summaryrefslogtreecommitdiff
path: root/arch/x86/include/asm/fsgsbase.h
blob: bca4c743de77c6d80f21f1bb4aeb0e2a188d824b (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_FSGSBASE_H
#define _ASM_FSGSBASE_H

#ifndef __ASSEMBLY__

#ifdef CONFIG_X86_64

#include <asm/msr-index.h>

/*
 * Read/write a task's FSBASE or GSBASE. This returns the value that
 * the FS/GS base would have (if the task were to be resumed). These
 * work on the current task or on a non-running (typically stopped
 * ptrace child) task.
 */
extern unsigned long x86_fsbase_read_task(struct task_struct *task);
extern unsigned long x86_gsbase_read_task(struct task_struct *task);
extern void x86_fsbase_write_task(struct task_struct *task, unsigned long fsbase);
extern void x86_gsbase_write_task(struct task_struct *task, unsigned long gsbase);

/* Helper functions for reading/writing FS/GS base */

static inline unsigned long x86_fsbase_read_cpu(void)
{
	unsigned long fsbase;

	rdmsrl(MSR_FS_BASE, fsbase);

	return fsbase;
}

static inline unsigned long x86_gsbase_read_cpu_inactive(void)
{
	unsigned long gsbase;

	rdmsrl(MSR_KERNEL_GS_BASE, gsbase);

	return gsbase;
}

static inline void x86_fsbase_write_cpu(unsigned long fsbase)
{
	wrmsrl(MSR_FS_BASE, fsbase);
}

static inline void x86_gsbase_write_cpu_inactive(unsigned long gsbase)
{
	wrmsrl(MSR_KERNEL_GS_BASE, gsbase);
}

#endif /* CONFIG_X86_64 */

#endif /* __ASSEMBLY__ */

#endif /* _ASM_FSGSBASE_H */