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 65335C43381 for ; Tue, 26 Feb 2019 11:25:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 28C61206B8 for ; Tue, 26 Feb 2019 11:25:42 +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="RWUgnebv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728044AbfBZLZk (ORCPT ); Tue, 26 Feb 2019 06:25:40 -0500 Received: from merlin.infradead.org ([205.233.59.134]:50238 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726240AbfBZLZj (ORCPT ); Tue, 26 Feb 2019 06:25:39 -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=qLZDyuxEqHHZxgWif0G+gtirBnXXdyU1+gqVsC36lHE=; b=RWUgnebv7xFFCnS/jfw+vyjei kCtJlT1dwh8hPZylVMJOK9dHZmMdr30glrp2VaxLrzKbnB7lGWN9E8SuJ4Zs8gFTBepvxDD1tAwzQ hkjwqrWsZxRE9fqnQOJr1TYcKTa2SBUcVaJPU1umco+wj7nANMyjtQuu/zFTGaOeS8YV0nX7WVa+9 3G6s2rKIKQJ1ZGR2lmC1l01hpWQWLUP1xYLLgSrHFxJ43tuzJoBveILmmXfrHjYzow4RJdAzsdlTb yccXRXiT6SetUPXRkknY9BkUiNLzYGcci47QwwSIwqWZc4fuCZRGrgOCNSKnBn4lfEW5i9uDs5w9U fPLZtMGXg==; 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 1gyarT-00057q-FS; Tue, 26 Feb 2019 11:25:23 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 01E9B20269AFC; Tue, 26 Feb 2019 12:25:21 +0100 (CET) Date: Tue, 26 Feb 2019 12:25:21 +0100 From: Peter Zijlstra To: "Paul E. McKenney" Cc: 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 , Akira Yokosawa , Daniel Lustig Subject: Re: [RFC PATCH] tools/memory-model: Remove (dep ; rfi) from ppo Message-ID: <20190226112521.GH32534@hirez.programming.kicks-ass.net> References: <20190220020117.GD11787@linux.ibm.com> <20190220092604.GD32494@hirez.programming.kicks-ass.net> <20190220131456.GA3215@andrea> <20190220132714.GI32494@hirez.programming.kicks-ass.net> <20190222112128.GA7213@andrea> <20190222130014.GY32494@hirez.programming.kicks-ass.net> <20190225175517.GK4072@linux.ibm.com> <20190226093009.GS32477@hirez.programming.kicks-ass.net> <20190226104551.GF32534@hirez.programming.kicks-ass.net> <20190226112133.GG32534@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190226112133.GG32534@hirez.programming.kicks-ass.net> 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 Tue, Feb 26, 2019 at 12:21:33PM +0100, Peter Zijlstra wrote: > Also; we need to find a GCC person to find/give us a knob to kill this > entire class of nonsense. This is just horrible broken shit: > > > ~/tmp# gcc -O2 -fno-strict-aliasing -o ptr ptr.c ; ./ptr > p=0x5635dd3d5034 q=0x5635dd3d5034 > x=1 y=2 *p=11 *q=2 > ~/tmp# cat ptr.c > #include > #include > int y = 2, x = 1; > int main (int argc, char **argv) { > int *p = &x + argc; damn; wrong version; that should've been: s/argc/1/ same result though. > int *q = &y; > printf("p=%p q=%p\n", p, q); > if (!memcmp(&p, &q, sizeof(p))) { > *p = 11; > printf("x=%d y=%d *p=%d *q=%d\n", x, y, *p, *q); > } > }