Adjust bounds for page table filling. Some maths was wrong

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,18 @@
+---
+name: Bug report
+about: Tell us about something gone wrong
+title: ''
+labels: bug
+assignees: TheCurle
+
+---
+
+**What went wrong?**  
+We need to know what the actual problem to be solved is - obviously!
+
+**How can we recreate the issue?**  
+Having solid steps to reproduce the problem helps a ton!  
+Please put it in terms of "Step 1: Boot, Step 2: Press this combination of keys: `alt + F20 + J`..."
+
+**What do you think went wrong?**  
+If you have any vague suggestions or have investigated the issue and know roughly what's wrong, feel free to put it here. Otherwise, don't worry.

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,16 @@
+---
+name: Feature request
+about: Got a cool idea for new functionality?
+title: ''
+labels: enhancement
+assignees: TheCurle
+
+---
+
+**Describe the feature**
+What's the actual feature? How would it be activated? What would it allow you to do?
+What's the benefit, and why is it worth the work required?
+
+**Alternatives?**
+If the feature cannot be added for whatever reason, is there a reasonable compromise you have in mind?
+Who knows, this alternative may be introduced alongside the main feature.

CMakeLists.txt

@@ -24,6 +24,7 @@ SET(src_files
     ${CMAKE_SOURCE_DIR}/chroma/system/memory/abstract_allocator.c
     ${CMAKE_SOURCE_DIR}/chroma/system/memory/physmem.c
     ${CMAKE_SOURCE_DIR}/chroma/system/drivers/keyboard.c
+    ${CMAKE_SOURCE_DIR}/chroma/system/drivers/elf.c
 )
 
 SET(lib_files

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 Curle
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

chroma/inc/kernel/boot/boot.h

@@ -11,6 +11,30 @@
 extern "C" {
 #endif
 
+/* ELF headers hate me.
+ * Let's do this the hard way. */
+
+#define ELF_IDENT_MAGIC_OFF       0x0
+#define ELF_IDENT_CLASS_OFF       0x4
+#define ELF_IDENT_DATA_OFF        0x5
+#define ELF_IDENT_VERSION_OFF     0x6
+#define ELF_IDENT_OSABI_OFF       0x7
+#define ELF_IDENT_ABI_VERSION_OFF 0x8
+#define ELF_IDENT_PAD_OFF         0x9
+#define ELFTYPE_OFF               0x10
+#define ELFMACHINE_OFF            0x12
+#define ELFVERSION_OFF            0x14
+#define ELFENTRY_OFF              0x18
+#define ELFPHOFF_OFF              0x20
+#define ELFSHOFF_OFF              0x28 
+#define ELFFLAGS_OFF              0x30
+#define ELFEHSIZE_OFF             0x34
+#define ELFPHENTSIZE_OFF          0x36
+#define ELFPHNUM_OFF              0x38
+#define ELFSHENTSIZE_OFF          0x3A
+#define ELFSHNUM_OFF              0x3C
+#define ELFSHSTRNDX_OFF           0x40
+
 #define BOOT_MAGIC "BOOT"
 
 /* minimum protocol level:
@@ -108,30 +132,6 @@ typedef struct {
 } __attribute__((packed)) bootinfo;
 
 
-typedef struct {
-  uint32_t Magic;
-  uint8_t Class;
-  uint8_t Endianness;
-  uint8_t Version;
-  uint8_t ABI;
-  uint8_t ABIVersion;
-  uint8_t Unused[7];
-  uint16_t Type;
-  uint16_t TargetArchitecture;
-  uint32_t ELFVersion;
-  size_t EntryPoint;
-  size_t ProgramHeadersTable;
-  size_t SectionHeadersTable;
-  uint32_t Flags;
-  uint16_t ELFHeaderSize;
-  uint16_t ProgramHeadersEntrySize;
-  uint16_t ProgramHeaderEntries;
-  uint16_t SectionHeadersEntrySize;
-  uint16_t SectionHeaderEntries;
-  uint16_t SectionHeaderNameEntry;
-  uint8_t End;
-} __attribute__((packed)) ELF64Header_t;
-
 
 #ifdef  __cplusplus
 }

chroma/inc/kernel/chroma.h

@@ -69,6 +69,8 @@ void InitPrint();
 void SetupInitialGDT();
 void SetupIDT();
 
+int ParseKernelHeader(size_t InitrdPtr);
+
 int Main();
 
 void Exit();

chroma/inc/kernel/system/memory.h

@@ -8,8 +8,6 @@
  ***     Chroma       ***
  ***********************/
 
-size_t KernelLocation;
-
 
 /************************************************
 *    C O N S T A N T S   A N D   M A C R O S
@@ -30,6 +28,11 @@ size_t KernelLocation;
 
 #define REINTERPRET_CAST(target, intermediate, value) ((target*)((intermediate*)value))
 
+#define FIXENDIAN64(x) __builtin_bswap64(x)
+#define FIXENDIAN32(x) __builtin_bswap32(x)
+#define FIXENDIAN16(x) __builtin_bswap16(x)
+
+
 #define CONCAT(x, y) x ## y
 #define CONCAT2(x, y) CONCAT(x, y)
 #define ASSERT(exp, error) \
@@ -54,7 +57,8 @@ size_t KernelLocation;
 #define ERR_RESERVED 0x8
 #define ERR_INST     0x10
 
-#define ELF64MAGIC 0x7F454c46
+#define ELF64MAGIC   0x7F454c46
+#define ELF64MAGICBE 0x464c457F
 
 
 /*
@@ -106,7 +110,7 @@ size_t KernelLocation;
 
 #define MMIO_REGION         0xFFFFFFFFF8000000ull // Cannot move!
 #define FB_REGION           0xFFFFFFFFFC000000ull // Cannot move!
-#define FB_PHYSICAL         0x00000000E0000000ull // Physical location of the Framebuffer
+#define FB_PHYSICAL         0x00000000FD000000ull // Physical location of the Framebuffer
 #define KERNEL_REGION       0xFFFFFFFFFFE00000ull // -2MiB, from bootloader
 
 #define USER_REGION         0x00007FFFFFFFFFFFull // Not needed yet, but we're higher half so we might as well be thorough

chroma/kernel.c

@@ -20,48 +20,13 @@ address_space_t KernelAddressSpace;
 
 int Main(void) {
     KernelAddressSpace = (address_space_t) {0};
-    KernelLocation = 0x112600;
 
     SerialPrintf("\r\n[ boot] Booting Chroma..\r\n");
     SerialPrintf("[ boot] Kernel loaded at 0x%p, ends at 0x%p, is %d bytes long.\r\n", KernelAddr, KernelEnd, KernelEnd - KernelAddr);
     SerialPrintf("[ boot] Initrd is physically at 0x%p, and is %d bytes long.\r\n", bootldr.initrd_ptr, bootldr.initrd_size);
+    SerialPrintf("[ boot] Initrd's header is 0x%p\r\n", FIXENDIAN32(*((volatile uint32_t*)(bootldr.initrd_ptr))));
    
-    SerialPrintf("[ boot] Searching for kernel... Constants start at 0x%p\r\n", &_kernel_text_start);
+    ParseKernelHeader(bootldr.initrd_ptr);
-    // We stop at the constants in the kernel, otherwise we'll read the constant ELF64MAGIC which is stored inside the kernel...
-    
-    size_t headerLoc = 0;
-    for(size_t i = KernelAddr; i < KernelEnd; i++) {
-        if(i < (size_t) (&_kernel_text_start) - KernelAddr) {
-            if(*((volatile uint32_t*)(i)) == ELF64MAGIC) {
-                SerialPrintf("[ boot] Matched kernel header at 0x%p.\r\n", i);
-            }
-        }
-    }
-
-    int flag = 0;
-
-    if(headerLoc) {
-        ELF64Header_t* PotentialKernelHeader = (ELF64Header_t*) &headerLoc;
-        SerialPrintf(
-            "[ boot] Considering ELF with:\r\n\tBitness %d\r\n\tEntry point 0x%p\r\n\tFile type %s : %d\r\n\tArchitecture %s : %d\r\n",
-            PotentialKernelHeader->Class == 2 ? 64 : 32, PotentialKernelHeader->EntryPoint, PotentialKernelHeader->Type == 0x02 ? "EXECUTABLE" : "OTHER", PotentialKernelHeader->Type, PotentialKernelHeader->TargetArchitecture == 0x3E ? "AMD64" : "OTHER", PotentialKernelHeader->TargetArchitecture);
-        if(PotentialKernelHeader->EntryPoint == KernelAddr) {
-            SerialPrintf("[ boot] Header at 0x%p matches kernel header.\r\n", headerLoc);
-            flag = 1;
-        }
-
-        if(!flag) {
-
-            for(size_t i = 0; i < 8; i++) {
-                SerialPrintf("[ boot] Header dump part %d: 0x%x\r\n", i, *((volatile uint32_t*)(headerLoc + i)));
-            }
-        }
-    }
-
-    if(!flag) {
-        SerialPrintf("[ boot] Unable to find kernel in memory. Fatal error.\r\n");
-        //for(;;) {}
-    }
 
     SerialPrintf("[ boot] The bootloader has put the paging tables at 0x%p.\r\n", ReadControlRegister(3));
 

chroma/system/drivers/elf.c

@@ -0,0 +1,91 @@
+#include <kernel/chroma.h>
+/************************
+ *** Team Kitty, 2020 ***
+ ***     Chroma       ***
+ ***********************/
+
+/*
+ * This file provides utility functions for parsing ELF headers.
+ *  This exists so that the kernel can find itself for remapping, 
+ *   but I may end up using ELF as the kernel's executable format.
+ *  Writing an ELF loader is on the to-do list, after all.
+ ! This needs to be cleaned up.
+ ! This creates a mess of numbers on the print
+ ! This is hacky and hardcoded as heck and needs to be fixed
+*/
+extern size_t KernelLocation;
+
+int ParseKernelHeader(size_t InitrdPtr) {
+    int flag = 0;
+    
+    SerialPrintf("[ boot] Searching for kernel... Constants start at 0x%p / 0x%p\r\n", ((size_t) (&_kernel_text_start) - KernelAddr) + InitrdPtr, (size_t) (&_kernel_text_start));
+    // We stop at the constants in the kernel, otherwise we'll read the constant ELF64MAGIC which is stored inside the kernel...
+ 
+    size_t headerLoc = 0;
+    for(size_t i = InitrdPtr; i < ((size_t) (&_kernel_text_start) - KernelAddr) + InitrdPtr; i++) {
+        if(*((volatile uint32_t*)(i)) == ELF64MAGIC) {
+            SerialPrintf("[ boot] Matched kernel header at 0x%p.\r\n", i);
+            headerLoc = i;
+        }
+
+        if(FIXENDIAN32(*((volatile uint32_t*)(i))) == ELF64MAGIC) {
+            SerialPrintf("[ boot] Matched little-endian kernel header at 0x%p.\r\n", i);
+            headerLoc = i;
+        }
+    }
+
+    if(headerLoc) {
+        /* For whatever reason, reading a size_t here fails. The max that seems to work is uint16_t, so we read in the 
+         *  64 bit address by constructing it from 4 individual reads.
+         * Note that these 4 reads are little endian, so we need to flip them around individually
+         */
+        uint16_t EntryPoint0 =  FIXENDIAN16(*((volatile uint16_t*)(headerLoc + ELFENTRY_OFF)));
+        uint16_t EntryPoint1 =  FIXENDIAN16(*((volatile uint16_t*)(headerLoc + ELFENTRY_OFF + 2)));
+        uint16_t EntryPoint2 =  FIXENDIAN16(*((volatile uint16_t*)(headerLoc + ELFENTRY_OFF + 4)));
+        uint16_t EntryPoint3 =  FIXENDIAN16(*((volatile uint16_t*)(headerLoc + ELFENTRY_OFF + 6)));
+        size_t EntryPoint = ((size_t) EntryPoint0 << 48) | ((size_t) EntryPoint1 << 32) | ((size_t) EntryPoint2 << 16) | ((size_t) EntryPoint3);
+
+        /* At this point, EntryPoint is a little-endian 64 bit integer. That means we have to fix its endianness in order to read it */
+        SerialPrintf("[ boot] Fixing entry point from 0x%p to 0x%p\r\n", EntryPoint, FIXENDIAN64(EntryPoint));
+        EntryPoint = FIXENDIAN64(EntryPoint);
+
+        /* Now we can continue as normal */
+        uint8_t HeaderClass = *((volatile uint8_t*)(headerLoc + ELF_IDENT_CLASS_OFF));
+        uint16_t ExecutableType = (uint16_t) *((volatile uint8_t*)(headerLoc + ELFTYPE_OFF));
+        uint16_t MachineType = (uint16_t) *((volatile uint8_t*)(headerLoc + ELFMACHINE_OFF));
+
+    
+        SerialPrintf(
+            "[ boot] ELF header at 0x%p.\r\n\tConsidering ELF with:\r\n\tBitness %d: %d\r\n\tEntry point 0x%p\r\n\tFile type %s : 0x%x\r\n\tArchitecture %s : 0x%x\r\n",
+            headerLoc,
+             HeaderClass == 2 ? 64 : 32,
+                 HeaderClass,
+            EntryPoint,
+            ExecutableType == FIXENDIAN16(0x0200) ? "EXECUTABLE" : "OTHER", 
+                FIXENDIAN16(ExecutableType), 
+            MachineType == FIXENDIAN16(0x3E00) ? "AMD64" : "OTHER", 
+                FIXENDIAN16(MachineType));
+        
+
+        
+        
+        if(EntryPoint == (size_t) (&_kernel_text_start)) {
+            SerialPrintf("[ boot] Header at 0x%p matches kernel header.\r\n", headerLoc);
+            flag = 1;
+            // At this point, we've found the right ELF64 executable!
+            // Great, now we can map it into the proper place
+            KernelLocation = headerLoc;
+        }
+
+        if(!flag) {
+
+            for(char i = 0; i < 64; i++) {
+                SerialPrintf("[ boot] Header dump part %x: 0x%x\r\n", i, *((volatile uint8_t*)(headerLoc + i)));
+            }
+        }
+    }
+
+    return flag;
+
+}
+

chroma/system/memory/paging.c

@@ -52,6 +52,8 @@
 extern size_t _kernel_rodata_start;
 extern size_t _kernel_data_start;
 
+size_t KernelLocation;
+
 //__attribute__((aligned(4096))) static size_t Pagetable[512] = {0};
 
 #define LAST_ENTRY 0xFF8
@@ -151,8 +153,9 @@ void InitPaging() {
 
     //TODO: Disallow execution of rodata and data, and bootldr/environment
     for(void* Address = CAST(void*, KERNEL_REGION);
-            Address < CAST(void*, KERNEL_REGION + (KernelEnd - KernelAddr)); // Lower half of Kernel
+            Address < CAST(void*, KERNEL_REGION + (KernelEnd - KernelAddr));
             Address = CAST(void*, CAST(char*, Address) + PAGE_SIZE)) {
+                SerialPrintf("[  mem] Mapping 0x%p to 0x%p, relative to kernel at 0x%p\r\n", (CAST(size_t, Address) - KERNEL_REGION) + KernelLocation, Address, (CAST(size_t, Address) - KERNEL_REGION));
                 MapVirtualMemory(&KernelAddressSpace, Address, (CAST(size_t, Address) - KERNEL_REGION) + KernelLocation, MAP_EXEC);
     }
 
@@ -161,9 +164,9 @@ void InitPaging() {
             Address = CAST(void*, CAST(char*, Address) + PAGE_SIZE)) {
                 MapVirtualMemory(&KernelAddressSpace, Address, (CAST(size_t, Address) - KERNEL_REGION) + KERNEL_PHYSICAL_2, MAP_EXEC);
     }*/
-
+    SerialPrintf("[  mem] Framebuffer at 0x%p, is 0x%p long. Mapping to 0x%p.\r\n", bootldr.fb_ptr, bootldr.fb_size, FB_REGION);
     for(void* Address = CAST(void*, FB_REGION);
-            Address < CAST(void*, 0x200000);     // TODO: Turn this into a calculation with bootldr.fb_size
+            Address < CAST(void*, bootldr.fb_size + FB_REGION);
             Address = CAST(void*, CAST(char*, Address) + PAGE_SIZE)) {
                 MapVirtualMemory(&KernelAddressSpace, Address, (CAST(size_t, Address) - FB_REGION) + FB_PHYSICAL, MAP_WRITE);
     }

chroma/system/memory/temp_storage/legacypaging.c

@@ -0,0 +1,310 @@
+
+void InitPagingT() {
+
+    size_t* PML4 = (size_t*) 0xFFA000; // Layer 4
+    size_t* PDPE_RAM = (size_t*) 0xFFE000; // Layer 3, contains map for the first 4GB of RAM
+    size_t* PDE_RAM = (size_t*) 0xFFF000;
+
+    size_t* PDPE_KERNEL = (size_t*) 0xFFB000; // Layer 3, contains map for the Kernel and everything it needs to run.
+    size_t* PDE_KERNEL_FB = (size_t*) 0xFFC000; // Layer 2, contains map for the linear framebuffer.
+
+    size_t* PT_KERNEL = (size_t*) 0xFFD000; // Layer 1, the page table for the kernel itself.
+
+    size_t fb_ptr = (size_t) &fb;
+
+    SET_ADDRESS(PML4, PDPE_RAM); // 3rd Layer entry for RAM
+    SET_ADDRESS(PML4 + LAST_ENTRY, PDPE_KERNEL); // 3rd Layer entry for Kernel
+
+    SET_ADDRESS(PDPE_KERNEL + LAST_ENTRY, PDE_KERNEL_FB); // 2nd Layer entry for the framebuffer
+
+    // Set the 480th entry (PDE_KERNEL_FB + (480 * 8))
+    // To the framebuffer + flags
+    SET_ADDRESS(PDE_KERNEL_FB + 3840, USERWRITEABLE_FLAGS(fb_ptr)); 
+
+    // In 4 byte increments, we're gonna map 3840 (the framebuffer)
+    // Up to (4096 - 8) in the PDE_KERNEL_FB with 2MB paging.
+    size_t MappingIterations = 1;
+    for(size_t i = 3844; i < 4088; i += 4) {
+        SET_ADDRESS(PDE_KERNEL_FB + i, USERWRITEABLE_FLAGS(fb_ptr) + (MappingIterations * (2 * MiB)));
+        MappingIterations++;
+    }
+
+    // Now we map the last entry of PDE_KERNEL_FB to our Page Table
+    SET_ADDRESS(PDE_KERNEL_FB + LAST_ENTRY, PT_KERNEL);
+
+    // Mapping the kernel into the page tables....
+
+    SET_ADDRESS(PT_KERNEL, 0xFF8001); // bootldr, bootinfo
+    SET_ADDRESS(PT_KERNEL + 8, 0xFF9001); // environment
+
+    // Map the kernel itself
+    SET_ADDRESS(PT_KERNEL + 16, KernelAddr + 1);
+
+    // Iterate through the pages, identity mapping each one
+    MappingIterations = 1;
+    size_t MappingOffset = 0x14;
+    for(size_t i = 0; i < ((KernelEnd - KernelAddr) >> 12); i++) {
+        // Page Table + (0x10 increasing by 0x04 each time) = x * 4KiB
+        SET_ADDRESS(PT_KERNEL + MappingOffset, (MappingIterations * (4 * KiB)));
+        MappingOffset += 4;
+        MappingIterations++;
+    }
+
+    // Now we need to map the core stacks. Top-down, from 0xDFF8
+    // There's always at least one core, so we do that one fixed.
+    // TODO: Account for 0-core CPUs
+    SET_ADDRESS(PT_KERNEL + LAST_ENTRY, 0xF14003);
+    MappingIterations = 1;
+    // For every core:
+    for(size_t i = 0; i < (bootldr.numcores + 3U) >> 2; i++) {
+        // PT_KERNEL[512 - (iterations + 1)] = 0x14003 + (iterations * page-width) 
+        SET_ADDRESS(PT_KERNEL + LAST_ENTRY - (MappingIterations * 8), 0xF14003 + (4096 * MappingIterations));
+        MappingIterations++;
+    }
+
+    SET_ADDRESS(PDPE_RAM, PDE_RAM + PAGE_PRESENT + PAGE_RW);
+    SET_ADDRESS(PDPE_RAM + 8, 0xF10000 + PAGE_PRESENT + PAGE_RW);
+    SET_ADDRESS(PDPE_RAM + 16, 0xF11000 + PAGE_PRESENT + PAGE_RW);
+    SET_ADDRESS(PDPE_RAM + 24, 0xF12000 + PAGE_PRESENT + PAGE_RW);
+    
+    // Identity map 4GB of ram
+    // Each page table can only hold 512 entries, but we
+    // just set up 4 of them - overflowing PDE_RAM (0xF000)
+    // will take us into 0x10000, into 0x11000, into 0x120000.
+    for(size_t i = 0; i < 512 * 4/*GB*/; i++) {
+        // add PDE_RAM, 4
+        // mov eax, 0x83
+        // add eax, 2*1024*1024
+        SET_ADDRESS(PDE_RAM + (i * 4), USERWRITEABLE_FLAGS(i * (2 * MiB)));
+    }
+
+    // Map first 2MB of memory
+    SET_ADDRESS(PDE_RAM, 0xF13000 + PAGE_PRESENT + PAGE_RW);
+
+    for(size_t i = 0; i < 512; i++) {
+        SET_ADDRESS(0xF13000 + i * 4, i * (4 * KiB) + PAGE_PRESENT + PAGE_RW);
+    }
+
+    // 0xA000 should now contain our memory map.
+
+}
+
+void TraversePageTables() {
+
+}
+
+
+void InitPagingOldImpl() {
+
+    // Disable paging so that we can work with the pagetable
+    //size_t registerTemp = ReadControlRegister(0);
+    //UNSET_PGBIT(registerTemp);
+    //WriteControlRegister(0, registerTemp);
+
+    // Clear space for our pagetable
+    size_t PagetableDest = 0x1000;
+    memset((char*)PagetableDest, 0, 4096);
+
+    // Start setting pagetable indexes
+    *((size_t*)PagetableDest) = 0x2003; // PDP at 0x2000, present & r/w
+    *((size_t*)PagetableDest + 0x1000) = 0x3003; // PDT at 0x3000, present & r/w
+    *((size_t*)PagetableDest + 0x2000) = 0x4003; // PT at 0x4000, present & r/w
+
+    size_t value = 0x3;
+    size_t offset = 8;
+    for(size_t i = 0; i < 512; i++) { // 512 iterations (entries into the page table)
+        *((size_t*) PagetableDest + offset) = value; // We're setting 512 bytes with x003
+        // (identity mapping the first 4 megabytes of memory)
+        // (mapping the page table to itself)
+        value += 4096; // Point to start of next page
+        offset += 8; // + 8 bytes (next entry in list)
+    }
+
+    // Enable PAE paging
+    size_t reg = ReadControlRegister(4);
+    SET_PAEBIT(reg);
+    WriteControlRegister(4, reg);
+
+    WriteControlRegister(3, PagetableDest);
+    
+}
+
+
+/*    size_t registerTemp = ReadControlRegister(4);
+    if(registerTemp & (1 << 7)) {
+        TOGGLE_PGEBIT(registerTemp);
+        WriteControlRegister(4, registerTemp);
+    }
+
+    if(registerTemp & (1 << 7))
+        WriteControlRegister(4, registerTemp ^ (1 << 7));
+
+    size_t CPUIDReturn;
+    asm volatile("cpuid" : "=d" (CPUIDReturn) : "a" (0x80000001) : "%rbx", "%rcx");
+
+    if(CPUIDReturn & (1 << 26)) {
+        SerialPrintf("System supports 1GB pages.\r\n");
+        
+        if(registerTemp & (1 << 12)) {
+            SerialPrintf("PML5 paging available - using that instead.\r\n");
+
+            if(MemorySize > (1ULL << 57))
+                SerialPrintf("System has over 128Petabytes of RAM. Please consider upgrading the OS on your supercomputer.\r\n");                
+            
+            size_t MaxPML5 = 1;
+            size_t MaxPML4 = 1;
+            size_t MaxPDP = 512;
+
+            size_t LastPML4Entry = 512;
+            size_t LastPDPEntry = 512;
+
+            size_t MemorySearchDepth = MemorySize;
+
+            while(MemorySearchDepth > (256ULL << 30)) {
+                MaxPML5++; 
+                MemorySearchDepth -= (256ULL << 30);
+            }
+
+            if(MaxPML5 > 512)
+                MaxPML5 = 512;
+            
+            if(MemorySearchDepth) {
+                LastPDPEntry = ( (MemorySearchDepth + ((1 << 30) - 1)) & (~0ULL << 30)) >> 30;
+
+                if(MaxPML5 > 512)
+                    MaxPML5 = 512;
+                
+            }
+
+            size_t PML4Size = PAGETABLE_SIZE * MaxPML5;
+            size_t PDPSize = PML4Size * MaxPML4;
+
+            size_t PML4Base = AllocatePagetable(PML4Size + PDPSize);
+            size_t PDPBase = PML4Base + PML4Size;
+
+            for(size_t PML5Entry = 0; PML5Entry < MaxPML5; PML5Entry++) {
+                Pagetable[PML5Entry] = PML4Base + (PML5Entry << 12);
+
+                if(PML5Entry == (MaxPML5 - 1))
+                    MaxPML4 = LastPML4Entry;
+
+                for(size_t PML4Entry = 0; PML4Entry < MaxPML4; PML4Entry++) {
+
+                    ((size_t*) Pagetable[PML5Entry])[PML4Entry] = PDPBase + (((PML5Entry << 9) + PML5Entry) << 12);
+
+                    if( (PML5Entry == (MaxPML5 - 1)) && (PML4Entry == (MaxPML4 -1)) )
+                        MaxPDP = LastPDPEntry;
+                    
+                    for(size_t PDPEntry = 0; PDPEntry < MaxPDP; PDPEntry++) {
+                        ((size_t* ) ((size_t* ) Pagetable[PML5Entry])[PML4Entry])[PDPEntry] = ( ((PML5Entry << 18) + (PML4Entry << 9) + PDPEntry) << 30) | (0x83);
+                    }
+
+                    ((size_t* ) Pagetable[PML5Entry])[PML4Entry] |= 0x3;
+                }
+
+                Pagetable[PML5Entry] |= 0x3;
+            }
+        } else {
+            SerialPrintf("PML4 available - using that instead.\r\n");
+            size_t MemorySearchDepth = MemorySize;
+
+            if(MemorySearchDepth > (1ULL << 48))
+                SerialPrintf("RAM limited to 256TB.\r\n");
+            
+            size_t MaxPML4 = 1;
+            size_t MaxPDP = 512;
+
+            size_t LastPDPEntry = 512;
+
+            while(MemorySearchDepth > (512ULL << 30)) {
+                MaxPML4++;
+                MemorySearchDepth -= (512ULL << 30);
+            }
+
+            if(MaxPML4 > 512)
+                MaxPML4 = 512;
+
+            if(MemorySearchDepth) {
+                LastPDPEntry = ( (MemorySearchDepth + ((1 << 30) - 1)) & (~0ULL << 30)) >> 30;
+
+                if(LastPDPEntry > 512)
+                    LastPDPEntry = 512;
+            }
+
+            size_t PDPSize = PAGETABLE_SIZE * MaxPML4;
+            size_t PDPBase = AllocatePagetable(PDPSize);
+
+            for(size_t PML4Entry = 0; PML4Entry < MaxPML4; PML4Entry++) {
+                Pagetable[PML4Entry] = PDPBase + (PML4Entry << 12);
+
+                if(PML4Entry == (MaxPML4 - 1)) {
+                    MaxPDP = LastPDPEntry;
+                }
+
+                for(size_t PDPEntry = 0; PDPEntry < MaxPDP; PDPEntry++) {
+                    ((size_t* ) Pagetable[PML4Entry])[PDPEntry] = (((PML4Entry << 9) + PDPEntry) << 30) | 0x83;
+                }
+
+                Pagetable[PML4Entry] |=  0x3;
+            }
+        }
+    } else {
+        SerialPrintf("System does not support 1GB pages - using 2MiB paging instead.\r\n");
+
+        size_t MemorySearchDepth = MemorySize;
+
+        if(MemorySearchDepth > (1ULL << 48)) {
+            SerialPrintf("Usable RAM is limited to 256TB, and the page table alone will use 1GB of space in memory.\r\n");
+        }
+
+        size_t MaxPML4 = 1, MaxPDP = 512, MaxPD = 512, LastPDPEntry = 1;
+
+        while(MemorySearchDepth > (512ULL << 30)) {
+            MaxPML4++;
+            MemorySearchDepth -= (512ULL << 30);
+        }
+
+        if(MaxPML4 > 512)
+            MaxPML4 = 512;
+
+        if(MemorySearchDepth) {
+            LastPDPEntry = ((MemorySearchDepth + ((1 << 30) - 1)) & (~0ULL << 30)) >> 30;
+
+            if(LastPDPEntry > 512)
+                LastPDPEntry = 512;
+        }
+
+        size_t PDPSize = PAGETABLE_SIZE * MaxPML4;
+        size_t PDSize = PDPSize * MaxPDP;
+
+        size_t PDPBase = AllocatePagetable(PDPSize + PDSize);
+        size_t PDBase = PDPBase + PDSize;
+
+        for(size_t PML4Entry = 0; PML4Entry < MaxPML4; PML4Entry++) {
+            Pagetable[PML4Entry] = PDBase + (PML4Entry << 12);
+
+            if(PML4Entry == (MaxPML4 - 1)) {
+                MaxPDP = LastPDPEntry;
+            }
+
+            for(size_t PDPEntry = 0; PDPEntry < MaxPDP; PDPEntry++) {
+                ( (size_t* ) Pagetable[PML4Entry])[PDPEntry] = PDBase + (((PML4Entry << 9) + PDPEntry) << 12);
+
+                for(size_t PDEntry = 0; PDEntry < MaxPD; PDEntry++) {
+                    ( (size_t* )  ((size_t*) Pagetable[PML4Entry])[PDPEntry])[PDEntry] = (( (PML4Entry << 18) + (PDPEntry << 9) + PDPEntry) << 21) | 0x83;
+                }
+
+                ( (size_t* ) Pagetable[PML4Entry])[PDPEntry] |= 0x3;
+            }
+
+            Pagetable[PML4Entry] |= 0x3;
+        }
+    }
+
+    WriteControlRegister(3, Pagetable);
+
+    registerTemp = ReadControlRegister(4);
+    if(!(registerTemp & (1 << 7))) {
+        TOGGLE_PGEBIT(registerTemp);
+        WriteControlRegister(4, registerTemp);
+    }*/

chroma/system/memory/temp_storage/paging.c

@@ -0,0 +1,379 @@
+#include <kernel/chroma.h>
+#include <lainlib/lainlib.h>
+
+/************************
+ *** Team Kitty, 2020 ***
+ ***     Chroma       ***
+ ***********************/
+
+/****************************************
+ *  W O R K    I N     P R O G R E S S  *
+ ****************************************
+ *
+ * This file contains functions for virtual memory management.
+ * 
+ * Virtual Memory Management is still a work in progress.
+ * The functions here are hold-offs from old versions of the software implemented here, as well as from the EFI version of Chroma, called Sync.
+ * 
+ * There, these functions worked, but here, under BIOS, it's a lot more difficult.
+ * It will take some time to get these functions working.
+ * 
+ * The general plan, being that the BOOTBOOT loader has given us static addresses for all of our doodads,
+ *  is to keep the core kernel where it is (FFFFFFFFFFE00000) and load in modules and libraries around it.
+ * 
+ * We start in the higher half, so we'll dedicate the lower half (7FFFFFFFFFFF and below) to userspace.
+ * 
+ * That means we have about 3 terabytes of RAM for the kernel.
+ *  This will be identity mapped, always.
+ * 
+ * Handily, since most modern processors ignore the highest 2 bytes of a virtual address, and the kernel
+ *  is mapped to 0x80000000000 and above, we can use the nomenclature:
+ *      * 0x00007FFFFFFFFFFF and below is user space.
+ *      * 0xFFFF800000000000 and above is kernel space.
+ *  The processor will ignore the first 4 chars, and this provides a great deal of readability for the
+ *   future of the kernel.
+ * 
+ * We'll have a kernel heap mapped into this kernel space, as well as a kernel stack (for task switching and error tracing).
+ *  These will be 1GB each.
+ *      We may have to increase this in the future, once Helix is fully integrated.
+ *      Helix will take a lot of memory, as it is a fully featured 3D engine. We may have to implement things like
+ *       texture streaming and mipmapping. Minimising RAM usage is NOT a priority for me, but it would be nice
+ *        to have a minimum requirement above 32GB.
+ * 
+ *      // TODO: Expand Kernel Heap
+ * 
+ * 
+ * //TODO: there are lots of calls to AllocateFrame here, those need to be separated out into AllocateZeroFrame if necessary.
+ * 
+ * 
+ */ 
+
+extern size_t _kernel_text_start;
+extern size_t _kernel_rodata_start;
+extern size_t _kernel_data_start;
+
+//__attribute__((aligned(4096))) static size_t Pagetable[512] = {0};
+
+#define LAST_ENTRY 0xFF8
+
+#define SET_ADDRESS(a,b) ((*(size_t*) (a)) = (size_t) b)
+
+/*
+ * It turns out it's useful to have macros for the standard
+ * data size units.
+ * 
+ * Who would've thoguht?
+ */
+
+#define KiB 1 * 1024
+#define MiB 1 * 1024 * KiB
+
+
+#define PAGE_PRESENT 1
+#define PAGE_RW      2
+#define PAGE_USER    4
+#define PAGE_GLOBAL  8
+
+
+#define USERWRITEABLE_FLAGS(a) ((a & 0xFFFFFF00) + 0x83)
+
+// The AbstractAllocator control struct
+static allocator_t Allocator = NULL;
+// The AbstractAllocator Ticketlock.
+static ticketlock_t AllocatorLock = {0};
+
+// Entries to help allocate the Kernel Stack
+static list_entry_t StackFreeList;
+static ticketlock_t StackLock = {0};
+static void* StackPointer = (void*) KERNEL_STACK_REGION;
+
+// A temporary itoa function for better debugging..
+const char* IntToAscii(int In) {
+    char* OutputBuffer = "    ";
+
+    size_t Temp, i = 0, j = 0;
+
+    do {
+        Temp = In % 10;
+        OutputBuffer[i++] = (Temp < 10) ? (Temp + '0') : (Temp + 'a' - 10);
+    } while (In /= 10);
+
+    OutputBuffer[i--] = 0;
+
+    for(j = 0; j < i; j++, i--) {
+        Temp = OutputBuffer[j];
+        OutputBuffer[j] = OutputBuffer[i];
+        OutputBuffer[i] = Temp;
+    }
+
+    return OutputBuffer;
+
+}
+
+
+void InitPaging() {
+    StackFreeList = (list_entry_t) { &StackFreeList, &StackFreeList };
+
+    size_t Size = AlignUpwards(AllocatorSize(), PAGE_SIZE);
+    Allocator = PhysAllocateZeroMem(Size);
+    Allocator = CreateAllocatorWithPool(Allocator, Size);
+
+    SerialPrintf("[  Mem] Everything preallocated for paging.\n");
+
+    KernelAddressSpace = (address_space_t) {
+        .Lock = {0},
+        .PML4 = PhysAllocateZeroMem(PAGE_SIZE)
+    };
+
+    size_t* Pagetable = KernelAddressSpace.PML4;
+
+    //SerialPrintf("[  Mem] About to identity map the higher half.\n");
+    // Identity map the higher half
+    for(int i = 256; i < 512; i++) {
+        Pagetable[i] = (size_t)PhysAllocateZeroMem(PAGE_SIZE);
+        Pagetable[i] = (size_t)(((char*)Pagetable[i]) - DIRECT_REGION);
+        Pagetable[i] |= (PAGE_PRESENT | PAGE_RW);
+        //SerialPrintf("%d", i - 256);
+    }
+
+    SerialPrintf("[  Mem] Identity mapping higher half complete.\n");
+
+    MMapEnt* TopEntry = (MMapEnt*)(((&bootldr) + bootldr.size) - sizeof(MMapEnt));
+    size_t LargestAddress = TopEntry->ptr + TopEntry->size;
+
+    SerialPrintf("[  Mem] About to map lower memory into the Direct Region.\n");
+    for(size_t Address = 0; Address < AlignUpwards(LargestAddress, PAGE_SIZE); Address += PAGE_SIZE) {
+        MapVirtualMemory(&KernelAddressSpace, (size_t*)(((char*)Address) + DIRECT_REGION), Address, MAP_WRITE);
+    }
+    SerialPrintf("[  Mem] Lower half mapping complete.\n");
+
+    SerialPrintf("[  Mem] Mapping kernel into new memory map.\r\n");
+
+    //TODO: Disallow execution of rodata and data, and bootldr/environment
+    for(void* Address = CAST(void*, KERNEL_REGION);
+            Address < CAST(void*, KERNEL_REGION + 0x2000); // Lower half of Kernel
+            Address = CAST(void*, CAST(char*, Address) + PAGE_SIZE)) {
+                MapVirtualMemory(&KernelAddressSpace, Address, (CAST(size_t, Address) - KERNEL_REGION) + KERNEL_PHYSICAL, MAP_EXEC);
+    }
+
+    for(void* Address = CAST(void*, KERNEL_REGION + 0x2000);
+            Address < CAST(void*, KERNEL_REGION + 0x12000); // Higher half of kernel
+            Address = CAST(void*, CAST(char*, Address) + PAGE_SIZE)) {
+                MapVirtualMemory(&KernelAddressSpace, Address, (CAST(size_t, Address) - KERNEL_REGION) + KERNEL_PHYSICAL_2, MAP_EXEC);
+    }
+
+    for(void* Address = CAST(void*, FB_REGION);
+            Address < CAST(void*, 0x200000);     // TODO: Turn this into a calculation with bootldr.fb_size
+            Address = CAST(void*, CAST(char*, Address) + PAGE_SIZE)) {
+                MapVirtualMemory(&KernelAddressSpace, Address, (CAST(size_t, Address) - FB_REGION) + FB_PHYSICAL, MAP_WRITE);
+    }
+
+    SerialPrintf("[  Mem] Kernel mapped into pagetables. New PML4 at 0x%p\r\n", KernelAddressSpace.PML4);
+    //ASSERT(Allocator != NULL);
+}
+
+static size_t GetCachingAttribute(pagecache_t Cache) {
+    switch (Cache) {
+        case CACHE_WRITE_BACK: return 0;
+        case CACHE_WRITE_THROUGH: return 1 << 2;
+        case CACHE_NONE: return 1 << 3;
+        case CACHE_WRITE_COMBINING: return 1 << 6;
+    }
+
+    return 1 << 3;
+}
+
+static bool ExpandAllocator(size_t NewSize) {
+    size_t AllocSize = AlignUpwards(AllocatorPoolOverhead() + sizeof(size_t) * 5 + NewSize, PAGE_SIZE);
+    void* Pool = PhysAllocateMem(AllocSize);
+    return AddPoolToAllocator(Allocator, Pool, AllocSize) != NULL;
+} 
+
+static void GetPageFromTables(address_space_t* AddressSpace, size_t VirtualAddress, size_t** Page) {
+
+    //ASSERT(Page != NULL);
+    //ASSERT(AddressSpace != NULL);
+
+    size_t* Pagetable = AddressSpace->PML4;
+    for(int Level = 4; Level > 1; Level--) {
+        size_t* Entry = &Pagetable[(VirtualAddress >> (12u + 9u * (Level - 1))) & 0x1FFU];
+
+        ASSERT(*Entry & PAGE_PRESENT, "Page not present during retrieval");
+
+        Pagetable = (size_t*)((char*)(*Entry & 0x7ffffffffffff000ull) + DIRECT_REGION);
+    }
+
+    ASSERT(Pagetable[(VirtualAddress >> 12U) & 0x1FFU] & PAGE_PRESENT, "PDPE not present during retrieval");
+    *Page = &Pagetable[(VirtualAddress >> 12U) & 0x1FFU];
+
+}
+
+void SetAddressSpace(address_space_t* AddressSpace) {
+    //ASSERT(AddressSpace != NULL);
+
+    if((size_t)((char*)ReadControlRegister(3) + DIRECT_REGION) != (size_t) &AddressSpace->PML4) {
+        WriteControlRegister(3, CAST(size_t, &AddressSpace->PML4));
+    }
+}
+
+void MapVirtualMemory(address_space_t* AddressSpace, void* VirtualAddress, size_t PhysicalAddress, mapflags_t Flag) {
+
+    //bool MapGlobally = false;
+    size_t Virtual = (size_t)VirtualAddress;
+
+    //ASSERT(AddressSpace != NULL);
+    TicketAttemptLock(&AddressSpace->Lock);
+
+    size_t Flags = PAGE_PRESENT;
+
+    if(Flag & MAP_WRITE)
+        Flags |= MAP_WRITE;
+    
+    if(Virtual < USER_REGION)
+        Flags |= PAGE_USER;
+    //TODO: Global mapping
+
+    size_t* Pagetable = AddressSpace->PML4;
+    for(int Level = 4; Level > 1; Level--) {
+        size_t* Entry = &Pagetable[(Virtual >> (12u + 9u * (Level - 1))) & 0x1FFu];
+
+        if(!(*Entry & PAGE_PRESENT)) {
+            directptr_t Pointer = PhysAllocateZeroMem(PAGE_SIZE);
+            *Entry = (size_t)(((char*)Pointer) + DIRECT_REGION);
+        }
+
+        *Entry |= Flags;
+
+        Pagetable = (size_t*)(((char*)(*Entry & 0x7ffffffffffff000ull) + DIRECT_REGION));
+    }
+
+    size_t* Entry = &Pagetable[(Virtual >> 12u) & 0x1FFu];
+    *Entry = Flags | PhysicalAddress;
+    
+
+    if(AddressSpace != NULL) {
+        TicketUnlock(&AddressSpace->Lock);
+    }
+
+}
+
+void UnmapVirtualMemory(address_space_t* AddressSpace, void* VirtualAddress){ 
+    //ASSERT(AddressSpace != NULL);
+
+    TicketAttemptLock(&AddressSpace->Lock);
+
+    size_t* Entry;
+    GetPageFromTables(AddressSpace, (size_t)VirtualAddress, &Entry);
+
+    *Entry = 0;
+    InvalidatePage((size_t)VirtualAddress);
+
+    if(AddressSpace != NULL) {
+        TicketUnlock(&AddressSpace->Lock);
+    }
+
+}
+
+void CacheVirtualMemory(address_space_t* AddressSpace, void* VirtualAddress, pagecache_t Cache) {
+
+    //ASSERT(AddressSpace != NULL);
+
+    TicketAttemptLock(&AddressSpace->Lock);
+
+    size_t* Entry;
+
+    GetPageFromTables(AddressSpace, (size_t)VirtualAddress, &Entry);
+
+    *Entry &= ~((1 << 6) | (1 << 2) | (1 << 3));
+    *Entry |= GetCachingAttribute(Cache);
+
+    InvalidatePage((size_t)VirtualAddress);
+
+    if(AddressSpace != NULL) {
+        TicketUnlock(&AddressSpace->Lock);
+    }
+}
+
+
+void* AllocateMemory(size_t Bits) {
+    TicketAttemptLock(&AllocatorLock);
+
+    void* Result = AllocatorMalloc(Allocator, Bits);
+
+    if(Result == NULL) {
+        if(!ExpandAllocator(Bits)) {
+            TicketUnlock(&AllocatorLock);
+            return 0ULL;
+        }
+
+        Result = AllocatorMalloc(Allocator, Bits);
+    }
+
+    if(Result != NULL) {
+        memset(Result, 0, Bits);
+    }
+
+    TicketUnlock(&AllocatorLock);
+    return Result;
+
+}
+
+void* ReallocateMemory(void* Address, size_t NewSize) {
+    TicketAttemptLock(&AllocatorLock);
+    void* Result = AllocatorRealloc(Allocator, Address, NewSize);
+
+    if(Result == NULL) {
+        if(!ExpandAllocator(NewSize)) {
+            TicketUnlock(&AllocatorLock);
+            return 0ULL;
+        }
+
+        Result = AllocatorRealloc(Allocator, Address, NewSize);
+    }
+
+    TicketUnlock(&AllocatorLock);
+    return Result;
+    
+}
+
+void FreeMemory(void* Address) {
+    TicketAttemptLock(&AllocatorLock);
+    AllocatorFree(Allocator, Address);
+    TicketUnlock(&AllocatorLock);
+}
+
+void* AllocateKernelStack() {
+    void* StackAddress = NULL;
+    size_t StackSize = PAGE_SIZE * 4;
+
+    TicketAttemptLock(&StackLock);
+    if(ListIsEmpty(&StackFreeList)) {
+        StackAddress = StackPointer;
+        StackPointer = (void*)(((char*)StackPointer) +  (4*KiB) + StackSize);
+
+        for(size_t i = 0; i < (StackSize / PAGE_SIZE); i++) {
+            directptr_t NewStack;
+            NewStack = PhysAllocateZeroMem(PAGE_SIZE);
+            MapVirtualMemory(&KernelAddressSpace, (void*)((size_t)StackAddress + i * PAGE_SIZE), (size_t)((char*)NewStack) - DIRECT_REGION, MAP_WRITE);
+        }
+    } else {
+        list_entry_t* StackEntry = StackFreeList.Next;
+        ListRemove(StackEntry);
+        memset(StackEntry, 0, StackSize);
+        StackAddress = (void*)StackEntry;
+    }
+
+    TicketUnlock(&StackLock);
+
+    StackAddress = (void*)((size_t)StackAddress + StackSize);
+    StackAddress = (void*)((size_t)StackAddress - sizeof(size_t) * 2);
+
+    return StackAddress;
+}
+
+void FreeKernelStack(void* StackAddress) {
+    TicketAttemptLock(&StackLock);
+    list_entry_t* ListEntry = (list_entry_t*)(((size_t)(StackAddress) + (sizeof(size_t) * 2)) - (PAGE_SIZE * 4));
+    ListAdd(&StackFreeList, ListEntry);
+    TicketUnlock(&StackLock);
+}