没有libc6-dbg的符号如何查找main_arena

int
__malloc_trim (size_t s)
{
  int result = 0;
  if (__malloc_initialized < 0)
    ptmalloc_init ();
  mstate ar_ptr = &main_arena;
  do
    {
      __libc_lock_lock (ar_ptr->mutex);
      result |= mtrim (ar_ptr, s);
      __libc_lock_unlock (ar_ptr->mutex);
      ar_ptr = ar_ptr->next;
    }
  while (ar_ptr != &main_arena);
  return result;
}