[PATCH bpf-next v3 4/4] selftests/bpf: Add test case for freplace attachment failure logging

[Leon Hwang <leon.hwang@linux.dev>]

This patch adds a selftest to verify that freplace attachment failure
produces meaningful logs.

cd tools/testing/selftests/bpf/; ./test_progs -t attach_log -v
test_freplace_attach_log:PASS:tailcall_bpf2bpf1__open_and_load 0 nsec
test_freplace_attach_log:PASS:freplace_global_func__open 0 nsec
test_freplace_attach_log:PASS:bpf_program__set_attach_target 0 nsec
test_freplace_attach_log:PASS:freplace_global_func__load 0 nsec
libbpf: prog 'new_test_pkt_access': failed to attach to freplace: -EINVAL
libbpf: prog 'new_test_pkt_access': attach log: subprog_tail() is not a global function
test_freplace_attach_log:PASS:bpf_program__attach_freplace 0 nsec
114     freplace_attach_log:OK
Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
 .../bpf/prog_tests/tracing_link_attach_log.c  | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/tracing_link_attach_log.c

diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_link_attach_log.c b/tools/testing/selftests/bpf/prog_tests/tracing_link_attach_log.c
new file mode 100644
index 0000000000000..cfdcb9ebdd255
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_link_attach_log.c
@@ -0,0 +1,42 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright Leon Hwang */
+
+#include <test_progs.h>
+#include "tailcall_bpf2bpf1.skel.h"
+#include "freplace_global_func.skel.h"
+
+void test_freplace_attach_log(void)
+{
+	struct freplace_global_func *freplace_skel = NULL;
+	struct tailcall_bpf2bpf1 *tailcall_skel = NULL;
+	struct bpf_link *freplace_link = NULL;
+	struct bpf_program *prog;
+	int err, prog_fd;
+	LIBBPF_OPTS(bpf_link_create_opts, link_opts);
+
+	tailcall_skel = tailcall_bpf2bpf1__open_and_load();
+	if (!ASSERT_OK_PTR(tailcall_skel, "tailcall_bpf2bpf1__open_and_load"))
+		return;
+
+	freplace_skel = freplace_global_func__open();
+	if (!ASSERT_OK_PTR(freplace_skel, "freplace_global_func__open"))
+		goto out;
+
+	prog = freplace_skel->progs.new_test_pkt_access;
+	prog_fd = bpf_program__fd(tailcall_skel->progs.entry);
+	err = bpf_program__set_attach_target(prog, prog_fd, "entry");
+	if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
+		goto out;
+
+	err = freplace_global_func__load(freplace_skel);
+	if (!ASSERT_OK(err, "freplace_global_func__load"))
+		goto out;
+
+	freplace_link = bpf_program__attach_freplace(prog, prog_fd, "subprog_tail");
+	ASSERT_ERR_PTR(freplace_link, "bpf_program__attach_freplace");
+
+out:
+	bpf_link__destroy(freplace_link);
+	freplace_global_func__destroy(freplace_skel);
+	tailcall_bpf2bpf1__destroy(tailcall_skel);
+}
-- 
2.47.1