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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 BA4E6ECE588 for ; Wed, 16 Oct 2019 09:23:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9274720650 for ; Wed, 16 Oct 2019 09:23:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="APm/cn8a" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391943AbfJPJXT (ORCPT ); Wed, 16 Oct 2019 05:23:19 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:59346 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726480AbfJPJXT (ORCPT ); Wed, 16 Oct 2019 05:23:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=5AcyBsYweHc63jioDghXMYrjt1pzca504Ibkz/xNS90=; b=APm/cn8akSdHbAKBaJTgMqgPz YdUieszdrJiBZjPyt9L9nocPXj8My528/yeh8YgGkL26CY7BjfVwjzZxHjp4x+pxdlQL31JO6He8d cr+ntUbFKU5gbzeEhxOxW7U8XZDPsxpnjBr2Qz28Nu2idlfY8mK2D0E3GtGDOM/Dw3VWbOZ5TfkRO JkfGCJGMjl4sm+OBMIzDe3gta89HiqZPlxY8XY3T3wqgbRDYZw+kjj3ulYOtUNFbtVQug+sXwduzs Wn9UztxVgEuBedCAnAfouyotKFv2pO4C2pwMY63H/I4CIZhcU6ZDJF5Xw7EJJs6zaC2eVzCfZfmB5 fa/hdBppA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iKfWN-0001zK-E0; Wed, 16 Oct 2019 09:23:07 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id AC6B03032F8; Wed, 16 Oct 2019 11:22:09 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 8055B2042784A; Wed, 16 Oct 2019 11:23:04 +0200 (CEST) Date: Wed, 16 Oct 2019 11:23:04 +0200 From: Peter Zijlstra To: Miroslav Benes Cc: Joe Lawrence , Jessica Yu , Steven Rostedt , x86@kernel.org, linux-kernel@vger.kernel.org, mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com, torvalds@linux-foundation.org, tglx@linutronix.de, mingo@kernel.org, namit@vmware.com, hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org, jpoimboe@redhat.com, live-patching@vger.kernel.org Subject: Re: [PATCH v3 5/6] x86/ftrace: Use text_poke() Message-ID: <20191016092304.GL2294@hirez.programming.kicks-ass.net> References: <20191010091956.48fbcf42@gandalf.local.home> <20191010140513.GT2311@hirez.programming.kicks-ass.net> <20191010115449.22044b53@gandalf.local.home> <20191010172819.GS2328@hirez.programming.kicks-ass.net> <20191011125903.GN2359@hirez.programming.kicks-ass.net> <20191015130739.GA23565@linux-8ccs> <20191015135634.GK2328@hirez.programming.kicks-ass.net> <88bab814-ea24-ece9-2bc0-7a1e10a62f12@redhat.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 On Wed, Oct 16, 2019 at 08:51:27AM +0200, Miroslav Benes wrote: > On Tue, 15 Oct 2019, Joe Lawrence wrote: > > > On 10/15/19 10:13 AM, Miroslav Benes wrote: > > > Yes, it does. klp_module_coming() calls module_disable_ro() on all > > > patching modules which patch the coming module in order to call > > > apply_relocate_add(). New (patching) code for a module can be relocated > > > only when the relevant module is loaded. > > > > FWIW, would the LPC blue-sky2 model (ie, Steve's suggestion @ plumber's where > > livepatches only patch a single object and updates are kept on disk to handle > > coming module updates as they are loaded) eliminate those outstanding > > relocations and the need to perform this late permission flipping? > > Yes, it should, but we don't have to wait for it. PeterZ proposed a > different solution to this specific issue in > https://lore.kernel.org/lkml/20191015141111.GP2359@hirez.programming.kicks-ass.net/ > > It should not be a problem to create a live patch module like that and the > code in kernel/livepatch/ is almost ready. Something like > module_section_disable_ro(mod, section) (and similar for X protection) > should be enough. Module reloads would still require juggling with the > protections, but I think it is all feasible. Just had a browse around the module code, and while the section info is in load_info, it doesn't get retained for active modules. So I suppose I'll go add that for KLP enabled things.