ASM_STAC
42 1:	movb %al,(%_ASM_CX)
43 	xor %eax,%eax
44 	ASM_CLAC
45 	ret
46 SYM_FUNC_END(__put_user_1)
47 EXPORT_SYMBOL(__put_user_1)
48 
49 SYM_FUNC_START(__put_user_2)
50 	ENTER
51 	mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
52 	sub $1,%_ASM_BX
53 	cmp %_ASM_BX,%_ASM_CX
54 	jae .Lbad_put_user
55 	ASM_STAC
56 2:	movw %ax,(%_ASM_CX)
57 	xor %eax,%eax
58 	ASM_CLAC
59 	ret
60 SYM_FUNC_END(__put_user_2)
61 EXPORT_SYMBOL(__put_user_2)
62 
63 SYM_FUNC_START(__put_user_4)
64 	ENTER
65 	mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
66 	sub $3,%_ASM_BX
67 	cmp %_ASM_BX,%_ASM_CX
68 	jae .Lbad_put_user
69 	ASM_STAC
70 3:	movl %eax,(%_ASM_CX)
71 	xor %eax,%eax
72 	ASM_CLAC
73 	ret
74 SYM_FUNC_END(__put_user_4)
75 EXPORT_SYMBOL(__put_user_4)
76 
77 SYM_FUNC_START(__put_user_8)
78 	ENTER
79 	mov TASK_addr_limit(%_ASM_BX),%_ASM_BX
80 	sub $7,%_ASM_BX
81 	cmp %_ASM_BX,%_ASM_CX
82 	jae .Lbad_put_user
83 	ASM_STAC
84 4:	mov %_ASM_AX,(%_ASM_CX)
85 #ifdef CONFIG_X86_32
86 5:	movl %edx,4(%_ASM_CX)
87 #endif
88 	xor %eax,%eax
89 	ASM_CLAC
90 	RET
91 SYM_FUNC_END(__put_user_8)
92 EXPORT_SYMBOL(__put_user_8)
93 
94 SYM_CODE_START_LOCAL(.Lbad_put_user_clac)
95 	ASM_CLAC
96 .Lbad_put_user:
97 	movl $-EFAULT,%eax
98 	RET
99 SYM_CODE_END(.Lbad_put_user_clac)
100 
101 	_ASM_EXTABLE_UA(1b, .Lbad_put_user_clac)
102 	_ASM_EXTABLE_UA(2b, .Lbad_put_user_clac)
103 	_ASM_EXTABLE_UA(3b, .Lbad_put_user_clac)
104 	_ASM_EXTABLE_UA(4b, .Lbad_put_user_clac)
105 #ifdef CONFIG_X86_32
106 	_ASM_EXTABLE_UA(5b, .Lbad_put_user_clac)
107 #endif
108