On Fri, Mar 19, 2021 at 07:58:13PM +0100, Jiri Olsa wrote:

On Fri, Mar 19, 2021 at 11:39:01AM -0700, Andrii Nakryiko wrote:

quoted

On Fri, Mar 19, 2021 at 9:23 AM Jiri Olsa [off-list ref] wrote:

quoted

On Thu, Mar 18, 2021 at 12:40:31PM -0700, Andrii Nakryiko wrote:

SNIP

quoted

+
+     return NULL;
+}
+
+static int linker_fixup_btf(struct src_obj *obj)
+{
+     const char *sec_name;
+     struct src_sec *sec;
+     int i, j, n, m;
+
+     n = btf__get_nr_types(obj->btf);

hi,
I'm getting bpftool crash when building tests,

looks like above obj->btf can be NULL:

I lost if (!obj->btf) return 0; somewhere along the rebases. I'll send
a fix shortly. But how did you end up with selftests BPF objects built
without BTF?

no idea.. I haven't even updated llvm for almost 3 days now ;-)

sorry for late follow up on this, and it's actually forgotten empty
object in progs directory that was causing this

I wonder we should add empty object like below to catch these cases,
because there's another place that bpftool is crashing on with it

I can send full patch for that if you think it's worth having

jirka


---

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 7aad78dbb4b4..aecb6ca52bce 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c

@@ -3165,6 +3165,9 @@ static int add_dummy_ksym_var(struct btf *btf)
 	const struct btf_var_secinfo *vs;
 	const struct btf_type *sec;
 
+	if (!btf)
+		return 0;
+
 	sec_btf_id = btf__find_by_name_kind(btf, KSYMS_SEC,
 					    BTF_KIND_DATASEC);
 	if (sec_btf_id < 0)

diff --git a/tools/testing/selftests/bpf/progs/empty.c b/tools/testing/selftests/bpf/progs/empty.c
new file mode 100644
index 000000000000..e69de29bb2d1