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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2C080C433EF for ; Wed, 12 Jan 2022 16:38:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349829AbiALQiJ (ORCPT ); Wed, 12 Jan 2022 11:38:09 -0500 Received: from mail.efficios.com ([167.114.26.124]:39872 "EHLO mail.efficios.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343550AbiALQiH (ORCPT ); Wed, 12 Jan 2022 11:38:07 -0500 Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id BD4AB2578BE; Wed, 12 Jan 2022 11:38:06 -0500 (EST) Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10032) with ESMTP id xlU9B2-5QPf1; Wed, 12 Jan 2022 11:38:06 -0500 (EST) Received: from localhost (localhost [127.0.0.1]) by mail.efficios.com (Postfix) with ESMTP id 1213225799F; Wed, 12 Jan 2022 11:38:06 -0500 (EST) DKIM-Filter: OpenDKIM Filter v2.10.3 mail.efficios.com 1213225799F DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=efficios.com; s=default; t=1642005486; bh=g9f7dG+bhNKpizysyUoQp+wUex1LU175g8hrrfqMfiE=; h=Date:From:To:Message-ID:MIME-Version; b=oUYGLzxW7kN56OZ3buj3XtfWITjaoWI4Whuj09aFDuNpCxf41LWDicIYOsE4RzCRP eDgfgqqtkCeldPgTgPEaEFUqkkgyy78gpIa/8wYnoTVJ9F5xzki7wcS1QszL4civ9J W5vrl0vHHZlqoCsJkWxDZKIWxXtzhE3VOUlZl1LYqa4+GbmyhzeO7CBxeW+Lw0f2VW vkWkaqco9iprqHDk34QxgLQlaUbBqgWbe4m1ccE8jpWrYK4R+UvvyTaPXEV/0E7TEo JQtTK41GfzGtrdQK53SKVnQwmBp9hMIiBQwYi1TdY3JhULh7RTkCRdqnSIeeucKjk4 aHspZZCsAePwg== X-Virus-Scanned: amavisd-new at efficios.com Received: from mail.efficios.com ([127.0.0.1]) by localhost (mail03.efficios.com [127.0.0.1]) (amavisd-new, port 10026) with ESMTP id D9n8D_sJ4JYi; Wed, 12 Jan 2022 11:38:06 -0500 (EST) Received: from mail03.efficios.com (mail03.efficios.com [167.114.26.124]) by mail.efficios.com (Postfix) with ESMTP id 01062257B05; Wed, 12 Jan 2022 11:38:06 -0500 (EST) Date: Wed, 12 Jan 2022 11:38:05 -0500 (EST) From: Mathieu Desnoyers To: Florian Weimer Cc: Peter Zijlstra , linux-kernel , Thomas Gleixner , paulmck , Boqun Feng , "H. Peter Anvin" , Paul Turner , linux-api , Christian Brauner , carlos Message-ID: <396330808.24806.1642005485899.JavaMail.zimbra@efficios.com> In-Reply-To: <87sftt6j0u.fsf@mid.deneb.enyo.de> References: <20220107170302.8325-1-mathieu.desnoyers@efficios.com> <87a6g7ny0j.fsf@mid.deneb.enyo.de> <1968088162.13310.1641584935813.JavaMail.zimbra@efficios.com> <87y23l6l2j.fsf@mid.deneb.enyo.de> <87sftt6j0u.fsf@mid.deneb.enyo.de> Subject: Re: [RFC PATCH] rseq: x86: implement abort-at-ip extension MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [167.114.26.124] X-Mailer: Zimbra 8.8.15_GA_4180 (ZimbraWebClient - FF96 (Linux)/8.8.15_GA_4177) Thread-Topic: rseq: x86: implement abort-at-ip extension Thread-Index: SzHVQlW/ZeENurobLuAlPowCMIU0hg== Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- On Jan 12, 2022, at 11:00 AM, Florian Weimer fw@deneb.enyo.de wrote: > * Peter Zijlstra: > >> On Wed, Jan 12, 2022 at 04:16:36PM +0100, Florian Weimer wrote: >> >>> You could perhaps push a signal frame onto the stack. It's going to >>> be expensive, but it's already in the context switch path, so maybe it >>> does not matter. >> >> Please no! Signals are a trainwreck that need change (see the whole >> AVX-512 / AMX saga), we shouldn't use more of that just cause. > > If it's a signal, it should be modeled as such. I think it's pretty > close to a synchronous signal. Florian, just to validate here: is your argument about AVX-512/AMX or about rseq abort-at-ip ? Am I understanding correctly that you would prefer that the kernel push an entire signal frame onto the stack rather than just push the abort-at-ip value on abort ? If it is the case, are there advantages in doing so ? Tooling support ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com