From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756520Ab3K0OU5 (ORCPT ); Wed, 27 Nov 2013 09:20:57 -0500 Received: from nat28.tlf.novell.com ([130.57.49.28]:33828 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751732Ab3K0OUz convert rfc822-to-8bit (ORCPT ); Wed, 27 Nov 2013 09:20:55 -0500 Message-Id: <52960DD202000078001079D8@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.2 Date: Wed, 27 Nov 2013 14:20:50 +0000 From: "Jan Beulich" To: "Ingo Molnar" Cc: , , "Linus Torvalds" , , , , Subject: Re: [PATCH] x86: override __compiletime_object_size() 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> <20131127140332.GC24403@gmail.com> In-Reply-To: <20131127140332.GC24403@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >>> On 27.11.13 at 15:03, Ingo Molnar wrote: > * 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. That makes no sense to me - the benefits of this construct should have been explained with its introduction; the change here just makes it being used under wider range of compilers (and the code comment already says exactly that). Jan