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=-5.8 required=3.0 tests=BAYES_00,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 E1D0CC4361B for ; Thu, 17 Dec 2020 16:27:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AAF28239E5 for ; Thu, 17 Dec 2020 16:27:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728704AbgLQQ1A (ORCPT ); Thu, 17 Dec 2020 11:27:00 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:42207 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727303AbgLQQ07 (ORCPT ); Thu, 17 Dec 2020 11:26:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1608222333; 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=49yV2IcmGc0QJ5YAt0WJ2wci08ptQ85ppP+Sw3Lmdeo=; b=ZTVDeI627f0wePT787vrbctAs/GAT6huTw97akqO0vLx9xRQ2G2jxYKIywsBAWJma1X0bg XUNdC9imb4DevKtuOwcSVxqM1t1TyqYPnv5RP95iHrcOVLGJ3HIiXmGxzOIBhC3tQvL1uf 4Z/47/uMj9A0XEWdpnI1LiQx1zeFTAU= 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-487-qGT79G40PZycWtFdLMCbMg-1; Thu, 17 Dec 2020 11:25:31 -0500 X-MC-Unique: qGT79G40PZycWtFdLMCbMg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3E0B4803626; Thu, 17 Dec 2020 16:25:29 +0000 (UTC) Received: from treble (ovpn-112-170.rdu2.redhat.com [10.10.112.170]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A94895D9CD; Thu, 17 Dec 2020 16:25:28 +0000 (UTC) Date: Thu, 17 Dec 2020 10:25:24 -0600 From: Josh Poimboeuf To: Peter Zijlstra Cc: Linus Torvalds , linux-kernel@vger.kernel.org Subject: Re: New objtool warning.. Message-ID: <20201217162524.fkxiemn7aezpv7d5@treble> References: <20201216044918.jdmi32dz75uboybv@treble> <20201216200158.akf356yrw44o2rlb@treble> <20201217104556.GT3040@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20201217104556.GT3040@hirez.programming.kicks-ass.net> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 17, 2020 at 11:45:56AM +0100, Peter Zijlstra wrote: > On Wed, Dec 16, 2020 at 02:01:58PM -0600, Josh Poimboeuf wrote: > > So this is kind of tricky, because the unreachable() annotation usually > > means "the previous instruction is a dead end". Most of the time, the > > next instruction -- the one actually pointed to by the annotation -- is > > actually reachable from another path. > > *groan*, this is why I ended up sticking a nop in > instrumentation_begin()/_end(). Oh yeah, I forgot about that. That would be another option if my patch doesn't work out. /me grumbles something about integrating objtool with compiler plugins someday... -- Josh