[PATCH bpf-next 08/24] selftests/bpf: Fix verify_pkcs7_sig on s390x

[Ilya Leoshkevich <iii@xxxxxxxxxxxxx>]

Use bpf_probe_read_kernel() instead of bpf_probe_read(), which is not
defined on all architectures.

While at it, improve the error handling: do not hide the verifier log,
and check the return values of bpf_probe_read_kernel() and
bpf_copy_from_user().

Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
 .../selftests/bpf/prog_tests/verify_pkcs7_sig.c      |  9 +++++++++
 .../selftests/bpf/progs/test_verify_pkcs7_sig.c      | 12 ++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c b/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c
index 579d6ee83ce0..75c256f79f85 100644
--- a/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c
+++ b/tools/testing/selftests/bpf/prog_tests/verify_pkcs7_sig.c
@@ -56,11 +56,17 @@ struct data {
 	__u32 sig_len;
 };
 
+static char libbpf_log[8192];
 static bool kfunc_not_supported;
 
 static int libbpf_print_cb(enum libbpf_print_level level, const char *fmt,
 			   va_list args)
 {
+	size_t log_len = strlen(libbpf_log);
+
+	vsnprintf(libbpf_log + log_len, sizeof(libbpf_log) - log_len,
+		  fmt, args);
+
 	if (strcmp(fmt, "libbpf: extern (func ksym) '%s': not found in kernel or module BTFs\n"))
 		return 0;
 
@@ -277,6 +283,7 @@ void test_verify_pkcs7_sig(void)
 	if (!ASSERT_OK_PTR(skel, "test_verify_pkcs7_sig__open"))
 		goto close_prog;
 
+	libbpf_log[0] = 0;
 	old_print_cb = libbpf_set_print(libbpf_print_cb);
 	ret = test_verify_pkcs7_sig__load(skel);
 	libbpf_set_print(old_print_cb);
@@ -289,6 +296,8 @@ void test_verify_pkcs7_sig(void)
 		goto close_prog;
 	}
 
+	printf("%s", libbpf_log);
+
 	if (!ASSERT_OK(ret, "test_verify_pkcs7_sig__load"))
 		goto close_prog;
 
diff --git a/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c b/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c
index ce419304ff1f..7748cc23de8a 100644
--- a/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c
+++ b/tools/testing/selftests/bpf/progs/test_verify_pkcs7_sig.c
@@ -59,10 +59,14 @@ int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size)
 	if (!data_val)
 		return 0;
 
-	bpf_probe_read(&value, sizeof(value), &attr->value);
-
-	bpf_copy_from_user(data_val, sizeof(struct data),
-			   (void *)(unsigned long)value);
+	ret = bpf_probe_read_kernel(&value, sizeof(value), &attr->value);
+	if (ret)
+		return ret;
+
+	ret = bpf_copy_from_user(data_val, sizeof(struct data),
+				 (void *)(unsigned long)value);
+	if (ret)
+		return ret;
 
 	if (data_val->data_len > sizeof(data_val->data))
 		return -EINVAL;
-- 
2.39.1