Re: [PATCH RFCv2] arm64: eBPF JIT compiler

From: Alexei Starovoitov
Date: Thu Jul 10 2014 - 05:51:15 EST


On Wed, Jul 9, 2014 at 3:00 PM, Will Deacon <will.deacon@xxxxxxx> wrote:
> On Tue, Jul 08, 2014 at 08:06:53AM +0100, Zi Shen Lim wrote:
>>
>> 1. Implement remaining classes of eBPF instructions: ST|MEM, STX|XADD
>> which currently do not have corresponding test cases in test_bpf.
>
> I can help out with atomics, if you need it. Are the memory barrier
> semantics well-defined for eBPF?

There are no barrier or cmpxchg instructions in eBPF, since such use case
doesn't exist yet. There is only xadd that is equivalent to atomic_add
which can be JITed as exclusive load/store on arm64.
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