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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 640B1C4332B for ; Thu, 19 Mar 2020 11:12:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 38C0D20724 for ; Thu, 19 Mar 2020 11:12:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="L7luK57b" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726947AbgCSLMp (ORCPT ); Thu, 19 Mar 2020 07:12:45 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:45238 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726188AbgCSLMp (ORCPT ); Thu, 19 Mar 2020 07:12:45 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=9stYWxdJp36g8rLWHqSWCUo3F2n7SRE1lKvnUXKPdz8=; b=L7luK57bfFJoO2hpPmPtU3WT7i 7lFS0PpKekYPt/w+iG/iEIhPcfrOMXSaY9brHULkiX/0DRm3zosA1gSi/1CJpytC7LAEuFFuzcNjv m6kc1tSc7LDtmBZN8IWhZmxSnOz/wZTFzOdGc87lx2/Z4iCFx5bjkw7FnyWbyB8ZiJB3bOustrB04 /1XFTDWc/YBKZ9GfYMwD8+edC1HcU0eygeIsSqjqxuYPvtyX1NMxIBas9lutafn3q2b0Dq1Zg+iFL H33sOEMPxfkySYaElBcWniBEhtf0LwUANcPPqoVuVR5qU8froBwOAsMegmp4BRzMg3Y6af/RELXXi 8CxD9pyg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jEt6N-0008SD-RC; Thu, 19 Mar 2020 11:12:39 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 3CE07300235; Thu, 19 Mar 2020 12:12:36 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CDE17286A8B7A; Thu, 19 Mar 2020 12:12:36 +0100 (CET) Date: Thu, 19 Mar 2020 12:12:36 +0100 From: Peter Zijlstra To: Josh Poimboeuf Cc: Randy Dunlap , Stephen Rothwell , Linux Next Mailing List , Linux Kernel Mailing List , Kees Cook , jakub@redhat.com, dvyukov@google.com Subject: Re: linux-next: Tree for Mar 18 (objtool) Message-ID: <20200319111236.GC20760@hirez.programming.kicks-ass.net> References: <20200318220920.48df2e76@canb.auug.org.au> <20200318182352.2dgwwl4ugbwndi4x@treble> <20200318200542.GK20730@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200318200542.GK20730@hirez.programming.kicks-ass.net> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 18, 2020 at 09:05:42PM +0100, Peter Zijlstra wrote: > On Wed, Mar 18, 2020 at 01:23:52PM -0500, Josh Poimboeuf wrote: > > 545ed6816b72 ("ubsan: add trap instrumentation option") > > > > Kees, any idea why that commit causes at least some BUG() statements to > > output an extra UD2? > > "Built-in Function: void __builtin_trap (void) > > This function causes the program to exit abnormally. GCC implements > this function by using a target-dependent mechanism (such as > intentionally executing an illegal instruction) or by calling abort. > The mechanism used may vary from release to release so you should > not rely on any particular implementation." > > Sounds encouraging :-( Kees, can you tell the GCC/LLVM folks that now you've used it in the kernel we have very definite expectations of the implementation. Them changing it is no longer an option.