ps RSS measurement is pretty good for a start (although note in a forked process, shared copy-on-write pages are both reported as RSS for both the parent and child process).

top reports this as RES.

IIRC, debugging information is in a separate part of the process, so it's not loaded until it's used. Does that make it free? Probably not quite, but the kernel can ignore it until the process (presumably via its debugger) looks at it.