fix: fix hot loader page reuse for overlapping init segments

System/inc/VM/VMM.h

@@ -37,6 +37,7 @@
 
 void VMVirtualMemoryInitialize(Bootinfo* info);
 UInt64* VMVirtualMemoryMapPage(UInt64* PML4, UInt64 physical, UInt64 virtual, UInt64 flags);
+void* VMVirtualMemoryGetOrAllocatePage(UInt64* PML4, UInt64 virtual, UInt64 flags);
 UInt64 VMVirtualMemoryCreateAddressSpace();
 UInt64 VMGetCurrentCR3();
 void VMLoadCR3(UInt64 PML4Address);

System/src/OS/Exec/HOTLoader.c

@@ -26,10 +26,10 @@ UInt64 HOTLoad(OSProcess* process, UInt8* data) {
         UInt64 end = (segment->vaddr + segment->memsz + 0xFFF) & ~(0xFFFULL);
 
         for (UInt64 address = start; address < end; address += kVMPageSize) {
-            void* physicalPage = VMPhysicalMemoryAllocatePage();
+            void* kernelVirtAddress = VMVirtualMemoryGetOrAllocatePage((UInt64*)process->physicalPML4, address, PTE_USER | PTE_RW | PTE_PRESENT);
-            VMVirtualMemoryMapPage((UInt64*)process->physicalPML4, (UInt64)physicalPage, address, PTE_USER | PTE_RW | PTE_PRESENT);
+            if (!kernelVirtAddress) {
-            void* kernelVirtAddress = (void*)((UInt64)physicalPage + HHDM_OFFSET);
+                return 0;
-            MemorySet(kernelVirtAddress, 0, kVMPageSize);
+            }
             UInt64 pageOverleapStart = (address > segment->vaddr) ? address : segment->vaddr;
             UInt64 pageOverleapEnd = (address + kVMPageSize < segment->vaddr + segment->filesz) 
                 ? (address + kVMPageSize) 

System/src/VM/VMM.c

@@ -94,6 +94,28 @@ static UInt64* sVMVirtualMemoryMapPageInternal(UInt64* pml4, UInt64 phys, UInt64
     return (UInt64*)virt;
 }
 
+static void* sVMVirtualMemoryGetMappedPageInternal(UInt64* pml4, UInt64 virt) {
+    UInt64 pt_idx = VMM_PT_INDEX(virt);
+    UInt64 pd_idx = VMM_PD_INDEX(virt);
+    UInt64 pdpt_idx = VMM_PDPT_INDEX(virt);
+    UInt64 pml4_idx = VMM_PML4_INDEX(virt);
+
+    UInt64* pml4_virt = pml4;
+    if (isInitialized) pml4_virt = (UInt64*)PHYS_TO_HHDM((UInt64)pml4);
+
+    if (!(pml4_virt[pml4_idx] & PTE_PRESENT)) return nullptr;
+    UInt64* pdpt_virt = sVMGetVirtualTable(PTE_GET_ADDR(pml4_virt[pml4_idx]));
+
+    if (!(pdpt_virt[pdpt_idx] & PTE_PRESENT)) return nullptr;
+    UInt64* pd_virt = sVMGetVirtualTable(PTE_GET_ADDR(pdpt_virt[pdpt_idx]));
+
+    if (!(pd_virt[pd_idx] & PTE_PRESENT)) return nullptr;
+    UInt64* pt_virt = sVMGetVirtualTable(PTE_GET_ADDR(pd_virt[pd_idx]));
+
+    if (!(pt_virt[pt_idx] & PTE_PRESENT)) return nullptr;
+    return (void*)PHYS_TO_HHDM(PTE_GET_ADDR(pt_virt[pt_idx]));
+}
+
 static void sVMVirtualMemoryUnmapPageInternal(UInt64* pml4, UInt64 virt) {
     UInt64 pt_idx = VMM_PT_INDEX(virt);
     UInt64 pd_idx = VMM_PD_INDEX(virt);
@@ -128,6 +150,35 @@ UInt64* VMVirtualMemoryMapPage(UInt64* pml4, UInt64 phys, UInt64 virt, UInt64 fl
     return result;
 }
 
+void* VMVirtualMemoryGetOrAllocatePage(UInt64* pml4, UInt64 virt, UInt64 flags) {
+    OSSpinlockState state;
+    OSSpinlockLockIRQ(&sVMVMMlock, &state);
+
+    void* mappedPage = sVMVirtualMemoryGetMappedPageInternal(pml4, virt);
+    if (mappedPage) {
+        OSSpinlockUnlockIRQ(&sVMVMMlock, &state);
+        return mappedPage;
+    }
+
+    void* physicalPage = VMPhysicalMemoryAllocatePage();
+    if (!physicalPage) {
+        OSSpinlockUnlockIRQ(&sVMVMMlock, &state);
+        return nullptr;
+    }
+
+    UInt64* result = sVMVirtualMemoryMapPageInternal(pml4, (UInt64)physicalPage, virt, flags);
+    if (!result) {
+        OSSpinlockUnlockIRQ(&sVMVMMlock, &state);
+        return nullptr;
+    }
+
+    void* kernelVirtualAddress = (void*)PHYS_TO_HHDM((UInt64)physicalPage);
+    MemorySet(kernelVirtualAddress, 0, kVMPageSize);
+
+    OSSpinlockUnlockIRQ(&sVMVMMlock, &state);
+    return kernelVirtualAddress;
+}
+
 void VMVirtualMemoryUnmapPage(UInt64* pml4, UInt64 virt) {
     OSSpinlockState state;
     OSSpinlockLockIRQ(&sVMVMMlock, &state);