You need to use a debugger that will work at the assembly level and will allow you to step through individual assembly instructions.

See Section 8.6 of the gdb manual; this seems relevant.
http://sourceware.org/gdb/current/on...b_9.html#SEC64

There's also an apparently relevant section in the ddd documentation:
http://www.gnu.org/manual/ddd/html_m...el%20Debugging

RTFM!