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

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Message-ID: <CAEf4BzZAS71B6AQk2WCLA3d_vtsyYrA5bYT4YF0Wz7H=0XP8Fw@mail.gmail.com>
Date:   Tue, 1 Dec 2020 13:49:40 -0800
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Andrii Nakryiko <andrii@...nel.org>, bpf <bpf@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        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 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?

[...]