interrupts!!!! :D

kernel/Makefile

@@ -26,6 +26,11 @@ DIRS = $(wildcard $(SRCDIR)/*)
 
 kernel: $(OBJS) link
 
+$(OBJDIR)/interrupts/interrupts.o: $(SRCDIR)/interrupts/interrupts.cpp
+	@ echo !==== COMPILING $^
+	@ mkdir -p $(@D)
+	$(CC) -mno-red-zone -mgeneral-regs-only -ffreestanding -c $^ -o $@
+
 $(OBJDIR)/%.o: $(SRCDIR)/%.cpp
 	@ echo !==== COMPILING $^
 	@ mkdir -p $(@D)

kernel/src/BasicRenderer.cpp

@@ -1,5 +1,7 @@
 #include "BasicRenderer.h"
 
+BasicRenderer* GlobalRenderer;
+
 BasicRenderer::BasicRenderer(Framebuffer* framebuffer, PSF1_FONT* psf1_Font) {
 	targetFramebuffer = framebuffer;
 	PSF1_Font = psf1_Font;

kernel/src/BasicRenderer.h

@@ -12,4 +12,6 @@ class BasicRenderer {
 		unsigned int Colour;
 		void Print(const char* str);
 		void PutChar(char chr, unsigned int xOff, unsigned int yOff);
-};
+};
+
+extern BasicRenderer* GlobalRenderer;

kernel/src/interrupts/IDT.cpp

@@ -0,0 +1,15 @@
+#include "IDT.h"
+
+void IDTDescEntry::SetOffset(uint64_t offset) {
+	offset0 = (uint16_t)(offset & 0x000000000000ffff);         // lower 16 bits -> offset0
+	offset1 = (uint16_t)((offset & 0x00000000ffff0000) >> 16); // upper 16 bits -> offset1
+	offset2 = (uint32_t)((offset & 0xffffffff00000000) >> 32); // upper 32 bits -> offset2
+}
+
+uint64_t IDTDescEntry::GetOffset() {
+	uint64_t offset = 0;
+	offset |= (uint64_t)offset0;
+	offset |= (uint64_t)offset1 << 16;
+	offset |= (uint64_t)offset2 << 32;
+	return offset;
+}

kernel/src/interrupts/IDT.h

@@ -0,0 +1,24 @@
+#pragma once
+#include <stdint.h>
+
+#define IDT_TA_InterruptGate 0b10001110
+#define IDT_TA_CallGate      0b10001100
+#define IDT_TA_TrapGate      0b10001111
+
+struct IDTDescEntry {
+	uint16_t offset0; // lower 16 bits of offset
+	uint16_t selector; // segment selector
+	uint8_t ist; // interrupt stack table offset
+	uint8_t type_attr; // interrupt gate, trap gate, etc...
+	uint16_t offset1; // upper 16 bits of offset
+	uint32_t offset2; // upper 32 bits of offset
+	uint32_t ignore; // unused
+
+	void SetOffset(uint64_t offset);
+	uint64_t GetOffset();
+};
+
+struct IDTR {
+	uint16_t Limit;
+	uint64_t Offset;
+}__attribute__((packed));

kernel/src/interrupts/interrupts.cpp

@@ -0,0 +1,6 @@
+#include "interrupts.h"
+
+__attribute__((interrupt)) void PageFault_Handler(struct interrupt_frame* frame) {
+	GlobalRenderer->Print("Page fault caught!");
+	while (true);
+}

kernel/src/interrupts/interrupts.h

@@ -0,0 +1,6 @@
+#pragma once
+#include "../BasicRenderer.h"
+
+struct interrupt_frame;
+
+__attribute__((interrupt)) void PageFault_Handler(struct interrupt_frame* frame);

kernel/src/kernel.cpp

@@ -2,12 +2,11 @@
 
 extern "C" void _start(BootInfo* bootInfo) {
 	KernelInfo kernelInfo = InitializeKernel(bootInfo);
-	BasicRenderer newRenderer = BasicRenderer(bootInfo->framebuffer, bootInfo->psf1_Font);
 	PageTableManager* pageTableManager = kernelInfo.pageTableManager;
 
-	newRenderer.Print("Kernel initialized successfully! (we didn't crash lol)");
-	newRenderer.cursorPosition = {0, newRenderer.cursorPosition.y + 18};
-
+	GlobalRenderer->Print("Kernel initialized successfully!");
+	GlobalRenderer->cursorPosition = {0, GlobalRenderer->cursorPosition.y + 18};
+	
 	// make sure we never return from our OS
 	while (true);
 }

kernel/src/kernelUtil.cpp

@@ -6,6 +6,8 @@ extern "C" void __stack_chk_fail(void) {
 
 #include "kernelUtil.h"
 #include "gdt/gdt.h"
+#include "interrupts/IDT.h"
+#include "interrupts/interrupts.h"
 
 KernelInfo kernelInfo;
 PageTableManager pageTableManager = NULL;
@@ -41,8 +43,25 @@ void PrepareMemory(BootInfo* bootInfo){
     kernelInfo.pageTableManager = &pageTableManager;
 }
 
+IDTR idtr;
+void PrepareInterrupts() {
+	idtr.Limit = 0x0FFF;
+	idtr.Offset = (uint64_t)GlobalAllocator.RequestPage();
+	memset((void*)idtr.Offset, 0, 0x1000);
 
+	IDTDescEntry* int_PageFault = (IDTDescEntry*)(idtr.Offset + 0xE * sizeof(IDTDescEntry));
+	int_PageFault->SetOffset((uint64_t)PageFault_Handler);
+	int_PageFault->type_attr = IDT_TA_InterruptGate;
+	int_PageFault->selector = 0x08; // kernel code segment
+
+	// load idt
+	asm("lidt %0" : : "m" (idtr));
+}
+
+BasicRenderer r = BasicRenderer(NULL, NULL);
 KernelInfo InitializeKernel(BootInfo* bootInfo){
+	r = BasicRenderer(bootInfo->framebuffer, bootInfo->psf1_Font);
+	GlobalRenderer = &r;
 
 	GDTDescriptor gdtDescriptor;
 	gdtDescriptor.Size = sizeof(GDT) - 1;
@@ -53,5 +72,7 @@ KernelInfo InitializeKernel(BootInfo* bootInfo){
 
     memset(bootInfo->framebuffer->BaseAddress, 0, bootInfo->framebuffer->BufferSize);
 
+	PrepareInterrupts();
+
     return kernelInfo;
 }