1 files changed, 160 insertions, 0 deletions
diff --git a/src/arch/amd64/cpu/idt.c b/src/arch/amd64/cpu/idt.c
new file mode 100644
index 0000000..053f614
--- /dev/null
+++ b/src/arch/amd64/cpu/idt.c
@@ -0,0 +1,160 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <lib.h>
+#include <panic.h>
+#include "idt.h"
+#include "debugger.h"
+#include "../paging.h"
+#include "../drivers/pic.h"
+
+#define IDT_SIZE 256
+
+struct idt_entry {
+	uint16_t isr_low;    // low 16 bits of isr
+	uint16_t kernel_cs;  // kernel segment selector
+	uint8_t ist;         // interrupt stack table
+	uint8_t flags;       // gate type, privilege level, present bit
+	uint16_t isr_mid;    // middle 16 bits of isr
+	uint32_t isr_high;   // high 32 bits of isr
+	uint32_t reserved;
+} __attribute__((packed));
+
+struct idtr {
+	uint16_t size;
+	uint64_t address;
+} __attribute__((packed));
+
+// interrupt gate
+#define GATE_64BIT_INT  0x0E
+// trap gate
+#define GATE_64BIT_TRAP 0x0F
+
+// privilege ring allowed to call interrupt
+#define RING0 0x00
+#define RING1 0x20
+#define RING2 0x40
+#define RING3 0x60
+
+// interrupt is present in IDT
+#define PRESENT 0x80
+
+__attribute__((aligned(0x10)))
+static struct idt_entry idt[256];
+
+static struct idtr idtr;
+// from idt.S
+extern void *isr_stub_table[];
+
+// initialize and load the IDT
+void idt_init(void) {
+	// initialize idtr
+	idtr.address = (uint64_t)&idt;
+	idtr.size = (uint16_t)sizeof(struct idt_entry) * IDT_SIZE - 1;
+
+	// initialize idt
+	for (size_t vector = 0; vector < IDT_SIZE; vector++) {
+		struct idt_entry *entry = &idt[vector];
+
+		uint64_t isr = (uint64_t)isr_stub_table[vector];
+		// interrupts before 0x20 are for cpu exceptions
+		uint8_t gate_type = (vector < 0x20) ? GATE_64BIT_TRAP : GATE_64BIT_INT;
+
+		entry->kernel_cs = 0x08; // offset of 1 into GDT
+		entry->ist = 0;
+		entry->flags = PRESENT | RING0 | gate_type;
+		entry->isr_low = isr & 0xffff;
+		entry->isr_mid = (isr >> 16) & 0xffff;
+		entry->isr_high = (isr >> 32) & 0xffffffff;
+		entry->reserved = 0;
+	}
+
+	__asm__ volatile ("lidt %0" : : "m"(idtr));
+}
+
+// Intel manual vol 3 ch 6.3.1
+char *EXCEPTIONS[] = {
+	"Division Error",
+	"Debug",
+	"NMI",
+	"Breakpoint",
+	"Overflow",
+	"BOUND Range Exceeded",
+	"Invalid Opcode",
+	"Device Not Available",
+	"Double Fault",
+	"Coprocessor Segment Overrun",
+	"Invalid TSS",
+	"Segment Not Present",
+	"Stack-Segment Fault",
+	"General Protection Fault",
+	"Page Fault",
+	"Reserved",
+	"x87 Floating-Point Error",
+	"Alignment Check",
+	"Machine Check",
+	"SIMD Floaing-Point Exception",
+	"Virtualization Exception",
+	"Control Protection Exception",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Hypervisor Injection Exception",
+	"VMM Communication Exception",
+	"Security Exception",
+	"Reserved",
+};
+
+void idt_exception_handler(uint64_t exception, uint64_t code, struct isr_regs *state) {
+	switch (exception) {
+	case 0x01: // debug
+		debugger(state, DEBUG_DBG);
+		return;
+	case 0x03: // breakpoint
+		debugger(state, DEBUG_INT3);
+		return;
+	}
+
+	char custom[64];
+	*custom = '\0';
+
+	// page faults store the offending address in cr2
+	if (exception == 0x0E) {
+		strcat(custom, "\nPage fault address: 0x");
+		uint64_t cr2;
+		__asm__ volatile ("mov %%cr2, %0" : "=r"(cr2));
+		ultoa((size_t)cr2, custom + 23, 16);
+	}
+
+	panic_interrupt(
+			(void *)state->rip,
+			(void *)state->rbp,
+			"Exception %s\nError code 0x%lu%s",
+			EXCEPTIONS[exception],
+			code,
+			custom
+	);
+}
+
+void idt_pic_eoi(uint8_t exception) {
+	pic_eoi(exception - PIC_REMAP_OFFSET);
+}
+
+int counter = 0;
+
+void idt_pic_timer(void) {
+	// print a message once we know the timer works
+	// but avoid spamming the logs
+	if (counter == 3) {
+		//kputs("pic timer!\n");
+	}
+	if (counter <= 3) {
+		counter++;
+	}
+}
+
+void idt_pic_keyboard(void) {}
+
+void idt_pic_mouse(void) {}