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 3626CC2BA83 for ; Wed, 12 Feb 2020 11:59:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 045252082F for ; Wed, 12 Feb 2020 11:59:02 +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="gfuS8CH6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728245AbgBLL7B (ORCPT ); Wed, 12 Feb 2020 06:59:01 -0500 Received: from merlin.infradead.org ([205.233.59.134]:42966 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725874AbgBLL7B (ORCPT ); Wed, 12 Feb 2020 06:59:01 -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=UtN8+ZGSwaPi4q3QVj9G5VCoQ9BSx691y8FRqSthTXE=; b=gfuS8CH6o/kkTpvRENuT4/WSp6 Y1BM52nqcvQS6tgzL2xqmbDAkKG7Jr6sk9ZDzBWzdwXp7Iy9EJoUlEwTS/4xCj7vncjj0n3vSkoV9 nahwIJUwMVAeXMgzUH0Oewx0QZU9xdoM6/MhGfPYhIIv7oALnyNi4aJT19l1/9n//M0qqDnMvnfT0 fkbLe46TnBDnbrgTdk7xPQzJR7xs7O6UK2mcDbNLKYhuGt/08Zi7obelcfwVNU4DOZ/CkabnfSNIr 6X5HPVho9NcDDmB9ABXR5kdCxjg4qcbeloJ3tfQVY275abz/7mAVKP50cbqNeEXgYtppW7MbCfbzo HJJBZbeA==; 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 1j1qet-0000HP-OM; Wed, 12 Feb 2020 11:58:23 +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 1C224300235; Wed, 12 Feb 2020 12:56:30 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 1683120148932; Wed, 12 Feb 2020 12:58:20 +0100 (CET) Date: Wed, 12 Feb 2020 12:58:20 +0100 From: Peter Zijlstra To: Will Deacon 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: <20200212115820.GQ14897@hirez.programming.kicks-ass.net> References: <20200212093210.468391728@infradead.org> <20200212100106.GA14914@hirez.programming.kicks-ass.net> <20200212105646.GA4017@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200212105646.GA4017@willie-the-truck> 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 10:56:46AM +0000, Will Deacon wrote: > 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... I'm not sure. In fact, I asked Steve on IRC if we'd want to teach objtool to report such inconsitencies.