netdev - Re: [PATCH] net: filter: make JITs zero A for SKF_AD_ALU_XOR

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Date:	Tue, 05 Jan 2016 17:37:54 +0100
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Rabin Vincent <rabin@....in>, Eric Dumazet <eric.dumazet@...il.com>
CC:	davem@...emloft.net, netdev@...r.kernel.org, ast@...nel.org,
	linux-arm-kernel@...ts.infradead.org, linux-mips@...ux-mips.org,
	linuxppc-dev@...ts.ozlabs.org, sparclinux@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: filter: make JITs zero A for SKF_AD_ALU_XOR_X

On 01/05/2016 05:03 PM, Rabin Vincent wrote:
> On Tue, Jan 05, 2016 at 08:00:45AM -0800, Eric Dumazet wrote:
>> On Tue, 2016-01-05 at 16:23 +0100, Rabin Vincent wrote:
>>> The SKF_AD_ALU_XOR_X ancillary is not like the other ancillary data
>>> instructions since it XORs A with X while all the others replace A with
>>> some loaded value.  All the BPF JITs fail to clear A if this is used as
>>> the first instruction in a filter.
>>
>> Is x86_64 part of this 'All' subset ? ;)
>
> No, because it's an eBPF JIT.

Correct, filter conversion to eBPF clears it already.
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