From: Andi Kleen <ak@linux.intel.com>
Date: Fri, 16 Aug 2013 21:17:19 +0000 (-0700)
Subject: x86: Add 1/2/4/8 byte optimization to 64bit __copy_{from,to}_user_inatomic
X-Git-Tag: v3.2.81~40
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=733037c3c89b259235ff5217096b1c846fe7e6e2;p=pandora-kernel.git

x86: Add 1/2/4/8 byte optimization to 64bit __copy_{from,to}_user_inatomic

commit ff47ab4ff3cddfa7bc1b25b990e24abe2ae474ff upstream.

The 64bit __copy_{from,to}_user_inatomic always called
copy_from_user_generic, but skipped the special optimizations for 1/2/4/8
byte accesses.

This especially hurts the futex call, which accesses the 4 byte futex
user value with a complicated fast string operation in a function call,
instead of a single movl.

Use __copy_{from,to}_user for _inatomic instead to get the same
optimizations. The only problem was the might_fault() in those functions.
So move that to new wrapper and call __copy_{f,t}_user_nocheck()
from *_inatomic directly.

32bit already did this correctly by duplicating the code.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Link: http://lkml.kernel.org/r/1376687844-19857-2-git-send-email-andi@firstfloor.org
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: mingo@redhat.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: h.zuidam@computer.org
---

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