[INTERRUPTS] Exception handling

kernel/interrupts/interrupts.c

@@ -0,0 +1,67 @@
+#include <int.h>
+#include <debug.h>
+#include <registers.h>
+#include <string.h>
+#include <stdint.h>
+
+struct int_gate_descriptor idt[NUM_INTERRUPTS];
+struct idtr idtr;
+int_handler_t int_handlers[NUM_INTERRUPTS];
+
+void idt_set(uint32_t num, void *vector, uint16_t cs, uint8_t ist, uint8_t flags)
+{
+  uintptr_t v = (uintptr_t)vector;
+  idt[num].base_l = v & 0xFFFF;
+  idt[num].base_m = (v >> 16) & 0xFFFF;
+  idt[num].base_h = (v >> 32) & 0xFFFFFFFF;
+  idt[num].cs = cs;
+  idt[num].ist = ist;
+  idt[num].flags = flags;
+}
+
+void interrupt_init()
+{
+  // Clear IDT and interrupt handler list
+  memset(idt, 0, sizeof(idt));
+  memset(int_handlers, 0, sizeof(int_handlers));
+
+  // Register all vectors in the IDT
+  extern void *isr_table[];
+  for(int i=0; i < NUM_INTERRUPTS; i++)
+  {
+    idt_set(i, isr_table[i], 0x8, 0,
+        (IDT_PRESENT | IDT_DPL0 | IDT_INTERRUPT));
+  }
+
+  // Setup pointer and load IDT
+  idtr.addr = (uint64_t)idt;
+  idtr.len = sizeof(idt)-1;
+  load_idt(&idtr);
+}
+
+int_handler_t register_int_handler(uint32_t num, int_handler_t h)
+{
+  // Replace the handler for an interrupt
+  // Return the old handler
+  int_handler_t old = int_handlers[num];
+  int_handlers[num] = h;
+  return old;
+}
+
+
+registers_t *int_handler(registers_t *r)
+{
+  // If a handler is registered, pass everything onto it
+  if(int_handlers[r->int_no])
+    return int_handlers[r->int_no](r);
+
+  debug("\n===============================================================================\n");
+  debug_error("Unhandled interrupt!\n");
+  print_registers(r);
+
+#ifndef NDEBUG
+  asm("int_handler_breakpoint:");
+#endif
+
+  for(;;);
+}

kernel/interrupts/isr.S.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+print('''
+.intel_syntax noprefix
+.extern isr_common
+''')
+
+print('// Interrupt Service Routines')
+for i in range(255):
+    print('''isr{0}:
+    cli
+    {1}
+    push {0}
+    jmp isr_common
+    '''.format(i, 
+        'push 0' if i not in [8, 10, 11, 12, 13, 14, 17] else 'nop'))
+
+print('''
+
+// Vector table
+
+.section .data
+.global isr_table
+isr_table:
+''')
+for i in range(255):
+    print('    .quad isr{}'.format(i))

kernel/interrupts/isr_common.S

@@ -0,0 +1,49 @@
+.intel_syntax noprefix
+
+.extern int_handler
+.global isr_common
+.global isr_return
+
+isr_common:
+  // Push all registers
+  push r15
+  push r14
+  push r13
+  push r12
+  push r11
+  push r10
+  push r9
+  push r8
+  push rbp
+  push rdi
+  push rsi
+  push rdx
+  push rcx
+  push rbx
+  push rax
+  mov rdi, rsp
+  call int_handler
+  mov rdi, rax
+
+isr_return:
+  // Return and restore stack
+  mov rsp, rdi
+  pop rax
+  pop rbx
+  pop rcx
+  pop rdx
+  pop rsi
+  pop rdi
+  pop rbp
+  pop r8
+  pop r9
+  pop r10
+  pop r11
+  pop r12
+  pop r13
+  pop r14
+  pop r15
+  // Pop error code and fault number
+  add rsp, 16
+  iretq
+