bpf: Add type cast unit tests

Three tests are added. One is from John Fastabend ({1]) which tests
tracing style access for xdp program from the kernel ctx.
Another is a tc test to test both kernel ctx tracing style access
and explicit non-ctx type cast. The third one is for negative tests
including two tests, a tp_bpf test where the bpf_rdonly_cast()
returns a untrusted ptr which cannot be used as helper argument,
and a tracepoint test where the kernel ctx is a u64.

Also added the test to DENYLIST.s390x since s390 does not currently
support calling kernel functions in JIT mode.

  [1] https://lore.kernel.org/bpf/20221109215242.1279993-1-john.fastabend@gmail.com/

Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221120195442.3114844-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 114 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/type_cast.c b/tools/testing/selftests/bpf/prog_tests/type_cast.c
new file mode 100644
index 000000000000..9317d5fa2635
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/type_cast.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
+#include <test_progs.h>
+#include <network_helpers.h>
+#include "type_cast.skel.h"
+
+static void test_xdp(void)
+{
+	struct type_cast *skel;
+	int err, prog_fd;
+	char buf[128];
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+		.data_in = &pkt_v4,
+		.data_size_in = sizeof(pkt_v4),
+		.data_out = buf,
+		.data_size_out = sizeof(buf),
+		.repeat = 1,
+	);
+
+	skel = type_cast__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.md_xdp, true);
+	err = type_cast__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto out;
+
+	prog_fd = bpf_program__fd(skel->progs.md_xdp);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, XDP_PASS, "xdp test_run retval");
+
+	ASSERT_EQ(skel->bss->ifindex, 1, "xdp_md ifindex");
+	ASSERT_EQ(skel->bss->ifindex, skel->bss->ingress_ifindex, "xdp_md ingress_ifindex");
+	ASSERT_STREQ(skel->bss->name, "lo", "xdp_md name");
+	ASSERT_NEQ(skel->bss->inum, 0, "xdp_md inum");
+
+out:
+	type_cast__destroy(skel);
+}
+
+static void test_tc(void)
+{
+	struct type_cast *skel;
+	int err, prog_fd;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+		.data_in = &pkt_v4,
+		.data_size_in = sizeof(pkt_v4),
+		.repeat = 1,
+	);
+
+	skel = type_cast__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		return;
+
+	bpf_program__set_autoload(skel->progs.md_skb, true);
+	err = type_cast__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto out;
+
+	prog_fd = bpf_program__fd(skel->progs.md_skb);
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+	ASSERT_OK(err, "test_run");
+	ASSERT_EQ(topts.retval, 0, "tc test_run retval");
+
+	ASSERT_EQ(skel->bss->meta_len, 0, "skb meta_len");
+	ASSERT_EQ(skel->bss->frag0_len, 0, "skb frag0_len");
+	ASSERT_NEQ(skel->bss->kskb_len, 0, "skb len");
+	ASSERT_NEQ(skel->bss->kskb2_len, 0, "skb2 len");
+	ASSERT_EQ(skel->bss->kskb_len, skel->bss->kskb2_len, "skb len compare");
+
+out:
+	type_cast__destroy(skel);
+}
+
+static const char * const negative_tests[] = {
+	"untrusted_ptr",
+	"kctx_u64",
+};
+
+static void test_negative(void)
+{
+	struct bpf_program *prog;
+	struct type_cast *skel;
+	int i, err;
+
+	for (i = 0; i < ARRAY_SIZE(negative_tests); i++) {
+		skel = type_cast__open();
+		if (!ASSERT_OK_PTR(skel, "skel_open"))
+			return;
+
+		prog = bpf_object__find_program_by_name(skel->obj, negative_tests[i]);
+		if (!ASSERT_OK_PTR(prog, "bpf_object__find_program_by_name"))
+			goto out;
+		bpf_program__set_autoload(prog, true);
+		err = type_cast__load(skel);
+		ASSERT_ERR(err, "skel_load");
+out:
+		type_cast__destroy(skel);
+	}
+}
+
+void test_type_cast(void)
+{
+	if (test__start_subtest("xdp"))
+		test_xdp();
+	if (test__start_subtest("tc"))
+		test_tc();
+	if (test__start_subtest("negative"))
+		test_negative();
+}