Get backtrace at PLT and stepi into PLT

[Thinker Li]

Daniel Jacobowitz writes:
 > On Tue, Jul 21, 2009 at 10:57:06AM +0800, Thinker Li wrote:
 > > You can not do backtrace when you stop at PLT with GDB.
 > > arm_stub_unwind_sniffer create a frame with NORMAL_FRAME type for
 > > PLT.  But, when we do backtrace, get_prev_frame() will check if
 > > this frame inside_entry_func.  Since we can not found any symbol for
 > > PLT, it:s func address is 0, and entry_point_address() is also 0 if
 > > symfile_objfile is NULL (no main symbol table).  It makes problem on
 > > backtracing.
 > 
 > Thanks, that's much clearer.  That's where the bug is.  An unknown
 > function address should not be inside_entry_func.
Is it possible that entry point of an program is 0?
Maybe, we should change interface of entry_point_address() to indicate
an unknown address.

Do you have any suggestion?