Re: [PATCH bpf-next 0/3] Fix handling of CO-RE relos for __weak subprogs

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next 0/3] Fix handling of CO-RE relos for __weak subprogs
Date: Fri, 8 Apr 2022 11:40:34 -0700	[thread overview]
Message-ID: <CAEf4BzYLYEVic8gfbL1PvhJgpKeVEs0-VM=tgU2kq7ufZPx=CQ@mail.gmail.com> (raw)
In-Reply-To: <20220408181425.2287230-1-andrii@kernel.org>

On Fri, Apr 8, 2022 at 11:14 AM Andrii Nakryiko <andrii@kernel.org> wrote:
>
> Fix the issue accidentally discovered during libbpf USDT support testing.
> Libbpf overzealously complained about CO-RE relocations belonging to the code
> of a __weak subprog that got overriden by another instance of that function.
>
> Fix the issue fixed, return back to __weak __hidden annotation for USDT

"With the issue fixed", sigh...

> BPF-side APIs.
>
> And add CO-RE relos to linked_funcs selftest to ensure such combo keeps
> working going forward.
>
> Andrii Nakryiko (3):
>   libbpf: don't error out on CO-RE relos for overriden weak subprogs
>   libbpf: use weak hidden modifier for USDT BPF-side API functions
>   selftests/bpf: add CO-RE relos into linked_funcs selftests
>
>  tools/lib/bpf/libbpf.c                            | 15 +++++++++++----
>  tools/lib/bpf/usdt.bpf.h                          |  6 +++---
>  tools/testing/selftests/bpf/progs/linked_funcs1.c |  8 ++++++++
>  tools/testing/selftests/bpf/progs/linked_funcs2.c |  8 ++++++++
>  4 files changed, 30 insertions(+), 7 deletions(-)
>
> --
> 2.30.2
>