/**
* Allocate a new frame,
* and return the address of the associated page.
*/
void*
vm_frame_allocate (enum palloc_flags flags, void *upage)
{
lock_acquire (&frame_lock);
void *frame_page = palloc_get_page (PAL_USER | flags);
if (frame_page == NULL) {
// page allocation failed.
/* first, swap out the page */
struct frame_table_entry *f_evicted = pick_frame_to_evict( thread_current()->pagedir );
#if DEBUG
printf("f_evicted: %x th=%x, pagedir = %x, up = %x, kp = %x, hash_size=%d\n", f_evicted, f_evicted->t,
f_evicted->t->pagedir, f_evicted->upage, f_evicted->kpage, hash_size(&frame_map));
#endif
ASSERT (f_evicted != NULL && f_evicted->t != NULL);
// clear the page mapping, and replace it with swap
ASSERT (f_evicted->t->pagedir != (void*)0xcccccccc);
pagedir_clear_page(f_evicted->t->pagedir, f_evicted->upage);
bool is_dirty = false;
is_dirty = is_dirty || pagedir_is_dirty(f_evicted->t->pagedir, f_evicted->upage);
is_dirty = is_dirty || pagedir_is_dirty(f_evicted->t->pagedir, f_evicted->kpage);
swap_index_t swap_idx = vm_swap_out( f_evicted->kpage );
vm_supt_set_swap(f_evicted->t->supt, f_evicted->upage, swap_idx);
vm_supt_set_dirty(f_evicted->t->supt, f_evicted->upage, is_dirty);
vm_frame_do_free(f_evicted->kpage, true); // f_evicted is also invalidated
frame_page = palloc_get_page (PAL_USER | flags);
ASSERT (frame_page != NULL); // should success in this chance
}
struct frame_table_entry *frame = malloc(sizeof(struct frame_table_entry));
if(frame == NULL) {
// frame allocation failed. a critical state or panic?
lock_release (&frame_lock);
return NULL;
}
frame->t = thread_current ();
frame->upage = upage;
frame->kpage = frame_page;
frame->pinned = true; // can't be evicted yet
// insert into hash table
hash_insert (&frame_map, &frame->helem);
list_push_back (&frame_list, &frame->lelem);
lock_release (&frame_lock);
return frame_page;
}
/* Evicte random frame */
struct vm_frame *vm_evict_frame(struct supp_page_entry *s){
ASSERT(!list_empty(&vm_frames_list));
/* Choose frame - FIFO */
lock_acquire(&vm_lock);
struct list_elem *e = list_front(&vm_frames_list);
struct vm_frame *victim = list_entry(e, struct vm_frame, elem);
lock_release(&vm_lock);
/* Settings */
pagedir_clear_page(victim->thread->pagedir, victim->spte->upage);
victim->spte->type = S;
victim->spte->swap_idx = vm_swap_out(victim->page);
victim->thread = thread_current();
victim->spte = s;
palloc_free_page(victim->page);
return victim;
}
