LXR linux/arch/x86/include/asm/smap.h

   1/*
   2 * Supervisor Mode Access Prevention support
   3 *
   4 * Copyright (C) 2012 Intel Corporation
   5 * Author: H. Peter Anvin <hpa@linux.intel.com>
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License
   9 * as published by the Free Software Foundation; version 2
  10 * of the License.
  11 */
  12
  13#ifndef _ASM_X86_SMAP_H
  14#define _ASM_X86_SMAP_H
  15
  16#include <linux/stringify.h>
  17#include <asm/nops.h>
  18#include <asm/cpufeatures.h>
  19
  20/* "Raw" instruction opcodes */
  21#define __ASM_CLAC      .byte 0x0f,0x01,0xca
  22#define __ASM_STAC      .byte 0x0f,0x01,0xcb
  23
  24#ifdef __ASSEMBLY__
  25
  26#include <asm/alternative-asm.h>
  27
  28#ifdef CONFIG_X86_SMAP
  29
  30#define ASM_CLAC \
  31        ALTERNATIVE "", __stringify(__ASM_CLAC), X86_FEATURE_SMAP
  32
  33#define ASM_STAC \
  34        ALTERNATIVE "", __stringify(__ASM_STAC), X86_FEATURE_SMAP
  35
  36#else /* CONFIG_X86_SMAP */
  37
  38#define ASM_CLAC
  39#define ASM_STAC
  40
  41#endif /* CONFIG_X86_SMAP */
  42
  43#else /* __ASSEMBLY__ */
  44
  45#include <asm/alternative.h>
  46
  47#ifdef CONFIG_X86_SMAP
  48
  49static __always_inline void clac(void)
  50{
  51        /* Note: a barrier is implicit in alternative() */
  52        alternative("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP);
  53}
  54
  55static __always_inline void stac(void)
  56{
  57        /* Note: a barrier is implicit in alternative() */
  58        alternative("", __stringify(__ASM_STAC), X86_FEATURE_SMAP);
  59}
  60
  61/* These macros can be used in asm() statements */
  62#define ASM_CLAC \
  63        ALTERNATIVE("", __stringify(__ASM_CLAC), X86_FEATURE_SMAP)
  64#define ASM_STAC \
  65        ALTERNATIVE("", __stringify(__ASM_STAC), X86_FEATURE_SMAP)
  66
  67#else /* CONFIG_X86_SMAP */
  68
  69static inline void clac(void) { }
  70static inline void stac(void) { }
  71
  72#define ASM_CLAC
  73#define ASM_STAC
  74
  75#endif /* CONFIG_X86_SMAP */
  76
  77#endif /* __ASSEMBLY__ */
  78
  79#endif /* _ASM_X86_SMAP_H */
  80