End of the day cleanup.

* Added symbol files to .gitignore
* Improved text in #PG and #GP handlers
* Added the printing of the multiboot structure address and the magic value
* Added page fault screenshot to readme

.gitignore

@@ -5,4 +5,6 @@ isodir/
 root/
 *.iso
 *.img
+*.sym
+
 

Makefile

@@ -37,6 +37,7 @@ run: all
 	$(EMULATOR) -cdrom build/barinkOS.iso -serial stdio -vga std -display gtk -m 2G -cpu core2duo
 
 debug: all
+	objcopy --only-keep-debug build/myos.bin kernel.sym
 	$(EMULATOR) -cdrom build/barinkOS.iso -serial stdio -vga std -display gtk -m 2G -cpu core2duo -s -d int
 
 build_kernel: $(OBJ_LINK_LIST)

README.md

@@ -16,6 +16,11 @@ W.I.P - Working on interrupt handling
 
 ![Multiboot integration](screenshots/multiboot.png) \
 Multiboot information can be read by the kernel.
+
+![Page faulting](screenshots/PageFault.png) \
+Enabled paging and am getting page faults!
+
+
 ________________________
 
 ### The goal

src/kernel/Interrupts/idt/idt.cpp

@@ -1,10 +1,11 @@
 #include "idt.h"
 #include "../../Drivers/PIT/pit.h"
 #include "../../Drivers/PS-2/keyboard.h"
-
+#include "../../cpu.h"
 IDT_entry idt_table[256];
 IDT_ptr idt_ptr;
 
+
 void set_id_entry (uint8_t num , uint32_t base, uint16_t sel,  uint8_t flags){
     idt_table[num].offset_1 = base & 0xFFFF;
     idt_table[num].selector = sel;
@@ -15,7 +16,7 @@ void set_id_entry (uint8_t num , uint32_t base, uint16_t sel,  uint8_t flags){
 };
 
 void irs_handler (registers regs) {
-     
+     uint32_t FaultingAddress;
         //printf("(IRS) Interrupt number: %d \r", regs.int_no);
         switch (regs.int_no)
         {
@@ -120,28 +121,81 @@ void irs_handler (registers regs) {
         case 13:
             // General Protection Exception #GP
             printf("#GP\n");
-            printf("EIP: 0x%x\n", regs.eip);
+
-            printf("EAX: 0x%x\n", regs.eax);
+            printf("Accessing memory caused a general protectuion exception.\n");
-            printf("EBP: 0x%x\n", regs.ebp);
+            
+            printf("Fault due to entry at index: %d", (regs.err_code >> 3 & 0xFFF ) );
+
+            if(regs.err_code & 0x3 >> 1 == 0   ){
+                printf("* Index references GDT");
+            }
+            if(regs.err_code & 0x3 >> 1 == 1  ){
+                printf("* Index references IDT");
+            }
+
+            if(regs.err_code & 0x3 >> 1 == 2   ){
+                printf("* Index references LDT");
+            }
+
+            if(regs.err_code & 0x3 >> 1 == 4  ){
+                printf("* Index references IDT");
+            }
+
+            if( regs.err_code & 0x1)
+            {
+                printf("* Originated externally!");
+            }
+
+            __asm__("cli;" "1: hlt;" "jmp 1b;");
+
         break;
         
         case 14:
             // Page Fault Exception #PF
             printf("#PF\n");
 
-            printf("EIP: 0x%x\n", regs.eip); // Points to faulting instruction ???
+            FaultingAddress = GetCR2();
-            printf("EAX: 0x%x\n", regs.eax); 
+            printf("Accessing the linear address 0x%x resulted in a page fault!\n\n", FaultingAddress);
-            printf("EBP: 0x%x\n", regs.ebp); // Base pointer pointing to the bottom of the stack 
+        
- 
-
             // Error code of 32 bits are on the stack
-            // CR2 register contains the 32-bit linear address that generated the exception
+            // CR2 register contains the 32-bit linear virtual address that generated the exception
             // See Intel Software Developers manual Volume 3A Part 1 page 236 for more info
-                   
+            #define PF_ERR_PRESENT_BIT 0x1
+            #define PF_ERR_WRITE_BIT 0x2
+            #define PF_ERR_USER_BIT 0x3
+            #define PF_ERR_RESERVERD_WRITE_BIT 0x4
+            #define PF_ERR_INSTRUCTION_FETCH_BIT 0x5
+            #define PF_ERR_PROTECTION_KEY_BIT 0x6
+            #define PF_ERR_SHADOW_STACK_BIT 0x7
+            #define PF_ERR_SOFTWARE_GUARD_EXTENSION_BIT 0xE
+
+            printf("REASON: \n\n");
+
+         
+            if (regs.err_code & PF_ERR_PRESENT_BIT ){
+                printf("* Page protection violation!\n");
+            } else{
+                printf("* Page not-present!\n");
+            }
+
+            if(regs.err_code & PF_ERR_WRITE_BIT){
+                printf("* Write access violation!\n");
+            } else{
+                printf("* Read access violation!\n");
+            }
+
+            if(regs.err_code & PF_ERR_USER_BIT){
+                printf("* Violation from user-space (CPL=3)\n");
+            }
+
+            if(regs.err_code & PF_ERR_INSTRUCTION_FETCH_BIT){
+                printf("* Caused by an instruction fetch. \n");
+            }
 
             /*
                 Check the error code to figure out what happened here
             */
+            __asm__("cli;" "1: hlt;" "jmp 1b;");
 
 
             

src/kernel/Memory/memory.cpp

@@ -10,7 +10,7 @@ void PhysicalMemory::setup( MemoryInfo* memory) {
 
     used_blocks = 0;
 
-    memoryBitMap = (uint32_t*) 0x00a00000;
+    memoryBitMap = (uint32_t*) 0xCCA00000;
 
 
     printf("Maximum Number of blocks: 0x%x, Number of bytes for memMap: 0x%x\n", max_blocks , (max_blocks/8));

src/kernel/cpu.h

@@ -60,3 +60,15 @@ extern "C" uint32_t GetCR4();
 
 #define GET_PSE_BIT(CONTROL_REGISTER_4) (CONTROL_REGISTER_4&0x4)
 #define GET_PAE_BIT(CONTROL_REGISTER_4) (CONTROL_REGISTER_4&0x5)
+
+/*
+*       CONTROL_REGISTER_2 FUNCTIONS
+*/
+
+extern "C" uint32_t GetCR2();
+
+/*
+*       CONTROL_REGISTER_3 FUNCTIONS
+*/
+
+extern "C" uint32_t GetCR3();

src/kernel/cpu.s

@@ -36,4 +36,28 @@ GetEFLAGS:
 
 	mov %ebp, %esp
 	pop %ebp
-	ret
+	ret
+
+.globl GetCR2
+GetCR2:
+	push %ebp
+	mov %esp, %ebp
+
+	xor %eax, %eax
+	mov %cr2, %eax
+	
+	mov %ebp, %esp
+	pop %ebp
+	ret
+	
+.globl GetCR3
+GetCR3:
+	push %ebp
+	mov %esp, %ebp
+
+	xor %eax, %eax
+	mov %cr3, %eax
+	
+	mov %ebp, %esp
+	pop %ebp
+	ret

src/kernel/kernel.cpp

@@ -2,8 +2,7 @@
 
 
 extern "C" void kernel_main (BootInfo* bootinfo) {
-    init_serial();
+    pit_initialise();
-    //pit_initialise();
 
     startSuperVisorTerminal(bootinfo);
 }   
@@ -17,9 +16,40 @@ extern "C" void early_main(unsigned long magic, unsigned long addr){
     initGDT();
     kterm_init();
     init_serial();
-    print_serial("Hello Higher half kernel!");
+    print_serial("Hello Higher half kernel!\n");
-    printf("DDDDDDDDDDDDDDDD");
+ 
-    return;
+    init_idt();
+    // Enable interrupts
+    asm volatile("STI");
+    
+    // map the multiboot structure into virtual memory 
+    // so we can gather the necessary data from it.
+   /* const uint32_t KERNEL_BASE_ADDR = 0xC0000000;
+    
+    uint32_t pageDirectoryIndex = (addr + KERNEL_BASE_ADDR)  >> 22;
+    printf("pageDirectoryIndex: %d\n", pageDirectoryIndex);
+
+    uint32_t pageTableIndex = (addr + KERNEL_BASE_ADDR >> 12)  & 0x1FFF;
+    printf("PagTableIndex: %d\n", pageTableIndex);
+
+    printf("boot_page_directory addr: 0x%x\n", &boot_page_directory);
+    printf("boot_page_table addr: 0x%x\n", &boot_page_table);
+
+    uint32_t* pageDirectoryEntry = (uint32_t*) ((uint32_t) &boot_page_directory) +  (pageDirectoryIndex * 4);
+    printf("page_directory_entry addr: 0x%x\n",  pageDirectoryEntry);
+
+    *pageDirectoryEntry  = ( addr & 0xFFFFF000 ) | 0x003;
+
+    uint32_t* page_table_entry = (uint32_t*) ((uint32_t) &boot_page_table)  + ( pageTableIndex * 4);
+    printf("page_table_entry addr: 0x%x\n" , page_table_entry);
+
+    *page_table_entry =  addr | 0x003;
+    
+    // Reload CR3 to force a flush
+    asm("movl %cr3, %ecx;" "movl %ecx, %cr3" );
+    */
+
+    printf("DEBUG:\n Magic: 0x%x\n MBT_addr: 0x%x\n", magic, addr);
     /**
      * Check Multiboot magic number
      * NOTE: Printf call should not be a thing this early on ...
@@ -33,13 +63,12 @@ extern "C" void early_main(unsigned long magic, unsigned long addr){
      * Show a little banner for cuteness
      */
     printf("|===    BarinkOS       ===|\n");
-    printf("Kernel Begin AT(0x%x)", kernel_begin);
+    const uint32_t KERNEL_BASE_ADDR = 0xC0000000;
-
     /**
      * Use the address given as an argument as the pointer
      * to a Multiboot information structure.
      */
-        multiboot_info_t* mbt = (multiboot_info_t*) addr;
+        multiboot_info_t* mbt = (multiboot_info_t*) (addr + KERNEL_BASE_ADDR);
 
     /**
      * Construct our own bootInfo structure
@@ -111,16 +140,11 @@ extern "C" void early_main(unsigned long magic, unsigned long addr){
         //InitializePaging();
         //IdentityMap();
         //Enable();
+    } else{
+        printf("memory flag not set!");
     }
     
-    //initGDT();
+    CheckMBT(  (multiboot_info_t *) addr);
-    //init_idt();
-    // Enable interrupts
-    //asm volatile("STI");
-    
-
-    //CheckMBT(  (multiboot_info_t *) addr);
-
 
     kernel_main(&bootinfo);
     

src/kernel/kernel.h

@@ -28,7 +28,7 @@ extern "C"
 #include "time.h"
 #include "SuperVisorTerminal/superVisorTerminal.h"
 
-#define CHECK_FLAG(flags, bit) ((flags) & (1 <<(bit)))
+#define CHECK_FLAG(flag, bit) ( flag & (1 << bit ))
 #define PANIC(message) {return;}