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 /* Helper functions for reading/writing FS/GS base */ 23 24 static inline unsigned long x86_fsbase_read_cpu(void) 25 { 26 unsigned long fsbase; 27 28 rdmsrl(MSR_FS_BASE, fsbase); 29 30 return fsbase; 31 } 32 33 static inline unsigned long x86_gsbase_read_cpu_inactive(void) 34 { 35 unsigned long gsbase; 36 37 rdmsrl(MSR_KERNEL_GS_BASE, gsbase); 38 39 return gsbase; 40 } 41 42 static inline void x86_fsbase_write_cpu(unsigned long fsbase) 43 { 44 wrmsrl(MSR_FS_BASE, fsbase); 45 } 46 47 static inline void x86_gsbase_write_cpu_inactive(unsigned long gsbase) 48 { 49 wrmsrl(MSR_KERNEL_GS_BASE, gsbase); 50 } 51 52 #endif /* CONFIG_X86_64 */ 53 54 #endif /* __ASSEMBLY__ */ 55 56 #endif /* _ASM_FSGSBASE_H */ 57