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 */
48 #include <sys/types.h>
56 #include "interrupt.h"
65 #include "genesis/fdefn.h"
66 #include "genesis/simple-fun.h"
67 #include "genesis/cons.h"
71 static void run_deferred_handler(struct interrupt_data *data, void *v_context);
72 static void store_signal_data_for_later (struct interrupt_data *data,
73 void *handler, int signal,
75 os_context_t *context);
76 boolean interrupt_maybe_gc_int(int signal, siginfo_t *info, void *v_context);
79 sigaddset_deferrable(sigset_t *s)
83 sigaddset(s, SIGQUIT);
84 sigaddset(s, SIGPIPE);
85 sigaddset(s, SIGALRM);
87 sigaddset(s, SIGTSTP);
88 sigaddset(s, SIGCHLD);
90 sigaddset(s, SIGXCPU);
91 sigaddset(s, SIGXFSZ);
92 sigaddset(s, SIGVTALRM);
93 sigaddset(s, SIGPROF);
94 sigaddset(s, SIGWINCH);
95 sigaddset(s, SIGUSR1);
96 sigaddset(s, SIGUSR2);
97 #ifdef LISP_FEATURE_SB_THREAD
98 sigaddset(s, SIG_INTERRUPT_THREAD);
103 sigaddset_blockable(sigset_t *s)
105 sigaddset_deferrable(s);
106 #ifdef LISP_FEATURE_SB_THREAD
107 sigaddset(s, SIG_STOP_FOR_GC);
111 /* initialized in interrupt_init */
112 static sigset_t deferrable_sigset;
113 static sigset_t blockable_sigset;
116 check_blockables_blocked_or_lose()
118 /* Get the current sigmask, by blocking the empty set. */
119 sigset_t empty,current;
122 thread_sigmask(SIG_BLOCK, &empty, ¤t);
123 for(i = 1; i < NSIG; i++) {
124 if (sigismember(&blockable_sigset, i) && !sigismember(¤t, i))
125 lose("blockable signal %d not blocked\n",i);
130 check_interrupts_enabled_or_lose(os_context_t *context)
132 struct thread *thread=arch_os_get_current_thread();
133 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL)
134 lose("interrupts not enabled\n");
136 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
137 (!foreign_function_call_active) &&
139 arch_pseudo_atomic_atomic(context))
140 lose ("in pseudo atomic section\n");
143 /* When we catch an internal error, should we pass it back to Lisp to
144 * be handled in a high-level way? (Early in cold init, the answer is
145 * 'no', because Lisp is still too brain-dead to handle anything.
146 * After sufficient initialization has been completed, the answer
148 boolean internal_errors_enabled = 0;
150 static void (*interrupt_low_level_handlers[NSIG]) (int, siginfo_t*, void*);
151 union interrupt_handler interrupt_handlers[NSIG];
153 /* At the toplevel repl we routinely call this function. The signal
154 * mask ought to be clear anyway most of the time, but may be non-zero
155 * if we were interrupted e.g. while waiting for a queue. */
158 reset_signal_mask(void)
162 thread_sigmask(SIG_SETMASK,&new,0);
166 block_blockable_signals(void)
168 thread_sigmask(SIG_BLOCK, &blockable_sigset, 0);
173 * utility routines used by various signal handlers
177 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
179 #ifndef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
183 /* Build a fake stack frame or frames */
185 current_control_frame_pointer =
186 (lispobj *)(unsigned long)
187 (*os_context_register_addr(context, reg_CSP));
188 if ((lispobj *)(unsigned long)
189 (*os_context_register_addr(context, reg_CFP))
190 == current_control_frame_pointer) {
191 /* There is a small window during call where the callee's
192 * frame isn't built yet. */
193 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
194 == FUN_POINTER_LOWTAG) {
195 /* We have called, but not built the new frame, so
196 * build it for them. */
197 current_control_frame_pointer[0] =
198 *os_context_register_addr(context, reg_OCFP);
199 current_control_frame_pointer[1] =
200 *os_context_register_addr(context, reg_LRA);
201 current_control_frame_pointer += 8;
202 /* Build our frame on top of it. */
203 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
206 /* We haven't yet called, build our frame as if the
207 * partial frame wasn't there. */
208 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
211 /* We can't tell whether we are still in the caller if it had to
212 * allocate a stack frame due to stack arguments. */
213 /* This observation provoked some past CMUCL maintainer to ask
214 * "Can anything strange happen during return?" */
217 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
220 current_control_stack_pointer = current_control_frame_pointer + 8;
222 current_control_frame_pointer[0] = oldcont;
223 current_control_frame_pointer[1] = NIL;
224 current_control_frame_pointer[2] =
225 (lispobj)(*os_context_register_addr(context, reg_CODE));
229 /* Stores the context for gc to scavange and builds fake stack
232 fake_foreign_function_call(os_context_t *context)
235 struct thread *thread=arch_os_get_current_thread();
237 /* context_index incrementing must not be interrupted */
238 check_blockables_blocked_or_lose();
240 /* Get current Lisp state from context. */
242 dynamic_space_free_pointer =
243 (lispobj *)(unsigned long)
244 (*os_context_register_addr(context, reg_ALLOC));
245 #if defined(LISP_FEATURE_ALPHA)
246 if ((long)dynamic_space_free_pointer & 1) {
247 lose("dead in fake_foreign_function_call, context = %x\n", context);
252 current_binding_stack_pointer =
253 (lispobj *)(unsigned long)
254 (*os_context_register_addr(context, reg_BSP));
257 build_fake_control_stack_frames(thread,context);
259 /* Do dynamic binding of the active interrupt context index
260 * and save the context in the context array. */
262 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
264 if (context_index >= MAX_INTERRUPTS) {
265 lose("maximum interrupt nesting depth (%d) exceeded\n", MAX_INTERRUPTS);
268 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
269 make_fixnum(context_index + 1),thread);
271 thread->interrupt_contexts[context_index] = context;
273 /* no longer in Lisp now */
274 foreign_function_call_active = 1;
277 /* blocks all blockable signals. If you are calling from a signal handler,
278 * the usual signal mask will be restored from the context when the handler
279 * finishes. Otherwise, be careful */
281 undo_fake_foreign_function_call(os_context_t *context)
283 struct thread *thread=arch_os_get_current_thread();
284 /* Block all blockable signals. */
285 block_blockable_signals();
287 /* going back into Lisp */
288 foreign_function_call_active = 0;
290 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
294 /* Put the dynamic space free pointer back into the context. */
295 *os_context_register_addr(context, reg_ALLOC) =
296 (unsigned long) dynamic_space_free_pointer;
300 /* a handler for the signal caused by execution of a trap opcode
301 * signalling an internal error */
303 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
308 fake_foreign_function_call(context);
310 if (!internal_errors_enabled) {
311 describe_internal_error(context);
312 /* There's no good way to recover from an internal error
313 * before the Lisp error handling mechanism is set up. */
314 lose("internal error too early in init, can't recover\n");
317 /* Allocate the SAP object while the interrupts are still
319 context_sap = alloc_sap(context);
321 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
323 SHOW("in interrupt_internal_error");
325 /* Display some rudimentary debugging information about the
326 * error, so that even if the Lisp error handler gets badly
327 * confused, we have a chance to determine what's going on. */
328 describe_internal_error(context);
330 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
331 continuable ? T : NIL);
333 undo_fake_foreign_function_call(context); /* blocks signals again */
335 arch_skip_instruction(context);
339 interrupt_handle_pending(os_context_t *context)
341 struct thread *thread;
342 struct interrupt_data *data;
344 check_blockables_blocked_or_lose();
346 thread=arch_os_get_current_thread();
347 data=thread->interrupt_data;
349 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
350 /* If pseudo_atomic_interrupted is set then the interrupt is going
351 * to be handled now, ergo it's safe to clear it. */
352 arch_clear_pseudo_atomic_interrupted(context);
355 if (SymbolValue(GC_INHIBIT,thread)==NIL) {
356 #ifdef LISP_FEATURE_SB_THREAD
357 if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
358 /* another thread has already initiated a gc, this attempt
359 * might as well be cancelled */
360 SetSymbolValue(GC_PENDING,NIL,thread);
361 SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
362 sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
365 if (SymbolValue(GC_PENDING,thread) != NIL) {
366 /* GC_PENDING is cleared in SUB-GC, or if another thread
367 * is doing a gc already we will get a SIG_STOP_FOR_GC and
368 * that will clear it. */
369 interrupt_maybe_gc_int(0,NULL,context);
371 check_blockables_blocked_or_lose();
374 /* we may be here only to do the gc stuff, if interrupts are
375 * enabled run the pending handler */
376 if (!((SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) ||
378 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
379 (!foreign_function_call_active) &&
381 arch_pseudo_atomic_atomic(context)))) {
383 /* There may be no pending handler, because it was only a gc
384 * that had to be executed or because pseudo atomic triggered
385 * twice for a single interrupt. For the interested reader,
386 * that may happen if an interrupt hits after the interrupted
387 * flag is cleared but before pseduo-atomic is set and a
388 * pseudo atomic is interrupted in that interrupt. */
389 if (data->pending_handler) {
391 /* If we're here as the result of a pseudo-atomic as opposed
392 * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
393 * NIL, because maybe_defer_handler sets
394 * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
395 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
397 /* restore the saved signal mask from the original signal (the
398 * one that interrupted us during the critical section) into the
399 * os_context for the signal we're currently in the handler for.
400 * This should ensure that when we return from the handler the
401 * blocked signals are unblocked */
402 sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
404 sigemptyset(&data->pending_mask);
405 /* This will break on sparc linux: the deferred handler really wants
406 * to be called with a void_context */
407 run_deferred_handler(data,(void *)context);
413 * the two main signal handlers:
414 * interrupt_handle_now(..)
415 * maybe_now_maybe_later(..)
417 * to which we have added interrupt_handle_now_handler(..). Why?
418 * Well, mostly because the SPARC/Linux platform doesn't quite do
419 * signals the way we want them done. The third argument in the
420 * handler isn't filled in by the kernel properly, so we fix it up
421 * ourselves in the arch_os_get_context(..) function; however, we only
422 * want to do this when we first hit the handler, and not when
423 * interrupt_handle_now(..) is being called from some other handler
424 * (when the fixup will already have been done). -- CSR, 2002-07-23
428 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
430 os_context_t *context = (os_context_t*)void_context;
431 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
432 boolean were_in_lisp;
434 union interrupt_handler handler;
435 check_blockables_blocked_or_lose();
436 if (sigismember(&deferrable_sigset,signal))
437 check_interrupts_enabled_or_lose(context);
439 #ifdef LISP_FEATURE_LINUX
440 /* Under Linux on some architectures, we appear to have to restore
441 the FPU control word from the context, as after the signal is
442 delivered we appear to have a null FPU control word. */
443 os_restore_fp_control(context);
445 handler = interrupt_handlers[signal];
447 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
451 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
452 were_in_lisp = !foreign_function_call_active;
456 fake_foreign_function_call(context);
459 FSHOW_SIGNAL((stderr,
460 "/entering interrupt_handle_now(%d, info, context)\n",
463 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
465 /* This can happen if someone tries to ignore or default one
466 * of the signals we need for runtime support, and the runtime
467 * support decides to pass on it. */
468 lose("no handler for signal %d in interrupt_handle_now(..)\n", signal);
470 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
471 /* Once we've decided what to do about contexts in a
472 * return-elsewhere world (the original context will no longer
473 * be available; should we copy it or was nobody using it anyway?)
474 * then we should convert this to return-elsewhere */
476 /* CMUCL comment said "Allocate the SAPs while the interrupts
477 * are still disabled.". I (dan, 2003.08.21) assume this is
478 * because we're not in pseudoatomic and allocation shouldn't
479 * be interrupted. In which case it's no longer an issue as
480 * all our allocation from C now goes through a PA wrapper,
481 * but still, doesn't hurt.
483 * Yeah, but non-gencgc platforms don't really wrap allocation
484 * in PA. MG - 2005-08-29 */
486 lispobj info_sap,context_sap = alloc_sap(context);
487 info_sap = alloc_sap(info);
488 /* Leave deferrable signals blocked, the handler itself will
489 * allow signals again when it sees fit. */
490 #ifdef LISP_FEATURE_SB_THREAD
493 sigemptyset(&unblock);
494 sigaddset(&unblock, SIG_STOP_FOR_GC);
495 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
499 FSHOW_SIGNAL((stderr,"/calling Lisp-level handler\n"));
501 funcall3(handler.lisp,
507 FSHOW_SIGNAL((stderr,"/calling C-level handler\n"));
509 /* Allow signals again. */
510 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
512 (*handler.c)(signal, info, void_context);
515 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
519 undo_fake_foreign_function_call(context); /* block signals again */
522 FSHOW_SIGNAL((stderr,
523 "/returning from interrupt_handle_now(%d, info, context)\n",
527 /* This is called at the end of a critical section if the indications
528 * are that some signal was deferred during the section. Note that as
529 * far as C or the kernel is concerned we dealt with the signal
530 * already; we're just doing the Lisp-level processing now that we
533 run_deferred_handler(struct interrupt_data *data, void *v_context) {
534 /* The pending_handler may enable interrupts and then another
535 * interrupt may hit, overwrite interrupt_data, so reset the
536 * pending handler before calling it. Trust the handler to finish
537 * with the siginfo before enabling interrupts. */
538 void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
539 data->pending_handler=0;
540 (*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
544 maybe_defer_handler(void *handler, struct interrupt_data *data,
545 int signal, siginfo_t *info, os_context_t *context)
547 struct thread *thread=arch_os_get_current_thread();
549 check_blockables_blocked_or_lose();
551 if (SymbolValue(INTERRUPT_PENDING,thread) != NIL)
552 lose("interrupt already pending\n");
553 /* If interrupts are disabled then INTERRUPT_PENDING is set and
554 * not PSEDUO_ATOMIC_INTERRUPTED. This is important for a pseudo
555 * atomic section inside a WITHOUT-INTERRUPTS.
557 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
558 store_signal_data_for_later(data,handler,signal,info,context);
559 SetSymbolValue(INTERRUPT_PENDING, T,thread);
560 FSHOW_SIGNAL((stderr,
561 "/maybe_defer_handler(%x,%d),thread=%lu: deferred\n",
562 (unsigned int)handler,signal,
563 (unsigned long)thread->os_thread));
566 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
567 * actually use its argument for anything on x86, so this branch
568 * may succeed even when context is null (gencgc alloc()) */
570 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
571 /* FIXME: this foreign_function_call_active test is dubious at
572 * best. If a foreign call is made in a pseudo atomic section
573 * (?) or more likely a pseudo atomic section is in a foreign
574 * call then an interrupt is executed immediately. Maybe it
575 * has to do with C code not maintaining pseudo atomic
576 * properly. MG - 2005-08-10 */
577 (!foreign_function_call_active) &&
579 arch_pseudo_atomic_atomic(context)) {
580 store_signal_data_for_later(data,handler,signal,info,context);
581 arch_set_pseudo_atomic_interrupted(context);
582 FSHOW_SIGNAL((stderr,
583 "/maybe_defer_handler(%x,%d),thread=%lu: deferred(PA)\n",
584 (unsigned int)handler,signal,
585 (unsigned long)thread->os_thread));
588 FSHOW_SIGNAL((stderr,
589 "/maybe_defer_handler(%x,%d),thread=%lu: not deferred\n",
590 (unsigned int)handler,signal,
591 (unsigned long)thread->os_thread));
596 store_signal_data_for_later (struct interrupt_data *data, void *handler,
598 siginfo_t *info, os_context_t *context)
600 if (data->pending_handler)
601 lose("tried to overwrite pending interrupt handler %x with %x\n",
602 data->pending_handler, handler);
604 lose("tried to defer null interrupt handler\n");
605 data->pending_handler = handler;
606 data->pending_signal = signal;
608 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
610 /* the signal mask in the context (from before we were
611 * interrupted) is copied to be restored when
612 * run_deferred_handler happens. Then the usually-blocked
613 * signals are added to the mask in the context so that we are
614 * running with blocked signals when the handler returns */
615 sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
616 sigaddset_deferrable(os_context_sigmask_addr(context));
621 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
623 os_context_t *context = arch_os_get_context(&void_context);
624 struct thread *thread=arch_os_get_current_thread();
625 struct interrupt_data *data=thread->interrupt_data;
626 #ifdef LISP_FEATURE_LINUX
627 os_restore_fp_control(context);
629 if(maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
631 interrupt_handle_now(signal, info, context);
632 #ifdef LISP_FEATURE_DARWIN
633 /* Work around G5 bug */
634 DARWIN_FIX_CONTEXT(context);
639 low_level_interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
641 os_context_t *context = (os_context_t*)void_context;
643 #ifdef LISP_FEATURE_LINUX
644 os_restore_fp_control(context);
646 check_blockables_blocked_or_lose();
647 check_interrupts_enabled_or_lose(context);
648 interrupt_low_level_handlers[signal](signal, info, void_context);
649 #ifdef LISP_FEATURE_DARWIN
650 /* Work around G5 bug */
651 DARWIN_FIX_CONTEXT(context);
656 low_level_maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
658 os_context_t *context = arch_os_get_context(&void_context);
659 struct thread *thread=arch_os_get_current_thread();
660 struct interrupt_data *data=thread->interrupt_data;
661 #ifdef LISP_FEATURE_LINUX
662 os_restore_fp_control(context);
664 if(maybe_defer_handler(low_level_interrupt_handle_now,data,
665 signal,info,context))
667 low_level_interrupt_handle_now(signal, info, context);
668 #ifdef LISP_FEATURE_DARWIN
669 /* Work around G5 bug */
670 DARWIN_FIX_CONTEXT(context);
674 #ifdef LISP_FEATURE_SB_THREAD
677 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
679 os_context_t *context = arch_os_get_context(&void_context);
680 struct thread *thread=arch_os_get_current_thread();
683 if ((arch_pseudo_atomic_atomic(context) ||
684 SymbolValue(GC_INHIBIT,thread) != NIL)) {
685 SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
686 if (SymbolValue(GC_INHIBIT,thread) == NIL)
687 arch_set_pseudo_atomic_interrupted(context);
688 FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred\n",
691 /* need the context stored so it can have registers scavenged */
692 fake_foreign_function_call(context);
694 sigfillset(&ss); /* Block everything. */
695 thread_sigmask(SIG_BLOCK,&ss,0);
697 if(thread->state!=STATE_RUNNING) {
698 lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
699 fixnum_value(thread->state));
701 thread->state=STATE_SUSPENDED;
702 FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
704 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
705 /* It is possible to get SIGCONT (and probably other
706 * non-blockable signals) here. */
707 while (sigwaitinfo(&ss,0) != SIG_STOP_FOR_GC);
708 FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
709 if(thread->state!=STATE_RUNNING) {
710 lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
711 fixnum_value(thread->state));
714 undo_fake_foreign_function_call(context);
720 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
722 os_context_t *context = arch_os_get_context(&void_context);
723 interrupt_handle_now(signal, info, context);
724 #ifdef LISP_FEATURE_DARWIN
725 DARWIN_FIX_CONTEXT(context);
730 * stuff to detect and handle hitting the GC trigger
733 #ifndef LISP_FEATURE_GENCGC
734 /* since GENCGC has its own way to record trigger */
736 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
738 if (current_auto_gc_trigger == NULL)
741 void *badaddr=arch_get_bad_addr(signal,info,context);
742 return (badaddr >= (void *)current_auto_gc_trigger &&
743 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
748 /* manipulate the signal context and stack such that when the handler
749 * returns, it will call function instead of whatever it was doing
753 #if (defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
754 extern int *context_eflags_addr(os_context_t *context);
757 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
758 extern void post_signal_tramp(void);
760 arrange_return_to_lisp_function(os_context_t *context, lispobj function)
762 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
763 void * fun=native_pointer(function);
764 void *code = &(((struct simple_fun *) fun)->code);
767 /* Build a stack frame showing `interrupted' so that the
768 * user's backtrace makes (as much) sense (as usual) */
770 /* FIXME: what about restoring fp state? */
771 /* FIXME: what about restoring errno? */
772 #ifdef LISP_FEATURE_X86
773 /* Suppose the existence of some function that saved all
774 * registers, called call_into_lisp, then restored GP registers and
775 * returned. It would look something like this:
783 pushl {address of function to call}
784 call 0x8058db0 <call_into_lisp>
791 * What we do here is set up the stack that call_into_lisp would
792 * expect to see if it had been called by this code, and frob the
793 * signal context so that signal return goes directly to call_into_lisp,
794 * and when that function (and the lisp function it invoked) returns,
795 * it returns to the second half of this imaginary function which
796 * restores all registers and returns to C
798 * For this to work, the latter part of the imaginary function
799 * must obviously exist in reality. That would be post_signal_tramp
802 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
804 /* return address for call_into_lisp: */
805 *(sp-15) = (u32)post_signal_tramp;
806 *(sp-14) = function; /* args for call_into_lisp : function*/
807 *(sp-13) = 0; /* arg array */
808 *(sp-12) = 0; /* no. args */
809 /* this order matches that used in POPAD */
810 *(sp-11)=*os_context_register_addr(context,reg_EDI);
811 *(sp-10)=*os_context_register_addr(context,reg_ESI);
813 *(sp-9)=*os_context_register_addr(context,reg_ESP)-8;
814 /* POPAD ignores the value of ESP: */
816 *(sp-7)=*os_context_register_addr(context,reg_EBX);
818 *(sp-6)=*os_context_register_addr(context,reg_EDX);
819 *(sp-5)=*os_context_register_addr(context,reg_ECX);
820 *(sp-4)=*os_context_register_addr(context,reg_EAX);
821 *(sp-3)=*context_eflags_addr(context);
822 *(sp-2)=*os_context_register_addr(context,reg_EBP);
823 *(sp-1)=*os_context_pc_addr(context);
825 #elif defined(LISP_FEATURE_X86_64)
826 u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
827 /* return address for call_into_lisp: */
828 *(sp-18) = (u64)post_signal_tramp;
830 *(sp-17)=*os_context_register_addr(context,reg_R15);
831 *(sp-16)=*os_context_register_addr(context,reg_R14);
832 *(sp-15)=*os_context_register_addr(context,reg_R13);
833 *(sp-14)=*os_context_register_addr(context,reg_R12);
834 *(sp-13)=*os_context_register_addr(context,reg_R11);
835 *(sp-12)=*os_context_register_addr(context,reg_R10);
836 *(sp-11)=*os_context_register_addr(context,reg_R9);
837 *(sp-10)=*os_context_register_addr(context,reg_R8);
838 *(sp-9)=*os_context_register_addr(context,reg_RDI);
839 *(sp-8)=*os_context_register_addr(context,reg_RSI);
840 /* skip RBP and RSP */
841 *(sp-7)=*os_context_register_addr(context,reg_RBX);
842 *(sp-6)=*os_context_register_addr(context,reg_RDX);
843 *(sp-5)=*os_context_register_addr(context,reg_RCX);
844 *(sp-4)=*os_context_register_addr(context,reg_RAX);
845 *(sp-3)=*context_eflags_addr(context);
846 *(sp-2)=*os_context_register_addr(context,reg_RBP);
847 *(sp-1)=*os_context_pc_addr(context);
849 *os_context_register_addr(context,reg_RDI) =
850 (os_context_register_t)function; /* function */
851 *os_context_register_addr(context,reg_RSI) = 0; /* arg. array */
852 *os_context_register_addr(context,reg_RDX) = 0; /* no. args */
854 struct thread *th=arch_os_get_current_thread();
855 build_fake_control_stack_frames(th,context);
858 #ifdef LISP_FEATURE_X86
859 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
860 *os_context_register_addr(context,reg_ECX) = 0;
861 *os_context_register_addr(context,reg_EBP) = (os_context_register_t)(sp-2);
863 *os_context_register_addr(context,reg_UESP) =
864 (os_context_register_t)(sp-15);
866 *os_context_register_addr(context,reg_ESP) = (os_context_register_t)(sp-15);
868 #elif defined(LISP_FEATURE_X86_64)
869 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
870 *os_context_register_addr(context,reg_RCX) = 0;
871 *os_context_register_addr(context,reg_RBP) = (os_context_register_t)(sp-2);
872 *os_context_register_addr(context,reg_RSP) = (os_context_register_t)(sp-18);
874 /* this much of the calling convention is common to all
876 *os_context_pc_addr(context) = (os_context_register_t)(unsigned long)code;
877 *os_context_register_addr(context,reg_NARGS) = 0;
878 *os_context_register_addr(context,reg_LIP) =
879 (os_context_register_t)(unsigned long)code;
880 *os_context_register_addr(context,reg_CFP) =
881 (os_context_register_t)(unsigned long)current_control_frame_pointer;
883 #ifdef ARCH_HAS_NPC_REGISTER
884 *os_context_npc_addr(context) =
885 4 + *os_context_pc_addr(context);
887 #ifdef LISP_FEATURE_SPARC
888 *os_context_register_addr(context,reg_CODE) =
889 (os_context_register_t)(fun + FUN_POINTER_LOWTAG);
893 #ifdef LISP_FEATURE_SB_THREAD
895 /* FIXME: this function can go away when all lisp handlers are invoked
896 * via arrange_return_to_lisp_function. */
898 interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
900 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
901 /* let the handler enable interrupts again when it sees fit */
902 sigaddset_deferrable(os_context_sigmask_addr(context));
903 arrange_return_to_lisp_function(context, SymbolFunction(RUN_INTERRUPTION));
908 /* KLUDGE: Theoretically the approach we use for undefined alien
909 * variables should work for functions as well, but on PPC/Darwin
910 * we get bus error at bogus addresses instead, hence this workaround,
911 * that has the added benefit of automatically discriminating between
912 * functions and variables.
915 undefined_alien_function() {
916 funcall0(SymbolFunction(UNDEFINED_ALIEN_FUNCTION_ERROR));
920 handle_guard_page_triggered(os_context_t *context,os_vm_address_t addr)
922 struct thread *th=arch_os_get_current_thread();
924 /* note the os_context hackery here. When the signal handler returns,
925 * it won't go back to what it was doing ... */
926 if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
927 addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
928 /* We hit the end of the control stack: disable guard page
929 * protection so the error handler has some headroom, protect the
930 * previous page so that we can catch returns from the guard page
932 protect_control_stack_guard_page(0);
933 protect_control_stack_return_guard_page(1);
935 arrange_return_to_lisp_function
936 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
939 else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
940 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
941 /* We're returning from the guard page: reprotect it, and
942 * unprotect this one. This works even if we somehow missed
943 * the return-guard-page, and hit it on our way to new
944 * exhaustion instead. */
945 protect_control_stack_guard_page(1);
946 protect_control_stack_return_guard_page(0);
949 else if (addr >= undefined_alien_address &&
950 addr < undefined_alien_address + os_vm_page_size) {
951 arrange_return_to_lisp_function
952 (context, SymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
958 #ifndef LISP_FEATURE_GENCGC
959 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
960 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
961 * whether the signal was due to treading on the mprotect()ed zone -
962 * and if so, arrange for a GC to happen. */
963 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
966 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
968 os_context_t *context=(os_context_t *) void_context;
970 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
971 struct thread *thread=arch_os_get_current_thread();
972 clear_auto_gc_trigger();
973 /* Don't flood the system with interrupts if the need to gc is
974 * already noted. This can happen for example when SUB-GC
975 * allocates or after a gc triggered in a WITHOUT-GCING. */
976 if (SymbolValue(GC_PENDING,thread) == NIL) {
977 if (SymbolValue(GC_INHIBIT,thread) == NIL) {
978 if (arch_pseudo_atomic_atomic(context)) {
979 /* set things up so that GC happens when we finish
981 SetSymbolValue(GC_PENDING,T,thread);
982 arch_set_pseudo_atomic_interrupted(context);
984 interrupt_maybe_gc_int(signal,info,void_context);
987 SetSymbolValue(GC_PENDING,T,thread);
997 /* this is also used by gencgc, in alloc() */
999 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
1001 os_context_t *context=(os_context_t *) void_context;
1002 struct thread *thread=arch_os_get_current_thread();
1004 fake_foreign_function_call(context);
1006 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
1007 * which case we will be running with no gc trigger barrier
1008 * thing for a while. But it shouldn't be long until the end
1011 * FIXME: It would be good to protect the end of dynamic space
1012 * and signal a storage condition from there.
1015 /* Restore the signal mask from the interrupted context before
1016 * calling into Lisp if interrupts are enabled. Why not always?
1018 * Suppose there is a WITHOUT-INTERRUPTS block far, far out. If an
1019 * interrupt hits while in SUB-GC, it is deferred and the
1020 * os_context_sigmask of that interrupt is set to block further
1021 * deferrable interrupts (until the first one is
1022 * handled). Unfortunately, that context refers to this place and
1023 * when we return from here the signals will not be blocked.
1025 * A kludgy alternative is to propagate the sigmask change to the
1028 if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL)
1029 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
1030 #ifdef LISP_FEATURE_SB_THREAD
1034 sigaddset(&new,SIG_STOP_FOR_GC);
1035 thread_sigmask(SIG_UNBLOCK,&new,0);
1038 funcall0(SymbolFunction(SUB_GC));
1040 undo_fake_foreign_function_call(context);
1046 * noise to install handlers
1049 /* In Linux 2.4 synchronous signals (sigtrap & co) can be delivered if
1050 * they are blocked, in Linux 2.6 the default handler is invoked
1051 * instead that usually coredumps. One might hastily think that adding
1052 * SA_NODEFER helps, but until ~2.6.13 if SA_NODEFER is specified then
1053 * the whole sa_mask is ignored and instead of not adding the signal
1054 * in question to the mask. That means if it's not blockable the
1055 * signal must be unblocked at the beginning of signal handlers.
1057 static volatile int sigaction_nodefer_works = -1;
1060 sigaction_nodefer_test_handler(int signal, siginfo_t *info, void *void_context)
1062 sigset_t empty, current;
1064 sigemptyset(&empty);
1065 sigprocmask(SIG_BLOCK, &empty, ¤t);
1066 for(i = 1; i < NSIG; i++)
1067 if (sigismember(¤t, i) != ((i == SIGABRT) ? 1 : 0)) {
1068 FSHOW_SIGNAL((stderr, "SA_NODEFER doesn't work, signal %d\n", i));
1069 sigaction_nodefer_works = 0;
1071 if (sigaction_nodefer_works == -1)
1072 sigaction_nodefer_works = 1;
1076 see_if_sigaction_nodefer_works()
1078 struct sigaction sa, old_sa;
1080 sa.sa_flags = SA_SIGINFO | SA_NODEFER;
1081 sa.sa_sigaction = sigaction_nodefer_test_handler;
1082 sigemptyset(&sa.sa_mask);
1083 sigaddset(&sa.sa_mask, SIGABRT);
1084 sigaction(SIGUSR1, &sa, &old_sa);
1085 /* Make sure no signals are blocked. */
1088 sigemptyset(&empty);
1089 sigprocmask(SIG_SETMASK, &empty, 0);
1091 kill(getpid(), SIGUSR1);
1092 while (sigaction_nodefer_works == -1);
1093 sigaction(SIGUSR1, &old_sa, NULL);
1097 unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1100 sigemptyset(&unblock);
1101 sigaddset(&unblock, signal);
1102 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1103 interrupt_handle_now_handler(signal, info, void_context);
1107 low_level_unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1110 sigemptyset(&unblock);
1111 sigaddset(&unblock, signal);
1112 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1113 (*interrupt_low_level_handlers[signal])(signal, info, void_context);
1117 undoably_install_low_level_interrupt_handler (int signal,
1122 struct sigaction sa;
1124 if (0 > signal || signal >= NSIG) {
1125 lose("bad signal number %d\n", signal);
1128 if (ARE_SAME_HANDLER(handler, SIG_DFL))
1129 sa.sa_sigaction = handler;
1130 else if (sigismember(&deferrable_sigset,signal))
1131 sa.sa_sigaction = low_level_maybe_now_maybe_later;
1132 else if (!sigaction_nodefer_works &&
1133 !sigismember(&blockable_sigset, signal))
1134 sa.sa_sigaction = low_level_unblock_me_trampoline;
1136 sa.sa_sigaction = handler;
1138 sigcopyset(&sa.sa_mask, &blockable_sigset);
1139 sa.sa_flags = SA_SIGINFO | SA_RESTART |
1140 (sigaction_nodefer_works ? SA_NODEFER : 0);
1141 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
1142 if((signal==SIG_MEMORY_FAULT)
1143 #ifdef SIG_INTERRUPT_THREAD
1144 || (signal==SIG_INTERRUPT_THREAD)
1147 sa.sa_flags |= SA_ONSTACK;
1150 sigaction(signal, &sa, NULL);
1151 interrupt_low_level_handlers[signal] =
1152 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
1155 /* This is called from Lisp. */
1157 install_handler(int signal, void handler(int, siginfo_t*, void*))
1159 struct sigaction sa;
1161 union interrupt_handler oldhandler;
1163 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
1166 sigaddset(&new, signal);
1167 thread_sigmask(SIG_BLOCK, &new, &old);
1169 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%x\n",
1170 (unsigned int)interrupt_low_level_handlers[signal]));
1171 if (interrupt_low_level_handlers[signal]==0) {
1172 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
1173 ARE_SAME_HANDLER(handler, SIG_IGN))
1174 sa.sa_sigaction = handler;
1175 else if (sigismember(&deferrable_sigset, signal))
1176 sa.sa_sigaction = maybe_now_maybe_later;
1177 else if (!sigaction_nodefer_works &&
1178 !sigismember(&blockable_sigset, signal))
1179 sa.sa_sigaction = unblock_me_trampoline;
1181 sa.sa_sigaction = interrupt_handle_now_handler;
1183 sigcopyset(&sa.sa_mask, &blockable_sigset);
1184 sa.sa_flags = SA_SIGINFO | SA_RESTART |
1185 (sigaction_nodefer_works ? SA_NODEFER : 0);
1186 sigaction(signal, &sa, NULL);
1189 oldhandler = interrupt_handlers[signal];
1190 interrupt_handlers[signal].c = handler;
1192 thread_sigmask(SIG_SETMASK, &old, 0);
1194 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
1196 return (unsigned long)oldhandler.lisp;
1203 SHOW("entering interrupt_init()");
1204 see_if_sigaction_nodefer_works();
1205 sigemptyset(&deferrable_sigset);
1206 sigemptyset(&blockable_sigset);
1207 sigaddset_deferrable(&deferrable_sigset);
1208 sigaddset_blockable(&blockable_sigset);
1210 /* Set up high level handler information. */
1211 for (i = 0; i < NSIG; i++) {
1212 interrupt_handlers[i].c =
1213 /* (The cast here blasts away the distinction between
1214 * SA_SIGACTION-style three-argument handlers and
1215 * signal(..)-style one-argument handlers, which is OK
1216 * because it works to call the 1-argument form where the
1217 * 3-argument form is expected.) */
1218 (void (*)(int, siginfo_t*, void*))SIG_DFL;
1221 SHOW("returning from interrupt_init()");