Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753372AbbETJDb (ORCPT ); Wed, 20 May 2015 05:03:31 -0400 Received: from verein.lst.de ([213.95.11.211]:50629 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753183AbbETJD1 (ORCPT ); Wed, 20 May 2015 05:03:27 -0400 Date: Wed, 20 May 2015 11:03:25 +0200 From: Torsten Duwe To: Michael Ellerman Cc: Jiri Kosina , ppc-dev , Linux Kernel Mailing List Subject: Re: [PATCH] ppc64 ftrace: mark data_access callees "notrace" (pt.1) Message-ID: <20150520090325.GA11577@lst.de> References: <20150513161100.GA1619@lst.de> <1431653687.13498.1.camel@ellerman.id.au> <20150515084542.GA20453@suse.de> <20150516080534.GA27059@lst.de> <1432006027.8339.3.camel@ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1432006027.8339.3.camel@ellerman.id.au> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 841 Lines: 21 On Tue, May 19, 2015 at 01:27:07PM +1000, Michael Ellerman wrote: > On Mon, 2015-05-18 at 14:29 +0200, Jiri Kosina wrote: > > > > ftrace already handles recursion protection by itself (depending on the > > per-ftrace-ops FTRACE_OPS_FL_RECURSION_SAFE flag). > > OK, so I wonder why that's not working for us? IIRC a data access fault happens just before that flag is looked at ;-) I'm now thinking about a hybrid solution: mark the most critical functions "notrace", especially those directly involved with MMU loading, and add a per-thread flag to catch the not-so-obvious cases. Torsten -- 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/