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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 20622C6778A for ; Tue, 3 Jul 2018 22:30:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C822224758 for ; Tue, 3 Jul 2018 22:30:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C822224758 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753471AbeGCWay (ORCPT ); Tue, 3 Jul 2018 18:30:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:57202 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753410AbeGCWav (ORCPT ); Tue, 3 Jul 2018 18:30:51 -0400 Received: from gandalf.local.home (cpe-66-24-56-78.stny.res.rr.com [66.24.56.78]) (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 AA15123C49; Tue, 3 Jul 2018 22:30:50 +0000 (UTC) Date: Tue, 3 Jul 2018 18:30:48 -0400 From: Steven Rostedt To: Mathieu Desnoyers , Francis Deslauriers Cc: Masami Hiramatsu , Peter Zijlstra , linux-kernel , Linus Torvalds Subject: Re: [PATCH 2/2] kprobe: fix: Add ftrace_ops_assist_func to kprobe blacklist Message-ID: <20180703183048.1eeeef4a@gandalf.local.home> In-Reply-To: <20180317102211.a648f26ae0d5a53d95c63022@kernel.org> References: <1500044315-9508-1-git-send-email-francis.deslauriers@efficios.com> <1500044315-9508-3-git-send-email-francis.deslauriers@efficios.com> <20170714142900.1c91949c@gandalf.local.home> <20180316112517.66bdd85a@gandalf.local.home> <229385456.11580.1521217739037.JavaMail.zimbra@efficios.com> <20180316124134.30fa47d5@gandalf.local.home> <20180316124840.3e83bbec@gandalf.local.home> <1577244734.11604.1521222781948.JavaMail.zimbra@efficios.com> <20180317091334.55f1fc325c26deaa4d4a4d19@kernel.org> <20180317102211.a648f26ae0d5a53d95c63022@kernel.org> X-Mailer: Claws Mail 3.16.0 (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 Mathieu and Francis, Looking back, this thread never got further. Would Masami's patch work for you? -- Steve On Sat, 17 Mar 2018 10:22:11 +0900 Masami Hiramatsu wrote: > On Sat, 17 Mar 2018 09:13:34 +0900 > Masami Hiramatsu wrote: > > > On Fri, 16 Mar 2018 13:53:01 -0400 (EDT) > > Mathieu Desnoyers wrote: > > > > > ----- On Mar 16, 2018, at 12:48 PM, rostedt rostedt@goodmis.org wrote: > > > > > > > On Fri, 16 Mar 2018 12:41:34 -0400 > > > > Steven Rostedt wrote: > > > > > > > >> Yes, kprobes are dangerous. I'm not saying it shouldn't be fixed, I'm > > > >> saying that I don't have time to fix it now, but would be happy to > > > >> accept patches if someone else does so. > > > > > > > > And looking at what I replied before for the original patch. It would > > > > probably be a good idea to blacklist directories. Like we do with > > > > function tracing. We probably should black list both kernel/tracing and > > > > kernel/events from being probed. > > > > > > > > Did this come up at plumbers? You were there too, I don't remember > > > > discussing it there. > > > > > > I don't remember this coming up last Plumbers nor KS neither, given > > > that we were focused on other topics. > > > > > > Would the general approach you envision be based on emitting all code > > > generated by compilation of all objects under kernel/tracing and > > > kernel/events into a specific "nokprobes" text section of the kernel ? > > > Perhaps we could create a specific linker scripts for those directories, > > > or do you have in mind a neater way to do this ? > > > > .kprobes.text section still exists. As I pointed in previous mail, I don't > > think we have to put all those code into that section. But if you want, > > it is acceptable to have a kconfig which push most of those ftrace related > > code into .kprobes.text section. > > Or, we can check it by ftrace_location_range() as below patch. > > Note that as a side-effect, we can not trace functions in trace_kprobe.c > anymore, and this means it is hard to me to make a testcase of kprobe events. > It was the easiest (and maintainable) way to make test cases... sigh. > > ----- > tracing: kprobes: Prohibit probing on notrace function > > From: Masami Hiramatsu > > Prohibit kprobe-events probing on notrace function. > Since probing on the notrace function can cause recursive > event call. In most case those are just skipped, but > in some case it falls into infinit recursive call. > > Signed-off-by: Masami Hiramatsu > --- > kernel/trace/trace_kprobe.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c > index 5ce9b8cf7be3..7404b012e51a 100644 > --- a/kernel/trace/trace_kprobe.c > +++ b/kernel/trace/trace_kprobe.c > @@ -487,6 +487,23 @@ disable_trace_kprobe(struct trace_kprobe *tk, struct trace_event_file *file) > return ret; > } > > +#ifdef CONFIG_KPROBES_ON_FTRACE > +static bool within_notrace_func(struct trace_kprobe *tk) > +{ > + unsigned long offset, size, addr; > + > + addr = kallsyms_lookup_name(trace_kprobe_symbol(tk)); > + addr += trace_kprobe_offset(tk); > + > + if (!kallsyms_lookup_size_offset(addr, &size, &offset)) > + return true; /* Out of range. */ > + > + return !ftrace_location_range(addr - offset, addr - offset + size); > +} > +#else > +#define within_notrace_func(tk) (false) > +#endif > + > /* Internal register function - just handle k*probes and flags */ > static int __register_trace_kprobe(struct trace_kprobe *tk) > { > @@ -495,6 +512,12 @@ static int __register_trace_kprobe(struct trace_kprobe *tk) > if (trace_probe_is_registered(&tk->tp)) > return -EINVAL; > > + if (within_notrace_func(tk)) { > + pr_warn("Could not probe notrace function %s\n", > + trace_kprobe_symbol(tk)); > + return -EINVAL; > + } > + > for (i = 0; i < tk->tp.nr_args; i++) > traceprobe_update_arg(&tk->tp.args[i]); > >