Landed during the 3.6 beta1 sprint:
https://hg.python.org/cpython/rev/d622dbd71f2b

Thanks all for the preliminary tasks! I rebuilt the patch from first principles, reusing large parts of Jesús' work, as well as work by Dave and Nikhil.

Things deliberately left out for simplicity:
- ustack helpers, I have no way of testing them at this point since
they are Solaris-specific, don't work on macOS or Linux
- PyFrameObject * in function__entry/function__return, this is
SystemTap-specific and won't compile with DTrace
- SPARC support
- dynamic tracing
- sys module dtrace facility introspection (as described in the documentation, there's facilities in both Linux and macOS to do the same thing)

All of those might be added later.

I also left out instance new/delete probes for now since I had problems making them stable. We might still be able to squeeze them in if we're quick about it.

Dave, if you have an idea how to integrate your FrameObject pointer in a way that compiles for DTrace, too, this is the time to speak up :)

Jesús, if you'd like to add the ustack helper back in a separate patch and add to the documentation how this can be tested, that's great, too. I just didn't feel comfortable committing code myself that I have no way of testing, especially that it required more code (the offsets, including the generated .h here and there, etc.).