Reserve a page at the beginning of the code range on Win64 for SEH

src/heap/spaces.cc

 // Copyright 2011 the V8 project 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 "src/v8.h"
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/full-codegen.h"
 #include "src/heap/mark-compact.h"
@@ skipping 92 matching lines @@
     // When a target requires the code range feature, we put all code objects
     // in a kMaximalCodeRangeSize range of virtual address space, so that
     // they can call each other with near calls.
     if (kRequiresCodeRange) {
       requested = kMaximalCodeRangeSize;
     } else {
       return true;
     }
   }
 
+  if (requested < kMinimumCodeRangeSize) {
+    requested = kMinimumCodeRangeSize;
+  }
+
   DCHECK(!kRequiresCodeRange || requested <= kMaximalCodeRangeSize);
   code_range_ = new base::VirtualMemory(requested);
   CHECK(code_range_ != NULL);
   if (!code_range_->IsReserved()) {
     delete code_range_;
     code_range_ = NULL;
     return false;
   }
 
   // We are sure that we have mapped a block of requested addresses.
   DCHECK(code_range_->size() == requested);
-  LOG(isolate_, NewEvent("CodeRange", code_range_->address(), requested));
   Address base = reinterpret_cast<Address>(code_range_->address());
-  Address aligned_base =
-      RoundUp(reinterpret_cast<Address>(code_range_->address()),
-              MemoryChunk::kAlignment);
+
+  // On some platforms, specifically Win64, we need to reserve some pages at
+  // the beginning of an executable space.
+  if (kReservedCodeRangePages) {
+    if (!code_range_->Commit(
+            base, kReservedCodeRangePages * base::OS::CommitPageSize(), true)) {
+      delete code_range_;
+      code_range_ = NULL;
+      return false;
+    }
+    base += kReservedCodeRangePages * base::OS::CommitPageSize();
+  }
+  Address aligned_base = RoundUp(base, MemoryChunk::kAlignment);
   size_t size = code_range_->size() - (aligned_base - base);
   allocation_list_.Add(FreeBlock(aligned_base, size));
   current_allocation_block_index_ = 0;
+
+  LOG(isolate_, NewEvent("CodeRange", code_range_->address(), requested));
   return true;
 }
 
 
 int CodeRange::CompareFreeBlockAddress(const FreeBlock* left,
                                        const FreeBlock* right) {
   // The entire point of CodeRange is that the difference between two
   // addresses in the range can be represented as a signed 32-bit int,
   // so the cast is semantically correct.
   return static_cast<int>(left->start - right->start);
@@ skipping 2954 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }
 }  // namespace v8::internal