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
26static __always_inline void clac(void)
27{
28 /* Note: a barrier is implicit in alternative() */
29 alternative("", "clac", X86_FEATURE_SMAP);
30}
31
32static __always_inline void stac(void)
33{
34 /* Note: a barrier is implicit in alternative() */
35 alternative("", "stac", X86_FEATURE_SMAP);
36}
37
38static __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
51static __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