selftests/bpf: Add two selftests for mprog API based cgroup progs

Two tests are added:
  - cgroup_mprog_opts, which mimics tc_opts.c ([1]). Both prog and link
    attach are tested. Some negative tests are also included.
  - cgroup_mprog_ordering, which actually runs the program with some mprog
    API flags.

  [1] https://github.com/torvalds/linux/blob/master/tools/testing/selftests/bpf/prog_tests/tc_opts.c

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250606163156.2429955-1-yonghong.song@linux.dev

1 files changed, 30 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/progs/cgroup_mprog.c b/tools/testing/selftests/bpf/progs/cgroup_mprog.c
new file mode 100644
index 000000000000..6a0ea02c4de2
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/cgroup_mprog.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+char _license[] SEC("license") = "GPL";
+
+SEC("cgroup/getsockopt")
+int getsockopt_1(struct bpf_sockopt *ctx)
+{
+	return 1;
+}
+
+SEC("cgroup/getsockopt")
+int getsockopt_2(struct bpf_sockopt *ctx)
+{
+	return 1;
+}
+
+SEC("cgroup/getsockopt")
+int getsockopt_3(struct bpf_sockopt *ctx)
+{
+	return 1;
+}
+
+SEC("cgroup/getsockopt")
+int getsockopt_4(struct bpf_sockopt *ctx)
+{
+	return 1;
+}