Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760519AbYBWHiZ (ORCPT ); Sat, 23 Feb 2008 02:38:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754165AbYBWHiL (ORCPT ); Sat, 23 Feb 2008 02:38:11 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:38812 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757335AbYBWHiJ (ORCPT ); Sat, 23 Feb 2008 02:38:09 -0500 Date: Sat, 23 Feb 2008 08:37:46 +0100 From: Ingo Molnar To: James Morris Cc: Sam Ravnborg , Linus Torvalds , linux-kernel@vger.kernel.org, Arjan van de Ven , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" Subject: Re: Regression [Was: Boot hang with stack protector on x86_64] Message-ID: <20080223073746.GA28310@elte.hu> References: <20080222075950.GB2660@uranus.ravnborg.org> <20080222093621.GG327@elte.hu> <20080222121751.GA17889@elte.hu> <20080223061856.GA26185@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080223061856.GA26185@elte.hu> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2068 Lines: 55 * Ingo Molnar wrote: > could you try the fix below ontop of x86.git#testing, does it solve > your boot hang? find below another fix that is somewhat better as it does not affect the native kernel and !PARAVIRT. btw., this also explains why this bug wasnt reported sooner against x86.git#testing: people done normally use PARAVIRT on 64-bit yet. (there is no 64-bit host support) Ingo ----------------> Subject: x86: stackprotector & PARAVIRT fix From: Ingo Molnar Date: Sat Feb 23 07:06:55 CET 2008 on paravirt enabled 64-bit kernels the paravirt ops do function calls themselves - which is bad with the stackprotector - for example pda_init() loads 0 into %gs and then does MSR_GS_BASE write (which modifies gs.base) - but that MSR write is a function call on paravirt, which with stackprotector tries to read the stack canary from the PDA ... crashing the bootup. the solution was suggested by Arjan van de Ven: to exclude paravirt.c from stackprotector, too many lowlevel functionality is in it. It's not like we'll have paravirt functions with character arrays on their stack anyway... Signed-off-by: Arjan van de Ven Signed-off-by: Ingo Molnar --- arch/x86/kernel/Makefile | 1 + 1 file changed, 1 insertion(+) Index: linux-x86.q/arch/x86/kernel/Makefile =================================================================== --- linux-x86.q.orig/arch/x86/kernel/Makefile +++ linux-x86.q/arch/x86/kernel/Makefile @@ -15,6 +15,7 @@ nostackp := $(call cc-option, -fno-stack CFLAGS_vsyscall_64.o := $(PROFILING) -g0 $(nostackp) CFLAGS_hpet.o := $(nostackp) CFLAGS_tsc_64.o := $(nostackp) +CFLAGS_paravirt.o := $(nostackp) obj-y := process_$(BITS).o signal_$(BITS).o entry_$(BITS).o obj-y += traps_$(BITS).o irq_$(BITS).o -- 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/