[PATCH] perf tools: Don't try to lookup objdump for live mode

[Namhyung Kim <namhyung@kernel.org>]

From: Namhyung Kim <namhyung.kim@lge.com>

Arnaldo reported that annotation during perf top resulted in a
segfault.  It was because the env->arch was NULL and we don't set it
for a live session.  In fact, no need to look up objdump in this case
since we can use system's default (native) objdump.

Reported-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: Irina Tirdea <irina.tirdea@gmail.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 tools/perf/arch/common.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/perf/arch/common.c b/tools/perf/arch/common.c
index 5683529135b1..3e975cb6232e 100644
--- a/tools/perf/arch/common.c
+++ b/tools/perf/arch/common.c
@@ -199,6 +199,13 @@ out_error:
 
 int perf_session_env__lookup_objdump(struct perf_session_env *env)
 {
+	/*
+	 * For live mode, env->arch will be NULL and we can use
+	 * the native objdump tool.
+	 */
+	if (env->arch == NULL)
+		return 0;
+
 	return perf_session_env__lookup_binutils_path(env, "objdump",
 						      &objdump_path);
 }
-- 
1.7.11.7