netdev - Re: [PATCH bpf-next v3 03/16] bpf: verifier support JMP32

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Message-ID: <3e7a469a-8707-9d51-e1a9-0d57a489fcf7@iogearbox.net>
Date:   Sat, 26 Jan 2019 01:36:22 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jiong Wang <jiong.wang@...ronome.com>, ast@...nel.org
Cc:     netdev@...r.kernel.org, oss-drivers@...ronome.com
Subject: Re: [PATCH bpf-next v3 03/16] bpf: verifier support JMP32

On 01/25/2019 01:10 AM, Jiong Wang wrote:
> This patch teach verifier about the new BPF_JMP32 instruction class.
> Verifier need to treat it similar as the existing BPF_JMP class.
> A BPF_JMP32 insn needs to go through all checks that have been done on
> BPF_JMP.
> 
> Also, verifier is doing runtime optimizations based on the extra info
> conditional jump instruction could offer, especially when the comparison is
> between constant and register that the value range of the register could be
> improved based on the comparison results. These code are updated
> accordingly.
> 
> Acked-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
> Signed-off-by: Jiong Wang <jiong.wang@...ronome.com>

Series looks good to me, but if I spot this correctly one thing that has
not been addressed here is proper rebase on top of Jakub's dead code
removal, e.g. in opt_hard_wire_dead_code_branches() where we check in
insn_is_cond_jump() for jump opcodes it still only tests for BPF_JMP
class whereas BPF_JMP32 handling needs to be taught here as well.

Thanks,
Daniel