[PATCH 04/15] x86/fsgsbase/64: Factor out load FS/GS segments from __switch_to

[Chang S. Bae]

Instead of open code, load_fsgs() will cleanup __switch_to
and symmetric with FS/GS segment save. When FSGSBASE
enabled, X86_FEATURE_FSGSBASE check will be incorporated.

Signed-off-by: Chang S. Bae <chang.seok....@intel.com>
Reviewed-by: Andi Kleen <a...@linux.intel.com>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: H. Peter Anvin <h...@zytor.com>
---
 arch/x86/kernel/process_64.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 2375f10..4488f07 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -265,6 +265,15 @@ static __always_inline void load_seg_legacy(unsigned short 
prev_index,
        }
 }
 
+static __always_inline void load_fsgs(struct thread_struct *prev,
+                                     struct thread_struct *next)
+{
+       load_seg_legacy(prev->fsindex, prev->fsbase,
+                       next->fsindex, next->fsbase, FS);
+       load_seg_legacy(prev->gsindex, prev->gsbase,
+                       next->gsindex, next->gsbase, GS);
+}
+
 static unsigned long task_seg_base(struct task_struct *task,
                                   unsigned short selector)
 {
@@ -574,10 +583,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct 
*next_p)
        if (unlikely(next->ds | prev->ds))
                loadsegment(ds, next->ds);
 
-       load_seg_legacy(prev->fsindex, prev->fsbase,
-                       next->fsindex, next->fsbase, FS);
-       load_seg_legacy(prev->gsindex, prev->gsbase,
-                       next->gsindex, next->gsbase, GS);
+       load_fsgs(prev, next);
 
        switch_fpu_finish(next_fpu, cpu);
 
-- 
2.7.4