Merge branch 'vm/memory-mapped-files' into vm/virtual-memory/saleh

src/userprog/exception.c

@@ -259,7 +259,7 @@ try_fetch_page (void *upage, bool write)
   /* Load the page into memory based on the type of data it is expecting. */
   bool success = false;
   switch (page->type) {
-    case PAGE_EXECUTABLE:
+    case PAGE_FILE:
       success = page_load (page, page->writable);
       break;
     default:

src/userprog/process.c

@@ -25,6 +25,7 @@
 #include "threads/synch.h"
 #include "devices/timer.h"
 #include "vm/page.h"
+#include "vm/mmap.h"
 #ifdef VM
 #include "vm/frame.h"
 #endif
@@ -363,6 +364,9 @@ process_exit (void)
   struct thread *cur = thread_current ();
   uint32_t *pd;
 
+  /* Unmap all memory mapped files */
+  mmap_destroy ();
+
   /* Clean up all open files */
   hash_destroy (&cur->open_files, fd_cleanup);
   hash_destroy (&cur->pages, page_cleanup);
@@ -706,7 +710,7 @@ load_segment (struct file *file, off_t ofs, uint8_t *upage,
 
       /* Add the page metadata to the SPT to be lazy loaded later on */
       if (page_insert (file, ofs, upage, page_read_bytes, page_zero_bytes,
-                       writable, PAGE_EXECUTABLE) == NULL)
+                       writable, PAGE_FILE) == NULL)
         return false;
 
       /* Advance. */

src/userprog/syscall.c

@@ -10,12 +10,15 @@
 #include "threads/synch.h"
 #include "userprog/process.h"
 #include "userprog/pagedir.h"
+#include "vm/page.h"
+#include "vm/mmap.h"
 #include <stdio.h>
 #include <stdbool.h>
 #include <syscall-nr.h>
 
 #define MAX_SYSCALL_ARGS 3
 #define EXIT_FAILURE -1
+#define MMAP_FAILURE -1
 
 struct open_file
   {
@@ -45,6 +48,8 @@ static int syscall_write (int fd, const void *buffer, unsigned size);
 static void syscall_seek (int fd, unsigned position);
 static unsigned syscall_tell (int fd);
 static void syscall_close (int fd);
+static mapid_t syscall_mmap (int fd, void *addr);
+static void syscall_munmap (mapid_t mapping);
 
 static struct open_file *fd_get_file (int fd);
 static void validate_user_pointer (const void *ptr, size_t size,
@@ -77,6 +82,8 @@ static const struct syscall_arguments syscall_lookup[] =
   [SYS_SEEK] = {(syscall_function) syscall_seek, 2},
   [SYS_TELL] = {(syscall_function) syscall_tell, 1},
   [SYS_CLOSE] = {(syscall_function) syscall_close, 1},
+  [SYS_MMAP] = {(syscall_function) syscall_mmap, 2},
+  [SYS_MUNMAP] = {(syscall_function) syscall_munmap, 1}
 };
 
 /* The number of syscall functions (i.e, number of elements) within the
@@ -391,6 +398,79 @@ syscall_close (int fd)
     }
 }
 
+/* Handles the syscall for memory mapping a file. */
+static mapid_t
+syscall_mmap (int fd, void *addr)
+{
+  /* Ensure the FD is for a file in the filesystem (not STDIN or STDOUT). */
+  if (fd == STDOUT_FILENO || fd == STDIN_FILENO)
+    return MMAP_FAILURE;
+
+  /* Validate that there is a file associated with the given FD. */
+  struct open_file *file_info = fd_get_file (fd);
+  if (file_info == NULL)
+    return MMAP_FAILURE;
+
+  /* Ensure that the address is page-aligned and it's neither NULL nor zero. */
+  if (addr == 0 || addr == NULL || pg_ofs (addr) != 0)
+    return MMAP_FAILURE;
+
+  /* Reopen the file to obtain a separate and independent reference to the file
+     for the mapping. */
+  struct file *file = file_reopen (file_info->file);
+  if (file == NULL)
+    return MMAP_FAILURE;
+
+  /* Get the size of the file. Mmap fails if the file is empty. */
+  off_t file_size = file_length (file);
+  if (file_size == 0)
+    return MMAP_FAILURE;
+
+  /* Check and ensure that there is enough space in the user virtual memory to
+     hold the entire file. */
+  for (off_t ofs = 0; ofs < file_size; ofs += PGSIZE)
+    {
+      if (page_get (addr + ofs) != NULL)
+        return MMAP_FAILURE;
+    }
+
+  /* Map the file data into the user virtual memory starting from addr. */
+  for (off_t ofs = 0; ofs < file_size; ofs += PGSIZE)
+    {
+      off_t read_bytes = file_size - ofs < PGSIZE ? file_size - ofs : PGSIZE;
+      off_t zero_bytes = PGSIZE - read_bytes;
+
+      if (page_insert (file, ofs, addr + ofs, read_bytes, zero_bytes, true,
+                       PAGE_FILE) == NULL)
+        return MMAP_FAILURE;
+    }
+
+  /* Create a new mapping for the file. */
+  struct mmap_entry *mmap = mmap_insert (file, addr);
+  if (mmap == NULL)
+      return MMAP_FAILURE;
+
+
+  return mmap->mapping;
+}
+
+/* Handles the syscall for unmapping a memory mapped file.
+
+    Pre: mapping is a valid mapping identifier returned by mmap syscall. */
+static void
+syscall_munmap (mapid_t mapping)
+{
+  /* Get the mmap entry from the mapping identifier. */
+  struct mmap_entry *mmap = mmap_get (mapping);
+
+  /* Delete the mmap entry from the hash table. */
+  hash_delete (&thread_current ()->mmap_files, &mmap->elem);
+
+  /* Unmap the mmap entry: free the pages and write back to the file if
+     necessary. NOTE. freeing and cleaning up is also handled by mmap_unmap. */
+  mmap_unmap (mmap);
+}
+
 /* Hashing function needed for the open_file table. Returns a hash for an entry,
    based on its FD. */
 unsigned