selftests/bpf: Add lskel version of kfunc test.

Add light skeleton version of kfunc_call_test_subprog test.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-13-alexei.starovoitov@gmail.com

tools/testing/selftests/bpf/Makefile

@@ -327,7 +327,7 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h		\
 LSKELS := kfunc_call_test.c fentry_test.c fexit_test.c fexit_sleep.c \
 	test_ringbuf.c atomics.c trace_printk.c trace_vprintk.c
 # Generate both light skeleton and libbpf skeleton for these
-LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c
+LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test_subprog.c
 SKEL_BLACKLIST += $$(LSKELS)
 
 test_static_linked.skel.h-deps := test_static_linked1.o test_static_linked2.o

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

@@ -4,6 +4,7 @@
 #include <network_helpers.h>
 #include "kfunc_call_test.lskel.h"
 #include "kfunc_call_test_subprog.skel.h"
+#include "kfunc_call_test_subprog.lskel.h"
 
 static void test_main(void)
 {
@@ -49,6 +50,26 @@ static void test_subprog(void)
 	kfunc_call_test_subprog__destroy(skel);
 }
 
+static void test_subprog_lskel(void)
+{
+	struct kfunc_call_test_subprog_lskel *skel;
+	int prog_fd, retval, err;
+
+	skel = kfunc_call_test_subprog_lskel__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "skel"))
+		return;
+
+	prog_fd = skel->progs.kfunc_call_test1.prog_fd;
+	err = bpf_prog_test_run(prog_fd, 1, &pkt_v4, sizeof(pkt_v4),
+				NULL, NULL, (__u32 *)&retval, NULL);
+	ASSERT_OK(err, "bpf_prog_test_run(test1)");
+	ASSERT_EQ(retval, 10, "test1-retval");
+	ASSERT_NEQ(skel->data->active_res, -1, "active_res");
+	ASSERT_EQ(skel->data->sk_state_res, BPF_TCP_CLOSE, "sk_state_res");
+
+	kfunc_call_test_subprog_lskel__destroy(skel);
+}
+
 void test_kfunc_call(void)
 {
 	if (test__start_subtest("main"))
@@ -56,4 +77,7 @@ void test_kfunc_call(void)
 
 	if (test__start_subtest("subprog"))
 		test_subprog();
+
+	if (test__start_subtest("subprog_lskel"))
+		test_subprog_lskel();
 }