--- a/hotspot/src/share/vm/prims/jvmtiEnvBase.cpp	Mon Mar 02 14:03:03 2009 -0700
+++ b/hotspot/src/share/vm/prims/jvmtiEnvBase.cpp	Mon Mar 02 14:05:07 2009 -0700
@@ -94,6 +94,35 @@
 }
 
 
+bool
+JvmtiEnvBase::is_valid() {
+  jint value = 0;
+
+  // This object might not be a JvmtiEnvBase so we can't assume
+  // the _magic field is properly aligned. Get the value in a safe
+  // way and then check against JVMTI_MAGIC.
+
+  switch (sizeof(_magic)) {
+  case 2:
+    value = Bytes::get_native_u2((address)&_magic);
+    break;
+
+  case 4:
+    value = Bytes::get_native_u4((address)&_magic);
+    break;
+
+  case 8:
+    value = Bytes::get_native_u8((address)&_magic);
+    break;
+
+  default:
+    guarantee(false, "_magic field is an unexpected size");
+  }
+
+  return value == JVMTI_MAGIC;
+}
+
+
 JvmtiEnvBase::JvmtiEnvBase() : _env_event_enable() {
   _env_local_storage = NULL;
   _tag_map = NULL;

--- a/hotspot/src/share/vm/prims/jvmtiEnvBase.hpp	Mon Mar 02 14:03:03 2009 -0700
+++ b/hotspot/src/share/vm/prims/jvmtiEnvBase.hpp	Mon Mar 02 14:05:07 2009 -0700
@@ -120,7 +120,7 @@
 
  public:
 
-  bool is_valid()                                  { return _magic == JVMTI_MAGIC; }
+  bool is_valid();
 
   bool is_retransformable()                        { return _is_retransformable; }
 

--- a/hotspot/src/share/vm/prims/jvmtiImpl.cpp	Mon Mar 02 14:03:03 2009 -0700
+++ b/hotspot/src/share/vm/prims/jvmtiImpl.cpp	Mon Mar 02 14:05:07 2009 -0700
@@ -238,6 +238,35 @@
 }
 
 
+bool
+JvmtiRawMonitor::is_valid() {
+  int value = 0;
+
+  // This object might not be a JvmtiRawMonitor so we can't assume
+  // the _magic field is properly aligned. Get the value in a safe
+  // way and then check against JVMTI_RM_MAGIC.
+
+  switch (sizeof(_magic)) {
+  case 2:
+    value = Bytes::get_native_u2((address)&_magic);
+    break;
+
+  case 4:
+    value = Bytes::get_native_u4((address)&_magic);
+    break;
+
+  case 8:
+    value = Bytes::get_native_u8((address)&_magic);
+    break;
+
+  default:
+    guarantee(false, "_magic field is an unexpected size");
+  }
+
+  return value == JVMTI_RM_MAGIC;
+}
+
+
 //
 // class JvmtiBreakpoint
 //

--- a/hotspot/src/share/vm/prims/jvmtiImpl.hpp	Mon Mar 02 14:03:03 2009 -0700
+++ b/hotspot/src/share/vm/prims/jvmtiImpl.hpp	Mon Mar 02 14:05:07 2009 -0700
@@ -349,7 +349,7 @@
   ~JvmtiRawMonitor();
   int            magic()   { return _magic;  }
   const char *get_name()   { return _name; }
-  bool        is_valid()   { return _magic == JVMTI_RM_MAGIC;  }
+  bool        is_valid();
 };
 
 // Onload pending raw monitors