Re: [PATCH net-next 0/2] bpf: add search pruning optimization and tests
From: David Miller
Date: Wed Oct 01 2014 - 21:31:20 EST
From: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Date: Mon, 29 Sep 2014 18:50:00 -0700
> patch #1 commit log explains why eBPF verifier has to examine some
> instructions multiple times and describes the search pruning optimization
> that improves verification speed for branchy programs and allows more
> complex programs to be verified successfully.
> This patch completes the core verifier logic.
>
> patch #2 adds more verifier tests related to branches and search pruning
>
> I'm still working on Andy's 'bitmask for stack slots' suggestion. It will be
> done on top of this patch.
>
> The current verifier algorithm is brute force depth first search with
> state pruning. If anyone can come up with another algorithm that demonstrates
> better results, we'll replace the algorithm without affecting user space.
>
> Note verifier doesn't guarantee that all possible valid programs are accepted.
> Overly complex programs may still be rejected.
> Verifier improvements/optimizations will guarantee that if a program
> was passing verification in the past, it will still be passing.
Series applied, thanks.
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