From 28cd9deb9b1b94213d2925b97c4bb593393b68dd Mon Sep 17 00:00:00 2001
From: rami <rami.kaldany@pm.me>
Date: Wed, 3 Jul 2024 11:23:21 -0400
Subject: [PATCH] switch to ring3

---
 Makefile        |  1 +
 kernel/init.asm | 32 ++++++++++++++++++++++++++++++++
 kernel/kernel.c | 14 +++++++++++---
 3 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/Makefile b/Makefile
index f562848..0629f87 100644
--- a/Makefile
+++ b/Makefile
@@ -20,6 +20,7 @@ ISO := Hazel.iso
 CFLAGS    := -ffreestanding -Wall -Wextra -Werror -I $(INCLUDEDIR) -I lib
 LDFLAGS   := -ffreestanding -nostdlib -lgcc -T kernel/kernel.ld
 QEMUFLAGS := -cdrom $(BUILDDIR)/$(ISO) \
+			 -d int
 	     -m 512M \
 	     -serial stdio
 
diff --git a/kernel/init.asm b/kernel/init.asm
index 6abe6a5..47f47f1 100644
--- a/kernel/init.asm
+++ b/kernel/init.asm
@@ -57,6 +57,24 @@ pit_isr:
     call pit_handler
     iret
 
+global jmp_user_mode
+jmp_user_mode:
+    mov ax, (4*8) | 3
+    mov ds, ax
+    mov es, ax 
+    mov fs, ax 
+    mov gs, ax ; SS is handled by iret
+
+    mov eax, esp
+    push (4*8) | 3
+    push eax
+    pushf
+    push (3*8) | 3
+    extern test_entry
+    push test_entry
+
+    iret
+
 extern exception_handler
 %macro isr_err_stub 1
 isr_stub_%+%1:
@@ -142,6 +160,20 @@ gdt_kern_data:
     db 0b10010010
     db 0b11001111
     db 0x00
+gdt_user_code:
+    dw 0xffff
+    dw 0x0000
+    db 0x00
+    db 0b11111010
+    db 0b11001111
+    db 0x00
+gdt_user_data:
+    dw 0xffff
+    dw 0x0000
+    db 0x00
+    db 0b11110010
+    db 0b11001111
+    db 0x00
 gdt_end:
 
 gdtp:
diff --git a/kernel/kernel.c b/kernel/kernel.c
index 1d85259..b3bf1b5 100644
--- a/kernel/kernel.c
+++ b/kernel/kernel.c
@@ -12,6 +12,12 @@ struct idtr idtr = {0};
 
 extern uint32_t isr_stub_table[32];
 extern void pit_isr(void);
+extern void jmp_user_mode(void);
+
+void test_entry(void) {
+    asm volatile ("cli" ::);
+    for (;;) {}
+}
 
 void exception_handler(int_stack_frame_t r) {
     LOG("Exception 0x%X (0x%X) has occurred\nEAX: 0x%08X\nECX: 0x%08X\nEDX: 0x%08X\nEBX: 0x%08X\nESI: 0x%08X\nEDI: 0x%08X\nEBP: 0x%08X\nESP: 0x%08X\n",
@@ -36,7 +42,7 @@ void kernel(multiboot_info_t *info) {
     LOG("Kernel log being sent to COM1\n");
 
     if (!mmap_init()) goto halt;
-    LOG("%d bytes of RAM detected\nCreated a %d byte large physical memory map at 0x%08X\n", ctx.mmap_size*BLOCK_SIZE*8, ctx.mmap_size, ctx.mmap);
+    LOG("%d bytes of RAM detected\nCreated a %d byte large physical memory map at 0x%08X\n", ctx.mmap_size*BLOCK_SIZE*8, ctx.mmap_size, (uint32_t)ctx.mmap);
 
     for (int i = 0; i < 32; i++) {
         idt_encode_entry(idt, i, isr_stub_table[i], GDT_SEGMENT_SELECTOR(1, 0), TRAP_GATE_32 | INT_RING0 | INT_PRESENT);
@@ -48,10 +54,12 @@ void kernel(multiboot_info_t *info) {
 
     asm volatile ("lidt %0" :: "m"(idtr));
     pic_remap(PIC_1_START, PIC_2_START);
-    asm volatile ("sti" ::);
+    //asm volatile ("sti" ::);
 
     ctx.ticks = 0;
-    pit_init();
+    //pit_init();
+
+    jmp_user_mode(); 
 
 halt:
     for (;;) {}