locking/x86: Add cc clobber for ADDL

ADDL clobbers flags (such as CF) but barrier.h didn't tell this
to GCC. Historically, GCC doesn't need one on x86, and always
considers flags clobbered. We are probably missing the cc
clobber in a *lot* of places for this reason.

But even if not necessary, it's probably a good thing to add for
documentation, and in case GCC semantcs ever change.

Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: virtualization <virtualization@lists.linux-foundation.org>
Link: http://lkml.kernel.org/r/1453921746-16178-2-git-send-email-mst@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Michael S. Tsirkin 2016-01-28 19:02:29 +02:00 • committed by Ingo Molnar
commit bd922477d9