From 31403ac7cb825f49fdc04db2a44c9d7f1999b897 Mon Sep 17 00:00:00 2001
From: Themis Demetriades <td1223@ic.ac.uk>
Date: Fri, 6 Dec 2024 00:56:03 +0000
Subject: [PATCH] fix: obtain correct page table entry when performing eviction

---
 src/userprog/exception.c | 2 +-
 src/userprog/syscall.c   | 2 +-
 src/vm/mmap.c            | 3 ++-
 src/vm/page.c            | 6 +++---
 src/vm/page.h            | 2 +-
 5 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/src/userprog/exception.c b/src/userprog/exception.c
index ca2911c..560d7b2 100644
--- a/src/userprog/exception.c
+++ b/src/userprog/exception.c
@@ -252,7 +252,7 @@ fetch_page (void *upage, bool write)
 {
   /* Check if the page is in the supplemental page table. That is, it is a page
      that is expected to be in memory. */
-  struct page_entry *page = page_get (upage);
+  struct page_entry *page = page_get (thread_current (), upage);
   if (page == NULL)
     return false;
 
diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index b1a43dd..8275d51 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -462,7 +462,7 @@ syscall_mmap (int fd, void *addr)
      hold the entire file. */
   for (off_t ofs = 0; ofs < file_size; ofs += PGSIZE)
     {
-      if (page_get (addr + ofs) != NULL)
+      if (page_get (thread_current (), addr + ofs) != NULL)
         return MMAP_FAILURE;
     }
 
diff --git a/src/vm/mmap.c b/src/vm/mmap.c
index b369650..64ad28f 100644
--- a/src/vm/mmap.c
+++ b/src/vm/mmap.c
@@ -1,5 +1,6 @@
 #include "mmap.h"
 #include "page.h"
+#include "threads/thread.h"
 #include "threads/vaddr.h"
 #include "threads/malloc.h"
 #include "userprog/syscall.h"
@@ -70,7 +71,7 @@ mmap_unmap (struct mmap_entry *mmap)
     void *upage = mmap->upage + ofs;
 
     /* Get the SPT page entry for this page. */
-    struct page_entry *page = page_get(upage);
+    struct page_entry *page = page_get(thread_current (), upage);
     if (page == NULL)
       continue;
 
diff --git a/src/vm/page.c b/src/vm/page.c
index 56c6f30..fe71bb5 100644
--- a/src/vm/page.c
+++ b/src/vm/page.c
@@ -47,7 +47,7 @@ struct page_entry *
 page_insert_swapped (void *upage, void *kpage, struct thread *owner)
 {
   /* 1. Initialize swapped page entry. */
-  struct page_entry *page = page_get (upage);
+  struct page_entry *page = page_get (thread_current (), upage);
   if (page == NULL)
     {
       page = malloc (sizeof (struct page_entry));
@@ -103,13 +103,13 @@ page_insert_file (struct file *file, off_t ofs, void *upage,
 /* Gets a page_entry from the starting address of the page. Returns NULL if no
    such page_entry exists in the hash map.*/
 struct page_entry *
-page_get (void *upage)
+page_get (struct thread *thread, 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);
+    = hash_find (&thread->pages, &fake_page_entry.elem);
   if (e == NULL)
       return NULL;
 
diff --git a/src/vm/page.h b/src/vm/page.h
index be7a0aa..2d2f612 100644
--- a/src/vm/page.h
+++ b/src/vm/page.h
@@ -37,7 +37,7 @@ struct page_entry *page_insert_swapped (void *upage, void* kpage,
 struct page_entry *page_insert_file (struct file *file, off_t ofs, void *upage,
                                      uint32_t read_bytes, uint32_t zero_bytes,
                                      bool writable, enum page_type);
-struct page_entry *page_get (void *upage);
+struct page_entry *page_get (struct thread *thread, void *upage);
 bool page_load_file (struct page_entry *page, bool writable);
 void page_cleanup (struct hash_elem *e, void *aux);