[RFC PATCH bpf-next 5/5] selftests/bpf: Add case to test freplace attach failure log

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

Test the new libbpf API 'bpf_program__attach_freplace_log()':

 cd tools/testing/selftests/bpf/
 ./test_progs -t tracing_failure/freplace_attach_log
 #468/3   tracing_failure/freplace_attach_log:OK
 #468     tracing_failure:OK
 Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
---
 .../bpf/prog_tests/tracing_failure.c          | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
index a222df765bc3..05c3a5a9db2a 100644
--- a/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
+++ b/tools/testing/selftests/bpf/prog_tests/tracing_failure.c
@@ -2,6 +2,8 @@
 /* Copyright (c) 2024 Meta Platforms, Inc. and affiliates. */
 #include <test_progs.h>
 #include "tracing_failure.skel.h"
+#include "tailcall_bpf2bpf1.skel.h"
+#include "freplace_global_func.skel.h"
 
 static void test_bpf_spin_lock(bool is_spin_lock)
 {
@@ -28,10 +30,51 @@ static void test_bpf_spin_lock(bool is_spin_lock)
 	tracing_failure__destroy(skel);
 }
 
+static 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;
+	char log_buf[64];
+	int err, prog_fd;
+
+	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;
+
+	log_buf[0] = '\0';
+	freplace_link = bpf_program__attach_freplace_log(prog, prog_fd, "subprog_tail", log_buf,
+							 sizeof(log_buf));
+	ASSERT_ERR_PTR(freplace_link, "bpf_program__attach_freplace_log");
+	ASSERT_STREQ(log_buf, "subprog_tail() is not a global function\n", "log_buf");
+
+out:
+	bpf_link__destroy(freplace_link);
+	freplace_global_func__destroy(freplace_skel);
+	tailcall_bpf2bpf1__destroy(tailcall_skel);
+}
+
 void test_tracing_failure(void)
 {
 	if (test__start_subtest("bpf_spin_lock"))
 		test_bpf_spin_lock(true);
 	if (test__start_subtest("bpf_spin_unlock"))
 		test_bpf_spin_lock(false);
+	if (test__start_subtest("freplace_attach_log"))
+		test_freplace_attach_log();
 }
-- 
2.50.1