linux-kernel - [PATCH bpf-next 5/5] samples/bpf: Handle NULL pointer returned by ksym

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Message-Id: <1524101646-6544-6-git-send-email-leo.yan@linaro.org>
Date:   Thu, 19 Apr 2018 09:34:06 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH bpf-next 5/5] samples/bpf: Handle NULL pointer returned by ksym_search()

This commit handles NULL pointer returned by ksym_search() to directly
print address hexadecimal value, the change is applied in 'trace_event',
'spintest' and 'offwaketime' programs.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
---
 samples/bpf/offwaketime_user.c | 5 +++++
 samples/bpf/spintest_user.c    | 5 ++++-
 samples/bpf/trace_event_user.c | 5 +++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/samples/bpf/offwaketime_user.c b/samples/bpf/offwaketime_user.c
index 512f87a..fce2113 100644
--- a/samples/bpf/offwaketime_user.c
+++ b/samples/bpf/offwaketime_user.c
@@ -27,6 +27,11 @@ static void print_ksym(__u64 addr)
 	if (!addr)
 		return;
 	sym = ksym_search(addr);
+	if (!sym) {
+		printf("%llx;", addr);
+		return;
+	}
+
 	if (PRINT_RAW_ADDR)
 		printf("%s/%llx;", sym->name, addr);
 	else
diff --git a/samples/bpf/spintest_user.c b/samples/bpf/spintest_user.c
index 3d73621..3140803 100644
--- a/samples/bpf/spintest_user.c
+++ b/samples/bpf/spintest_user.c
@@ -36,7 +36,10 @@ int main(int ac, char **argv)
 			bpf_map_lookup_elem(map_fd[0], &next_key, &value);
 			assert(next_key == value);
 			sym = ksym_search(value);
-			printf(" %s", sym->name);
+			if (!sym)
+				printf(" %lx", value);
+			else
+				printf(" %s", sym->name);
 			key = next_key;
 		}
 		if (key)
diff --git a/samples/bpf/trace_event_user.c b/samples/bpf/trace_event_user.c
index 56f7a25..d2ab33e 100644
--- a/samples/bpf/trace_event_user.c
+++ b/samples/bpf/trace_event_user.c
@@ -33,6 +33,11 @@ static void print_ksym(__u64 addr)
 	if (!addr)
 		return;
 	sym = ksym_search(addr);
+	if (!sym) {
+		printf("%llx;", addr);
+		return;
+	}
+
 	printf("%s;", sym->name);
 	if (!strcmp(sym->name, "sys_read"))
 		sys_read_seen = true;
-- 
1.9.1