| 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 |