1.0.4.33: check that context is not a null-alien

[sbcl.git] / src / code / debug-int.lisp

diff --git a/src/code/debug-int.lisp b/src/code/debug-int.lisp
index 80b08ce..fbec1a2 100644 (file)
--- a/src/code/debug-int.lisp
+++ b/src/code/debug-int.lisp
@@ -526,11 +526,11 @@
     #!-stack-grows-downward-not-upward
     (and (sap< x (current-sp))
          (sap<= control-stack-start x)
-         (zerop (logand (sap-int x) #b11)))
+         (zerop (logand (sap-int x) sb!vm:fixnum-tag-mask)))
     #!+stack-grows-downward-not-upward
     (and (sap>= x (current-sp))
          (sap> control-stack-end x)
-         (zerop (logand (sap-int x) #b11)))))
+         (zerop (logand (sap-int x) sb!vm:fixnum-tag-mask)))))
 
 (declaim (inline component-ptr-from-pc))
 (sb!alien:define-alien-routine component-ptr-from-pc (system-area-pointer)
@@ -654,12 +654,29 @@
 (defun descriptor-sap (x)
   (int-sap (get-lisp-obj-address x)))
 
+(defun nth-interrupt-context (n)
+  (declare (type (unsigned-byte 32) n)
+           (optimize (speed 3) (safety 0)))
+  (sb!alien:sap-alien (sb!vm::current-thread-offset-sap
+                       (+ sb!vm::thread-interrupt-contexts-offset n))
+                      (* os-context-t)))
+
 ;;; Return the top frame of the control stack as it was before calling
 ;;; this function.
 (defun top-frame ()
   (/noshow0 "entering TOP-FRAME")
-  (multiple-value-bind (fp pc) (%caller-frame-and-pc)
-    (compute-calling-frame (descriptor-sap fp) pc nil)))
+  ;; check to see if we can get the context by calling
+  ;; nth-interrupt-context, otherwise use the (%caller-frame-and-pc
+  ;; vop).
+  (let ((context (nth-interrupt-context 0)))
+    (if (and context
+             (not (sb!alien:null-alien context)))
+        (compute-calling-frame
+         (int-sap (sb!vm:context-register context
+                                          sb!vm::cfp-offset))
+         (context-pc context) nil)
+        (multiple-value-bind (fp pc) (%caller-frame-and-pc)
+          (compute-calling-frame (descriptor-sap fp) pc nil)))))
 
 ;;; Flush all of the frames above FRAME, and renumber all the frames
 ;;; below FRAME.
@@ -861,13 +878,6 @@
                              (if up-frame (1+ (frame-number up-frame)) 0)
                              escaped)))))
 
-(defun nth-interrupt-context (n)
-  (declare (type (unsigned-byte 32) n)
-           (optimize (speed 3) (safety 0)))
-  (sb!alien:sap-alien (sb!vm::current-thread-offset-sap
-                       (+ sb!vm::thread-interrupt-contexts-offset n))
-                      (* os-context-t)))
-
 #!+(or x86 x86-64)
 (defun find-escaped-frame (frame-pointer)
   (declare (type system-area-pointer frame-pointer))