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 |