Avoid instrumentation stack corruption.

While debugging a throwing exception, we may end up updating instrumentation
stack frame after having already walked the native stack. This leads to not pop
instrumentation frames prior to catch handler (or upcall if exception is not
caught) and get it desynchronized with the native stack.

To solve this issue, we need to walk the stack again after having reporting the
exception to the instrumentation listener (for example: the debugger) which
may push new instrumentation stack frames. However we do it only when we know
instrumentation is enabled to not slow down exception delivery when executing
code without instrumentation.

Here are the main changes:
- Creates InstrumentationStackVisitor to compute the number of instrumentation
frames to pop (previously done in CatchBlockStackVisitor). We only count frames
prior to catch handler (or upcall). Popping instrumentation frames is done
after having reported the exception to the instrumentation listener.
- Updates the CatchBlockStackVisitor to remove instrumentation frame handling
and focus only on finding the catch handler and prepare deoptimization.
- Creates CatchFinder class to control both visitors and do the long jump.

Change-Id: I29b3871403f297bfb8c087e27f1330b002f5d56d

1 files changed, 95 insertions, 0 deletions

diff --git a/runtime/catch_finder.h b/runtime/catch_finder.h
new file mode 100644
index 0000000..ebbafe2
--- /dev/null
+++ b/runtime/catch_finder.h
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_CATCH_FINDER_H_
+#define ART_RUNTIME_CATCH_FINDER_H_
+
+#include "mirror/art_method-inl.h"
+#include "thread.h"
+
+namespace art {
+
+static constexpr bool kDebugExceptionDelivery = false;
+static constexpr size_t kInvalidFrameId = 0xffffffff;
+
+// Manages exception delivery for Quick backend. Not used by Portable backend.
+class CatchFinder {
+ public:
+  CatchFinder(Thread* self, const ThrowLocation& throw_location, mirror::Throwable* exception,
+              bool is_deoptimization)
+      SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
+  ~CatchFinder() {
+    LOG(FATAL) << "UNREACHABLE";  // Expected to take long jump.
+  }
+
+  void FindCatch() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+  void UpdateInstrumentationStack() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+  void DoLongJump() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
+
+  void SetHandlerQuickFrame(mirror::ArtMethod** handler_quick_frame) {
+    handler_quick_frame_ = handler_quick_frame;
+  }
+
+  void SetHandlerQuickFramePc(uintptr_t handler_quick_frame_pc) {
+    handler_quick_frame_pc_ = handler_quick_frame_pc;
+  }
+
+  void SetHandlerDexPc(uint32_t dex_pc) {
+    handler_dex_pc_ = dex_pc;
+  }
+
+  void SetClearException(bool clear_exception) {
+    clear_exception_ = clear_exception;
+  }
+
+  void SetTopShadowFrame(ShadowFrame* top_shadow_frame) {
+    top_shadow_frame_ = top_shadow_frame;
+  }
+
+  void SetHandlerFrameId(size_t frame_id) {
+    handler_frame_id_ = frame_id;
+  }
+
+ private:
+  Thread* const self_;
+  Context* const context_;
+  mirror::Throwable* const exception_;
+  const bool is_deoptimization_;
+  // Location of the throw.
+  const ThrowLocation& throw_location_;
+  // Is method tracing active?
+  const bool method_tracing_active_;
+  // Support for nesting no thread suspension checks.
+  const char* last_no_assert_suspension_cause_;
+  // Quick frame with found handler or last frame if no handler found.
+  mirror::ArtMethod** handler_quick_frame_;
+  // PC to branch to for the handler.
+  uintptr_t handler_quick_frame_pc_;
+  // Associated dex PC.
+  uint32_t handler_dex_pc_;
+  // Should the exception be cleared as the catch block has no move-exception?
+  bool clear_exception_;
+  // Deoptimization top shadow frame.
+  ShadowFrame* top_shadow_frame_;
+  // Frame id of the catch handler or the upcall.
+  size_t handler_frame_id_;
+
+  DISALLOW_COPY_AND_ASSIGN(CatchFinder);
+};
+
+}  // namespace art
+#endif  // ART_RUNTIME_CATCH_FINDER_H_