Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753100AbbGNV5U (ORCPT ); Tue, 14 Jul 2015 17:57:20 -0400 Received: from bombadil.infradead.org ([198.137.202.9]:36438 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751919AbbGNV5S (ORCPT ); Tue, 14 Jul 2015 17:57:18 -0400 Date: Tue, 14 Jul 2015 23:56:49 +0200 From: Peter Zijlstra To: Josh Poimboeuf Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Michal Marek , Andy Lutomirski , Borislav Petkov , Linus Torvalds , Andi Kleen , Pedro Alves , x86@kernel.org, live-patching@vger.kernel.org, linux-kernel@vger.kernel.org, Steven Rostedt Subject: Re: [PATCH v7 2/4] x86/stackvalidate: Compile-time stack validation Message-ID: <20150714215649.GQ19282@twins.programming.kicks-ass.net> References: <20150714210858.GP19282@twins.programming.kicks-ass.net> <20150714213034.GB13950@treble.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150714213034.GB13950@treble.redhat.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1304 Lines: 36 On Tue, Jul 14, 2015 at 04:30:34PM -0500, Josh Poimboeuf wrote: > > How (if it does at all) deal with function-trace / -pg -fprofile-arcs > > things? Does it silently ignore the __mcount calls and assumes ftrace > > knows wtf its doing? ;-) > > Adding Steven to CC to keep me honest. > > In the case of "-pg -mfentry", which is what ftrace has relied on for Ah -mfentry is the magic word, I couldn't find it and a grep led me astray. > the past few years for newer versions of gcc, stackvalidate silently > ignores __fentry__ calls and assumes that ftrace indeed knows wtf it's > doing. I don't see a problem there as long as the ftrace handler > doesn't sleep. They should not indeed, however it would be very nice if backtraces would still be 'good'. > I haven't run stackvalidate on the old "-pg" mcount non-fentry stuff, > but I think it creates a stack frame before calling mcount, so it should > be fine. Ok. > I don't know much about -fprofile-arcs, but as far as I can tell, it's > only used for gcov. Right, nobody much uses that I think. -- 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/