add: idt

headers/gdt.h

@@ -30,3 +30,12 @@ void init_gdt();
 #define GDT_ACCESS_RW_READABLE_FOR_CODE_WRITABLE_FOR_DATA 0b00000010
 #define GDT_ACCESS_A_ACCESSED                             0b00000001
 #define GDT_ACCESS_A_NOT_ACCESSED                         0b00000000
+
+extern uint8_t gdt_entries[GDT_SIZE * 8];
+
+#define GDT_OFFSET_KERNEL_CODE  0x08
+#define GDT_OFFSET_KERNEL_DATA  0x10
+#define GDT_OFFSET_KERNEL_STACK 0x18
+#define GDT_OFFSET_USER_CODE    0x20
+#define GDT_OFFSET_USER_DATA    0x28
+#define GDT_OFFSET_USER_STACK   0x30

headers/idt.h

@@ -6,4 +6,15 @@ struct idt_descriptor {
 	uint32_t offset;
 } __attribute__((packed));
 
+struct idt_entry {
+	uint16_t isr_low;   // The lower 16 bits of the ISR's address
+	uint16_t kernel_cs; // The GDT segment selector that the CPU will load
+	                    // into CS before calling the ISR
+	uint8_t reserved;   // Set to zero
+	uint8_t attributes; // Type and attributes; see the IDT page
+	uint16_t isr_high;  // The higher 16 bits of the ISR's address
+} __attribute__((packed));
+
 #define IDT_SIZE 256
+
+void init_idt(void);

src/gdt/gdt.c

@@ -42,7 +42,7 @@ void init_gdt(void)
 	set_gdt_entry_value(gdt_entries + 0x00, 0, 0, 0, 0); // Null segment
 
 	set_gdt_entry_value(
-	    gdt_entries + 0x08, 0, 0xFFFFF,
+	    gdt_entries + GDT_OFFSET_KERNEL_CODE, 0, 0xFFFFF,
 	    GDT_ACCESS_P_VALID | GDT_ACCESS_DPL_KERNEL_MODE |
 		GDT_ACCESS_S_CODE_OR_DATA | GDT_ACCESS_E_EXECUTABLE |
 		GDT_ACCESS_DC_NOT_CONFORM |
@@ -50,7 +50,7 @@ void init_gdt(void)
 		GDT_ACCESS_A_ACCESSED,
 	    GDT_FLAG_32BIT_MODE | GDT_FLAG_PAGE_MODE); // Kernel code
 	set_gdt_entry_value(
-	    gdt_entries + 0x10, 0, 0xFFFFF,
+	    gdt_entries + GDT_OFFSET_KERNEL_DATA, 0, 0xFFFFF,
 	    GDT_ACCESS_P_VALID | GDT_ACCESS_DPL_KERNEL_MODE |
 		GDT_ACCESS_S_CODE_OR_DATA | GDT_ACCESS_E_NOT_EXECUTABLE |
 		GDT_ACCESS_DC_NOT_CONFORM |
@@ -58,7 +58,7 @@ void init_gdt(void)
 		GDT_ACCESS_A_ACCESSED,
 	    GDT_FLAG_32BIT_MODE | GDT_FLAG_PAGE_MODE); // Kernel data
 	set_gdt_entry_value(
-	    gdt_entries + 0x18, 0, 0xFFFFF,
+	    gdt_entries + GDT_OFFSET_KERNEL_STACK, 0, 0xFFFFF,
 	    GDT_ACCESS_P_VALID | GDT_ACCESS_DPL_KERNEL_MODE |
 		GDT_ACCESS_S_CODE_OR_DATA | GDT_ACCESS_E_NOT_EXECUTABLE |
 		GDT_ACCESS_DC_CONFORM |
@@ -67,7 +67,7 @@ void init_gdt(void)
 	    GDT_FLAG_32BIT_MODE | GDT_FLAG_PAGE_MODE); // Kernel stack
 
 	set_gdt_entry_value(
-	    gdt_entries + 0x20, 0, 0xFFFFF,
+	    gdt_entries + GDT_OFFSET_USER_CODE, 0, 0xFFFFF,
 	    GDT_ACCESS_P_VALID | GDT_ACCESS_DPL_USER_MODE |
 		GDT_ACCESS_S_CODE_OR_DATA | GDT_ACCESS_E_EXECUTABLE |
 		GDT_ACCESS_DC_CONFORM |
@@ -75,7 +75,7 @@ void init_gdt(void)
 		GDT_ACCESS_A_ACCESSED,
 	    GDT_FLAG_32BIT_MODE | GDT_FLAG_PAGE_MODE); // User code
 	set_gdt_entry_value(
-	    gdt_entries + 0x28, 0, 0xFFFFF,
+	    gdt_entries + GDT_OFFSET_USER_DATA, 0, 0xFFFFF,
 	    GDT_ACCESS_P_VALID | GDT_ACCESS_DPL_USER_MODE |
 		GDT_ACCESS_S_CODE_OR_DATA | GDT_ACCESS_E_NOT_EXECUTABLE |
 		GDT_ACCESS_DC_NOT_CONFORM |
@@ -83,7 +83,7 @@ void init_gdt(void)
 		GDT_ACCESS_A_ACCESSED,
 	    GDT_FLAG_32BIT_MODE | GDT_FLAG_PAGE_MODE); // User data
 	set_gdt_entry_value(
-	    gdt_entries + 0x30, 0, 0xFFFFF,
+	    gdt_entries + GDT_OFFSET_USER_STACK, 0, 0xFFFFF,
 	    GDT_ACCESS_P_VALID | GDT_ACCESS_DPL_USER_MODE |
 		GDT_ACCESS_S_CODE_OR_DATA | GDT_ACCESS_E_NOT_EXECUTABLE |
 		GDT_ACCESS_DC_CONFORM |

src/interrupt/handler.c

@@ -3,6 +3,8 @@
 
 #include <stdint.h>
 
+__attribute__((noreturn)) void exception_handler(void);
+
 void exception_handler(void)
 {
 	int8_t index = -1;

src/interrupt/idt.c

@@ -1,36 +1,59 @@
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "gdt.h"
 #include "idt.h"
 
-uint16_t idt_entries[IDT_SIZE * 4];
+extern void *isr_stub_table[];
-struct idt_descriptor idtr;
 
+__attribute__((aligned(0x10))) static struct idt_entry idt_entries[IDT_SIZE];
+static struct idt_descriptor idtr;
+/*
 static void set_idt_entry_value(uint16_t *target, uint32_t offset,
                                 uint16_t selector, uint8_t dpl,
                                 uint8_t gate_type)
 {
         // Encode the offset
-	target[0] = offset & 0xFFFF;
+        target[0] = offset & 0xFFFF;         // Low 16 bits
-	target[3] = (offset >> 16) & 0xFFFF;
+        target[3] = (offset >> 16) & 0xFFFF; // High 16 bits
 
-	// Encode the presence
+        // Encode the presence (bit 15)
         target[1] |= 1 << 15;
 
-	// Encode the CPU Privilege Levels
+        // Encode the CPU Privilege Levels (DPL)
-	target[1] = (0b11 << 13) & dpl;
+        target[1] &= ~(0b11 << 13);      // Clear previous DPL
+        target[1] |= (dpl & 0b11) << 13; // Set new DPL
 
+        // Clear bit 12 (always 0 for interrupts)
         target[1] &= ~(1 << 12);
 
         // Encode Gate Type
-	target[1] |= gate_type & 0x0F00;
+        target[1] &= ~0x0F00;                 // Clear previous gate type
+        target[1] |= (gate_type & 0x0F) << 8; // Set new gate type
 
         // Encode selector
         target[2] = selector;
+}*/
+
+void idt_set_descriptor(uint8_t index, void *isr, uint8_t flags)
+{
+	struct idt_entry *descriptor = &idt_entries[index];
+
+	descriptor->isr_low = (uint32_t)isr & 0xFFFF;
+	descriptor->kernel_cs = GDT_OFFSET_KERNEL_CODE;
+	descriptor->attributes = flags;
+	descriptor->isr_high = (uint32_t)isr >> 16;
+	descriptor->reserved = 0;
 }
 
 void init_idt(void)
 {
-	idtr.size = 8 * IDT_SIZE - 1;
+	idtr.offset = (uintptr_t)&idt_entries[0];
-	idtr.offset = (uint32_t)&idt_entries;
+	idtr.size = (uint16_t)sizeof(struct idt_entry) * IDT_SIZE - 1;
+
+	for (uint8_t i = 0; i < 32; i++)
+		idt_set_descriptor(i, isr_stub_table[i], 0x8E);
+
+	__asm__ volatile("lidt %0" : : "m"(idtr));
+	__asm__ volatile("sti");
 }

src/interrupt/isr.s

@@ -3,12 +3,14 @@
 
 .macro isr_err_stub nb
 isr_stub_\nb:
+	movb bl, \nb
     call exception_handler
     iret 
 .endm
 
 .macro isr_no_err_stub nb
 isr_stub_\nb:
+	movb bl, \nb
     call exception_handler
     iret
 .endm

src/kernel.c

@@ -1,5 +1,6 @@
 #include "alloc.h"
 #include "gdt.h"
+#include "idt.h"
 #include "kpanic.h"
 #include "kprintf.h"
 #include "memory.h"
@@ -27,13 +28,6 @@ void kernel_main(void)
 	terminal_initialize();
 	init_gdt();
 	init_memory();
-	kprintf(KERN_CRIT "KERN_CRIT\n");
+	init_idt();
-	kprintf(KERN_ALERT "KERN_ALERT\n");
-	kprintf(KERN_WARNING "KERN_WARNING\n");
-	kprintf(KERN_NOTICE "KERN_NOTICE\n");
-	kprintf(KERN_INFO "KERN_INFO\n");
-	kprintf(KERN_DEBUG "KERN_DEBUG\n");
-	void *ptr = vmalloc(100);
-	kprintf("%d\n", ksize(ptr));
 	shell_init();
 }