92 lines
2.1 KiB
C
92 lines
2.1 KiB
C
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/*
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* Supervisor Mode Access Prevention support
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*
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* Copyright (C) 2012 Intel Corporation
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* Author: H. Peter Anvin <hpa@linux.intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*/
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#ifndef _ASM_X86_SMAP_H
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#define _ASM_X86_SMAP_H
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#include <linux/stringify.h>
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#include <asm/nops.h>
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#include <asm/cpufeature.h>
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/* "Raw" instruction opcodes */
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#define __ASM_CLAC .byte 0x0f,0x01,0xca
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#define __ASM_STAC .byte 0x0f,0x01,0xcb
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#ifdef __ASSEMBLY__
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#include <asm/alternative-asm.h>
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#ifdef CONFIG_X86_SMAP
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#define ASM_CLAC \
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661: ASM_NOP3 ; \
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.pushsection .altinstr_replacement, "ax" ; \
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662: __ASM_CLAC ; \
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.popsection ; \
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.pushsection .altinstructions, "a" ; \
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altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3 ; \
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.popsection
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#define ASM_STAC \
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661: ASM_NOP3 ; \
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.pushsection .altinstr_replacement, "ax" ; \
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662: __ASM_STAC ; \
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.popsection ; \
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.pushsection .altinstructions, "a" ; \
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altinstruction_entry 661b, 662b, X86_FEATURE_SMAP, 3, 3 ; \
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.popsection
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#else /* CONFIG_X86_SMAP */
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#define ASM_CLAC
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#define ASM_STAC
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#endif /* CONFIG_X86_SMAP */
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#else /* __ASSEMBLY__ */
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#include <asm/alternative.h>
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#ifdef CONFIG_X86_SMAP
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static __always_inline void clac(void)
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{
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/* Note: a barrier is implicit in alternative() */
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alternative(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
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}
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static __always_inline void stac(void)
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{
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/* Note: a barrier is implicit in alternative() */
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alternative(ASM_NOP3, __stringify(__ASM_STAC), X86_FEATURE_SMAP);
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}
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/* These macros can be used in asm() statements */
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#define ASM_CLAC \
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ALTERNATIVE(ASM_NOP3, __stringify(__ASM_CLAC), X86_FEATURE_SMAP)
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#define ASM_STAC \
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ALTERNATIVE(ASM_NOP3, __stringify(__ASM_STAC), X86_FEATURE_SMAP)
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#else /* CONFIG_X86_SMAP */
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static inline void clac(void) { }
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static inline void stac(void) { }
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#define ASM_CLAC
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#define ASM_STAC
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#endif /* CONFIG_X86_SMAP */
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_X86_SMAP_H */
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