[Bug translator/6594] investigate ftrace interface

[fche at redhat dot com]

------- Additional Comments From fche at redhat dot com  2008-10-02 16:56 -------
> > probably needs kernel changes for:
> > ... module-friendly ftrace registration api
> I think this should be done by simply exporting
> register/unregister_ftrace_function().

Hooking into the "dyn-ftrace" functionality seems more relevant,
since that is what we'd need to choose only subsets of kernel
functions to probe.  The register_ftrace_function widget seems
to be suited only for a separate abstract event source that traps\*all* function
entries.


> > ... and a data (argument) passing mechanism
> 
> Arguments passing is hard because of mcount implementation.
> It will give us just caller ip and callee ip.
> So, in the first phase, might we support only $caller and $callee in
> ftrace-based probe?

I was not talking about accessing contextual data registers via ftrace.
We'll have to work somewhat hard to make that work at all.  What I
was referring to was a callback void* parameter that allows us
to tell apart potentially multiple registrations -- like the kprobe*
pointer we get back from kprobe callbacks.


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=6594

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