Re: [PATCH] bpf: don't verify classic bpfs

[Thomas Monjalon <thomas@monjalon.net>]

16/05/2024 11:36, Konstantin Ananyev:
> 
> > On Sun, 12 May 2024 08:55:45 +0300
> > Yoav Winstein <yoav.w@claroty.com> wrote:
> > 
> > > When classic BPFs with lots of branching instructions are compiled,
> > > __rte_bpf_bpf_validate runs way too slow. A simple bpf such as:
> > > 'ether host a0:38:6d:af:17:eb or b3:a3:ff:b6:c1:ef or ...' 12 times
> > >
> > > results in ~1 minute of bpf validation.
> > > This patch makes __rte_bpf_bpf_validate be aware of bpf_prm originating
> > > from classic BPF, allowing to safely skip over the validation.
> > >
> > > Signed-off-by: Yoav Winstein <yoav.w@claroty.com>
> > > ---
> > 
> > No.
> > Wallpapering over a performance bug in the BPF library is not
> > the best way to handle this. Please analyze the problem in the BPF
> > library; it should be fixed there.
> 
> +1
> Blindly disabling verification for all cBPFs is the worst possible option here.
> We need at least try to understand what exactly causing such slowdown.

+1

You didn't mention it is also breaking ABI compatibility.