Add basic infrastructure for protecting V8's heap when leaving the VM...

src/platform-linux.cc

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 220 matching lines @@
 }
 
 
 size_t OS::AllocateAlignment() {
   return sysconf(_SC_PAGESIZE);
 }
 
 
 void* OS::Allocate(const size_t requested,
                    size_t* allocated,
-                   bool executable) {
+                   bool is_executable) {
   const size_t msize = RoundUp(requested, sysconf(_SC_PAGESIZE));
-  int prot = PROT_READ | PROT_WRITE | (executable ? PROT_EXEC : 0);
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
   void* mbase = mmap(NULL, msize, prot, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
   if (mbase == MAP_FAILED) {
     LOG(StringEvent("OS::Allocate", "mmap failed"));
     return NULL;
   }
   *allocated = msize;
   UpdateAllocatedSpaceLimits(mbase, msize);
   return mbase;
 }
 
 
-void OS::Free(void* buf, const size_t length) {
+void OS::Free(void* address, const size_t size) {
   // TODO(1240712): munmap has a return value which is ignored here.

[Søren Thygesen Gjesse, 2009/03/24 11:43:55]

Move this issue to code.google.com/p/v8.

-  munmap(buf, length);
+  munmap(address, size);
 }
 
 
+#ifdef ENABLE_HEAP_PROTECTION
+
+void OS::Protect(void* address, size_t size) {
+  // TODO(1240712): mprotect has a return value which is ignored here.
+  mprotect(address, size, PROT_READ);
+}
+
+
+void OS::Unprotect(void* address, size_t size, bool is_executable) {
+  // TODO(1240712): mprotect has a return value which is ignored here.
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
+  mprotect(address, size, prot);
+}
+
+#endif
+
+
 void OS::Sleep(int milliseconds) {
   unsigned int ms = static_cast<unsigned int>(milliseconds);
   usleep(1000 * ms);
 }
 
 
 void OS::Abort() {
   // Redirect to std abort to signal abnormal program termination.
   abort();
 }
 
 
 void OS::DebugBreak() {
-#if defined (__arm__) || defined(__thumb__)
+#ifdef ARM
   asm("bkpt 0");
 #else
   asm("int $3");
 #endif
 }
 
 
 class PosixMemoryMappedFile : public OS::MemoryMappedFile {
  public:
   PosixMemoryMappedFile(FILE* file, void* memory, int size)
@@ skipping 130 matching lines @@
     if (0 == munmap(address(), size())) address_ = MAP_FAILED;
   }
 }
 
 
 bool VirtualMemory::IsReserved() {
   return address_ != MAP_FAILED;
 }
 
 
-bool VirtualMemory::Commit(void* address, size_t size, bool executable) {
-  int prot = PROT_READ | PROT_WRITE | (executable ? PROT_EXEC : 0);
+bool VirtualMemory::Commit(void* address, size_t size, bool is_executable) {
+  int prot = PROT_READ | PROT_WRITE | (is_executable ? PROT_EXEC : 0);
   if (MAP_FAILED == mmap(address, size, prot,
                          MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
                          kMmapFd, kMmapFdOffset)) {
     return false;
   }
 
   UpdateAllocatedSpaceLimits(address, size);
   return true;
 }
 
@@ skipping 475 matching lines @@
   }
 
   // This sampler is no longer the active sampler.
   active_sampler_ = NULL;
   active_ = false;
 }
 
 #endif  // ENABLE_LOGGING_AND_PROFILING
 
 } }  // namespace v8::internal