1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef _ASM_FSGSBASE_H |
3 | #define _ASM_FSGSBASE_H |
4 | |
5 | #ifndef __ASSEMBLY__ |
6 | |
7 | #ifdef CONFIG_X86_64 |
8 | |
9 | #include <asm/msr-index.h> |
10 | |
11 | /* |
12 | * Read/write a task's FSBASE or GSBASE. This returns the value that |
13 | * the FS/GS base would have (if the task were to be resumed). These |
14 | * work on the current task or on a non-running (typically stopped |
15 | * ptrace child) task. |
16 | */ |
17 | extern unsigned long x86_fsbase_read_task(struct task_struct *task); |
18 | extern unsigned long x86_gsbase_read_task(struct task_struct *task); |
19 | extern void x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase); |
20 | extern void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase); |
21 | |
22 | /* Must be protected by X86_FEATURE_FSGSBASE check. */ |
23 | |
24 | static __always_inline unsigned long rdfsbase(void) |
25 | { |
26 | unsigned long fsbase; |
27 | |
28 | asm volatile("rdfsbase %0" : "=r" (fsbase) :: "memory" ); |
29 | |
30 | return fsbase; |
31 | } |
32 | |
33 | static __always_inline unsigned long rdgsbase(void) |
34 | { |
35 | unsigned long gsbase; |
36 | |
37 | asm volatile("rdgsbase %0" : "=r" (gsbase) :: "memory" ); |
38 | |
39 | return gsbase; |
40 | } |
41 | |
42 | static __always_inline void wrfsbase(unsigned long fsbase) |
43 | { |
44 | asm volatile("wrfsbase %0" :: "r" (fsbase) : "memory" ); |
45 | } |
46 | |
47 | static __always_inline void wrgsbase(unsigned long gsbase) |
48 | { |
49 | asm volatile("wrgsbase %0" :: "r" (gsbase) : "memory" ); |
50 | } |
51 | |
52 | #include <asm/cpufeature.h> |
53 | |
54 | /* Helper functions for reading/writing FS/GS base */ |
55 | |
56 | static inline unsigned long x86_fsbase_read_cpu(void) |
57 | { |
58 | unsigned long fsbase; |
59 | |
60 | if (boot_cpu_has(X86_FEATURE_FSGSBASE)) |
61 | fsbase = rdfsbase(); |
62 | else |
63 | rdmsrl(MSR_FS_BASE, fsbase); |
64 | |
65 | return fsbase; |
66 | } |
67 | |
68 | static inline void x86_fsbase_write_cpu(unsigned long fsbase) |
69 | { |
70 | if (boot_cpu_has(X86_FEATURE_FSGSBASE)) |
71 | wrfsbase(fsbase); |
72 | else |
73 | wrmsrl(MSR_FS_BASE, val: fsbase); |
74 | } |
75 | |
76 | extern unsigned long x86_gsbase_read_cpu_inactive(void); |
77 | extern void x86_gsbase_write_cpu_inactive(unsigned long gsbase); |
78 | extern unsigned long x86_fsgsbase_read_task(struct task_struct *task, |
79 | unsigned short selector); |
80 | |
81 | #endif /* CONFIG_X86_64 */ |
82 | |
83 | #endif /* __ASSEMBLY__ */ |
84 | |
85 | #endif /* _ASM_FSGSBASE_H */ |
86 | |