[MULTITASKING] Preemptive multitasking

kernel/proc/scheduler.c

@@ -2,6 +2,7 @@
 #include <list.h>
 #include <debug.h>
 #include <sse.h>
+#include <apic.h>
 
 LIST(thread_t, ready_queue);
 
@@ -39,6 +40,7 @@ void scheduler()
 {
   while(1)
   {
+    apic_timer_stop();
     thread_t *old = 0, *new = 0;
     if((old = get_last_thread()))
     {
@@ -51,7 +53,8 @@ void scheduler()
       }
     }
 
-    while(!(new = scheduler_next()));
+    while(!(new = scheduler_next()))asm("sti");
+    asm("cli");
 
     if(!process_alive(new->process))
     {
@@ -62,6 +65,7 @@ void scheduler()
     set_last_thread(new);
     switch_process(new->process);
     sse_restore(new->sse_registers);
+    apic_timer(1000000);
     switch_thread(scheduler_th, new);
   }
 }
@@ -71,6 +75,8 @@ void schedule()
   // This function handles swithing to the next thread in the ready queue
 
   thread_t *old = get_current_thread();
+  if(old == scheduler_th)
+    return;
 
   if(old)
   {

kernel/proc/swtch.S

@@ -7,6 +7,7 @@ swtch:
 # Switches stacks preserving callee preserved registers according to System V ABI
   push rbp
   mov rbp, rsp
+  push rdi
   push r15
   push r14
   push r13
@@ -24,5 +25,6 @@ swtch:
   pop r13
   pop r14
   pop r15
+  pop rdi
   leaveq
   ret

kernel/proc/thread.c

@@ -4,6 +4,7 @@
 #include <mem.h>
 #include <list.h>
 #include <debug.h>
+#include <registers.h>
 
 thread_t *current_thread = 0;
 
@@ -16,9 +17,16 @@ thread_t *new_thread(void (*func)(void))
   thread_stack_t *stack = kcalloc(1, sizeof(thread_stack_t));
   thread_t *th = &stack->tcb;
 
-  stack->function_address = (uint64_t)func;
+  stack->thread = (uint64_t)th;
+  stack->function_address = (uint64_t)isr_return;
   stack->RBP = (uint64_t)&stack->zero_frame;
 
+  th->r.rip = (uint64_t)func;
+  th->r.rflags = RFLAGS_IF;
+  th->r.cs = 0x8;
+  th->r.ss = 0x10;
+  th->r.rsp = (uint64_t)&th->stack_pointer;
+
   th->tid = tid++;
   th->state = THREAD_STATE_READY;
   th->stack_pointer = (uint64_t)&stack->RBP;