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=-4.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 38C9FC10DCE for ; Sat, 7 Mar 2020 01:53:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00415206E2 for ; Sat, 7 Mar 2020 01:53:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583546036; bh=mQv/gm1JDvQ+NoQtrtDoSNIjFb/SqMpZqNM/ofjbOmE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=TbYK0rNpq3N12pxp9Tb8VnyLT+LwpgPgXqHhYwzVYalInxqSAXNSmuHGerl0+EuZ3 jxLOwuOdKASsfmIS0b7r0KoPxwY5IF3KDXfEnvbOyL/OZnT/LjDE5aSGmdsyexrzb2 1TGitIfL8VbKXj79IRjtADbmNdRS9eCsR5Coj+F0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726635AbgCGBxw (ORCPT ); Fri, 6 Mar 2020 20:53:52 -0500 Received: from mail.kernel.org ([198.145.29.99]:50928 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726237AbgCGBxv (ORCPT ); Fri, 6 Mar 2020 20:53:51 -0500 Received: from devnote2 (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 819C3206CC; Sat, 7 Mar 2020 01:53:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1583546031; bh=mQv/gm1JDvQ+NoQtrtDoSNIjFb/SqMpZqNM/ofjbOmE=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XXNcL/8YTAvxKRfeJOftINjDpRcvOhhTODR4YfaMrowdmWIszZ0Ln7DTdwYueBJ9O J3zK+sNiux0+bmTbSFasMzqfMSp0J3j+WE0f/4XtQTrE5k9w7dDjLC9+T/963HuLv6 jjaTANNemCC95JEHpYyIl19m7luE7zeEx1lYEjPk= Date: Sat, 7 Mar 2020 10:53:45 +0900 From: Masami Hiramatsu To: Peter Zijlstra Cc: Steven Rostedt , Andy Lutomirski , LKML , linux-arch , Ingo Molnar , Joel Fernandes , Greg KH , gustavo@embeddedor.com, Thomas Gleixner , paulmck@kernel.org, Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Tony Luck , Frederic Weisbecker , Dan Carpenter , Masami Hiramatsu Subject: Re: [PATCH v4 05/27] x86: Replace ist_enter() with nmi_enter() Message-Id: <20200307105345.e33c2ced6d1f020e1bf91018@kernel.org> In-Reply-To: <20200226102758.GV18400@hirez.programming.kicks-ass.net> References: <20200221133416.777099322@infradead.org> <20200221134215.328642621@infradead.org> <20200221202246.GA14897@hirez.programming.kicks-ass.net> <20200224104346.GJ14946@hirez.programming.kicks-ass.net> <20200224112708.4f307ba3@gandalf.local.home> <20200224163409.GJ18400@hirez.programming.kicks-ass.net> <20200224114754.0fb798c1@gandalf.local.home> <20200224213139.GO11457@worktop.programming.kicks-ass.net> <20200224170231.3807931d@gandalf.local.home> <20200226102758.GV18400@hirez.programming.kicks-ass.net> X-Mailer: Sylpheed 3.5.1 (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 Hi Peter, On Wed, 26 Feb 2020 11:27:58 +0100 Peter Zijlstra wrote: > On Mon, Feb 24, 2020 at 05:02:31PM -0500, Steven Rostedt wrote: > > > The other is for the hwlat detector that measures the time it was in an > > NMI, as NMIs appear as a hardware latency too. > > Yeah,.. I hate that one. But I ended up with this patch. > > And yes, I know some of those notrace annotations are strictly > unnessecary due to Makefile crap, but having them is _SO_ much easier. > > --- > Subject: x86,tracing: Robustify ftrace_nmi_enter() > From: Peter Zijlstra > Date: Mon Feb 24 23:40:29 CET 2020 > > ftrace_nmi_enter() > trace_hwlat_callback() > trace_clock_local() > sched_clock() > paravirt_sched_clock() > native_sched_clock() > > All must not be traced or kprobed, it will be called from do_debug() > before the kprobe handler. As I found today, we need to make NOKPROBE on exit side too, and this covers exit side. Reviewed-by: Masami Hiramatsu Thank you, > > Signed-off-by: Peter Zijlstra (Intel) > --- > arch/x86/include/asm/paravirt.h | 2 +- > arch/x86/kernel/tsc.c | 7 +++++-- > include/linux/ftrace_irq.h | 4 ++-- > kernel/trace/trace_clock.c | 2 ++ > kernel/trace/trace_hwlat.c | 4 +++- > 5 files changed, 13 insertions(+), 6 deletions(-) > > --- a/arch/x86/include/asm/paravirt.h > +++ b/arch/x86/include/asm/paravirt.h > @@ -17,7 +17,7 @@ > #include > #include > > -static inline unsigned long long paravirt_sched_clock(void) > +static __always_inline unsigned long long paravirt_sched_clock(void) > { > return PVOP_CALL0(unsigned long long, time.sched_clock); > } > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -14,6 +14,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -207,7 +208,7 @@ static void __init cyc2ns_init_secondary > /* > * Scheduler clock - returns current time in nanosec units. > */ > -u64 native_sched_clock(void) > +notrace u64 native_sched_clock(void) > { > if (static_branch_likely(&__use_tsc)) { > u64 tsc_now = rdtsc(); > @@ -228,6 +229,7 @@ u64 native_sched_clock(void) > /* No locking but a rare wrong value is not a big deal: */ > return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); > } > +NOKPROBE_SYMBOL(native_sched_clock); > > /* > * Generate a sched_clock if you already have a TSC value. > @@ -240,10 +242,11 @@ u64 native_sched_clock_from_tsc(u64 tsc) > /* We need to define a real function for sched_clock, to override the > weak default version */ > #ifdef CONFIG_PARAVIRT > -unsigned long long sched_clock(void) > +notrace unsigned long long sched_clock(void) > { > return paravirt_sched_clock(); > } > +NOKPROBE_SYMBOL(sched_clock); > > bool using_native_sched_clock(void) > { > --- a/include/linux/ftrace_irq.h > +++ b/include/linux/ftrace_irq.h > @@ -7,7 +7,7 @@ extern bool trace_hwlat_callback_enabled > extern void trace_hwlat_callback(bool enter); > #endif > > -static inline void ftrace_nmi_enter(void) > +static __always_inline void ftrace_nmi_enter(void) > { > #ifdef CONFIG_HWLAT_TRACER > if (trace_hwlat_callback_enabled) > @@ -15,7 +15,7 @@ static inline void ftrace_nmi_enter(void > #endif > } > > -static inline void ftrace_nmi_exit(void) > +static __always_inline void ftrace_nmi_exit(void) > { > #ifdef CONFIG_HWLAT_TRACER > if (trace_hwlat_callback_enabled) > --- a/kernel/trace/trace_clock.c > +++ b/kernel/trace/trace_clock.c > @@ -22,6 +22,7 @@ > #include > #include > #include > +#include > > /* > * trace_clock_local(): the simplest and least coherent tracing clock. > @@ -44,6 +45,7 @@ u64 notrace trace_clock_local(void) > > return clock; > } > +NOKPROBE_SYMBOL(trace_clock_local); > EXPORT_SYMBOL_GPL(trace_clock_local); > > /* > --- a/kernel/trace/trace_hwlat.c > +++ b/kernel/trace/trace_hwlat.c > @@ -43,6 +43,7 @@ > #include > #include > #include > +#include > #include "trace.h" > > static struct trace_array *hwlat_trace; > @@ -137,7 +138,7 @@ static void trace_hwlat_sample(struct hw > #define init_time(a, b) (a = b) > #define time_u64(a) a > > -void trace_hwlat_callback(bool enter) > +notrace void trace_hwlat_callback(bool enter) > { > if (smp_processor_id() != nmi_cpu) > return; > @@ -156,6 +157,7 @@ void trace_hwlat_callback(bool enter) > if (enter) > nmi_count++; > } > +NOKPROBE_SYMBOL(trace_hwlat_callback); > > /** > * get_sample - sample the CPU TSC and look for likely hardware latencies -- Masami Hiramatsu