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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 419D0C1975A for ; Wed, 25 Mar 2020 14:42:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1602A2166E for ; Wed, 25 Mar 2020 14:42:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="hvfrPeq4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727768AbgCYOmX (ORCPT ); Wed, 25 Mar 2020 10:42:23 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:48123 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727123AbgCYOmW (ORCPT ); Wed, 25 Mar 2020 10:42:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585147341; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=f0QoE/qndgvHkzTsiprhqXEFUL5AmxJl7pgoSBh+XjM=; b=hvfrPeq4KmAm+Cs+gb+IfgeE/LP1KsgV18F4eXD7KaMzpn34cNds/eiasiSFJMO6CrItQe p1Ys5PISfcM2A+Y6iWE7LPloHhlFJv5c6GAbgl/mjgGfp/bc8jSrkdnu6t4ZKCk6ju24Px rwV1Ky9WSYumZ8oiPkdVxXiKGUNi0j0= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-163-3heDe8q8OI-tXT8rSVc0iQ-1; Wed, 25 Mar 2020 10:42:16 -0400 X-MC-Unique: 3heDe8q8OI-tXT8rSVc0iQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id DD080800D54; Wed, 25 Mar 2020 14:42:14 +0000 (UTC) Received: from treble (unknown [10.10.119.253]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BBCEA10002A5; Wed, 25 Mar 2020 14:42:13 +0000 (UTC) Date: Wed, 25 Mar 2020 09:42:11 -0500 From: Josh Poimboeuf To: Peter Zijlstra Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, x86@kernel.org, mhiramat@kernel.org, mbenes@suse.cz, brgerst@gmail.com Subject: Re: [PATCH v3 26/26] objtool: Add STT_NOTYPE noinstr validation Message-ID: <20200325144211.irnwnly37fyhapvx@treble> References: <20200324153113.098167666@infradead.org> <20200324160925.470421121@infradead.org> <20200324221616.2tdljgyay37aiw2t@treble> <20200324223455.GV2452@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200324223455.GV2452@worktop.programming.kicks-ass.net> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 24, 2020 at 11:34:55PM +0100, Peter Zijlstra wrote: > On Tue, Mar 24, 2020 at 05:16:16PM -0500, Josh Poimboeuf wrote: > > On Tue, Mar 24, 2020 at 04:31:39PM +0100, Peter Zijlstra wrote: > > > > + if (state.noinstr) { > > > + /* > > > + * In vmlinux mode we will not run validate_unwind_hints() by > > > + * default which means we'll not otherwise visit STT_NOTYPE > > > + * symbols. > > > + * > > > + * In case of --duplicate mode, insn->visited will avoid actual > > > + * duplicate work being done. > > > + */ > > > + list_for_each_entry(func, &sec->symbol_list, list) { > > > + if (func->type != STT_NOTYPE) > > > + continue; > > > + > > > + warnings += validate_symbol(file, sec, func, &state); > > > + } > > > + } > > > + > > > > I guess this is ok, but is there a valid reason why we don't just call > > validate_unwind_hints()? > > > > It's also slightly concerning that validate_reachable_instructions() > > isn't called, I'm not 100% convinced all the code will get checked. > > This will only end up running on .noinstr.text, while > validate_unwind_hints() will run on *everything*. That is, we're > purposely not checking everything. > > It very much relies on the !vmlinux mode to do the unreachable things. Sure, but couldn't validate_unwind_hints() and validate_reachable_instructions() be changed to *only* run on .noinstr.text, for the vmlinux case? That might help converge the vmlinux and !vmlinux paths. -- Josh