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x86/fsgsbase/64: Factor out FS/GS segment loading from __switch_to()

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Instead of open coding the calls to load_seg_legacy(), introduce
x86_fsgsbase_load() to load FS/GS segments.

This makes it more explicit that this is part of FSGSBASE functionality,
and the new helper can be updated when FSGSBASE instructions are enabled.

[ mingo: Wrote new changelog. ]

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Markus T Metzger <markus.t.metzger@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Rik van Riel <riel@surriel.com>
Link: http://lkml.kernel.org/r/1537312139-5580-6-git-send-email-chang.seok.bae@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Chang S. Bae 2018-09-18 16:08:56 -07:00 committed by Ingo Molnar
parent 824eea38d2
commit f4550b52e4
1 changed files with 10 additions and 4 deletions
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14
arch/x86/kernel/process_64.c
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@ -287,6 +287,15 @@ static __always_inline void load_seg_legacy(unsigned short prev_index,
} }
} }
static __always_inline void x86_fsgsbase_load(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 x86_fsgsbase_read_task(struct task_struct *task, static unsigned long x86_fsgsbase_read_task(struct task_struct *task,
unsigned short selector) unsigned short selector)
{ {
@ -597,10 +606,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
if (unlikely(next->ds | prev->ds)) if (unlikely(next->ds | prev->ds))
loadsegment(ds, next->ds); loadsegment(ds, next->ds);
load_seg_legacy(prev->fsindex, prev->fsbase, x86_fsgsbase_load(prev, next);
next->fsindex, next->fsbase, FS);
load_seg_legacy(prev->gsindex, prev->gsbase,
next->gsindex, next->gsbase, GS);
switch_fpu_finish(next_fpu, cpu); switch_fpu_finish(next_fpu, cpu);