netdev - Re: [PATCH net-next] x86: bpf_jit: small optimization in emit_bpf_tail

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 31 Aug 2017 07:38:20 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Eric Dumazet <eric.dumazet@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        netdev <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH net-next] x86: bpf_jit: small optimization in
 emit_bpf_tail_call()

On Thu, Aug 31, 2017 at 04:53:42AM -0700, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
> 
> Saves 4 bytes replacing following instructions :
> 
> lea rax, [rsi + rdx * 8 + offsetof(...)] 
> mov rax, qword ptr [rax]
> cmp rax, 0
> 
> by :
> 
> mov rax, [rsi + rdx * 8 + offsetof(...)] 
> test rax, rax
> 
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Nicely spotted. Much appreciate it!
Acked-by: Alexei Starovoitov <ast@...nel.org>