Fix: Magic number in stackgrowth.c

src/vm/stackgrowth.c

@@ -5,14 +5,16 @@
 #include "threads/vaddr.h"
 #include "userprog/pagedir.h"
 
+#define MAX_STACK_ACCESS_DIST 32
+
 /* 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));
+            (uint32_t*)addr >= ((uint32_t*)esp - MAX_STACK_ACCESS_DIST) &&
+            ((PHYS_BASE - pg_round_down (addr))
+                          <= MAX_STACK_SIZE));
 }
 
 /* Extends the stack by the necessary number of pages */