From 8b71340d702ec5d587443b38a852671c4fb6a723 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 8 May 2019 03:02:20 -0700 Subject: [PATCH] x86/fsgsbase/64: Add intrinsics for FSGSBASE instructions [ luto: Rename the variables from FS and GS to FSBASE and GSBASE and make safe to include on 32-bit kernels. ] Signed-off-by: Andi Kleen Signed-off-by: Andy Lutomirski Signed-off-by: Chang S. Bae Signed-off-by: Thomas Gleixner Reviewed-by: Andy Lutomirski Reviewed-by: Andi Kleen Cc: Ravi Shankar Cc: H. Peter Anvin Link: https://lkml.kernel.org/r/1557309753-24073-6-git-send-email-chang.seok.bae@intel.com --- arch/x86/include/asm/fsgsbase.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h index bca4c743de77..fdd1177499b4 100644 --- a/arch/x86/include/asm/fsgsbase.h +++ b/arch/x86/include/asm/fsgsbase.h @@ -19,6 +19,36 @@ 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"); +} + /* Helper functions for reading/writing FS/GS base */ static inline unsigned long x86_fsbase_read_cpu(void) -- 2.30.2