From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 44859C43461 for ; Wed, 16 Sep 2020 09:06:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DD0B421D43 for ; Wed, 16 Sep 2020 09:06:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="fEezQmk/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726644AbgIPJGf (ORCPT ); Wed, 16 Sep 2020 05:06:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38438 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726149AbgIPJGa (ORCPT ); Wed, 16 Sep 2020 05:06:30 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81EFFC06174A for ; Wed, 16 Sep 2020 02:06:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=XGOGWszl2fZU1wbir3hgL3wXW46VrlHkuXhbLpO08Eo=; b=fEezQmk/8ai823rFebUytBjY5y IV44DUH8WhTUysiCTNpXhJu7FYGpDSlvp1wnKBDsHHQZ89iZcj4ZAg171aFSWMStaiuup8xI4Pyg6 o+zYu2SNH2eV6u02z81xgGNIpfKxuD01zNPq+wsziSg/vUxSXZN2NZLuLFNvFjXtqpAYLGM/pvkv3 qtqIKvHoohr9zqwH6nJQYm+ycf7H090vLu4oXnbPzBXH56+2HgSKbra1DpZ3JlEcUjiLTkHKAZWwl veIWBscVakesnjWOVUITVU+dwps9RZduAwty8pMPXNdfBipK+uk7A6RXQo20zZFpyKaEzBtQAyoSN n6uIFp7Q==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kITOP-0006oH-Lj; Wed, 16 Sep 2020 09:06:22 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 4050B3012DF; Wed, 16 Sep 2020 11:06:20 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3012A2149392C; Wed, 16 Sep 2020 11:06:20 +0200 (CEST) Date: Wed, 16 Sep 2020 11:06:20 +0200 From: peterz@infradead.org To: Marco Elver Cc: Josh Poimboeuf , Borislav Petkov , Nick Desaulniers , Rong Chen , kernel test robot , "Li, Philip" , x86-ml , LKML , clang-built-linux , Andrew Morton , Kees Cook , Masahiro Yamada , kasan-dev Subject: Re: [tip:x86/seves] BUILD SUCCESS WITH WARNING e6eb15c9ba3165698488ae5c34920eea20eaa38e Message-ID: <20200916090620.GN2674@hirez.programming.kicks-ass.net> References: <5f60c4e0.Ru0MTgSE9A7mqhpG%lkp@intel.com> <20200915135519.GJ14436@zn.tnic> <20200915141816.GC28738@shao2-debian> <20200915160554.GN14436@zn.tnic> <20200915170248.gcv54pvyckteyhk3@treble> <20200915172152.GR14436@zn.tnic> <20200916083032.GL2674@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 16, 2020 at 10:46:41AM +0200, Marco Elver wrote: > On Wed, 16 Sep 2020 at 10:30, wrote: > > On Tue, Sep 15, 2020 at 08:09:16PM +0200, Marco Elver wrote: > > > On Tue, 15 Sep 2020 at 19:40, Nick Desaulniers wrote: > > > > On Tue, Sep 15, 2020 at 10:21 AM Borislav Petkov wrote: > > > > > > > init/calibrate.o: warning: objtool: asan.module_ctor()+0xc: call without frame pointer save/setup > > > > > init/calibrate.o: warning: objtool: asan.module_dtor()+0xc: call without frame pointer save/setup > > > > > init/version.o: warning: objtool: asan.module_ctor()+0xc: call without frame pointer save/setup > > > > > init/version.o: warning: objtool: asan.module_dtor()+0xc: call without frame pointer save/setup > > > > > certs/system_keyring.o: warning: objtool: asan.module_ctor()+0xc: call without frame pointer save/setup > > > > > certs/system_keyring.o: warning: objtool: asan.module_dtor()+0xc: call without frame pointer save/setup > > > > > > This one also appears with Clang 11. This is new I think because we > > > started emitting ASAN ctors for globals redzone initialization. > > > > > > I think we really do not care about precise stack frames in these > > > compiler-generated functions. So, would it be reasonable to make > > > objtool ignore all *san.module_ctor and *san.module_dtor functions (we > > > have them for ASAN, TSAN, MSAN)? > > > > The thing is, if objtool cannot follow, it cannot generate ORC data and > > our unwinder cannot unwind through the instrumentation, and that is a > > fail. > > > > Or am I missing something here? > > They aren't about the actual instrumentation. The warnings are about > module_ctor/module_dtor functions which are compiler-generated, and > these are only called on initialization/destruction (dtors only for > modules I guess). > > E.g. for KASAN it's the calls to __asan_register_globals that are > called from asan.module_ctor. For KCSAN the tsan.module_ctor is > effectively a noop (because __tsan_init() is a noop), so it really > doesn't matter much. > > Is my assumption correct that the only effect would be if something > called by them fails, we just don't see the full stack trace? I think > we can live with that, there are only few central places that deal > with ctors/dtors (do_ctors(), ...?). Not only fails, lockdep for example likes to store stack traces of various callsites etc.. Also perf (NMI) likes to think it can unwind at all times. > The "real" fix would be to teach the compilers about "frame pointer > save/setup" for generated functions, but I don't think that's > realistic. How is that unrealistic? If you build with framepointers enabled, the compiler is supposed to know about this stuff.