netdev - [PATCH 1/2] selftests/bpf: ksym_search won't check symbols exists

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Message-Id: <20190315064210.18735-1-danieltimlee@gmail.com>
Date:   Fri, 15 Mar 2019 15:42:09 +0900
From:   "Daniel T. Lee" <danieltimlee@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>
Cc:     netdev@...r.kernel.org
Subject: [PATCH 1/2] selftests/bpf: ksym_search won't check symbols exists

Currently, ksym_search located at trace_helpers won't check symbols are
existing or not.

In ksym_search, when symbol is not found, it will return &syms[0](_stext).
But when the kernel symbols are not loaded, it will return NULL, which is
not a desired action.

This commit will add verification logic whether symbols are loaded prior
to the symbol search.

Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
---
 tools/testing/selftests/bpf/trace_helpers.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 4cdb63bf0521..9a9fc6c9b70b 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -52,6 +52,10 @@ struct ksym *ksym_search(long key)
 	int start = 0, end = sym_cnt;
 	int result;
 
+	/* kallsyms not loaded. return NULL */
+	if (sym_cnt <= 0)
+		return NULL;
+
 	while (start < end) {
 		size_t mid = start + (end - start) / 2;
 
-- 
2.17.1