[PATCH bpf-next v8 22/22] selftests/bpf: Load an exception cleanup program from a light skeleton

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

For a light skeleton, libbpf hands the records to bpf_gen__prog_load(),
which writes them into a blob and emits a loader program that issues
BPF_PROG_LOAD from inside the kernel. Nothing about that is shared with the
ordinary path: the attr is built field by field, and the kfunc names are
resolved by the loader program when it runs.

So build progs/exceptions_cleanup.c as a light skeleton too, and run
the case where foo3 unwinds through it, which runs every pad. Its table
has several records, all inside subprograms: a table that loses some, or
lays them out at the wrong stride, does not load, and one whose offsets
come out wrong runs the wrong pads, which pads_ran shows.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
---
 tools/testing/selftests/bpf/Makefile.skel     |  2 +-
 .../bpf/prog_tests/exceptions_cleanup.c       | 31 +++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/Makefile.skel b/tools/testing/selftests/bpf/Makefile.skel
index 2e22bb901bf3..76cd4561dd7a 100644
--- a/tools/testing/selftests/bpf/Makefile.skel
+++ b/tools/testing/selftests/bpf/Makefile.skel
@@ -39,7 +39,7 @@ LSKELS_SIGNED := fentry_test.c fexit_test.c atomics.c
 
 # Generate both light skeleton and libbpf skeleton for these
 LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \
-	kfunc_call_test_subprog.c test_global_percpu_data.c
+	kfunc_call_test_subprog.c test_global_percpu_data.c exceptions_cleanup.c
 SKEL_BLACKLIST += $(LSKELS) $(LSKELS_SIGNED)
 
 test_static_linked.skel.h-deps := test_static_linked1.bpf.o test_static_linked2.bpf.o
diff --git a/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c b/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c
index c06ec10359b9..bb2bb8976fd9 100644
--- a/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c
+++ b/tools/testing/selftests/bpf/prog_tests/exceptions_cleanup.c
@@ -5,6 +5,7 @@
 #include "exceptions_cleanup.skel.h"
 #include "exceptions_cleanup_fail.skel.h"
 #include "exceptions_cleanup_shapes.skel.h"
+#include "exceptions_cleanup.lskel.h"
 
 /* foo3 unwound: every frame that has a pad ran it. */
 #define PADS_FOO3_UNWOUND \
@@ -37,6 +38,33 @@ static void run(struct exceptions_cleanup *skel, __u64 input, __u32 retval,
 	ASSERT_EQ(skel->bss->pads_ran, pads | RAN_BUMP, "pads_ran");
 }
 
+static void test_light_skeleton(void)
+{
+	struct exceptions_cleanup_lskel *skel;
+	__u64 ctx = 0;
+	int err;
+
+	LIBBPF_OPTS(bpf_test_run_opts, topts,
+		    .ctx_in = &ctx,
+		    .ctx_size_in = sizeof(ctx),
+	);
+
+	skel = exceptions_cleanup_lskel__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "light open_and_load"))
+		return;
+
+	/* foo3 unwinds, so every pad runs: the whole table has to arrive. */
+	skel->bss->input = 101;
+	err = bpf_prog_test_run_opts(skel->progs.entry.prog_fd, &topts);
+	if (!ASSERT_OK(err, "run"))
+		goto out;
+	ASSERT_EQ(topts.retval, 0, "retval");
+	ASSERT_EQ(skel->bss->pads_ran, PADS_FOO3_UNWOUND | RAN_BUMP,
+		  "pads_ran");
+out:
+	exceptions_cleanup_lskel__destroy(skel);
+}
+
 void test_exceptions_cleanup(void)
 {
 	char log[8192] = {};
@@ -82,6 +110,9 @@ void test_exceptions_cleanup(void)
 
 	exceptions_cleanup__destroy(skel);
 
+	if (test__start_subtest("light_skeleton"))
+		test_light_skeleton();
+
 	RUN_TESTS(exceptions_cleanup_fail);
 	RUN_TESTS(exceptions_cleanup_shapes);
 }
-- 
2.53.0-Meta