Line data    Source code

       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             : /* "Raw" instruction opcodes */
      17             : #define __ASM_CLAC      ".byte 0x0f,0x01,0xca"
      18             : #define __ASM_STAC      ".byte 0x0f,0x01,0xcb"
      19             : 
      20             : #ifdef __ASSEMBLY__
      21             : 
      22             : #define ASM_CLAC \
      23             :         ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP
      24             : 
      25             : #define ASM_STAC \
      26             :         ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP
      27             : 
      28             : #else /* __ASSEMBLY__ */
      29             : 
      30             : static __always_inline void clac(void)
      31             : {
      32             :         /* Note: a barrier is implicit in alternative() */
      33 28242902596 :         alternative("", __ASM_CLAC, X86_FEATURE_SMAP);
      34         891 : }
      35             : 
      36             : static __always_inline void stac(void)
      37             : {
      38             :         /* Note: a barrier is implicit in alternative() */
      39 28346612744 :         alternative("", __ASM_STAC, X86_FEATURE_SMAP);
      40             : }
      41             : 
      42             : static __always_inline unsigned long smap_save(void)
      43             : {
      44             :         unsigned long flags;
      45             : 
      46             :         asm volatile ("# smap_save\n\t"
      47             :                       ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t",
      48             :                                   X86_FEATURE_SMAP)
      49             :                       : "=rm" (flags) : : "memory", "cc");
      50             : 
      51             :         return flags;
      52             : }
      53             : 
      54             : static __always_inline void smap_restore(unsigned long flags)
      55             : {
      56             :         asm volatile ("# smap_restore\n\t"
      57             :                       ALTERNATIVE("", "push %0; popf\n\t",
      58             :                                   X86_FEATURE_SMAP)
      59             :                       : : "g" (flags) : "memory", "cc");
      60             : }
      61             : 
      62             : /* These macros can be used in asm() statements */
      63             : #define ASM_CLAC \
      64             :         ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP)
      65             : #define ASM_STAC \
      66             :         ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP)
      67             : 
      68             : #endif /* __ASSEMBLY__ */
      69             : 
      70             : #endif /* _ASM_X86_SMAP_H */