Re: failed to add c++ probe

From: Peter Zijlstra
Date: Thu Sep 22 2016 - 04:54:17 EST

On Wed, Sep 21, 2016 at 01:43:24PM +0900, Masami Hiramatsu wrote:
> On Wed, 21 Sep 2016 12:37:59 +0900
> Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote:

> Hmm, I found there are 3 issues in perf-probe to define event on C++ libs.
> 1) No mangle/demangle symbol support. This needs a) fix option parser to
> accept C++ method name correctly, b) mangle that method, and c) demangle
> it when we show the probe point.

I think we should also allow using the mangled name, supporting (de)mangling
is of course nice, but not required per-se. Esp. since there's more than
just C++ mangling. Having the mangling stuff as optional makes it a
convenience but still allows using this on other languages for which we
do not support the mangling.

> 2) @plt symbol should be skipped since the real function will be called(jumped)
> from plt, when searching probe point.
> 3) Event group name is including some characters which can not be used (e.g. "++").
> Thus we have to remove it or replace it with '_' or other alphabet.("PP"?)

What is the problem with the '+' character? Why cannot this be used?