Fixes for memory. Lots of work left.

Mainly, we need to be able to locate the kernel executable physically in memory.

chroma/inc/kernel/boot/boot.h

@@ -14,7 +14,8 @@ extern "C" {
 #define BOOT_MAGIC "BOOT"
 
 /* minimum protocol level:
- *  hardcoded kernel name, static kernel memory addresses */
+ *  hardcoded kernel name, static kernel memory addresses 
+ * this is the default */
 #define PROTOCOL_MINIMAL 0
 /* static protocol level:
  *  kernel name parsed from environment, static kernel memory addresses */
@@ -27,6 +28,7 @@ extern "C" {
 
 /* loader types, just informational */
 #define LOADER_BIOS (0<<2)
+/* unless we get to a weird stage, these should never be used. */
 #define LOADER_UEFI (1<<2)
 #define LOADER_RPI  (2<<2)
 
@@ -106,6 +108,31 @@ 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
 }
 #endif

chroma/inc/kernel/chroma.h

@@ -28,6 +28,7 @@ extern bootinfo bootldr;
 extern unsigned char* environment;
 extern uint8_t fb;
 extern volatile unsigned char _binary_font_psf_start;
+extern volatile size_t* _kernel_text_start;
 
 extern address_space_t KernelAddressSpace;
 

chroma/inc/kernel/system/memory.h

@@ -8,6 +8,8 @@
  ***     Chroma       ***
  ***********************/
 
+size_t KernelLocation;
+
 
 /************************************************
 *    C O N S T A N T S   A N D   M A C R O S
@@ -52,6 +54,8 @@
 #define ERR_RESERVED 0x8
 #define ERR_INST     0x10
 
+#define ELF64MAGIC 0x7F454c46
+
 
 /*
  * The way we boot, using BOOTBOOT, and the static hard drive images, means 
@@ -104,8 +108,6 @@
 #define FB_REGION           0xFFFFFFFFFC000000ull // Cannot move!
 #define FB_PHYSICAL         0x00000000E0000000ull // Physical location of the Framebuffer
 #define KERNEL_REGION       0xFFFFFFFFFFE00000ull // -2MiB, from bootloader
-#define KERNEL_PHYSICAL     0x0000000000008000ull // Physical location of the kernel
-#define KERNEL_PHYSICAL_2   0x000000000011C000ull // For some reason the kernel is split in half
 
 #define USER_REGION         0x00007FFFFFFFFFFFull // Not needed yet, but we're higher half so we might as well be thorough
 

chroma/kernel.c

@@ -20,9 +20,48 @@ 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] Searching for kernel... Constants start at 0x%p\r\n", &_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 = 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/memory/paging.c

@@ -48,7 +48,7 @@
  * 
  */ 
 
-extern size_t _kernel_text_start;
+//extern size_t _kernel_text_start;
 extern size_t _kernel_rodata_start;
 extern size_t _kernel_data_start;
 
@@ -138,10 +138,10 @@ void InitPaging() {
 
     SerialPrintf("[  Mem] Identity mapping higher half complete.\n");
 
-    MMapEnt* TopEntry = (MMapEnt*)(((&bootldr) + bootldr.size) - sizeof(MMapEnt));
+    MMapEnt* TopEntry = (MMapEnt*)(((size_t) (&bootldr) + bootldr.size) - sizeof(MMapEnt));
     size_t LargestAddress = TopEntry->ptr + TopEntry->size;
 
-    SerialPrintf("[  Mem] About to map lower memory into the Direct Region.\n");
+    SerialPrintf("[  Mem] About to map lower memory into the Direct Region. Highest address = 0x%p\n", AlignUpwards(LargestAddress, PAGE_SIZE));
     for(size_t Address = 0; Address < AlignUpwards(LargestAddress, PAGE_SIZE); Address += PAGE_SIZE) {
         MapVirtualMemory(&KernelAddressSpace, (size_t*)(((char*)Address) + DIRECT_REGION), Address, MAP_WRITE);
     }
@@ -151,16 +151,16 @@ void InitPaging() {
 
     //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*, KERNEL_REGION + (KernelEnd - KernelAddr)); // 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);
+                MapVirtualMemory(&KernelAddressSpace, Address, (CAST(size_t, Address) - KERNEL_REGION) + KernelLocation, MAP_EXEC);
     }
 
-    for(void* Address = CAST(void*, KERNEL_REGION + 0x2000);
+    /*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
@@ -169,6 +169,9 @@ void InitPaging() {
     }
 
     SerialPrintf("[  Mem] Kernel mapped into pagetables. New PML4 at 0x%p\r\n", KernelAddressSpace.PML4);
+    SerialPrintf("[  Mem] About to move into our own pagetables.\r\n");
+    WriteControlRegister(3, (size_t) KernelAddressSpace.PML4);
+    SerialPrintf("[  Mem] We survived!\r\n");
     //ASSERT(Allocator != NULL);
 }