From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 8487 invoked by alias); 3 Aug 2016 15:11:10 -0000 Mailing-List: contact systemtap-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: systemtap-owner@sourceware.org Received: (qmail 8463 invoked by uid 89); 3 Aug 2016 15:11:09 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 spammy=reminder, cohen, Cohen, tweak X-HELO: mail-qt0-f178.google.com Received: from mail-qt0-f178.google.com (HELO mail-qt0-f178.google.com) (209.85.216.178) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Wed, 03 Aug 2016 15:10:57 +0000 Received: by mail-qt0-f178.google.com with SMTP id 52so145120377qtq.3 for ; Wed, 03 Aug 2016 08:10:57 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:subject:to:references:cc:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding; bh=ST6rMsYLLUXmtKfwxszXjFqcjqNVS1kXMfWp6p6jJOo=; b=XJkXufW8g/MYLDHMUlqWcggs/7S1sWDlKIHcSdZjH4MDqotDWHKRjsu5dkY40rFfuK BsuhuhN35zObE6q2tA17cCKyoMUb6T+Y0sk6a4ZdlatirvodYp6221HZEVHm6a71UVKa CcjHMdMH9tEJ8YXOJQ4Oce4Vc2yrLe6OK2kr0fQwqXmopTi2QRIcDgd24Lm5L//A3CnQ hZ38H5iielZKKg/5ZEe4pAd+aOpysOKeY84XoMQN0M8gRoCFjzc7VtS3M1EhAa204KLu 8cnMphE9tCKIZOB+H3/YglIzugysQc3s6DJooTM5ow70sLvDIXogMPo2qF4coPUg965P ECKw== X-Gm-Message-State: AEkoouvDvBY7okjDkvHsmKSm0IQT5sBkxzbp9pEOUxEuty2tHo0Wb2K+OBVQkV8PV3Cj+I0h X-Received: by 10.237.39.34 with SMTP id n31mr357381qtd.55.1470237055377; Wed, 03 Aug 2016 08:10:55 -0700 (PDT) Received: from [192.168.0.119] (c-73-16-204-72.hsd1.nh.comcast.net. [73.16.204.72]) by smtp.googlemail.com with ESMTPSA id e68sm1547267qkf.31.2016.08.03.08.10.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Aug 2016 08:10:54 -0700 (PDT) Subject: Re: exercising current aarch64 kprobe support with systemtap To: William Cohen , Pratyush Anand References: <8f40d0b9-5550-92f9-d1c5-8769f52304c0@redhat.com> <576B5501.1030106@linaro.org> <576C29E1.8060805@linaro.org> <0a594132-796b-779d-b473-a06c0f3e8ae8@redhat.com> <20160627141840.GB8139@dhcppc9> <577EA7EE.2070607@linaro.org> <20160803131302.GC18785@localhost.localdomain> <5d70cfba-bfda-9887-464f-52bde9b99b01@redhat.com> Cc: systemtap@sourceware.org, Mark Brown , Jeremy Linton , David Smith , "Frank Ch. Eigler" From: David Long Message-ID: <57A20975.4090809@linaro.org> Date: Wed, 03 Aug 2016 15:11:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <5d70cfba-bfda-9887-464f-52bde9b99b01@redhat.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-SW-Source: 2016-q3/txt/msg00116.txt.bz2 On 08/03/2016 10:51 AM, William Cohen wrote: > On 08/03/2016 09:13 AM, Pratyush Anand wrote: >> On 07/07/2016:03:58:37 PM, Frank Ch. Eigler wrote: >>> David Long writes: >>> >>>> [...] >>>>> - bug_handler() calls report_bug() which calls __warn() >>>>> - __warn() does lot of pr_warn() which invokes print_worker_info() >>>>> where we have a kprobe instrumented. >>>>> - Therefore, we are encountering this issue. >> >> Hi Will, >> >> Can you please cross-check if following branch works perfectly with >> kprobes_onthefly.exp and other systemtap tests. >> >> https://github.com/pratyushanand/linux/tree/uprobe/upstream_arm64_devel_v1.1 >> >> Following patch in above branch should solve this issue. >> https://github.com/pratyushanand/linux/commit/d0dcc6477f1279ab0bd99aefc30efdecb16c586e >> >> However, I am not yet sure that above modification could be the best solution, >> so discussing at arm kernel list. >> >> ~Pratyush >> > > Hi Pratyush, > > I am setting up a machine with the locally built kernel and systemtap to see if the problem is resolved. I hope to have some results by this evening. > > Could there be a better way to handle the "Unexpected kernel single-step exception at EL1"? Getting stuck in a loop endlessly quickly printing out that message isn't very helpful. Maybe use pr_warn_ratelimited instead of pr_warn. > > -Will > Just a reminder that the latest kprobes patches are on the end of the for-next/kprobes branch in the: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git repo. There's at least one more tweak to that (removing jprobe stack copy) coming up shortly. Thanks, -dl