fix: plug memory map leak, save sp_el0, dynamic UART, kill loop

- Bootloader: reallocate memory map buffer when ExitBootServices fails,
  so GetMemoryMap doesn't scribble past the old allocation on retry.
- vectors.S: actually store sp_el0 into the exception frame. Previously
  it was read into x24 and then… vanished. EL0 tasks would wake up with
  a corrupted stack pointer. Not great.
- Serial: split hardcoded 0x09000000 into a fallback default; add
  SerialUpdate() so the DTB-parsed UART address actually gets used.
- DTB: add bounds check on reserved[] with PMM's 3 extra slots accounted
  for, so malformed/overstuffed DTBs don't silently corrupt memory.
- PMM.h: bump kVMMaxReservedRegions 128→256, define kPMMReservedRegionCount.
- Types.h: remove `#define loop while(1)`. while(true) is fine.
- Rename IOSerial* → Serial* — the IO prefix was redundant, Serial.c
  already lives under IO/.

Kernel/Source/Arch/DTB.c

@@ -24,10 +24,13 @@ void DTBParse(Pointer dtb, VMBootMemoryMap* bootMap) {
 
     ASCII* currentNode = "";
     UInt32 currentDepth = 0;
-    UInt32 reservedMemoryDepth = 0; 
+    UInt32 reservedMemoryDepth = 0;
     Boolean inReservedMemory = false;
 
     while (true) {
+        if (bootMap->reservedCount + kPMMReservedRegionCount >= kVMMaxReservedRegions) {
+            OSPanic("Too many reserved memory regions!"); // should never occur but jic
+        }
         UInt32 token = BytesSwap32(*(UInt32*)structs);
         structs += 4;
 
@@ -81,7 +84,7 @@ void DTBParse(Pointer dtb, VMBootMemoryMap* bootMap) {
 
                         bootMap->GIC.GICD.base = Merge32To64(BytesSwap32(cells[1]), BytesSwap32(cells[0]));
                         bootMap->GIC.GICD.size = Merge32To64(BytesSwap32(cells[3]), BytesSwap32(cells[2]));
-                        
+
                         bootMap->GIC.GICC.base = Merge32To64(BytesSwap32(cells[5]), BytesSwap32(cells[4]));
                         bootMap->GIC.GICC.size = Merge32To64(BytesSwap32(cells[7]), BytesSwap32(cells[6]));
                     }
@@ -99,7 +102,7 @@ void DTBParse(Pointer dtb, VMBootMemoryMap* bootMap) {
                 currentDepth--;
                 break;
             }
-            
+
             case FDTTokenNOP: continue;
             case FDTTokenEnd: return;
             default:
@@ -107,4 +110,4 @@ void DTBParse(Pointer dtb, VMBootMemoryMap* bootMap) {
         }
     }
 
-}
+}

Kernel/Source/Arch/vectors.S

@@ -1,7 +1,7 @@
 .macro ventry type
     .align 7
     sub sp, sp, #288 // save 288 bytes of stack
-    stp x0, x1, [sp, #0] // move stack 
+    stp x0, x1, [sp, #0] // move stack
     mov x1, #\type // move type to x1
     b ExceptionsTrapEntry
 .endm
@@ -54,6 +54,7 @@ ExceptionsTrapEntry:
 
     stp x30, x21, [sp, #16 * 15]
     stp x22, x23, [sp, #16 * 16]
+    stp x24, xzr, [sp, #16 * 17]
 
     mov x0, sp
     bl ExceptionsHandler
@@ -92,4 +93,4 @@ ExceptionsVectorsInit:
     adr x0, ExceptionsVectorsTable
     msr vbar_el1, x0
     isb
-    ret
+    ret