netdev - Re: [PATCH bpf-next v3 2/8] libbpf: Add typeless ksym support to gen

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Date:   Fri, 15 Oct 2021 06:51:00 +0000
From:   Song Liu <songliubraving@...com>
To:     Kumar Kartikeya Dwivedi <memxor@...il.com>
CC:     "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>, Martin Lau <kafai@...com>,
        Yonghong Song <yhs@...com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next v3 2/8] libbpf: Add typeless ksym support to
 gen_loader



> On Oct 14, 2021, at 1:56 PM, Kumar Kartikeya Dwivedi <memxor@...il.com> wrote:
> 
> This uses the bpf_kallsyms_lookup_name helper added in previous patches
> to relocate typeless ksyms. The return value ENOENT can be ignored, and
> the value written to 'res' can be directly stored to the insn, as it is
> overwritten to 0 on lookup failure. For repeating symbols, we can simply
> copy the previously populated bpf_insn.
> 
> Also, we need to take care to not close fds for typeless ksym_desc, so
> reuse the 'off' member's space to add a marker for typeless ksym and use
> that to skip them in cleanup_relos.
> 
> We add a emit_ksym_relo_log helper that avoids duplicating common
> logging instructions between typeless and weak ksym (for future commit).
> 
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@...il.com>

LGTM! 

Acked-by: Song Liu <songliubraving@...com>