selftests/bpf: Don't use libbpf_get_error() in kprobe_multi_test

Since libbpf v1.0, libbpf doesn't return error code embedded into the
pointer iteself, libbpf_get_error() is deprecated and it is basically
the same as using -errno directly.

So replace the invocations of libbpf_get_error() by -errno in
kprobe_multi_test. For libbpf_get_error() in test_attach_api_fails(),
saving -errno before invoking ASSERT_xx() macros just in case that
errno is overwritten by these macros. However, the invocation of
libbpf_get_error() in get_syms() should be kept intact, because
hashmap__new() still returns a pointer with embedded error code.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231215100708.2265609-5-houtao@huaweicloud.com

Author: Hou Tao

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

@@ -222,6 +222,7 @@ static void test_attach_api_fails(void)
 		"bpf_fentry_test2",
 	};
 	__u64 cookies[2];
+	int saved_error;
 
 	addrs[0] = ksym_get_addr("bpf_fentry_test1");
 	addrs[1] = ksym_get_addr("bpf_fentry_test2");
@@ -238,10 +239,11 @@ static void test_attach_api_fails(void)
 	/* fail_1 - pattern and opts NULL */
 	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     NULL, NULL);
+	saved_error = -errno;
 	if (!ASSERT_ERR_PTR(link, "fail_1"))
 		goto cleanup;
 
-	if (!ASSERT_EQ(libbpf_get_error(link), -EINVAL, "fail_1_error"))
+	if (!ASSERT_EQ(saved_error, -EINVAL, "fail_1_error"))
 		goto cleanup;
 
 	/* fail_2 - both addrs and syms set */
@@ -252,10 +254,11 @@ static void test_attach_api_fails(void)
 
 	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     NULL, &opts);
+	saved_error = -errno;
 	if (!ASSERT_ERR_PTR(link, "fail_2"))
 		goto cleanup;
 
-	if (!ASSERT_EQ(libbpf_get_error(link), -EINVAL, "fail_2_error"))
+	if (!ASSERT_EQ(saved_error, -EINVAL, "fail_2_error"))
 		goto cleanup;
 
 	/* fail_3 - pattern and addrs set */
@@ -266,10 +269,11 @@ static void test_attach_api_fails(void)
 
 	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     "ksys_*", &opts);
+	saved_error = -errno;
 	if (!ASSERT_ERR_PTR(link, "fail_3"))
 		goto cleanup;
 
-	if (!ASSERT_EQ(libbpf_get_error(link), -EINVAL, "fail_3_error"))
+	if (!ASSERT_EQ(saved_error, -EINVAL, "fail_3_error"))
 		goto cleanup;
 
 	/* fail_4 - pattern and cnt set */
@@ -280,10 +284,11 @@ static void test_attach_api_fails(void)
 
 	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     "ksys_*", &opts);
+	saved_error = -errno;
 	if (!ASSERT_ERR_PTR(link, "fail_4"))
 		goto cleanup;
 
-	if (!ASSERT_EQ(libbpf_get_error(link), -EINVAL, "fail_4_error"))
+	if (!ASSERT_EQ(saved_error, -EINVAL, "fail_4_error"))
 		goto cleanup;
 
 	/* fail_5 - pattern and cookies */
@@ -294,10 +299,11 @@ static void test_attach_api_fails(void)
 
 	link = bpf_program__attach_kprobe_multi_opts(skel->progs.test_kprobe_manual,
 						     "ksys_*", &opts);
+	saved_error = -errno;
 	if (!ASSERT_ERR_PTR(link, "fail_5"))
 		goto cleanup;
 
-	if (!ASSERT_EQ(libbpf_get_error(link), -EINVAL, "fail_5_error"))
+	if (!ASSERT_EQ(saved_error, -EINVAL, "fail_5_error"))
 		goto cleanup;
 
 cleanup: