Add SPT Helper Functions: Insert, Get, Cleanup w/ G

src/userprog/process.c

@@ -24,6 +24,7 @@
 #include "threads/vaddr.h"
 #include "threads/synch.h"
 #include "devices/timer.h"
+#include "vm/page.h"
 #ifdef VM
 #include "vm/frame.h"
 #endif
@@ -364,6 +365,7 @@ process_exit (void)
 
   /* Clean up all open files */
   hash_destroy (&cur->open_files, fd_cleanup);
+  hash_destroy (&cur->pages, page_cleanup);
 
   /* Close the executable file, implicitly allowing it to be written to. */
   if (cur->exec_file != NULL)

src/vm/page.c

@@ -1,4 +1,5 @@
 #include "page.h"
+#include "threads/malloc.h"
 
 /* Hashing function needed for the SPT table. Returns a hash for an entry,
    based on its upage. */
@@ -12,13 +13,60 @@ page_hash (const struct hash_elem *e, UNUSED void *aux)
 /* Comparator function for the SPT table. Compares two entries based on their
    upages. */
 bool
-page_less (const struct hash_elem *a_, const struct hash_elem *b_, UNUSED void *aux)
+page_less (const struct hash_elem *a_, const struct hash_elem *b_,
+           void *aux UNUSED)
 {
   const struct page_entry *a = hash_entry (a_, struct page_entry, elem);
   const struct page_entry *b = hash_entry (b_, struct page_entry, elem);
+
   return a->upage < b->upage;
 }
 
+/* Allocate and insert a new page entry into the thread's page table. */
+struct page_entry *
+page_insert (struct file *file, off_t ofs, void *upage, uint32_t read_bytes,
+             uint32_t zero_bytes, bool writable, enum page_type type)
+{
+  struct page_entry *page = malloc(sizeof (struct page_entry));
+  if (page == NULL)
+    return NULL;
+
+  page->file = file;
+  page->offset = ofs;
+  page->upage = upage;
+  page->read_bytes = read_bytes;
+  page->zero_bytes = zero_bytes;
+  page->writable = writable;
+  page->type = type;
+
+  hash_insert (&thread_current ()->pages, &page->elem);
+  return page;
+}
+
+/* Gets a page_entry from the starting address of the page. Returns NULL if no
+   such page_entry exists in the hash map.*/
+static struct page_entry *
+page_get (void *upage)
+{
+  struct page_entry fake_page_entry;
+  fake_page_entry.upage = upage;
+
+  struct hash_elem *e
+    = hash_find (&thread_current ()->pages, &fake_page_entry.elem);
+
+  if (e == NULL)
+      return NULL;
+
+  return hash_entry (e, struct page_entry, elem);
+}
+
+/* Function to clean up a page_entry. Given the elem of that page_entry, frees
+   the page_entry itself. */
+void
+page_cleanup (struct hash_elem *e, void *aux UNUSED)
+{
+  free (hash_entry (e, struct page_entry, elem));
+}
 
 /* Updates the 'owner' thread's page table entry for virtual address 'upage'
    to have a present bit of 0 and stores the specified swap slot value in the

src/vm/page.h

@@ -24,8 +24,12 @@ struct page_entry {
 };
 
 unsigned page_hash (const struct hash_elem *e, void *aux);
-bool page_less (const struct hash_elem *a_, const struct hash_elem *b_, void *aux);
-
+bool page_less (const struct hash_elem *a_, const struct hash_elem *b_,
+                void *aux);
+struct page_entry *page_insert (struct file *file, off_t ofs, void *upage,
+                                uint32_t read_bytes, uint32_t zero_bytes,
+                                bool writable, enum page_type type);
+void page_cleanup (struct hash_elem *e, void *aux);
 void page_set_swap (struct thread *, void *, size_t);
 size_t page_get_swap (struct thread *, void *);