1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_PKRU_H
3 #define _ASM_X86_PKRU_H
5 #include <asm/cpufeature.h>
7 #define PKRU_AD_BIT 0x1u
8 #define PKRU_WD_BIT 0x2u
9 #define PKRU_BITS_PER_PKEY 2
11 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
12 extern u32 init_pkru_value;
13 #define pkru_get_init_value() READ_ONCE(init_pkru_value)
15 #define init_pkru_value 0
16 #define pkru_get_init_value() 0
19 static inline bool __pkru_allows_read(u32 pkru, u16 pkey)
21 int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
22 return !(pkru & (PKRU_AD_BIT << pkru_pkey_bits));
25 static inline bool __pkru_allows_write(u32 pkru, u16 pkey)
27 int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY;
29 * Access-disable disables writes too so we need to check
32 return !(pkru & ((PKRU_AD_BIT|PKRU_WD_BIT) << pkru_pkey_bits));
35 static inline u32 read_pkru(void)
37 if (cpu_feature_enabled(X86_FEATURE_OSPKE))
42 static inline void write_pkru(u32 pkru)
44 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
47 * WRPKRU is relatively expensive compared to RDPKRU.
48 * Avoid WRPKRU when it would not change the value.
54 static inline void pkru_write_default(void)
56 if (!cpu_feature_enabled(X86_FEATURE_OSPKE))
59 wrpkru(pkru_get_init_value());