From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S942785AbcJZNSP (ORCPT ); Wed, 26 Oct 2016 09:18:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44270 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941748AbcJZNSL (ORCPT ); Wed, 26 Oct 2016 09:18:11 -0400 Date: Wed, 26 Oct 2016 08:18:08 -0500 From: Josh Poimboeuf To: Arnd Bergmann Cc: Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] objtool: a couple of minor fixes Message-ID: <20161026131808.aqkxounmvfzikxqw@treble> References: <3971280.DNU2zoGODW@wuerfel> <20161026123739.6ih5hkgs3stdumkn@treble> <20161026124341.2snbgaa52n5fyrn3@treble> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20161026124341.2snbgaa52n5fyrn3@treble> User-Agent: Mutt/1.6.0.1 (2016-04-01) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 26 Oct 2016 13:18:09 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 26, 2016 at 07:43:41AM -0500, Josh Poimboeuf wrote: > On Wed, Oct 26, 2016 at 07:37:39AM -0500, Josh Poimboeuf wrote: > > On Wed, Oct 26, 2016 at 09:58:29AM +0200, Arnd Bergmann wrote: > > > On Thursday, October 13, 2016 4:22:51 PM CEST Josh Poimboeuf wrote: > > > > Fix a couple of issues: > > > > > > > > - fix a false positive warning related to switch statement jump tables > > > > - get rid of useless "unreachable instruction" warnings for gcov kernels > > > > > > > > Josh Poimboeuf (2): > > > > objtool: improve rare switch jump table pattern detection > > > > objtool: skip all "unreachable instruction" warnings for gcov kernels > > > > > > > > tools/objtool/builtin-check.c | 68 ++++++++++++++++++++++--------------------- > > > > 1 file changed, 35 insertions(+), 33 deletions(-) > > > > > > I got another warning today with linux-next, but have not looked into it: > > > > > > drivers/infiniband/sw/rxe/rxe_comp.o: warning: objtool: rxe_completer()+0x315: sibling call from callable instruction with changed frame pointer > > > > > > .config and object file attached. > > > > I think this is the same as one of the warnings you reported before (for > > which I opened the gcc bug): > > > > https://lkml.kernel.org/r/1855683.1QnG4Fe4Hq@wuerfel > > Er, scratch that. Actually this is similar to one I supposedly fixed > with commit 3732710ff6f2ce2b1b7f044937a422b717d4f953. And the other > warning looks similar. Will take a look. As it turns out, this one is a simple fix to the above mentioned commit. But as for the other warning... the code generation is just crazy. It's another issue with switch statement jump tables, which as it turns out are really hard to detect. I may ask the gcc folks for help. If they could mark the jump tables somehow, like maybe associating them with ELF symbols, it would make objtool's life (and mine!) so much easier. -- Josh