From: Johannes Berg <johannes@sipsolutions.net>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>
Subject: Re: eBPF - little-endian load instructions?
Date: Tue, 11 Apr 2017 13:15:30 +0200 [thread overview]
Message-ID: <1491909330.31620.21.camel@sipsolutions.net> (raw)
In-Reply-To: <58ECB8CF.8040409@iogearbox.net>
> Are you working with an skb at that point in time in wifi?
Yes.
> There are
> 3 different ways of accessing skb data, see [1] slide 7 - 10. The BPF
> LD_ABS/IND instructions were carried over from cBPF and are the only
> ones that convert to host endianess. It can be used in eBPF as well,
> but there are more efficient ways like 'direct packet access' or
> helpers such as bpf_skb_load_bytes() that load the raw buffers as-is,
> which is probably what you want if I understand you correctly.
Sounds like, yeah.
> There are instructions to convert endianess, see __bpf_prog_run(),
> the ALU_END_TO_BE, ALU_END_TO_LE labels for details. There's a
> BPF_ENDIAN() macro used in the test suite and other places.
Ok, thanks! :)
So sounds like I don't need anything special - should have a patch to
hook up the wifi stuff soon.
johannes
next prev parent reply other threads:[~2017-04-11 11:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-11 10:38 eBPF - little-endian load instructions? Johannes Berg
2017-04-11 11:06 ` Daniel Borkmann
2017-04-11 11:15 ` Johannes Berg [this message]
2017-04-11 11:22 ` Daniel Borkmann
2017-04-11 11:26 ` Johannes Berg
2017-04-12 13:02 ` Johannes Berg
2017-04-12 16:58 ` Alexei Starovoitov
2017-04-12 19:38 ` Johannes Berg
2017-04-13 3:08 ` Alexei Starovoitov
2017-04-13 5:58 ` Johannes Berg
2017-04-14 18:42 ` Alexei Starovoitov
2017-04-15 7:06 ` Johannes Berg
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