feat: add general SPT lock for operations across threads

src/threads/thread.c

@@ -736,6 +736,10 @@ init_thread (struct thread *t, const char *name, int nice, int priority,
   t->recent_cpu = recent_cpu;
   t->priority = t->base_priority;
 
+  #ifdef VM
+  lock_init (&t->spt_lock);
+  #endif
+
   old_level = intr_disable ();
   list_push_back (&all_list, &t->allelem);
   intr_set_level (old_level);

src/threads/thread.h

@@ -149,6 +149,8 @@ struct thread
     struct hash open_files;             /* Hash Table of FD -> Struct File. */
 #endif
 
+    struct lock spt_lock;
+
     void *curr_esp;
 
     /* Owned by thread.c. */

src/vm/page.c

@@ -133,7 +133,8 @@ page_insert_file (struct file *file, off_t ofs, void *upage,
                   enum page_type type)
 {
   /* If page exists, just update it. */
-  struct page_entry *existing = page_get (thread_current (), upage);
+  struct thread *t = thread_current ();
+  struct page_entry *existing = page_get (t, upage);
   if (existing != NULL)
     {
       ASSERT (existing->read_bytes == read_bytes);
@@ -164,11 +165,13 @@ page_insert_file (struct file *file, off_t ofs, void *upage,
 struct page_entry *
 page_get (struct thread *thread, void *upage)
 {
+  lock_acquire (&thread->spt_lock);
   struct page_entry fake_page_entry;
   fake_page_entry.upage = upage;
 
   struct hash_elem *e
     = hash_find (&thread->pages, &fake_page_entry.elem);
+  lock_release (&thread->spt_lock);
   if (e == NULL)
       return NULL;
 
@@ -290,6 +293,7 @@ page_load_file (struct page_entry *page)
 void
 page_cleanup (struct hash_elem *e, void *aux UNUSED)
 {
+  lock_acquire (&thread_current ()->spt_lock);
   struct page_entry *page = hash_entry (e, struct page_entry, elem);
   if (page->type == PAGE_SHARED)
     {
@@ -312,6 +316,7 @@ page_cleanup (struct hash_elem *e, void *aux UNUSED)
       lock_release (&shared_file_pages_lock);
     }
   free (page);
+  lock_release (&thread_current ()->spt_lock);
 }
 
 /* Flags the provided page table entry as representing a swapped out page. */
@@ -343,7 +348,9 @@ page_set_swap (struct thread *owner, uint32_t *pte, size_t swap_slot)
 bool
 page_in_swap (struct thread *owner, void *upage)
 {
+   lock_acquire (&owner->spt_lock);
    uint32_t *pte = lookup_page (owner->pagedir, upage, false);
+   lock_release (&owner->spt_lock);
    return page_in_swap_pte (pte);
 }
 
@@ -360,6 +367,7 @@ page_in_swap_pte (uint32_t *pte)
 size_t
 page_get_swap (struct thread *owner, void *upage)
 {
+   lock_acquire (&owner->spt_lock);  
    uint32_t *pte = lookup_page (owner->pagedir, upage, false);
 
    ASSERT (pte != NULL);
@@ -367,6 +375,7 @@ page_get_swap (struct thread *owner, void *upage)
 
    /* Masks the address bits and returns truncated value. */
    page_flag_swap (pte, false);
+   lock_release (&owner->spt_lock);
    return ((*pte & PTE_ADDR) >> ADDR_START_BIT);
 }