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 8D226C43334 for ; Mon, 25 Jul 2022 11:50:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231714AbiGYLuG (ORCPT ); Mon, 25 Jul 2022 07:50:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44440 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230032AbiGYLuF (ORCPT ); Mon, 25 Jul 2022 07:50:05 -0400 Received: from smtp-relay-canonical-0.canonical.com (smtp-relay-canonical-0.canonical.com [185.125.188.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0FF3DF4A; Mon, 25 Jul 2022 04:50:04 -0700 (PDT) Received: from quatroqueijos (1.general.cascardo.us.vpn [10.172.70.58]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-0.canonical.com (Postfix) with ESMTPSA id 0C31D3F11C; Mon, 25 Jul 2022 11:49:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1658749802; bh=azjCJStYinlUJkGMIRNeZrFjUm/sCt/hfpBDbAEn+tQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:In-Reply-To; b=eKDHv04jEAYFHhgugB5OGbPXzYU8hXVTUZzwQUZMuKH6Ik4JJPlj6pBYSCu3CcZGC NKTSpjgl+g8qKa9ir3t0/lG7GikRSRYc/F9arW61g6ZCSBRhFPEOg9c6BtrzlGx+pV W5xzFEPouViUrJNdd5eyjovPVb9e/jUr4LxtsKMeTS37P1bzO73OUlNtX9wznzKVDf G+pR9HJ9uQIBUU4YC23NPGBpqEExLezNTPiss4PqRMiRQmJVV9nG5ndSCoSsf3rz7n ae8Ohbpj8yyFcbXeh1JfO2yBb33u3Q8vDThsa0755EIwtv2nWYRrU+1Z2LqkOSs3xo DDp+8ARn5CehQ== Date: Mon, 25 Jul 2022 08:49:56 -0300 From: Thadeu Lima de Souza Cascardo To: Jiri Slaby Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, Josh Poimboeuf , Peter Zijlstra , Borislav Petkov Subject: Re: [PATCH 5.18 13/70] objtool: skip non-text sections when adding return-thunk sites Message-ID: References: <20220722090650.665513668@linuxfoundation.org> <20220722090651.464856922@linuxfoundation.org> <8a4f10b1-70b3-25fe-9ffc-4f24a1531139@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8a4f10b1-70b3-25fe-9ffc-4f24a1531139@kernel.org> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Mon, Jul 25, 2022 at 07:44:08AM +0200, Jiri Slaby wrote: > Hi, > > I wonder, why this is needed in stable and not mainline? > > Isn't this a different (non-upstream) dup of > 951ddecf4356 objtool: Treat .text.__x86.* as noinstr > ? (That is included in this release too.) > That's because RESERVE_BRK adds a function to .discard.text before upstream commit a1e2c031ec3949b8c039b739c0b5bf9c30007b00 ("x86/mm: Simplify RESERVE_BRK()"). Picking up that commit alone was frowned upon because it caused some problems that were still under investigation. Cascardo. > On 22. 07. 22, 11:07, Greg Kroah-Hartman wrote: > > From: Thadeu Lima de Souza Cascardo > > > > The .discard.text section is added in order to reserve BRK, with a > > temporary function just so it can give it a size. This adds a relocation to > > the return thunk, which objtool will add to the .return_sites section. > > Linking will then fail as there are references to the .discard.text > > section. > > > > Do not add instructions from non-text sections to the list of return thunk > > calls, avoiding the reference to .discard.text. > > > > Signed-off-by: Thadeu Lima de Souza Cascardo > > Acked-by: Josh Poimboeuf > > Signed-off-by: Greg Kroah-Hartman > > --- > > tools/objtool/check.c | 4 +++- > > 1 file changed, 3 insertions(+), 1 deletion(-) > > > > --- a/tools/objtool/check.c > > +++ b/tools/objtool/check.c > > @@ -1308,7 +1308,9 @@ static void add_return_call(struct objto > > insn->type = INSN_RETURN; > > insn->retpoline_safe = true; > > - list_add_tail(&insn->call_node, &file->return_thunk_list); > > + /* Skip the non-text sections, specially .discard ones */ > > + if (insn->sec->text) > > + list_add_tail(&insn->call_node, &file->return_thunk_list); > > } > > static bool same_function(struct instruction *insn1, struct instruction *insn2) > > > > > > thanks, > -- > js > suse labs