Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933036Ab0AGJTQ (ORCPT ); Thu, 7 Jan 2010 04:19:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932948Ab0AGJTG (ORCPT ); Thu, 7 Jan 2010 04:19:06 -0500 Received: from mtagate2.de.ibm.com ([195.212.17.162]:58299 "EHLO mtagate2.de.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933014Ab0AGJS7 (ORCPT ); Thu, 7 Jan 2010 04:18:59 -0500 Date: Thu, 7 Jan 2010 10:18:55 +0100 From: Martin Schwidefsky To: Roland McGrath Cc: Oleg Nesterov , caiqian@redhat.com, Heiko Carstens , Jan Kratochvil , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, utrace-devel@redhat.com Subject: Re: s390 && user_enable_single_step() (Was: odd utrace testing results on s390x) Message-ID: <20100107101855.13248dc2@mschwide.boeblingen.de.ibm.com> In-Reply-To: <20100106211329.DB4F5134D@magilla.sf.frob.com> References: <20100104155225.GA16650@redhat.com> <20100104171626.22ea2d9c@mschwide.boeblingen.de.ibm.com> <20100104181412.GA21146@redhat.com> <20100104211147.4CC94D532@magilla.sf.frob.com> <20100105105030.66bb8a0a@mschwide.boeblingen.de.ibm.com> <20100105153633.GA9376@redhat.com> <20100105164610.388effd3@mschwide.boeblingen.de.ibm.com> <20100105155913.GA10652@redhat.com> <20100105170301.GA13641@redhat.com> <20100105195818.GA20358@redhat.com> <20100106201722.GB26204@redhat.com> <20100106211329.DB4F5134D@magilla.sf.frob.com> Organization: IBM Corporation X-Mailer: Claws Mail 3.7.3 (GTK+ 2.18.5; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1912 Lines: 49 On Wed, 6 Jan 2010 13:13:29 -0800 (PST) Roland McGrath wrote: > > However, with or without CONFIG_UTRACE, 6580807da14c423f0d0a708108e6df6ebc8bc83d > > is needed on s390 too, otherwise the child gets unnecessary traps. > > This confuses me. user_disable_single_step on non-current doesn't do > anything not already done by the memset in copy_thread. Ooh, except > perhaps it does not clear PSW_MASK_PER. Maybe that matters. That's > the only thing I can think of. Maybe Martin can make sense of it. The additional traps should not happen anymore with this patch: -- Subject: [PATCH] clear TIF_SINGLE_STEP for new process. From: Martin Schwidefsky Clear the TIF_SINGLE_STEP bit in copy_thread. If the new process is not auto-attached by the tracer it is wrong to delivere SIGTRAP to the new process. Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/process.c | 1 + 1 file changed, 1 insertion(+) diff -urpN linux-2.6/arch/s390/kernel/process.c linux-2.6-patched/arch/s390/kernel/process.c --- linux-2.6/arch/s390/kernel/process.c 2009-12-03 04:51:21.000000000 +0100 +++ linux-2.6-patched/arch/s390/kernel/process.c 2010-01-07 09:25:53.000000000 +0100 @@ -217,6 +217,7 @@ int copy_thread(unsigned long clone_flag p->thread.mm_segment = get_fs(); /* Don't copy debug registers */ memset(&p->thread.per_info, 0, sizeof(p->thread.per_info)); + clear_tsk_thread_flag(p, TIF_SINGLE_STEP); /* Initialize per thread user and system timer values */ ti = task_thread_info(p); ti->user_timer = 0; -- blue skies, Martin. "Reality continues to ruin my life." - Calvin. -- 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/