[heap] Reland register executable MemoryChunks.

Bug: chromium:774108,v8:6792
Change-Id: I4736b86ad5bd5e0777dc7a121023c4ed34d69fb0
Reviewed-on: https://chromium-review.googlesource.com/873170
Commit-Queue: Hannes Payer <hpayer@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50683}

src/heap/heap-inl.h

@@ -626,6 +626,7 @@ CodeSpaceMemoryModificationScope::CodeSpaceMemoryModificationScope(Heap* heap)
     LargePage* page = heap_->lo_space()->first_page();
     while (page != nullptr) {
       if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
+        CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
         page->SetReadAndWritable();
       }
       page = page->next_page();
@@ -640,6 +641,7 @@ CodeSpaceMemoryModificationScope::~CodeSpaceMemoryModificationScope() {
     LargePage* page = heap_->lo_space()->first_page();
     while (page != nullptr) {
       if (page->IsFlagSet(MemoryChunk::IS_EXECUTABLE)) {
+        CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
         page->SetReadAndExecutable();
       }
       page = page->next_page();

src/heap/heap.h

@@ -2658,6 +2658,7 @@ class AlwaysAllocateScope {
   Heap* heap_;
 };
 
+// The CodeSpaceMemoryModificationScope can only be used by the main thread.
 class CodeSpaceMemoryModificationScope {
  public:
   explicit inline CodeSpaceMemoryModificationScope(Heap* heap);
@@ -2667,6 +2668,9 @@ class CodeSpaceMemoryModificationScope {
   Heap* heap_;
 };
 
+// The CodePageMemoryModificationScope does not check if tansitions to
+// writeable and back to executable are actually allowed, i.e. the MemoryChunk
+// was registered to be executable. It can be used by concurrent threads.
 class CodePageMemoryModificationScope {
  public:
   explicit inline CodePageMemoryModificationScope(MemoryChunk* chunk);

src/heap/spaces.cc

@@ -826,8 +826,13 @@ MemoryChunk* MemoryAllocator::AllocateChunk(size_t reserve_area_size,
                          owner);
   }
 
-  return MemoryChunk::Initialize(heap, base, chunk_size, area_start, area_end,
-                                 executable, owner, &reservation);
+  MemoryChunk* chunk =
+      MemoryChunk::Initialize(heap, base, chunk_size, area_start, area_end,
+                              executable, owner, &reservation);
+
+  if (chunk->executable()) RegisterExecutableMemoryChunk(chunk);
+
+  return chunk;
 }
 
 void Page::ResetAllocatedBytes() { allocated_bytes_ = area_size(); }
@@ -970,6 +975,8 @@ void MemoryAllocator::PreFreeMemory(MemoryChunk* chunk) {
   }
 
   chunk->SetFlag(MemoryChunk::PRE_FREED);
+
+  if (chunk->executable()) UnregisterExecutableMemoryChunk(chunk);
 }
 
 
@@ -1722,6 +1729,7 @@ void PagedSpace::ReleasePage(Page* page) {
 void PagedSpace::SetReadAndExecutable() {
   DCHECK(identity() == CODE_SPACE);
   for (Page* page : *this) {
+    CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
     page->SetReadAndExecutable();
   }
 }
@@ -1729,6 +1737,7 @@ void PagedSpace::SetReadAndExecutable() {
 void PagedSpace::SetReadAndWritable() {
   DCHECK(identity() == CODE_SPACE);
   for (Page* page : *this) {
+    CHECK(heap_->memory_allocator()->IsMemoryChunkExecutable(page));
     page->SetReadAndWritable();
   }
 }

src/heap/spaces.h

@@ -1359,6 +1359,12 @@ class V8_EXPORT_PRIVATE MemoryAllocator {
   // and false otherwise.
   bool CommitBlock(Address start, size_t size, Executability executable);
 
+  // Checks if an allocated MemoryChunk was intended to be used for executable
+  // memory.
+  bool IsMemoryChunkExecutable(MemoryChunk* chunk) {
+    return executable_memory_.find(chunk) != executable_memory_.end();
+  }
+
   // Uncommit a contiguous block of memory [start..(start+size)[.
   // start is not nullptr, the size is greater than zero, and the
   // block is contained in the initial chunk.  Returns true if it succeeded
@@ -1409,6 +1415,17 @@ class V8_EXPORT_PRIVATE MemoryAllocator {
     } while ((high > ptr) && !highest_ever_allocated_.TrySetValue(ptr, high));
   }
 
+  void RegisterExecutableMemoryChunk(MemoryChunk* chunk) {
+    DCHECK(chunk->IsFlagSet(MemoryChunk::IS_EXECUTABLE));
+    DCHECK_EQ(executable_memory_.find(chunk), executable_memory_.end());
+    executable_memory_.insert(chunk);
+  }
+
+  void UnregisterExecutableMemoryChunk(MemoryChunk* chunk) {
+    DCHECK_NE(executable_memory_.find(chunk), executable_memory_.end());
+    executable_memory_.erase(chunk);
+  }
+
   Isolate* isolate_;
   CodeRange* code_range_;
 
@@ -1431,6 +1448,9 @@ class V8_EXPORT_PRIVATE MemoryAllocator {
   VirtualMemory last_chunk_;
   Unmapper unmapper_;
 
+  // Data structure to remember allocated executable memory chunks.
+  std::unordered_set<MemoryChunk*> executable_memory_;
+
   friend class heap::TestCodeRangeScope;
 
   DISALLOW_IMPLICIT_CONSTRUCTORS(MemoryAllocator);