1 files changed, 7 insertions, 95 deletions

diff --git a/runtime/thread.cc b/runtime/thread.cc
index a9173d5..6e8f89c 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -96,11 +96,9 @@ void InitEntryPoints(InterpreterEntryPoints* ipoints, JniEntryPoints* jpoints,
 
 void Thread::InitTlsEntryPoints() {
   // Insert a placeholder so we can easily tell if we call an unimplemented entry point.
-  uintptr_t* begin = reinterpret_cast<uintptr_t*>(&tlsPtr_.quick_entrypoints);
-  uintptr_t* end = reinterpret_cast<uintptr_t*>(
-      reinterpret_cast<uint8_t*>(&tlsPtr_.interpreter_entrypoints) +
-      sizeof(tlsPtr_.interpreter_entrypoints));
-  DCHECK_LT(begin, end);
+  uintptr_t* begin = reinterpret_cast<uintptr_t*>(&tlsPtr_.interpreter_entrypoints);
+  uintptr_t* end = reinterpret_cast<uintptr_t*>(reinterpret_cast<uint8_t*>(&tlsPtr_.quick_entrypoints) +
+      sizeof(tlsPtr_.quick_entrypoints));
   for (uintptr_t* it = begin; it != end; ++it) {
     *it = reinterpret_cast<uintptr_t>(UnimplementedEntryPoint);
   }
@@ -108,90 +106,7 @@ void Thread::InitTlsEntryPoints() {
                   &tlsPtr_.quick_entrypoints);
 }
 
-static constexpr bool kUseWriteProtectScheme = true;
-
-static size_t GetProtectionOffset() {
-  return RoundUp(QUICK_ENTRYPOINT_OFFSET(sizeof(void*), pInstanceofNonTrivial).Uint32Value(), 16);
-}
-
-// Allocate a thread. This might do some magic to use two pages.
-Thread* Thread::AllocateThread(bool is_daemon) {
-  if (!kUseWriteProtectScheme) {
-    return new Thread(is_daemon);
-  }
-
-  std::string error_msg;
-  MemMap* mem_map = MemMap::MapAnonymous("some thread",
-                                         nullptr,
-                                         2 * kPageSize,
-                                         PROT_READ | PROT_WRITE,
-                                         false,
-                                         false,
-                                         &error_msg);
-  if (mem_map == nullptr) {
-    PLOG(FATAL) << error_msg;
-  }
-
-  uint8_t* second_page_address = mem_map->Begin() + kPageSize;
-  const uint32_t offset = GetProtectionOffset();
-  uintptr_t start_address = reinterpret_cast<uintptr_t>(second_page_address) - offset;
-  DCHECK_GE(start_address, reinterpret_cast<uintptr_t>(mem_map->Begin()) + sizeof(void*));
-  void* start_address_ptr = reinterpret_cast<void*>(start_address);
-  Thread* t = new (start_address_ptr) Thread(is_daemon);
-
-  // Store a pointer to the MemMap at the bottom.
-  *reinterpret_cast<MemMap**>(mem_map->Begin()) = mem_map;
-
-  return t;
-}
-
-static void ProtectThread(Thread* thread) {
-  if (!kUseWriteProtectScheme) {
-    return;
-  }
-
-  uintptr_t thread_addr = reinterpret_cast<uintptr_t>(thread);
-  DCHECK_EQ(RoundUp(thread_addr, kPageSize), thread_addr + GetProtectionOffset());
-  void* page_address = reinterpret_cast<void*>(RoundUp(thread_addr, kPageSize));
-  mprotect(page_address, kPageSize, PROT_READ);
-}
-
-static void UnprotectThread(Thread* thread) {
-  if (!kUseWriteProtectScheme) {
-    return;
-  }
-
-  uintptr_t thread_addr = reinterpret_cast<uintptr_t>(thread);
-  DCHECK_EQ(RoundUp(thread_addr, kPageSize), thread_addr + GetProtectionOffset());
-  void* page_address = reinterpret_cast<void*>(RoundUp(thread_addr, kPageSize));
-  mprotect(page_address, kPageSize, PROT_READ | PROT_WRITE);
-}
-
-void Thread::DeleteThread(Thread* thread) {
-  if (!kUseWriteProtectScheme) {
-    delete thread;
-    return;
-  }
-
-  if (thread == nullptr) {
-    return;
-  }
-
-  UnprotectThread(thread);
-  thread->~Thread();
-
-  // There should be the MemMap* at the bottom.
-  MemMap* mem_map =
-      *reinterpret_cast<MemMap**>(RoundDown(reinterpret_cast<uintptr_t>(thread), kPageSize));
-
-  delete mem_map;
-}
-
 void Thread::InitStringEntryPoints() {
-  // Ensure things are writable. This may be a late initialization of the entrypoints for the main
-  // thread.
-  UnprotectThread(this);
-
   ScopedObjectAccess soa(this);
   QuickEntryPoints* qpoints = &tlsPtr_.quick_entrypoints;
   qpoints->pNewEmptyString = reinterpret_cast<void(*)()>(
@@ -226,9 +141,6 @@ void Thread::InitStringEntryPoints() {
       soa.DecodeMethod(WellKnownClasses::java_lang_StringFactory_newStringFromStringBuffer));
   qpoints->pNewStringFromStringBuilder = reinterpret_cast<void(*)()>(
       soa.DecodeMethod(WellKnownClasses::java_lang_StringFactory_newStringFromStringBuilder));
-
-  // This is a good time to protect things, now that all entrypoints are set.
-  ProtectThread(this);
 }
 
 void Thread::ResetQuickAllocEntryPointsForThread() {
@@ -494,7 +406,7 @@ void Thread::CreateNativeThread(JNIEnv* env, jobject java_peer, size_t stack_siz
     return;
   }
 
-  Thread* child_thread = AllocateThread(is_daemon);
+  Thread* child_thread = new Thread(is_daemon);
   // Use global JNI ref to hold peer live while child thread starts.
   child_thread->tlsPtr_.jpeer = env->NewGlobalRef(java_peer);
   stack_size = FixStackSize(stack_size);
@@ -542,7 +454,7 @@ void Thread::CreateNativeThread(JNIEnv* env, jobject java_peer, size_t stack_siz
   // Manually delete the global reference since Thread::Init will not have been run.
   env->DeleteGlobalRef(child_thread->tlsPtr_.jpeer);
   child_thread->tlsPtr_.jpeer = nullptr;
-  DeleteThread(child_thread);
+  delete child_thread;
   child_thread = nullptr;
   // TODO: remove from thread group?
   env->SetLongField(java_peer, WellKnownClasses::java_lang_Thread_nativePeer, 0);
@@ -613,11 +525,11 @@ Thread* Thread::Attach(const char* thread_name, bool as_daemon, jobject thread_g
       return nullptr;
     } else {
       Runtime::Current()->StartThreadBirth();
-      self = AllocateThread(as_daemon);
+      self = new Thread(as_daemon);
       bool init_success = self->Init(runtime->GetThreadList(), runtime->GetJavaVM());
       Runtime::Current()->EndThreadBirth();
       if (!init_success) {
-        DeleteThread(self);
+        delete self;
         return nullptr;
       }
     }