selftests/bpf: Add __noinline variant of cls_redirect selftest

As one of the most complicated and close-to-real-world programs, cls_redirect
is a good candidate to exercise libbpf's logic of handling bpf2bpf calls. So
add variant with using explicit __noinline for majority of functions except
few most basic ones. If those few functions are inlined, verifier starts to
complain about program instruction limit of 1mln instructions being exceeded,
most probably due to instruction overhead of doing a sub-program call.
Convert user-space part of selftest to have to sub-tests: with and without
inlining.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Link: https://lore.kernel.org/bpf/20200903203542.15944-15-andriin@fb.com

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

@@ -12,10 +12,13 @@
 
 #include "progs/test_cls_redirect.h"
 #include "test_cls_redirect.skel.h"
+#include "test_cls_redirect_subprogs.skel.h"
 
 #define ENCAP_IP INADDR_LOOPBACK
 #define ENCAP_PORT (1234)
 
+static int duration = 0;
+
 struct addr_port {
 	in_port_t port;
 	union {
@@ -361,30 +364,18 @@ static void close_fds(int *fds, int n)
 			close(fds[i]);
 }
 
-void test_cls_redirect(void)
+static void test_cls_redirect_common(struct bpf_program *prog)
 {
-	struct test_cls_redirect *skel = NULL;
 	struct bpf_prog_test_run_attr tattr = {};
 	int families[] = { AF_INET, AF_INET6 };
 	struct sockaddr_storage ss;
 	struct sockaddr *addr;
 	socklen_t slen;
 	int i, j, err;
-
 	int servers[__NR_KIND][ARRAY_SIZE(families)] = {};
 	int conns[__NR_KIND][ARRAY_SIZE(families)] = {};
 	struct tuple tuples[__NR_KIND][ARRAY_SIZE(families)];
 
-	skel = test_cls_redirect__open();
-	if (CHECK_FAIL(!skel))
-		return;
-
-	skel->rodata->ENCAPSULATION_IP = htonl(ENCAP_IP);
-	skel->rodata->ENCAPSULATION_PORT = htons(ENCAP_PORT);
-
-	if (CHECK_FAIL(test_cls_redirect__load(skel)))
-		goto cleanup;
-
 	addr = (struct sockaddr *)&ss;
 	for (i = 0; i < ARRAY_SIZE(families); i++) {
 		slen = prepare_addr(&ss, families[i]);
@@ -402,7 +393,7 @@ void test_cls_redirect(void)
 			goto cleanup;
 	}
 
-	tattr.prog_fd = bpf_program__fd(skel->progs.cls_redirect);
+	tattr.prog_fd = bpf_program__fd(prog);
 	for (i = 0; i < ARRAY_SIZE(tests); i++) {
 		struct test_cfg *test = &tests[i];
 
@@ -450,7 +441,58 @@ void test_cls_redirect(void)
 	}
 
 cleanup:
-	test_cls_redirect__destroy(skel);
 	close_fds((int *)servers, sizeof(servers) / sizeof(servers[0][0]));
 	close_fds((int *)conns, sizeof(conns) / sizeof(conns[0][0]));
 }
+
+static void test_cls_redirect_inlined(void)
+{
+	struct test_cls_redirect *skel;
+	int err;
+
+	skel = test_cls_redirect__open();
+	if (CHECK(!skel, "skel_open", "failed\n"))
+		return;
+
+	skel->rodata->ENCAPSULATION_IP = htonl(ENCAP_IP);
+	skel->rodata->ENCAPSULATION_PORT = htons(ENCAP_PORT);
+
+	err = test_cls_redirect__load(skel);
+	if (CHECK(err, "skel_load", "failed: %d\n", err))
+		goto cleanup;
+
+	test_cls_redirect_common(skel->progs.cls_redirect);
+
+cleanup:
+	test_cls_redirect__destroy(skel);
+}
+
+static void test_cls_redirect_subprogs(void)
+{
+	struct test_cls_redirect_subprogs *skel;
+	int err;
+
+	skel = test_cls_redirect_subprogs__open();
+	if (CHECK(!skel, "skel_open", "failed\n"))
+		return;
+
+	skel->rodata->ENCAPSULATION_IP = htonl(ENCAP_IP);
+	skel->rodata->ENCAPSULATION_PORT = htons(ENCAP_PORT);
+
+	err = test_cls_redirect_subprogs__load(skel);
+	if (CHECK(err, "skel_load", "failed: %d\n", err))
+		goto cleanup;
+
+	test_cls_redirect_common(skel->progs.cls_redirect);
+
+cleanup:
+	test_cls_redirect_subprogs__destroy(skel);
+}
+
+void test_cls_redirect(void)
+{
+	if (test__start_subtest("cls_redirect_inlined"))
+		test_cls_redirect_inlined();
+	if (test__start_subtest("cls_redirect_subprogs"))
+		test_cls_redirect_subprogs();
+}

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

+#define SUBPROGS
+#include "test_cls_redirect.c"