text: /* SPDX-License-Identifier: GPL-2.0-only */
  /*
   * Supervisor Mode Access Prevention support
   *
   * Copyright (C) 2012 Intel Corporation
   * Author: H. Peter Anvin <hpa@linux.intel.com>
   */
  
  #ifndef _ASM_X86_SMAP_H
  #define _ASM_X86_SMAP_H
  
  #include <asm/nops.h>
  #include <asm/cpufeatures.h>
  #include <asm/alternative.h>
  
  /* "Raw" instruction opcodes */
  #define __ASM_CLAC	".byte 0x0f,0x01,0xca"
  #define __ASM_STAC	".byte 0x0f,0x01,0xcb"
  
  #ifdef __ASSEMBLY__
  
  #ifdef CONFIG_X86_SMAP
  
  #define ASM_CLAC \
  	ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP
  
  #define ASM_STAC \
  	ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP
  
  #else /* CONFIG_X86_SMAP */
  
  #define ASM_CLAC
  #define ASM_STAC
  
  #endif /* CONFIG_X86_SMAP */
  
  #else /* __ASSEMBLY__ */
  
  #ifdef CONFIG_X86_SMAP
  
  static __always_inline void clac(void)
  {
  	/* Note: a barrier is implicit in alternative() */
  	alternative("", __ASM_CLAC, X86_FEATURE_SMAP);
  }
  
  static __always_inline void stac(void)
  {
  	/* Note: a barrier is implicit in alternative() */
  	alternative("", __ASM_STAC, X86_FEATURE_SMAP);
  }
  
  static __always_inline unsigned long smap_save(void)
  {
  	unsigned long flags;
  
  	asm volatile ("# smap_save\n\t"
  		      ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t",
  				  X86_FEATURE_SMAP)
  		      : "=rm" (flags) : : "memory", "cc");
  
  	return flags;
  }
  
  static __always_inline void smap_restore(unsigned long flags)
  {
  	asm volatile ("# smap_restore\n\t"
  		      ALTERNATIVE("", "push %0; popf\n\t",
  				  X86_FEATURE_SMAP)
  		      : : "g" (flags) : "memory", "cc");
  }
  
  /* These macros can be used in asm() statements */
  #define ASM_CLAC \
  	ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP)
  #define ASM_STAC \
  	ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP)
  
  #else /* CONFIG_X86_SMAP */
  
  static inline void clac(void) { }
  static inline void stac(void) { }
  
  static inline unsigned long smap_save(void) { return 0; }
  static inline void smap_restore(unsigned long flags) { }
  
  #define ASM_CLAC
  #define ASM_STAC
  
  #endif /* CONFIG_X86_SMAP */
  
  #endif /* __ASSEMBLY__ */
  
  #endif /* _ASM_X86_SMAP_H */
  