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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1DE84C433EF for ; Wed, 11 May 2022 16:24:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344713AbiEKQYp (ORCPT ); Wed, 11 May 2022 12:24:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36464 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235631AbiEKQYn (ORCPT ); Wed, 11 May 2022 12:24:43 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C6BC66A42E; Wed, 11 May 2022 09:24:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=GUx22QWRIdRq3isbQ/KOmjL53RGwGZCiPHsPEnUFiNI=; b=kf0KRlAqJk1zkf1t7YYHIeELIh qXIiW9yEkHC1o+CaK0S8ENApBE4oN8dxsWzgdyynYAb7VGhY/p9yPjG1Qn0yd9EqR2ZFmjlrCdHFc AAhqfaUowGtnHxyyYGg90iinjfBPyaCAaIzucLzXcYzymMgf3WbU5goEzmyD1uWdIS+pWCukmGvIs zYzpShYQaNsIuMZ/5kyjD6MgZBP6e2I7Gbj9KxHgTRqX6IdWPaFkGF7HBYHTPdODXskyD/TzBUr0n JknMKdpnCFnqqBlq4j2u8ASBBsXf3Fkbf0DEQh3VccO9fRBFwHFV+D7uNCUeBIcMbghBFpNHdJCDQ zFoSlyyA==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1nop8b-007mFo-Jb; Wed, 11 May 2022 16:24:33 +0000 Date: Wed, 11 May 2022 09:24:33 -0700 From: Luis Chamberlain To: Daniel Borkmann Cc: Alexei Starovoitov , Alexei Starovoitov , Song Liu , bpf , LKML , llvm@lists.linux.dev, Borislav Petkov Subject: Re: [PATCH] bpf.h: fix clang compiler warning with unpriv_ebpf_notify() Message-ID: References: <20220509203623.3856965-1-mcgrof@kernel.org> <3e3ed3d1-937b-a715-376d-43a8b7485f68@iogearbox.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3e3ed3d1-937b-a715-376d-43a8b7485f68@iogearbox.net> Sender: Luis Chamberlain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 11, 2022 at 06:17:26PM +0200, Daniel Borkmann wrote: > On 5/11/22 6:08 PM, Luis Chamberlain wrote: > > On Wed, May 11, 2022 at 09:03:13AM -0700, Alexei Starovoitov wrote: > > > On Wed, May 11, 2022 at 8:58 AM Luis Chamberlain wrote: > > > > On Mon, May 09, 2022 at 01:36:23PM -0700, Luis Chamberlain wrote: > > > > > The recent commit "bpf: Move BPF sysctls from kernel/sysctl.c to BPF core" > > > > > triggered 0-day to issue an email for what seems to have been an old > > > > > clang warning. So this issue should have existed before as well, from > > > > > what I can tell. The issue is that clang expects a forward declaration > > > > > for routines declared as weak while gcc does not. > > > > > > > > > > This can be reproduced with 0-day's x86_64-randconfig-c007 > > > > > https://download.01.org/0day-ci/archive/20220424/202204240008.JDntM9cU-lkp@intel.com/config > > > > > > > > > > And using: > > > > > > > > > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 ARCH=x86_64 SHELL=/bin/bash kernel/bpf/syscall.o > > > > > Compiler will be installed in /home/mcgrof/0day > > > > > make --keep-going HOSTCC=/home/mcgrof/0day/clang/bin/clang CC=/home/mcgrof/0day/clang/bin/clang LD=/home/mcgrof/0day/clang/bin/ld.lld HOSTLD=/home/mcgrof/0day/clang/bin/ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump OBJSIZE=llvm-size READELF=llvm-readelf HOSTCXX=clang++ HOSTAR=llvm-ar CROSS_COMPILE=x86_64-linux-gnu- --jobs=24 W=1 ARCH=x86_64 SHELL=/bin/bash kernel/bpf/syscall.o > > > > > DESCEND objtool > > > > > CALL scripts/atomic/check-atomics.sh > > > > > CALL scripts/checksyscalls.sh > > > > > CC kernel/bpf/syscall.o > > > > > kernel/bpf/syscall.c:4944:13: warning: no previous prototype for function 'unpriv_ebpf_notify' [-Wmissing-prototypes] > > > > > void __weak unpriv_ebpf_notify(int new_state) > > > > > ^ > > > > > kernel/bpf/syscall.c:4944:1: note: declare 'static' if the function is not intended to be used outside of this translation unit > > > > > void __weak unpriv_ebpf_notify(int new_state) > > > > > ^ > > > > > static > > > > > > > > > > Fixes: 2900005ea287 ("bpf: Move BPF sysctls from kernel/sysctl.c to BPF core") > > > > > Signed-off-by: Luis Chamberlain > > > > > --- > > > > > > > > > > Daniel, > > > > > > > > > > Given what we did fore 2900005ea287 ("bpf: Move BPF sysctls from > > > > > kernel/sysctl.c to BPF core") where I had pulled pr/bpf-sysctl a > > > > > while ago into sysctl-next and then merged the patch in question, > > > > > should I just safely carry this patch onto sysctl-next? Let me know > > > > > how you'd like to proceed. > > > > > > > > > > Also, it wasn't clear if putting this forward declaration on > > > > > bpf.h was your ideal preference. > > > > > > > > After testing this on sysctl-testing without issues going to move this > > > > to sysctl-next now. > > > > > > Hmm. No. > > > A similar patch should be in tip already. You have to wait > > > for it to go through Linus's tree and back to whatever tree you use. > > > > I'm a bit confused, the patch in question which my patch fixes should only > > be in my sysctl-next tree at this point, not in Linus's tree. > > Borislav was planning to route it via tip tree, maybe confusion was that the > fix in the link below is from Josh: > > https://lore.kernel.org/bpf/CAADnVQKjfQMG_zFf9F9P7m0UzqESs7XoRy=udqrDSodxa8yBpg@mail.gmail.com/ Ah, Josh posted a fix for the same compile warning. > But I presume this is routed as fix to Linus, so should land in both sysctl > and bpf tree at some point after re-sync. It may be the case indeed that the code in question was triggering a compile warning without the patch I have merged which moves the BPF sysctls ("bpf: Move BPF sysctls from kernel/sysctl.c to BPF core"). So I'll just drop my fix. Luis