feat: allow stack to grow for process up to 8MB in size

src/vm/stackgrowth.c

@@ -0,0 +1,38 @@
+#include <stdio.h>
+#include "stackgrowth.h"
+#include "threads/palloc.h"
+#include "threads/thread.h"
+#include "threads/vaddr.h"
+#include "userprog/pagedir.h"
+
+/* Validates a given address for being <=32 bytes away from the stack pointer or
+   above the stack */
+bool needs_new_page (void *addr, void *esp)
+{
+    return (is_user_vaddr (addr) &&
+            (uint32_t*)addr >= ((uint32_t*)esp - 32) &&
+                    ((PHYS_BASE - pg_round_down (addr))
+                                  <= MAX_STACK_SIZE));
+}
+
+/* Extends the stack by the necessary number of pages */
+bool grow_stack (void *addr)
+{
+  struct thread *t = thread_current ();
+  void *last_page = pg_round_down (addr);
+
+  uint8_t *new_page = palloc_get_page (PAL_USER | PAL_ZERO);
+  if ( new_page == NULL)
+    return false;
+
+  bool added_page = pagedir_get_page (t->pagedir, last_page) == NULL
+                    && pagedir_set_page (t->pagedir, last_page, new_page, true);
+
+  if (!added_page) {
+    palloc_free_page (new_page);
+    return false;
+  }
+  return true;
+
+
+}