Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2021-04-01

The following pull-request contains BPF updates for your *net-next* tree.

We've added 68 non-merge commits during the last 7 day(s) which contain
a total of 70 files changed, 2944 insertions(+), 1139 deletions(-).

The main changes are:

1) UDP support for sockmap, from Cong.

2) Verifier merge conflict resolution fix, from Daniel.

3) xsk selftests enhancements, from Maciej.

4) Unstable helpers aka kernel func calling, from Martin.

5) Batches ops for LPM map, from Pedro.

6) Fix race in bpf_get_local_storage, from Yonghong.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 28 insertions, 9 deletions

diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 5e0aa2f2c0ca..46b16cbdcda3 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -94,6 +94,7 @@ struct dst_sec {
 	int sec_sym_idx;
 
 	/* section's DATASEC variable info, emitted on BTF finalization */
+	bool has_btf;
 	int sec_var_cnt;
 	struct btf_var_secinfo *sec_vars;
 
@@ -1436,6 +1437,16 @@ static int linker_append_btf(struct bpf_linker *linker, struct src_obj *obj)
 			continue;
 		dst_sec = &linker->secs[src_sec->dst_id];
 
+		/* Mark section as having BTF regardless of the presence of
+		 * variables. In some cases compiler might generate empty BTF
+		 * with no variables information. E.g., when promoting local
+		 * array/structure variable initial values and BPF object
+		 * file otherwise has no read-only static variables in
+		 * .rodata. We need to preserve such empty BTF and just set
+		 * correct section size.
+		 */
+		dst_sec->has_btf = true;
+
 		t = btf__type_by_id(obj->btf, src_sec->sec_type_id);
 		src_var = btf_var_secinfos(t);
 		n = btf_vlen(t);
@@ -1717,7 +1728,7 @@ static int finalize_btf(struct bpf_linker *linker)
 	for (i = 1; i < linker->sec_cnt; i++) {
 		struct dst_sec *sec = &linker->secs[i];
 
-		if (!sec->sec_var_cnt)
+		if (!sec->has_btf)
 			continue;
 
 		id = btf__add_datasec(btf, sec->sec_name, sec->sec_sz);
@@ -1895,8 +1906,10 @@ static int finalize_btf_ext(struct bpf_linker *linker)
 			struct dst_sec *sec = &linker->secs[i];
 
 			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->func_info);
-			if (sz < 0)
-				return sz;
+			if (sz < 0) {
+				err = sz;
+				goto out;
+			}
 
 			cur += sz;
 		}
@@ -1910,8 +1923,10 @@ static int finalize_btf_ext(struct bpf_linker *linker)
 			struct dst_sec *sec = &linker->secs[i];
 
 			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->line_info);
-			if (sz < 0)
-				return sz;
+			if (sz < 0) {
+				err = sz;
+				goto out;
+			}
 
 			cur += sz;
 		}
@@ -1925,8 +1940,10 @@ static int finalize_btf_ext(struct bpf_linker *linker)
 			struct dst_sec *sec = &linker->secs[i];
 
 			sz = emit_btf_ext_data(linker, cur, sec->sec_name, &sec->core_relo_info);
-			if (sz < 0)
-				return sz;
+			if (sz < 0) {
+				err = sz;
+				goto out;
+			}
 
 			cur += sz;
 		}
@@ -1937,8 +1954,10 @@ static int finalize_btf_ext(struct bpf_linker *linker)
 	if (err) {
 		linker->btf_ext = NULL;
 		pr_warn("failed to parse final .BTF.ext data: %d\n", err);
-		return err;
+		goto out;
 	}
 
-	return 0;
+out:
+	free(data);
+	return err;
 }