arch: i386: cleanup everything and reorganize

Clean up everything in the i386 arch directory. This code has been in
dire need of refactoring for a long while. All the inline assembly
functions and the data structures related to the architecture should be
placed into their own header file. Now the scheduler can access
registers and ISRs without having to deal with arch-specific code.

Signed-off-by: Danny Holman <dholman@gymli.org>

8 files changed, 414 insertions, 81 deletions

diff --git a/arch/i386/kernel/gdt.c b/arch/i386/kernel/gdt.c
new file mode 100644
index 0000000..c0cf127
--- /dev/null
+++ b/arch/i386/kernel/gdt.c
@@ -0,0 +1,58 @@
+#include <kernel/gdt.h>
+#include <kernel/asm.h>
+#include <kernel/string.h>
+
+struct gdt_entry desc[6];
+struct gdt_ptr gp;
+struct tss_entry tss_entry;
+
+void gdt_set_gate(int num, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran) {
+        desc[num].base_low = (base & 0xFFFF);
+        desc[num].base_middle = (base >> 16) & 0xFF;
+        desc[num].base_high = (base >> 24) & 0xFF;
+
+        desc[num].limit_low = (limit & 0xFFFF);
+        desc[num].gran = (limit >> 16) & 0x0F;
+        desc[num].gran |= (gran & 0xF0);
+        desc[num].access = access;
+}
+
+void write_tss(int num, uint32_t ss0, uint32_t esp0) {
+        uint32_t base = (uint32_t)&tss_entry;
+        uint32_t limit = base + sizeof(struct tss_entry);
+
+        gdt_set_gate(num, base, limit, 0x89, 0x00);
+        memset(&tss_entry, 0x0, sizeof(tss_entry));
+        
+        tss_entry.ss0 = ss0;
+        tss_entry.esp0 = esp0;
+        tss_entry.cs = 0x0B;
+        tss_entry.ss = 0x13;
+        tss_entry.ds = 0x13;
+        tss_entry.es = 0x13;
+        tss_entry.fs = 0x13;
+        tss_entry.gs = 0x13;
+        tss_entry.iomap_base = sizeof(tss_entry);
+}
+
+void set_kernel_esp(uint32_t esp) {
+        tss_entry.esp0 = esp;
+}
+
+void gdt_install(void) {
+        gp.limit = (sizeof(struct gdt_entry) * 6) - 1;
+        gp.base = (uint32_t)&desc;
+
+        gdt_set_gate(0, 0, 0, 0, 0);
+        gdt_set_gate(1, 0, 0xFFFFF, 0x9A, 0xCF);
+        gdt_set_gate(2, 0, 0xFFFFF, 0x92, 0xCF);
+        gdt_set_gate(3, 0, 0xFFFFF, 0xFA, 0xCF);
+        gdt_set_gate(4, 0, 0xFFFFF, 0xF2, 0xCF);
+        
+        uint32_t esp;
+        __asm__ volatile("movl %%esp, %0" : "=r"(esp));
+        write_tss(5, 0x10, esp);
+
+        flush_gdt();
+        flush_tss();
+}
diff --git a/arch/i386/kernel/idt.c b/arch/i386/kernel/idt.c
new file mode 100644
index 0000000..5c0766c
--- /dev/null
+++ b/arch/i386/kernel/idt.c
@@ -0,0 +1,152 @@
+#include <kernel/idt.h>
+#include <kernel/syscall.h>
+#include <kernel/panic.h>
+#include <kernel/gdt.h>
+#include <kernel/asm.h>
+#include <kernel/io.h>
+#include <kernel/pic.h>
+#include <kernel/string.h>
+#include <kernel/paging.h>
+#include <stdint.h>
+
+__attribute__((aligned(0x10)))
+struct idt_entry idt[256];
+struct idt_ptr idtr;
+
+const char* exceptions[] = {
+        "Division by zero",
+        "Debug",
+        "Non-maskable interrupt",
+        "Breakpoint",
+        "Overflow",
+        "Out-of-bounds",
+        "Invalid opcode",
+        "FPU not available",
+        "Double fault",
+        "RESERVED",
+        "Invalid TSS",
+        "Segment not present",
+        "Stack fault",
+        "General protection fault",
+        "Page fault",
+        "RESERVED",
+        "FPU exception",
+        "Alignment check",
+        "Machine check",
+        "FPU-SIMD exception",
+        "Virtualization exception",
+        "Control protection"
+        "RESERVED",
+        "Hypervisor injection",
+        "VMM exception",
+        "Security exception",
+        "RESERVED",
+        "Triple fault",
+        "RESERVED"
+};
+
+void exception_handler(struct regs *regs) {
+        switch (regs->isr_vector) {
+                case 0x00:
+                        panic("Division by zero in kernel address space");
+                        break;
+                case 0x06:
+                        panic("Invalid opcode in kernel address space");
+                        break;
+                case 0x08:
+                        panic("Double fault in interrupt handler");
+                        break;
+                case 0x0D:
+                        panic("Protection fault in kernel address space");
+                        break;
+                case 0x0E:
+                        page_fault_handler(regs);
+                        break;
+                default:
+                        panic("Unhandled exception");
+        }
+}
+
+void interrupt_handler(struct regs regs) {
+        if (regs.isr_vector < 32) {
+                exception_handler(&regs);
+        } else if (regs.isr_vector < 48) {
+                irq_dispatch(&regs);
+        } else {
+                switch (regs.isr_vector) {
+                        case 0x80:
+                                handle_syscall(&regs);
+                                break;
+                        default:
+                                panic("Unmapped interrupt");
+                }
+        }
+}
+
+void idt_set_gate(uint8_t num, void (*handler)(void), uint16_t cs, uint8_t flags) {
+        struct idt_entry *desc = &idt[num];
+        desc->isr_low = (uint16_t)(((uint32_t)handler >> 0) & 0xFFFF);
+        desc->isr_high = (uint16_t)(((uint32_t)handler >> 16) & 0xFFFF);
+        desc->reserved = 0;
+        desc->kernel_cs = cs;
+        desc->flags = flags;
+}
+
+void idt_install(void) {
+        idtr.limit = (uint16_t)sizeof(struct idt_entry) * 256 - 1;
+        idtr.base = (uint32_t)idt;
+
+        idt_set_gate(0x0, isr_stub_0, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x1, isr_stub_1, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x2, isr_stub_2, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x3, isr_stub_3, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x4, isr_stub_4, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x5, isr_stub_5, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x6, isr_stub_6, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x7, isr_stub_7, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x8, isr_stub_8, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x9, isr_stub_9, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0xA, isr_stub_10, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0xB, isr_stub_11, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0xC, isr_stub_12, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0xD, isr_stub_13, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0xE, isr_stub_14, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0xF, isr_stub_15, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x10, isr_stub_16, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x11, isr_stub_17, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x12, isr_stub_18, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x13, isr_stub_19, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x14, isr_stub_20, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x15, isr_stub_21, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x16, isr_stub_22, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x17, isr_stub_23, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x18, isr_stub_24, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x19, isr_stub_25, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x1A, isr_stub_26, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x1B, isr_stub_27, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x1C, isr_stub_28, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x1D, isr_stub_29, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x1E, isr_stub_30, 0x08, IDT_EXCEPTION);
+        idt_set_gate(0x1F, isr_stub_31, 0x08, IDT_EXCEPTION);
+
+        idt_set_gate(0x20, irq_stub_0, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x21, irq_stub_1, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x22, irq_stub_2, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x23, irq_stub_3, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x24, irq_stub_4, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x25, irq_stub_5, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x26, irq_stub_6, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x27, irq_stub_7, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x28, irq_stub_8, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x29, irq_stub_9, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x2A, irq_stub_10, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x2B, irq_stub_11, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x2C, irq_stub_12, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x2D, irq_stub_13, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x2E, irq_stub_14, 0x08, IDT_INTERRUPT);
+        idt_set_gate(0x2F, irq_stub_15, 0x08, IDT_INTERRUPT);
+
+        idt_set_gate(0x80, syscall_stub, 0x08, IDT_INTERRUPT);
+
+        __asm__ volatile("lidt %0" : : "memory"(idtr));
+}
diff --git a/arch/i386/kernel/isr.s b/arch/i386/kernel/isr.s
new file mode 100644
index 0000000..55db35e
--- /dev/null
+++ b/arch/i386/kernel/isr.s
@@ -0,0 +1,129 @@
+.section .text
+
+.macro isr_err_stub num
+.global isr_stub_\num
+.type isr_stub_\num, @function
+isr_stub_\num:
+        cli
+        pushl $\num
+        jmp isr_frame_asm
+.endm
+.macro isr_no_err_stub num
+.global isr_stub_\num
+.type isr_stub_\num, @function
+isr_stub_\num:
+        cli
+        pushl $0
+        pushl $\num
+        jmp isr_frame_asm
+.endm
+
+.macro irq_stub num
+.global irq_stub_\num
+.type irq_stub_\num, @function
+irq_stub_\num:
+        cli
+        pushl $0
+        pushl $\num+32
+        jmp isr_frame_asm
+.endm
+
+.global syscall_stub
+syscall_stub:
+        cli
+        pushl $0
+        pushl $0x80
+        jmp isr_frame_asm
+
+isr_frame_asm:
+        pushl %eax
+        pushl %ebx
+        pushl %ecx
+        pushl %edx
+        pushl %esi
+        pushl %edi
+
+        movl %cr0, %eax
+        pushl %eax
+        movl %cr2, %eax
+        pushl %eax
+        movl %cr3, %eax
+        pushl %eax
+        movl %cr4, %eax
+        pushl %eax
+
+        pushl %esp
+        call set_kernel_esp
+        addl $4, %esp
+
+        cld
+        call interrupt_handler
+
+        popl %eax
+        movl %eax, %cr4
+        popl %eax
+        movl %eax, %cr3
+        popl %eax
+        movl %eax, %cr2
+        popl %eax
+        movl %eax, %cr0
+
+        popl %edi
+        popl %esi
+        popl %edx
+        popl %ecx
+        popl %ebx
+        popl %eax
+        addl $8, %esp
+
+        iret
+
+isr_no_err_stub 0
+isr_no_err_stub 1
+isr_no_err_stub 2
+isr_no_err_stub 3
+isr_no_err_stub 4
+isr_no_err_stub 5
+isr_no_err_stub 6
+isr_no_err_stub 7
+isr_err_stub    8
+isr_no_err_stub 9
+isr_err_stub    10
+isr_err_stub    11
+isr_err_stub    12
+isr_err_stub    13
+isr_err_stub    14
+isr_no_err_stub 15
+isr_no_err_stub 16
+isr_err_stub    17
+isr_no_err_stub 18
+isr_no_err_stub 19
+isr_no_err_stub 20
+isr_err_stub    21
+isr_no_err_stub 22
+isr_no_err_stub 23
+isr_no_err_stub 24
+isr_no_err_stub 25
+isr_no_err_stub 26
+isr_no_err_stub 27
+isr_no_err_stub 28
+isr_err_stub    29
+isr_err_stub    30
+isr_no_err_stub 31
+
+irq_stub 0
+irq_stub 1
+irq_stub 2
+irq_stub 3
+irq_stub 4
+irq_stub 5
+irq_stub 6
+irq_stub 7
+irq_stub 8
+irq_stub 9
+irq_stub 10
+irq_stub 11
+irq_stub 12
+irq_stub 13
+irq_stub 14
+irq_stub 15
diff --git a/arch/i386/kernel/keyboard.c b/arch/i386/kernel/keyboard.c
index 4e4bc9b..96aea3a 100644
--- a/arch/i386/kernel/keyboard.c
+++ b/arch/i386/kernel/keyboard.c
@@ -100,6 +100,9 @@ static uint8_t* keymaps[4] = {
         keymap_control,
 };
 
+char keyboard_buffer[4096];
+int kbuf_pos = 0;
+
 char keyboard_getchar(void) {
         static int shift = 0;
         uint8_t st = inb(KB_STAT);
@@ -133,10 +136,9 @@ char keyboard_getchar(void) {
         return c;
 }
 
-void keyboard_handler(struct isr_frame *frame) {
+void keyboard_handler(void) {
         char c = keyboard_getchar();
-        // TODO: actually put this in a buffer
         if (c != -1)
-                fb_putchar(c);
+                keyboard_buffer[kbuf_pos++];
         return;
 }
diff --git a/arch/i386/kernel/paging.c b/arch/i386/kernel/paging.c
index 54539ac..b2a1392 100644
--- a/arch/i386/kernel/paging.c
+++ b/arch/i386/kernel/paging.c
@@ -10,63 +10,42 @@ static uintptr_t kend = (uintptr_t)&_kernel_end - 0xC0000000;
 
 static uintptr_t page_directory[1024] __attribute__((aligned(PAGE_SIZE)));
 static uintptr_t first_page_table[1024] __attribute__((aligned(PAGE_SIZE)));
+static uintptr_t second_page_table[1024] __attribute__((aligned(PAGE_SIZE)));
 
 static int paging_enabled = 0;
 
-static uint32_t dma_zone_bitmap[DMA_BITMAP_SZ];
-static uint32_t buddy_bitmap[BDY_BITMAP_SZ];
-static struct pfa_buddy first_buddy;
-
-static void _pfa_init(void) {
-        first_buddy.start = 0x01000000;
-        first_buddy.bitmap = buddy_bitmap;
+uint32_t* init_page_table(uint32_t flags) {
+        uint32_t *ret = kmalloc(sizeof(uint32_t)*1024);
+        for (int i = 0; i < 1024; i++)
+                ret[i] = flags;
 }
 
-static void _pfa_alloc(uintptr_t paddr) {
-        uintptr_t index = (paddr & 0xFFFFF000) / 4096 / 32;
-        uintptr_t bit = (paddr & 0xFFFFF000) / 4096 % 32;
-        uint32_t *bitmap;
-        if (paddr < 0x01000000)
-                bitmap = dma_zone_bitmap;
-        else
-                bitmap = first_buddy.bitmap;
-
-        bitmap[index] |= (1 << bit);
-}
-
-static void _pfa_free(uintptr_t paddr) {
-        uintptr_t index = (paddr & 0xFFFFF000) / 4096 / 32;
-        uintptr_t bit = (paddr & 0xFFFFF000) / 4096 % 32;
-        uint32_t *bitmap;
-        if (paddr < 0x01000000)
-                bitmap = dma_zone_bitmap;
-        else
-                bitmap = first_buddy.bitmap;
-
-        bitmap[index] &= ~(1 << bit);
+uint32_t* init_page_dir(uint32_t flags) {
+        uint32_t *ret = init_page_table(flags);
+        ret[0] = ((uintptr_t)&first_page_table - 0xC0000000) | 3;
+        ret[768] = ((uintptr_t)&second_page_table - 0xC0000000) | 3;
 }
 
 void paging_init(void) {
-        _pfa_init();
-        for (int i = 0; i < 1024; i++)
-                page_directory[i] = 0x00000002;
+        for (int i = 0; i < 1024; i++) {
+                page_directory[i] = PD_RW;
+                first_page_table[i] = PD_RW;
+                second_page_table[i] = PD_RW;
+        }
 
         page_directory[1023] = ((uintptr_t)&page_directory - 0xC0000000) | 3;
         page_directory[0] = ((uintptr_t)&first_page_table - 0xC0000000) | 3;
-        page_directory[768] = ((uintptr_t)&first_page_table - 0xC0000000) | 3;
-        for (uintptr_t i = kstart; i < kend; i += 4096) {
-                _pfa_alloc(get_vaddr(i));
-                map_page(page_directory, i, get_vaddr(i), 0x003);
-        }
+        page_directory[768] = ((uintptr_t)&second_page_table - 0xC0000000) | 3;
+        for (uintptr_t i = kstart; i < kend; i += PAGE_SIZE)
+                map_page(page_directory, i, i + 0xC0000000, 0x003);
 
-        load_page_dir(((uintptr_t)&page_directory) - 0xC0000000);
-        enable_paging();
+        enable_paging(((uintptr_t)&page_directory) - 0xC0000000);
         paging_enabled = 1;
         return;
 }
 
-void page_fault_handler(struct isr_frame *frame) {
-        uintptr_t errno = frame->errno;
+void page_fault_handler(struct regs *regs) {
+        uintptr_t errno = regs->isr_err;
 
         uintptr_t fault_addr;
         __asm__ volatile("movl %%cr2, %0" : "=r"(fault_addr));
@@ -76,9 +55,9 @@ void page_fault_handler(struct isr_frame *frame) {
         int reserved = errno & ERR_RESERVED;
         int ifetch = errno & ERR_INST;
 
+        uintptr_t first_free;
         if (!present)
-                _pfa_alloc(fault_addr);
-                map_page(NULL, fault_addr, fault_addr, 0x003);
+                map_page(regs->cr3, fault_addr, fault_addr, PD_PRES | PD_RW | PD_USR);
         if (user)
                 panic("Usermode attempted to read supervisor page");
         if (rw)
@@ -89,8 +68,17 @@ void page_fault_handler(struct isr_frame *frame) {
                 panic("Task paging instruction fetch failure");
 }
 
-uintptr_t get_vaddr(uintptr_t paddr) {
-        return paddr + 0xC0000000;
+uintptr_t get_paddr(uintptr_t vaddr) {
+        uint32_t pdindex = (uint32_t)vaddr >> 22;
+        uint32_t ptindex = (uint32_t)vaddr >> 12 & 0x03FF;
+
+        uint32_t *pd = (uint32_t*)0xFFFFF000;
+        if (*pd & PD_PRES != 1)
+                return NULL;
+        uint32_t *pt = ((uint32_t*)0xFFC00000) + (0x400 * pdindex);
+        if (*pt & PD_PRES != 1)
+                return NULL;
+        return (uintptr_t)((pt[ptindex] & ~0xFFF) + ((uint32_t)vaddr & 0xFFF));
 }
 
 void map_page(uint32_t *pd, uintptr_t paddr, uintptr_t vaddr, uint32_t flags) {
diff --git a/arch/i386/kernel/pic.c b/arch/i386/kernel/pic.c
index 7a51763..3cf1d94 100644
--- a/arch/i386/kernel/pic.c
+++ b/arch/i386/kernel/pic.c
@@ -1,6 +1,6 @@
 #include <kernel/pic.h>
 
-static void (*irq_handlers[16])(struct isr_frame *frame);
+static void (*irq_handlers[16])(struct regs *regs);
 
 void pic_eoi(uint8_t irq) {
         if (irq >= 8)
@@ -24,27 +24,27 @@ void pic_remap(void) {
         outb(PIC2_DATA, a2);
 }
 
-static uint16_t __pic_get_irq_reg(int ocw3) {
+static uint16_t _pic_get_irq_reg(int ocw3) {
         outb(PIC1_COMMAND, ocw3);
         outb(PIC2_COMMAND, ocw3);
         return (inb(PIC2_COMMAND) << 8) | inb(PIC1_COMMAND);
 }
 
 uint16_t pic_get_irr(void) {
-        return __pic_get_irq_reg(PIC_READ_IRR);
+        return _pic_get_irq_reg(PIC_READ_IRR);
 }
 
 uint16_t pic_get_isr(void) {
-        return __pic_get_irq_reg(PIC_READ_ISR);
+        return _pic_get_irq_reg(PIC_READ_ISR);
 }
 
-void register_irq_handler(uint8_t irq, void (*handler)(struct isr_frame *frame)) {
+void register_irq_handler(uint8_t irq, void (*handler)(struct regs *regs)) {
         irq_handlers[irq] = handler;
 }
 
-void irq_dispatch(struct isr_frame *frame) {
-        (*irq_handlers[frame->vector-32])(frame);
-        pic_eoi(frame->vector-32);
+void irq_dispatch(struct regs *regs) {
+        (*irq_handlers[regs->isr_vector-32])(regs);
+        pic_eoi(regs->isr_vector-32);
         return;
 }
 
diff --git a/arch/i386/kernel/syscall.c b/arch/i386/kernel/syscall.c
index 7bdb24b..27e1c60 100644
--- a/arch/i386/kernel/syscall.c
+++ b/arch/i386/kernel/syscall.c
@@ -1,32 +1,36 @@
 #include <kernel/syscall.h>
+#include <kernel/panic.h>
+#include <kernel/framebuffer.h>
+#include <kernel/keyboard.h>
+#include <kernel/string.h>
 #include <kernel/io.h>
 #include <stddef.h>
 
-int handle_syscall(struct isr_frame *frame) {
-        switch (frame->eax) {
-                case SYS_REBOOT:
-                        kprintf("REBOOT NOT SUPPORTED\n");
-                        break;
-                default:
-                        kprintf("Error: Invalid system call number: %d\n", frame->eax);
-                        halt_catch_fire(frame);
+extern char *keyboard_buffer;
+extern uint32_t kbuf_pos;
+
+void sys_read(struct regs *regs) {
+        if (regs->ebx == 1) {
+                while (kbuf_pos > regs->edx);
+                memcpy((char*)regs->ecx, keyboard_buffer, regs->edx);
         }
-        return 0;
 }
 
-void dump_reg(struct isr_frame *frame) {
-        kprintf("Registers at interrupt:\n");
-        kprintf("\tEAX = %x\n", frame->eax);
-        kprintf("\tEBX = %x\n", frame->ebx);
-        kprintf("\tECX = %x\n", frame->ecx);
-        kprintf("\tEDX = %x\n", frame->edx);
-        kprintf("\tESI = %x\n", frame->esi);
-        kprintf("\tEDI = %x\n", frame->edi);
-        kprintf("\tEIP = %x\n", frame->eip);
-        kprintf("Current code selector: %x\n", frame->cs);
+void sys_write(struct regs *regs) {
+        if (regs->ebx == 0)
+                fb_write((char*)regs->ecx, regs->edx);
 }
 
-void dump_stack(uint32_t esp, size_t len) {
-        for (uint32_t i = 0; i < len; i++)
-                kprintf("%x:\t%x\n", esp+i, *(uint32_t*)(esp+i));
+int handle_syscall(struct regs *regs) {
+        switch (regs->eax) {
+                case SYS_READ:
+                        sys_read(regs);
+                        break;
+                case SYS_WRITE:
+                        sys_write(regs);
+                        break;
+                default:
+                        panic("Invalid system call number");
+        }
+        return 0;
 }
diff --git a/arch/i386/kernel/timer.c b/arch/i386/kernel/timer.c
index 9e53fbd..4aafed1 100644
--- a/arch/i386/kernel/timer.c
+++ b/arch/i386/kernel/timer.c
@@ -5,7 +5,7 @@
 
 static uint32_t num_ticks = 0;
 
-void timer_handler(struct isr_frame *frame) {
+void timer_handler(struct regs *regs) {
         num_ticks++;
         if (num_ticks == 3) {
                 num_ticks = 0;
@@ -14,12 +14,12 @@ void timer_handler(struct isr_frame *frame) {
 }
 
 void timer_init(void) {
-        asm __volatile__("cli");
+        disable_ints();
         int divisor = 1193182 / 100;
         outb(0x43, 0x34);
         outb(0x40, divisor && 0xFF);
         outb(0x40, divisor && 0xFF00 >> 8);
-        asm __volatile__("sti");
+        enable_ints();
 
         //uint8_t read = 0;
         //outb(0x43, 0xE2);