From: Masami Hiramatsu <mhiramat@kernel.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Aleksa Sarai <cyphar@cyphar.com>,
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Masami Hiramatsu <mhiramat@kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Shuah Khan <shuah@kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Brendan Gregg <bgregg@netflix.com>,
Christian Brauner <christian@brauner.io>,
Aleksa Sarai <asarai@suse.de>,
netdev@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v3 1/2] kretprobe: produce sane stack traces
Date: Sat, 3 Nov 2018 22:00:12 +0900 [thread overview]
Message-ID: <20181103220012.55ecd97e671c43e4959c8b62@kernel.org> (raw)
In-Reply-To: <20181102121307.32e99414@gandalf.local.home>
On Fri, 2 Nov 2018 12:13:07 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Fri, 2 Nov 2018 10:43:26 -0500
> Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> > > I'll hopefully have a prototype ready by plumbers.
> >
> > Why do we need multiple users? It would be a lot simpler if we could
> > just enforce a single user per fgraphed/kretprobed function (and return
> > -EBUSY if it's already being traced/probed).
>
> Because that means if function graph tracer is active, then you can't
> do a kretprobe, and vice versa. I'd really like to have it working for
> multiple users, then we could trace different graph functions and store
> them in different buffers. It would also allow for perf to use function
> graph tracer too.
Steve, how woul you allow multiple users on it? Something like this?
ret_trampoline_multiple(){
list_for_each(handler, &shadow_entry[i].handlers, list)
handler(shadow_entry[i]);
restore_retval_and_jump_to(shadow_entry[i].orig);
}
> > > And this too will require each architecture to probably change. As a
> > > side project to this, I'm going to try to consolidate the function
> > > graph code among all the architectures as well. Not an easy task.
> >
> > Do you mean implementing HAVE_FUNCTION_GRAPH_RET_ADDR_PTR for all the
> > arches? If so, I think have an old crusty patch which attempted to
> > that. I could try to dig it up if you're interested.
> >
>
> I'd like to have that, but it still requires some work. But I'd just
> the truly architecture dependent code be in the architecture (basically
> the asm code), and have the ability to move most of the duplicate code
> out of the archs.
I will also do that for kretprobe handlers.
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2018-11-03 13:00 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 8:35 [PATCH v3 0/2] kretprobe: produce sane stack traces Aleksa Sarai
2018-11-01 8:35 ` [PATCH v3 1/2] " Aleksa Sarai
2018-11-01 15:20 ` Masami Hiramatsu
2018-11-01 21:13 ` Aleksa Sarai
2018-11-02 3:04 ` Masami Hiramatsu
2018-11-02 4:37 ` Aleksa Sarai
2018-11-03 12:47 ` Masami Hiramatsu
2018-11-02 0:47 ` Steven Rostedt
2018-11-02 5:05 ` Aleksa Sarai
2018-11-02 6:59 ` Aleksa Sarai
2018-11-02 13:16 ` Steven Rostedt
2018-11-02 15:43 ` Josh Poimboeuf
2018-11-02 16:13 ` Steven Rostedt
2018-11-03 13:00 ` Masami Hiramatsu [this message]
2018-11-03 13:13 ` Steven Rostedt
2018-11-03 16:34 ` Masami Hiramatsu
2018-11-03 17:30 ` Steven Rostedt
2018-11-03 17:33 ` Steven Rostedt
2018-11-04 2:25 ` Masami Hiramatsu
2018-11-03 7:02 ` Aleksa Sarai
2018-11-04 11:59 ` Aleksa Sarai
2018-11-06 22:15 ` Steven Rostedt
2018-11-08 7:46 ` Aleksa Sarai
2018-11-08 8:04 ` Aleksa Sarai
2018-11-08 14:44 ` Josh Poimboeuf
2018-11-09 7:26 ` Masami Hiramatsu
2018-11-09 15:10 ` Aleksa Sarai
2018-11-09 7:15 ` Masami Hiramatsu
2018-11-09 15:06 ` Aleksa Sarai
2018-11-10 15:31 ` Masami Hiramatsu
2018-11-12 10:38 ` Aleksa Sarai
2018-11-03 13:23 ` Masami Hiramatsu
2018-11-02 7:58 ` Aleksa Sarai
2018-11-02 4:01 ` kbuild test robot
2018-11-01 8:35 ` [PATCH v3 2/2] trace: remove kretprobed checks Aleksa Sarai
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