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"
67 #include "genesis/fdefn.h"
68 #include "genesis/simple-fun.h"
69 #include "genesis/cons.h"
73 static void run_deferred_handler(struct interrupt_data *data, void *v_context);
74 #ifndef LISP_FEATURE_WIN32
75 static void store_signal_data_for_later (struct interrupt_data *data,
76 void *handler, int signal,
78 os_context_t *context);
79 boolean interrupt_maybe_gc_int(int signal, siginfo_t *info, void *v_context);
82 sigaddset_deferrable(sigset_t *s)
86 sigaddset(s, SIGQUIT);
87 sigaddset(s, SIGPIPE);
88 sigaddset(s, SIGALRM);
90 sigaddset(s, SIGTSTP);
91 sigaddset(s, SIGCHLD);
93 sigaddset(s, SIGXCPU);
94 sigaddset(s, SIGXFSZ);
95 sigaddset(s, SIGVTALRM);
96 sigaddset(s, SIGPROF);
97 sigaddset(s, SIGWINCH);
98 sigaddset(s, SIGUSR1);
99 sigaddset(s, SIGUSR2);
100 #ifdef LISP_FEATURE_SB_THREAD
101 sigaddset(s, SIG_INTERRUPT_THREAD);
106 sigaddset_blockable(sigset_t *s)
108 sigaddset_deferrable(s);
109 #ifdef LISP_FEATURE_SB_THREAD
110 sigaddset(s, SIG_STOP_FOR_GC);
114 /* initialized in interrupt_init */
115 static sigset_t deferrable_sigset;
116 static sigset_t blockable_sigset;
120 check_blockables_blocked_or_lose()
122 #ifndef LISP_FEATURE_WIN32
123 /* Get the current sigmask, by blocking the empty set. */
124 sigset_t empty,current;
127 thread_sigmask(SIG_BLOCK, &empty, ¤t);
128 for(i = 1; i < NSIG; i++) {
129 if (sigismember(&blockable_sigset, i) && !sigismember(¤t, i))
130 lose("blockable signal %d not blocked\n",i);
136 check_interrupts_enabled_or_lose(os_context_t *context)
138 struct thread *thread=arch_os_get_current_thread();
139 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL)
140 lose("interrupts not enabled\n");
142 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
143 (!foreign_function_call_active) &&
145 arch_pseudo_atomic_atomic(context))
146 lose ("in pseudo atomic section\n");
149 /* When we catch an internal error, should we pass it back to Lisp to
150 * be handled in a high-level way? (Early in cold init, the answer is
151 * 'no', because Lisp is still too brain-dead to handle anything.
152 * After sufficient initialization has been completed, the answer
154 boolean internal_errors_enabled = 0;
156 #ifndef LISP_FEATURE_WIN32
157 static void (*interrupt_low_level_handlers[NSIG]) (int, siginfo_t*, void*);
159 union interrupt_handler interrupt_handlers[NSIG];
161 /* At the toplevel repl we routinely call this function. The signal
162 * mask ought to be clear anyway most of the time, but may be non-zero
163 * if we were interrupted e.g. while waiting for a queue. */
166 reset_signal_mask(void)
168 #ifndef LISP_FEATURE_WIN32
171 thread_sigmask(SIG_SETMASK,&new,0);
176 block_blockable_signals(void)
178 #ifndef LISP_FEATURE_WIN32
179 thread_sigmask(SIG_BLOCK, &blockable_sigset, 0);
185 * utility routines used by various signal handlers
189 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
191 #ifndef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
195 /* Build a fake stack frame or frames */
197 current_control_frame_pointer =
198 (lispobj *)(unsigned long)
199 (*os_context_register_addr(context, reg_CSP));
200 if ((lispobj *)(unsigned long)
201 (*os_context_register_addr(context, reg_CFP))
202 == current_control_frame_pointer) {
203 /* There is a small window during call where the callee's
204 * frame isn't built yet. */
205 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
206 == FUN_POINTER_LOWTAG) {
207 /* We have called, but not built the new frame, so
208 * build it for them. */
209 current_control_frame_pointer[0] =
210 *os_context_register_addr(context, reg_OCFP);
211 current_control_frame_pointer[1] =
212 *os_context_register_addr(context, reg_LRA);
213 current_control_frame_pointer += 8;
214 /* Build our frame on top of it. */
215 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
218 /* We haven't yet called, build our frame as if the
219 * partial frame wasn't there. */
220 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
223 /* We can't tell whether we are still in the caller if it had to
224 * allocate a stack frame due to stack arguments. */
225 /* This observation provoked some past CMUCL maintainer to ask
226 * "Can anything strange happen during return?" */
229 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
232 current_control_stack_pointer = current_control_frame_pointer + 8;
234 current_control_frame_pointer[0] = oldcont;
235 current_control_frame_pointer[1] = NIL;
236 current_control_frame_pointer[2] =
237 (lispobj)(*os_context_register_addr(context, reg_CODE));
241 /* Stores the context for gc to scavange and builds fake stack
244 fake_foreign_function_call(os_context_t *context)
247 struct thread *thread=arch_os_get_current_thread();
249 /* context_index incrementing must not be interrupted */
250 check_blockables_blocked_or_lose();
252 /* Get current Lisp state from context. */
254 dynamic_space_free_pointer =
255 (lispobj *)(unsigned long)
256 (*os_context_register_addr(context, reg_ALLOC));
257 /* fprintf(stderr,"dynamic_space_free_pointer: %p\n", dynamic_space_free_pointer); */
258 #if defined(LISP_FEATURE_ALPHA)
259 if ((long)dynamic_space_free_pointer & 1) {
260 lose("dead in fake_foreign_function_call, context = %x\n", context);
265 current_binding_stack_pointer =
266 (lispobj *)(unsigned long)
267 (*os_context_register_addr(context, reg_BSP));
270 build_fake_control_stack_frames(thread,context);
272 /* Do dynamic binding of the active interrupt context index
273 * and save the context in the context array. */
275 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
277 if (context_index >= MAX_INTERRUPTS) {
278 lose("maximum interrupt nesting depth (%d) exceeded\n", MAX_INTERRUPTS);
281 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
282 make_fixnum(context_index + 1),thread);
284 thread->interrupt_contexts[context_index] = context;
286 /* no longer in Lisp now */
287 foreign_function_call_active = 1;
290 /* blocks all blockable signals. If you are calling from a signal handler,
291 * the usual signal mask will be restored from the context when the handler
292 * finishes. Otherwise, be careful */
294 undo_fake_foreign_function_call(os_context_t *context)
296 struct thread *thread=arch_os_get_current_thread();
297 /* Block all blockable signals. */
298 block_blockable_signals();
300 /* going back into Lisp */
301 foreign_function_call_active = 0;
303 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
307 /* Put the dynamic space free pointer back into the context. */
308 *os_context_register_addr(context, reg_ALLOC) =
309 (unsigned long) dynamic_space_free_pointer
310 | (*os_context_register_addr(context, reg_ALLOC)
313 ((unsigned long)(*os_context_register_addr(context, reg_ALLOC)) & ~LOWTAG_MASK)
314 | ((unsigned long) dynamic_space_free_pointer & LOWTAG_MASK);
319 /* a handler for the signal caused by execution of a trap opcode
320 * signalling an internal error */
322 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
327 fake_foreign_function_call(context);
329 if (!internal_errors_enabled) {
330 describe_internal_error(context);
331 /* There's no good way to recover from an internal error
332 * before the Lisp error handling mechanism is set up. */
333 lose("internal error too early in init, can't recover\n");
336 /* Allocate the SAP object while the interrupts are still
338 context_sap = alloc_sap(context);
340 #ifndef LISP_FEATURE_WIN32
341 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
344 SHOW("in interrupt_internal_error");
346 /* Display some rudimentary debugging information about the
347 * error, so that even if the Lisp error handler gets badly
348 * confused, we have a chance to determine what's going on. */
349 describe_internal_error(context);
351 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
352 continuable ? T : NIL);
354 undo_fake_foreign_function_call(context); /* blocks signals again */
356 arch_skip_instruction(context);
360 interrupt_handle_pending(os_context_t *context)
362 struct thread *thread;
363 struct interrupt_data *data;
365 check_blockables_blocked_or_lose();
367 thread=arch_os_get_current_thread();
368 data=thread->interrupt_data;
370 /* If pseudo_atomic_interrupted is set then the interrupt is going
371 * to be handled now, ergo it's safe to clear it. */
373 /* CLH: 20060220 FIXME This sould probably be arch_clear_p_a_i but
374 * the behavior of arch_clear_p_a_i and clear_p_a_i are slightly
375 * different on PPC. */
376 arch_clear_pseudo_atomic_interrupted(context);
378 if (SymbolValue(GC_INHIBIT,thread)==NIL) {
379 #ifdef LISP_FEATURE_SB_THREAD
380 if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
381 /* another thread has already initiated a gc, this attempt
382 * might as well be cancelled */
383 SetSymbolValue(GC_PENDING,NIL,thread);
384 SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
385 sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
388 if (SymbolValue(GC_PENDING,thread) != NIL) {
389 /* GC_PENDING is cleared in SUB-GC, or if another thread
390 * is doing a gc already we will get a SIG_STOP_FOR_GC and
391 * that will clear it. */
392 interrupt_maybe_gc_int(0,NULL,context);
394 check_blockables_blocked_or_lose();
397 /* we may be here only to do the gc stuff, if interrupts are
398 * enabled run the pending handler */
399 if (!((SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) ||
401 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
402 (!foreign_function_call_active) &&
404 arch_pseudo_atomic_atomic(context)))) {
406 /* There may be no pending handler, because it was only a gc
407 * that had to be executed or because pseudo atomic triggered
408 * twice for a single interrupt. For the interested reader,
409 * that may happen if an interrupt hits after the interrupted
410 * flag is cleared but before pseduo-atomic is set and a
411 * pseudo atomic is interrupted in that interrupt. */
412 if (data->pending_handler) {
414 /* If we're here as the result of a pseudo-atomic as opposed
415 * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
416 * NIL, because maybe_defer_handler sets
417 * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
418 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
420 #ifndef LISP_FEATURE_WIN32
421 /* restore the saved signal mask from the original signal (the
422 * one that interrupted us during the critical section) into the
423 * os_context for the signal we're currently in the handler for.
424 * This should ensure that when we return from the handler the
425 * blocked signals are unblocked */
426 sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
428 sigemptyset(&data->pending_mask);
430 /* This will break on sparc linux: the deferred handler really wants
431 * to be called with a void_context */
432 run_deferred_handler(data,(void *)context);
438 * the two main signal handlers:
439 * interrupt_handle_now(..)
440 * maybe_now_maybe_later(..)
442 * to which we have added interrupt_handle_now_handler(..). Why?
443 * Well, mostly because the SPARC/Linux platform doesn't quite do
444 * signals the way we want them done. The third argument in the
445 * handler isn't filled in by the kernel properly, so we fix it up
446 * ourselves in the arch_os_get_context(..) function; however, we only
447 * want to do this when we first hit the handler, and not when
448 * interrupt_handle_now(..) is being called from some other handler
449 * (when the fixup will already have been done). -- CSR, 2002-07-23
453 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
455 os_context_t *context = (os_context_t*)void_context;
456 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
457 boolean were_in_lisp;
459 union interrupt_handler handler;
460 check_blockables_blocked_or_lose();
461 #ifndef LISP_FEATURE_WIN32
462 if (sigismember(&deferrable_sigset,signal))
463 check_interrupts_enabled_or_lose(context);
466 #ifdef LISP_FEATURE_LINUX
467 /* Under Linux on some architectures, we appear to have to restore
468 the FPU control word from the context, as after the signal is
469 delivered we appear to have a null FPU control word. */
470 os_restore_fp_control(context);
472 handler = interrupt_handlers[signal];
474 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
478 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
479 were_in_lisp = !foreign_function_call_active;
483 fake_foreign_function_call(context);
486 FSHOW_SIGNAL((stderr,
487 "/entering interrupt_handle_now(%d, info, context)\n",
490 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
492 /* This can happen if someone tries to ignore or default one
493 * of the signals we need for runtime support, and the runtime
494 * support decides to pass on it. */
495 lose("no handler for signal %d in interrupt_handle_now(..)\n", signal);
497 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
498 /* Once we've decided what to do about contexts in a
499 * return-elsewhere world (the original context will no longer
500 * be available; should we copy it or was nobody using it anyway?)
501 * then we should convert this to return-elsewhere */
503 /* CMUCL comment said "Allocate the SAPs while the interrupts
504 * are still disabled.". I (dan, 2003.08.21) assume this is
505 * because we're not in pseudoatomic and allocation shouldn't
506 * be interrupted. In which case it's no longer an issue as
507 * all our allocation from C now goes through a PA wrapper,
508 * but still, doesn't hurt.
510 * Yeah, but non-gencgc platforms don't really wrap allocation
511 * in PA. MG - 2005-08-29 */
513 lispobj info_sap,context_sap = alloc_sap(context);
514 info_sap = alloc_sap(info);
515 /* Leave deferrable signals blocked, the handler itself will
516 * allow signals again when it sees fit. */
517 #ifdef LISP_FEATURE_SB_THREAD
520 sigemptyset(&unblock);
521 sigaddset(&unblock, SIG_STOP_FOR_GC);
522 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
526 FSHOW_SIGNAL((stderr,"/calling Lisp-level handler\n"));
528 funcall3(handler.lisp,
534 FSHOW_SIGNAL((stderr,"/calling C-level handler\n"));
536 #ifndef LISP_FEATURE_WIN32
537 /* Allow signals again. */
538 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
541 (*handler.c)(signal, info, void_context);
544 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
548 undo_fake_foreign_function_call(context); /* block signals again */
551 FSHOW_SIGNAL((stderr,
552 "/returning from interrupt_handle_now(%d, info, context)\n",
556 /* This is called at the end of a critical section if the indications
557 * are that some signal was deferred during the section. Note that as
558 * far as C or the kernel is concerned we dealt with the signal
559 * already; we're just doing the Lisp-level processing now that we
562 run_deferred_handler(struct interrupt_data *data, void *v_context) {
563 /* The pending_handler may enable interrupts and then another
564 * interrupt may hit, overwrite interrupt_data, so reset the
565 * pending handler before calling it. Trust the handler to finish
566 * with the siginfo before enabling interrupts. */
567 void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
568 data->pending_handler=0;
569 (*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
572 #ifndef LISP_FEATURE_WIN32
574 maybe_defer_handler(void *handler, struct interrupt_data *data,
575 int signal, siginfo_t *info, os_context_t *context)
577 struct thread *thread=arch_os_get_current_thread();
579 check_blockables_blocked_or_lose();
581 if (SymbolValue(INTERRUPT_PENDING,thread) != NIL)
582 lose("interrupt already pending\n");
583 /* If interrupts are disabled then INTERRUPT_PENDING is set and
584 * not PSEDUO_ATOMIC_INTERRUPTED. This is important for a pseudo
585 * atomic section inside a WITHOUT-INTERRUPTS.
587 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
588 store_signal_data_for_later(data,handler,signal,info,context);
589 SetSymbolValue(INTERRUPT_PENDING, T,thread);
590 FSHOW_SIGNAL((stderr,
591 "/maybe_defer_handler(%x,%d),thread=%lu: deferred\n",
592 (unsigned int)handler,signal,
593 (unsigned long)thread->os_thread));
596 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
597 * actually use its argument for anything on x86, so this branch
598 * may succeed even when context is null (gencgc alloc()) */
600 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
601 /* FIXME: this foreign_function_call_active test is dubious at
602 * best. If a foreign call is made in a pseudo atomic section
603 * (?) or more likely a pseudo atomic section is in a foreign
604 * call then an interrupt is executed immediately. Maybe it
605 * has to do with C code not maintaining pseudo atomic
606 * properly. MG - 2005-08-10 */
607 (!foreign_function_call_active) &&
609 arch_pseudo_atomic_atomic(context)) {
610 store_signal_data_for_later(data,handler,signal,info,context);
611 arch_set_pseudo_atomic_interrupted(context);
612 FSHOW_SIGNAL((stderr,
613 "/maybe_defer_handler(%x,%d),thread=%lu: deferred(PA)\n",
614 (unsigned int)handler,signal,
615 (unsigned long)thread->os_thread));
618 FSHOW_SIGNAL((stderr,
619 "/maybe_defer_handler(%x,%d),thread=%lu: not deferred\n",
620 (unsigned int)handler,signal,
621 (unsigned long)thread->os_thread));
626 store_signal_data_for_later (struct interrupt_data *data, void *handler,
628 siginfo_t *info, os_context_t *context)
630 if (data->pending_handler)
631 lose("tried to overwrite pending interrupt handler %x with %x\n",
632 data->pending_handler, handler);
634 lose("tried to defer null interrupt handler\n");
635 data->pending_handler = handler;
636 data->pending_signal = signal;
638 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
640 /* the signal mask in the context (from before we were
641 * interrupted) is copied to be restored when
642 * run_deferred_handler happens. Then the usually-blocked
643 * signals are added to the mask in the context so that we are
644 * running with blocked signals when the handler returns */
645 sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
646 sigaddset_deferrable(os_context_sigmask_addr(context));
651 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
653 os_context_t *context = arch_os_get_context(&void_context);
654 struct thread *thread=arch_os_get_current_thread();
655 struct interrupt_data *data=thread->interrupt_data;
656 #ifdef LISP_FEATURE_LINUX
657 os_restore_fp_control(context);
659 if(maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
661 interrupt_handle_now(signal, info, context);
662 #ifdef LISP_FEATURE_DARWIN
663 /* Work around G5 bug */
664 DARWIN_FIX_CONTEXT(context);
669 low_level_interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
671 os_context_t *context = (os_context_t*)void_context;
673 #ifdef LISP_FEATURE_LINUX
674 os_restore_fp_control(context);
676 check_blockables_blocked_or_lose();
677 check_interrupts_enabled_or_lose(context);
678 interrupt_low_level_handlers[signal](signal, info, void_context);
679 #ifdef LISP_FEATURE_DARWIN
680 /* Work around G5 bug */
681 DARWIN_FIX_CONTEXT(context);
686 low_level_maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
688 os_context_t *context = arch_os_get_context(&void_context);
689 struct thread *thread=arch_os_get_current_thread();
690 struct interrupt_data *data=thread->interrupt_data;
691 #ifdef LISP_FEATURE_LINUX
692 os_restore_fp_control(context);
694 if(maybe_defer_handler(low_level_interrupt_handle_now,data,
695 signal,info,context))
697 low_level_interrupt_handle_now(signal, info, context);
698 #ifdef LISP_FEATURE_DARWIN
699 /* Work around G5 bug */
700 DARWIN_FIX_CONTEXT(context);
705 #ifdef LISP_FEATURE_SB_THREAD
708 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
710 os_context_t *context = arch_os_get_context(&void_context);
711 struct thread *thread=arch_os_get_current_thread();
714 if ((arch_pseudo_atomic_atomic(context) ||
715 SymbolValue(GC_INHIBIT,thread) != NIL)) {
716 SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
717 if (SymbolValue(GC_INHIBIT,thread) == NIL)
718 arch_set_pseudo_atomic_interrupted(context);
719 FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred\n",
722 /* need the context stored so it can have registers scavenged */
723 fake_foreign_function_call(context);
725 sigfillset(&ss); /* Block everything. */
726 thread_sigmask(SIG_BLOCK,&ss,0);
728 if(thread->state!=STATE_RUNNING) {
729 lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
730 fixnum_value(thread->state));
732 thread->state=STATE_SUSPENDED;
733 FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
735 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
736 /* It is possible to get SIGCONT (and probably other
737 * non-blockable signals) here. */
738 while (sigwaitinfo(&ss,0) != SIG_STOP_FOR_GC);
739 FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
740 if(thread->state!=STATE_RUNNING) {
741 lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
742 fixnum_value(thread->state));
745 undo_fake_foreign_function_call(context);
751 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
753 os_context_t *context = arch_os_get_context(&void_context);
754 interrupt_handle_now(signal, info, context);
755 #ifdef LISP_FEATURE_DARWIN
756 DARWIN_FIX_CONTEXT(context);
761 * stuff to detect and handle hitting the GC trigger
764 #ifndef LISP_FEATURE_GENCGC
765 /* since GENCGC has its own way to record trigger */
767 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
769 if (current_auto_gc_trigger == NULL)
772 void *badaddr=arch_get_bad_addr(signal,info,context);
773 return (badaddr >= (void *)current_auto_gc_trigger &&
774 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
779 /* manipulate the signal context and stack such that when the handler
780 * returns, it will call function instead of whatever it was doing
784 #if (defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
785 extern int *context_eflags_addr(os_context_t *context);
788 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
789 extern void post_signal_tramp(void);
791 arrange_return_to_lisp_function(os_context_t *context, lispobj function)
793 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
794 void * fun=native_pointer(function);
795 void *code = &(((struct simple_fun *) fun)->code);
798 /* Build a stack frame showing `interrupted' so that the
799 * user's backtrace makes (as much) sense (as usual) */
801 /* FIXME: what about restoring fp state? */
802 /* FIXME: what about restoring errno? */
803 #ifdef LISP_FEATURE_X86
804 /* Suppose the existence of some function that saved all
805 * registers, called call_into_lisp, then restored GP registers and
806 * returned. It would look something like this:
814 pushl {address of function to call}
815 call 0x8058db0 <call_into_lisp>
822 * What we do here is set up the stack that call_into_lisp would
823 * expect to see if it had been called by this code, and frob the
824 * signal context so that signal return goes directly to call_into_lisp,
825 * and when that function (and the lisp function it invoked) returns,
826 * it returns to the second half of this imaginary function which
827 * restores all registers and returns to C
829 * For this to work, the latter part of the imaginary function
830 * must obviously exist in reality. That would be post_signal_tramp
833 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
835 /* return address for call_into_lisp: */
836 *(sp-15) = (u32)post_signal_tramp;
837 *(sp-14) = function; /* args for call_into_lisp : function*/
838 *(sp-13) = 0; /* arg array */
839 *(sp-12) = 0; /* no. args */
840 /* this order matches that used in POPAD */
841 *(sp-11)=*os_context_register_addr(context,reg_EDI);
842 *(sp-10)=*os_context_register_addr(context,reg_ESI);
844 *(sp-9)=*os_context_register_addr(context,reg_ESP)-8;
845 /* POPAD ignores the value of ESP: */
847 *(sp-7)=*os_context_register_addr(context,reg_EBX);
849 *(sp-6)=*os_context_register_addr(context,reg_EDX);
850 *(sp-5)=*os_context_register_addr(context,reg_ECX);
851 *(sp-4)=*os_context_register_addr(context,reg_EAX);
852 *(sp-3)=*context_eflags_addr(context);
853 *(sp-2)=*os_context_register_addr(context,reg_EBP);
854 *(sp-1)=*os_context_pc_addr(context);
856 #elif defined(LISP_FEATURE_X86_64)
857 u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
858 /* return address for call_into_lisp: */
859 *(sp-18) = (u64)post_signal_tramp;
861 *(sp-17)=*os_context_register_addr(context,reg_R15);
862 *(sp-16)=*os_context_register_addr(context,reg_R14);
863 *(sp-15)=*os_context_register_addr(context,reg_R13);
864 *(sp-14)=*os_context_register_addr(context,reg_R12);
865 *(sp-13)=*os_context_register_addr(context,reg_R11);
866 *(sp-12)=*os_context_register_addr(context,reg_R10);
867 *(sp-11)=*os_context_register_addr(context,reg_R9);
868 *(sp-10)=*os_context_register_addr(context,reg_R8);
869 *(sp-9)=*os_context_register_addr(context,reg_RDI);
870 *(sp-8)=*os_context_register_addr(context,reg_RSI);
871 /* skip RBP and RSP */
872 *(sp-7)=*os_context_register_addr(context,reg_RBX);
873 *(sp-6)=*os_context_register_addr(context,reg_RDX);
874 *(sp-5)=*os_context_register_addr(context,reg_RCX);
875 *(sp-4)=*os_context_register_addr(context,reg_RAX);
876 *(sp-3)=*context_eflags_addr(context);
877 *(sp-2)=*os_context_register_addr(context,reg_RBP);
878 *(sp-1)=*os_context_pc_addr(context);
880 *os_context_register_addr(context,reg_RDI) =
881 (os_context_register_t)function; /* function */
882 *os_context_register_addr(context,reg_RSI) = 0; /* arg. array */
883 *os_context_register_addr(context,reg_RDX) = 0; /* no. args */
885 struct thread *th=arch_os_get_current_thread();
886 build_fake_control_stack_frames(th,context);
889 #ifdef LISP_FEATURE_X86
890 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
891 *os_context_register_addr(context,reg_ECX) = 0;
892 *os_context_register_addr(context,reg_EBP) = (os_context_register_t)(sp-2);
894 *os_context_register_addr(context,reg_UESP) =
895 (os_context_register_t)(sp-15);
897 *os_context_register_addr(context,reg_ESP) = (os_context_register_t)(sp-15);
899 #elif defined(LISP_FEATURE_X86_64)
900 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
901 *os_context_register_addr(context,reg_RCX) = 0;
902 *os_context_register_addr(context,reg_RBP) = (os_context_register_t)(sp-2);
903 *os_context_register_addr(context,reg_RSP) = (os_context_register_t)(sp-18);
905 /* this much of the calling convention is common to all
907 *os_context_pc_addr(context) = (os_context_register_t)(unsigned long)code;
908 *os_context_register_addr(context,reg_NARGS) = 0;
909 *os_context_register_addr(context,reg_LIP) =
910 (os_context_register_t)(unsigned long)code;
911 *os_context_register_addr(context,reg_CFP) =
912 (os_context_register_t)(unsigned long)current_control_frame_pointer;
914 #ifdef ARCH_HAS_NPC_REGISTER
915 *os_context_npc_addr(context) =
916 4 + *os_context_pc_addr(context);
918 #ifdef LISP_FEATURE_SPARC
919 *os_context_register_addr(context,reg_CODE) =
920 (os_context_register_t)(fun + FUN_POINTER_LOWTAG);
924 #ifdef LISP_FEATURE_SB_THREAD
926 /* FIXME: this function can go away when all lisp handlers are invoked
927 * via arrange_return_to_lisp_function. */
929 interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
931 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
932 /* let the handler enable interrupts again when it sees fit */
933 sigaddset_deferrable(os_context_sigmask_addr(context));
934 arrange_return_to_lisp_function(context, SymbolFunction(RUN_INTERRUPTION));
939 /* KLUDGE: Theoretically the approach we use for undefined alien
940 * variables should work for functions as well, but on PPC/Darwin
941 * we get bus error at bogus addresses instead, hence this workaround,
942 * that has the added benefit of automatically discriminating between
943 * functions and variables.
946 undefined_alien_function() {
947 funcall0(SymbolFunction(UNDEFINED_ALIEN_FUNCTION_ERROR));
951 handle_guard_page_triggered(os_context_t *context,os_vm_address_t addr)
953 struct thread *th=arch_os_get_current_thread();
955 /* note the os_context hackery here. When the signal handler returns,
956 * it won't go back to what it was doing ... */
957 if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
958 addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
959 /* We hit the end of the control stack: disable guard page
960 * protection so the error handler has some headroom, protect the
961 * previous page so that we can catch returns from the guard page
963 protect_control_stack_guard_page(0);
964 protect_control_stack_return_guard_page(1);
966 arrange_return_to_lisp_function
967 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
970 else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
971 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
972 /* We're returning from the guard page: reprotect it, and
973 * unprotect this one. This works even if we somehow missed
974 * the return-guard-page, and hit it on our way to new
975 * exhaustion instead. */
976 protect_control_stack_guard_page(1);
977 protect_control_stack_return_guard_page(0);
980 else if (addr >= undefined_alien_address &&
981 addr < undefined_alien_address + os_vm_page_size) {
982 arrange_return_to_lisp_function
983 (context, SymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
989 #ifndef LISP_FEATURE_GENCGC
990 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
991 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
992 * whether the signal was due to treading on the mprotect()ed zone -
993 * and if so, arrange for a GC to happen. */
994 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
997 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
999 os_context_t *context=(os_context_t *) void_context;
1001 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
1002 struct thread *thread=arch_os_get_current_thread();
1003 clear_auto_gc_trigger();
1004 /* Don't flood the system with interrupts if the need to gc is
1005 * already noted. This can happen for example when SUB-GC
1006 * allocates or after a gc triggered in a WITHOUT-GCING. */
1007 if (SymbolValue(GC_PENDING,thread) == NIL) {
1008 if (SymbolValue(GC_INHIBIT,thread) == NIL) {
1009 if (arch_pseudo_atomic_atomic(context)) {
1010 /* set things up so that GC happens when we finish
1012 SetSymbolValue(GC_PENDING,T,thread);
1013 arch_set_pseudo_atomic_interrupted(context);
1015 interrupt_maybe_gc_int(signal,info,void_context);
1018 SetSymbolValue(GC_PENDING,T,thread);
1028 /* this is also used by gencgc, in alloc() */
1030 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
1032 os_context_t *context=(os_context_t *) void_context;
1033 #ifndef LISP_FEATURE_WIN32
1034 struct thread *thread=arch_os_get_current_thread();
1037 fake_foreign_function_call(context);
1039 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
1040 * which case we will be running with no gc trigger barrier
1041 * thing for a while. But it shouldn't be long until the end
1044 * FIXME: It would be good to protect the end of dynamic space
1045 * and signal a storage condition from there.
1048 /* Restore the signal mask from the interrupted context before
1049 * calling into Lisp if interrupts are enabled. Why not always?
1051 * Suppose there is a WITHOUT-INTERRUPTS block far, far out. If an
1052 * interrupt hits while in SUB-GC, it is deferred and the
1053 * os_context_sigmask of that interrupt is set to block further
1054 * deferrable interrupts (until the first one is
1055 * handled). Unfortunately, that context refers to this place and
1056 * when we return from here the signals will not be blocked.
1058 * A kludgy alternative is to propagate the sigmask change to the
1061 #ifndef LISP_FEATURE_WIN32
1062 if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL)
1063 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
1064 #ifdef LISP_FEATURE_SB_THREAD
1068 sigaddset(&new,SIG_STOP_FOR_GC);
1069 thread_sigmask(SIG_UNBLOCK,&new,0);
1073 funcall0(SymbolFunction(SUB_GC));
1075 undo_fake_foreign_function_call(context);
1081 * noise to install handlers
1084 #ifndef LISP_FEATURE_WIN32
1085 /* In Linux 2.4 synchronous signals (sigtrap & co) can be delivered if
1086 * they are blocked, in Linux 2.6 the default handler is invoked
1087 * instead that usually coredumps. One might hastily think that adding
1088 * SA_NODEFER helps, but until ~2.6.13 if SA_NODEFER is specified then
1089 * the whole sa_mask is ignored and instead of not adding the signal
1090 * in question to the mask. That means if it's not blockable the
1091 * signal must be unblocked at the beginning of signal handlers.
1093 * It turns out that NetBSD's SA_NODEFER doesn't DTRT in a different
1094 * way: if SA_NODEFER is set and the signal is in sa_mask, the signal
1095 * will be unblocked in the sigmask during the signal handler. -- RMK
1098 static volatile int sigaction_nodefer_works = -1;
1100 #define SA_NODEFER_TEST_BLOCK_SIGNAL SIGABRT
1101 #define SA_NODEFER_TEST_KILL_SIGNAL SIGUSR1
1104 sigaction_nodefer_test_handler(int signal, siginfo_t *info, void *void_context)
1106 sigset_t empty, current;
1108 sigemptyset(&empty);
1109 sigprocmask(SIG_BLOCK, &empty, ¤t);
1110 /* There should be exactly two blocked signals: the two we added
1111 * to sa_mask when setting up the handler. NetBSD doesn't block
1112 * the signal we're handling when SA_NODEFER is set; Linux before
1113 * 2.6.13 or so also doesn't block the other signal when
1114 * SA_NODEFER is set. */
1115 for(i = 1; i < NSIG; i++)
1116 if (sigismember(¤t, i) !=
1117 (((i == SA_NODEFER_TEST_BLOCK_SIGNAL) || (i == signal)) ? 1 : 0)) {
1118 FSHOW_SIGNAL((stderr, "SA_NODEFER doesn't work, signal %d\n", i));
1119 sigaction_nodefer_works = 0;
1121 if (sigaction_nodefer_works == -1)
1122 sigaction_nodefer_works = 1;
1126 see_if_sigaction_nodefer_works()
1128 struct sigaction sa, old_sa;
1130 sa.sa_flags = SA_SIGINFO | SA_NODEFER;
1131 sa.sa_sigaction = sigaction_nodefer_test_handler;
1132 sigemptyset(&sa.sa_mask);
1133 sigaddset(&sa.sa_mask, SA_NODEFER_TEST_BLOCK_SIGNAL);
1134 sigaddset(&sa.sa_mask, SA_NODEFER_TEST_KILL_SIGNAL);
1135 sigaction(SA_NODEFER_TEST_KILL_SIGNAL, &sa, &old_sa);
1136 /* Make sure no signals are blocked. */
1139 sigemptyset(&empty);
1140 sigprocmask(SIG_SETMASK, &empty, 0);
1142 kill(getpid(), SA_NODEFER_TEST_KILL_SIGNAL);
1143 while (sigaction_nodefer_works == -1);
1144 sigaction(SA_NODEFER_TEST_KILL_SIGNAL, &old_sa, NULL);
1147 #undef SA_NODEFER_TEST_BLOCK_SIGNAL
1148 #undef SA_NODEFER_TEST_KILL_SIGNAL
1151 unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1154 sigemptyset(&unblock);
1155 sigaddset(&unblock, signal);
1156 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1157 interrupt_handle_now_handler(signal, info, void_context);
1161 low_level_unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1164 sigemptyset(&unblock);
1165 sigaddset(&unblock, signal);
1166 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1167 (*interrupt_low_level_handlers[signal])(signal, info, void_context);
1171 undoably_install_low_level_interrupt_handler (int signal,
1176 struct sigaction sa;
1178 if (0 > signal || signal >= NSIG) {
1179 lose("bad signal number %d\n", signal);
1182 if (ARE_SAME_HANDLER(handler, SIG_DFL))
1183 sa.sa_sigaction = handler;
1184 else if (sigismember(&deferrable_sigset,signal))
1185 sa.sa_sigaction = low_level_maybe_now_maybe_later;
1186 else if (!sigaction_nodefer_works &&
1187 !sigismember(&blockable_sigset, signal))
1188 sa.sa_sigaction = low_level_unblock_me_trampoline;
1190 sa.sa_sigaction = handler;
1192 sigcopyset(&sa.sa_mask, &blockable_sigset);
1193 sa.sa_flags = SA_SIGINFO | SA_RESTART |
1194 (sigaction_nodefer_works ? SA_NODEFER : 0);
1195 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
1196 if((signal==SIG_MEMORY_FAULT)
1197 #ifdef SIG_MEMORY_FAULT2
1198 || (signal==SIG_MEMORY_FAULT2)
1200 #ifdef SIG_INTERRUPT_THREAD
1201 || (signal==SIG_INTERRUPT_THREAD)
1204 sa.sa_flags |= SA_ONSTACK;
1207 sigaction(signal, &sa, NULL);
1208 interrupt_low_level_handlers[signal] =
1209 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
1213 /* This is called from Lisp. */
1215 install_handler(int signal, void handler(int, siginfo_t*, void*))
1217 #ifndef LISP_FEATURE_WIN32
1218 struct sigaction sa;
1220 union interrupt_handler oldhandler;
1222 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
1225 sigaddset(&new, signal);
1226 thread_sigmask(SIG_BLOCK, &new, &old);
1228 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%x\n",
1229 (unsigned int)interrupt_low_level_handlers[signal]));
1230 if (interrupt_low_level_handlers[signal]==0) {
1231 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
1232 ARE_SAME_HANDLER(handler, SIG_IGN))
1233 sa.sa_sigaction = handler;
1234 else if (sigismember(&deferrable_sigset, signal))
1235 sa.sa_sigaction = maybe_now_maybe_later;
1236 else if (!sigaction_nodefer_works &&
1237 !sigismember(&blockable_sigset, signal))
1238 sa.sa_sigaction = unblock_me_trampoline;
1240 sa.sa_sigaction = interrupt_handle_now_handler;
1242 sigcopyset(&sa.sa_mask, &blockable_sigset);
1243 sa.sa_flags = SA_SIGINFO | SA_RESTART |
1244 (sigaction_nodefer_works ? SA_NODEFER : 0);
1245 sigaction(signal, &sa, NULL);
1248 oldhandler = interrupt_handlers[signal];
1249 interrupt_handlers[signal].c = handler;
1251 thread_sigmask(SIG_SETMASK, &old, 0);
1253 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
1255 return (unsigned long)oldhandler.lisp;
1257 /* Probably-wrong Win32 hack */
1265 #ifndef LISP_FEATURE_WIN32
1267 SHOW("entering interrupt_init()");
1268 see_if_sigaction_nodefer_works();
1269 sigemptyset(&deferrable_sigset);
1270 sigemptyset(&blockable_sigset);
1271 sigaddset_deferrable(&deferrable_sigset);
1272 sigaddset_blockable(&blockable_sigset);
1274 /* Set up high level handler information. */
1275 for (i = 0; i < NSIG; i++) {
1276 interrupt_handlers[i].c =
1277 /* (The cast here blasts away the distinction between
1278 * SA_SIGACTION-style three-argument handlers and
1279 * signal(..)-style one-argument handlers, which is OK
1280 * because it works to call the 1-argument form where the
1281 * 3-argument form is expected.) */
1282 (void (*)(int, siginfo_t*, void*))SIG_DFL;
1285 SHOW("returning from interrupt_init()");