From: Ingo Molnar <mingo@kernel.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
Sandeepa Prabhu <sandeepa.prabhu@linaro.org>,
x86@kernel.org, lkml <linux-kernel@vger.kernel.org>,
"Steven Rostedt (Red Hat)" <rostedt@goodmis.org>,
systemtap@sourceware.org, "David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH -tip v4 0/6] kprobes: introduce NOKPROBE_SYMBOL() and fixes crash bugs
Date: Tue, 10 Dec 2013 15:28:00 -0000 [thread overview]
Message-ID: <20131210152811.GA1195@gmail.com> (raw)
In-Reply-To: <52A137B6.6030307@hitachi.com>
* Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:
> (2013/12/05 19:21), Ingo Molnar wrote:
> >
> > * Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:
> >
> >>> So we need both a maintainable and a sane/safe solution, and I'd
> >>> like to apply the whole thing at once and be at ease that the
> >>> solution is round. We should have done this years ago.
> >>
> >> For the safeness of kprobes, I have an idea; introduce a whitelist
> >> for dynamic events. AFAICS, the biggest unstable issue of kprobes
> >> comes from putting *many* probes on the functions called from
> >> tracers.
> >
> > If the number of 'noprobe' annotations is expected to explode then
> > maybe another approach should be considered.
>
> No, since this is a "quantitative" issue, the annotation helps us.
>
> > For example in perf we detect recursion. Could kprobes do that and
> > detect hitting a probe while running kprobes code, and ignore it [do
> > an early return]?
>
> Yes, the kprobe itself already has recursion detector and it rejects
> calling handler.
So why are annotations needed at all? What can happen if an annotation
is missing and a piece of code is probed which is also used by the
kprobes code internally - do we crash, lock up, misbehave or handle it
safely?
Thanks,
Ingo
next prev parent reply other threads:[~2013-12-10 15:28 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-04 1:34 Masami Hiramatsu
2013-12-04 1:34 ` [PATCH -tip v4 1/6] kprobes: Prohibit probing on .entry.text code Masami Hiramatsu
2013-12-04 1:35 ` [PATCH -tip v4 2/6] kprobes: Introduce NOKPROBE_SYMBOL() macro for blacklist Masami Hiramatsu
2013-12-04 1:36 ` [PATCH -tip v4 3/6] [BUGFIX] kprobes/x86: Prohibit probing on debug_stack_* Masami Hiramatsu
2013-12-04 1:36 ` [PATCH -tip v4 4/6] [BUGFIX] x86: Prohibit probing on native_set_debugreg Masami Hiramatsu
2013-12-04 1:36 ` [PATCH -tip v4 6/6] [RFC] kprobes/x86: Call exception handlers directly from do_int3/do_debug Masami Hiramatsu
2013-12-04 2:39 ` Steven Rostedt
2013-12-11 13:31 ` Jiri Kosina
2013-12-12 4:40 ` Masami Hiramatsu
2013-12-12 9:59 ` Jiri Kosina
2013-12-12 10:31 ` Masami Hiramatsu
2013-12-04 1:36 ` [PATCH -tip v4 5/6] [BUGFIX] x86: Prohibit probing on thunk functions and restore Masami Hiramatsu
2013-12-04 2:54 ` [PATCH -tip v4 0/6] kprobes: introduce NOKPROBE_SYMBOL() and fixes crash bugs Sandeepa Prabhu
2013-12-04 7:39 ` Masami Hiramatsu
2013-12-04 8:46 ` Sandeepa Prabhu
2013-12-04 23:32 ` Masami Hiramatsu
2013-12-04 8:46 ` Ingo Molnar
2013-12-04 23:28 ` Masami Hiramatsu
2013-12-05 10:21 ` Ingo Molnar
2013-12-06 2:34 ` Masami Hiramatsu
2013-12-10 15:28 ` Ingo Molnar [this message]
2013-12-11 2:12 ` Masami Hiramatsu
2013-12-11 13:34 ` Ingo Molnar
2013-12-12 6:02 ` Masami Hiramatsu
2013-12-12 14:03 ` Ingo Molnar
2013-12-12 20:42 ` Josh Stone
2013-12-13 5:34 ` Masami Hiramatsu
2013-12-13 6:06 ` Masami Hiramatsu
2013-12-16 10:53 ` Masami Hiramatsu
2013-12-05 13:08 ` Sandeepa Prabhu
2013-12-06 6:23 ` Masami Hiramatsu
2013-12-06 6:54 ` Sandeepa Prabhu
2013-12-06 23:26 ` Masami Hiramatsu
2013-12-05 14:49 ` Frank Ch. Eigler
2013-12-06 6:13 ` Masami Hiramatsu
2013-12-06 19:08 ` Frank Ch. Eigler
2013-12-06 23:19 ` Masami Hiramatsu
2013-12-07 1:33 ` Frank Ch. Eigler
2013-12-07 2:35 ` Masami Hiramatsu
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