add dynamic stack growing

1 files changed, 36 insertions, 18 deletions

diff --git a/userprog/process.c b/userprog/process.c
index 15883d9..2771e76 100644
--- a/userprog/process.c
+++ b/userprog/process.c
@@ -552,24 +552,24 @@ load_segment (struct file *file, off_t ofs, uint8_t *upage,
 
   file_seek (file, ofs);
   while (read_bytes > 0 || zero_bytes > 0)
-  {
-    /* Calculate how to fill this page.
-         We will read PAGE_READ_BYTES bytes from FILE
-         and zero the final PAGE_ZERO_BYTES bytes. */
-    size_t page_read_bytes = read_bytes < PGSIZE ? read_bytes : PGSIZE;
-    size_t page_zero_bytes = PGSIZE - page_read_bytes;
-
-    /* add segment to page table for on demand loading */
-    if (!page_table_insert_segment (file, ofs, upage, page_read_bytes,
-          page_zero_bytes, writable))
-      return false;
-
-    /* Advance. */
-    read_bytes -= page_read_bytes;
-    zero_bytes -= page_zero_bytes;
-    ofs += page_read_bytes;
-    upage += PGSIZE;
-  }
+    {
+      /* Calculate how to fill this page.
+           We will read PAGE_READ_BYTES bytes from FILE
+           and zero the final PAGE_ZERO_BYTES bytes. */
+      size_t page_read_bytes = read_bytes < PGSIZE ? read_bytes : PGSIZE;
+      size_t page_zero_bytes = PGSIZE - page_read_bytes;
+
+      /* add segment to page table for on demand loading */
+      if (!page_table_insert_segment (file, ofs, upage, page_read_bytes,
+            page_zero_bytes, writable))
+        return false;
+
+      /* Advance. */
+      read_bytes -= page_read_bytes;
+      zero_bytes -= page_zero_bytes;
+      ofs += page_read_bytes;
+      upage += PGSIZE;
+    }
   return true;
 }
 
@@ -686,6 +686,24 @@ setup_stack (uint32_t **esp, const char *args)
   return true;
 }
 
+/* expand the stack of the process by one new page
+   which will be installed at the address of UPAGE */
+bool
+process_grow_stack (void *upage)
+{
+  uint8_t *kpage = palloc_get_page (PAL_USER | PAL_ZERO);
+  if (kpage == NULL)
+      return false;
+
+  if (!process_install_page (upage, kpage, true))
+    {
+      palloc_free_page (kpage);
+      return false;
+    }
+
+  return true;
+}
+
 /* Adds a mapping from user virtual address UPAGE to kernel
    virtual address KPAGE to the page table.
    If WRITABLE is true, the user process may modify the page;