[lttng-dev] Getting function names with lttng-ust-cyg-profile.so

[Mathieu Desnoyers]

We might want to investigate doing a side-program that gathers the
executables on the system, and lookup the symbols from the ELF. We could
save those in a bin/ subdirectory of a CTF trace. All we need is
instrumentation of the dynamic linker, and to know the executable names
associated with PIDs. There is a UST feature request for dynamic linker
instrumentation.

Thanks,

Mathieu

* Alexandre Montplaisir (alexmonthy at voxpopuli.im) wrote:
> Hi all,
> 
> I've recently started playing with liblttng-ust-cyg-profile.so (aka,
> getting UST events from -finstrument-functions), and I have to say it's
> pretty nifty! I haven't done any benchmarks, but it's certainly faster
> than the typical printf() that people use with it...
> 
> However, in the resulting trace, one only gets the addresses of the
> functions. I understand how it's relatively "easy" for the seasoned user
> to use nm or addr2line to get the actual function names, but would it
> possible - and how hard would it be - to have this information (function
> names) directly in the trace?
> 
> 
> I'm trying to leverage this feature in Eclipse TMF to display a call
> stack for such UST traces. And to be honest, displaying a call stack
> with only the function addresses is completely useless, we need the
> function names.
> 
> We could have the user import a text file (which he can generate with
> "nm appname > file.txt" for example). But then he needs the original
> binary, which he might not have. And that binary needs to be compiled
> with debugging symbols. If the function name information was already in
> the trace, it would make the user experience much better, and our job
> much easier! ;)
> 
> 
> Thoughts?
> 
> Thanks,
> Alex
> 
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-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com