feat: incorporate lazy-loading data & helpers into supplemental page table

src/userprog/process.c

@@ -118,7 +118,6 @@ process_execute (const char *cmd)
 
 static void *get_usr_kpage (enum palloc_flags flags, void *upage);
 static void free_usr_kpage (void *kpage);
-static bool install_page (void *upage, void *kpage, bool writable);
 
 static bool process_init_stack (char *cmd_saveptr, void **esp, char *file_name);
 static void *push_to_stack (void **esp, void *data, size_t data_size);
@@ -809,7 +808,7 @@ free_usr_kpage (void *kpage)
    with palloc_get_page().
    Returns true on success, false if UPAGE is already mapped or
    if memory allocation fails. */
-static bool
+bool
 install_page (void *upage, void *kpage, bool writable)
 {
   struct thread *t = thread_current ();

src/userprog/process.h

@@ -8,4 +8,6 @@ int process_wait (tid_t);
 void process_exit (void);
 void process_activate (void);
 
+bool install_page (void *upage, void *kpage, bool writable);
+
 #endif /* userprog/process.h */