x86: fix taking DNA during 64bit sigreturn

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restore sigcontext is taking a DNA exception while restoring FP context
from the user stack, during the sigreturn.  Appended patch fixes it by
doing clts() if the app doesn't touch FP during the signal handler
execution.  This will stop generating a DNA, during the fxrstor in the
sigreturn.

This improves 64-bit lat_sig numbers by ~30% on my core2 platform.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

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Siddha, Suresh B 2007-11-11 11:27:59 -08:00 • committed by Linus Torvalds

parent efe44183f6

commit 92d140e21f

2 changed files with 10 additions and 4 deletions

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9

arch/x86/kernel/i387_64.c

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5

include/asm-x86/i387_64.h

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