From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752423AbeEOHAO convert rfc822-to-8bit (ORCPT ); Tue, 15 May 2018 03:00:14 -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 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 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.