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x86/fpu: Turn WARN_ON() in context switch into WARN_ON_FPU() 

copy_xregs_to_kernel checks if the alternatives have been already
patched.

This WARN_ON() is always executed in every context switch.

All the other checks in fpu internal.h are WARN_ON_FPU(), but
this one is plain WARN_ON(). I assume it was forgotten to switch it.

So switch it to WARN_ON_FPU() too to avoid some unnecessary code
in the context switch, and a potentially expensive cache line miss for the
global variable.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170329062605.4970-1-andi@firstfloor.org
Link: http://lkml.kernel.org/r/20170923130016.21448-24-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andi Kleen 2017-09-23 15:00:06 +02:00 committed by Ingo Molnar
parent 4f8cef59ba
commit 03eaec81ac
1 changed files with 1 additions and 1 deletions
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2
arch/x86/include/asm/fpu/internal.h
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@ -350,7 +350,7 @@ static inline void copy_xregs_to_kernel(struct xregs_state *xstate)
u32 hmask = mask >> 32;
int err;
WARN_ON(!alternatives_patched);
WARN_ON_FPU(!alternatives_patched);
XSTATE_XSAVE(xstate, lmask, hmask, err);