1 files changed, 144 insertions, 0 deletions
diff --git a/src/loader/int.c b/src/loader/int.c
new file mode 100644
index 0000000..67b80f0
--- /dev/null
+++ b/src/loader/int.c
@@ -0,0 +1,144 @@
+// MIT License, Copyright (c) 2021 Marvin Borner
+
+#include <int.h>
+#include <log.h>
+#include <pic.h>
+#include <pnc.h>
+
+/**
+ * IDT
+ */
+
+extern u32 int_table[];
+static struct idt_entry idt[256] = { 0 };
+static struct idt_ptr idt_ptr = { 0 };
+
+void idt_install(void)
+{
+	idt_ptr.size = sizeof(idt) - 1;
+	idt_ptr.base = &idt;
+
+	for (u8 i = 0; i < 3; i++)
+		idt[i] = IDT_ENTRY(int_table[i], 0x08, INT_GATE);
+
+	idt[3] = IDT_ENTRY(int_table[3], 0x08, INT_TRAP);
+	idt[4] = IDT_ENTRY(int_table[4], 0x08, INT_TRAP);
+
+	for (u8 i = 5; i < 48; i++)
+		idt[i] = IDT_ENTRY(int_table[i], 0x08, INT_GATE);
+
+	idt[128] = IDT_ENTRY(int_table[48], 0x08, INT_GATE | INT_USER);
+	idt[129] = IDT_ENTRY(int_table[49], 0x08, INT_GATE);
+
+	// Load table
+	__asm__ volatile("lidt %0" : : "m"(idt_ptr));
+
+	// Enable interrupts
+	__asm__ volatile("sti");
+}
+
+/**
+ * Exception (trap) handling
+ */
+
+const char *int_trap_names[32] = {
+	"Division By Zero",
+	"Debug",
+	"Non Maskable Interrupt",
+	"Breakpoint",
+	"Into Detected Overflow",
+	"Out of Bounds",
+	"Invalid Opcode",
+	"No Coprocessor",
+
+	"Double Fault",
+	"Coprocessor Segment Overrun",
+	"Bad TSS",
+	"Segment Not Present",
+	"Stack Fault",
+	"General Protection Fault",
+	"Page Fault",
+	"Unknown Interrupt",
+
+	"Coprocessor Fault",
+	"Alignment Check",
+	"Machine Check",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+	"Reserved",
+};
+
+static void int_trap_handler(struct int_frame *frame)
+{
+	static u8 faulting = 0;
+	faulting++;
+
+	if (faulting == 2) {
+		// Fall back to serial driver
+		serial_print("Double fault, halting immediatly\n");
+		while (1)
+			__asm__ volatile("cli\nhlt");
+	}
+
+	log("%s Exception (code %x) at 0x%x!\n", int_trap_names[frame->int_no], frame->err_code,
+	    frame->eip);
+
+	while (1)
+		__asm__ volatile("cli\nhlt");
+}
+
+/**
+ * Event handling
+ */
+
+static void (*int_event_handlers[16])(void) = { 0 };
+
+void int_event_handler_add(u32 int_no, void (*handler)(void))
+{
+	assert(int_no < COUNT(int_event_handlers));
+	int_event_handlers[int_no] = handler;
+}
+
+static u32 int_event_handler(struct int_frame *frame)
+{
+	u32 int_no = frame->int_no - 32;
+	assert(int_no < COUNT(int_event_handlers));
+	void (*handler)(void) = int_event_handlers[int_no];
+	if (handler)
+		handler();
+
+	return (u32)frame;
+}
+
+/**
+ * Universal handler
+ */
+
+static u8 int_enabled = 1;
+
+u32 int_handler(u32 esp);
+u32 int_handler(u32 esp)
+{
+	struct int_frame *frame = (struct int_frame *)esp;
+	if (frame->int_no < 32) {
+		int_trap_handler(frame);
+	} else if (int_enabled && frame->int_no < 48) {
+		esp = int_event_handler(frame);
+	} else if (frame->int_no >= 48) {
+		panic("Unknown interrupt\n");
+	}
+
+	pic_ack(frame->int_no);
+	return esp;
+}