linux-kernel - Re: [PATCH v3] tracepoint: Fix CFI failures with tp_sub

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Message-ID: <20230411131423.37b001f7@gandalf.local.home>
Date:   Tue, 11 Apr 2023 13:14:37 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        linux-kernel@...r.kernel.org,
        "Jose E . Marchesi" <jose.marchesi@...cle.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v3] tracepoint: Fix CFI failures with tp_sub_func

On Sat, 8 Apr 2023 23:03:44 +0900
Masami Hiramatsu (Google) <mhiramat@...nel.org> wrote:

> I think we need another stub function similar to the original patch, because
> the __tracestub_* functions are usually not called back. Even if I enabled
> the static key to enable the stub callback, if user sets another callback
> handler to the tracepoint (e.g. enable trace event on it), the __tracestub_*
> function is not called anymore.
> 
> Thus I think we just pick this version and add another patch to introduce
> __probestub_* functions in macro, and fprobe on it. This new stub function is
> something like the original one so that it doesn't break CFI. And it will be
> registered to tracepoint when the new fprobe based dynamic event is enabled.
> 

If we are going to add *another* stub, then no, I don't want to use it. But
I don't see why we can't use one stub for both?

What's the issue you are having?

-- Steve