1/*
2 * Supervisor Mode Access Prevention support
3 *
4 * Copyright (C) 2012 Intel Corporation
5 * Author: H. Peter Anvin <hpa@linux.intel.com>
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; version 2
10 * of the License.
11 */
12
13#ifndef _ASM_X86_SMAP_H
14#define _ASM_X86_SMAP_H
15
16#include <linux/stringify.h>
17#include <asm/nops.h>
18#include <asm/cpufeatures.h>
19
20/* "Raw" instruction opcodes */
21#define __ASM_CLAC .byte 0x0f,0x01,0xca
22#define __ASM_STAC .byte 0x0f,0x01,0xcb
23
24#ifdef __ASSEMBLY__
25
26#include <asm/alternative-asm.h>
27
28#ifdef CONFIG_X86_SMAP
29
30#define ASM_CLAC \
31 ALTERNATIVE "", __stringify(__ASM_CLAC), X86_FEATURE_SMAP
32
33#define ASM_STAC \
34 ALTERNATIVE "", __stringify(__ASM_STAC), X86_FEATURE_SMAP
35
36#else /* CONFIG_X86_SMAP */
37
38#define ASM_CLAC
39#define ASM_STAC
40
41#endif /* CONFIG_X86_SMAP */
42
43#else /* __ASSEMBLY__ */
44
45#include <asm/alternative.h>
46
47#ifdef CONFIG_X86_SMAP
48
49static __always_inline void clac(void)
50{
51 /* Note: a barrier is implicit in alternative() */
52 alternative("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
53}
54
55static __always_inline void stac(void)
56{
57 /* Note: a barrier is implicit in alternative() */
58 alternative("", __stringify(__ASM_STAC), X86_FEATURE_SMAP);
59}
60
61/* These macros can be used in asm() statements */
62#define ASM_CLAC \
63 ALTERNATIVE("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP)
64#define ASM_STAC \
65 ALTERNATIVE("", __stringify(__ASM_STAC), X86_FEATURE_SMAP)
66
67#else /* CONFIG_X86_SMAP */
68
69static inline void clac(void) { }
70static inline void stac(void) { }
71
72#define ASM_CLAC
73#define ASM_STAC
74
75#endif /* CONFIG_X86_SMAP */
76
77#endif /* __ASSEMBLY__ */
78
79#endif /* _ASM_X86_SMAP_H */
80