[PATCH v4 bpf-next 17/17] selftests/bpf: update btf_module test to ensure standalone BTF works

[Alan Maguire <alan.maguire@xxxxxxxxxx>]

btf_module test verifies that loading split BTF from bpf_testmod.ko
is successful.  To test standalone BTF, add a test that loads
BTF from bpf_testmod_standalone.ko and verifies we can look up BTF,
just as we could for real split BTF.

Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
---
 tools/testing/selftests/bpf/Makefile          |  8 ++++----
 .../selftests/bpf/prog_tests/btf_module.c     | 19 +++++++++++++++++--
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 9c27b67bc7b1..5a4421238d5b 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -106,7 +106,7 @@ TEST_GEN_PROGS_EXTENDED = test_sock_addr test_skb_cgroup_id_user \
 	flow_dissector_load test_flow_dissector test_tcp_check_syncookie_user \
 	test_lirc_mode2_user xdping test_cpp runqslower bench bpf_testmod.ko \
 	xskxceiver xdp_redirect_multi xdp_synproxy veristat xdp_hw_metadata \
-	xdp_features
+	xdp_features btf_testmod_standalone.ko
 
 TEST_GEN_FILES += liburandom_read.so urandom_read sign-file uprobe_multi
 
@@ -225,9 +225,9 @@ $(OUTPUT)/sign-file: ../../../../scripts/sign-file.c
 
 $(OUTPUT)/bpf_testmod.ko: $(VMLINUX_BTF) $(RESOLVE_BTFIDS) $(wildcard bpf_testmod/Makefile bpf_testmod/*.[ch])
 	$(call msg,MOD,,$@)
-	$(Q)$(RM) bpf_testmod/bpf_testmod.ko # force re-compilation
+	$(Q)$(RM) bpf_testmod/bpf_testmod*.ko # force re-compilation
 	$(Q)$(MAKE) $(submake_extras) RESOLVE_BTFIDS=$(RESOLVE_BTFIDS) -C bpf_testmod
-	$(Q)cp bpf_testmod/bpf_testmod.ko $@
+	$(Q)cp bpf_testmod/bpf_testmod*.ko $(OUTPUT)
 
 DEFAULT_BPFTOOL := $(HOST_SCRATCH_DIR)/sbin/bpftool
 ifneq ($(CROSS_COMPILE),)
@@ -728,7 +728,7 @@ EXTRA_CLEAN := $(TEST_CUSTOM_PROGS) $(SCRATCH_DIR) $(HOST_SCRATCH_DIR)	\
 	prog_tests/tests.h map_tests/tests.h verifier/tests.h		\
 	feature bpftool							\
 	$(addprefix $(OUTPUT)/,*.o *.skel.h *.lskel.h *.subskel.h	\
-			       no_alu32 cpuv4 bpf_gcc bpf_testmod.ko	\
+			       no_alu32 cpuv4 bpf_gcc bpf_testmod*.ko	\
 			       liburandom_read.so)
 
 .PHONY: docs docs-clean
diff --git a/tools/testing/selftests/bpf/prog_tests/btf_module.c b/tools/testing/selftests/bpf/prog_tests/btf_module.c
index 2239d1fe0332..5470342a1d08 100644
--- a/tools/testing/selftests/bpf/prog_tests/btf_module.c
+++ b/tools/testing/selftests/bpf/prog_tests/btf_module.c
@@ -5,11 +5,13 @@
 #include <bpf/btf.h>
 
 static const char *module_name = "bpf_testmod";
+static const char *standalone_module_name = "bpf_testmod_standalone";
 static const char *symbol_name = "bpf_testmod_test_read";
+static const char *standalone_symbol_name = "bpf_testmod_standalone_test_read";
 
 void test_btf_module()
 {
-	struct btf *vmlinux_btf, *module_btf;
+	struct btf *vmlinux_btf, *module_btf, *standalone_module_btf = NULL;
 	__s32 type_id;
 
 	if (!env.has_testmod) {
@@ -26,9 +28,22 @@ void test_btf_module()
 		goto cleanup;
 
 	type_id = btf__find_by_name(module_btf, symbol_name);
-	ASSERT_GT(type_id, 0, "func not found");
+	if (!ASSERT_GT(type_id, 0, "func not found"))
+		goto cleanup;
+
+	if (!ASSERT_OK(load_bpf_testmod(standalone_module_name, false), "load standalone BTF module"))
+		goto cleanup;
+
+	standalone_module_btf = btf__load_module_btf(standalone_module_name, vmlinux_btf);
+	if (!ASSERT_OK_PTR(standalone_module_btf, "could not load standalone module BTF"))
+		goto cleanup;
+
+	type_id = btf__find_by_name(standalone_module_btf, standalone_symbol_name);
+	ASSERT_GT(type_id, 0, "func not found in standalone");
 
 cleanup:
+	btf__free(standalone_module_btf);
 	btf__free(module_btf);
 	btf__free(vmlinux_btf);
+	unload_bpf_testmod(standalone_module_name, false);
 }
-- 
2.31.1