From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 51416 invoked by alias); 3 Aug 2016 14:51:22 -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 51407 invoked by uid 89); 3 Aug 2016 14:51:22 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.1 required=5.0 tests=BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=evening, Anand, anand, el1 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 03 Aug 2016 14:51:11 +0000 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9663B85541; Wed, 3 Aug 2016 14:51:10 +0000 (UTC) Received: from [10.13.129.231] (dhcp129-231.rdu.redhat.com [10.13.129.231]) by int-mx09.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u73Ep93R005513; Wed, 3 Aug 2016 10:51:10 -0400 Subject: Re: exercising current aarch64 kprobe support with systemtap To: 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> Cc: David Long , systemtap@sourceware.org, Mark Brown , Jeremy Linton , David Smith , "Frank Ch. Eigler" From: William Cohen Message-ID: <5d70cfba-bfda-9887-464f-52bde9b99b01@redhat.com> Date: Wed, 03 Aug 2016 14:51:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.2.0 MIME-Version: 1.0 In-Reply-To: <20160803131302.GC18785@localhost.localdomain> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2016-q3/txt/msg00115.txt.bz2 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