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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pkru.h (1346B)

      1/* SPDX-License-Identifier: GPL-2.0 */
      2#ifndef _ASM_X86_PKRU_H
      3#define _ASM_X86_PKRU_H
      4
      5#include <asm/cpufeature.h>
      6
      7#define PKRU_AD_BIT 0x1u
      8#define PKRU_WD_BIT 0x2u
      9#define PKRU_BITS_PER_PKEY 2
     10
     11#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
     12extern u32 init_pkru_value;
     13#define pkru_get_init_value()	READ_ONCE(init_pkru_value)
     14#else
     15#define init_pkru_value	0
     16#define pkru_get_init_value()	0
     17#endif
     18
     19static inline bool __pkru_allows_read(u32 pkru, u16 pkey)
     20{
     21	int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
     22	return !(pkru & (PKRU_AD_BIT << pkru_pkey_bits));
     23}
     24
     25static inline bool __pkru_allows_write(u32 pkru, u16 pkey)
     26{
     27	int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
     28	/*
     29	 * Access-disable disables writes too so we need to check
     30	 * both bits here.
     31	 */
     32	return !(pkru & ((PKRU_AD_BIT|PKRU_WD_BIT) << pkru_pkey_bits));
     33}
     34
     35static inline u32 read_pkru(void)
     36{
     37	if (cpu_feature_enabled(X86_FEATURE_OSPKE))
     38		return rdpkru();
     39	return 0;
     40}
     41
     42static inline void write_pkru(u32 pkru)
     43{
     44	if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
     45		return;
     46	/*
     47	 * WRPKRU is relatively expensive compared to RDPKRU.
     48	 * Avoid WRPKRU when it would not change the value.
     49	 */
     50	if (pkru != rdpkru())
     51		wrpkru(pkru);
     52}
     53
     54static inline void pkru_write_default(void)
     55{
     56	if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
     57		return;
     58
     59	wrpkru(pkru_get_init_value());
     60}
     61
     62#endif