anchor.diff:  (defparameter *step-special-functions*
     '(cons cons-in-area
       mezzano.runtime::%allocate-object
  -    mezzano.supervisor::%call-on-wired-stack-without-interrupts))
  +    mezzano.supervisor::%call-on-wired-stack-without-interrupts
  +    mezzano.supervisor::call-with-mutex))
   
   (defun single-step-wrapper (&rest args &closure call-me)
     (declare (dynamic-extent args))
  
positive.code:          (prev-fn nil))
      (mezzano.supervisor::stop-thread thread)
      (setf stopped t)
      (loop
         (when (and (zerop (mod (incf instructions-stepped) 1000))
                    (y-or-n-p "Thread has run for ~D instructions. Stop?" instructions-stepped))
           (mezzano.supervisor:terminate-thread thread)
           (mezzano.supervisor::resume-thread thread)
           (return))
         (when (eql (mezzano.supervisor:thread-state thread) :dead)
           (format t "Thread has died.~%")
           (return))
         (dump-thread-state thread)
         (safe-single-step-thread thread)
         (let* ((rip (mezzano.supervisor:thread-state-rip thread))
                (fn (return-address-to-function rip)))
           (when (and prev-fn
                      (not (eql fn prev-fn)))
             (cond ((eql rip (%object-ref-unsigned-byte-64 fn +function-entry-point+))
                    (format t "Entered function ~S with arguments ~:S.~%" fn (fetch-thread-function-arguments thread)))
                   (t
                    (format t "Returning from function ~S to ~S with results ~:S.~%"
                            prev-fn fn (fetch-thread-return-values thread)))))
           (setf prev-fn fn)))))
  
negative.code:          (format t " rip: ~8,'0X~%" (sys.int::memref-unsigned-byte-64 (mezzano.supervisor:thread-state-rsp thread) 0))))
    (values))
  
  (defun trace-execution (function &key full-dump run-forever)
    (check-type function function)
    (let* ((next-stop-boundary 1000)
           (stopped nil)
           (thread (mezzano.supervisor:make-thread
                    (lambda ()
                      (loop
  