From: Josef Bacik <[email protected]> Date: Tue, 31 Oct 2017 11:45:55 -0400
> v1->v2: > - moved things around to make sure that bpf_override_return could really only > be > used for an ftrace kprobe. > - killed the special return values from trace_call_bpf. > - renamed pc_modified to bpf_kprobe_state so bpf_override_return could tell if > it was being called from an ftrace kprobe context. > - reworked the logic in kprobe_perf_func to take advantage of > bpf_kprobe_state. > - updated the test as per Alexei's review. > > A lot of our error paths are not well tested because we have no good way of > injecting errors generically. Some subystems (block, memory) have ways to > inject errors, but they are random so it's hard to get reproduceable results. > > With BPF we can add determinism to our error injection. We can use kprobes > and > other things to verify we are injecting errors at the exact case we are trying > to test. This patch gives us the tool to actual do the error injection part. > It is very simple, we just set the return value of the pt_regs we're given to > whatever we provide, and then override the PC with a dummy function that > simply > returns. > > Right now this only works on x86, but it would be simple enough to expand to > other architectures. Thanks, This appears to moreso target the tracing tree than the networking tree. Let me know if that's not the case and I should be the one intergrating these changes. Thanks.
