Quick and dirty IDT setup

src/kernel/Makefile

@@ -2,8 +2,8 @@ ifeq ($(MITTOS64),)
 $(error Unsupported environment! See README)
 endif
 
-SRC := $(wildcard **/*.[cS])
+SRC := $(wildcard **/*.[cS]*)
-OBJ := $(patsubst %, %.o, $(basename $(SRC)))
+OBJ := $(patsubst %, %.o, $(basename $(basename $(SRC))))
 
 CFLAGS ?= -Wall -Wextra -pedantic
 CFLAGS += -ffreestanding -mcmodel=large
@@ -20,6 +20,9 @@ LDFLAGS := -n -nostdlib -lgcc -T Link.ld
 kernel: $(OBJ)
 	$(LINK.c) $^ -o $@
 
+%.S: %.S.py
+	python $^ > $@
+
 # Automatically generate dependency files
 # Those keep track of which header files are used by which source files
 DEP := $(OBJ:.o=.d)
@@ -39,6 +42,7 @@ clean:
 	rm -rf $(OBJ) $(DEP) kernel
 
 .PHONY: install clean
+.INTERMEDIATE: $(basename $(filter %.py, $(SRC)))
 
 # Include generated dependency files
 include $(DEP)

src/kernel/boot/kmain.c

@@ -4,6 +4,8 @@
 #include <debug.h>
 #include <multiboot.h>
 
+void interrupt_init();
+
 void kmain(uint64_t multiboot_magic, void *multiboot_data)
 {
   serial_init(PORT_COM1);
@@ -14,6 +16,15 @@ void kmain(uint64_t multiboot_magic, void *multiboot_data)
 
   debug_info("Kernel was loaded with command line \"%s\", by <%s>\n", kernel_boot_data.commandline, kernel_boot_data.bootloader);
 
+  interrupt_init();
+
+  // Force a divide by zero exception
+  // ISR 0
+  int a = 5, b = 0;
+  int c = a/b;
+
+  debug("a: %d b:%d c:%d\n", a,b,c);
+
   debug_ok("Boot \"Complete\"\n");
 
   PANIC("Reached end of kernel main function\n");

src/kernel/interrupts/idt.c

@@ -0,0 +1,89 @@
+#include <stdint.h>
+#include <memory.h>
+#include <debug.h>
+
+struct int_gate_descriptor
+{
+  uint16_t base_l;
+  uint16_t cs;
+  uint8_t ist;
+  uint8_t flags;
+  uint16_t base_m;
+  uint32_t base_h;
+  uint32_t ignored;
+} __attribute__((packed));
+
+struct idtr
+{
+  uint16_t len;
+  struct int_gate_descriptor *addr;
+} __attribute__((packed));
+
+typedef struct
+{
+  uint64_t rax;
+  uint64_t rbx;
+  uint64_t rcx;
+  uint64_t rdx;
+  uint64_t rsi;
+  uint64_t rdi;
+  uint64_t rbp;
+  uint64_t r8;
+  uint64_t r9;
+  uint64_t r10;
+  uint64_t r11;
+  uint64_t r12;
+  uint64_t r13;
+  uint64_t r14;
+  uint64_t r15;
+
+  uint64_t int_no;
+  uint64_t err_code;
+
+  uint64_t rip;
+  uint64_t cs;
+  uint64_t rflags;
+  uint64_t rsp;
+  uint64_t ss;
+} registers;
+
+void load_idt(struct idtr *);
+
+#define NUM_INTERRUPTS 256
+
+struct int_gate_descriptor idt[NUM_INTERRUPTS];
+struct idtr idtr;
+
+
+extern uintptr_t isr_table[];
+
+void idt_set_gate(uint32_t num, uintptr_t vector, uint16_t cs, uint8_t ist, uint8_t flags)
+{
+  idt[num].base_l = vector & 0xFFFF;
+  idt[num].base_m = (vector >> 16) & 0xFFFF;
+  idt[num].base_h = (vector >> 32) & 0xFFFFFFFF;
+  idt[num].cs = cs;
+  idt[num].ist = ist;
+  idt[num].flags = flags;
+}
+
+void interrupt_init()
+{
+  memset(idt, 0, sizeof(idt));
+
+  for(int i=0; i < NUM_INTERRUPTS; i++)
+  {
+    idt_set_gate(i, isr_table[i], 0x8, 0, 0x8E);
+  }
+
+  idtr.addr = idt;
+  idtr.len = sizeof(idt)-1;
+  load_idt(&idtr);
+}
+
+registers *int_handler(registers *r)
+{
+  (void)r;
+  debug("Interrupt %d\n", r->int_no);
+  for(;;);
+}

src/kernel/interrupts/idt.tt

@@ -0,0 +1,31 @@
+// vim: ft=c
+#include <ttest.h>
+#include <debug.h>
+#undef debug
+#define debug(...)
+#include "idt.c"
+
+uintptr_t isr_table[] ={};
+void load_idt(struct idtr *_)
+{
+  (void)_;
+}
+
+TEST(idt_set_gate_correctly_sets_address_L)
+{
+  idt_set_gate(1, 0x1234567890ABCDEF, 0, 0, 0);
+
+  ASSERT_EQ_INT(idt[1].base_l, 0xCDEF);
+}
+TEST(idt_set_gate_correctly_sets_address_M)
+{
+  idt_set_gate(1, 0x1234567890ABCDEF, 0, 0, 0);
+
+  ASSERT_EQ_INT(idt[1].base_m, 0x90AB);
+}
+TEST(idt_set_gate_correctly_sets_address_H)
+{
+  idt_set_gate(1, 0x1234567890ABCDEF, 0, 0, 0);
+
+  ASSERT_EQ_INT(idt[1].base_h, 0x12345678);
+}

src/kernel/interrupts/isr.S.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+num_isr = 256
+pushes_error = [8, 10, 11, 12, 13, 14, 17]
+
+print '''
+.intel_syntax noprefix
+.extern isr_common
+'''
+
+
+print '// Interrupt Service Routines'
+for i in range(num_isr):
+    print '''isr{0}:
+    cli
+    {1}
+    push {0}
+    jmp isr_common
+    '''.format(i,
+        'push 0' if i not in pushes_error else 'nop')
+
+print ''
+print '''
+// Vector table
+
+.section .data
+.global isr_table
+isr_table:'''
+
+for i in range(num_isr):
+    print '  .quad isr{}'.format(i)

src/kernel/interrupts/isr_common.S

@@ -0,0 +1,50 @@
+.intel_syntax noprefix
+
+.global load_idt
+load_idt:
+  lidt [rdi]
+  ret
+
+.extern int_handler
+.global isr_common
+.global isr_return
+
+isr_common:
+  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:
+  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
+  add rsp, 0x10
+  iretq