netdev - Re: [PATCH] bpf: optimize constant blinding

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Message-ID: <CAADnVQLp+N8pYTgmgEGfoubqKrWrnuTBJ9z2qc1rB6+04WfgHA@mail.gmail.com>
Date:   Wed, 12 Jun 2019 07:47:36 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Jiong Wang <jiong.wang@...ronome.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>
Subject: Re: [PATCH] bpf: optimize constant blinding

On Wed, Jun 12, 2019 at 4:32 AM Naveen N. Rao
<naveen.n.rao@...ux.vnet.ibm.com> wrote:
>
> Currently, for constant blinding, we re-allocate the bpf program to
> account for its new size and adjust all branches to accommodate the
> same, for each BPF instruction that needs constant blinding. This is
> inefficient and can lead to soft lockup with sufficiently large
> programs, such as the new verifier scalability test (ld_dw: xor
> semi-random 64 bit imms, test 5 -- with net.core.bpf_jit_harden=2)

Slowdown you see is due to patch_insn right?
In such case I prefer to fix the scaling issue of patch_insn instead.
This specific fix for blinding only is not addressing the core of the problem.
Jiong,
how is the progress on fixing patch_insn?