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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 1CB09C2BB55 for ; Thu, 16 Apr 2020 15:45:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE16320732 for ; Thu, 16 Apr 2020 15:45:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="W/6fVJAm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2442550AbgDPPpi (ORCPT ); Thu, 16 Apr 2020 11:45:38 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:22274 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2404060AbgDPPpW (ORCPT ); Thu, 16 Apr 2020 11:45:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587051920; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=+utDsScgznwxfIms0Xj6ZFYVx2OkbDAV0iH3XU6eMzc=; b=W/6fVJAmg+HnuDqQq3dq1qI2gsP2Ts7BBg5W1YsQ/kc7Ti62jVJ5TGxwH/TnizSoxmW+S2 dA2hxbt9oqgcV3GWdo8C+c2j4Zlk66a4XYiHcsIBRMHVqLDMjvER02YwpG492aWCeht5oO AqHautWJNX1DLuSIWnslmIR4rS5XrrE= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-381-FQtd2CPSM-iv5pZfWUtpgg-1; Thu, 16 Apr 2020 11:45:18 -0400 X-MC-Unique: FQtd2CPSM-iv5pZfWUtpgg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ED02C107ACC9; Thu, 16 Apr 2020 15:45:16 +0000 (UTC) Received: from treble (ovpn-116-146.rdu2.redhat.com [10.10.116.146]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4D0647E7D4; Thu, 16 Apr 2020 15:45:16 +0000 (UTC) Date: Thu, 16 Apr 2020 10:45:14 -0500 From: Josh Poimboeuf To: Jessica Yu Cc: Peter Zijlstra , live-patching@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/7] livepatch,module: Remove .klp.arch and module_disable_ro() Message-ID: <20200416154514.xqqyvdtm6hjynbx2@treble> References: <20200414182726.GF2483@worktop.programming.kicks-ass.net> <20200414190814.glra2gceqgy34iyx@treble> <20200415142415.GH20730@hirez.programming.kicks-ass.net> <20200415161706.3tw5o4se2cakxmql@treble> <20200416153131.GC6164@linux-8ccs.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200416153131.GC6164@linux-8ccs.fritz.box> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 16, 2020 at 05:31:31PM +0200, Jessica Yu wrote: > > But I still not a fan of the fact that COMING has two different > > "states". For example, after your patch, when apply_relocate_add() is > > called from klp_module_coming(), it can use memcpy(), but when called > > from klp module init() it has to use text poke. But both are COMING so > > there's no way to look at the module state to know which can be used. > > This is a good observation, thanks for bringing it up. I agree that we > should strive to be consistent with what the module states mean. In my > head, I think it is easiest to assume/establish the following meanings > for each module state: > > MODULE_STATE_UNFORMED - no protections. relocations, alternatives, > ftrace module initialization, etc. any other text modifications are > in the process of being applied. Direct writes are permissible. > > MODULE_STATE_COMING - module fully formed, text modifications are > done, protections applied, module is ready to execute init or is > executing init. > > I wonder if we could enforce the meaning of these two states more > consistently without needing to add another module state. > > Regarding Peter's patches, with the set_all_modules_text_*() api gone, > and ftrace reliance on MODULE_STATE_COMING gone (I think?), is there > anything preventing ftrace_module_init+enable from being called > earlier (i.e., before complete_formation()) while the module is > unformed? Then you don't have to move module_enable_ro/nx later and we > keep the MODULE_STATE_COMING semantics. And if we're enforcing the > above module state meanings, I would also be OK with moving jump_label > and static_call out of the coming notifier chain and making them > explicit calls while the module is still writable. > > Sorry in advance if I missed anything above, I'm still trying to wrap > my head around which callers need what module state and what module > permissions :/ Sounds reasonable to me... BTW, instead of hard-coding the jump-label/static-call/ftrace calls, we could instead call notifiers with MODULE_STATE_UNFORMED. -- Josh