cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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smap.h (1617B)

      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
     30static __always_inline void clac(void)
     31{
     32	/* Note: a barrier is implicit in alternative() */
     33	alternative("", __ASM_CLAC, X86_FEATURE_SMAP);
     34}
     35
     36static __always_inline void stac(void)
     37{
     38	/* Note: a barrier is implicit in alternative() */
     39	alternative("", __ASM_STAC, X86_FEATURE_SMAP);
     40}
     41
     42static __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
     54static __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 */