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=-0.8 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,URIBL_BLOCKED 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 C8B73C4724C for ; Fri, 1 May 2020 17:50:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B41E20857 for ; Fri, 1 May 2020 17:50:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="TntHSw7X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730122AbgEARuc (ORCPT ); Fri, 1 May 2020 13:50:32 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:53633 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729393AbgEARub (ORCPT ); Fri, 1 May 2020 13:50:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588355429; 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=ucsSzBpiK2ssiDfbxZQQI4SWzJTSeJKTe65zvN75TBE=; b=TntHSw7X46jcYNQVw/VACPmckN+RqKvUvmirs34AeZGDFw9uF9GuPyzCljJnJRV3i8wCVu 6PupF0u30afATKEIc8BQQqjTsgV5cCrpB3AvrN2BktgXcMo2wmU8joMDuI80KVKRXY5+z4 e+s44Rcn75fyjECILeZHclTkAw1gGhs= 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-431-GTX5sAw_MO-B9Pq1twleUg-1; Fri, 01 May 2020 13:50:26 -0400 X-MC-Unique: GTX5sAw_MO-B9Pq1twleUg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0EEED108BD16; Fri, 1 May 2020 17:50:25 +0000 (UTC) Received: from treble (ovpn-114-104.rdu2.redhat.com [10.10.114.104]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 636845EE10; Fri, 1 May 2020 17:50:24 +0000 (UTC) Date: Fri, 1 May 2020 12:50:22 -0500 From: Josh Poimboeuf To: Peter Zijlstra Cc: Arnd Bergmann , the arch/x86 maintainers , Linux Kernel Mailing List Subject: Re: Remaining randconfig objtool warnings, linux-next-20200428 Message-ID: <20200501175022.yf3a34lu3ufui5ag@treble> References: <20200501172616.GG3762@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200501172616.GG3762@hirez.programming.kicks-ass.net> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 01, 2020 at 07:26:16PM +0200, Peter Zijlstra wrote: > On Fri, May 01, 2020 at 07:21:31PM +0200, Arnd Bergmann wrote: > > On Thu, Apr 30, 2020 at 4:05 PM Arnd Bergmann wrote: > > it gets into undefined behavior and stops emitting code after the call to > > > Do we consider this expected behavior on gcc's side, or is it something > > that should not happen and needs a gcc bug report? > > When it hits UB it is of course free to do whatever it damn well > pleases, but just stopping code gen seems a little extreme, at least > issue a WARN that something is up or so. > > Not sure how the GCC folks feel about this though. When we've seen truncated code flow like this in the past, it's either been a code bug (undefined behavior) or a GCC bug. So this is new. Is it only seen with GCC_PLUGIN_SANCOV enabled? Maybe (hopefully) it's an issue with the plugin and how it interacts with GCC 10. -- Josh