On Fri, Aug 30, 2024 at 9:00 AM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > 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(+) > > Also added Fixes: ba451366bf44 ("libbpf: Implement basic split BTF support") Fixes: 58e185a0dc35 ("libbpf: Add btf__distill_base() creating split BTF with distilled base BTF") > > 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 > >
