1 /* SPDX-License-Identifier: GPL-2.0-only */
3 * Supervisor Mode Access Prevention support
5 * Copyright (C) 2012 Intel Corporation
6 * Author: H. Peter Anvin <hpa@linux.intel.com>
9 #ifndef _ASM_X86_SMAP_H
10 #define _ASM_X86_SMAP_H
13 #include <asm/cpufeatures.h>
15 /* "Raw" instruction opcodes */
16 #define __ASM_CLAC ".byte 0x0f,0x01,0xca"
17 #define __ASM_STAC ".byte 0x0f,0x01,0xcb"
21 #include <asm/alternative-asm.h>
23 #ifdef CONFIG_X86_SMAP
26 ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP
29 ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP
31 #else /* CONFIG_X86_SMAP */
36 #endif /* CONFIG_X86_SMAP */
38 #else /* __ASSEMBLY__ */
40 #include <asm/alternative.h>
42 #ifdef CONFIG_X86_SMAP
44 static __always_inline void clac(void)
46 /* Note: a barrier is implicit in alternative() */
47 alternative("", __ASM_CLAC, X86_FEATURE_SMAP);
50 static __always_inline void stac(void)
52 /* Note: a barrier is implicit in alternative() */
53 alternative("", __ASM_STAC, X86_FEATURE_SMAP);
56 static __always_inline unsigned long smap_save(void)
60 asm volatile ("# smap_save\n\t"
61 ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t",
63 : "=rm" (flags) : : "memory", "cc");
68 static __always_inline void smap_restore(unsigned long flags)
70 asm volatile ("# smap_restore\n\t"
71 ALTERNATIVE("", "push %0; popf\n\t",
73 : : "g" (flags) : "memory", "cc");
76 /* These macros can be used in asm() statements */
78 ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP)
80 ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP)
82 #else /* CONFIG_X86_SMAP */
84 static inline void clac(void) { }
85 static inline void stac(void) { }
87 static inline unsigned long smap_save(void) { return 0; }
88 static inline void smap_restore(unsigned long flags) { }
93 #endif /* CONFIG_X86_SMAP */
95 #endif /* __ASSEMBLY__ */
97 #endif /* _ASM_X86_SMAP_H */