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 12 extern 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 19 static 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 25 static 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 35 static inline u32 read_pkru(void) 36 { 37 if (cpu_feature_enabled(X86_FEATURE_OSPKE)) 38 return rdpkru(); 39 return 0; 40 } 41 42 static 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 54 static 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 63