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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_FSGSBASE_H
#define _ASM_FSGSBASE_H
#ifndef __ASSEMBLY__
#ifdef CONFIG_X86_64
#include <asm/msr.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);
/* Must be protected by X86_FEATURE_FSGSBASE check. */
static __always_inline unsigned long rdfsbase(void)
{
unsigned long fsbase;
asm volatile("rdfsbase %0" : "=r" (fsbase) :: "memory");
return fsbase;
}
static __always_inline unsigned long rdgsbase(void)
{
unsigned long gsbase;
asm volatile("rdgsbase %0" : "=r" (gsbase) :: "memory");
return gsbase;
}
static __always_inline void wrfsbase(unsigned long fsbase)
{
asm volatile("wrfsbase %0" :: "r" (fsbase) : "memory");
}
static __always_inline void wrgsbase(unsigned long gsbase)
{
asm volatile("wrgsbase %0" :: "r" (gsbase) : "memory");
}
#include <asm/cpufeature.h>
/* Helper functions for reading/writing FS/GS base */
static inline unsigned long x86_fsbase_read_cpu(void)
{
unsigned long fsbase;
if (boot_cpu_has(X86_FEATURE_FSGSBASE))
fsbase = rdfsbase();
else
rdmsrl(MSR_FS_BASE, fsbase);
return fsbase;
}
static inline void x86_fsbase_write_cpu(unsigned long fsbase)
{
if (boot_cpu_has(X86_FEATURE_FSGSBASE))
wrfsbase(fsbase);
else
wrmsrl(MSR_FS_BASE, fsbase);
}
extern unsigned long x86_gsbase_read_cpu_inactive(void);
extern void x86_gsbase_write_cpu_inactive(unsigned long gsbase);
extern unsigned long x86_fsgsbase_read_task(struct task_struct *task,
unsigned short selector);
#endif /* CONFIG_X86_64 */
#endif /* __ASSEMBLY__ */
#endif /* _ASM_FSGSBASE_H */
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