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 */

 1/* SPDX-License-Identifier: GPL-2.0-only */
 2/*
 3 * Supervisor Mode Access Prevention support
 4 *
 5 * Copyright (C) 2012 Intel Corporation
 6 * Author: H. Peter Anvin <hpa@linux.intel.com>
 
 
 
 
 
 7 */
 8
 9#ifndef _ASM_X86_SMAP_H
10#define _ASM_X86_SMAP_H
11
 
12#include <asm/nops.h>
13#include <asm/cpufeatures.h>
14#include <asm/alternative.h>
15
16/* "Raw" instruction opcodes */
17#define __ASM_CLAC	".byte 0x0f,0x01,0xca"
18#define __ASM_STAC	".byte 0x0f,0x01,0xcb"
19
20#ifdef __ASSEMBLY__
21
 
 
 
 
22#define ASM_CLAC \
23	ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP
24
25#define ASM_STAC \
26	ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP
 
 
 
 
 
 
 
27
28#else /* __ASSEMBLY__ */
29
 
 
 
 
30static __always_inline void clac(void)
31{
32	/* Note: a barrier is implicit in alternative() */
33	alternative("", __ASM_CLAC, X86_FEATURE_SMAP);
34}
35
36static __always_inline void stac(void)
37{
38	/* Note: a barrier is implicit in alternative() */
39	alternative("", __ASM_STAC, X86_FEATURE_SMAP);
40}
41
42static __always_inline unsigned long smap_save(void)
43{
44	unsigned long flags;
 
 
45
46	asm volatile ("# smap_save\n\t"
47		      ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t",
48				  X86_FEATURE_SMAP)
49		      : "=rm" (flags) : : "memory", "cc");
50
51	return flags;
52}
53
54static __always_inline void smap_restore(unsigned long flags)
55{
56	asm volatile ("# smap_restore\n\t"
57		      ALTERNATIVE("", "push %0; popf\n\t",
58				  X86_FEATURE_SMAP)
59		      : : "g" (flags) : "memory", "cc");
60}
61
62/* These macros can be used in asm() statements */
63#define ASM_CLAC \
64	ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP)
65#define ASM_STAC \
66	ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP)
67
68#endif /* __ASSEMBLY__ */
69
70#endif /* _ASM_X86_SMAP_H */