linux-kernel - Re: [PATCH] tracing/selftests: Ignore __pfx

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Message-ID: <20230207135402.38f73bb6@gandalf.local.home>
Date:   Tue, 7 Feb 2023 13:54:02 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     LKML <linux-kernel@...r.kernel.org>,
        Linux Trace Kernel <linux-trace-kernel@...r.kernel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Shuah Khan <shuah@...nel.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] tracing/selftests: Ignore __pfx_ symbols in kprobe test

On Tue, 7 Feb 2023 13:51:47 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> From: "Steven Rostedt (Google)" <rostedt@...dmis.org>
> 
> The kprobe probepoint.tc test started failing because of the added __pfx_
> symbols that were added because of -fpatchable-function-entry=X,Y causing
> unwinders to see them as part of the previous functions. But kprobes can
> not be added on top of them. The selftest looks for tracefs_create_dir and
> picks it and the previous and following functions to add at their address.
> This caused it to include __pfx_tracefs_create_dir which is invalid to
> attach a kprobe to and caused the test to fail.
> 
> Fixes: 9f2899fe36a62 ("objtool: Add option to generate prefix symbols")
> Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>

This is assuming that kprobes can not be added on top of these. But another
solution could be to have kprobes just pick the function the __pfx_ is for.
Would that be a better solution?

-- Steve