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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 16:28:11 +0100	[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

  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  1:28 [PATCH -tip v4 0/6] kprobes: introduce NOKPROBE_SYMBOL() and fixes crash bugs Masami Hiramatsu
2013-12-04  1:28 ` [PATCH -tip v4 1/6] kprobes: Prohibit probing on .entry.text code Masami Hiramatsu
2013-12-04  1:28 ` [PATCH -tip v4 2/6] kprobes: Introduce NOKPROBE_SYMBOL() macro for blacklist Masami Hiramatsu
2013-12-04  1:28 ` [PATCH -tip v4 3/6] [BUGFIX] kprobes/x86: Prohibit probing on debug_stack_* Masami Hiramatsu
2013-12-04  1:28 ` [PATCH -tip v4 4/6] [BUGFIX] x86: Prohibit probing on native_set_debugreg Masami Hiramatsu
2013-12-04  1:28 ` [PATCH -tip v4 5/6] [BUGFIX] x86: Prohibit probing on thunk functions and restore Masami Hiramatsu
2013-12-04  1:28 ` [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  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  8:45 ` Ingo Molnar
2013-12-04 23:27   ` 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 23:25           ` Masami Hiramatsu
2013-12-05 14:49     ` Frank Ch. Eigler
2013-12-06  6:12       ` Masami Hiramatsu
2013-12-06 19:07         ` Frank Ch. Eigler
2013-12-06 23:19           ` Masami Hiramatsu
2013-12-07  1:32             ` Frank Ch. Eigler
2013-12-07  2:34               ` Masami Hiramatsu

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