2 * interrupt-handling magic
6 * This software is part of the SBCL system. See the README file for
9 * This software is derived from the CMU CL system, which was
10 * written at Carnegie Mellon University and released into the
11 * public domain. The software is in the public domain and is
12 * provided with absolutely no warranty. See the COPYING and CREDITS
13 * files for more information.
17 /* As far as I can tell, what's going on here is:
19 * In the case of most signals, when Lisp asks us to handle the
20 * signal, the outermost handler (the one actually passed to UNIX) is
21 * either interrupt_handle_now(..) or maybe_now_maybe_later(..).
22 * In that case, the Lisp-level handler is stored in interrupt_handlers[..]
23 * and interrupt_low_level_handlers[..] is cleared.
25 * However, some signals need special handling, e.g.
27 * o the SIGSEGV (for e.g. Linux) or SIGBUS (for e.g. FreeBSD) used by the
28 * garbage collector to detect violations of write protection,
29 * because some cases of such signals (e.g. GC-related violations of
30 * write protection) are handled at C level and never passed on to
31 * Lisp. For such signals, we still store any Lisp-level handler
32 * in interrupt_handlers[..], but for the outermost handle we use
33 * the value from interrupt_low_level_handlers[..], instead of the
34 * ordinary interrupt_handle_now(..) or interrupt_handle_later(..).
36 * o the SIGTRAP (Linux/Alpha) which Lisp code uses to handle breakpoints,
37 * pseudo-atomic sections, and some classes of error (e.g. "function
38 * not defined"). This never goes anywhere near the Lisp handlers at all.
39 * See runtime/alpha-arch.c and code/signal.lisp
41 * - WHN 20000728, dan 20010128 */
49 #include <sys/types.h>
50 #ifndef LISP_FEATURE_WIN32
58 #include "interrupt.h"
66 #include "genesis/fdefn.h"
67 #include "genesis/simple-fun.h"
68 #include "genesis/cons.h"
72 static void run_deferred_handler(struct interrupt_data *data, void *v_context);
73 #ifndef LISP_FEATURE_WIN32
74 static void store_signal_data_for_later (struct interrupt_data *data,
75 void *handler, int signal,
77 os_context_t *context);
78 boolean interrupt_maybe_gc_int(int signal, siginfo_t *info, void *v_context);
81 sigaddset_deferrable(sigset_t *s)
85 sigaddset(s, SIGQUIT);
86 sigaddset(s, SIGPIPE);
87 sigaddset(s, SIGALRM);
89 sigaddset(s, SIGTSTP);
90 sigaddset(s, SIGCHLD);
92 sigaddset(s, SIGXCPU);
93 sigaddset(s, SIGXFSZ);
94 sigaddset(s, SIGVTALRM);
95 sigaddset(s, SIGPROF);
96 sigaddset(s, SIGWINCH);
98 #if !((defined(LISP_FEATURE_DARWIN) || defined(LISP_FEATURE_FREEBSD)) && defined(LISP_FEATURE_SB_THREAD))
99 sigaddset(s, SIGUSR1);
100 sigaddset(s, SIGUSR2);
103 #ifdef LISP_FEATURE_SB_THREAD
104 sigaddset(s, SIG_INTERRUPT_THREAD);
109 sigaddset_blockable(sigset_t *s)
111 sigaddset_deferrable(s);
112 #ifdef LISP_FEATURE_SB_THREAD
113 #ifdef SIG_RESUME_FROM_GC
114 sigaddset(s, SIG_RESUME_FROM_GC);
116 sigaddset(s, SIG_STOP_FOR_GC);
120 /* initialized in interrupt_init */
121 static sigset_t deferrable_sigset;
122 static sigset_t blockable_sigset;
126 check_blockables_blocked_or_lose()
128 #ifndef LISP_FEATURE_WIN32
129 /* Get the current sigmask, by blocking the empty set. */
130 sigset_t empty,current;
133 thread_sigmask(SIG_BLOCK, &empty, ¤t);
134 for(i = 1; i < NSIG; i++) {
135 if (sigismember(&blockable_sigset, i) && !sigismember(¤t, i))
136 lose("blockable signal %d not blocked\n",i);
142 check_interrupts_enabled_or_lose(os_context_t *context)
144 struct thread *thread=arch_os_get_current_thread();
145 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL)
146 lose("interrupts not enabled\n");
148 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
149 (!foreign_function_call_active) &&
151 arch_pseudo_atomic_atomic(context))
152 lose ("in pseudo atomic section\n");
155 /* When we catch an internal error, should we pass it back to Lisp to
156 * be handled in a high-level way? (Early in cold init, the answer is
157 * 'no', because Lisp is still too brain-dead to handle anything.
158 * After sufficient initialization has been completed, the answer
160 boolean internal_errors_enabled = 0;
162 #ifndef LISP_FEATURE_WIN32
163 static void (*interrupt_low_level_handlers[NSIG]) (int, siginfo_t*, void*);
165 union interrupt_handler interrupt_handlers[NSIG];
167 /* At the toplevel repl we routinely call this function. The signal
168 * mask ought to be clear anyway most of the time, but may be non-zero
169 * if we were interrupted e.g. while waiting for a queue. */
172 reset_signal_mask(void)
174 #ifndef LISP_FEATURE_WIN32
177 thread_sigmask(SIG_SETMASK,&new,0);
182 block_blockable_signals(void)
184 #ifndef LISP_FEATURE_WIN32
185 thread_sigmask(SIG_BLOCK, &blockable_sigset, 0);
191 * utility routines used by various signal handlers
195 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
197 #ifndef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
201 /* Build a fake stack frame or frames */
203 current_control_frame_pointer =
204 (lispobj *)(unsigned long)
205 (*os_context_register_addr(context, reg_CSP));
206 if ((lispobj *)(unsigned long)
207 (*os_context_register_addr(context, reg_CFP))
208 == current_control_frame_pointer) {
209 /* There is a small window during call where the callee's
210 * frame isn't built yet. */
211 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
212 == FUN_POINTER_LOWTAG) {
213 /* We have called, but not built the new frame, so
214 * build it for them. */
215 current_control_frame_pointer[0] =
216 *os_context_register_addr(context, reg_OCFP);
217 current_control_frame_pointer[1] =
218 *os_context_register_addr(context, reg_LRA);
219 current_control_frame_pointer += 8;
220 /* Build our frame on top of it. */
221 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
224 /* We haven't yet called, build our frame as if the
225 * partial frame wasn't there. */
226 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
229 /* We can't tell whether we are still in the caller if it had to
230 * allocate a stack frame due to stack arguments. */
231 /* This observation provoked some past CMUCL maintainer to ask
232 * "Can anything strange happen during return?" */
235 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
238 current_control_stack_pointer = current_control_frame_pointer + 8;
240 current_control_frame_pointer[0] = oldcont;
241 current_control_frame_pointer[1] = NIL;
242 current_control_frame_pointer[2] =
243 (lispobj)(*os_context_register_addr(context, reg_CODE));
247 /* Stores the context for gc to scavange and builds fake stack
250 fake_foreign_function_call(os_context_t *context)
253 struct thread *thread=arch_os_get_current_thread();
255 /* context_index incrementing must not be interrupted */
256 check_blockables_blocked_or_lose();
258 /* Get current Lisp state from context. */
260 dynamic_space_free_pointer =
261 (lispobj *)(unsigned long)
262 (*os_context_register_addr(context, reg_ALLOC));
263 /* fprintf(stderr,"dynamic_space_free_pointer: %p\n", dynamic_space_free_pointer); */
264 #if defined(LISP_FEATURE_ALPHA)
265 if ((long)dynamic_space_free_pointer & 1) {
266 lose("dead in fake_foreign_function_call, context = %x\n", context);
271 current_binding_stack_pointer =
272 (lispobj *)(unsigned long)
273 (*os_context_register_addr(context, reg_BSP));
276 build_fake_control_stack_frames(thread,context);
278 /* Do dynamic binding of the active interrupt context index
279 * and save the context in the context array. */
281 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
283 if (context_index >= MAX_INTERRUPTS) {
284 lose("maximum interrupt nesting depth (%d) exceeded\n", MAX_INTERRUPTS);
287 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
288 make_fixnum(context_index + 1),thread);
290 thread->interrupt_contexts[context_index] = context;
292 /* no longer in Lisp now */
293 foreign_function_call_active = 1;
296 /* blocks all blockable signals. If you are calling from a signal handler,
297 * the usual signal mask will be restored from the context when the handler
298 * finishes. Otherwise, be careful */
300 undo_fake_foreign_function_call(os_context_t *context)
302 struct thread *thread=arch_os_get_current_thread();
303 /* Block all blockable signals. */
304 block_blockable_signals();
306 /* going back into Lisp */
307 foreign_function_call_active = 0;
309 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
313 /* Put the dynamic space free pointer back into the context. */
314 *os_context_register_addr(context, reg_ALLOC) =
315 (unsigned long) dynamic_space_free_pointer
316 | (*os_context_register_addr(context, reg_ALLOC)
319 ((unsigned long)(*os_context_register_addr(context, reg_ALLOC)) & ~LOWTAG_MASK)
320 | ((unsigned long) dynamic_space_free_pointer & LOWTAG_MASK);
325 /* a handler for the signal caused by execution of a trap opcode
326 * signalling an internal error */
328 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
333 fake_foreign_function_call(context);
335 if (!internal_errors_enabled) {
336 describe_internal_error(context);
337 /* There's no good way to recover from an internal error
338 * before the Lisp error handling mechanism is set up. */
339 lose("internal error too early in init, can't recover\n");
342 /* Allocate the SAP object while the interrupts are still
344 context_sap = alloc_sap(context);
346 #ifndef LISP_FEATURE_WIN32
347 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
350 SHOW("in interrupt_internal_error");
352 /* Display some rudimentary debugging information about the
353 * error, so that even if the Lisp error handler gets badly
354 * confused, we have a chance to determine what's going on. */
355 describe_internal_error(context);
357 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
358 continuable ? T : NIL);
360 undo_fake_foreign_function_call(context); /* blocks signals again */
362 arch_skip_instruction(context);
366 interrupt_handle_pending(os_context_t *context)
368 struct thread *thread;
369 struct interrupt_data *data;
371 FSHOW_SIGNAL((stderr, "/entering interrupt_handle_pending\n"));
373 check_blockables_blocked_or_lose();
374 thread=arch_os_get_current_thread();
375 data=thread->interrupt_data;
377 /* If pseudo_atomic_interrupted is set then the interrupt is going
378 * to be handled now, ergo it's safe to clear it. */
379 arch_clear_pseudo_atomic_interrupted(context);
381 if (SymbolValue(GC_INHIBIT,thread)==NIL) {
382 #ifdef LISP_FEATURE_SB_THREAD
383 if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
384 /* another thread has already initiated a gc, this attempt
385 * might as well be cancelled */
386 SetSymbolValue(GC_PENDING,NIL,thread);
387 SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
388 sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
391 if (SymbolValue(GC_PENDING,thread) != NIL) {
392 /* GC_PENDING is cleared in SUB-GC, or if another thread
393 * is doing a gc already we will get a SIG_STOP_FOR_GC and
394 * that will clear it. */
395 interrupt_maybe_gc_int(0,NULL,context);
397 check_blockables_blocked_or_lose();
400 /* we may be here only to do the gc stuff, if interrupts are
401 * enabled run the pending handler */
402 if (!((SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) ||
404 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
405 (!foreign_function_call_active) &&
407 arch_pseudo_atomic_atomic(context)))) {
409 /* There may be no pending handler, because it was only a gc
410 * that had to be executed or because pseudo atomic triggered
411 * twice for a single interrupt. For the interested reader,
412 * that may happen if an interrupt hits after the interrupted
413 * flag is cleared but before pseduo-atomic is set and a
414 * pseudo atomic is interrupted in that interrupt. */
415 if (data->pending_handler) {
417 /* If we're here as the result of a pseudo-atomic as opposed
418 * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
419 * NIL, because maybe_defer_handler sets
420 * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
421 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
423 #ifndef LISP_FEATURE_WIN32
424 /* restore the saved signal mask from the original signal (the
425 * one that interrupted us during the critical section) into the
426 * os_context for the signal we're currently in the handler for.
427 * This should ensure that when we return from the handler the
428 * blocked signals are unblocked */
429 sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
431 sigemptyset(&data->pending_mask);
433 /* This will break on sparc linux: the deferred handler really wants
434 * to be called with a void_context */
435 run_deferred_handler(data,(void *)context);
441 * the two main signal handlers:
442 * interrupt_handle_now(..)
443 * maybe_now_maybe_later(..)
445 * to which we have added interrupt_handle_now_handler(..). Why?
446 * Well, mostly because the SPARC/Linux platform doesn't quite do
447 * signals the way we want them done. The third argument in the
448 * handler isn't filled in by the kernel properly, so we fix it up
449 * ourselves in the arch_os_get_context(..) function; however, we only
450 * want to do this when we first hit the handler, and not when
451 * interrupt_handle_now(..) is being called from some other handler
452 * (when the fixup will already have been done). -- CSR, 2002-07-23
456 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
458 os_context_t *context = (os_context_t*)void_context;
459 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
460 boolean were_in_lisp;
462 union interrupt_handler handler;
464 check_blockables_blocked_or_lose();
467 #ifndef LISP_FEATURE_WIN32
468 if (sigismember(&deferrable_sigset,signal))
469 check_interrupts_enabled_or_lose(context);
472 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
473 /* Under Linux on some architectures, we appear to have to restore
474 the FPU control word from the context, as after the signal is
475 delivered we appear to have a null FPU control word. */
476 os_restore_fp_control(context);
480 handler = interrupt_handlers[signal];
482 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
486 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
487 were_in_lisp = !foreign_function_call_active;
491 fake_foreign_function_call(context);
494 FSHOW_SIGNAL((stderr,
495 "/entering interrupt_handle_now(%d, info, context)\n",
498 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
500 /* This can happen if someone tries to ignore or default one
501 * of the signals we need for runtime support, and the runtime
502 * support decides to pass on it. */
503 lose("no handler for signal %d in interrupt_handle_now(..)\n", signal);
505 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
506 /* Once we've decided what to do about contexts in a
507 * return-elsewhere world (the original context will no longer
508 * be available; should we copy it or was nobody using it anyway?)
509 * then we should convert this to return-elsewhere */
511 /* CMUCL comment said "Allocate the SAPs while the interrupts
512 * are still disabled.". I (dan, 2003.08.21) assume this is
513 * because we're not in pseudoatomic and allocation shouldn't
514 * be interrupted. In which case it's no longer an issue as
515 * all our allocation from C now goes through a PA wrapper,
516 * but still, doesn't hurt.
518 * Yeah, but non-gencgc platforms don't really wrap allocation
519 * in PA. MG - 2005-08-29 */
521 lispobj info_sap,context_sap = alloc_sap(context);
522 info_sap = alloc_sap(info);
523 /* Leave deferrable signals blocked, the handler itself will
524 * allow signals again when it sees fit. */
525 #ifdef LISP_FEATURE_SB_THREAD
528 sigemptyset(&unblock);
529 sigaddset(&unblock, SIG_STOP_FOR_GC);
530 #ifdef SIG_RESUME_FROM_GC
531 sigaddset(&unblock, SIG_RESUME_FROM_GC);
533 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
537 FSHOW_SIGNAL((stderr,"/calling Lisp-level handler\n"));
539 funcall3(handler.lisp,
545 FSHOW_SIGNAL((stderr,"/calling C-level handler\n"));
547 #ifndef LISP_FEATURE_WIN32
548 /* Allow signals again. */
549 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
552 (*handler.c)(signal, info, void_context);
555 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
559 undo_fake_foreign_function_call(context); /* block signals again */
562 FSHOW_SIGNAL((stderr,
563 "/returning from interrupt_handle_now(%d, info, context)\n",
567 /* This is called at the end of a critical section if the indications
568 * are that some signal was deferred during the section. Note that as
569 * far as C or the kernel is concerned we dealt with the signal
570 * already; we're just doing the Lisp-level processing now that we
573 run_deferred_handler(struct interrupt_data *data, void *v_context) {
574 /* The pending_handler may enable interrupts and then another
575 * interrupt may hit, overwrite interrupt_data, so reset the
576 * pending handler before calling it. Trust the handler to finish
577 * with the siginfo before enabling interrupts. */
578 void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
579 os_context_t *context = arch_os_get_context(&v_context);
581 data->pending_handler=0;
582 (*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
585 #ifndef LISP_FEATURE_WIN32
587 maybe_defer_handler(void *handler, struct interrupt_data *data,
588 int signal, siginfo_t *info, os_context_t *context)
590 struct thread *thread=arch_os_get_current_thread();
592 check_blockables_blocked_or_lose();
594 if (SymbolValue(INTERRUPT_PENDING,thread) != NIL)
595 lose("interrupt already pending\n");
596 /* If interrupts are disabled then INTERRUPT_PENDING is set and
597 * not PSEDUO_ATOMIC_INTERRUPTED. This is important for a pseudo
598 * atomic section inside a WITHOUT-INTERRUPTS.
600 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
601 store_signal_data_for_later(data,handler,signal,info,context);
602 SetSymbolValue(INTERRUPT_PENDING, T,thread);
603 FSHOW_SIGNAL((stderr,
604 "/maybe_defer_handler(%x,%d),thread=%lu: deferred\n",
605 (unsigned int)handler,signal,
606 (unsigned long)thread->os_thread));
609 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
610 * actually use its argument for anything on x86, so this branch
611 * may succeed even when context is null (gencgc alloc()) */
613 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
614 /* FIXME: this foreign_function_call_active test is dubious at
615 * best. If a foreign call is made in a pseudo atomic section
616 * (?) or more likely a pseudo atomic section is in a foreign
617 * call then an interrupt is executed immediately. Maybe it
618 * has to do with C code not maintaining pseudo atomic
619 * properly. MG - 2005-08-10 */
620 (!foreign_function_call_active) &&
622 arch_pseudo_atomic_atomic(context)) {
623 store_signal_data_for_later(data,handler,signal,info,context);
624 arch_set_pseudo_atomic_interrupted(context);
625 FSHOW_SIGNAL((stderr,
626 "/maybe_defer_handler(%x,%d),thread=%lu: deferred(PA)\n",
627 (unsigned int)handler,signal,
628 (unsigned long)thread->os_thread));
631 FSHOW_SIGNAL((stderr,
632 "/maybe_defer_handler(%x,%d),thread=%lu: not deferred\n",
633 (unsigned int)handler,signal,
634 (unsigned long)thread->os_thread));
639 store_signal_data_for_later (struct interrupt_data *data, void *handler,
641 siginfo_t *info, os_context_t *context)
643 if (data->pending_handler)
644 lose("tried to overwrite pending interrupt handler %x with %x\n",
645 data->pending_handler, handler);
647 lose("tried to defer null interrupt handler\n");
648 data->pending_handler = handler;
649 data->pending_signal = signal;
651 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
653 FSHOW_SIGNAL((stderr, "/store_signal_data_for_later: signal: %d\n", signal));
656 /* the signal mask in the context (from before we were
657 * interrupted) is copied to be restored when
658 * run_deferred_handler happens. Then the usually-blocked
659 * signals are added to the mask in the context so that we are
660 * running with blocked signals when the handler returns */
661 sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
662 sigaddset_deferrable(os_context_sigmask_addr(context));
667 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
669 os_context_t *context = arch_os_get_context(&void_context);
671 struct thread *thread;
672 struct interrupt_data *data;
674 thread=arch_os_get_current_thread();
675 data=thread->interrupt_data;
677 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
678 os_restore_fp_control(context);
681 if(maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
683 interrupt_handle_now(signal, info, context);
684 #ifdef LISP_FEATURE_DARWIN
685 /* Work around G5 bug */
686 DARWIN_FIX_CONTEXT(context);
691 low_level_interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
693 os_context_t *context = (os_context_t*)void_context;
695 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
696 os_restore_fp_control(context);
699 check_blockables_blocked_or_lose();
700 check_interrupts_enabled_or_lose(context);
701 interrupt_low_level_handlers[signal](signal, info, void_context);
702 #ifdef LISP_FEATURE_DARWIN
703 /* Work around G5 bug */
704 DARWIN_FIX_CONTEXT(context);
709 low_level_maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
711 os_context_t *context = arch_os_get_context(&void_context);
712 struct thread *thread;
713 struct interrupt_data *data;
715 thread=arch_os_get_current_thread();
716 data=thread->interrupt_data;
718 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
719 os_restore_fp_control(context);
722 if(maybe_defer_handler(low_level_interrupt_handle_now,data,
723 signal,info,context))
725 low_level_interrupt_handle_now(signal, info, context);
726 #ifdef LISP_FEATURE_DARWIN
727 /* Work around G5 bug */
728 DARWIN_FIX_CONTEXT(context);
733 #ifdef LISP_FEATURE_SB_THREAD
736 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
738 os_context_t *context = arch_os_get_context(&void_context);
740 struct thread *thread=arch_os_get_current_thread();
743 if ((arch_pseudo_atomic_atomic(context) ||
744 SymbolValue(GC_INHIBIT,thread) != NIL)) {
745 SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
746 if (SymbolValue(GC_INHIBIT,thread) == NIL)
747 arch_set_pseudo_atomic_interrupted(context);
748 FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred\n",
751 /* need the context stored so it can have registers scavenged */
752 fake_foreign_function_call(context);
754 sigfillset(&ss); /* Block everything. */
755 thread_sigmask(SIG_BLOCK,&ss,0);
757 if(thread->state!=STATE_RUNNING) {
758 lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
759 fixnum_value(thread->state));
761 thread->state=STATE_SUSPENDED;
762 FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
764 #if defined(SIG_RESUME_FROM_GC)
765 sigemptyset(&ss); sigaddset(&ss,SIG_RESUME_FROM_GC);
767 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
770 /* It is possible to get SIGCONT (and probably other
771 * non-blockable signals) here. */
772 #ifdef SIG_RESUME_FROM_GC
775 do { sigwait(&ss, &sigret); }
776 while (sigret != SIG_RESUME_FROM_GC);
779 while (sigwaitinfo(&ss,0) != SIG_STOP_FOR_GC);
782 FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
783 if(thread->state!=STATE_RUNNING) {
784 lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
785 fixnum_value(thread->state));
788 undo_fake_foreign_function_call(context);
794 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
796 os_context_t *context = arch_os_get_context(&void_context);
797 interrupt_handle_now(signal, info, context);
798 #ifdef LISP_FEATURE_DARWIN
799 DARWIN_FIX_CONTEXT(context);
804 * stuff to detect and handle hitting the GC trigger
807 #ifndef LISP_FEATURE_GENCGC
808 /* since GENCGC has its own way to record trigger */
810 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
812 if (current_auto_gc_trigger == NULL)
815 void *badaddr=arch_get_bad_addr(signal,info,context);
816 return (badaddr >= (void *)current_auto_gc_trigger &&
817 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
822 /* manipulate the signal context and stack such that when the handler
823 * returns, it will call function instead of whatever it was doing
827 #if (defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
828 extern int *context_eflags_addr(os_context_t *context);
831 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
832 extern void post_signal_tramp(void);
833 extern void call_into_lisp_tramp(void);
835 arrange_return_to_lisp_function(os_context_t *context, lispobj function)
837 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
838 void * fun=native_pointer(function);
839 void *code = &(((struct simple_fun *) fun)->code);
842 /* Build a stack frame showing `interrupted' so that the
843 * user's backtrace makes (as much) sense (as usual) */
845 /* FIXME: what about restoring fp state? */
846 /* FIXME: what about restoring errno? */
847 #ifdef LISP_FEATURE_X86
848 /* Suppose the existence of some function that saved all
849 * registers, called call_into_lisp, then restored GP registers and
850 * returned. It would look something like this:
858 pushl {address of function to call}
859 call 0x8058db0 <call_into_lisp>
866 * What we do here is set up the stack that call_into_lisp would
867 * expect to see if it had been called by this code, and frob the
868 * signal context so that signal return goes directly to call_into_lisp,
869 * and when that function (and the lisp function it invoked) returns,
870 * it returns to the second half of this imaginary function which
871 * restores all registers and returns to C
873 * For this to work, the latter part of the imaginary function
874 * must obviously exist in reality. That would be post_signal_tramp
877 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
879 #if defined(LISP_FEATURE_DARWIN)
880 u32 *register_save_area = (u32 *)os_validate(0, 0x40);
882 FSHOW_SIGNAL((stderr, "/arrange_return_to_lisp_function: preparing to go to function %x, sp: %x\n", function, sp));
883 FSHOW_SIGNAL((stderr, "/arrange_return_to_lisp_function: context: %x, &context %x\n", context, &context));
885 /* 1. os_validate (malloc/mmap) register_save_block
886 * 2. copy register state into register_save_block
887 * 3. put a pointer to register_save_block in a register in the context
888 * 4. set the context's EIP to point to a trampoline which:
889 * a. builds the fake stack frame from the block
891 * c. calls the function
894 *register_save_area = *os_context_pc_addr(context);
895 *(register_save_area + 1) = function;
896 *(register_save_area + 2) = *os_context_register_addr(context,reg_EDI);
897 *(register_save_area + 3) = *os_context_register_addr(context,reg_ESI);
898 *(register_save_area + 4) = *os_context_register_addr(context,reg_EDX);
899 *(register_save_area + 5) = *os_context_register_addr(context,reg_ECX);
900 *(register_save_area + 6) = *os_context_register_addr(context,reg_EBX);
901 *(register_save_area + 7) = *os_context_register_addr(context,reg_EAX);
902 *(register_save_area + 8) = *context_eflags_addr(context);
904 *os_context_pc_addr(context) = call_into_lisp_tramp;
905 *os_context_register_addr(context,reg_ECX) = register_save_area;
908 /* return address for call_into_lisp: */
909 *(sp-15) = (u32)post_signal_tramp;
910 *(sp-14) = function; /* args for call_into_lisp : function*/
911 *(sp-13) = 0; /* arg array */
912 *(sp-12) = 0; /* no. args */
913 /* this order matches that used in POPAD */
914 *(sp-11)=*os_context_register_addr(context,reg_EDI);
915 *(sp-10)=*os_context_register_addr(context,reg_ESI);
917 *(sp-9)=*os_context_register_addr(context,reg_ESP)-8;
918 /* POPAD ignores the value of ESP: */
920 *(sp-7)=*os_context_register_addr(context,reg_EBX);
922 *(sp-6)=*os_context_register_addr(context,reg_EDX);
923 *(sp-5)=*os_context_register_addr(context,reg_ECX);
924 *(sp-4)=*os_context_register_addr(context,reg_EAX);
925 *(sp-3)=*context_eflags_addr(context);
926 *(sp-2)=*os_context_register_addr(context,reg_EBP);
927 *(sp-1)=*os_context_pc_addr(context);
931 #elif defined(LISP_FEATURE_X86_64)
932 u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
933 /* return address for call_into_lisp: */
934 *(sp-18) = (u64)post_signal_tramp;
936 *(sp-17)=*os_context_register_addr(context,reg_R15);
937 *(sp-16)=*os_context_register_addr(context,reg_R14);
938 *(sp-15)=*os_context_register_addr(context,reg_R13);
939 *(sp-14)=*os_context_register_addr(context,reg_R12);
940 *(sp-13)=*os_context_register_addr(context,reg_R11);
941 *(sp-12)=*os_context_register_addr(context,reg_R10);
942 *(sp-11)=*os_context_register_addr(context,reg_R9);
943 *(sp-10)=*os_context_register_addr(context,reg_R8);
944 *(sp-9)=*os_context_register_addr(context,reg_RDI);
945 *(sp-8)=*os_context_register_addr(context,reg_RSI);
946 /* skip RBP and RSP */
947 *(sp-7)=*os_context_register_addr(context,reg_RBX);
948 *(sp-6)=*os_context_register_addr(context,reg_RDX);
949 *(sp-5)=*os_context_register_addr(context,reg_RCX);
950 *(sp-4)=*os_context_register_addr(context,reg_RAX);
951 *(sp-3)=*context_eflags_addr(context);
952 *(sp-2)=*os_context_register_addr(context,reg_RBP);
953 *(sp-1)=*os_context_pc_addr(context);
955 *os_context_register_addr(context,reg_RDI) =
956 (os_context_register_t)function; /* function */
957 *os_context_register_addr(context,reg_RSI) = 0; /* arg. array */
958 *os_context_register_addr(context,reg_RDX) = 0; /* no. args */
960 struct thread *th=arch_os_get_current_thread();
961 build_fake_control_stack_frames(th,context);
964 #ifdef LISP_FEATURE_X86
966 #if !defined(LISP_FEATURE_DARWIN)
967 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
968 *os_context_register_addr(context,reg_ECX) = 0;
969 *os_context_register_addr(context,reg_EBP) = (os_context_register_t)(sp-2);
971 *os_context_register_addr(context,reg_UESP) =
972 (os_context_register_t)(sp-15);
974 *os_context_register_addr(context,reg_ESP) = (os_context_register_t)(sp-15);
975 #endif /* __NETBSD__ */
976 #endif /* LISP_FEATURE_DARWIN */
978 #elif defined(LISP_FEATURE_X86_64)
979 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
980 *os_context_register_addr(context,reg_RCX) = 0;
981 *os_context_register_addr(context,reg_RBP) = (os_context_register_t)(sp-2);
982 *os_context_register_addr(context,reg_RSP) = (os_context_register_t)(sp-18);
984 /* this much of the calling convention is common to all
986 *os_context_pc_addr(context) = (os_context_register_t)(unsigned long)code;
987 *os_context_register_addr(context,reg_NARGS) = 0;
988 *os_context_register_addr(context,reg_LIP) =
989 (os_context_register_t)(unsigned long)code;
990 *os_context_register_addr(context,reg_CFP) =
991 (os_context_register_t)(unsigned long)current_control_frame_pointer;
993 #ifdef ARCH_HAS_NPC_REGISTER
994 *os_context_npc_addr(context) =
995 4 + *os_context_pc_addr(context);
997 #ifdef LISP_FEATURE_SPARC
998 *os_context_register_addr(context,reg_CODE) =
999 (os_context_register_t)(fun + FUN_POINTER_LOWTAG);
1003 #ifdef LISP_FEATURE_SB_THREAD
1005 /* FIXME: this function can go away when all lisp handlers are invoked
1006 * via arrange_return_to_lisp_function. */
1008 interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
1010 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
1012 /* let the handler enable interrupts again when it sees fit */
1013 sigaddset_deferrable(os_context_sigmask_addr(context));
1014 arrange_return_to_lisp_function(context, SymbolFunction(RUN_INTERRUPTION));
1019 /* KLUDGE: Theoretically the approach we use for undefined alien
1020 * variables should work for functions as well, but on PPC/Darwin
1021 * we get bus error at bogus addresses instead, hence this workaround,
1022 * that has the added benefit of automatically discriminating between
1023 * functions and variables.
1026 undefined_alien_function() {
1027 funcall0(SymbolFunction(UNDEFINED_ALIEN_FUNCTION_ERROR));
1031 handle_guard_page_triggered(os_context_t *context,os_vm_address_t addr)
1033 struct thread *th=arch_os_get_current_thread();
1035 /* note the os_context hackery here. When the signal handler returns,
1036 * it won't go back to what it was doing ... */
1037 if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
1038 addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
1039 /* We hit the end of the control stack: disable guard page
1040 * protection so the error handler has some headroom, protect the
1041 * previous page so that we can catch returns from the guard page
1042 * and restore it. */
1043 protect_control_stack_guard_page(0);
1044 protect_control_stack_return_guard_page(1);
1046 arrange_return_to_lisp_function
1047 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
1050 else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
1051 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
1052 /* We're returning from the guard page: reprotect it, and
1053 * unprotect this one. This works even if we somehow missed
1054 * the return-guard-page, and hit it on our way to new
1055 * exhaustion instead. */
1056 protect_control_stack_guard_page(1);
1057 protect_control_stack_return_guard_page(0);
1060 else if (addr >= undefined_alien_address &&
1061 addr < undefined_alien_address + os_vm_page_size) {
1062 arrange_return_to_lisp_function
1063 (context, SymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
1069 #ifndef LISP_FEATURE_GENCGC
1070 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
1071 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
1072 * whether the signal was due to treading on the mprotect()ed zone -
1073 * and if so, arrange for a GC to happen. */
1074 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
1077 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
1079 os_context_t *context=(os_context_t *) void_context;
1081 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
1082 struct thread *thread=arch_os_get_current_thread();
1083 clear_auto_gc_trigger();
1084 /* Don't flood the system with interrupts if the need to gc is
1085 * already noted. This can happen for example when SUB-GC
1086 * allocates or after a gc triggered in a WITHOUT-GCING. */
1087 if (SymbolValue(GC_PENDING,thread) == NIL) {
1088 if (SymbolValue(GC_INHIBIT,thread) == NIL) {
1089 if (arch_pseudo_atomic_atomic(context)) {
1090 /* set things up so that GC happens when we finish
1092 SetSymbolValue(GC_PENDING,T,thread);
1093 arch_set_pseudo_atomic_interrupted(context);
1095 interrupt_maybe_gc_int(signal,info,void_context);
1098 SetSymbolValue(GC_PENDING,T,thread);
1108 /* this is also used by gencgc, in alloc() */
1110 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
1112 os_context_t *context=(os_context_t *) void_context;
1113 #ifndef LISP_FEATURE_WIN32
1114 struct thread *thread=arch_os_get_current_thread();
1117 fake_foreign_function_call(context);
1119 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
1120 * which case we will be running with no gc trigger barrier
1121 * thing for a while. But it shouldn't be long until the end
1124 * FIXME: It would be good to protect the end of dynamic space
1125 * and signal a storage condition from there.
1128 /* Restore the signal mask from the interrupted context before
1129 * calling into Lisp if interrupts are enabled. Why not always?
1131 * Suppose there is a WITHOUT-INTERRUPTS block far, far out. If an
1132 * interrupt hits while in SUB-GC, it is deferred and the
1133 * os_context_sigmask of that interrupt is set to block further
1134 * deferrable interrupts (until the first one is
1135 * handled). Unfortunately, that context refers to this place and
1136 * when we return from here the signals will not be blocked.
1138 * A kludgy alternative is to propagate the sigmask change to the
1141 #ifndef LISP_FEATURE_WIN32
1142 if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL)
1143 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
1144 #ifdef LISP_FEATURE_SB_THREAD
1148 #if defined(SIG_RESUME_FROM_GC)
1149 sigaddset(&new,SIG_RESUME_FROM_GC);
1151 sigaddset(&new,SIG_STOP_FOR_GC);
1152 thread_sigmask(SIG_UNBLOCK,&new,0);
1156 funcall0(SymbolFunction(SUB_GC));
1158 undo_fake_foreign_function_call(context);
1164 * noise to install handlers
1167 #ifndef LISP_FEATURE_WIN32
1168 /* In Linux 2.4 synchronous signals (sigtrap & co) can be delivered if
1169 * they are blocked, in Linux 2.6 the default handler is invoked
1170 * instead that usually coredumps. One might hastily think that adding
1171 * SA_NODEFER helps, but until ~2.6.13 if SA_NODEFER is specified then
1172 * the whole sa_mask is ignored and instead of not adding the signal
1173 * in question to the mask. That means if it's not blockable the
1174 * signal must be unblocked at the beginning of signal handlers.
1176 * It turns out that NetBSD's SA_NODEFER doesn't DTRT in a different
1177 * way: if SA_NODEFER is set and the signal is in sa_mask, the signal
1178 * will be unblocked in the sigmask during the signal handler. -- RMK
1181 static volatile int sigaction_nodefer_works = -1;
1183 #define SA_NODEFER_TEST_BLOCK_SIGNAL SIGABRT
1184 #define SA_NODEFER_TEST_KILL_SIGNAL SIGUSR1
1187 sigaction_nodefer_test_handler(int signal, siginfo_t *info, void *void_context)
1189 sigset_t empty, current;
1191 sigemptyset(&empty);
1192 sigprocmask(SIG_BLOCK, &empty, ¤t);
1193 /* There should be exactly two blocked signals: the two we added
1194 * to sa_mask when setting up the handler. NetBSD doesn't block
1195 * the signal we're handling when SA_NODEFER is set; Linux before
1196 * 2.6.13 or so also doesn't block the other signal when
1197 * SA_NODEFER is set. */
1198 for(i = 1; i < NSIG; i++)
1199 if (sigismember(¤t, i) !=
1200 (((i == SA_NODEFER_TEST_BLOCK_SIGNAL) || (i == signal)) ? 1 : 0)) {
1201 FSHOW_SIGNAL((stderr, "SA_NODEFER doesn't work, signal %d\n", i));
1202 sigaction_nodefer_works = 0;
1204 if (sigaction_nodefer_works == -1)
1205 sigaction_nodefer_works = 1;
1209 see_if_sigaction_nodefer_works()
1211 struct sigaction sa, old_sa;
1213 sa.sa_flags = SA_SIGINFO | SA_NODEFER;
1214 sa.sa_sigaction = sigaction_nodefer_test_handler;
1215 sigemptyset(&sa.sa_mask);
1216 sigaddset(&sa.sa_mask, SA_NODEFER_TEST_BLOCK_SIGNAL);
1217 sigaddset(&sa.sa_mask, SA_NODEFER_TEST_KILL_SIGNAL);
1218 sigaction(SA_NODEFER_TEST_KILL_SIGNAL, &sa, &old_sa);
1219 /* Make sure no signals are blocked. */
1222 sigemptyset(&empty);
1223 sigprocmask(SIG_SETMASK, &empty, 0);
1225 kill(getpid(), SA_NODEFER_TEST_KILL_SIGNAL);
1226 while (sigaction_nodefer_works == -1);
1227 sigaction(SA_NODEFER_TEST_KILL_SIGNAL, &old_sa, NULL);
1230 #undef SA_NODEFER_TEST_BLOCK_SIGNAL
1231 #undef SA_NODEFER_TEST_KILL_SIGNAL
1234 unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1238 sigemptyset(&unblock);
1239 sigaddset(&unblock, signal);
1240 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1241 interrupt_handle_now_handler(signal, info, void_context);
1245 low_level_unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1249 sigemptyset(&unblock);
1250 sigaddset(&unblock, signal);
1251 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1252 (*interrupt_low_level_handlers[signal])(signal, info, void_context);
1256 undoably_install_low_level_interrupt_handler (int signal,
1261 struct sigaction sa;
1263 if (0 > signal || signal >= NSIG) {
1264 lose("bad signal number %d\n", signal);
1267 if (ARE_SAME_HANDLER(handler, SIG_DFL))
1268 sa.sa_sigaction = handler;
1269 else if (sigismember(&deferrable_sigset,signal))
1270 sa.sa_sigaction = low_level_maybe_now_maybe_later;
1271 /* The use of a trampoline appears to break the
1272 arch_os_get_context() workaround for SPARC/Linux. For now,
1273 don't use the trampoline (and so be vulnerable to the problems
1274 that SA_NODEFER is meant to solve. */
1275 #if !(defined(LISP_FEATURE_SPARC) && defined(LISP_FEATURE_LINUX))
1276 else if (!sigaction_nodefer_works &&
1277 !sigismember(&blockable_sigset, signal))
1278 sa.sa_sigaction = low_level_unblock_me_trampoline;
1281 sa.sa_sigaction = handler;
1283 sigcopyset(&sa.sa_mask, &blockable_sigset);
1284 sa.sa_flags = SA_SIGINFO | SA_RESTART
1285 | (sigaction_nodefer_works ? SA_NODEFER : 0);
1286 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
1287 if((signal==SIG_MEMORY_FAULT)
1288 #ifdef SIG_MEMORY_FAULT2
1289 || (signal==SIG_MEMORY_FAULT2)
1291 #ifdef SIG_INTERRUPT_THREAD
1292 || (signal==SIG_INTERRUPT_THREAD)
1295 sa.sa_flags |= SA_ONSTACK;
1298 sigaction(signal, &sa, NULL);
1299 interrupt_low_level_handlers[signal] =
1300 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
1304 /* This is called from Lisp. */
1306 install_handler(int signal, void handler(int, siginfo_t*, void*))
1308 #ifndef LISP_FEATURE_WIN32
1309 struct sigaction sa;
1311 union interrupt_handler oldhandler;
1313 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
1316 sigaddset(&new, signal);
1317 thread_sigmask(SIG_BLOCK, &new, &old);
1319 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%x\n",
1320 (unsigned int)interrupt_low_level_handlers[signal]));
1321 if (interrupt_low_level_handlers[signal]==0) {
1322 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
1323 ARE_SAME_HANDLER(handler, SIG_IGN))
1324 sa.sa_sigaction = handler;
1325 else if (sigismember(&deferrable_sigset, signal))
1326 sa.sa_sigaction = maybe_now_maybe_later;
1327 else if (!sigaction_nodefer_works &&
1328 !sigismember(&blockable_sigset, signal))
1329 sa.sa_sigaction = unblock_me_trampoline;
1331 sa.sa_sigaction = interrupt_handle_now_handler;
1333 sigcopyset(&sa.sa_mask, &blockable_sigset);
1334 sa.sa_flags = SA_SIGINFO | SA_RESTART |
1335 (sigaction_nodefer_works ? SA_NODEFER : 0);
1336 sigaction(signal, &sa, NULL);
1339 oldhandler = interrupt_handlers[signal];
1340 interrupt_handlers[signal].c = handler;
1342 thread_sigmask(SIG_SETMASK, &old, 0);
1344 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
1346 return (unsigned long)oldhandler.lisp;
1348 /* Probably-wrong Win32 hack */
1356 #ifndef LISP_FEATURE_WIN32
1358 SHOW("entering interrupt_init()");
1359 see_if_sigaction_nodefer_works();
1360 sigemptyset(&deferrable_sigset);
1361 sigemptyset(&blockable_sigset);
1362 sigaddset_deferrable(&deferrable_sigset);
1363 sigaddset_blockable(&blockable_sigset);
1365 /* Set up high level handler information. */
1366 for (i = 0; i < NSIG; i++) {
1367 interrupt_handlers[i].c =
1368 /* (The cast here blasts away the distinction between
1369 * SA_SIGACTION-style three-argument handlers and
1370 * signal(..)-style one-argument handlers, which is OK
1371 * because it works to call the 1-argument form where the
1372 * 3-argument form is expected.) */
1373 (void (*)(int, siginfo_t*, void*))SIG_DFL;
1376 SHOW("returning from interrupt_init()");