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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=ham 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 3AA3FC2BA83 for ; Wed, 12 Feb 2020 14:25:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0975021569 for ; Wed, 12 Feb 2020 14:25:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728386AbgBLOZm (ORCPT ); Wed, 12 Feb 2020 09:25:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:43578 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727963AbgBLOZm (ORCPT ); Wed, 12 Feb 2020 09:25:42 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 CACE120873; Wed, 12 Feb 2020 14:25:40 +0000 (UTC) Date: Wed, 12 Feb 2020 09:25:39 -0500 From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, 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 5/8] x86,tracing: Mark debug_stack_{set_zero,reset)() notrace Message-ID: <20200212092539.135934e1@gandalf.local.home> In-Reply-To: <20200212094107.894657838@infradead.org> References: <20200212093210.468391728@infradead.org> <20200212094107.894657838@infradead.org> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 12 Feb 2020 10:32:15 +0100 Peter Zijlstra wrote: > Because do_nmi() must not call into tracing outside of > nmi_enter()/nmi_exit(), these functions must be notrace. > > Signed-off-by: Peter Zijlstra (Intel) > --- > arch/x86/kernel/cpu/common.c | 4 ++-- > arch/x86/kernel/nmi.c | 6 ++++++ > 2 files changed, 8 insertions(+), 2 deletions(-) > > --- a/arch/x86/kernel/cpu/common.c > +++ b/arch/x86/kernel/cpu/common.c This entire file is notrace: arch/x86/kernel/cpu/Makefile: CFLAGS_REMOVE_common.o = -pg -- Steve > @@ -1690,14 +1690,14 @@ void syscall_init(void) > DEFINE_PER_CPU(int, debug_stack_usage); > DEFINE_PER_CPU(u32, debug_idt_ctr); > > -void debug_stack_set_zero(void) > +void notrace debug_stack_set_zero(void) > { > this_cpu_inc(debug_idt_ctr); > load_current_idt(); > } > NOKPROBE_SYMBOL(debug_stack_set_zero); > > -void debug_stack_reset(void) > +void notrace debug_stack_reset(void) > { > if (WARN_ON(!this_cpu_read(debug_idt_ctr))) > return; > --- a/arch/x86/kernel/nmi.c > +++ b/arch/x86/kernel/nmi.c > @@ -534,6 +534,9 @@ do_nmi(struct pt_regs *regs, long error_ > } > #endif > > + /* > + * It is important that no tracing happens before nmi_enter()! > + */ > nmi_enter(); > > inc_irq_stat(__nmi_count); > @@ -542,6 +545,9 @@ do_nmi(struct pt_regs *regs, long error_ > default_do_nmi(regs); > > nmi_exit(); > + /* > + * No tracing after nmi_exit()! > + */ > > #ifdef CONFIG_X86_64 > if (unlikely(this_cpu_read(update_debug_stack))) { >