From: Masami Hiramatsu <mhiramat@kernel.org>
To: "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>,
linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/2] selftests/ftrace: Update multiple kprobes test for powerpc
Date: Thu, 29 Jun 2017 09:57:57 +0900 [thread overview]
Message-ID: <20170629095757.2f1fea73ad2e61ad08618e15@kernel.org> (raw)
In-Reply-To: <20170628184324.zpfe6f54jbhzxq5g@naverao1-tp.localdomain>
On Thu, 29 Jun 2017 00:13:24 +0530
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> wrote:
> On 2017/06/28 11:16PM, Masami Hiramatsu wrote:
> > > > diff --git
> > > > a/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc
> > > > b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc
> > > > new file mode 100644
> > > > index 0000000..d259031
> > > > --- /dev/null
> > > > +++ b/tools/testing/selftests/ftrace/test.d/kprobe/kprobe_eventname.tc
> > > > @@ -0,0 +1,28 @@
> > > > +#!/bin/sh
> > > > +# description: Kprobe event auto/manual naming
> > > > +
> > > > +disable_events
> > > > +echo > kprobe_events
> > > > +
> > > > +:;: "Add an event on function without name" ;:
> > > > +
> > > > +FUNC=`grep -m 10 " [tT] [^.]*$" /proc/kallsyms | tail -n 1 | cut -f 3 -d " "`
> > >
> > > On powerpc, this always ends up using a blacklisted function. So, I
> > > think we need a way to find a function that is not black listed.
> >
> > Hmm, if we increase the -m argument, like -m 100, is that still
> > in a blacklisted function?
>
> Yes, most of the initial symbols are exception vectors which are
> blacklisted.
Hmm, then how about this? :)
grep _stext -A 1000 | grep -m 10 " [tT] [^.]*$" /proc/kallsyms
>
> >
> > > However, one of the issues is that debugfs does not show all the address
> > > ranges that are blacklisted. I am coming up with a way to address that
> > > and will post patches once I have it working.
> >
> > Would you find that is only on powerpc or generic issue?
>
> I meant the address _ranges_ that are blacklisted such as the ones with
> __kprobes annotation and __entry_text and so on.
I see, but we can also check the address by comparing the address
of symbols, which also can be retrieved from kallsyms.
Since the test case is also applied to stable kernel, I don't want
to make it depending on some special kernel tweaks.
> >
> > >
> > > With those patches, we should be able to select symbols that are not
> > > blacklisted.
> >
> > Or, maybe we can use generic function, like "schedule" or "vfs_read"
> > etc.
>
> Yes, I think this will be good for the generic test, but may not help
> selecting a dot symbol on powerpc.
Right, and it depends on what gcc version and option is specified.
So, maybe we can skip the test if there is no such symbols.
I intended to test the symbols with some dot-suffix, but it seems
ppc64 has dot-started symbols, right? If there is no dot-suffixed
symbols, I think this test should skip the test case.
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2017-06-29 0:58 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-21 18:50 [PATCH 0/2] A couple of small updates/fixes for kprobes tracer Naveen N. Rao
2017-06-21 18:50 ` [PATCH 1/2] trace/kprobes: Sanitize derived event names Naveen N. Rao
2017-06-22 9:29 ` Masami Hiramatsu
2017-06-22 19:03 ` Naveen N. Rao
2017-06-23 17:30 ` Masami Hiramatsu
2017-06-21 18:50 ` [PATCH 2/2] selftests/ftrace: Update multiple kprobes test for powerpc Naveen N. Rao
2017-06-22 9:07 ` Masami Hiramatsu
2017-06-22 17:03 ` Naveen N. Rao
2017-06-23 17:30 ` Masami Hiramatsu
2017-06-24 11:06 ` Masami Hiramatsu
2017-06-28 9:28 ` Naveen N. Rao
2017-06-28 14:16 ` Masami Hiramatsu
2017-06-28 18:43 ` Naveen N. Rao
2017-06-29 0:57 ` Masami Hiramatsu [this message]
2017-06-29 13:08 ` Naveen N. Rao
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