1 files changed, 47 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/test_skb_cgroup_id_kern.c b/tools/testing/selftests/bpf/progs/test_skb_cgroup_id_kern.c
new file mode 100644
index 000000000000..68cf9829f5a7
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_skb_cgroup_id_kern.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Facebook
+
+#include <linux/bpf.h>
+#include <linux/pkt_cls.h>
+
+#include <string.h>
+
+#include "bpf_helpers.h"
+
+#define NUM_CGROUP_LEVELS	4
+
+struct bpf_map_def SEC("maps") cgroup_ids = {
+	.type = BPF_MAP_TYPE_ARRAY,
+	.key_size = sizeof(__u32),
+	.value_size = sizeof(__u64),
+	.max_entries = NUM_CGROUP_LEVELS,
+};
+
+static __always_inline void log_nth_level(struct __sk_buff *skb, __u32 level)
+{
+	__u64 id;
+
+	/* [1] &level passed to external function that may change it, it's
+	 *     incompatible with loop unroll.
+	 */
+	id = bpf_skb_ancestor_cgroup_id(skb, level);
+	bpf_map_update_elem(&cgroup_ids, &level, &id, 0);
+}
+
+SEC("cgroup_id_logger")
+int log_cgroup_id(struct __sk_buff *skb)
+{
+	/* Loop unroll can't be used here due to [1]. Unrolling manually.
+	 * Number of calls should be in sync with NUM_CGROUP_LEVELS.
+	 */
+	log_nth_level(skb, 0);
+	log_nth_level(skb, 1);
+	log_nth_level(skb, 2);
+	log_nth_level(skb, 3);
+
+	return TC_ACT_OK;
+}
+
+int _version SEC("version") = 1;
+
+char _license[] SEC("license") = "GPL";