1 files changed, 253 insertions, 0 deletions
diff --git a/src/kernel/core/idt.c b/src/kernel/core/idt.c
new file mode 100644
index 0000000..2f244e3
--- /dev/null
+++ b/src/kernel/core/idt.c
@@ -0,0 +1,253 @@
+#include <idt.h>
+#include <gdt.h>
+#include <sys.h>
+#include <string.h>
+#include <dbglog.h>
+
+struct idt_entry {
+	uint16_t base_lo;		//Low part of address to jump to
+	uint16_t sel;			//Kernel segment selector
+	uint8_t always0;
+	uint8_t type_attr;			//Type
+	uint16_t base_hi;		//High part of address to jump to
+} __attribute__((packed));
+typedef struct idt_entry idt_entry_t;
+
+struct idt_ptr {
+	uint16_t limit;
+	uint32_t base;
+} __attribute__((packed));
+typedef struct idt_ptr idt_ptr_t;
+
+#define GATE_TYPE_INTERRUPT 14		// IF is cleared on interrupt
+#define GATE_TYPE_TRAP 15			// IF stays as is
+
+#define GATE_PRESENT (1<<7)
+#define GATE_DPL_SHIFT 5
+
+
+void isr0();
+void isr1();
+void isr2();
+void isr3();
+void isr4();
+void isr5();
+void isr6();
+void isr7();
+void isr8();
+void isr9();
+void isr10();
+void isr11();
+void isr12();
+void isr13();
+void isr14();
+void isr15();
+void isr16();
+void isr17();
+void isr18();
+void isr19();
+void isr20();
+void isr21();
+void isr22();
+void isr23();
+void isr24();
+void isr25();
+void isr26();
+void isr27();
+void isr28();
+void isr29();
+void isr30();
+void isr31();
+
+void irq0();
+void irq1();
+void irq2();
+void irq3();
+void irq4();
+void irq5();
+void irq6();
+void irq7();
+void irq8();
+void irq9();
+void irq10();
+void irq11();
+void irq12();
+void irq13();
+void irq14();
+void irq15();
+
+void syscall64();
+
+// ************************************************************
+// Handler code
+
+static idt_entry_t idt_entries[256];
+static idt_ptr_t idt_ptr;
+
+static isr_handler_t irq_handlers[16] = {0};
+static isr_handler_t ex_handlers[32] = {0};
+
+/*	Called in interrupt.s when an exception fires (interrupt 0 to 31) */
+void idt_exHandler(registers_t *regs) {
+	if (ex_handlers[regs->int_no] != 0) {
+		ex_handlers[regs->int_no](regs);
+	} else {
+		//TODO: make sure all exceptions happenning in userspace do not cause kernel panic...
+		dbg_printf("Unhandled exception: %i\n", regs->int_no);
+		dbg_dump_registers(regs);
+		PANIC("Unhandled exception");
+	}
+} 
+
+/*	Called in interrupt.s when an IRQ fires (interrupt 32 to 47) */
+void idt_irqHandler(registers_t *regs) {
+	if (regs->err_code > 7) {
+		outb(0xA0, 0x20);
+	}
+	outb(0x20, 0x20);
+
+	dbg_printf("IRQ %i\n", regs->err_code);
+	if (irq_handlers[regs->err_code] != 0) {
+		irq_handlers[regs->err_code](regs);
+	}
+}
+
+/* Caled in interrupt.s when a syscall is called */
+void idt_syscallHandler(registers_t *regs) {
+	dbg_printf("Syscall %i\n", regs->int_no);
+	// do nothing, yet.
+}
+
+/*	For internal use only. Sets up an entry of the IDT with given parameters. */
+static void idt_set_gate(uint8_t num, void (*fun)(), uint8_t type) {
+	uint32_t base = (uint32_t)fun;
+
+	idt_entries[num].base_lo = base & 0xFFFF;
+	idt_entries[num].base_hi = (base >> 16) & 0xFFFF;
+
+	idt_entries[num].sel = K_CODE_SEGMENT;
+	idt_entries[num].always0 = 0;
+	idt_entries[num].type_attr = GATE_PRESENT
+				| (3 << GATE_DPL_SHIFT)		// accessible from user mode
+				| type;
+}
+
+static const struct {
+	uint8_t num;
+	void (*fun)();
+	uint8_t type;
+} gates[] = {
+	// Most processor exceptions are traps and handling them
+	// should be preemptible
+	{ 0,	isr0,	GATE_TYPE_TRAP },
+	{ 1,	isr1,	GATE_TYPE_TRAP },
+	{ 2,	isr2,	GATE_TYPE_TRAP },
+	{ 3,	isr3,	GATE_TYPE_TRAP },
+	{ 4,	isr4,	GATE_TYPE_TRAP },
+	{ 5,	isr5,	GATE_TYPE_TRAP },
+	{ 6,	isr6,	GATE_TYPE_TRAP },
+	{ 7,	isr7,	GATE_TYPE_TRAP },
+	{ 8,	isr8,	GATE_TYPE_TRAP },
+	{ 9,	isr9,	GATE_TYPE_TRAP },
+	{ 10,	isr10,	GATE_TYPE_TRAP },
+	{ 11,	isr11,	GATE_TYPE_TRAP },
+	{ 12,	isr12,	GATE_TYPE_TRAP },
+	{ 13,	isr13,	GATE_TYPE_TRAP },
+	{ 14,	isr14,	GATE_TYPE_INTERRUPT },	// reenables interrupts later on
+	{ 15,	isr15,	GATE_TYPE_TRAP },
+	{ 16,	isr16,	GATE_TYPE_TRAP },
+	{ 17,	isr17,	GATE_TYPE_TRAP },
+	{ 18,	isr18,	GATE_TYPE_TRAP },
+	{ 19,	isr19,	GATE_TYPE_TRAP },
+	{ 20,	isr20,	GATE_TYPE_TRAP },
+	{ 21,	isr21,	GATE_TYPE_TRAP },
+	{ 22,	isr22,	GATE_TYPE_TRAP },
+	{ 23,	isr23,	GATE_TYPE_TRAP },
+	{ 24,	isr24,	GATE_TYPE_TRAP },
+	{ 25,	isr25,	GATE_TYPE_TRAP },
+	{ 26,	isr26,	GATE_TYPE_TRAP },
+	{ 27,	isr27,	GATE_TYPE_TRAP },
+	{ 28,	isr28,	GATE_TYPE_TRAP },
+	{ 29,	isr29,	GATE_TYPE_TRAP },
+	{ 30,	isr30,	GATE_TYPE_TRAP },
+	{ 31,	isr31,	GATE_TYPE_TRAP },
+
+	// IRQs are not preemptible ; an IRQ handler should do the bare minimum
+	// (communication with the hardware), and then pass a message to a worker
+	// process in order to do further processing
+	{ 32,	irq0,	GATE_TYPE_INTERRUPT },
+	{ 33,	irq1,	GATE_TYPE_INTERRUPT },
+	{ 34,	irq2,	GATE_TYPE_INTERRUPT },
+	{ 35,	irq3,	GATE_TYPE_INTERRUPT },
+	{ 36,	irq4,	GATE_TYPE_INTERRUPT },
+	{ 37,	irq5,	GATE_TYPE_INTERRUPT },
+	{ 38,	irq6,	GATE_TYPE_INTERRUPT },
+	{ 39,	irq7,	GATE_TYPE_INTERRUPT },
+	{ 40,	irq8,	GATE_TYPE_INTERRUPT },
+	{ 41,	irq9,	GATE_TYPE_INTERRUPT },
+	{ 42,	irq10,	GATE_TYPE_INTERRUPT },
+	{ 43,	irq11,	GATE_TYPE_INTERRUPT },
+	{ 44,	irq12,	GATE_TYPE_INTERRUPT },
+	{ 45,	irq13,	GATE_TYPE_INTERRUPT },
+	{ 46,	irq14,	GATE_TYPE_INTERRUPT },
+	{ 47,	irq15,	GATE_TYPE_INTERRUPT },
+
+	// Of course, syscalls are preemptible
+	{ 64,	syscall64,	GATE_TYPE_TRAP },
+
+	{ 0, 0, 0 }
+};
+
+/*	Remaps the IRQs. Sets up the IDT. */
+void idt_init() {
+	memset((uint8_t*)&idt_entries, 0, sizeof(idt_entry_t) * 256);
+
+	//Remap the IRQ table
+	outb(0x20, 0x11);
+	outb(0xA0, 0x11);
+	outb(0x21, 0x20);
+	outb(0xA1, 0x28);
+	outb(0x21, 0x04);
+	outb(0xA1, 0x02);
+	outb(0x21, 0x01);
+	outb(0xA1, 0x01);
+	outb(0x21, 0x0);
+	outb(0xA1, 0x0);
+
+	for (int i = 0; gates[i].type != 0; i++) {
+		idt_set_gate(gates[i].num, gates[i].fun, gates[i].type);
+	}
+
+	idt_ptr.limit = (sizeof(idt_entry_t) * 256) - 1;
+	idt_ptr.base = (uint32_t)&idt_entries;
+
+	asm volatile ("lidt %0"::"m"(idt_ptr):"memory");
+	
+	// Some setup calls that come later on are not preemptible,
+	// so we wait until then to enable interrupts.
+}
+
+/*	Sets up an IRQ handler for given IRQ. */
+void idt_set_irq_handler(int number, isr_handler_t func) {
+	if (number < 16 && number >= 0) {
+		irq_handlers[number] = func;
+	}
+}
+
+/*	Sets up a handler for a processor exception */
+void idt_set_ex_handler(int number, isr_handler_t func) {
+	if (number >= 0 && number < 32) {
+		ex_handlers[number] = func;
+	}
+}
+
+void dbg_dump_registers(registers_t *regs) {
+	dbg_printf("/ Exception %i\n", regs->int_no);
+	dbg_printf("| EAX: 0x%p   EBX: 0x%p   ECX: 0x%p   EDX: 0x%p\n", regs->eax, regs->ebx, regs->ecx, regs->edx);
+	dbg_printf("| EDI: 0x%p   ESI: 0x%p   ESP: 0x%p   EBP: 0x%p\n", regs->edi, regs->esi, regs->esp, regs->ebp);
+	dbg_printf("| EIP: 0x%p   CS : 0x%p   DS : 0x%p   SS : 0x%p\n", regs->eip, regs->cs, regs->ds, regs->ss);
+	dbg_printf("\\ EFl: 0x%p   I# : 0x%p   Err: 0x%p\n", regs->eflags, regs->int_no, regs->err_code);
+}
+
+/* vim: set ts=4 sw=4 tw=0 noet :*/
+