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From: Steven Rostedt <rostedt@goodmis.org>
To: Andrea Righi <righi.andrea@gmail.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	peterz@infradead.org,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/2] kprobes: Fix kretprobe incorrect stacking order problem
Date: Mon, 7 Jan 2019 14:59:18 -0500	[thread overview]
Message-ID: <20190107145918.407b851b@gandalf.local.home> (raw)
In-Reply-To: <20190107195209.GB5966@xps-13>

On Mon, 7 Jan 2019 20:52:09 +0100
Andrea Righi <righi.andrea@gmail.com> wrote:

> > Ug, kretprobe calls spinlocks in the callback? I wonder if we can
> > remove them.
> > 
> > I'm guessing this is a different issue than the one that this patch
> > fixes. This sounds like we are calling kretprobe from kretprobe?
> > 
> > -- Steve  
> 
> kretprobe_trampoline()
>   -> trampoline_handler()
>     -> kretprobe_hash_lock()
>       -> raw_spin_lock_irqsave()  
> 
> If we put a kretprobe to raw_spin_lock_irqsave() it looks like
> kretprobe is going to call kretprobe...

Right, but we should be able to add some recursion protection to stop
that. I have similar protection in the ftrace code.

-- Steve


  reply	other threads:[~2019-01-07 19:59 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-07 13:31 [PATCH 0/2] kprobes: Fix kretprobe incorrect stacking order problem Masami Hiramatsu
2019-01-07 13:32 ` [PATCH 1/2] x86/kprobes: Verify stack frame on kretprobe Masami Hiramatsu
2019-01-07 13:32 ` [PATCH 2/2] kprobes: Mark ftrace mcount handler functions nokprobe Masami Hiramatsu
2019-01-07 14:55   ` Andrea Righi
2019-01-07 17:29     ` Steven Rostedt
2019-01-08  2:41       ` Masami Hiramatsu
2019-01-08  2:40     ` Masami Hiramatsu
2019-01-07 17:23   ` kbuild test robot
2019-01-07 17:38   ` kbuild test robot
2019-01-07 17:28 ` [PATCH 0/2] kprobes: Fix kretprobe incorrect stacking order problem Andrea Righi
2019-01-07 18:34 ` Andrea Righi
2019-01-07 19:27   ` Steven Rostedt
2019-01-07 19:52     ` Andrea Righi
2019-01-07 19:59       ` Steven Rostedt [this message]
2019-01-07 21:19         ` Andrea Righi
2019-01-07 21:28           ` Steven Rostedt
2019-01-07 21:34             ` Andrea Righi
2019-01-08  2:56               ` Masami Hiramatsu

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