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kernel/linux-rt-4.4.41/arch/x86/include/asm/smap.h 1.71 KB
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  /*
   * Supervisor Mode Access Prevention support
   *
   * Copyright (C) 2012 Intel Corporation
   * Author: H. Peter Anvin <hpa@linux.intel.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; version 2
   * of the License.
   */
  
  #ifndef _ASM_X86_SMAP_H
  #define _ASM_X86_SMAP_H
  
  #include <linux/stringify.h>
  #include <asm/nops.h>
  #include <asm/cpufeature.h>
  
  /* "Raw" instruction opcodes */
  #define __ASM_CLAC	.byte 0x0f,0x01,0xca
  #define __ASM_STAC	.byte 0x0f,0x01,0xcb
  
  #ifdef __ASSEMBLY__
  
  #include <asm/alternative-asm.h>
  
  #ifdef CONFIG_X86_SMAP
  
  #define ASM_CLAC \
  	ALTERNATIVE "", __stringify(__ASM_CLAC), X86_FEATURE_SMAP
  
  #define ASM_STAC \
  	ALTERNATIVE "", __stringify(__ASM_STAC), X86_FEATURE_SMAP
  
  #else /* CONFIG_X86_SMAP */
  
  #define ASM_CLAC
  #define ASM_STAC
  
  #endif /* CONFIG_X86_SMAP */
  
  #else /* __ASSEMBLY__ */
  
  #include <asm/alternative.h>
  
  #ifdef CONFIG_X86_SMAP
  
  static __always_inline void clac(void)
  {
  	/* Note: a barrier is implicit in alternative() */
  	alternative("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
  }
  
  static __always_inline void stac(void)
  {
  	/* Note: a barrier is implicit in alternative() */
  	alternative("", __stringify(__ASM_STAC), X86_FEATURE_SMAP);
  }
  
  /* These macros can be used in asm() statements */
  #define ASM_CLAC \
  	ALTERNATIVE("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP)
  #define ASM_STAC \
  	ALTERNATIVE("", __stringify(__ASM_STAC), X86_FEATURE_SMAP)
  
  #else /* CONFIG_X86_SMAP */
  
  static inline void clac(void) { }
  static inline void stac(void) { }
  
  #define ASM_CLAC
  #define ASM_STAC
  
  #endif /* CONFIG_X86_SMAP */
  
  #endif /* __ASSEMBLY__ */
  
  #endif /* _ASM_X86_SMAP_H */