selftest/bpf: Add a recursion test

Add recursive non-sleepable fentry program as a test.
All attach points where sleepable progs can execute are non recursive so far.
The recursion protection mechanism for sleepable cannot be activated yet.

Signed-off-by: Alexei Starovoitov <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Acked-by: Andrii Nakryiko <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

1 files changed, 33 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/recursion.c b/tools/testing/selftests/bpf/prog_tests/recursion.c
new file mode 100644
index 000000000000..863757461e3f
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/recursion.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Facebook */
+#include <test_progs.h>
+#include "recursion.skel.h"
+
+void test_recursion(void)
+{
+	struct recursion *skel;
+	int key = 0;
+	int err;
+
+	skel = recursion__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel_open_and_load"))
+		return;
+
+	err = recursion__attach(skel);
+	if (!ASSERT_OK(err, "skel_attach"))
+		goto out;
+
+	ASSERT_EQ(skel->bss->pass1, 0, "pass1 == 0");
+	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash1), &key, 0);
+	ASSERT_EQ(skel->bss->pass1, 1, "pass1 == 1");
+	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash1), &key, 0);
+	ASSERT_EQ(skel->bss->pass1, 2, "pass1 == 2");
+
+	ASSERT_EQ(skel->bss->pass2, 0, "pass2 == 0");
+	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash2), &key, 0);
+	ASSERT_EQ(skel->bss->pass2, 1, "pass2 == 1");
+	bpf_map_lookup_elem(bpf_map__fd(skel->maps.hash2), &key, 0);
+	ASSERT_EQ(skel->bss->pass2, 2, "pass2 == 2");
+out:
+	recursion__destroy(skel);
+}