linux-kernel - [GIT PULL] One more vdso fix for 3.19

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Date:	Tue, 23 Dec 2014 13:19:59 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>
Subject: [GIT PULL] One more vdso fix for 3.19

Hi Ingo et al,

Please consider pulling for x86/urgent.

Thanks,
Andy

The following changes since commit 394f56fe480140877304d342dec46d50dc823d46:

  x86_64, vdso: Fix the vdso address randomization algorithm
(2014-12-20 16:56:57 -0800)

are available in the git repository at:

  git://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git
tags/pr-20141223-x86-vdso

for you to fetch changes up to 1ddf0b1b11aa8a90cef6706e935fc31c75c406ba:

  x86, vdso: Use asm volatile in __getcpu (2014-12-23 13:05:30 -0800)

----------------------------------------------------------------
This is hopefully the last vdso fix for 3.19.  It should be very
safe (it just adds a volatile).

I don't think it fixes an actual bug (the __getcpu calls in the
pvclock code may not have been needed in the first place), but
discussion on that point is ongoing.

It also fixes a big performance issue in 3.18 and earlier in which
the lsl instructions in vclock_gettime got hoisted so far up the
function that they happened even when the function they were in was
never called.  n 3.19, the performance issue seems to be gone due to
the whims of my compiler and some interaction with a branch that's
now gone.

I'll hopefully have a much bigger overhaul of the pvclock code
for 3.20, but it needs careful review.

----------------------------------------------------------------
Andy Lutomirski (1):
      x86, vdso: Use asm volatile in __getcpu

 arch/x86/include/asm/vgtod.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
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