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From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@kernel.org>, Andi Kleen <ak@linux.intel.com>,
	Ananth N Mavinakayanahalli <ananth@in.ibm.com>,
	Sandeepa Prabhu <sandeepa.prabhu@linaro.org>,
	Frederic Weisbecker <fweisbec@gmail.com>,
	x86@kernel.org, lkml <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ingo Molnar <mingo@redhat.com>,
	systemtap@sourceware.org, "H. Peter Anvin" <hpa@zytor.com>,
	Sasha Levin <sasha.levin@oracle.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Seiji Aguchi <seiji.aguchi@hds.com>,
	"David S. Miller" <davem@davemloft.net>
Subject: Re: [PATCH -tip v4 6/6] [RFC] kprobes/x86: Call exception handlers directly from do_int3/do_debug
Date: Tue, 3 Dec 2013 21:39:04 -0500	[thread overview]
Message-ID: <20131203213904.5ff1794c@gandalf.local.home> (raw)
In-Reply-To: <20131204012856.22118.91079.stgit@kbuild-fedora.novalocal>

On Wed, 04 Dec 2013 01:28:56 +0000
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote:

> To avoid a kernel crash by probing on lockdep code, call
> kprobe_int3_handler and kprobe_debug_handler directly
> from do_int3 and do_debug. Since there is a locking code
> in notify_die, lockdep code can be invoked. And because
> the lockdep involves printk() related things, theoretically,
> we need to prohibit probing on much more code...
> 
> Anyway, most of the int3 handlers in the kernel are already
> called from do_int3 directly, e.g. ftrace_int3_handler,
> poke_int3_handler, kgdb_ll_trap. Actually only
> kprobe_exceptions_notify is on the notifier_call_chain.
> 
> So I think this is not a crazy thing.

What? Oh, yeah. No, using notifiers in int3 handler is the crazy
thing ;-)

Hmm, if there's no users of the int3 notifier, should we just remove it?

-- Steve

  reply	other threads:[~2013-12-04  2:39 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 [this message]
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
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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