> On Oct 4, 2021, at 11:47 PM, andrii.nakryiko@xxxxxxxxx wrote:
>
> From: Andrii Nakryiko <andrii@xxxxxxxxxx>
>
> Add a bulk copying api, btf__add_btf(), that speeds up and simplifies
> appending entire contents of one BTF object to another one, taking care
> of copying BTF type data, adjusting resulting BTF type IDs according to
> their new locations in the destination BTF object, as well as copying
> and deduplicating all the referenced strings and updating all the string
> offsets in new BTF types as appropriate.
>
> This API is intended to be used from tools that are generating and
> otherwise manipulating BTFs generically, such as pahole. In pahole's
> case, this API is useful for speeding up parallelized BTF encoding, as
> it allows pahole to offload all the intricacies of BTF type copying to
> libbpf and handle the parallelization aspects of the process.
>
> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Acked-by: Song Liu <songliubraving@xxxxxx>
with on typo below.
> ---
> tools/lib/bpf/btf.c | 114 ++++++++++++++++++++++++++++++++++++++-
> tools/lib/bpf/btf.h | 22 ++++++++
> tools/lib/bpf/libbpf.map | 1 +
> 3 files changed, 135 insertions(+), 2 deletions(-)
[...]
> diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
> index 2cfe31327920..823e7067d34e 100644
> --- a/tools/lib/bpf/btf.h
> +++ b/tools/lib/bpf/btf.h
> @@ -173,6 +173,28 @@ LIBBPF_API int btf__find_str(struct btf *btf, const char *s);
> LIBBPF_API int btf__add_str(struct btf *btf, const char *s);
> LIBBPF_API int btf__add_type(struct btf *btf, const struct btf *src_btf,
> const struct btf_type *src_type);
> +/**
> + * @brief **btf__add_btf()** appends all the BTF types from *src_btf* into *btf*
> + * @param btf BTF object which all the BTF types and strings are added to
> + * @param src_btf BTF object which all BTF types and referenced strings are copied from
> + * @return BTF type ID of the first appended BTF type, or negative error code
> + *
> + * **btf__add_btf()** can be used to simply and efficiently append the entire
> + * contents of one BTF object to another one. All the BTF type data is copied
> + * over, all referenced type IDs are adjusted by adding a necessary ID offset.
> + * Only strings referenced from BTF types are copied over and deduplicated, so
> + * if there were some unused strings in *src_btf*, those won't be copied over,
> + * which is consistent with the general string deduplication semantics of BTF
> + * writing APIs.
> + *
> + * If any error is encountered during this process, the contents of *btf* is
> + * left intact, which means that **btf__add_btf()** follows the transactional
> + * semantics and the operation as a whole is all-or-nothing.
> + *
> + * *src_btf* has to be non-split BTF, as of now copying types from split BTF
> + * is not supported and will result in -OPNOTSUP error code returned.
^^^ typo: -ENOTSUP
>
> + */
> +LIBBPF_API int btf__add_btf(struct btf *btf, const struct btf *src_btf);
>
> LIBBPF_API int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding);
> LIBBPF_API int btf__add_float(struct btf *btf, const char *name, size_t byte_sz);
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index 9e649cf9e771..f6b0db1e8c8b 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -389,5 +389,6 @@ LIBBPF_0.5.0 {
>
> LIBBPF_0.6.0 {
> global:
> + btf__add_btf;
> btf__add_tag;
> } LIBBPF_0.5.0;
> --
> 2.30.2
>
