netdev - Re: [PATCH rfc bpf-next 5/8] bpf: add jit poke descriptor mock-up for jit images

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Message-ID: <10321d85-b9e5-e786-53eb-b4ff6d981e2c@iogearbox.net>
Date:   Mon, 18 Nov 2019 19:43:36 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        john fastabend <john.fastabend@...il.com>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>
Subject: Re: [PATCH rfc bpf-next 5/8] bpf: add jit poke descriptor mock-up for
 jit images

On 11/18/19 7:17 PM, Andrii Nakryiko wrote:
> On Thu, Nov 14, 2019 at 5:05 PM Daniel Borkmann <daniel@...earbox.net> wrote:
>>
>> Add initial poke table data structures and management to the BPF
>> prog that can later be used by JITs. Also add an instance of poke
>> specific data for tail call maps. Plan for later work is to extend
>> this also for BPF static keys.
>>
>> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
>> ---
> 
> looks good, just one more minor naming nit
> 
> Acked-by: Andrii Nakryiko <andriin@...com>
> 
>>   include/linux/bpf.h    | 20 ++++++++++++++++++++
>>   include/linux/filter.h | 10 ++++++++++
>>   kernel/bpf/core.c      | 34 ++++++++++++++++++++++++++++++++++
>>   3 files changed, 64 insertions(+)
>>
>> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
>> index 40337fa0e463..0ff06a0d0058 100644
>> --- a/include/linux/bpf.h
>> +++ b/include/linux/bpf.h
>> @@ -484,6 +484,24 @@ struct bpf_func_info_aux {
>>          bool unreliable;
>>   };
>>
>> +enum bpf_jit_poke_reason {
>> +       BPF_POKE_REASON_TAIL_CALL,
>> +};
>> +
>> +/* Descriptor of pokes pointing /into/ the JITed image. */
>> +struct bpf_jit_poke_descriptor {
>> +       void *ip;
>> +       union {
>> +               struct {
>> +                       struct bpf_map *map;
>> +                       u32 key;
>> +               } tc;
> 
> tc is a bit overloaded abbreviation, tail_call would be super-clear, though ;)

Ok, sure, will include it into the non-rfc version.

>> +       };
>> +       u8 ip_stable;
>> +       u8 adj_off;
>> +       u16 reason;
>> +};
>> +
> 
> [...]
>