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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 BF5F5C433DB for ; Wed, 17 Mar 2021 14:40:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7098364F7B for ; Wed, 17 Mar 2021 14:40:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231993AbhCQOkZ (ORCPT ); Wed, 17 Mar 2021 10:40:25 -0400 Received: from mx2.suse.de ([195.135.220.15]:37652 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232163AbhCQOkA (ORCPT ); Wed, 17 Mar 2021 10:40:00 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id ACA4FAD74; Wed, 17 Mar 2021 14:39:59 +0000 (UTC) Date: Wed, 17 Mar 2021 15:39:59 +0100 (CET) From: Miroslav Benes To: Peter Zijlstra cc: x86@kernel.org, jpoimboe@redhat.com, jgross@suse.com, linux-kernel@vger.kernel.org, samitolvanen@google.com Subject: Re: [PATCH 6/9] objtool: Add elf_create_undef_symbol() In-Reply-To: Message-ID: References: <20210312171613.533405394@infradead.org> <20210312171653.710872453@infradead.org> User-Agent: Alpine 2.21 (LSU 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 17 Mar 2021, Peter Zijlstra wrote: > On Wed, Mar 17, 2021 at 02:52:23PM +0100, Miroslav Benes wrote: > > > > + if (!elf_symbol_add(elf, sym, SHN_XINDEX)) { > > > + WARN("elf_symbol_add"); > > > + return NULL; > > > + } > > > > SHN_XINDEX means that the extended section index is used. Above you seem > > to use it in the opposite sense too (assigning to shndx when shndx_data is > > NULL). While it makes the code easier to handle, it is a bit confusing > > (and maybe I am just confused now). Could you add a comment about that, > > please? elf_symbol_add() seems like a good place. > > Yes, that was a horrible thing to do :/ And you understood it right. > > Looking at it again, I'm not sure it is actually correct tho; shouldn't > elf_create_undef_symbol() also look at gelf_getsymshndx() of symtab ? Probably yes. > What toolchain generates these extended sections and how? That is, how > do I test this crud.. Sami might know. Miroslav