started on isr/idt stuff

kernel/idt.c

@@ -0,0 +1,58 @@
+#include <stdint.h>
+#include <idt.h>
+
+#define IDT_MAX_DESCRIPTORS 256
+
+#define ATTR_KERN_32 0x8E // active(1), ring 0 (00), interrupt gate(0), 32 bit (1110)
+
+#define SEGMENT_KERN 0x08
+
+extern void load_idt(void);
+extern void enable_int(void);
+
+extern void isr0();
+extern void isr1();
+extern void isr8();
+extern void isr13();
+extern void isr14();
+extern void isr32();
+extern void isr33();
+
+void* isr_stub_table[256] = {
+    [0] = isr0,
+    [1] = isr1,
+    [8] = isr8,
+    [13] = isr13,
+    [14] = isr14,
+    [32] = isr32,
+    [33] = isr33,
+};
+
+idt_entry idt[IDT_MAX_DESCRIPTORS];
+idt_ptr idtr;
+
+void set_idtr(uint8_t vector, void* isr, uint8_t attributes) {
+    idt_entry* desc = &idt[vector];
+
+    desc->isr_low    = (uint32_t)isr & 0xFFFF;
+    desc->kernel_cs  = SEGMENT_KERN;
+    desc->reserved   = 0;
+    desc->attributes = attributes;
+    desc->isr_high   = ((uint32_t)isr >> 16) & 0xFFFF;
+}
+
+void init_idt() {
+    idtr.limit = (sizeof(idt_entry) * IDT_MAX_DESCRIPTORS) - 1;
+    idtr.base  = (uint32_t)&idt;
+
+    for (int i = 0; i < IDT_MAX_DESCRIPTORS; i++) {
+        if (isr_stub_table[i] != 0) {
+            set_idtr(i, isr_stub_table[i], ATTR_KERN_32);
+        } else {
+            set_idtr(i, 0, 0);
+        }
+    }
+
+    load_idt();
+    enable_int();
+}

kernel/idt.h

@@ -0,0 +1,19 @@
+#ifndef KIDT_H
+#define KIDT_H
+
+#include <stdint.h>
+
+typedef struct {
+    uint16_t isr_low;   // The lower 16 bits of the ISR's address
+    uint16_t kernel_cs; // The GDT segment selector the CPU will load into CS
+    uint8_t  reserved;  // Set to 0
+    uint8_t  attributes;// Type and attributes flags
+    uint16_t isr_high;  // The higher 16 bits of the ISR's address
+} idt_entry __attribute__((packed));
+
+typedef struct  {
+    uint16_t limit;
+    uint32_t base;
+} idt_ptr __attribute__((packed));
+
+#endif

kernel/idt_stubs.s

@@ -0,0 +1,54 @@
+.code32 
+
+.macro ISR_NOERRCODE num
+.global isr\num
+isr\num:
+    pushl $0           
+    pushl $\num        
+    jmp isr_common_stub
+.endm
+
+.macro ISR_ERRCODE num
+.global isr\num
+isr\num:
+    pushl $\num       
+    jmp isr_common_stub
+.endm
+
+.extern common_interrupt_handler
+isr_common_stub:
+    pushal             
+
+    pushl %esp         
+    call common_interrupt_handler
+    addl $4, %esp      
+
+    popal              
+    addl $8, %esp      
+    iret            
+
+.global master_eoi
+master_eoi:
+    movb $0x20, %al
+    outb %al, $0x20
+    ret
+
+.extern idtr
+.global load_idt
+load_idt:
+    lidt idtr 
+    ret
+
+.global enable_int
+enable_int:
+    sti
+    ret
+
+ISR_NOERRCODE 0    # Divide by Zero
+ISR_NOERRCODE 1    # Debug
+ISR_ERRCODE   8    # Double Fault (Has Error Code!)
+ISR_ERRCODE   13   # General Protection Fault (Has Error Code!)
+ISR_ERRCODE   14   # Page Fault (Has Error Code!)
+
+ISR_NOERRCODE 32   # IRQ0 - Timer
+ISR_NOERRCODE 33   # IRQ1 - Keyboard

kernel/interrupts.c

@@ -0,0 +1,46 @@
+#include "lib/print.h"
+#include <stdint.h>
+
+extern void master_eoi(void);
+
+struct registers {
+    uint32_t edi, esi, ebp, esp_dummy, ebx, edx, ecx, eax;
+    
+    uint32_t int_no;    
+    uint32_t error_code;
+    
+    uint32_t eip, cs, eflags, useresp, ss;
+};
+
+const char* err_messages[32] = {
+    [0] = "Divide by 0",
+    [1] = "",
+    [8] = "",
+    [13] = "General Protection Fault",
+    [14] = "Page Fault",
+};
+
+void common_interrupt_handler(struct registers *regs) {
+    switch (regs->int_no) {
+        case 0:
+        case 1:
+        case 8:
+        case 13:
+        case 14:
+            kprint("CPU Error: ");
+            kprint(err_messages[regs->int_no]);
+            kprint("\n");
+            break;
+        case 32:
+            // wake the PIC timer driver
+            master_eoi();
+            break;
+        case 33:    
+            // wake the keyboard driver
+            master_eoi();
+            break;
+        default:
+            kprint("Received unhandled interrupt\n");
+            return;
+    }
+}

kernel/kmain.c

@@ -1,6 +1,13 @@
 #include <lib/print.h>
 #include <lib/stream.h>
 
+#include <idt.h>
+
+#include <stdint.h>
+
+extern void init_idt();
+extern idt_entry create_idt_entry(uint32_t addr, uint16_t segment, uint8_t attributes);
+
 void kernel_main(void) 
 {
   extern print_stream_t vga_print_stream;
@@ -9,4 +16,6 @@ void kernel_main(void)
   kout->trunc();
 
   kprint("RockOS booting...");
+
+  init_idt();
 }