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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 E4952C072B5 for ; Fri, 24 May 2019 13:36:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BFFB22184E for ; Fri, 24 May 2019 13:36:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403869AbfEXNgD (ORCPT ); Fri, 24 May 2019 09:36:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:42996 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403788AbfEXNgC (ORCPT ); Fri, 24 May 2019 09:36:02 -0400 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 874F1217F9; Fri, 24 May 2019 13:36:01 +0000 (UTC) Date: Fri, 24 May 2019 09:36:00 -0400 From: Steven Rostedt To: Julien Thierry Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Marc Zyngier , Mark Rutland , Daniel Lezcano , Thomas Gleixner Subject: Re: [PATCH] clocksource/arm_arch_timer: Don't trace count reader functions Message-ID: <20190524093600.11ca3cb2@gandalf.local.home> In-Reply-To: <1558689025-50679-1-git-send-email-julien.thierry@arm.com> References: <1558689025-50679-1-git-send-email-julien.thierry@arm.com> 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 Fri, 24 May 2019 10:10:25 +0100 Julien Thierry wrote: > With v5.2-rc1, The ftrace functions_graph tracer locks up whenever it is > enabled on arm64. > > Since commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use > arch_timer_read_counter to access stable counters") a function pointer > is consistently used to read the counter instead of potentially > referencing an inlinable function. > > The graph tacers relies on accessing the timer counters to compute the > time spent in functions which causes the lockup when attempting to trace > these code paths. > > Annontate the arm arch timer counter accessors as notrace. > > Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use > arch_timer_read_counter to access stable counters") > Signed-off-by: Julien Thierry > Cc: Marc Zyngier > Cc: Mark Rutland > Cc: Daniel Lezcano > Cc: Thomas Gleixner > Cc: Steven Rostedt > --- > drivers/clocksource/arm_arch_timer.c | 8 ++++---- Is there any reason to function trace any of the functions in this file? If not, then I would suggest removing all the "notrace" annotations from this file, and add in the Makefile for this directory: CFLAGS_REMOVE_arm_arch_timer.o = $(CC_FLAGS_FTRACE) Hmm, I need to go through all the Makefiles in the kernel and remove the "-pg" and replace it with "$(CC_FLAGS_FTRACE)" as that's the safer way of doing it now. -- Steve > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c > index b2a951a..5c69c9a 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -149,22 +149,22 @@ u32 arch_timer_reg_read(int access, enum arch_timer_reg reg, > return val; > } > > -static u64 arch_counter_get_cntpct_stable(void) > +static notrace u64 arch_counter_get_cntpct_stable(void) > { > return __arch_counter_get_cntpct_stable(); > } > > -static u64 arch_counter_get_cntpct(void) > +static notrace u64 arch_counter_get_cntpct(void) > { > return __arch_counter_get_cntpct(); > } > > -static u64 arch_counter_get_cntvct_stable(void) > +static notrace u64 arch_counter_get_cntvct_stable(void) > { > return __arch_counter_get_cntvct_stable(); > } > > -static u64 arch_counter_get_cntvct(void) > +static notrace u64 arch_counter_get_cntvct(void) > { > return __arch_counter_get_cntvct(); > }