From 69a9f7f06a53a9211038610de9b0d3c900f6a65d Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Wed, 12 Oct 2022 20:02:25 +0200
Subject: [PATCH] Kernel: Move VMM from a class to a namespace

Also, rename the ugly Paging::VirtualMemoryManager name to just 'VMM'. Which is now used instead of kernelVMM.
---
 kernel/include/memory/Paging.h      |  39 +--
 kernel/include/memory/VMM.h         |  38 +-
 kernel/src/memory/MemoryManager.cpp |  26 +-
 kernel/src/memory/Paging.cpp        |   2 +-
 kernel/src/memory/VMM.cpp           | 519 ++++++++++++++--------------
 kernel/src/sys/exec.cpp             |   2 +-
 kernel/src/sys/mem.cpp              |   4 +-
 7 files changed, 308 insertions(+), 322 deletions(-)

diff --git a/kernel/include/memory/Paging.h b/kernel/include/memory/Paging.h
index 80bbbab5..9206f395 100644
--- a/kernel/include/memory/Paging.h
+++ b/kernel/include/memory/Paging.h
@@ -5,27 +5,24 @@
 #define PAGE_SIZE 4096
 #endif
 
-namespace Paging
+struct PageDirectoryEntry
 {
-    struct PageDirectoryEntry
-    {
-        bool Present : 1;
-        bool ReadWrite : 1;
-        bool UserSuper : 1;
-        bool WriteThrough : 1;
-        bool CacheDisabled : 1;
-        bool Accessed : 1;
-        bool ignore0 : 1;
-        bool LargerPages : 1;
-        bool ignore1 : 1;
-        uint8_t Available : 3;
-        uint64_t Address : 52;
+    bool Present : 1;
+    bool ReadWrite : 1;
+    bool UserSuper : 1;
+    bool WriteThrough : 1;
+    bool CacheDisabled : 1;
+    bool Accessed : 1;
+    bool ignore0 : 1;
+    bool LargerPages : 1;
+    bool ignore1 : 1;
+    uint8_t Available : 3;
+    uint64_t Address : 52;
 
-        void set_address(uint64_t addr);
-    };
+    void set_address(uint64_t addr);
+};
 
-    struct PageTable
-    {
-        PageDirectoryEntry entries[512];
-    } __attribute__((aligned(PAGE_SIZE)));
-}
\ No newline at end of file
+struct PageTable
+{
+    PageDirectoryEntry entries[512];
+} __attribute__((aligned(PAGE_SIZE)));
\ No newline at end of file
diff --git a/kernel/include/memory/VMM.h b/kernel/include/memory/VMM.h
index ce12e765..bca59d0b 100644
--- a/kernel/include/memory/VMM.h
+++ b/kernel/include/memory/VMM.h
@@ -1,29 +1,21 @@
 #pragma once
 #include "memory/Paging.h"
 
-namespace Paging
+enum Flags
 {
-    enum Flags
-    {
-        ReadWrite = 1 << 0,
-        User = 1 << 1,
-        Execute = 1 << 2
-    };
-    class VirtualMemoryManager
-    {
-      public:
-        void init(); // fetch page table from cr3
-        void init(PageTable* cr3);
+    ReadWrite = 1 << 0,
+    User = 1 << 1,
+    Execute = 1 << 2
+};
+namespace VMM
+{
+    void init(); // fetch page table from cr3
+    void init(PageTable* cr3);
 
-        void map(uint64_t virtualAddress, uint64_t physicalAddress, int flags);
-        void remap(uint64_t virtualAddress, int flags);
-        void unmap(uint64_t virtualAddress);
-        uint64_t getPhysical(uint64_t virtualAddress);
-        uint64_t getFlags(uint64_t virtualAddress);
+    void map(uint64_t virtualAddress, uint64_t physicalAddress, int flags);
+    void remap(uint64_t virtualAddress, int flags);
+    void unmap(uint64_t virtualAddress);
+    uint64_t getPhysical(uint64_t virtualAddress);
+    uint64_t getFlags(uint64_t virtualAddress);
 
-      private:
-        PageTable* PML4;
-    };
-}
-
-extern Paging::VirtualMemoryManager kernelVMM;
\ No newline at end of file
+};
\ No newline at end of file
diff --git a/kernel/src/memory/MemoryManager.cpp b/kernel/src/memory/MemoryManager.cpp
index e775ad5d..4a0a4390 100644
--- a/kernel/src/memory/MemoryManager.cpp
+++ b/kernel/src/memory/MemoryManager.cpp
@@ -12,7 +12,7 @@
 void MemoryManager::init()
 {
     PMM::init();
-    kernelVMM.init();
+    VMM::init();
     PMM::map_bitmap_to_virtual();
 }
 
@@ -26,7 +26,7 @@ void* MemoryManager::get_mapping(void* physicalAddress, int flags)
 #endif
         return 0;
     }
-    kernelVMM.map(virtualAddress, (uint64_t)physicalAddress, flags);
+    VMM::map(virtualAddress, (uint64_t)physicalAddress, flags);
     return (void*)virtualAddress;
 }
 
@@ -41,7 +41,7 @@ void* MemoryManager::get_unaligned_mapping(void* physicalAddress, int flags)
 #endif
         return 0;
     }
-    kernelVMM.map(virtualAddress, (uint64_t)physicalAddress - offset, flags);
+    VMM::map(virtualAddress, (uint64_t)physicalAddress - offset, flags);
     return (void*)(virtualAddress + offset);
 }
 
@@ -62,7 +62,7 @@ void* MemoryManager::get_unaligned_mappings(void* physicalAddress, uint64_t coun
     }
     for (uint64_t i = 0; i < count; i++)
     {
-        kernelVMM.map(virtualAddress + (i * PAGE_SIZE), ((uint64_t)physicalAddress - offset) + (i * PAGE_SIZE), flags);
+        VMM::map(virtualAddress + (i * PAGE_SIZE), ((uint64_t)physicalAddress - offset) + (i * PAGE_SIZE), flags);
     }
     return (void*)(virtualAddress + offset);
 }
@@ -70,7 +70,7 @@ void* MemoryManager::get_unaligned_mappings(void* physicalAddress, uint64_t coun
 void MemoryManager::release_unaligned_mapping(void* mapping)
 {
     uint64_t offset = (uint64_t)mapping % PAGE_SIZE;
-    kernelVMM.unmap((uint64_t)mapping - offset);
+    VMM::unmap((uint64_t)mapping - offset);
     KernelHeap::free_virtual_page((uint64_t)mapping - offset);
 }
 
@@ -80,12 +80,12 @@ void MemoryManager::release_unaligned_mappings(void* mapping, uint64_t count)
     if (count == 1) return release_unaligned_mapping(mapping);
     uint64_t offset = (uint64_t)mapping % PAGE_SIZE;
     KernelHeap::free_virtual_pages((uint64_t)mapping - offset, count);
-    for (uint64_t i = 0; i < count; i++) { kernelVMM.unmap(((uint64_t)mapping - offset) + (i * PAGE_SIZE)); }
+    for (uint64_t i = 0; i < count; i++) { VMM::unmap(((uint64_t)mapping - offset) + (i * PAGE_SIZE)); }
 }
 
 void MemoryManager::release_mapping(void* mapping)
 {
-    kernelVMM.unmap((uint64_t)mapping);
+    VMM::unmap((uint64_t)mapping);
     KernelHeap::free_virtual_page((uint64_t)mapping);
 }
 
@@ -112,15 +112,15 @@ void* MemoryManager::get_page_at(uint64_t addr, int flags)
 #endif
         return 0;
     }
-    kernelVMM.map(addr, (uint64_t)physicalAddress, flags);
+    VMM::map(addr, (uint64_t)physicalAddress, flags);
     return (void*)addr;
 }
 
 void MemoryManager::release_page(void* page)
 {
-    uint64_t physicalAddress = kernelVMM.getPhysical((uint64_t)page);
+    uint64_t physicalAddress = VMM::getPhysical((uint64_t)page);
     ASSERT(physicalAddress != UINT64_MAX); // this address is not mapped in the virtual address space...
-    kernelVMM.unmap((uint64_t)page);
+    VMM::unmap((uint64_t)page);
     PMM::free_page((void*)physicalAddress);
 }
 
@@ -162,7 +162,7 @@ void* MemoryManager::get_pages_at(uint64_t addr, uint64_t count, int flags)
 #endif
             return 0;
         }
-        kernelVMM.map(addr + (i * PAGE_SIZE), (uint64_t)physicalAddress, flags);
+        VMM::map(addr + (i * PAGE_SIZE), (uint64_t)physicalAddress, flags);
 #ifdef MM_DEBUG
         kdbgln("allocating virtual %lx, physical %p", addr + (i * PAGE_SIZE), physicalAddress);
 #endif
@@ -180,9 +180,9 @@ void MemoryManager::release_pages(void* pages, uint64_t count)
     for (uint64_t i = 0; i < count; i++)
     {
         void* page = (void*)((uint64_t)pages + (i * PAGE_SIZE));
-        uint64_t physicalAddress = kernelVMM.getPhysical((uint64_t)page);
+        uint64_t physicalAddress = VMM::getPhysical((uint64_t)page);
         ASSERT(physicalAddress != UINT64_MAX);
-        kernelVMM.unmap((uint64_t)page);
+        VMM::unmap((uint64_t)page);
 #ifdef MM_DEBUG
         kdbgln("releasing virtual %p, physical %lx", page, physicalAddress);
 #endif
diff --git a/kernel/src/memory/Paging.cpp b/kernel/src/memory/Paging.cpp
index 59e08552..11bff3ee 100644
--- a/kernel/src/memory/Paging.cpp
+++ b/kernel/src/memory/Paging.cpp
@@ -3,7 +3,7 @@
 #pragma GCC push_options
 #pragma GCC diagnostic ignored "-Wconversion"
 
-void Paging::PageDirectoryEntry::set_address(uint64_t addr)
+void PageDirectoryEntry::set_address(uint64_t addr)
 {
     this->Address = (addr >> 12);
 }
diff --git a/kernel/src/memory/VMM.cpp b/kernel/src/memory/VMM.cpp
index 3619e835..bd954b01 100644
--- a/kernel/src/memory/VMM.cpp
+++ b/kernel/src/memory/VMM.cpp
@@ -3,212 +3,225 @@
 #include "memory/PMM.h"
 #include "std/string.h"
 
-Paging::VirtualMemoryManager kernelVMM;
-
 // FIXME: There is a lot of duplicate code in this file. This should probably be refactored.
 
-namespace Paging
+static PageTable* PML4;
+
+void VMM::init()
 {
-    void VirtualMemoryManager::init()
+    asm volatile("mov %%cr3, %0" : "=r"(PML4));
+}
+
+void VMM::init(PageTable* cr3)
+{
+    PML4 = cr3;
+}
+
+void VMM::unmap(uint64_t virtualAddress)
+{
+    virtualAddress >>= 12;
+    uint64_t P_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PT_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PD_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PDP_i = virtualAddress & 0x1ff;
+
+    PageDirectoryEntry PDE;
+
+    PDE = PML4->entries[PDP_i];
+    PageTable* PDP;
+    if (!PDE.Present)
     {
-        asm volatile("mov %%cr3, %0" : "=r"(PML4));
+        return; // Already unmapped
+    }
+    else
+    {
+        if (PDE.LargerPages)
+        {
+            PDE.Present = false;
+            PDE.LargerPages = false;
+            PML4->entries[PDP_i] = PDE;
+            goto invalidate;
+        }
+        PDP = (PageTable*)((uint64_t)PDE.Address << 12);
     }
 
-    void VirtualMemoryManager::init(PageTable* cr3)
+    PDE = PDP->entries[PD_i];
+    PageTable* PD;
+    if (!PDE.Present)
     {
-        PML4 = cr3;
+        return; // Already unmapped
+    }
+    else
+    {
+        if (PDE.LargerPages)
+        {
+            PDE.Present = false;
+            PDE.LargerPages = false;
+            PDP->entries[PD_i] = PDE;
+            goto invalidate;
+        }
+        PD = (PageTable*)((uint64_t)PDE.Address << 12);
     }
 
-    void VirtualMemoryManager::unmap(uint64_t virtualAddress)
+    PDE = PD->entries[PT_i];
+    PageTable* PT;
+    if (!PDE.Present)
     {
-        virtualAddress >>= 12;
-        uint64_t P_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PT_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PD_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PDP_i = virtualAddress & 0x1ff;
-
-        PageDirectoryEntry PDE;
-
-        PDE = PML4->entries[PDP_i];
-        PageTable* PDP;
-        if (!PDE.Present)
+        return; // Already unmapped
+    }
+    else
+    {
+        if (PDE.LargerPages)
         {
-            return; // Already unmapped
+            PDE.LargerPages = false;
+            PDE.Present = false;
+            PD->entries[PT_i] = PDE;
+            goto invalidate;
         }
-        else
-        {
-            if (PDE.LargerPages)
-            {
-                PDE.Present = false;
-                PDE.LargerPages = false;
-                PML4->entries[PDP_i] = PDE;
-                goto invalidate;
-            }
-            PDP = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-
-        PDE = PDP->entries[PD_i];
-        PageTable* PD;
-        if (!PDE.Present)
-        {
-            return; // Already unmapped
-        }
-        else
-        {
-            if (PDE.LargerPages)
-            {
-                PDE.Present = false;
-                PDE.LargerPages = false;
-                PDP->entries[PD_i] = PDE;
-                goto invalidate;
-            }
-            PD = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-
-        PDE = PD->entries[PT_i];
-        PageTable* PT;
-        if (!PDE.Present)
-        {
-            return; // Already unmapped
-        }
-        else
-        {
-            if (PDE.LargerPages)
-            {
-                PDE.LargerPages = false;
-                PDE.Present = false;
-                PD->entries[PT_i] = PDE;
-                goto invalidate;
-            }
-            PT = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-
-        PDE = PT->entries[P_i];
-        PDE.Present = false;
-        PT->entries[P_i] = PDE;
-    invalidate:
-        asm volatile("invlpg (%0)" : : "r"(virtualAddress) : "memory");
+        PT = (PageTable*)((uint64_t)PDE.Address << 12);
     }
 
-    uint64_t VirtualMemoryManager::getPhysical(uint64_t virtualAddress)
+    PDE = PT->entries[P_i];
+    PDE.Present = false;
+    PT->entries[P_i] = PDE;
+invalidate:
+    asm volatile("invlpg (%0)" : : "r"(virtualAddress) : "memory");
+}
+
+uint64_t VMM::getPhysical(uint64_t virtualAddress)
+{
+    virtualAddress >>= 12;
+    uint64_t P_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PT_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PD_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PDP_i = virtualAddress & 0x1ff;
+
+    PageDirectoryEntry PDE;
+
+    PDE = PML4->entries[PDP_i];
+    PageTable* PDP;
+    if (!PDE.Present)
     {
-        virtualAddress >>= 12;
-        uint64_t P_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PT_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PD_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PDP_i = virtualAddress & 0x1ff;
-
-        PageDirectoryEntry PDE;
-
-        PDE = PML4->entries[PDP_i];
-        PageTable* PDP;
-        if (!PDE.Present)
-        {
-            return UINT64_MAX; // Not mapped
-        }
-        else
-        {
-            if (PDE.LargerPages) return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
-            PDP = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-
-        PDE = PDP->entries[PD_i];
-        PageTable* PD;
-        if (!PDE.Present)
-        {
-            return UINT64_MAX; // Not mapped
-        }
-        else
-        {
-            if (PDE.LargerPages) return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
-            PD = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-
-        PDE = PD->entries[PT_i];
-        PageTable* PT;
-        if (!PDE.Present)
-        {
-            return UINT64_MAX; // Not mapped
-        }
-        else
-        {
-            if (PDE.LargerPages) return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
-            PT = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-
-        PDE = PT->entries[P_i];
-        if (!PDE.Present) return UINT64_MAX;
-        return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
+        return UINT64_MAX; // Not mapped
+    }
+    else
+    {
+        if (PDE.LargerPages) return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
+        PDP = (PageTable*)((uint64_t)PDE.Address << 12);
     }
 
-    uint64_t VirtualMemoryManager::getFlags(uint64_t virtualAddress) // FIXME: Add support for larger pages to getFlags.
+    PDE = PDP->entries[PD_i];
+    PageTable* PD;
+    if (!PDE.Present)
     {
-        virtualAddress >>= 12;
-        uint64_t P_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PT_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PD_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PDP_i = virtualAddress & 0x1ff;
-
-        PageDirectoryEntry PDE;
-
-        PDE = PML4->entries[PDP_i];
-        PageTable* PDP;
-        if (!PDE.Present)
-        {
-            return 0; // Not mapped
-        }
-        else { PDP = (PageTable*)((uint64_t)PDE.Address << 12); }
-
-        PDE = PDP->entries[PD_i];
-        PageTable* PD;
-        if (!PDE.Present)
-        {
-            return 0; // Not mapped
-        }
-        else { PD = (PageTable*)((uint64_t)PDE.Address << 12); }
-
-        PDE = PD->entries[PT_i];
-        PageTable* PT;
-        if (!PDE.Present)
-        {
-            return 0; // Not mapped
-        }
-        else { PT = (PageTable*)((uint64_t)PDE.Address << 12); }
-
-        uint64_t flags = 0;
-
-        PDE = PT->entries[P_i];
-        if (PDE.UserSuper) flags |= User;
-        if (PDE.ReadWrite) flags |= ReadWrite;
-        return flags;
+        return UINT64_MAX; // Not mapped
+    }
+    else
+    {
+        if (PDE.LargerPages) return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
+        PD = (PageTable*)((uint64_t)PDE.Address << 12);
     }
 
-    void VirtualMemoryManager::map(uint64_t virtualAddress, uint64_t physicalAddress, int flags)
+    PDE = PD->entries[PT_i];
+    PageTable* PT;
+    if (!PDE.Present)
     {
-        virtualAddress >>= 12;
-        uint64_t P_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PT_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PD_i = virtualAddress & 0x1ff;
-        virtualAddress >>= 9;
-        uint64_t PDP_i = virtualAddress & 0x1ff;
+        return UINT64_MAX; // Not mapped
+    }
+    else
+    {
+        if (PDE.LargerPages) return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
+        PT = (PageTable*)((uint64_t)PDE.Address << 12);
+    }
 
-        PageDirectoryEntry PDE;
+    PDE = PT->entries[P_i];
+    if (!PDE.Present) return UINT64_MAX;
+    return PDE.Address << 12 | (virtualAddress & PAGE_SIZE);
+}
 
-        PDE = PML4->entries[PDP_i];
-        PageTable* PDP;
-        if (!PDE.Present)
+uint64_t VMM::getFlags(uint64_t virtualAddress) // FIXME: Add support for larger pages to getFlags.
+{
+    virtualAddress >>= 12;
+    uint64_t P_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PT_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PD_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PDP_i = virtualAddress & 0x1ff;
+
+    PageDirectoryEntry PDE;
+
+    PDE = PML4->entries[PDP_i];
+    PageTable* PDP;
+    if (!PDE.Present)
+    {
+        return 0; // Not mapped
+    }
+    else { PDP = (PageTable*)((uint64_t)PDE.Address << 12); }
+
+    PDE = PDP->entries[PD_i];
+    PageTable* PD;
+    if (!PDE.Present)
+    {
+        return 0; // Not mapped
+    }
+    else { PD = (PageTable*)((uint64_t)PDE.Address << 12); }
+
+    PDE = PD->entries[PT_i];
+    PageTable* PT;
+    if (!PDE.Present)
+    {
+        return 0; // Not mapped
+    }
+    else { PT = (PageTable*)((uint64_t)PDE.Address << 12); }
+
+    uint64_t flags = 0;
+
+    PDE = PT->entries[P_i];
+    if (PDE.UserSuper) flags |= User;
+    if (PDE.ReadWrite) flags |= ReadWrite;
+    return flags;
+}
+
+void VMM::map(uint64_t virtualAddress, uint64_t physicalAddress, int flags)
+{
+    virtualAddress >>= 12;
+    uint64_t P_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PT_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PD_i = virtualAddress & 0x1ff;
+    virtualAddress >>= 9;
+    uint64_t PDP_i = virtualAddress & 0x1ff;
+
+    PageDirectoryEntry PDE;
+
+    PDE = PML4->entries[PDP_i];
+    PageTable* PDP;
+    if (!PDE.Present)
+    {
+        PDP = (PageTable*)PMM::request_page();
+        ASSERT(!(PMM_DID_FAIL(PDP)));
+        memset(PDP, 0, PAGE_SIZE);
+        PDE.set_address((uint64_t)PDP);
+        PDE.Present = true;
+        PDE.ReadWrite = true;
+        if (flags & User) PDE.UserSuper = true;
+        PML4->entries[PDP_i] = PDE;
+    }
+    else
+    {
+        if (PDE.LargerPages)
         {
+            unmap(virtualAddress);
+            PDE.LargerPages = false;
             PDP = (PageTable*)PMM::request_page();
             ASSERT(!(PMM_DID_FAIL(PDP)));
             memset(PDP, 0, PAGE_SIZE);
@@ -218,33 +231,33 @@ namespace Paging
             if (flags & User) PDE.UserSuper = true;
             PML4->entries[PDP_i] = PDE;
         }
-        else
-        {
-            if (PDE.LargerPages)
-            {
-                unmap(virtualAddress);
-                PDE.LargerPages = false;
-                PDP = (PageTable*)PMM::request_page();
-                ASSERT(!(PMM_DID_FAIL(PDP)));
-                memset(PDP, 0, PAGE_SIZE);
-                PDE.set_address((uint64_t)PDP);
-                PDE.Present = true;
-                PDE.ReadWrite = true;
-                if (flags & User) PDE.UserSuper = true;
-                PML4->entries[PDP_i] = PDE;
-            }
-            PDP = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-        if ((flags & User) && !PDE.UserSuper)
-        {
-            PDE.UserSuper = true;
-            PML4->entries[PDP_i] = PDE;
-        }
+        PDP = (PageTable*)((uint64_t)PDE.Address << 12);
+    }
+    if ((flags & User) && !PDE.UserSuper)
+    {
+        PDE.UserSuper = true;
+        PML4->entries[PDP_i] = PDE;
+    }
 
-        PDE = PDP->entries[PD_i];
-        PageTable* PD;
-        if (!PDE.Present)
+    PDE = PDP->entries[PD_i];
+    PageTable* PD;
+    if (!PDE.Present)
+    {
+        PD = (PageTable*)PMM::request_page();
+        ASSERT(!(PMM_DID_FAIL(PD)));
+        memset(PD, 0, PAGE_SIZE);
+        PDE.set_address((uint64_t)PD);
+        PDE.Present = true;
+        PDE.ReadWrite = true;
+        if (flags & User) PDE.UserSuper = true;
+        PDP->entries[PD_i] = PDE;
+    }
+    else
+    {
+        if (PDE.LargerPages)
         {
+            unmap(virtualAddress);
+            PDE.LargerPages = false;
             PD = (PageTable*)PMM::request_page();
             ASSERT(!(PMM_DID_FAIL(PD)));
             memset(PD, 0, PAGE_SIZE);
@@ -254,33 +267,33 @@ namespace Paging
             if (flags & User) PDE.UserSuper = true;
             PDP->entries[PD_i] = PDE;
         }
-        else
-        {
-            if (PDE.LargerPages)
-            {
-                unmap(virtualAddress);
-                PDE.LargerPages = false;
-                PD = (PageTable*)PMM::request_page();
-                ASSERT(!(PMM_DID_FAIL(PD)));
-                memset(PD, 0, PAGE_SIZE);
-                PDE.set_address((uint64_t)PD);
-                PDE.Present = true;
-                PDE.ReadWrite = true;
-                if (flags & User) PDE.UserSuper = true;
-                PDP->entries[PD_i] = PDE;
-            }
-            PD = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-        if ((flags & User) && !PDE.UserSuper)
-        {
-            PDE.UserSuper = true;
-            PDP->entries[PD_i] = PDE;
-        }
+        PD = (PageTable*)((uint64_t)PDE.Address << 12);
+    }
+    if ((flags & User) && !PDE.UserSuper)
+    {
+        PDE.UserSuper = true;
+        PDP->entries[PD_i] = PDE;
+    }
 
-        PDE = PD->entries[PT_i];
-        PageTable* PT;
-        if (!PDE.Present)
+    PDE = PD->entries[PT_i];
+    PageTable* PT;
+    if (!PDE.Present)
+    {
+        PT = (PageTable*)PMM::request_page();
+        ASSERT(!(PMM_DID_FAIL(PT)));
+        memset(PT, 0, PAGE_SIZE);
+        PDE.set_address((uint64_t)PT);
+        PDE.Present = true;
+        PDE.ReadWrite = true;
+        if (flags & User) PDE.UserSuper = true;
+        PD->entries[PT_i] = PDE;
+    }
+    else
+    {
+        if (PDE.LargerPages)
         {
+            unmap(virtualAddress);
+            PDE.LargerPages = false;
             PT = (PageTable*)PMM::request_page();
             ASSERT(!(PMM_DID_FAIL(PT)));
             memset(PT, 0, PAGE_SIZE);
@@ -290,34 +303,18 @@ namespace Paging
             if (flags & User) PDE.UserSuper = true;
             PD->entries[PT_i] = PDE;
         }
-        else
-        {
-            if (PDE.LargerPages)
-            {
-                unmap(virtualAddress);
-                PDE.LargerPages = false;
-                PT = (PageTable*)PMM::request_page();
-                ASSERT(!(PMM_DID_FAIL(PT)));
-                memset(PT, 0, PAGE_SIZE);
-                PDE.set_address((uint64_t)PT);
-                PDE.Present = true;
-                PDE.ReadWrite = true;
-                if (flags & User) PDE.UserSuper = true;
-                PD->entries[PT_i] = PDE;
-            }
-            PT = (PageTable*)((uint64_t)PDE.Address << 12);
-        }
-        if ((flags & User) && !PDE.UserSuper)
-        {
-            PDE.UserSuper = true;
-            PD->entries[PT_i] = PDE;
-        }
-
-        PDE = PT->entries[P_i];
-        PDE.Present = true;
-        PDE.ReadWrite = flags & ReadWrite;
-        PDE.UserSuper = flags & User;
-        PDE.set_address(physicalAddress);
-        PT->entries[P_i] = PDE;
+        PT = (PageTable*)((uint64_t)PDE.Address << 12);
     }
+    if ((flags & User) && !PDE.UserSuper)
+    {
+        PDE.UserSuper = true;
+        PD->entries[PT_i] = PDE;
+    }
+
+    PDE = PT->entries[P_i];
+    PDE.Present = true;
+    PDE.ReadWrite = flags & ReadWrite;
+    PDE.UserSuper = flags & User;
+    PDE.set_address(physicalAddress);
+    PT->entries[P_i] = PDE;
 }
\ No newline at end of file
diff --git a/kernel/src/sys/exec.cpp b/kernel/src/sys/exec.cpp
index e9db4387..666b287e 100644
--- a/kernel/src/sys/exec.cpp
+++ b/kernel/src/sys/exec.cpp
@@ -47,7 +47,7 @@ void sys_exec(Context* context, const char* pathname)
         return;
     }
 
-    if (memusage > PMM::get_free())
+    if ((uint64_t)memusage > PMM::get_free())
     {
         MemoryManager::release_pages((void*)allocated_stack, TASK_PAGES_IN_STACK);
         context->rax = -ENOMEM;
diff --git a/kernel/src/sys/mem.cpp b/kernel/src/sys/mem.cpp
index 0e946673..ea0686f4 100644
--- a/kernel/src/sys/mem.cpp
+++ b/kernel/src/sys/mem.cpp
@@ -24,7 +24,7 @@ void sys_mmap(Context* context, void* address, size_t size, int flags)
     {
         kdbgln("sys_mmap: %ld pages at address %p, %s", size / PAGE_SIZE, address,
                real_flags & MAP_READ_WRITE ? "rw" : "ro");
-        if (kernelVMM.getPhysical((uint64_t)address) != (uint64_t)-1) // Address is already used.
+        if (VMM::getPhysical((uint64_t)address) != (uint64_t)-1) // Address is already used.
         {
             kdbgln("attempt to mmap an already mapped address");
             context->rax = MAP_FAIL(ENOMEM);
@@ -78,7 +78,7 @@ void sys_munmap(Context* context, void* address, size_t size)
         context->rax = -EINVAL;
         return;
     }
-    uint64_t flags = kernelVMM.getFlags((uint64_t)address);
+    uint64_t flags = VMM::getFlags((uint64_t)address);
     if (!(flags & MAP_USER))
     {
         kdbgln("munmap failed: attempted to unmap a kernel page");