netdev - Re: [PATCH 5/5] bpf: Allow to resolve bpf trampoline in unwind

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Date:   Mon, 03 Feb 2020 21:45:17 +0100
From:   Toke Høiland-Jørgensen <toke@...hat.com>
To:     Björn Töpel <bjorn.topel@...el.com>,
        Jiri Olsa <jolsa@...hat.com>
Cc:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Andrii Nakryiko <andriin@...com>,
        Yonghong Song <yhs@...com>, Martin KaFai Lau <kafai@...com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        David Miller <davem@...hat.com>
Subject: Re: [PATCH 5/5] bpf: Allow to resolve bpf trampoline in unwind

Björn Töpel <bjorn.topel@...el.com> writes:

> On 2020-02-03 20:58, Jiri Olsa wrote:
> [...]
>>>> ...and FWIW, it would be nice with bpf_dispatcher_<...> entries in kallsyms
>>>
>>> ok so it'd be 'bpf_dispatcher_<name>'
>> 
>> hi,
>> so the only dispatcher is currently defined as:
>>    DEFINE_BPF_DISPATCHER(bpf_dispatcher_xdp)
>> 
>> with the bpf_dispatcher_<name> logic it shows in kallsyms as:
>>    ffffffffa0450000 t bpf_dispatcher_bpf_dispatcher_xdp    [bpf]
>>
>
> Ick! :-P
>
>
>> to fix that, would you guys preffer having:
>>    DEFINE_BPF_DISPATCHER(xdp)
>> 
>> or using the full dispatcher name as kallsyms name?
>> which would require some discipline for future dispatcher names ;-)
>>
>
> I'd prefer the latter, i.e. name "xdp" is shown as bpf_dispatcher_xdp in 
> kallsyms.
>
> ...and if this route is taken, the macros can be changed, so that the 
> trampoline functions are prefixed with "bpf_dispatcher_". Something like 
> this (and also a small '_' cleanup):

+1; and thanks for fixing that _ as well - that was really bothering me :)

-Toke