On Fri, Aug 30, 2024 at 2:52 AM Tony Ambardar <tony.ambardar@xxxxxxxxx> wrote: > > The pahole master branch recently added support for "distilled BTF" based > on libbpf v1.5, but may add .BTF and .BTF.base sections with the wrong byte there is no libbpf v1.5 release, are we talking about using unreleased master branch? > order (e.g. on s390x BPF CI), which then lead to kernel Oops when loaded. > > Fix by updating libbpf's btf__distill_base() and btf_new_empty() to retain > the byte order of any source BTF objects when creating new ones. > > Reported-by: Song Liu <song@xxxxxxxxxx> > Reported-by: Eduard Zingerman <eddyz87@xxxxxxxxx> > Suggested-by: Eduard Zingerman <eddyz87@xxxxxxxxx> > Link: https://lore.kernel.org/bpf/6358db36c5f68b07873a0a5be2d062b1af5ea5f8.camel@xxxxxxxxx/ > Signed-off-by: Tony Ambardar <tony.ambardar@xxxxxxxxx> > --- > tools/lib/bpf/btf.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c > index 064cfe126c09..7726b7c6d40a 100644 > --- a/tools/lib/bpf/btf.c > +++ b/tools/lib/bpf/btf.c > @@ -996,6 +996,7 @@ static struct btf *btf_new_empty(struct btf *base_btf) > btf->base_btf = base_btf; > btf->start_id = btf__type_cnt(base_btf); > btf->start_str_off = base_btf->hdr->str_len; > + btf->swapped_endian = base_btf->swapped_endian; > } > > /* +1 for empty string at offset 0 */ > @@ -5554,6 +5555,10 @@ int btf__distill_base(const struct btf *src_btf, struct btf **new_base_btf, > new_base = btf__new_empty(); > if (!new_base) > return libbpf_err(-ENOMEM); > + err = btf__set_endianness(new_base, btf__endianness(src_btf)); > + if (err < 0) > + goto done; This error check is really unnecessary and paranoid, because the only way btf__set_endianness() can fail is if the provided endianness enum is corrupted (some invalid int cast to enum). But in this case we are getting it from libbpf itself, which will always be correct. So I think I'll drop the error check while applying. > + > dist.id_map = calloc(n, sizeof(*dist.id_map)); > if (!dist.id_map) { > err = -ENOMEM; > -- > 2.34.1 >
