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From: Nam Cao <namcao@linutronix.de>
To: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>, naveen@kernel.org,
	anil.s.keshavamurthy@intel.com, davem@davemloft.net,
	linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org,
	john.ogness@linutronix.de
Subject: Re: kprobe on local function
Message-ID: <20250129063916.07WPgeQD@linutronix.de>
References: <20250122075939.qw7HsuMd@linutronix.de>
 <20250122172936.09bc8c9a@gandalf.local.home>
 <20250123104842.92336327f898e546c5b67536@kernel.org>
 <20250123024224.d0h8d4HV@linutronix.de>
 <20250125011655.449075f32f50de6fa7ff20b8@kernel.org>
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In-Reply-To: <20250125011655.449075f32f50de6fa7ff20b8@kernel.org>

On Sat, Jan 25, 2025 at 01:16:55AM +0900, Masami Hiramatsu wrote:
> Now what you could know is that the kernel does not call the
> "rt_mutex_slowunlock" symbol and it may call another copied symbol. That's
> a good to know right?
> 
> Note that this in-kernel kretprobe API is a low-layer API, so that user is
> responsible for controlling it carefully. This kretprobe API itself does NOT
> know which copy of the optimized symbols are used.
> (there could be inlined instance too)
> 
> If you need to know how many copies are generated or inlined, you need to
> use the debuginfo as "perf probe" tool does, which can not handled by the
> kernel itself because it is too big to be loaded. That is why I made the
> "perf probe" as an external tool.

Got it, thanks so much for the information!

Best regards,
Nam