Subject: Re: [RFC][PATCH 0/4] ftrace: Use -mfentry when supported (this is
 for x86_64 right now)
From: Steven Rostedt <rostedt@goodmis.org>
To: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Andi Kleen <andi@firstfloor.org>
In-Reply-To: <4D5D1672.6070206@hitachi.com>
References: <20110209200249.111932716@goodmis.org>
	 <4D5D1672.6070206@hitachi.com>
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Date: Thu, 17 Feb 2011 08:18:23 -0500
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On Thu, 2011-02-17 at 21:37 +0900, Masami Hiramatsu wrote:

> Oops! with this change, current kprobes might not be able to probe
> the entry of functions, because that is always reserved by ftrace!
> I think we need to have some new interface for replacing each other
> safely...

Good point. I suspect that this wont be ready till .40 anyway. When I
get a chance to work more an this, I'll also include patches where if
-mfentry is activated kprobes will just hook to the mcount caller
instead. Or ftrace itself :)

I'm also working on making the function tracer a bit more flexible. That
is, to let multiple clients control the dynamic trace instead of just
one big global one.

-- Steve


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