Add Exception handling

README.md

@@ -29,11 +29,11 @@ The kernel is based on [the bare bones kernel from the OSDev wiki](https://wiki.
 - [x] _Very_ basic memory management
 - [x] Interrupt handling
 - [x] Keyboard input
+- [x] Exception handling
 - [ ] Filesystem interaction
   - [ ] Show files in directory
   - [ ] Read files in directory
   - [ ] Write files in directory
-- [ ] Exception handling
 - [ ] Tests
 - [ ] Running executables from filesystem
 - [ ] Better memory management

kernel/exception.c

@@ -0,0 +1,71 @@
+#ifndef EXCEPTION_C
+#define EXCEPTION_C
+
+#include "terminal.c"
+
+typedef struct interrupt_frame_struct {
+    uint32_t eip;
+    uint32_t cs;
+    uint32_t eflags;
+} interrupt_frame;
+
+#define EXCEPTION_HANDLER_NO_ERR(NAME, STR) \
+__attribute__((interrupt)) void NAME (interrupt_frame* frame) { \
+    outb(0x20, 0x20); \
+    bsod(frame, STR, -1); \
+}
+
+#define EXCEPTION_HANDLER_ERR(NAME, STR) \
+__attribute__((interrupt)) void NAME (interrupt_frame* frame, uint32_t err_code) { \
+    outb(0x20, 0x20); \
+    bsod(frame, STR, err_code); \
+}
+
+void bsod(interrupt_frame* frame, char* err_msg, int32_t err_code) {
+
+    terminal_initialize();
+    terminal_writestring("An exception occured: ");
+    terminal_writestring(err_msg);
+    if(err_code != -1) {
+        terminal_writestring(" (error code = 0x");
+        terminal_writeint(err_code, 16);
+        terminal_writestring(")");
+    }
+    terminal_writestring("\nHere's what we know:\n");
+    terminal_writestring("eip = 0x");
+    terminal_writeint(frame->eip, 16);
+    terminal_writestring("\ncs = 0x");
+    terminal_writeint(frame->cs, 16);
+    terminal_writestring("\neflags = 0b");
+    terminal_writeint(frame->eflags, 2);
+
+
+    for(;;) {
+        asm("hlt");
+    }
+}
+
+EXCEPTION_HANDLER_NO_ERR(divide_by_zero_handler, "Divide by zero")
+EXCEPTION_HANDLER_NO_ERR(debug_handler, "debug")
+EXCEPTION_HANDLER_NO_ERR(non_maskable_interrupt_handler, "Non maskable interrupt")
+EXCEPTION_HANDLER_NO_ERR(breakpoint_handler, "Breakpoint")
+EXCEPTION_HANDLER_NO_ERR(overflow_handler, "Overflow")
+EXCEPTION_HANDLER_NO_ERR(bound_range_exceeded_handler, "Bound range exceeded")
+EXCEPTION_HANDLER_NO_ERR(invalid_opcode_handler, "Invalid opcode")
+EXCEPTION_HANDLER_NO_ERR(device_not_available_handler, "Device not available")
+EXCEPTION_HANDLER_ERR(double_fault_handler, "Double fault")
+EXCEPTION_HANDLER_NO_ERR(coprocessor_seg_overrun_handler, "Coprocessor seg overrun")
+EXCEPTION_HANDLER_ERR(invalid_tss_handler, "Invalid tss")
+EXCEPTION_HANDLER_ERR(segment_not_present_handler, "Segment not present")
+EXCEPTION_HANDLER_ERR(stack_segment_fault_handler, "Stack segment fault")
+EXCEPTION_HANDLER_ERR(general_protection_fault_handler, "General protection fault")
+EXCEPTION_HANDLER_ERR(page_fault_handler, "Page fault")
+EXCEPTION_HANDLER_NO_ERR(reserved_handler, "Reserved")
+EXCEPTION_HANDLER_NO_ERR(x87_fp_exception_handler, "x87 floating point exception")
+EXCEPTION_HANDLER_NO_ERR(alignment_check_handler, "Alignment check");
+EXCEPTION_HANDLER_NO_ERR(machine_check_handler, "Machine check");
+EXCEPTION_HANDLER_NO_ERR(simd_fp_exception_handler, "SIMD floating point exception");
+EXCEPTION_HANDLER_NO_ERR(virtualization_exception_handler, "Virtualization exception");
+EXCEPTION_HANDLER_NO_ERR(security_exception_handler, "Security exception");
+
+#endif //EXCEPTION_C

kernel/exception_list.c

@@ -0,0 +1,34 @@
+typedef enum exception_enum {
+    DIVIDE_BY_ZERO              = 0,
+    DEBUG                       = 1,
+    NON_MASKABLE_INTERRUPT      = 2,
+    BREAKPOINT                  = 3,
+    OVERFLOW                    = 4,
+    BOUND_RANGE_EXCEEDED        = 5,
+    INVALID_OPCODE              = 6,
+    DEVICE_NOT_AVAILABLE        = 7,
+    DOUBLE_FAULT                = 8, // Error code = 0
+    COPROCESSOR_SEG_OVERRUN     = 9,
+    INVALID_TSS                 = 10, // Error code = (invalid selector index)
+    SEGMENT_NOT_PRESENT         = 11, // Error code = (segment selector index)
+    STACK_SEGMENT_FAULT         = 12, // Error code = (segment selector index) if invalid ssi, otherwise 0
+    GENERAL_PROTECTION_FAULT    = 13, // Error code = (segment selector index) if invalid ssi, otherwise 0
+    PAGE_FAULT                  = 14, // Error code = bitmap, see https://wiki.osdev.org/Exceptions#Page_Fault
+    RESERVED_15                 = 15,
+    X87_FP_EXCEPTION            = 16,
+    ALIGNMENT_CHECK             = 17,
+    MACHINE_CHECK               = 18,
+    SIMD_FP_EXCEPTION           = 19,
+    VIRTUALIZATION_EXCEPTION    = 20,
+    RESERVED_21                 = 21,
+    RESERVED_22                 = 22,
+    RESERVED_23                 = 23,
+    RESERVED_24                 = 24,
+    RESERVED_25                 = 25,
+    RESERVED_26                 = 26,
+    RESERVED_27                 = 27,
+    RESERVED_28                 = 28,
+    RESERVED_29                 = 29,
+    SECURITY_EXCEPTION          = 30,
+    RESERVED_31                 = 31
+} exception;

kernel/interrupts.c

@@ -7,6 +7,8 @@
 #include "memory.c"
 #include "terminal.c"
 #include "inline_asm.c"
+#include "exception.c"
+#include "exception_list.c"
 #include "drivers/keyboard/keyboard.c"
 
 typedef struct idt_entry_struct {
@@ -17,28 +19,9 @@ typedef struct idt_entry_struct {
    uint16_t offset_2; // offset bits 16..31
 } idt_entry;
 
-struct interrupt_frame {
-    uint32_t esp;
-    uint32_t ss;
-    uint32_t gs;
-    uint32_t fs;
-    uint32_t es;
-    uint32_t ds;
-    uint32_t ebp;
-    uint32_t edi;
-    uint32_t esi;
-    uint32_t edx;
-    uint32_t ecx;
-    uint32_t ebx;
-    uint32_t eax;
-    uint32_t eip;
-    uint32_t cs;
-    uint32_t eflags;
-};
-
 idt_entry IDT[256];
 
-void interrupt_new_handler(int intnum, void (*handler)(struct interrupt_frame*)) {
+void interrupt_new_handler(int intnum, void (*handler)(interrupt_frame*)) {
     uint32_t handler_address = (uint32_t) handler;
     IDT[intnum].offset_1 = (uint16_t) (handler_address & 0xffff);
     IDT[intnum].selector = 0x08;
@@ -68,6 +51,40 @@ void interrupt_init() {
 	outb(0x21 , 0xff);
 	outb(0xA1 , 0xff);
 
+    // Exceptions
+    interrupt_new_handler(DIVIDE_BY_ZERO,           divide_by_zero_handler);
+    interrupt_new_handler(DEBUG,                    debug_handler);
+    interrupt_new_handler(NON_MASKABLE_INTERRUPT,   non_maskable_interrupt_handler);
+    interrupt_new_handler(BREAKPOINT,               breakpoint_handler);
+    interrupt_new_handler(OVERFLOW,                 overflow_handler);
+    interrupt_new_handler(BOUND_RANGE_EXCEEDED,     bound_range_exceeded_handler);
+    interrupt_new_handler(INVALID_OPCODE,           invalid_opcode_handler);
+    interrupt_new_handler(DEVICE_NOT_AVAILABLE,     device_not_available_handler);
+    interrupt_new_handler(DOUBLE_FAULT,             double_fault_handler);
+    interrupt_new_handler(COPROCESSOR_SEG_OVERRUN,  coprocessor_seg_overrun_handler);
+    interrupt_new_handler(INVALID_TSS,              invalid_tss_handler);
+    interrupt_new_handler(SEGMENT_NOT_PRESENT,      segment_not_present_handler);
+    interrupt_new_handler(STACK_SEGMENT_FAULT,      stack_segment_fault_handler);
+    interrupt_new_handler(GENERAL_PROTECTION_FAULT, general_protection_fault_handler);
+    interrupt_new_handler(PAGE_FAULT,               page_fault_handler);
+    interrupt_new_handler(RESERVED_15,              reserved_handler);
+    interrupt_new_handler(X87_FP_EXCEPTION,         x87_fp_exception_handler);
+    interrupt_new_handler(ALIGNMENT_CHECK,          alignment_check_handler);
+    interrupt_new_handler(MACHINE_CHECK,            machine_check_handler);
+    interrupt_new_handler(SIMD_FP_EXCEPTION,        simd_fp_exception_handler);
+    interrupt_new_handler(VIRTUALIZATION_EXCEPTION, virtualization_exception_handler);
+    interrupt_new_handler(RESERVED_21,              reserved_handler);
+    interrupt_new_handler(RESERVED_22,              reserved_handler);
+    interrupt_new_handler(RESERVED_23,              reserved_handler);
+    interrupt_new_handler(RESERVED_24,              reserved_handler);
+    interrupt_new_handler(RESERVED_25,              reserved_handler);
+    interrupt_new_handler(RESERVED_26,              reserved_handler);
+    interrupt_new_handler(RESERVED_27,              reserved_handler);
+    interrupt_new_handler(RESERVED_28,              reserved_handler);
+    interrupt_new_handler(RESERVED_29,              reserved_handler);
+    interrupt_new_handler(SECURITY_EXCEPTION,       security_exception_handler);
+    interrupt_new_handler(RESERVED_31,              reserved_handler);
+
     interrupt_new_handler(0x21, keyboard_handler);
 
     uint16_t size = (sizeof(idt_entry) * 256);

kernel/terminal.c

@@ -94,7 +94,7 @@ void terminal_writestring(const char* data) {
 	terminal_write(data, strlen(data));
 }
 
-char* itoa(int value, char* result, int base) {
+char* itoa(unsigned int value, char* result, int base) {
 	// check that the base if valid
 	if (base < 2 || base > 36) { *result = '\0'; return result; }
 
@@ -107,8 +107,6 @@ char* itoa(int value, char* result, int base) {
 		*ptr++ = "zyxwvutsrqponmlkjihgfedcba9876543210123456789abcdefghijklmnopqrstuvwxyz" [35 + (tmp_value - value * base)];
 	} while ( value );
 
-	// Apply negative sign
-	if (tmp_value < 0) *ptr++ = '-';
 	*ptr-- = '\0';
 	while(ptr1 < ptr) {
 		tmp_char = *ptr;
@@ -118,4 +116,10 @@ char* itoa(int value, char* result, int base) {
 	return result;
 }
 
+void terminal_writeint(int number, int base) {
+	char* result = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX";
+	itoa(number, result, base);
+	terminal_writestring(result);
+}
+
 #endif //TERMINAL_C