Re: [PATCH dwarves] pahole, btf_encoder: Collect info of per-cpu varaibles from threads.

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Mon, Mar 21, 2022 at 4:08 PM Kui-Feng Lee <kuifeng@fb.com> wrote:
>
> Collect the information of per-cpu variables from encoders of worker
> threads to the primary encoder.
>
> btf_encoder store per-cpu info separately, not in btf.  Previously, it
> merged only btf types generated by worker threads.  So, some of the
> per-cpu info was missing.
>
> Signed-off-by: Kui-Feng Lee <kuifeng@fb.com>
> ---

I've applied this locally and tested, it all looks good, thanks! I'm
keeping this applied locally until Arnaldo pushes this to master :)

Acked-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Andrii Nakryiko <andrii@kernel.org>

>  btf_encoder.c | 21 +++++++++++++++++++++
>  btf_encoder.h |  2 ++
>  pahole.c      |  2 +-
>  3 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/btf_encoder.c b/btf_encoder.c
> index fa29824..1a42094 100644
> --- a/btf_encoder.c
> +++ b/btf_encoder.c
> @@ -606,6 +606,27 @@ static int32_t btf_encoder__add_var_secinfo(struct btf_encoder *encoder, uint32_
>         return gobuffer__add(&encoder->percpu_secinfo, &si, sizeof(si));
>  }
>
> +int32_t btf_encoder__add_encoder(struct btf_encoder *encoder, struct btf_encoder *other)
> +{
> +       struct gobuffer *var_secinfo_buf = &other->percpu_secinfo;
> +       size_t sz = gobuffer__size(var_secinfo_buf);
> +       uint16_t nr_var_secinfo = sz / sizeof(struct btf_var_secinfo);
> +       uint32_t type_id;
> +       uint32_t next_type_id = btf__type_cnt(encoder->btf);
> +       int32_t i, id;
> +       struct btf_var_secinfo *vsi;
> +
> +       for (i = 0; i < nr_var_secinfo; i++) {
> +               vsi = (struct btf_var_secinfo *)var_secinfo_buf->entries + i;
> +               type_id = next_type_id + vsi->type - 1; /* Type ID starts from 1 */
> +               id = btf_encoder__add_var_secinfo(encoder, type_id, vsi->offset, vsi->size);
> +               if (id < 0)
> +                       return id;
> +       }
> +
> +       return btf__add_btf(encoder->btf, other->btf);
> +}
> +
>  static int32_t btf_encoder__add_datasec(struct btf_encoder *encoder, const char *section_name)
>  {
>         struct gobuffer *var_secinfo_buf = &encoder->percpu_secinfo;
> diff --git a/btf_encoder.h b/btf_encoder.h
> index 0f0eee8..339fae2 100644
> --- a/btf_encoder.h
> +++ b/btf_encoder.h
> @@ -31,4 +31,6 @@ struct btf_encoder *btf_encoders__next(struct btf_encoder *encoder);
>
>  struct btf *btf_encoder__btf(struct btf_encoder *encoder);
>
> +int btf_encoder__add_encoder(struct btf_encoder *encoder, struct btf_encoder *other);
> +
>  #endif /* _BTF_ENCODER_H_ */
> diff --git a/pahole.c b/pahole.c
> index f7c7966..a909b22 100644
> --- a/pahole.c
> +++ b/pahole.c
> @@ -2867,7 +2867,7 @@ static int pahole_threads_collect(struct conf_load *conf, int nr_threads, void *
>                  */
>                 if (!threads[i]->btf || threads[i]->encoder == btf_encoder)
>                         continue; /* The primary btf_encoder */
> -               err = btf__add_btf(btf_encoder__btf(btf_encoder), threads[i]->btf);
> +               err = btf_encoder__add_encoder(btf_encoder, threads[i]->encoder);
>                 if (err < 0)
>                         goto out;
>                 btf_encoder__delete(threads[i]->encoder);
> --
> 2.30.2
>