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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 94714C10F27 for ; Tue, 10 Mar 2020 10:56:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6067E2468C for ; Tue, 10 Mar 2020 10:56:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="xCZPDG1F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726290AbgCJK4h (ORCPT ); Tue, 10 Mar 2020 06:56:37 -0400 Received: from userp2130.oracle.com ([156.151.31.86]:42794 "EHLO userp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725937AbgCJK4g (ORCPT ); Tue, 10 Mar 2020 06:56:36 -0400 Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02AAqcwN094799; Tue, 10 Mar 2020 10:55:56 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2020-01-29; bh=XXjzFNB9cRgttYtET8dUuiD6TKGwXuCnG+xeyoL7B14=; b=xCZPDG1FV3MzrR3RkkxTniETVeialYVxkXfq+aOUJ4fPHN2HccnQcx8PfKVhjySY+CKD cm5m62lSfL3g5qYVhY7FrOnpQJToQXvw8woD3bFQdwXaAF/osiHxgEC+2HWFYjxP6JoG cKPou7fFYs+uF1WGHYq7zV/SeS/uKbyVezycw/DyfL+mUMo+WviYYI0crGVQi151wE6O tpEvjv3ElMyghJ+CDUmZXNOhkzX+XPjywlakQvsfU6TPOEErRO60SqthgNT+48wyNJYa N91TVy82HG2JqHuJQECRFMZuvfuRSfiLNU1okcENE5u8SZsaUbnHg0sP/I+kTOkMU1db Bw== Received: from userp3030.oracle.com (userp3030.oracle.com [156.151.31.80]) by userp2130.oracle.com with ESMTP id 2ym31ucu7r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 10 Mar 2020 10:55:56 +0000 Received: from pps.filterd (userp3030.oracle.com [127.0.0.1]) by userp3030.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02AAl7Mv189027; Tue, 10 Mar 2020 10:55:55 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3030.oracle.com with ESMTP id 2yp8qmq5ex-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 10 Mar 2020 10:55:55 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 02AAtsQA005766; Tue, 10 Mar 2020 10:55:54 GMT Received: from [192.168.8.5] (/213.41.92.70) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 10 Mar 2020 03:55:54 -0700 Subject: Re: [patch part-II V2 08/13] tracing: Provide lockdep less trace_hardirqs_on/off() variants To: Thomas Gleixner , LKML Cc: x86@kernel.org, Steven Rostedt , Brian Gerst , Juergen Gross , Frederic Weisbecker References: <20200308222359.370649591@linutronix.de> <20200308222609.731890049@linutronix.de> From: Alexandre Chartre Organization: Oracle Corporation Message-ID: <07a50582-1c2f-7f45-c7dd-5ff9c2ff3052@oracle.com> Date: Tue, 10 Mar 2020 11:55:57 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20200308222609.731890049@linutronix.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9555 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 malwarescore=0 mlxscore=0 adultscore=0 suspectscore=0 bulkscore=0 spamscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003100072 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9555 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 lowpriorityscore=0 spamscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 suspectscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 malwarescore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003100073 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/8/20 11:24 PM, Thomas Gleixner wrote: > trace_hardirqs_on/off() is only partially safe vs. RCU idle. The tracer > core itself is safe, but the resulting tracepoints can be utilized by > e.g. BPF which is unsafe. > > Provide variants which do not contain the lockdep invocation so the lockdep > and tracer invocations can be split at the call site and placed properly. > > The new variants also do not use rcuidle as they are going to be called > from entry code after/before context tracking. > > Signed-off-by: Thomas Gleixner > --- > V2: New patch > --- > include/linux/irqflags.h | 4 ++++ > kernel/trace/trace_preemptirq.c | 23 +++++++++++++++++++++++ > 2 files changed, 27 insertions(+) > > --- a/include/linux/irqflags.h > +++ b/include/linux/irqflags.h > @@ -29,6 +29,8 @@ > #endif > > #ifdef CONFIG_TRACE_IRQFLAGS > + extern void __trace_hardirqs_on(void); > + extern void __trace_hardirqs_off(void); > extern void trace_hardirqs_on(void); > extern void trace_hardirqs_off(void); > # define trace_hardirq_context(p) ((p)->hardirq_context) > @@ -52,6 +54,8 @@ do { \ > current->softirq_context--; \ > } while (0) > #else > +# define __trace_hardirqs_on() do { } while (0) > +# define __trace_hardirqs_off() do { } while (0) > # define trace_hardirqs_on() do { } while (0) > # define trace_hardirqs_off() do { } while (0) > # define trace_hardirq_context(p) 0 > --- a/kernel/trace/trace_preemptirq.c > +++ b/kernel/trace/trace_preemptirq.c > @@ -19,6 +19,17 @@ > /* Per-cpu variable to prevent redundant calls when IRQs already off */ > static DEFINE_PER_CPU(int, tracing_irq_cpu); > > +void __trace_hardirqs_on(void) > +{ > + if (this_cpu_read(tracing_irq_cpu)) { > + if (!in_nmi()) > + trace_irq_enable(CALLER_ADDR0, CALLER_ADDR1); > + tracer_hardirqs_on(CALLER_ADDR0, CALLER_ADDR1); > + this_cpu_write(tracing_irq_cpu, 0); > + } > +} > +NOKPROBE_SYMBOL(__trace_hardirqs_on); > + Shouldn't trace_hardirqs_on() be updated to call __trace_hardirqs_on()? It's the same code except for the lockdep call. void trace_hardirqs_on(void) { __trace_hardirqs_on(); lockdep_hardirqs_on(CALLER_ADDR0); } EXPORT_SYMBOL(trace_hardirqs_on); NOKPROBE_SYMBOL(trace_hardirqs_on); > void trace_hardirqs_on(void) > { > if (this_cpu_read(tracing_irq_cpu)) { > @@ -33,6 +44,18 @@ void trace_hardirqs_on(void) > EXPORT_SYMBOL(trace_hardirqs_on); > NOKPROBE_SYMBOL(trace_hardirqs_on); > > +void __trace_hardirqs_off(void) > +{ > + if (!this_cpu_read(tracing_irq_cpu)) { > + this_cpu_write(tracing_irq_cpu, 1); > + tracer_hardirqs_off(CALLER_ADDR0, CALLER_ADDR1); > + if (!in_nmi()) > + trace_irq_disable(CALLER_ADDR0, CALLER_ADDR1); > + } > + > +} > +NOKPROBE_SYMBOL(__trace_hardirqs_off); > + Same comment here. alex. > void trace_hardirqs_off(void) > { > if (!this_cpu_read(tracing_irq_cpu)) { >