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=-2.1 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 88F2DC10F14 for ; Tue, 15 Oct 2019 14:11:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58D1D2054F for ; Tue, 15 Oct 2019 14:11:30 +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="WmdCERaA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732478AbfJOOL3 (ORCPT ); Tue, 15 Oct 2019 10:11:29 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:52112 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731977AbfJOOL2 (ORCPT ); Tue, 15 Oct 2019 10:11:28 -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=u3AIL5Yut/d4CJmU5Dy8pm81xE/du7Qm4bFCGyoGlWQ=; b=WmdCERaAPalLY+SN9/TiCZoEO ibdhiLkjYDqIIZMAN2C5Gr9DJHd0t6I3MPg5p+sndTcJcpHbwnVFbK8jb+DPunf0JqC71S+Bda3Jg yftHujgMwq99qM0apSFBPE2woj+EdeWHxXEK+8hrehyZIQlbK4bhS0YvnjoTV563crPzFM7uDuger Gh6p28BGAeQqHv2H8oOJWh32EEGZ/+r0/UWwsY8/jAjzLOKmZ0qZNPfn82wFlRhArLM+vH519yNjD 5kNa3JAHKUu/h5mEI5z445BUMigYj8MroXu64Bn1S0y08tEZzHFr9n5p+PAKRGyM+yXG8f4xTcO2T 5NgaGupig==; 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 1iKNXe-0001Pb-4v; Tue, 15 Oct 2019 14:11:14 +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 5B56B303DDD; Tue, 15 Oct 2019 16:10:17 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 903B029A873D5; Tue, 15 Oct 2019 16:11:11 +0200 (CEST) Date: Tue, 15 Oct 2019 16:11:11 +0200 From: Peter Zijlstra To: Jessica Yu Cc: 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, mbenes@suse.cz Subject: Re: [PATCH v3 5/6] x86/ftrace: Use text_poke() Message-ID: <20191015141111.GP2359@hirez.programming.kicks-ass.net> References: <20191008104335.6fcd78c9@gandalf.local.home> <20191009224135.2dcf7767@oasis.local.home> <20191010092054.GR2311@hirez.programming.kicks-ass.net> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191015135634.GK2328@hirez.programming.kicks-ass.net> 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 Tue, Oct 15, 2019 at 03:56:34PM +0200, Peter Zijlstra wrote: > On Tue, Oct 15, 2019 at 03:07:40PM +0200, Jessica Yu wrote: > > > Once this ftrace thing is sorted, we'll change x86 to _refuse_ to make > > > executable (kernel) memory writable. > > > > Not sure if relevant, but just thought I'd clarify: IIRC, > > klp_module_coming() is not poking the coming module, but it calls > > module_enable_ro() on itself (the livepatch module) so it can apply > > relocations and such on the new code, which lives inside the livepatch > > module, and it needs to possibly do this numerous times over the > > lifetime of the patch module for any coming module it is responsible > > for patching (i.e., call module_enable_ro() on the patch module, not > > necessarily the coming module). So I am not be sure why > > klp_module_coming() should be moved before complete_formation(). I > > hope I'm remembering the details correctly, livepatch folks feel free > > to chime in if I'm incorrect here. > > You mean it does module_disable_ro() ? That would be broken and it needs > to be fixed. Can some livepatch person explain what it does and why? mbenes confirmed; what would be needed is for the live-patch module to have all module dependent parts to be in their own section and have the sections be page-aligned. Then we can do the protection on sections instead of on the whole module. Damn, and I thought I was so close to getting W^X sorted :/