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 9ABEDC4BA21 for ; Wed, 26 Feb 2020 19:00:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6D22920578 for ; Wed, 26 Feb 2020 19:00:07 +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="GuhnEH1a" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727350AbgBZTAG (ORCPT ); Wed, 26 Feb 2020 14:00:06 -0500 Received: from merlin.infradead.org ([205.233.59.134]:44458 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727189AbgBZTAF (ORCPT ); Wed, 26 Feb 2020 14:00:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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; bh=CAFrV/jX2REFdROj2WFmW9nBm7NNscB1OT89QWcHs0s=; b=GuhnEH1adpeERgL5XOpo1papgf 6i/2avLHdyfXH2/N9OXemsbJMVJzKSSzj7StSKPbDhNXvJENlGc1UNqLo+/s9RjpP9PDB4SItcPQ5 SFGw1HjhVb1vkjyeiGu/ZkDdOujivbzxWlgBXzCPIlG67W46OYnGZVcTYCUyFK0aHlCtl+DbsJZxw vmjQ+JD2Q4mzs6ekgdbpjMpGqbcHc02KWEdAvFdQEC1vyAY1Os050YsM1Mdqxq0ivJDUljUL8Hf5y NRvhh9Q74R7Lq1JeDSviGrsA02UyMp1y78zQPG5lQtMOH3FZ0b2uiJsq6grB/9cNzUF5HIXi4HMsT 7QEY1f9A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1j71uO-0004Zc-Hc; Wed, 26 Feb 2020 18:59:48 +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 365B5300130; Wed, 26 Feb 2020 19:57:50 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C42422B740B89; Wed, 26 Feb 2020 19:59:45 +0100 (CET) Date: Wed, 26 Feb 2020 19:59:45 +0100 From: Peter Zijlstra To: Borislav Petkov Cc: Andy Lutomirski , Andy Lutomirski , Frederic Weisbecker , Thomas Gleixner , LKML , X86 ML , Steven Rostedt , Brian Gerst , Juergen Gross , Paolo Bonzini , Arnd Bergmann Subject: Re: [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check() Message-ID: <20200226185945.GC18400@hirez.programming.kicks-ass.net> References: <20200226160818.GY18400@hirez.programming.kicks-ass.net> <20200226184237.GB16756@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200226184237.GB16756@zn.tnic> 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, Feb 26, 2020 at 07:42:37PM +0100, Borislav Petkov wrote: > On Wed, Feb 26, 2020 at 09:28:51AM -0800, Andy Lutomirski wrote: > > > It entirely depends on what the goal is :-/ On the one hand I see why > > > people might want function tracing / kprobes enabled, OTOH it's all > > > mighty frigging scary. Any tracing/probing/whatever on an MCE has the > > > potential to make a bad situation worse -- not unlike the same on #DF. > > FWIW, I had this at the beginning of the #MC handler in a feeble attempt > to poke at this: > > + hw_breakpoint_disable(); > + static_key_disable(&__tracepoint_read_msr.key); > + tracing_off(); You can't do static_key_disable() from an IST