-;;;; detecting and handling exhaustion of memory (stack or heap)
+;;;; detecting and handling exhaustion of fundamental system resources
+;;;; (stack or heap)
;;;; This software is part of the SBCL system. See the README file for
;;;; more information.
(in-package "SB!KERNEL")
-;;; A native address on a 4-byte boundary can be thought of (and
-;;; passed around in Lisp code as) a FIXNUM. This function converts
-;;; from a byte address represented as an unsigned integer to such
-;;; a FIXNUM.
+;;; a soft limit on control stack overflow; the boundary beyond which
+;;; the control stack will be considered to've overflowed
;;;
-;;; FIXME: There should be some better place for this definition to
-;;; go. (Or a redundant definition might already exist. Especially
-;;; since this is essentially just a type pun, so there might be some
-;;; VOP or something which'd do it for us.)
-(eval-when (:compile-toplevel :load-toplevel :execute)
- (defun native-address-encoded-as-fixnum (native-address)
- (declare (type unsigned-byte native-address))
- (aver (zerop (logand native-address 3)))
- (let* (;; naive encoding
- (first-try (ash native-address -2))
- ;; final encoding
- (second-try
- (if (<= first-try sb!vm:*target-most-positive-fixnum*)
- ;; looks good
- first-try
- ;; When the naive encoding fails to make a FIXNUM
- ;; because the sign is wrong, subtracting *T-M-P-F*
- ;; should fix it.
- (- first-try sb!vm:*target-most-positive-fixnum*))))
- (aver (<= second-try sb!vm:*target-most-positive-fixnum*))
- second-try)))
-
-;;; a FIXNUM, to be interpreted as a native pointer, which serves
-;;; as a boundary to catch stack overflow
-;;;
-;;; When stack overflow is detected, this is to be bound to a new
-;;; value (allowing some more space for error handling) around the
-;;; call to ERROR.
+;;; When overflow is detected, this soft limit is to be bound to a new
+;;; value closer to the hard limit (allowing some more space for error
+;;; handling) around the call to ERROR, to allow space for the
+;;; error-handling logic.
;;;
;;; FIXME: Maybe (probably?) this should be in SB!VM. And maybe the
;;; size of the buffer zone should be set in src/compiler/cpu/parms.lisp
;;; instead of constantly 1Mb for all CPU architectures?
-(defvar *stack-exhaustion*
+(defvar *control-stack-exhaustion-sap*
;; (initialized in cold init)
)
(defun !exhaust-cold-init ()
- (setf *stack-exhaustion*
- #.(native-address-encoded-as-fixnum
- #!+stack-grows-downward (+ sb!vm:control-stack-start (expt 2 20))
- #!+stack-grows-upward (- sb!vm:control-stack-end (expt 2 20)))))
+ (let (;; initial difference between soft limit and hard limit
+ (initial-slack (expt 2 20)))
+ (setf *control-stack-exhaustion-sap*
+ (int-sap #!+stack-grows-downward-not-upward
+ (+ sb!vm:control-stack-start initial-slack)
+ #!-stack-grows-downward-not-upward
+ (- sb!vm:control-stack-end initial-slack)))))
;;; FIXME: Even though this is only called when (> SAFETY (MAX SPEED SPACE))
;;; it's still annoyingly wasteful for it to be a full function call.
;;; It should probably be a VOP calling an assembly routine or something
;;; like that.
(defun %detect-stack-exhaustion ()
- ;; FIXME: Check the stack pointer against *STACK-EXHAUSTION*, and if
- ;; out of range signal an error (in a context where *S-E* has been
- ;; rebound to give some space to let error handling code do its
- ;; thing without new exhaustion problems).
- (values))
+ (when (#!-stack-grows-downward-not-upward sap>=
+ #!+stack-grows-downward-not-upward sap<=
+ (current-sp)
+ *control-stack-exhaustion-sap*)
+ (let ((*control-stack-exhaustion-sap*
+ (revised-control-stack-exhaustion-sap)))
+ (warn "~@<ordinary control stack soft limit temporarily displaced to ~
+ allow possible interactive debugging~@:>")
+ (error "The system control stack was exhausted.")))
+ ;; FIXME: It'd be good to check other stacks (e.g. binding stack)
+ ;; here too.
+ )
+
+;;; Return a revised value for the *CONTROL-STACK-EXHAUSTION-SAP* soft
+;;; limit, allocating half the remaining space up to the hard limit in
+;;; order to allow interactive debugging to be used around the point
+;;; of a stack overflow failure without immediately failing again from
+;;; the (continuing) stack overflow.
+(defun revised-control-stack-exhaustion-sap ()
+ (let* ((old-slack
+ #!-stack-grows-downward-not-upward
+ (- sb!vm:control-stack-end
+ (sap-int *control-stack-exhaustion-sap*))
+ #!+stack-grows-downward-not-upward
+ (- (sap-int *control-stack-exhaustion-sap*)
+ sb!vm:control-stack-start))
+ (new-slack (ash old-slack -1)))
+ (int-sap #!-stack-grows-downward-not-upward
+ (- sb!vm:control-stack-end new-slack)
+ #!+stack-grows-downward-not-upward
+ (+ sb!vm:control-stack-start new-slack))))
projects / sbcl.git / blobdiff