linux-kernel - kprobe on local function

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Message-ID: <20250122075939.qw7HsuMd@linutronix.de>
Date: Wed, 22 Jan 2025 08:59:39 +0100
From: Nam Cao <namcao@...utronix.de>
To: naveen@...nel.org, anil.s.keshavamurthy@...el.com, davem@...emloft.net,
	mhiramat@...nel.org, linux-kernel@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org
Cc: john.ogness@...utronix.de
Subject: kprobe on local function

Hi,

I installed a kretprobe on the function "rt_mutex_slowunlock". Although the
function is called, the probe is never hit.

The reason is because there are 3 copies of rt_mutex_slowunlock() in
vmlinux (at least for x86 defconfig + CONFIG_PREEMPT_RT). But probe point
is only installed in 1 copy.

Is this considered a bug? Or is kprobe not intended to be used for local
function? Should we modify kprobe to support such cases?

Best regards,
Nam