/*! Obtain a frame, either through palloc() or through eviction */
struct frame_table_entry *obtain_frame(enum palloc_flags flag,
struct supp_table *pte) {
void *page;
struct frame_table_entry *newframe;
page = palloc_get_page(flag);
if (!page)
page = frame_evict(flag);
if (!page)
PANIC("run out of frames!\n");
/*! Allocate a frame table entry and initialize it */
newframe = (struct frame_table_entry *)\
malloc(sizeof(struct frame_table_entry));
if (!newframe)
PANIC("malloc failure\n");
newframe->physical_addr = page;
newframe->owner = thread_current();
newframe->spt = pte;
if (f_table.lock.holder != thread_current())
lock_acquire(&f_table.lock);
list_push_back(&f_table.table, &newframe->elem);
lock_release(&f_table.lock);
return newframe;
}
/*
* Searches for a free frame and returns one if available.
* If all frames are full, evict a frame and return pointer to evicted frame.
*/
void*
frame_get_free() {
lock_acquire_re(&vm_lock);
log_debug("+++ frame_get_free (used: %d, own used: %d) +++\n", frametable.used, frametable.own_used);
// TODO
if (frametable.used < frametable.size) {
// some free frames left
while(1) {
if (frametable.frametable[frametable.search_ptr].pte == NULL) {
// FIXME reserve entry by changing pointer
frametable.frametable[frametable.search_ptr].pte = (void*) 0xFFFFFFFF;
frametable.used++;
void* tmp = pagenum_to_page(frametable.search_ptr);
log_debug("### Free page at 0x%08x ###\n", (uint32_t) tmp);
lock_release_re(&vm_lock);
return tmp;
}
// jump to next position
frametable.search_ptr = (frametable.search_ptr + 1) % frametable.size;
}
} else {
// no free frames left
// evict frame
void *tmp = frame_evict();
lock_release_re(&vm_lock);
return tmp;
}
NOT_REACHED();
return NULL;
}
/* Given a virtual address (page) find a frame to put the page in and return
the physical address of the frame */
void*
frame_obtain (enum palloc_flags flags, void* uaddr)
{
struct frame_table_entry* fte;
/* Try and obtain frame in user memory */
void *kaddr = palloc_get_page (flags);
/* Successfully obtained frame */
if (kaddr != NULL)
{
/* Create new frame table entry mapping the given page to the
allocated frame */
fte = (struct frame_table_entry *) malloc
(sizeof (struct frame_table_entry));
fte->owner = thread_current ();
fte->kaddr = kaddr;
fte->uaddr = pg_round_down (uaddr);
lock_acquire (&frame_table_lock);
list_push_front (&frame_table, &fte->elem);
lock_release (&frame_table_lock);
return fte->kaddr;
}
/* Failed to obtain frame */
else
{
/* Perform eviction to release a frame and try allocation again */
if (PAGE_EVICTION)
{
return frame_evict (uaddr);
}
else
{
PANIC ("Failed to allocate frame - eviction disabled.");
}
}
}
void *
frame_alloc (enum palloc_flags flags, struct SP_entry *page_entry)
{
if ((flags & PAL_USER) == 0) {
return NULL;
}
void *frame = palloc_get_page (flags);
if (frame) {
frame_add (frame, page_entry);
} else {
while (!frame) {
frame = frame_evict (flags);
}
if (!frame) {
PANIC ("Frame evict failed. Swap is full!");
}
frame_add (frame, page_entry);
}
return frame;
}