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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 1F478C43331 for ; Fri, 3 Apr 2020 08:09:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EE72D2073B for ; Fri, 3 Apr 2020 08:09:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390414AbgDCIJJ convert rfc822-to-8bit (ORCPT ); Fri, 3 Apr 2020 04:09:09 -0400 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:23780 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727431AbgDCIJJ (ORCPT ); Fri, 3 Apr 2020 04:09:09 -0400 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-216-2nJT-0BSNJKCaNUE6rLCiQ-1; Fri, 03 Apr 2020 09:09:04 +0100 X-MC-Unique: 2nJT-0BSNJKCaNUE6rLCiQ-1 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Fri, 3 Apr 2020 09:09:03 +0100 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Fri, 3 Apr 2020 09:09:03 +0100 From: David Laight To: 'Peter Zijlstra' , Thomas Gleixner CC: LKML , "x86@kernel.org" , "Kenneth R. Crudup" , Paolo Bonzini , Jessica Yu , Fenghua Yu , Xiaoyao Li , Nadav Amit , Thomas Hellstrom , Sean Christopherson , Tony Luck , "Steven Rostedt" Subject: RE: [patch v2 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect Thread-Topic: [patch v2 1/2] x86,module: Detect VMX modules and disable Split-Lock-Detect Thread-Index: AQHWCQK4i0gO2diBOkK6XKhOFlCL2qhnC2Fg Date: Fri, 3 Apr 2020 08:09:03 +0000 Message-ID: <9b95fe9e81c14370859e19f081cc23e4@AcuMS.aculab.com> References: <20200402123258.895628824@linutronix.de> <20200402124205.242674296@linutronix.de> <20200402152340.GL20713@hirez.programming.kicks-ass.net> In-Reply-To: <20200402152340.GL20713@hirez.programming.kicks-ass.net> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Peter Zijlstra > Sent: 02 April 2020 16:24 > > I picked VMXOFF (which also appears in vmmon.ko) instead of VMXON > because that latter takes an argument is therefore more difficult to > decode. ... > + while (text < text_end) { > + kernel_insn_init(&insn, text, text_end - text); > + insn_get_length(&insn); > + > + if (WARN_ON_ONCE(!insn_complete(&insn))) > + break; > + > + if (insn.length == 3 && > + (!memcmp(text, vmlaunch, sizeof(vmlaunch)) || > + !memcmp(text, vmxoff, sizeof(vmxoff)))) > + goto bad_module; > + > + text += insn.length; > + } How long is that going to take on a module with (say) 400k of text? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)