From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755807Ab1DVAKx (ORCPT ); Thu, 21 Apr 2011 20:10:53 -0400 Received: from shutemov.name ([188.40.19.243]:45460 "EHLO shutemov.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755735Ab1DVAKw (ORCPT ); Thu, 21 Apr 2011 20:10:52 -0400 Date: Fri, 22 Apr 2011 03:10:50 +0300 From: "Kirill A. Shutemov" To: Richard Weinberger Cc: linux-kernel@vger.kernel.org, user-mode-linux-devel@lists.sourceforge.net Subject: Re: [PATCH] um: Adjust current_thread_info() for gcc-4.6 Message-ID: <20110422001050.GA468@shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1302908593-4374-1-git-send-email-richard@nod.at> 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 On Sat, Apr 16, 2011 at 01:03:13AM +0200, Richard Weinberger wrote: > In some cases gcc-4.6 will optimize away current_thread_info(). > To prevent gcc from doing so the stack address has to be obtained > via inline asm. > > LKML-Reference: http://marc.info/?i=201104132150.05623.richard@nod.at > > Signed-off-by: Richard Weinberger Acked-by: Kirill A. Shutemov Also reproducible with gcc version 4.5.2 (Ubuntu/Linaro 4.5.2-8ubuntu4). > --- > arch/um/include/asm/thread_info.h | 5 ++++- > 1 files changed, 4 insertions(+), 1 deletions(-) > > diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h > index e2cf786..5bd1bad 100644 > --- a/arch/um/include/asm/thread_info.h > +++ b/arch/um/include/asm/thread_info.h > @@ -49,7 +49,10 @@ static inline struct thread_info *current_thread_info(void) > { > struct thread_info *ti; > unsigned long mask = THREAD_SIZE - 1; > - ti = (struct thread_info *) (((unsigned long) &ti) & ~mask); > + void *p; > + > + asm volatile ("" : "=r" (p) : "0" (&ti)); > + ti = (struct thread_info *) (((unsigned long)p) & ~mask); > return ti; > } > > -- > 1.6.6.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kirill A. Shutemov