BPF Single Step Debugging
=========================
Developers have long used single-step debugging
for some user-space tricky bugs. But for bpf programs
running inside the kernel, true single-step is not
really an option. Possible solutions would be:
(1). maybe we can run the bpf programs on a VM,
and we can single-step bpf program by repeatedly
freezing and waking up VMs.
(2). maybe we can resign bpf_prog_test_run()
interface to at least allow single steps
for programs in bpf_prog_test_run() environment.
(3). maybe we can simulate single steps in production
environment by attaching kprobes all instructions
in a program.
Each of the above approaches has some limitations.
Furthermore, source level single stepping is much more
preferred than optimized code (-O2) single stepping as the
former prints out in much user friendly formats.
We would like to examine the above three different options
as well as how far we are away from source level debugging
and what we could do about it.
-- Yonghong
