Received: by 2002:ac0:a594:0:0:0:0:0 with SMTP id m20-v6csp208984imm; Tue, 15 May 2018 00:02:34 -0700 (PDT) X-Google-Smtp-Source: AB8JxZr3+09O6F4G5yTJw5Kv66apO6dlv1CWIUgBNGnvP7JBYnaTYZwK4PJCWEDZx1m9WV/yNdRm X-Received: by 2002:a65:4acc:: with SMTP id c12-v6mr11022082pgu.329.1526367754679; Tue, 15 May 2018 00:02:34 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1526367754; cv=none; d=google.com; s=arc-20160816; b=CUG9ZFIlTkeZ8v0LwLGD/ZdXbUkxu3wcdQLR17CiBYdeUrewIlnecCNftQUNfB03Cp Dx1xLchqRCROshAZheXj8GnhU1n7LxTAVaWGCVF7KGeXkUiR2w7mMTFhxZMcIw7QtqaX WMbo5ds1JZCUmLUAR8KNbh64+KpSS+XnQE7+Asjnre8if1OPOwRuK0ihpCX+TPgZEBW2 YpTBYzuoCKJ6R4jT98g+qSvX5/jUaPq5ZSgmG619JXd2YhIY9TWDNo281QE9fSitg5/I FKtDCrWn6ufpoNns5v2ur8J5HEFB3Mlb04ohh69+YUAI99CndIaTgCllMlfNIFnRz05Q UhEg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:message-id:from:cc:to:subject :content-transfer-encoding:mime-version:references:in-reply-to :user-agent:date:arc-authentication-results; bh=utLYfKQ64RGjoHD/JHW4llGQChzFXBmqUhTPuXlLWhs=; b=OEUyELYqUeuAYJtYIjkmsciIBliFfKjy4Ba9/HgdUy13EPlRZowRvcEtJGXfzGrIFH v0MxF4gXxWTWzHCBQLsoiEozOSnU+rg7OYLJdz68sgu/7IqpvK2GV9Zi+Cy3yzuFGBdS wXBdtljiLScz1MwFb459A+myQLM8tyIUGvUERPw86EIswGNRFN+XEo2oj73+K/tHcFNj JjwHC271HwXSCCpI83VhcvOsDG1PiORQsLpOSYtNWOTaCXGviRE5mijiknRUXEnQ0WUo O4tW6PWG4snL7VFOOFgGYwFAJhymfsWb7nwcqm0n31pEsm6qJJhb218F1HNzaqi2/oK1 RmCA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id v23-v6si11743918pfl.233.2018.05.15.00.02.20; Tue, 15 May 2018 00:02:34 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752372AbeEOHAN convert rfc822-to-8bit (ORCPT + 99 others); Tue, 15 May 2018 03:00:13 -0400 Received: from terminus.zytor.com ([198.137.202.136]:54563 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752059AbeEOHAM (ORCPT ); Tue, 15 May 2018 03:00:12 -0400 Received: from wld62.hos.anvin.org (c-24-5-245-234.hsd1.ca.comcast.net [24.5.245.234] (may be forged)) (authenticated bits=0) by mail.zytor.com (8.15.2/8.15.2) with ESMTPSA id w4F6xdna1054744 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO); Mon, 14 May 2018 23:59:39 -0700 Date: Mon, 14 May 2018 23:59:32 -0700 User-Agent: K-9 Mail for Android In-Reply-To: <20180515065405.GA31240@gmail.com> References: <20180507213755.GA32406@avx2> <20fb84fd5eef4c45b2d38d0290235d5d@AcuMS.aculab.com> <5c6762fe-5cbe-42ed-ac4e-a7144b8ef7ad@zytor.com> <83866d054b27419c9d9dd97d9c66c3de@AcuMS.aculab.com> <20180515065405.GA31240@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Subject: Re: [PATCH] x86: pad assembly functions with INT3 To: Ingo Molnar CC: David Laight , "'Alexey Dobriyan'" , "tglx@linutronix.de" , "mingo@redhat.com" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" From: hpa@zytor.com Message-ID: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On May 14, 2018 11:54:05 PM PDT, Ingo Molnar wrote: > >* hpa@zytor.com wrote: > >> > I guess it won't try to speculatively execute the 'pad' >instructions - but you >> > can never really tell! >> > >> > David >> >> The CPU doesn't speculate down past an unconditional control >transfer. Doing so >> would be idiotic. > >I think, when it comes to speculative execution, our general >expectation that CPUs >don't do idiotic things got somewhat weakened in the past year or so >... > >Thanks, > > Ingo Sort-of-kind-of... the things that have cropped up were reasonable consequences of designing under a set of assumptions which turned out to be incorrect. Speculating through an unconditional control transfer did not make sense under those assumptions either. -- Sent from my Android device with K-9 Mail. Please excuse my brevity.