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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 6787EC43381 for ; Wed, 6 Mar 2019 16:58:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32CFC20684 for ; Wed, 6 Mar 2019 16:58:56 +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="xv0M1+nr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730199AbfCFQ6z (ORCPT ); Wed, 6 Mar 2019 11:58:55 -0500 Received: from merlin.infradead.org ([205.233.59.134]:44804 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726419AbfCFQ6y (ORCPT ); Wed, 6 Mar 2019 11:58:54 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Daoa5W1kY+eBrvLFATCAUtuqAOrV6WLhDnSOpJs+YPI=; b=xv0M1+nrrSu7k5Mo05NVEgL9/ kT4xFZ3Ep3V9S/xn5mAvELAbckbjcru/R5AFSzl0bXygAZz3kFVEuZmlAOIxtXAhnzbmMtkUP0W6Y Q1yYaB4ZJnRWbfTgmyy2c6YE0YmRnVHftnIeXkuizSb4ne/Tg46aLB58/SHLhqxkINJatgwJ2MJrP bxbplBS6y9k7VdcyvvewGtWf9iKV9W+ofBPhe7hFFvZURE4KCg6oNXF+qgWMyeZsv1o+M4ITmLtxV Vxe58KN3NYoszX/Au4CAcly9TtB6X3F7KPS4dxSpVrnpccPDN9LawNqWfYmqnKdgS72AU6f74HOwU kTDWe01+w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1h1ZsG-0004Av-Lm; Wed, 06 Mar 2019 16:58:32 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7263B20316505; Wed, 6 Mar 2019 17:58:31 +0100 (CET) Date: Wed, 6 Mar 2019 17:58:31 +0100 From: Peter Zijlstra To: Akira Yokosawa Cc: "Paul E. McKenney" , Borislav Petkov , Andrea Parri , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Alan Stern , Will Deacon , Boqun Feng , Nicholas Piggin , David Howells , Jade Alglave , Luc Maranget , Daniel Lustig Subject: Re: [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo Message-ID: <20190306165831.GZ32477@hirez.programming.kicks-ass.net> References: <20190226093009.GS32477@hirez.programming.kicks-ass.net> <20190226104551.GF32534@hirez.programming.kicks-ass.net> <20190226112133.GG32534@hirez.programming.kicks-ass.net> <20190226112521.GH32534@hirez.programming.kicks-ass.net> <20190226113008.GI32534@hirez.programming.kicks-ass.net> <20190226113813.GA14753@zn.tnic> <20190226134906.GG32494@hirez.programming.kicks-ass.net> <20190226142845.GK4072@linux.ibm.com> <20190226150450.GW32477@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 07, 2019 at 12:46:05AM +0900, Akira Yokosawa wrote: > So, I'm looking at the macro RELOC_HIDE() defined in include/linux/compiler-gcc.h. > Am I the only one who was not aware of this gcc-specific macro? It's one I regularly see, but had forgotten about in this context. However; you can also fix things by adding asm volatile ("":::"memory"); in places. But that's not really the point; I would really rather have a cmdline knob to fix things. That way we can compile the kernel with and without and look for differences. -fno-unicorns or something :-) While I understand some compiler people revel in UB and love to make unicorns happen, I think in this case the produces result is utterly insane.