libbpf: Ignore STT_SECTION symbols in 'maps' section

When parsing legacy map definitions, libbpf would error out when
encountering an STT_SECTION symbol. This becomes a problem because some
versions of binutils will produce SECTION symbols for every section when
processing an ELF file, so BPF files run through 'strip' will end up with
such symbols, making libbpf refuse to load them.

There's not really any reason why erroring out is strictly necessary, so
change libbpf to just ignore SECTION symbols when parsing the ELF.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210927205810.715656-1-toke@redhat.com

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ef5db34bf91394e9f763db1269d5ce3d1b71e7c7..453148fe8b4b9e208fd067875c77dbca38a9c1b0 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1869,6 +1869,8 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
                        continue;
                if (sym.st_shndx != obj->efile.maps_shndx)
                        continue;
+               if (GELF_ST_TYPE(sym.st_info) == STT_SECTION)
+                       continue;
 
                map = bpf_object__add_map(obj);
                if (IS_ERR(map))
@@ -1881,8 +1883,7 @@ static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
                        return -LIBBPF_ERRNO__FORMAT;
                }
 
-               if (GELF_ST_TYPE(sym.st_info) == STT_SECTION
-                   || GELF_ST_BIND(sym.st_info) == STB_LOCAL) {
+               if (GELF_ST_BIND(sym.st_info) == STB_LOCAL) {
                        pr_warn("map '%s' (legacy): static maps are not supported\n", map_name);
                        return -ENOTSUP;
                }