From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752919AbbJGK7E (ORCPT ); Wed, 7 Oct 2015 06:59:04 -0400 Received: from mail.skyhub.de ([78.46.96.112]:52687 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751896AbbJGK7B (ORCPT ); Wed, 7 Oct 2015 06:59:01 -0400 Date: Wed, 7 Oct 2015 12:59:34 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Brian Gerst , Denys Vlasenko , Linus Torvalds Subject: Re: [PATCH v2 02/36] x86/uaccess: __chk_range_not_ok is unlikely to return true Message-ID: <20151007105934.GB5046@nazgul.tnic> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 05, 2015 at 05:47:50PM -0700, Andy Lutomirski wrote: > This should improve code quality a bit. It also shrinks the kernel > text. > > Before: > text data bss dec hex filename > 21828379 5194760 1277952 28301091 1afd723 vmlinux > text data bss dec hex filename > 21827997 5194760 1277952 28300709 1afd5a5 vmlinux > > Signed-off-by: Andy Lutomirski > --- > arch/x86/include/asm/uaccess.h | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h > index 3e911c68876e..09b1b0ab94b7 100644 > --- a/arch/x86/include/asm/uaccess.h > +++ b/arch/x86/include/asm/uaccess.h > @@ -51,13 +51,13 @@ static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, un > * limit, not add it to the address). > */ > if (__builtin_constant_p(size)) > - return addr > limit - size; > + return unlikely(addr > limit - size); > > /* Arbitrary sizes? Be careful about overflow */ > addr += size; > - if (addr < size) > + if (unlikely(addr < size)) > return true; > - return addr > limit; > + return unlikely(addr > limit); It certainly uglifies it though. Are the wins worth the (un-)readability hit? -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. --