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=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 49D86C43143 for ; Fri, 28 Sep 2018 20:59:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D694F206B8 for ; Fri, 28 Sep 2018 20:59:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D694F206B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727251AbeI2DZH (ORCPT ); Fri, 28 Sep 2018 23:25:07 -0400 Received: from mga14.intel.com ([192.55.52.115]:39204 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727069AbeI2DZH (ORCPT ); Fri, 28 Sep 2018 23:25:07 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 28 Sep 2018 13:59:36 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,316,1534834800"; d="scan'208";a="95884402" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.7.201.126]) by orsmga002.jf.intel.com with ESMTP; 28 Sep 2018 13:59:07 -0700 Received: by tassilo.localdomain (Postfix, from userid 1000) id 33B69300B51; Fri, 28 Sep 2018 13:59:07 -0700 (PDT) Date: Fri, 28 Sep 2018 13:59:07 -0700 From: Andi Kleen To: Jann Horn Cc: Mark Rutland , Thomas Gleixner , tursulin@ursulin.net, kernel list , tvrtko.ursulin@linux.intel.com, Peter Zijlstra , the arch/x86 maintainers , "H . Peter Anvin" , acme@kernel.org, alexander.shishkin@linux.intel.com, jolsa@redhat.com, namhyung@kernel.org, maddy@linux.vnet.ibm.com, alexey.budankov@linux.intel.com, Kees Cook Subject: Re: [RFC 0/5] perf: Per PMU access controls (paranoid setting) Message-ID: <20180928205907.GD32651@tassilo.jf.intel.com> References: <20180919122751.12439-1-tvrtko.ursulin@linux.intel.com> <20180928164111.i6nba2j6mnegwslw@lakrids.cambridge.arm.com> <20180928172340.GA32651@tassilo.jf.intel.com> <20180928174016.i7d24puv7y3jwzf6@lakrids.cambridge.arm.com> <20180928204930.GC32651@tassilo.jf.intel.com> 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 > > This new file descriptor argument doesn't exist today so it would > > need to create a new system call with more arguments > > Is that true? The first argument is a pointer to a struct that > contains its own size, so it can be expanded without an ABI break. I > don't see any reason why you couldn't cram more stuff in there. You're right we could put the fd into the perf_event, but the following is still true: > > Obviously we would need to keep the old system call around > > for compability, so you would need to worry about this > > interaction in any case! > > > > So tying it together doesn't make any sense, because > > the problem has to be solved separately anyways. -Andi