netdev - Re: [PATCH v3 bpf-next 0/7] libbpf: add support for kernel module BTF CO-RE relocations

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Message-ID: <728b74ef-70c6-0031-fefa-804e290bdb0b@fb.com>
Date:   Tue, 1 Dec 2020 14:22:25 -0800
From:   Alexei Starovoitov <ast@...com>
To:     Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
CC:     Andrii Nakryiko <andrii@...nel.org>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v3 bpf-next 0/7] libbpf: add support for kernel module BTF
 CO-RE relocations

On 12/1/20 1:49 PM, Andrii Nakryiko wrote:
> On Tue, Dec 1, 2020 at 1:30 PM Alexei Starovoitov
> <alexei.starovoitov@...il.com> wrote:
>>
>> On Mon, Nov 30, 2020 at 7:49 PM Andrii Nakryiko <andrii@...nel.org> wrote:
>>>
>>> Implement libbpf support for performing CO-RE relocations against types in
>>> kernel module BTFs, in addition to existing vmlinux BTF support.
>>>
>>> This is a first step towards fully supporting kernel module BTFs. Subsequent
>>> patch sets will expand kernel and libbpf sides to allow using other
>>> BTF-powered capabilities (fentry/fexit, struct_ops, ksym externs, etc). For
>>> CO-RE relocations support, though, no extra kernel changes are necessary.
>>>
>>> This patch set also sets up a convenient and fully-controlled custom kernel
>>> module (called "bpf_testmod"), that is a predictable playground for all the
>>> BPF selftests, that rely on module BTFs.
>>>
>>> v2->v3:
>>>    - fix subtle uninitialized variable use in BTF ID iteration code;
>>
>> While testing this patch I've hit this:
> 
> Right, I ran into that while testing the second patch set
> (fexit/fentry one), and fixed in patch "bpf: keep module's
> btf_data_size intact after load". But I've mistakenly added it to the
> second patch set, not to this one, my bad. I'll move it into this one.
> Or maybe I should just combine those two now for easier logistics?

whichever way. Combining is fine by me, since I've looked at both sets 
already.