simpleperf: fix CanRecordRawData.

sys.init.perf_lsm_hooks isn't accessible in app context, thus
checking it in CanRecordRawData() breaks recording app with
--trace-offcpu option.

Fix it by not recording raw data in non-root users.

Bug: 153381808
Test: run simpleperf_unit_test.
Test: run test.py *TraceOffCpu*.
Change-Id: Id87c73d25b19b265c022c4fa6ebb8e7d3a84152b

1 files changed, 7 insertions, 10 deletions

diff --git a/simpleperf/environment.cpp b/simpleperf/environment.cpp
index e16e496f..5b2fcaa8 100644
--- a/simpleperf/environment.cpp
+++ b/simpleperf/environment.cpp
@@ -299,18 +299,15 @@ bool CanRecordRawData() {
   if (IsRoot()) {
     return true;
   }
-  int value;
-  if (!ReadPerfEventParanoid(&value) || value > -1) {
-    return false;
-  }
 #if defined(__ANDROID__)
-  // If perf_event_open() is controlled by selinux, simpleperf can't record tracepoint raw data
-  // unless running as root.
-  if (android::base::GetProperty("sys.init.perf_lsm_hooks", "") == "1") {
-    return false;
-  }
+  // Android R uses selinux to control perf_event_open. Whether raw data can be recorded is hard
+  // to check unless we really try it. And probably there is no need to record raw data in non-root
+  // users.
+  return false;
+#else
+  int value;
+  return ReadPerfEventParanoid(&value) && value == -1;
 #endif
-  return true;
 }
 
 static const char* GetLimitLevelDescription(int limit_level) {