Only fill methods with 0xFE on debug builds
The GC scans classes without holding any locks, we can not fill
the methods if it is running. Added a GC critical section to address
this. Fixes random crash when scanning classes' methods.
Only for debug builds to not hurt performance.
Bug: 28699001
Change-Id: If96155eaf3fc0e6df31f57dcf32fbd4063b09345
diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 649fd6e..26885ac 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -52,6 +52,7 @@
#include "gc/accounting/card_table-inl.h"
#include "gc/accounting/heap_bitmap-inl.h"
#include "gc/heap.h"
+#include "gc/scoped_gc_critical_section.h"
#include "gc/space/image_space.h"
#include "handle_scope-inl.h"
#include "image-inl.h"
@@ -6980,8 +6981,13 @@
}
}
// Put some random garbage in old methods to help find stale pointers.
- if (methods != old_methods && old_methods != nullptr) {
- WriterMutexLock mu(self, ClassTableForClassLoader(klass->GetClassLoader())->GetLock());
+ if (methods != old_methods && old_methods != nullptr && kIsDebugBuild) {
+ // Need to make sure the GC is not running since it could be scanning the methods we are
+ // about to overwrite.
+ ScopedThreadStateChange tsc(self, kSuspended);
+ gc::ScopedGCCriticalSection gcs(self,
+ gc::kGcCauseClassLinker,
+ gc::kCollectorTypeClassLinker);
memset(old_methods, 0xFEu, old_size);
}
} else {
diff --git a/runtime/gc/collector_type.h b/runtime/gc/collector_type.h
index ae41226..a06ccbe 100644
--- a/runtime/gc/collector_type.h
+++ b/runtime/gc/collector_type.h
@@ -47,6 +47,8 @@
// A homogeneous space compaction collector used in background transition
// when both foreground and background collector are CMS.
kCollectorTypeHomogeneousSpaceCompact,
+ // Class linker fake collector.
+ kCollectorTypeClassLinker,
};
std::ostream& operator<<(std::ostream& os, const CollectorType& collector_type);
diff --git a/runtime/gc/gc_cause.cc b/runtime/gc/gc_cause.cc
index 679432b..1b03460 100644
--- a/runtime/gc/gc_cause.cc
+++ b/runtime/gc/gc_cause.cc
@@ -35,6 +35,7 @@
case kGcCauseTrim: return "HeapTrim";
case kGcCauseInstrumentation: return "Instrumentation";
case kGcCauseAddRemoveAppImageSpace: return "AddRemoveAppImageSpace";
+ case kGcCauseClassLinker: return "ClassLinker";
default:
LOG(FATAL) << "Unreachable";
UNREACHABLE();
diff --git a/runtime/gc/gc_cause.h b/runtime/gc/gc_cause.h
index c6b505c..df3aba9 100644
--- a/runtime/gc/gc_cause.h
+++ b/runtime/gc/gc_cause.h
@@ -45,6 +45,8 @@
kGcCauseAddRemoveAppImageSpace,
// GC triggered for background transition when both foreground and background collector are CMS.
kGcCauseHomogeneousSpaceCompact,
+ // Class linker cause, used to guard filling art methods with special values.
+ kGcCauseClassLinker,
};
const char* PrettyCause(GcCause cause);
diff --git a/runtime/gc/scoped_gc_critical_section.cc b/runtime/gc/scoped_gc_critical_section.cc
index e7786a1..b5eb979 100644
--- a/runtime/gc/scoped_gc_critical_section.cc
+++ b/runtime/gc/scoped_gc_critical_section.cc
@@ -38,4 +38,3 @@
} // namespace gc
} // namespace art
-
