add interrupts (not yet fully working)

1 files changed, 118 insertions, 0 deletions

diff --git a/src/arch/amd64/idt.c b/src/arch/amd64/idt.c
new file mode 100644
index 0000000..5445560
--- /dev/null
+++ b/src/arch/amd64/idt.c
@@ -0,0 +1,118 @@
+#include <stdint.h>
+#include <stddef.h>
+#include <panic.h>
+#include <lib.h>
+#include <serial.h>
+
+#include "idt.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;
+	void *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 = &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;
+		entry->reserved = 0;
+	}
+
+	__asm__ volatile ("lidt %0" : : "m"(idtr));
+}
+
+
+// Intel manual vol 3 ch 6.3.1
+char *EXCEPTIONS[] = {
+	"Exception 0x00 Divide Error",
+	"Exception 0x01 Debug Exception",
+	"Exception 0x02 NMI Interrupt",
+	"Exception 0x03 Breakpoint",
+	"Exception 0x04 Overflow",
+	"Exception 0x05 BOUND Range Exceeded",
+	"Exception 0x06 Invalid Opcode",
+	"Exception 0x07 Device Not Available",
+	"Exception 0x08 Double Fault",
+	"Exception 0x09 Coprocessor Segment Overrun",
+	"Exception 0x0A Invalid TSS",
+	"Exception 0x0B Segment Not Present",
+	"Exception 0x0C Stack-Segment Fault",
+	"Exception 0x0D General Protection",
+	"Exception 0x0E Page Fault",
+	"Exception 0x0F Reserved",
+	"Exception 0x10 x87 FPU Floating-Point Error",
+	"Exception 0x11 Alignment Check",
+	"Exception 0x12 Machine Check",
+	"Exception 0x13 SIMD Floaing-Point Exception",
+	"Exception 0x14 Virtualization Exception",
+	"Exception 0x15 Control Protection Exception",
+	"Exception 0x16 Reserved",
+	"Exception 0x17 Reserved",
+	"Exception 0x18 Reserved",
+	"Exception 0x19 Reserved",
+	"Exception 0x1A Reserved",
+	"Exception 0x1B Reserved",
+	"Exception 0x1C Reserved",
+	"Exception 0x1D Reserved",
+	"Exception 0x1E Reserved",
+	"Exception 0x1F Reserved",
+};
+
+void idt_exception_handler(uint64_t exception, uint64_t code) {
+	// TODO don't just panic
+	char buf[80];
+	char *end = strcpy(buf, EXCEPTIONS[exception]);
+	end = strcpy(end, "\nError code 0x");
+	ltoa(code, end, 16);
+	panic(buf);
+}
+