Kernel: Demangle kernel C++ symbols correctly again

I broke this while implementing module linking. Also move the actual
demangling work to AK, in AK::demangle(const char*)

AK/Demangle.h

@@ -0,0 +1,21 @@
+#pragma once
+
+#include <AK/String.h>
+#include <cxxabi.h>
+
+namespace AK {
+
+inline String demangle(const char* name)
+{
+    int status = 0;
+    auto* demangled_name = abi::__cxa_demangle(name, nullptr, nullptr, &status);
+    auto string = String(status == 0 ? demangled_name : name);
+    if (status == 0)
+        kfree(demangled_name);
+    return string;
+}
+
+}
+
+using AK::demangle;
+

Kernel/KSyms.cpp

@@ -1,3 +1,4 @@
+#include <AK/Demangle.h>
 #include <AK/TemporaryChange.h>
 #include <Kernel/FileSystem/FileDescription.h>
 #include <Kernel/KSyms.h>
@@ -115,11 +116,6 @@ static void load_ksyms_from_data(const ByteBuffer& buffer)
         return;
     }
     ASSERT(recognized_symbol_count <= max_recognized_symbol_count);
-    size_t bytes_needed = 0;
-    for (int i = 0; i < recognized_symbol_count; ++i) {
-        auto& symbol = recognized_symbols[i];
-        bytes_needed += (symbol.ksym ? strlen(symbol.ksym->name) : 0) + 8 + 16;
-    }
     for (int i = 0; i < recognized_symbol_count; ++i) {
         auto& symbol = recognized_symbols[i];
         if (!symbol.address)
@@ -136,7 +132,7 @@ static void load_ksyms_from_data(const ByteBuffer& buffer)
         if (symbol.ksym->address == ksym_highest_address && offset > 4096)
             dbgprintf("%p\n", symbol.address);
         else
-            dbgprintf("%p  %s +%u\n", symbol.address, symbol.ksym->name, offset);
+            dbgprintf("%p  %s +%u\n", symbol.address, demangle(symbol.ksym->name).characters(), offset);
     }
 }
 

Kernel/Thread.cpp

@@ -1,3 +1,4 @@
+#include <AK/Demangle.h>
 #include <AK/StringBuilder.h>
 #include <Kernel/FileSystem/FileDescription.h>
 #include <Kernel/Process.h>
@@ -682,7 +683,7 @@ String Thread::backtrace_impl() const
         if (symbol.ksym->address == ksym_highest_address && offset > 4096)
             builder.appendf("%p\n", symbol.address);
         else
-            builder.appendf("%p  %s +%u\n", symbol.address, symbol.ksym->name, offset);
+            builder.appendf("%p  %s +%u\n", symbol.address, demangle(symbol.ksym->name).characters(), offset);
     }
     return builder.to_string();
 }

Libraries/LibELF/ELFLoader.cpp

@@ -1,7 +1,7 @@
 #include "ELFLoader.h"
+#include <AK/Demangle.h>
 #include <AK/QuickSort.h>
 #include <AK/kstdio.h>
-#include <cxxabi.h>
 
 #ifdef KERNEL
 #include <Kernel/VM/MemoryManager.h>
@@ -139,12 +139,7 @@ String ELFLoader::symbolicate(u32 address) const
             if (i == 0)
                 return "!!";
             auto& symbol = sorted_symbols[i - 1];
-            int status = 0;
-            auto* demangled_name = abi::__cxa_demangle(symbol.name, nullptr, nullptr, &status);
-            auto string = String::format("%s +%u", status == 0 ? demangled_name : symbol.name, address - symbol.address);
-            if (status == 0)
-                kfree(demangled_name);
-            return string;
+            return String::format("%s +%u", demangle(symbol.name).characters(), address - symbol.address);
         }
     }
     return "??";