From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756868AbZBKOUU (ORCPT ); Wed, 11 Feb 2009 09:20:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753254AbZBKOUF (ORCPT ); Wed, 11 Feb 2009 09:20:05 -0500 Received: from hera.kernel.org ([140.211.167.34]:59736 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755237AbZBKOUD (ORCPT ); Wed, 11 Feb 2009 09:20:03 -0500 Message-ID: <4992DE69.4020205@kernel.org> Date: Wed, 11 Feb 2009 23:19:21 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.19 (X11/20081227) MIME-Version: 1.0 To: Ingo Molnar CC: hpa@zytor.com, jeremy@goop.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, x86@kernel.org, rusty@rustcorp.com.au Subject: Re: [PATCH] stackprotector: fix multi-word cross-builds References: <1234186798-16820-1-git-send-email-tj@kernel.org> <20090209135557.GB14785@elte.hu> <20090209141209.GA24323@elte.hu> <499186FB.4070506@kernel.org> <49918C3C.8030208@kernel.org> <20090210142026.GD16147@elte.hu> <49918E86.4020304@kernel.org> <20090211105729.GO20518@elte.hu> <20090211111846.GA22772@elte.hu> In-Reply-To: <20090211111846.GA22772@elte.hu> X-Enigmail-Version: 0.95.7 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.0 (hera.kernel.org [127.0.0.1]); Wed, 11 Feb 2009 14:19:36 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > * Ingo Molnar wrote: > >> * Tejun Heo wrote: >> >>> Ingo Molnar wrote: >>>>>> I'll try other compilers but which version are you using? The >>>>>> difference is that before the patchset, -fno-stack-protector was >>>>>> always added whether stackprotector was enabled or not so this problem >>>>>> wasn't visible (at the cost of bogus stackprotector of course). We'll >>>>>> probably need to add __stack_chk_guard or disable if gcc generates >>>>>> such symbol. I'll play with different gccs. >>>>> Can't reproduce with gcc-4.1 or 4.2. Any chance you're using distcc >>>>> w/ a build machine w/ glibc < 2.4? __stack_chk_guard is the symbol >>>>> gcc fetches stack canary from if TLS is not supported, so somehow gcc >>>>> thought that TLS wasn't available while building head64. >>>> yeah - i also used distcc. Maybe the nostackp makefile magic gets confused >>>> about that? >>> It seems that even with the same gcc versions, gcc built against libc >>> w/o TLS support generates __stack_chk_guard, so if you mix the two >>> flavors, the has-stack-protector check can be compiled on machines w/ >>> TLS while some other files end up being built on machines w/o TLS >>> support thus circumventing the support check. Can you please see >>> whether non-distcc build fails too? >> That build succeeds: >> >> rhea:~/tip> make -j30 bzImage ARCH=x86_64 CROSS_COMPILE='/opt/crosstool/gcc-4.2.3-glibc-2.3.6/x86_64-unknown-linux-gnu/bin/x86_64-unknown-linux-gnu-' >> /home/mingo/tip/arch/x86/Makefile:82: stack protector enabled but no compiler support >> CHK include/linux/version.h >> [...] >> BFD: arch/x86/boot/compressed/vmlinux.bin: warning: allocated section `.bss' not in segment >> [...] >> Root device is (8, 3) >> Setup is 11996 bytes (padded to 12288 bytes). >> System is 5690 kB >> CRC be1b2e21 >> Kernel: arch/x86/boot/bzImage is ready (#3) >> >> Some shell variable expansion bug? If CROSS_COMPILE is not a single word >> we fail to detect the compiler borkage at arch/x86/Makefile line 82? > > Yep - i'm testing the fix below now - it's looking good so far. Ah... okay. No wonder I couldn't reproduce the problem. :-) Thanks for hunting it down. -- tejun