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 1F174C4360C for ; Wed, 16 Oct 2019 07:50:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EC0782082C for ; Wed, 16 Oct 2019 07:50:04 +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="KCZ+f1LS" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391374AbfJPHuD (ORCPT ); Wed, 16 Oct 2019 03:50:03 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:57086 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391302AbfJPHuD (ORCPT ); Wed, 16 Oct 2019 03:50:03 -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=gHzug1GaUc7ezNj7bFyKz/sT6qVftQ/c/eZSM2ZX/yA=; b=KCZ+f1LSz+WgwwiREH87xcTq/ gdAvldI5Mhnc/Q14EWgLX8/WgPcNqstNJEAWsC5WoFJHN+AxJtLVDmeP9Qmf1IRwh/ho/R4hTHGgw MVY8hfrR2oLY+aCCeR8uMeudZ2hNu21TKkPW4RZkvYIAcIes4+edKfjInFEG10Yg9y/t0UwCGAEws 0Tsp1c2BB+5htwUkDzZuv8VVC5p3AahL7ThhupbnCqduKuC+6NSo9mg9AH8eE+jllee2nJ6eV8pmZ GRzY87IwtVS1UFmc2euekMg/WlWdrK0MQkIjkt5aXdrTqY66a5Z8c2OEQrIoCowYWG3LeTHMl+HoP 0C78MuyDw==; 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 1iKe49-0001yz-LA; Wed, 16 Oct 2019 07:49:54 +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 6F197303C1E; Wed, 16 Oct 2019 09:48:56 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 3936520B972E4; Wed, 16 Oct 2019 09:49:51 +0200 (CEST) Date: Wed, 16 Oct 2019 09:49:51 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: Joe Lawrence , Jessica Yu , Miroslav Benes , 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: <20191016074951.GM2328@hirez.programming.kicks-ass.net> References: <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> <20191015153120.GA21580@linux-8ccs> <7e9c7dd1-809e-f130-26a3-3d3328477437@redhat.com> <20191015182705.1aeec284@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191015182705.1aeec284@gandalf.local.home> 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 06:27:05PM -0400, Steven Rostedt wrote: > (7) Seventh session, titled "klp-convert and livepatch relocations", was led > by Joe Lawrence. > > Joe started the session with problem statement: accessing non exported / static > symbols from inside the patch module. One possible workardound is manually via > kallsyms. Second workaround is klp-convert, which actually creates proper > relocations inside the livepatch module from the symbol database during the > final .ko link. > Currently module loader looks for special livepatch relocations and resolves > those during runtime; kernel support for these relocations have so far been > added for x86 only. Special livepatch relocations are supported and processed > also on other architectures. Special quirks/sections are not yet supported. > Plus klp-convert would still be needed even with late module patching update. > vmlinux or modules could have ambiguous static symbols. > > It turns out that the features / bugs below have to be resolved before we > can claim the klp-convert support for relocation complete: > - handle all the corner cases (jump labels, static keys, ...) properly and > have a good regression tests in place I suppose all the patches in this series-of-series here will make life harder for KLP, static_call() and 2 byte jumps etc.. > - one day we might (or might not) add support for out-of-tree modules which > need klp-convert > - BFD bug 24456 (multiple relocations to the same .text section)