Kernel: Note if the page fault address is a destroyed smart pointer

While I was working on LibWeb, I got a page fault at 0xe0e0e0e4.
This indicates a destroyed RefPtr if compiled with SANITIZE_PTRS
defined. However, the page fault handler didn't print out this
indication.

This makes the page fault handler print out a note if the faulting
address looks like a recently destroyed RefPtr, OwnPtr, NonnullRefPtr,
NonnullOwnPtr, ThreadSafeRefPtr or ThreadSafeNonnullRefPtr. It will
only do this if SANITIZE_PTRS is defined, as smart pointers don't get
scrubbed without it being defined.

AK/NonnullOwnPtr.h

@@ -13,6 +13,8 @@
 #include <AK/Traits.h>
 #include <AK/Types.h>
 
+#define NONNULLOWNPTR_SCRUB_BYTE 0xf1
+
 namespace AK {
 
 template<typename T, typename PtrTraits>
@@ -51,7 +53,7 @@ public:
     {
         clear();
 #ifdef SANITIZE_PTRS
-        m_ptr = (T*)(explode_byte(0xe3));
+        m_ptr = (T*)(explode_byte(NONNULLOWNPTR_SCRUB_BYTE));
 #endif
     }
 

AK/NonnullRefPtr.h

@@ -6,6 +6,8 @@
 
 #pragma once
 
+#define NONNULLREFPTR_SCRUB_BYTE 0xe1
+
 #ifdef KERNEL
 #    include <Kernel/Library/ThreadSafeNonnullRefPtr.h>
 #else
@@ -97,7 +99,7 @@ public:
         unref_if_not_null(m_ptr);
         m_ptr = nullptr;
 #    ifdef SANITIZE_PTRS
-        m_ptr = reinterpret_cast<T*>(explode_byte(0xb0));
+        m_ptr = reinterpret_cast<T*>(explode_byte(NONNULLREFPTR_SCRUB_BYTE));
 #    endif
     }
 

AK/OwnPtr.h

@@ -12,6 +12,8 @@
 #    include <Kernel/API/KResult.h>
 #endif
 
+#define OWNPTR_SCRUB_BYTE 0xf0
+
 namespace AK {
 
 template<typename T>
@@ -43,7 +45,7 @@ public:
     {
         clear();
 #ifdef SANITIZE_PTRS
-        m_ptr = (T*)(explode_byte(0xe1));
+        m_ptr = (T*)(explode_byte(OWNPTR_SCRUB_BYTE));
 #endif
     }
 

AK/RefPtr.h

@@ -6,6 +6,8 @@
 
 #pragma once
 
+#define REFPTR_SCRUB_BYTE 0xe0
+
 #ifdef KERNEL
 #    include <Kernel/Library/ThreadSafeRefPtr.h>
 #else
@@ -100,7 +102,7 @@ public:
     {
         clear();
 #    ifdef SANITIZE_PTRS
-        m_ptr = reinterpret_cast<T*>(explode_byte(0xe0));
+        m_ptr = reinterpret_cast<T*>(explode_byte(REFPTR_SCRUB_BYTE));
 #    endif
     }