From: Song Liu <song@kernel.org>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: bpf <bpf@vger.kernel.org>, "Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Martin KaFai Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>, "Yonghong Song" <yhs@fb.com>,
"Jesper Dangaard Brouer" <brouer@redhat.com>,
"Toke Høiland-Jørgensen" <toke@redhat.com>,
Networking <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next v1 2/6] libbpf: Add typeless and weak ksym support to gen_loader
Date: Thu, 7 Oct 2021 14:45:10 -0700 [thread overview]
Message-ID: <CAPhsuW6nCQK71aeyR1YthvMWGNgH--RwbLnA0_rhi071juTsYg@mail.gmail.com> (raw)
In-Reply-To: <20211006002853.308945-3-memxor@gmail.com>
On Tue, Oct 5, 2021 at 5:29 PM Kumar Kartikeya Dwivedi <memxor@gmail.com> wrote:
>
> This patch adds typeless and weak ksym support to BTF_KIND_VAR
> relocation code in gen_loader. For typeless ksym, we use the newly added
> bpf_kallsyms_lookup_name helper.
>
> For weak ksym, we simply skip error check, and fix up the srg_reg for
> the insn, as keeping it as BPF_PSEUDO_BTF_ID for weak ksym with its
> insn[0].imm and insn[1].imm set as 0 will cause a failure. This is
> consistent with how libbpf relocates these two cases of BTF_KIND_VAR.
>
> We also modify cleanup_relos to check for typeless ksyms in fd closing
> loop, since those have no fd associated with the ksym. For this we can
> reuse the unused 'off' member of ksym_desc.
>
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
[...]
Everything above (trimmed) makes sense to me.
> +/* Expects:
> + * BPF_REG_8 - pointer to instruction
> + */
> +static void emit_relo_ksym_btf(struct bpf_gen *gen, struct ksym_relo_desc *relo, int insn)
> +{
But I don't quite follow why we need these changes to emit_relo_ksym_btf.
Maybe we should have these changes in a separate patch and add some
more explanations?
Thanks,
Song
[...]
next prev parent reply other threads:[~2021-10-07 21:45 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-06 0:28 [PATCH bpf-next v1 0/6] Typeless/weak ksym for gen_loader + misc fixups Kumar Kartikeya Dwivedi
2021-10-06 0:28 ` [PATCH bpf-next v1 1/6] bpf: Add bpf_kallsyms_lookup_name helper Kumar Kartikeya Dwivedi
2021-10-07 20:23 ` Song Liu
2021-10-06 0:28 ` [PATCH bpf-next v1 2/6] libbpf: Add typeless and weak ksym support to gen_loader Kumar Kartikeya Dwivedi
2021-10-07 21:45 ` Song Liu [this message]
2021-10-07 22:01 ` Kumar Kartikeya Dwivedi
2021-10-07 22:17 ` Song Liu
2021-10-06 0:28 ` [PATCH bpf-next v1 3/6] libbpf: Ensure that module BTF fd is never 0 Kumar Kartikeya Dwivedi
2021-10-06 4:41 ` Andrii Nakryiko
2021-10-06 5:24 ` Kumar Kartikeya Dwivedi
2021-10-06 16:43 ` Andrii Nakryiko
2021-10-06 19:09 ` Alexei Starovoitov
2021-10-06 19:38 ` Andrii Nakryiko
2021-10-07 10:24 ` Toke Høiland-Jørgensen
2021-10-07 18:44 ` Kumar Kartikeya Dwivedi
2021-10-07 21:29 ` Andrii Nakryiko
2021-10-06 0:28 ` [PATCH bpf-next v1 4/6] bpf: selftests: Move test_ksyms_weak test to lskel, add libbpf test Kumar Kartikeya Dwivedi
2021-10-07 20:33 ` Song Liu
2021-10-07 20:46 ` Kumar Kartikeya Dwivedi
2021-10-07 20:55 ` Kumar Kartikeya Dwivedi
2021-10-07 20:57 ` Song Liu
2021-10-06 0:28 ` [PATCH bpf-next v1 5/6] bpf: selftests: Fix fd cleanup in sk_lookup test Kumar Kartikeya Dwivedi
2021-10-06 6:49 ` Jakub Sitnicki
2021-10-07 21:48 ` Song Liu
2021-10-06 0:28 ` [PATCH bpf-next v1 6/6] bpf: selftests: Fix memory leak in test_ima Kumar Kartikeya Dwivedi
2021-10-06 4:44 ` Andrii Nakryiko
2021-10-07 21:48 ` Song Liu
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