netdev - Re: arch: arm: bpf: Converting cBPF to eBPF for arm 32 bit

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Message-ID: <CAHgaXdJ1M4W3p9=B2hJmtxByPsA5-XHae8U6YtDH_2r_XMaR5A@mail.gmail.com>
Date:   Thu, 6 Apr 2017 16:35:17 +0530
From:   Shubham Bansal <illusionist.neo@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     David Miller <davem@...emloft.net>,
        Kees Cook <keescook@...omium.org>,
        Mircea Gherzan <mgherzan@...il.com>,
        Network Development <netdev@...r.kernel.org>,
        kernel-hardening@...ts.openwall.com,
        linux-arm-kernel@...ts.infradead.org, ast@...com
Subject: Re: arch: arm: bpf: Converting cBPF to eBPF for arm 32 bit

Gentle Reminder.

Anybody can tell me how to test the JIT compiler ?
Best,
Shubham Bansal


On Thu, Mar 30, 2017 at 7:34 PM, Shubham Bansal
<illusionist.neo@...il.com> wrote:
> Thanks Daniel.
>
> Can you tell me how to test the eBPF JIT compiler? It would be great
> if you could tell me starting from compiling to proper testing.
> Best,
> Shubham Bansal
>
>
> On Wed, Mar 29, 2017 at 5:30 AM, Daniel Borkmann <daniel@...earbox.net> wrote:
>> Hi Shubham,
>>
>> On 03/28/2017 10:49 PM, Shubham Bansal wrote:
>> [...]
>>>
>>> Do you have any document to understand the working of tail calls? I
>>> looked at your presentations but it seemed confusing to me. Anything
>>> simple would be great, just about the tail calls. I don't think I need
>>> examples, I can get them from your presentations. I just need a very
>>> general idea. May be you know the code in kernel where it is
>>> implemented.
>>
>>
>> Sure, it's in __bpf_prog_run(), see the JMP_TAIL_CALL (kernel/bpf/core.c
>> +1019).
>> That's effectively what JITs implement. [1] page 3 has a high-level
>> description
>> as well, hope that helps.
>>
>> Thanks,
>> Daniel
>>
>>   [1]
>> http://www.netdevconf.org/1.1/proceedings/papers/On-getting-tc-classifier-fully-programmable-with-cls-bpf.pdf