1 ;;;; detecting and handling exhaustion of fundamental system resources
4 ;;;; This software is part of the SBCL system. See the README file for
7 ;;;; This software is derived from the CMU CL system, which was
8 ;;;; written at Carnegie Mellon University and released into the
9 ;;;; public domain. The software is in the public domain and is
10 ;;;; provided with absolutely no warranty. See the COPYING and CREDITS
11 ;;;; files for more information.
13 (in-package "SB!KERNEL")
15 ;;; a soft limit on stack overflow; the boundary beyond which the
16 ;;; control stack will be considered to've overflowed
18 ;;; When stack overflow is detected, this soft limit is to be bound to
19 ;;; a new value closer to the hard limit (allowing some more space for
20 ;;; error handling) around the call to ERROR.
22 ;;; FIXME: Maybe (probably?) this should be in SB!VM. And maybe the
23 ;;; size of the buffer zone should be set in src/compiler/cpu/parms.lisp
24 ;;; instead of constantly 1Mb for all CPU architectures?
25 (defvar *stack-exhaustion-sap*
26 ;; (initialized in cold init)
28 (defun !exhaust-cold-init ()
29 (let (;; initial difference between soft limit and hard limit
30 (initial-slack (expt 2 20)))
31 (setf *stack-exhaustion-sap*
32 (int-sap #!+stack-grows-downward (+ sb!vm:control-stack-start
34 #!+stack-grows-upward (- sb!vm:control-stack-end
37 ;;; FIXME: Even though this is only called when (> SAFETY (MAX SPEED SPACE))
38 ;;; it's still annoyingly wasteful for it to be a full function call.
39 ;;; It should probably be a VOP calling an assembly routine or something
41 (defun %detect-stack-exhaustion ()
42 (when (#!+stack-grows-upward sap>=
43 #!+stack-grows-downward sap<=
45 *stack-exhaustion-sap*)
46 (let ((*stack-exhaustion-sap* (revised-stack-exhaustion-sap)))
47 (warn "~@<ordinary control stack soft limit temporarily displaced to ~
48 allow possible interactive debugging~@:>")
49 (error "The system control stack was exhausted."))))
51 ;;; Return a revised value for the *STACK-EXHAUSTION-SAP* soft limit,
52 ;;; allocating half the remaining space up to the hard limit in order
53 ;;; to allow interactive debugging to be used around the point of a
54 ;;; stack overflow failure without immediately failing again from the
55 ;;; (continuing) stack overflow.
56 (defun revised-stack-exhaustion-sap ()
58 #!+stack-grows-upward (- sb!vm:control-stack-end
59 (sap-int *stack-exhaustion-sap*))
60 #!+stack-grows-downward (- (sap-int *stack-exhaustion-sap*)
61 sb!vm:control-stack-start))
62 (new-slack (ash old-slack -1)))
64 #!+stack-grows-upward (- sb!vm:control-stack-end new-slack)
65 #!+stack-grows-downward (+ sb!vm:control-stack-start new-slack))))