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             : 
      15             : /* "Raw" instruction opcodes */
      16             : #define __ASM_CLAC      ".byte 0x0f,0x01,0xca"
      17             : #define __ASM_STAC      ".byte 0x0f,0x01,0xcb"
      18             : 
      19             : #ifdef __ASSEMBLY__
      20             : 
      21             : #include <asm/alternative-asm.h>
      22             : 
      23             : #ifdef CONFIG_X86_SMAP
      24             : 
      25             : #define ASM_CLAC \
      26             :         ALTERNATIVE "", __ASM_CLAC, X86_FEATURE_SMAP
      27             : 
      28             : #define ASM_STAC \
      29             :         ALTERNATIVE "", __ASM_STAC, X86_FEATURE_SMAP
      30             : 
      31             : #else /* CONFIG_X86_SMAP */
      32             : 
      33             : #define ASM_CLAC
      34             : #define ASM_STAC
      35             : 
      36             : #endif /* CONFIG_X86_SMAP */
      37             : 
      38             : #else /* __ASSEMBLY__ */
      39             : 
      40             : #include <asm/alternative.h>
      41             : 
      42             : #ifdef CONFIG_X86_SMAP
      43             : 
      44             : static __always_inline void clac(void)
      45             : {
      46             :         /* Note: a barrier is implicit in alternative() */
      47             :         alternative("", __ASM_CLAC, X86_FEATURE_SMAP);
      48             : }
      49             : 
      50             : static __always_inline void stac(void)
      51             : {
      52             :         /* Note: a barrier is implicit in alternative() */
      53             :         alternative("", __ASM_STAC, X86_FEATURE_SMAP);
      54             : }
      55             : 
      56             : static __always_inline unsigned long smap_save(void)
      57             : {
      58             :         unsigned long flags;
      59             : 
      60             :         asm volatile ("# smap_save\n\t"
      61             :                       ALTERNATIVE("", "pushf; pop %0; " __ASM_CLAC "\n\t",
      62             :                                   X86_FEATURE_SMAP)
      63             :                       : "=rm" (flags) : : "memory", "cc");
      64             : 
      65             :         return flags;
      66             : }
      67             : 
      68             : static __always_inline void smap_restore(unsigned long flags)
      69             : {
      70             :         asm volatile ("# smap_restore\n\t"
      71             :                       ALTERNATIVE("", "push %0; popf\n\t",
      72             :                                   X86_FEATURE_SMAP)
      73             :                       : : "g" (flags) : "memory", "cc");
      74             : }
      75             : 
      76             : /* These macros can be used in asm() statements */
      77             : #define ASM_CLAC \
      78             :         ALTERNATIVE("", __ASM_CLAC, X86_FEATURE_SMAP)
      79             : #define ASM_STAC \
      80             :         ALTERNATIVE("", __ASM_STAC, X86_FEATURE_SMAP)
      81             : 
      82             : #else /* CONFIG_X86_SMAP */
      83             : 
      84      310517 : static inline void clac(void) { }
      85        9851 : static inline void stac(void) { }
      86             : 
      87       59947 : static inline unsigned long smap_save(void) { return 0; }
      88       59947 : static inline void smap_restore(unsigned long flags) { }
      89             : 
      90             : #define ASM_CLAC
      91             : #define ASM_STAC
      92             : 
      93             : #endif /* CONFIG_X86_SMAP */
      94             : 
      95             : #endif /* __ASSEMBLY__ */
      96             : 
      97             : #endif /* _ASM_X86_SMAP_H */