bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: "Mauricio Vásquez" <mauricio@kinvolk.io>
Cc: Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Quentin Monnet <quentin@isovalent.com>,
	Rafael David Tinoco <rafaeldtinoco@gmail.com>,
	Lorenzo Fontana <lorenzo.fontana@elastic.co>,
	Leonardo Di Donato <leonardo.didonato@elastic.co>
Subject: Re: [PATCH bpf-next v7 5/7] bpftool: Implement btfgen_get_btf()
Date: Wed, 16 Feb 2022 10:20:37 -0800	[thread overview]
Message-ID: <CAEf4BzakR4cbe7aT09y5tnGebrixj8RnZsg13G+VLqpgQoWa7Q@mail.gmail.com> (raw)
In-Reply-To: <20220215225856.671072-6-mauricio@kinvolk.io>

On Tue, Feb 15, 2022 at 2:59 PM Mauricio Vásquez <mauricio@kinvolk.io> wrote:
>
> The last part of the BTFGen algorithm is to create a new BTF object with
> all the types that were recorded in the previous steps.
>
> This function performs two different steps:
> 1. Add the types to the new BTF object by using btf__add_type(). Some
> special logic around struct and unions is implemented to only add the
> members that are really used in the field-based relocations. The type
> ID on the new and old BTF objects is stored on a map.
> 2. Fix all the type IDs on the new BTF object by using the IDs saved in
> the previous step.
>
> Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
> Signed-off-by: Rafael David Tinoco <rafael.tinoco@aquasec.com>
> Signed-off-by: Lorenzo Fontana <lorenzo.fontana@elastic.co>
> Signed-off-by: Leonardo Di Donato <leonardo.didonato@elastic.co>
> ---
>  tools/bpf/bpftool/gen.c | 100 +++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 99 insertions(+), 1 deletion(-)
>

[...]

> +                       cloned_m = btf_members(cloned_type);
> +                       m = btf_members(type);
> +                       vlen = btf_vlen(cloned_type);
> +                       for (idx_src = 0; idx_src < vlen; idx_src++, cloned_m++, m++) {
> +                               /* add only members that are marked as used */
> +                               if (cloned_m->name_off != MARKED)
> +                                       continue;
> +
> +                               name = btf__str_by_offset(info->src_btf, m->name_off);
> +                               err = btf__add_field(btf_new, name, m->type,
> +                                                    BTF_MEMBER_BIT_OFFSET(m->offset),
> +                                                    BTF_MEMBER_BITFIELD_SIZE(m->offset));

BTF_MEMBER_BIT_OFFSET() and BTF_MEMBER_BIT_OFFSET() shouldn't be used
unconditionally, only if kflag is set. It's better to use
btf_member_bit_offset() and btf_member_bitfield_size() helpers here,
they handle this transparently.

> +                               if (err < 0)
> +                                       goto err_out;
> +                       }
> +               } else {
> +                       err = btf__add_type(btf_new, info->src_btf, type);
> +                       if (err < 0)
> +                               goto err_out;
> +                       new_id = err;
> +               }
> +
> +               /* add ID mapping */
> +               ids[i] = new_id;
> +       }
> +

[...]

  reply	other threads:[~2022-02-16 18:20 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-02-15 22:58 [PATCH bpf-next v7 0/7] libbpf: Implement BTFGen Mauricio Vásquez
2022-02-15 22:58 ` [PATCH bpf-next v7 1/7] libbpf: split bpf_core_apply_relo() Mauricio Vásquez
2022-02-16  1:52   ` Alexei Starovoitov
2022-02-15 22:58 ` [PATCH bpf-next v7 2/7] libbpf: Expose bpf_core_{add,free}_cands() to bpftool Mauricio Vásquez
2022-02-15 22:58 ` [PATCH bpf-next v7 3/7] bpftool: Add gen min_core_btf command Mauricio Vásquez
2022-02-15 22:58 ` [PATCH bpf-next v7 4/7] bpftool: Implement "gen min_core_btf" logic Mauricio Vásquez
2022-02-18 16:20   ` Quentin Monnet
2022-02-18 19:43     ` Mauricio Vásquez Bernal
2022-02-18 19:48       ` Andrii Nakryiko
2022-02-18 19:52         ` Quentin Monnet
2022-02-15 22:58 ` [PATCH bpf-next v7 5/7] bpftool: Implement btfgen_get_btf() Mauricio Vásquez
2022-02-16 18:20   ` Andrii Nakryiko [this message]
2022-02-15 22:58 ` [PATCH bpf-next v7 6/7] bpftool: gen min_core_btf explanation and examples Mauricio Vásquez
2022-02-16 18:20   ` Andrii Nakryiko
2022-02-15 22:58 ` [PATCH bpf-next v7 7/7] selftests/bpf: Test "bpftool gen min_core_btf" Mauricio Vásquez
2022-02-16 18:20   ` Andrii Nakryiko
2022-02-16 18:20 ` [PATCH bpf-next v7 0/7] libbpf: Implement BTFGen Andrii Nakryiko
2022-02-17 22:07   ` Mauricio Vásquez Bernal
2022-02-17 22:12     ` Andrii Nakryiko
2022-02-16 18:30 ` patchwork-bot+netdevbpf

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAEf4BzakR4cbe7aT09y5tnGebrixj8RnZsg13G+VLqpgQoWa7Q@mail.gmail.com \
    --to=andrii.nakryiko@gmail.com \
    --cc=andrii@kernel.org \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=leonardo.didonato@elastic.co \
    --cc=lorenzo.fontana@elastic.co \
    --cc=mauricio@kinvolk.io \
    --cc=netdev@vger.kernel.org \
    --cc=quentin@isovalent.com \
    --cc=rafaeldtinoco@gmail.com \
    --subject='Re: [PATCH bpf-next v7 5/7] bpftool: Implement btfgen_get_btf()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).