On Wed, Apr 24, 2024 at 8:49 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> When resolving BTF ids, use the BTF in the module .BTF.base section
> when passed the -B option. Both references to base BTF from split
> BTF and BTF ids will be relocated for base vmlinux on module load.
>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> ---
> tools/bpf/resolve_btfids/main.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
> index d9520cb826b3..c5b622a31f18 100644
> --- a/tools/bpf/resolve_btfids/main.c
> +++ b/tools/bpf/resolve_btfids/main.c
> @@ -115,6 +115,7 @@ struct object {
> const char *path;
> const char *btf;
> const char *base_btf_path;
> + int base;
>
> struct {
> int fd;
> @@ -532,11 +533,26 @@ static int symbols_resolve(struct object *obj)
> __u32 nr_types;
>
> if (obj->base_btf_path) {
> - base_btf = btf__parse(obj->base_btf_path, NULL);
> + LIBBPF_OPTS(btf_parse_opts, optp);
> + const char *path;
> +
> + if (obj->base) {
> + optp.btf_sec = BTF_BASE_ELF_SEC;
> + path = obj->path;
> + base_btf = btf__parse_opts(path, &optp);
> + /* fall back to normal base parsing if no BTF_BASE_ELF_SEC */
> + if (libbpf_get_error(base_btf))
don't add new uses of libbpf_get_error(), it will be eventually
removed, as it's now quire error prone. Just check pointer and then
access errno, if necessary
> + base_btf = NULL;
> + }
> + if (!base_btf) {
> + optp.btf_sec = BTF_ELF_SEC;
> + path = obj->base_btf_path;
> + base_btf = btf__parse_opts(path, &optp);
> + }
> err = libbpf_get_error(base_btf);
> if (err) {
> pr_err("FAILED: load base BTF from %s: %s\n",
> - obj->base_btf_path, strerror(-err));
> + path, strerror(-err));
> return -1;
> }
> }
> @@ -781,6 +797,8 @@ int main(int argc, const char **argv)
> "BTF data"),
> OPT_STRING('b', "btf_base", &obj.base_btf_path, "file",
> "path of file providing base BTF"),
> + OPT_INCR('B', "base", &obj.base,
> + "use " BTF_BASE_ELF_SEC " ELF section BTF as base"),
> OPT_END()
> };
> int err = -1;
> --
> 2.31.1
>
