selftests/bpf: add bpf_wq tests

Add bpf_wq selftests to verify:
 * BPF program using non-constant offset of struct bpf_wq is rejected
 * BPF program using map with no BTF for storing struct bpf_wq is
 rejected

Signed-off-by: Mykyta Yatsenko <[email protected]>
Tested-by: Eduard Zingerman <[email protected]>

Author: mykyta5

tools/testing/selftests/bpf/prog_tests/wq.c

@@ -38,3 +38,47 @@ void serial_test_failures_wq(void)
 {
 	RUN_TESTS(wq_failures);
 }
+
+static void test_failure_map_no_btf(void)
+{
+	struct wq *skel = NULL;
+	char log[8192];
+	const struct bpf_insn *insns;
+	size_t insn_cnt;
+	int ret, err, map_fd;
+	LIBBPF_OPTS(bpf_prog_load_opts, opts, .log_size = sizeof(log), .log_buf = log,
+		    .log_level = 2);
+
+	skel = wq__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	err = bpf_object__prepare(skel->obj);
+	if (!ASSERT_OK(err, "skel__prepare"))
+		goto out;
+
+	map_fd = bpf_map_create(BPF_MAP_TYPE_ARRAY, "map_no_btf", sizeof(__u32), sizeof(__u64), 100,
+				NULL);
+	if (!ASSERT_GT(map_fd, -1, "map create"))
+		goto out;
+
+	err = bpf_map__reuse_fd(skel->maps.array, map_fd);
+	if (!ASSERT_OK(err, "map reuse fd"))
+		goto out;
+
+	insns = bpf_program__insns(skel->progs.test_map_no_btf);
+	insn_cnt = bpf_program__insn_cnt(skel->progs.test_map_no_btf);
+	ret = bpf_prog_load(BPF_PROG_TYPE_TRACEPOINT, NULL, "GPL", insns, insn_cnt, &opts);
+
+	ASSERT_NEQ(ret, 0, "prog load failed");
+	ASSERT_HAS_SUBSTR(log, "map 'map_no_btf' has to have BTF in order to use bpf_wq",
+			  "log complains no map BTF");
+out:
+	wq__destroy(skel);
+}
+
+void test_wq_custom(void)
+{
+	if (test__start_subtest("test_failure_map_no_btf"))
+		test_failure_map_no_btf();
+}

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

@@ -187,3 +187,20 @@ long test_call_lru_sleepable(void *ctx)
 
 	return test_elem_callback(&lru, &key, wq_callback);
 }
+
+SEC("tc")
+long test_map_no_btf(void *ctx)
+{
+	struct elem *val;
+	struct bpf_wq *wq;
+	int key = 42;
+
+	val = bpf_map_lookup_elem(&array, &key);
+	if (!val)
+		return -2;
+
+	wq = &val->w;
+	if (bpf_wq_init(wq, &array, 0) != 0)
+		return -3;
+	return 0;
+}

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

@@ -142,3 +142,26 @@ long test_wrong_wq_pointer_offset(void *ctx)
 
 	return -22;
 }
+
+SEC("tc")
+__log_level(2)
+__failure
+__msg(": (85) call bpf_wq_init#")
+__msg("R1 doesn't have constant offset. bpf_wq has to be at the constant offset")
+long test_bad_wq_off(void *ctx)
+{
+	struct elem *val;
+	struct bpf_wq *wq;
+	int key = 42;
+	u64 unknown;
+
+	val = bpf_map_lookup_elem(&array, &key);
+	if (!val)
+		return -2;
+
+	unknown = bpf_get_prandom_u32();
+	wq = &val->w + unknown;
+	if (bpf_wq_init(wq, &array, 0) != 0)
+		return -3;
+	return 0;
+}