[PATCH bpf-next v4 10/10] selftests/bpf: Add tests for bpf_prog_call()

[Yonghong Song <yonghong.song@linux.dev>]

Add two subtests for nested bpf_prog_call(). One is recursion in main prog,
and the other is recursion in callback func.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 .../selftests/bpf/prog_tests/prog_call.c      | 78 ++++++++++++++++
 tools/testing/selftests/bpf/progs/prog_call.c | 92 +++++++++++++++++++
 2 files changed, 170 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/prog_call.c
 create mode 100644 tools/testing/selftests/bpf/progs/prog_call.c

diff --git a/tools/testing/selftests/bpf/prog_tests/prog_call.c b/tools/testing/selftests/bpf/prog_tests/prog_call.c
new file mode 100644
index 000000000000..573c67c9af12
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/prog_call.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+#include <network_helpers.h>
+#include "prog_call.skel.h"
+
+static void test_nest_prog_call(int prog_index)
+{
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+		.data_in = &pkt_v4,
+		.data_size_in = sizeof(pkt_v4),
+	);
+	int err, idx = 0, prog_fd, map_fd;
+	struct prog_call *skel;
+	struct bpf_program *prog;
+
+	skel = prog_call__open();
+	if (!ASSERT_OK_PTR(skel, "prog_call__open"))
+		return;
+
+	switch (prog_index) {
+	case 0:
+		prog = skel->progs.entry_no_subprog;
+		break;
+	case 1:
+		prog = skel->progs.entry_subprog;
+		break;
+	case 2:
+		prog = skel->progs.entry_callback;
+		break;
+	}
+
+	bpf_program__set_autoload(prog, true);
+
+	err = prog_call__load(skel);
+	if (!ASSERT_OK(err, "prog_call__load"))
+		return;
+
+	map_fd = bpf_map__fd(skel->maps.jmp_table);
+	prog_fd = bpf_program__fd(prog);
+	/* maximum recursion level 4 */
+	err = bpf_map_update_elem(map_fd, &idx, &prog_fd, 0);
+	if (!ASSERT_OK(err, "bpf_map_update_elem"))
+		goto out;
+
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(skel->bss->vali, 4, "i");
+	ASSERT_EQ(skel->bss->valj, 6, "j");
+out:
+	prog_call__destroy(skel);
+}
+
+static void test_prog_call_with_tailcall(void)
+{
+	struct prog_call *skel;
+	int err;
+
+	skel = prog_call__open();
+	if (!ASSERT_OK_PTR(skel, "prog_call__open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.entry_tail_call, true);
+	err = prog_call__load(skel);
+	if (!ASSERT_ERR(err, "prog_call__load"))
+		prog_call__destroy(skel);
+}
+
+void test_prog_call(void)
+{
+	if (test__start_subtest("single_main_prog"))
+		test_nest_prog_call(0);
+	if (test__start_subtest("sub_prog"))
+		test_nest_prog_call(1);
+	if (test__start_subtest("callback_fn"))
+		test_nest_prog_call(2);
+	if (test__start_subtest("with_tailcall"))
+		test_prog_call_with_tailcall();
+}
diff --git a/tools/testing/selftests/bpf/progs/prog_call.c b/tools/testing/selftests/bpf/progs/prog_call.c
new file mode 100644
index 000000000000..c494cfcf653b
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/prog_call.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+
+struct {
+	__uint(type, BPF_MAP_TYPE_PROG_ARRAY);
+	__uint(max_entries, 3);
+	__uint(key_size, sizeof(__u32));
+	__uint(value_size, sizeof(__u32));
+} jmp_table SEC(".maps");
+
+struct callback_ctx {
+	struct __sk_buff *skb;
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, 1);
+	__type(key, __u32);
+	__type(value, __u64);
+} arraymap SEC(".maps");
+
+int vali, valj;
+
+int glb;
+__noinline static void subprog2(volatile int *a)
+{
+	glb = a[20] + a[10];
+}
+
+__noinline static void subprog1(struct __sk_buff *skb)
+{
+	volatile int a[100] = {};
+
+	a[10] = vali;
+	subprog2(a);
+	vali++;
+	bpf_prog_call(skb, (struct bpf_map *)&jmp_table, 0);
+	valj += a[10];
+}
+
+SEC("?tc")
+int entry_no_subprog(struct __sk_buff *skb)
+{
+	volatile int a[100] = {};
+
+	a[10] = vali;
+	subprog2(a);
+	vali++;
+	bpf_prog_call(skb, (struct bpf_map *)&jmp_table, 0);
+	valj += a[10];
+	return 0;
+}
+
+SEC("?tc")
+int entry_subprog(struct __sk_buff *skb)
+{
+	subprog1(skb);
+	return 0;
+}
+
+static __u64
+check_array_elem(struct bpf_map *map, __u32 *key, __u64 *val,
+		 struct callback_ctx *data)
+{
+	subprog1(data->skb);
+	return 0;
+}
+
+SEC("?tc")
+int entry_callback(struct __sk_buff *skb)
+{
+	struct callback_ctx data;
+
+	data.skb = skb;
+	bpf_for_each_map_elem(&arraymap, check_array_elem, &data, 0);
+	return 0;
+}
+
+SEC("?tc")
+int entry_tail_call(struct __sk_buff *skb)
+{
+	struct callback_ctx data;
+
+	bpf_tail_call_static(skb, &jmp_table, 0);
+
+	data.skb = skb;
+	bpf_for_each_map_elem(&arraymap, check_array_elem, &data, 0);
+	return 0;
+}
+
+char __license[] SEC("license") = "GPL";
-- 
2.43.5