The problem is that there's not much GDB can do with hand-coded
assembly functions.
However, GDB ought to be able to detect and stop that loop without any
of this. It seems to me that the problem is not two frames with the
same PC, but two frames with their PC "saved" in the same place - i.e.
GDB failing to figure out where the PC is saved. This is made a little
tricky in current versions of GDB, because the PC is normally unwound
using frame_pc_unwind (which doesn't tell us where it was saved, since
the interface doesn't assume it's a single normal register), and the
core code doesn't have a concept of a "PC register" any more.
Andrew, any idea on how to do this?