[core] Unstub AliasRegionExtraSize

src/core/hle/kernel/k_page_table_base.h

@@ -715,6 +715,17 @@ public:
         return m_address_space_width;
     }
 
+    size_t CalculateAliasRegionExtraSize() const {
+        const size_t baseline = 64ull << 30;   // Mostly appropriate for DRAM values <= 8GB
+        const size_t region = GetAliasRegionSize();
+
+        if (region > baseline) {
+            return region - baseline;
+        }
+
+        return 0;
+    }
+
 public:
     // Linear mapped
     static u8* GetLinearMappedVirtualPointer(KernelCore& kernel, KPhysicalAddress addr) {

src/core/hle/kernel/k_process_page_table.h

@@ -410,6 +410,9 @@ public:
     size_t GetAliasRegionSize() const {
         return m_page_table.GetAliasRegionSize();
     }
+    size_t GetAliasRegionExtraSize() const {
+        return m_page_table.CalculateAliasRegionExtraSize();
+    }
     size_t GetStackRegionSize() const {
         return m_page_table.GetStackRegionSize();
     }

src/core/hle/kernel/svc/svc_info.cpp

@@ -61,7 +61,6 @@ Result GetInfo(Core::System& system, u64* result, InfoType info_id_type, Handle
         case InfoType::AliasRegionSize:
             *result = process->GetPageTable().GetAliasRegionSize();
             R_SUCCEED();
-
         case InfoType::HeapRegionAddress:
             *result = GetInteger(process->GetPageTable().GetHeapRegionStart());
             R_SUCCEED();
@@ -135,9 +134,16 @@ Result GetInfo(Core::System& system, u64* result, InfoType info_id_type, Handle
             }
             R_SUCCEED();
 
-        case InfoType::AliasRegionExtraSize:
-            // TODO (jarrodnorwell): do this when KIP's NPDM header is finished
+        case InfoType::AliasRegionExtraSize: {
+            if (info_sub_id != 0) {
+                return ResultInvalidCombination;
+            }
+
+            KProcess* current_process = GetCurrentProcessPointer(system.Kernel());
+            *result = current_process->GetPageTable().GetAliasRegionExtraSize();
+
             R_SUCCEED();
+        }
 
         default:
             break;