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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 C3490C2BA83 for ; Wed, 12 Feb 2020 10:56:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9B8452082F for ; Wed, 12 Feb 2020 10:56:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581505014; bh=4pZYCUBDsbqAJS8ZCZ6TjAOwz6/YRSffWxenSOtB50U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=zGvxdOcDRi/U2qdTSq1RuqUXdCNUl/ciwstwlq/82eT2vcVk80OlpBh5eSqLPj4VJ +I9wyFlHHwL/TJT8vLvS0VfxdcWTTHGxzDI2q9gstCY0VKKIObwd+65Atzo9ai48p7 9XU0oZOcrpPyk3hKDXFm5UZBOwup2jJUvmOmITnk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728042AbgBLK4y (ORCPT ); Wed, 12 Feb 2020 05:56:54 -0500 Received: from mail.kernel.org ([198.145.29.99]:59450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727594AbgBLK4w (ORCPT ); Wed, 12 Feb 2020 05:56:52 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AD1D620675; Wed, 12 Feb 2020 10:56:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581505012; bh=4pZYCUBDsbqAJS8ZCZ6TjAOwz6/YRSffWxenSOtB50U=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=QRgU7x7TZli8ZVmDnLJzwtnNVmdWfAHB0Q/qll4v64rUTI4fE8Dojv/BMAco567EH jgUYQ8+QHsY1GFzOLk7bhC8SELeIyM765FUHJr+guMH4xXt2YZUleDsnsYhJNVl5e2 2sLuwCG2V2jkGnmXd4wcDg3I1kLckzO67mW9qQQU= Date: Wed, 12 Feb 2020 10:56:46 +0000 From: Will Deacon To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, rostedt@goodmis.org, james.morse@arm.com, catalin.marinas@arm.com, mingo@kernel.org, joel@joelfernandes.org, gregkh@linuxfoundation.org, gustavo@embeddedor.com, tglx@linutronix.de, paulmck@kernel.org, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com Subject: Re: [PATCH 0/8] tracing vs rcu vs nmi Message-ID: <20200212105646.GA4017@willie-the-truck> References: <20200212093210.468391728@infradead.org> <20200212100106.GA14914@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200212100106.GA14914@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 Wed, Feb 12, 2020 at 11:01:06AM +0100, Peter Zijlstra wrote: > On Wed, Feb 12, 2020 at 10:32:10AM +0100, Peter Zijlstra wrote: > > Hi all, > > > > These here patches are the result of Mathieu and Steve trying to get commit > > 865e63b04e9b2 ("tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle > > tracepoints") reverted again. > > > > One of the things discovered is that tracing MUST NOT happen before nmi_enter() > > or after nmi_exit(). I've only fixed x86, but quickly gone through other > > architectures and there is definitely more stuff to be fixed (simply grep for > > nmi_enter in your arch). > > For ARM64: > > - apei_claim_sea() > - __sdei_handler() > - do_serror() > - debug_exception_enter() / do_debug_exception() > > all look dodgy. Hmm, so looks like we need to spinkle some 'notrace' annotations around these. Are there are scenarios where you would want NOKPROBE_SYMBOL() but *not* 'notrace'? We've already got the former for the debug exception handlers and we probably (?) want it for the SDEI stuff too... Will