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

Kernel/Source/IO/Serial.c

@@ -2,22 +2,28 @@
 #include <Arch/IO.h>
 #include <Arch/CPU.h>
 
-Int32 IOSerialPutCharacter(ASCII character) {
+static UInt64 sUARTAddress = kUARTBaseAddress;
+
+void SerialUpdate(UInt64 address) {
+    sUARTAddress = address;
+}
+
+Int32 SerialPutCharacter(ASCII character) {
     // TXFF -- TRansmit FIFO Full for PL011 is 5 bit of FR reg (0x18)
-    UInt64 uartFR = kUARTBaseAddress + 0x18;
+    UInt64 uartFR = sUARTAddress + 0x18;
 
     while ((IOAddressRead32(uartFR) & (1 << 5)) != 0)  {
         CPUYield();
     }
 
-    IOAddressWrite32(kUARTBaseAddress, character);
+    IOAddressWrite32(sUARTAddress, character);
     return character;
 }
 
-Int32 IOSerialPutString(const ASCII* string) {
+Int32 SerialPutString(const ASCII* string) {
     Int i = 0;
     while (string[i] != '\0') {
-        IOSerialPutCharacter(string[i]);
+        SerialPutCharacter(string[i]);
         i++;
     }
 

Kernel/Source/KernelMain.c

@@ -3,6 +3,7 @@
 #include <Arch/Timer.h>
 #include <Arch/CPU.h>
 #include <Arch/GIC.h>
+#include <IO/Serial.h>
 #include <VM/PMM.h>
 #include <VM/VMM.h>
 #include <VM/Heap.h>
@@ -17,9 +18,10 @@ void KernelMain(Bootinfo* bootinfo) {
     }
 
     VMBootMemoryMap bootMap = {0};
-    
+
     bootMap.reservedCount = 0;
     DTBParse(bootinfo->dtb, &bootMap);
+    SerialUpdate(bootMap.UART.base);
 
     PMMInitialize(&bootMap);
     VMMInitialize(&bootMap, bootinfo);

Kernel/Source/OS/Log.c

@@ -5,11 +5,11 @@
 
 void OSLog(const ASCII* format, ...) {
     ASCII buffer[kOSLogBufferSize];
-   
+
     va_list args;
     va_start(args, format);
     StringFormatVariadic(buffer, kOSLogBufferSize, format, args);
     va_end(args);
 
-    IOSerialPutString(buffer);
-}
+    SerialPutString(buffer);
+}

Kernel/Source/OS/Panic.c

@@ -40,7 +40,7 @@ static const ASCII* sFunMessages[] = {
 };
 
 __attribute__((noreturn)) static void Halt() {
-    loop {
+    while (true) {
         CPUDisableInterrupts();
         CPUWaitForInterrupt();
     }
@@ -134,4 +134,4 @@ __attribute__((noreturn)) void OSPanicException(ExceptionsContext* frame) {
 
     DrawPanicFooter();
     Halt();
-}
+}

Kernel/Source/OS/Scheduler.c

@@ -85,11 +85,11 @@ Address SchedulerNext(Address stackPointer) {
         if (taskIterator->sleepTicks > 0) taskIterator->sleepTicks--;
         taskIterator = taskIterator->next;
     } while (taskIterator != gOSSchedulerCurrentTask->next);
-    
+
     if (gOSSchedulerCurrentTask->sleepTicks > 0) gOSSchedulerCurrentTask->sleepTicks--;
 
     OSTask* nextTask = gOSSchedulerCurrentTask->next;
-    loop {
+    while (true) {
         if (nextTask->state == OSTaskStateDead) {
             nextTask = nextTask->next;
             if (nextTask == gOSSchedulerCurrentTask) OSPanic("No running tasks");
@@ -110,7 +110,7 @@ Address SchedulerNext(Address stackPointer) {
         CPUSwitchAddressSpace(physicalL0Table);
     }
     gOSSchedulerCurrentTask = nextTask;
-    
+
     return gOSSchedulerCurrentTask->stackPointer;
 }
 
@@ -118,4 +118,4 @@ void SchedulerYield(UInt64 ticks) {
     gOSSchedulerCurrentTask->sleepTicks = ticks;
     gOSSchedulerCurrentTask->state = OSTaskStateSleeping;
     CPUException(kOSSchedulerExceptionNumber);
-}
+}