From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 53010 invoked by alias); 7 Jul 2016 19:58:48 -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 52985 invoked by uid 89); 7 Jul 2016 19:58:47 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.2 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=dave.long@linaro.org, sk:davelo, U*dave.long, sk:dave.lo 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; Thu, 07 Jul 2016 19:58:36 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (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 A182B3F729; Thu, 7 Jul 2016 19:58:35 +0000 (UTC) Received: from fche.csb (unused [10.10.52.236] (may be forged)) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u67JwZEV013837; Thu, 7 Jul 2016 15:58:35 -0400 Received: by fche.csb (Postfix, from userid 2569) id 07C9058433; Thu, 7 Jul 2016 15:58:37 -0400 (EDT) To: David Long Cc: Pratyush Anand , William Cohen , systemtap@sourceware.org, Mark Brown , Jeremy Linton , David Smith Subject: Re: exercising current aarch64 kprobe support with systemtap 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> From: fche@redhat.com (Frank Ch. Eigler) Date: Thu, 07 Jul 2016 19:58:00 -0000 In-Reply-To: <577EA7EE.2070607@linaro.org> (David Long's message of "Thu, 7 Jul 2016 15:05:18 -0400") Message-ID: User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SW-Source: 2016-q3/txt/msg00027.txt.bz2 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. >> [...] > It sounds like the only fix would be to expand the blacklist to any > function that could be called in a debug exception-handling context? [...] The kernel maintains its own blacklist by means of designating some low-level functions with the "__kprobes" attribute. That protects those regions of code from "perf probe"-directed kprobes too. - FChE