Stability instrumentation: add a Vectored Exception Handler

components/browser_watcher/stability_debugging.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/browser_watcher/stability_debugging.h"
 
+#include <windows.h>
+
+#include <memory>
+
 #include "base/debug/activity_tracker.h"
+#include "build/build_config.h"
 
 namespace browser_watcher {
 
+namespace {
+
+struct VehUnregisterer {
+  void operator()(void* handle) const {
+    ::RemoveVectoredExceptionHandler(handle);
+  }
+};
+
+using VehHandle = std::unique_ptr<void, VehUnregisterer>;
+
+uintptr_t GetProgramCounter(const CONTEXT& context) {
+#if defined(ARCH_CPU_X86)
+  return context.Eip;
+#elif defined(ARCH_CPU_X86_64)
+  return context.Rip;
+#endif
+}
+
+LONG CALLBACK VectoredExceptionHandler(EXCEPTION_POINTERS* exception_pointers) {
+  base::debug::GlobalActivityTracker* tracker =
+      base::debug::GlobalActivityTracker::Get();
+  if (tracker) {
+    EXCEPTION_RECORD* record = exception_pointers->ExceptionRecord;
+    uintptr_t pc = GetProgramCounter(*exception_pointers->ContextRecord);
+    tracker->RecordException(reinterpret_cast<void*>(pc),
+                             record->ExceptionAddress, record->ExceptionCode);
+  }
+
+  return EXCEPTION_CONTINUE_SEARCH;  // Continue to the next handler.
+}
+
+}  // namespace
+
 void SetStabilityDataBool(base::StringPiece name, bool value) {
   base::debug::GlobalActivityTracker* global_tracker =
       base::debug::GlobalActivityTracker::Get();
   if (!global_tracker)
     return;  // Activity tracking isn't enabled.
 
   global_tracker->process_data().SetBool(name, value);
 }
 
 void SetStabilityDataInt(base::StringPiece name, int64_t value) {
   base::debug::GlobalActivityTracker* global_tracker =
       base::debug::GlobalActivityTracker::Get();
   if (!global_tracker)
     return;  // Activity tracking isn't enabled.
 
   global_tracker->process_data().SetInt(name, value);
 }
 
+void RegisterStabilityVEH() {
+  // Register a vectored exception handler and request it be first. Note that
+  // subsequent registrations may also request to be first, in which case this
+  // one will be bumped.
+  // TODO(manzagop): Depending on observations, it may be necessary to
+  // consider refreshing the registration, either periodically or at opportune
+  // (e.g. risky) times.
+  static VehHandle veh_handler(
+      ::AddVectoredExceptionHandler(1, &VectoredExceptionHandler));
+  DCHECK(veh_handler);
+}
+
 }  // namespace browser_watcher