147 lines
2.9 KiB
C
147 lines
2.9 KiB
C
#include "isr.h"
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#include "../drivers/port.h"
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#include "../console.h"
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enum {
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IDT_HANDLERS = 256,
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};
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typedef struct {
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uint16_t low_offset;
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uint16_t selector;
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uint8_t always0;
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uint8_t flags;
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uint16_t high_offset;
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} __attribute__((packed)) idt_gate_t;
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idt_gate_t idt[IDT_HANDLERS];
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#define low_16(address) (uint16_t)((address) & 0xFFFF)
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#define high_16(address) (uint16_t)(((address) >> 16) & 0xFFFF)
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void set_idt_gate(int n, uint32_t handler) {
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idt[n].low_offset = low_16(handler);
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idt[n].selector = 0x08; // see GDT
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idt[n].always0 = 0;
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// 0x8E = 1 00 0 1 110
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// P DPL 0 D Type
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idt[n].flags = 0x8E;
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idt[n].high_offset = high_16(handler);
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}
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// defined in vectors.S
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extern uint32_t default_handlers[];
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void init_idt() {
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if (default_handlers[0] == 0) {
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panic("handler table empty\n");
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}
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for (int i = 0; i < IDT_HANDLERS; i++) {
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set_idt_gate(i, default_handlers[i]);
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}
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}
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const char *exception_messages[] = {
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"Division By Zero",
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"Debug",
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"Non Maskable Interrupt",
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"Breakpoint",
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"Into Detected Overflow",
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"Out of Bounds",
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"Invalid Opcode",
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"No Coprocessor",
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"Double Fault",
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"Coprocessor Segment Overrun",
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"Bad TSS",
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"Segment Not Present",
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"Stack Fault",
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"General Protection Fault",
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"Page Fault",
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"Unknown Interrupt",
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"Coprocessor Fault",
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"Alignment Check",
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"Machine Check",
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};
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#define ARRLEN(a) (sizeof(a) / sizeof(a[0]))
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static isr_t interrupt_handlers[IDT_HANDLERS];
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void register_interrupt_handler(uint8_t i, isr_t handler) {
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interrupt_handlers[i] = handler;
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}
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void trap(registers_t *r) {
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if (r->int_no < 32) {
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const char* msg = "Reserved";
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if (r->int_no < ARRLEN(exception_messages)) {
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msg = exception_messages[r->int_no];
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}
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printk(msg);
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printk("\n");
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}
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/* Handle the interrupt in a more modular way */
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if (interrupt_handlers[r->int_no] != 0) {
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isr_t handler = interrupt_handlers[r->int_no];
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handler(r);
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}
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// EOI
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if (r->int_no >= 40) {
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port_byte_out(0xA0, 0x20); /* follower */
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}
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if (r->int_no >= 32) {
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port_byte_out(0x20, 0x20); /* leader */
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}
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}
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static void init_pic() {
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// ICW1
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port_byte_out(0x20, 0x11);
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port_byte_out(0xA0, 0x11);
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// ICW2
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port_byte_out(0x21, 0x20);
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port_byte_out(0xA1, 0x28);
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// ICW3
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port_byte_out(0x21, 0x04);
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port_byte_out(0xA1, 0x02);
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// ICW4
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port_byte_out(0x21, 0x01);
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port_byte_out(0xA1, 0x01);
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// OCW1
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port_byte_out(0x21, 0x0);
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port_byte_out(0xA1, 0x0);
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}
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typedef struct {
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uint16_t limit;
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void* base;
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} __attribute__((packed)) idt_register_t;
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static idt_register_t idt_reg;
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void load_idt() {
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init_idt();
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idt_reg.base = &idt;
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idt_reg.limit = sizeof(idt) - 1;
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asm("lidt (%0)" : : "r"(&idt_reg));
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init_pic();
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}
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void cli() {
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asm("cli");
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}
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void sti() {
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asm("sti");
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}
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