Here are some pointers https://wiki.python.org/moin/DebuggingWithGdb 1.5k
http://www.scipy-lectures.org/advanced/debugging/#debugging-segmentation-faults-using-gdb 681
Generally, you will want to insert a breakpoint in gdb with the C++ side function name or file + line number. And then you can step through line by line with the keys n or s