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 #ifdef __ASSEMBLER__
17
18 #define ASM_CLAC \
19 ALTERNATIVE "", "clac", X86_FEATURE_SMAP
20
21 #define ASM_STAC \
22 ALTERNATIVE "", "stac", X86_FEATURE_SMAP
23
24 #else /* __ASSEMBLER__ */
25
clac(void)26 static __always_inline void clac(void)
27 {
28 /* Note: a barrier is implicit in alternative() */
29 alternative("", "clac", X86_FEATURE_SMAP);
30 }
31
stac(void)32 static __always_inline void stac(void)
33 {
34 /* Note: a barrier is implicit in alternative() */
35 alternative("", "stac", X86_FEATURE_SMAP);
36 }
37
smap_save(void)38 static __always_inline unsigned long smap_save(void)
39 {
40 unsigned long flags;
41
42 asm volatile ("# smap_save\n\t"
43 ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE
44 "", "pushf; pop %0; clac",
45 X86_FEATURE_SMAP)
46 : "=rm" (flags) : : "memory", "cc");
47
48 return flags;
49 }
50
smap_restore(unsigned long flags)51 static __always_inline void smap_restore(unsigned long flags)
52 {
53 asm volatile ("# smap_restore\n\t"
54 ALTERNATIVE(ANNOTATE_IGNORE_ALTERNATIVE
55 "", "push %0; popf",
56 X86_FEATURE_SMAP)
57 : : "g" (flags) : "memory", "cc");
58 }
59
60 /* These macros can be used in asm() statements */
61 #define ASM_CLAC \
62 ALTERNATIVE("", "clac", X86_FEATURE_SMAP)
63 #define ASM_STAC \
64 ALTERNATIVE("", "stac", X86_FEATURE_SMAP)
65
66 #define ASM_CLAC_UNSAFE \
67 ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "clac", X86_FEATURE_SMAP)
68 #define ASM_STAC_UNSAFE \
69 ALTERNATIVE("", ANNOTATE_IGNORE_ALTERNATIVE "stac", X86_FEATURE_SMAP)
70
71 #endif /* __ASSEMBLER__ */
72
73 #endif /* _ASM_X86_SMAP_H */
74