From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754526Ab3K0ODn (ORCPT ); Wed, 27 Nov 2013 09:03:43 -0500 Received: from mail-bk0-f41.google.com ([209.85.214.41]:39910 "EHLO mail-bk0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751428Ab3K0ODk (ORCPT ); Wed, 27 Nov 2013 09:03:40 -0500 Date: Wed, 27 Nov 2013 15:03:32 +0100 From: Ingo Molnar To: Jan Beulich Cc: mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, arjan@linux.intel.com, linux@roeck-us.net, linux-kernel@vger.kernel.org, Linus Torvalds Subject: Re: [PATCH] x86: override __compiletime_object_size() Message-ID: <20131127140332.GC24403@gmail.com> References: <5265056D02000078000FC4F3@nat28.tlf.novell.com> <20131026103109.GC14949@gmail.com> <526F914A02000078000FD806@nat28.tlf.novell.com> <20131029095408.GB25306@gmail.com> <526F971F02000078000FD841@nat28.tlf.novell.com> <20131029101257.GA25953@gmail.com> <529385AF0200007800106C84@nat28.tlf.novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <529385AF0200007800106C84@nat28.tlf.novell.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jan Beulich wrote: > As discussed in the context of commits 3df7b41a ("x86: Unify > copy_from_user() size checking") and 7a3d9b0f ("x86: Unify > copy_to_user() and add size checking to it"), we want to leverage > __builtin_object_size() also on newer gcc versions, but with other > architectures still using another model of copy_*_user() verification > we can't replace the global definition. Do it in the (only) header > needing the construct for now. > > Signed-off-by: Jan Beulich > Cc: Arjan van de Ven > Cc: Guenter Roeck > --- > arch/x86/include/asm/uaccess.h | 6 ++++++ > 1 file changed, 6 insertions(+) > > --- 3.13-rc1/arch/x86/include/asm/uaccess.h > +++ 3.13-rc1-x86-compiletime-object-size/arch/x86/include/asm/uaccess.h > @@ -584,6 +584,12 @@ __copy_from_user_overflow(int size, unsi > > #endif > > +/* linux/compiler-gcc4.h restricts this to gcc < 4.6, which doesn't suit us. */ > +#if defined(__GNUC__) && GCC_VERSION >= 40100 > +# undef __compiletime_object_size > +# define __compiletime_object_size(obj) __builtin_object_size(obj, 0) > +#endif > + Would be nice to have a more verbose changelog that explains what benefits this brings us. Thanks, Ingo