Re: perf, kprobes: fuzzer generates huge number of WARNings

From: Alexei Starovoitov
Date: Tue Jul 07 2015 - 15:18:58 EST


On Tue, Jul 07, 2015 at 12:00:12AM -0400, Vince Weaver wrote:
>
> Well the BPF hack is in the fuzzer, not the kernel. And it's not really a
> hack, it just turned out to be a huge pain to figure out how to
> manually create a valid BPF program in conjunction with a valid kprobe
> event.

You mean automatically generating valid bpf program? That's definitely hard.
If you mean just few hardcoded programs then take them from samples or
from test_bpf ?

> I did have to sprinkle printks in the kprobe and bpf code to find out
> where various EINVAL returns were coming from, so potentially this is just
> a problem of printks happening where they shouldn't. I'll remove those
> changes and try to reproduce this tomorrow.

could you please elaborate on this further. Which EINVALs you talking about?

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