selftests/bpf: Add mprog API tests for BPF tcx opts

Add a big batch of test coverage to assert all aspects of the tcx opts
attach, detach and query API:

  # ./vmtest.sh -- ./test_progs -t tc_opts
  [...]
  #238     tc_opts_after:OK
  #239     tc_opts_append:OK
  #240     tc_opts_basic:OK
  #241     tc_opts_before:OK
  #242     tc_opts_chain_classic:OK
  #243     tc_opts_demixed:OK
  #244     tc_opts_detach:OK
  #245     tc_opts_detach_after:OK
  #246     tc_opts_detach_before:OK
  #247     tc_opts_dev_cleanup:OK
  #248     tc_opts_invalid:OK
  #249     tc_opts_mixed:OK
  #250     tc_opts_prepend:OK
  #251     tc_opts_replace:OK
  #252     tc_opts_revision:OK
  Summary: 15/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20230719140858.13224-8-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/prog_tests/tc_helpers.h

@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2023 Isovalent */
+#ifndef TC_HELPERS
+#define TC_HELPERS
+#include <test_progs.h>
+
+static inline __u32 id_from_prog_fd(int fd)
+{
+	struct bpf_prog_info prog_info = {};
+	__u32 prog_info_len = sizeof(prog_info);
+	int err;
+
+	err = bpf_obj_get_info_by_fd(fd, &prog_info, &prog_info_len);
+	if (!ASSERT_OK(err, "id_from_prog_fd"))
+		return 0;
+
+	ASSERT_NEQ(prog_info.id, 0, "prog_info.id");
+	return prog_info.id;
+}
+
+static inline __u32 id_from_link_fd(int fd)
+{
+	struct bpf_link_info link_info = {};
+	__u32 link_info_len = sizeof(link_info);
+	int err;
+
+	err = bpf_link_get_info_by_fd(fd, &link_info, &link_info_len);
+	if (!ASSERT_OK(err, "id_from_link_fd"))
+		return 0;
+
+	ASSERT_NEQ(link_info.id, 0, "link_info.id");
+	return link_info.id;
+}
+
+static inline __u32 ifindex_from_link_fd(int fd)
+{
+	struct bpf_link_info link_info = {};
+	__u32 link_info_len = sizeof(link_info);
+	int err;
+
+	err = bpf_link_get_info_by_fd(fd, &link_info, &link_info_len);
+	if (!ASSERT_OK(err, "id_from_link_fd"))
+		return 0;
+
+	return link_info.tcx.ifindex;
+}
+
+static inline void __assert_mprog_count(int target, int expected, bool miniq, int ifindex)
+{
+	__u32 count = 0, attach_flags = 0;
+	int err;
+
+	err = bpf_prog_query(ifindex, target, 0, &attach_flags,
+			     NULL, &count);
+	ASSERT_EQ(count, expected, "count");
+	if (!expected && !miniq)
+		ASSERT_EQ(err, -ENOENT, "prog_query");
+	else
+		ASSERT_EQ(err, 0, "prog_query");
+}
+
+static inline void assert_mprog_count(int target, int expected)
+{
+	__assert_mprog_count(target, expected, false, loopback);
+}
+
+static inline void assert_mprog_count_ifindex(int ifindex, int target, int expected)
+{
+	__assert_mprog_count(target, expected, false, ifindex);
+}
+
+#endif /* TC_HELPERS */

tools/testing/selftests/bpf/progs/test_tc_link.c

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Isovalent */
+#include <stdbool.h>
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+char LICENSE[] SEC("license") = "GPL";
+
+bool seen_tc1;
+bool seen_tc2;
+bool seen_tc3;
+bool seen_tc4;
+
+SEC("tc/ingress")
+int tc1(struct __sk_buff *skb)
+{
+	seen_tc1 = true;
+	return TCX_NEXT;
+}
+
+SEC("tc/egress")
+int tc2(struct __sk_buff *skb)
+{
+	seen_tc2 = true;
+	return TCX_NEXT;
+}
+
+SEC("tc/egress")
+int tc3(struct __sk_buff *skb)
+{
+	seen_tc3 = true;
+	return TCX_NEXT;
+}
+
+SEC("tc/egress")
+int tc4(struct __sk_buff *skb)
+{
+	seen_tc4 = true;
+	return TCX_NEXT;
+}