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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_PKRU_H
#define _ASM_X86_PKRU_H
#include <asm/cpufeature.h>
#define PKRU_AD_BIT 0x1u
#define PKRU_WD_BIT 0x2u
#define PKRU_BITS_PER_PKEY 2
#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
extern u32 init_pkru_value;
#define pkru_get_init_value() READ_ONCE(init_pkru_value)
#else
#define init_pkru_value 0
#define pkru_get_init_value() 0
#endif
static inline bool __pkru_allows_read(u32 pkru, u16 pkey)
{
int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
return !(pkru & (PKRU_AD_BIT << pkru_pkey_bits));
}
static inline bool __pkru_allows_write(u32 pkru, u16 pkey)
{
int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
/*
* Access-disable disables writes too so we need to check
* both bits here.
*/
return !(pkru & ((PKRU_AD_BIT|PKRU_WD_BIT) << pkru_pkey_bits));
}
static inline u32 read_pkru(void)
{
if (cpu_feature_enabled(X86_FEATURE_OSPKE))
return rdpkru();
return 0;
}
static inline void write_pkru(u32 pkru)
{
if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
return;
/*
* WRPKRU is relatively expensive compared to RDPKRU.
* Avoid WRPKRU when it would not change the value.
*/
if (pkru != rdpkru())
wrpkru(pkru);
}
static inline void pkru_write_default(void)
{
if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
return;
wrpkru(pkru_get_init_value());
}
#endif
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