(in-package "SB!UNIX")
(defmacro with-interrupt-bindings (&body body)
- (with-unique-names (empty)
- `(let*
- ;; KLUDGE: Whatever is on the PCL stacks before the interrupt
- ;; handler runs doesn't really matter, since we're not on the
- ;; same call stack, really -- and if we don't bind these (esp.
- ;; the cache one) we can get a bogus metacircle if an interrupt
- ;; handler calls a GF that was being computed when the interrupt
- ;; hit.
- ((sb!pcl::*cache-miss-values-stack* nil)
- (sb!pcl::*dfun-miss-gfs-on-stack* nil)
- ;; Unless we do this, ADJUST-ARRAY and SORT would need to
- ;; disable interrupts.
- (,empty (vector))
- (sb!impl::*zap-array-data-temp* ,empty)
- (sb!impl::*merge-sort-temp-vector* ,empty))
- ,@body)))
+ `(let*
+ ;; KLUDGE: Whatever is on the PCL stacks before the interrupt
+ ;; handler runs doesn't really matter, since we're not on the
+ ;; same call stack, really -- and if we don't bind these (esp.
+ ;; the cache one) we can get a bogus metacircle if an interrupt
+ ;; handler calls a GF that was being computed when the interrupt
+ ;; hit.
+ ((sb!pcl::*cache-miss-values-stack* nil)
+ (sb!pcl::*dfun-miss-gfs-on-stack* nil))
+ ,@body))
+
+;;; Evaluate CLEANUP-FORMS iff PROTECTED-FORM does a non-local exit.
+(defmacro nlx-protect (protected-form &rest cleanup-froms)
+ (with-unique-names (completep)
+ `(let ((,completep nil))
+ (without-interrupts
+ (unwind-protect
+ (progn
+ (allow-with-interrupts
+ ,protected-form)
+ (setq ,completep t))
+ (unless ,completep
+ ,@cleanup-froms))))))
(defun invoke-interruption (function)
(without-interrupts
- (with-interrupt-bindings
- ;; Reset signal mask: the C-side handler has blocked all
- ;; deferrable interrupts before arranging return to lisp. This is
- ;; safe because we can't get a pending interrupt before we unblock
- ;; signals.
- (unblock-deferrable-signals)
- (let ((sb!debug:*stack-top-hint*
- (nth-value 1 (sb!kernel:find-interrupted-name-and-frame))))
- (allow-with-interrupts (funcall function))))))
+ ;; Reset signal mask: the C-side handler has blocked all
+ ;; deferrable signals before funcalling into lisp. They are to be
+ ;; unblocked the first time interrupts are enabled. With this
+ ;; mechanism there are no extra frames on the stack from a
+ ;; previous signal handler when the next signal is delivered
+ ;; provided there is no WITH-INTERRUPTS.
+ (let ((*unblock-deferrables-on-enabling-interrupts-p* t)
+ (sb!debug:*stack-top-hint* (or sb!debug:*stack-top-hint* 'invoke-interruption)))
+ (with-interrupt-bindings
+ (sb!thread::without-thread-waiting-for (:already-without-interrupts t)
+ (allow-with-interrupts
+ (nlx-protect (funcall function)
+ ;; We've been running with deferrables
+ ;; blocked in Lisp called by a C signal
+ ;; handler. If we return normally the sigmask
+ ;; in the interrupted context is restored.
+ ;; However, if we do an nlx the operating
+ ;; system will not restore it for us.
+ (when *unblock-deferrables-on-enabling-interrupts-p*
+ ;; This means that storms of interrupts
+ ;; doing an nlx can still run out of stack.
+ (unblock-deferrable-signals)))))))))
(defmacro in-interruption ((&key) &body body)
#!+sb-doc
;;; doing things the SBCL way and moving this kind of C-level work
;;; down to C wrapper functions.)
-(sb!alien:define-alien-routine "unblock_deferrable_signals" sb!alien:void)
-(sb!alien:define-alien-routine "unblock_gc_signals" sb!alien:void)
+(declaim (inline %unblock-deferrable-signals %unblock-gc-signals))
+(sb!alien:define-alien-routine ("unblock_deferrable_signals"
+ %unblock-deferrable-signals)
+ sb!alien:void
+ (where sb!alien:unsigned-long)
+ (old sb!alien:unsigned-long))
+#!-sb-safepoint
+(sb!alien:define-alien-routine ("unblock_gc_signals" %unblock-gc-signals)
+ sb!alien:void
+ (where sb!alien:unsigned-long)
+ (old sb!alien:unsigned-long))
+
+(defun unblock-deferrable-signals ()
+ (%unblock-deferrable-signals 0 0))
+
+#!-sb-safepoint
+(defun unblock-gc-signals ()
+ (%unblock-gc-signals 0 0))
\f
;;;; C routines that actually do all the work of establishing signal handlers
(sb!alien:define-alien-routine ("install_handler" install-handler)
sb!alien:unsigned-long
(signal sb!alien:int)
- (handler sb!alien:unsigned-long))
+ (handler sb!alien:unsigned-long)
+ (synchronous boolean))
;;;; interface to enabling and disabling signal handlers
-(defun enable-interrupt (signal handler)
+;;; Note on the SYNCHRONOUS argument: On builds without pseudo-atomic,
+;;; we have no way of knowing whether interrupted code was in an
+;;; allocation sequence, and cannot delay signals until after
+;;; allocation. Any signal that can occur asynchronously must be
+;;; considered unsafe for immediate execution, and the invocation of its
+;;; lisp handler will get delayed into a newly spawned signal handler
+;;; thread. However, there are signals which we must handle
+;;; immediately, because they occur synchonously (hence the boolean flag
+;;; SYNCHRONOUS to this function), luckily implying that the signal
+;;; happens only in specific places (illegal instructions, floating
+;;; point instructions, certain system calls), hopefully ruling out the
+;;; possibility that we would trigger it during allocation.
+
+(defun enable-interrupt (signal handler &key synchronous)
(declare (type (or function fixnum (member :default :ignore)) handler))
(/show0 "enable-interrupt")
(flet ((run-handler (&rest args)
(:ignore sig-ign)
(t
(sb!kernel:get-lisp-obj-address
- #'run-handler))))))
+ #'run-handler)))
+ synchronous)))
(cond ((= result sig-dfl) :default)
((= result sig-ign) :ignore)
(t (the (or function fixnum)
(defun ignore-interrupt (signal)
(enable-interrupt signal :ignore))
\f
+;;;; Support for signal handlers which aren't.
+;;;;
+;;;; On safepoint builds, user-defined Lisp signal handlers do not run
+;;;; in the handler for their signal, because we have no pseudo atomic
+;;;; mechanism to prevent handlers from hitting during allocation.
+;;;; Rather, the signal spawns off a fresh native thread, which calls
+;;;; into lisp with a fake context through this callback:
+
+#!+(and sb-safepoint-strictly (not win32))
+(defun signal-handler-callback (run-handler signal args)
+ (sb!thread::initial-thread-function-trampoline
+ (sb!thread::make-signal-handling-thread :name "signal handler"
+ :signal-number signal)
+ nil (lambda ()
+ (let* ((info (sb!sys:sap-ref-sap args 0))
+ (context (sb!sys:sap-ref-sap args sb!vm:n-word-bytes)))
+ (funcall run-handler signal info context)))
+ nil nil nil nil))
+
+\f
;;;; default LISP signal handlers
;;;;
;;;; Most of these just call ERROR to report the presence of the signal.
#!-linux
(define-signal-handler sigemt-handler "SIGEMT")
(define-signal-handler sigbus-handler "bus error")
-(define-signal-handler sigsegv-handler "segmentation violation")
#!-linux
(define-signal-handler sigsys-handler "bad argument to a system call")
(declare (type system-area-pointer context))
(/show "in Lisp-level SIGINT handler" (sap-int context))
(flet ((interrupt-it ()
+ ;; This seems wrong to me on multi-threaded builds. The
+ ;; closed-over signal context belongs to a SIGINT handler.
+ ;; But this function gets run through INTERRUPT-THREAD,
+ ;; i.e. in in a SIGPIPE handler, at a different point in time
+ ;; or even a different thread. How do we know that the
+ ;; SIGINT's context structure from the other thread is still
+ ;; alive and meaningful? Why do we care? If we even need
+ ;; the context and PC, shouldn't they come from the SIGPIPE's
+ ;; context? --DFL
(with-alien ((context (* os-context-t) context))
- (%break 'sigint 'interactive-interrupt
- :context context
- :address (sap-int (sb!vm:context-pc context))))))
+ (with-interrupts
+ (let ((int (make-condition 'interactive-interrupt
+ :context context
+ :address (sap-int (sb!vm:context-pc context)))))
+ ;; First SIGNAL, so that handlers can run.
+ (signal int)
+ ;; Then enter the debugger like BREAK.
+ (%break 'sigint int))))))
+ #!+sb-safepoint
+ (let ((target (sb!thread::foreground-thread)))
+ ;; Note that INTERRUPT-THREAD on *CURRENT-THREAD* doesn't actually
+ ;; interrupt right away, because deferrables are blocked. Rather,
+ ;; the kernel would arrange for the SIGPIPE to hit when the SIGINT
+ ;; handler is done. However, on safepoint builds, we don't use
+ ;; SIGPIPE and lack an appropriate mechanism to handle pending
+ ;; thruptions upon exit from signal handlers (and this situation is
+ ;; unlike WITHOUT-INTERRUPTS, which handles pending interrupts
+ ;; explicitly at the end). Only as long as safepoint builds pretend
+ ;; to cooperate with signals -- that is, as long as SIGINT-HANDLER
+ ;; is used at all -- detect this situation and work around it.
+ (if (eq target sb!thread:*current-thread*)
+ (interrupt-it)
+ (sb!thread:interrupt-thread target #'interrupt-it)))
+ #!-sb-safepoint
(sb!thread:interrupt-thread (sb!thread::foreground-thread)
#'interrupt-it)))
+#!-sb-wtimer
(defun sigalrm-handler (signal info context)
(declare (ignore signal info context))
(declare (type system-area-pointer context))
(defun sigterm-handler (signal code context)
(declare (ignore signal code context))
- (sb!thread::terminate-session)
- (sb!ext:quit))
+ (sb!ext:exit))
+
+#!-sb-thruption
+;;; SIGPIPE is not used in SBCL for its original purpose, instead it's
+;;; for signalling a thread that it should look at its interruption
+;;; queue. The handler (RUN_INTERRUPTION) just returns if there is
+;;; nothing to do so it's safe to receive spurious SIGPIPEs coming
+;;; from the kernel.
+(defun sigpipe-handler (signal code context)
+ (declare (ignore signal code context))
+ (sb!thread::run-interruption))
+
+;;; the handler for SIGCHLD signals for RUN-PROGRAM
+(defun sigchld-handler (signal code context)
+ (declare (ignore signal code context))
+ (sb!impl::get-processes-status-changes))
(defun sb!kernel:signal-cold-init-or-reinit ()
#!+sb-doc
"Enable all the default signals that Lisp knows how to deal with."
(enable-interrupt sigint #'sigint-handler)
(enable-interrupt sigterm #'sigterm-handler)
- (enable-interrupt sigill #'sigill-handler)
+ (enable-interrupt sigill #'sigill-handler :synchronous t)
#!-linux
(enable-interrupt sigemt #'sigemt-handler)
- (enable-interrupt sigfpe #'sb!vm:sigfpe-handler)
- (enable-interrupt sigbus #'sigbus-handler)
- (enable-interrupt sigsegv #'sigsegv-handler)
+ (enable-interrupt sigfpe #'sb!vm:sigfpe-handler :synchronous t)
+ (enable-interrupt sigbus #'sigbus-handler :synchronous t)
#!-linux
- (enable-interrupt sigsys #'sigsys-handler)
- (ignore-interrupt sigpipe)
+ (enable-interrupt sigsys #'sigsys-handler :synchronous t)
+ #!-sb-wtimer
(enable-interrupt sigalrm #'sigalrm-handler)
+ #!-sb-thruption
+ (enable-interrupt sigpipe #'sigpipe-handler)
+ (enable-interrupt sigchld #'sigchld-handler)
#!+hpux (ignore-interrupt sigxcpu)
- (unblock-gc-signals)
+ #!-sb-safepoint (unblock-gc-signals)
(unblock-deferrable-signals)
(values))
\f
projects / sbcl.git / blobdiff