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);
99 #if !((defined(LISP_FEATURE_DARWIN) || defined(LISP_FEATURE_FREEBSD)) && defined(LISP_FEATURE_SB_THREAD))
100 sigaddset(s, SIGUSR1);
101 sigaddset(s, SIGUSR2);
104 #ifdef LISP_FEATURE_SB_THREAD
105 sigaddset(s, SIG_INTERRUPT_THREAD);
110 sigaddset_blockable(sigset_t *s)
112 sigaddset_deferrable(s);
113 #ifdef LISP_FEATURE_SB_THREAD
114 #ifdef SIG_RESUME_FROM_GC
115 sigaddset(s, SIG_RESUME_FROM_GC);
117 sigaddset(s, SIG_STOP_FOR_GC);
121 /* initialized in interrupt_init */
122 static sigset_t deferrable_sigset;
123 static sigset_t blockable_sigset;
127 check_blockables_blocked_or_lose()
129 #ifndef LISP_FEATURE_WIN32
130 /* Get the current sigmask, by blocking the empty set. */
131 sigset_t empty,current;
134 thread_sigmask(SIG_BLOCK, &empty, ¤t);
135 for(i = 1; i < NSIG; i++) {
136 if (sigismember(&blockable_sigset, i) && !sigismember(¤t, i))
137 lose("blockable signal %d not blocked\n",i);
143 check_interrupts_enabled_or_lose(os_context_t *context)
145 struct thread *thread=arch_os_get_current_thread();
146 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL)
147 lose("interrupts not enabled\n");
149 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
150 (!foreign_function_call_active) &&
152 arch_pseudo_atomic_atomic(context))
153 lose ("in pseudo atomic section\n");
156 /* When we catch an internal error, should we pass it back to Lisp to
157 * be handled in a high-level way? (Early in cold init, the answer is
158 * 'no', because Lisp is still too brain-dead to handle anything.
159 * After sufficient initialization has been completed, the answer
161 boolean internal_errors_enabled = 0;
163 #ifndef LISP_FEATURE_WIN32
164 static void (*interrupt_low_level_handlers[NSIG]) (int, siginfo_t*, void*);
166 union interrupt_handler interrupt_handlers[NSIG];
168 /* At the toplevel repl we routinely call this function. The signal
169 * mask ought to be clear anyway most of the time, but may be non-zero
170 * if we were interrupted e.g. while waiting for a queue. */
173 reset_signal_mask(void)
175 #ifndef LISP_FEATURE_WIN32
178 thread_sigmask(SIG_SETMASK,&new,0);
183 block_blockable_signals(void)
185 #ifndef LISP_FEATURE_WIN32
186 thread_sigmask(SIG_BLOCK, &blockable_sigset, 0);
192 * utility routines used by various signal handlers
196 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
198 #ifndef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
202 /* Build a fake stack frame or frames */
204 current_control_frame_pointer =
205 (lispobj *)(unsigned long)
206 (*os_context_register_addr(context, reg_CSP));
207 if ((lispobj *)(unsigned long)
208 (*os_context_register_addr(context, reg_CFP))
209 == current_control_frame_pointer) {
210 /* There is a small window during call where the callee's
211 * frame isn't built yet. */
212 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
213 == FUN_POINTER_LOWTAG) {
214 /* We have called, but not built the new frame, so
215 * build it for them. */
216 current_control_frame_pointer[0] =
217 *os_context_register_addr(context, reg_OCFP);
218 current_control_frame_pointer[1] =
219 *os_context_register_addr(context, reg_LRA);
220 current_control_frame_pointer += 8;
221 /* Build our frame on top of it. */
222 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
225 /* We haven't yet called, build our frame as if the
226 * partial frame wasn't there. */
227 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
230 /* We can't tell whether we are still in the caller if it had to
231 * allocate a stack frame due to stack arguments. */
232 /* This observation provoked some past CMUCL maintainer to ask
233 * "Can anything strange happen during return?" */
236 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
239 current_control_stack_pointer = current_control_frame_pointer + 8;
241 current_control_frame_pointer[0] = oldcont;
242 current_control_frame_pointer[1] = NIL;
243 current_control_frame_pointer[2] =
244 (lispobj)(*os_context_register_addr(context, reg_CODE));
248 /* Stores the context for gc to scavange and builds fake stack
251 fake_foreign_function_call(os_context_t *context)
254 struct thread *thread=arch_os_get_current_thread();
256 /* context_index incrementing must not be interrupted */
257 check_blockables_blocked_or_lose();
259 /* Get current Lisp state from context. */
261 dynamic_space_free_pointer =
262 (lispobj *)(unsigned long)
263 (*os_context_register_addr(context, reg_ALLOC));
264 /* fprintf(stderr,"dynamic_space_free_pointer: %p\n", dynamic_space_free_pointer); */
265 #if defined(LISP_FEATURE_ALPHA)
266 if ((long)dynamic_space_free_pointer & 1) {
267 lose("dead in fake_foreign_function_call, context = %x\n", context);
272 current_binding_stack_pointer =
273 (lispobj *)(unsigned long)
274 (*os_context_register_addr(context, reg_BSP));
277 build_fake_control_stack_frames(thread,context);
279 /* Do dynamic binding of the active interrupt context index
280 * and save the context in the context array. */
282 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
284 if (context_index >= MAX_INTERRUPTS) {
285 lose("maximum interrupt nesting depth (%d) exceeded\n", MAX_INTERRUPTS);
288 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
289 make_fixnum(context_index + 1),thread);
291 thread->interrupt_contexts[context_index] = context;
293 /* no longer in Lisp now */
294 foreign_function_call_active = 1;
297 /* blocks all blockable signals. If you are calling from a signal handler,
298 * the usual signal mask will be restored from the context when the handler
299 * finishes. Otherwise, be careful */
301 undo_fake_foreign_function_call(os_context_t *context)
303 struct thread *thread=arch_os_get_current_thread();
304 /* Block all blockable signals. */
305 block_blockable_signals();
307 /* going back into Lisp */
308 foreign_function_call_active = 0;
310 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
314 /* Put the dynamic space free pointer back into the context. */
315 *os_context_register_addr(context, reg_ALLOC) =
316 (unsigned long) dynamic_space_free_pointer
317 | (*os_context_register_addr(context, reg_ALLOC)
320 ((unsigned long)(*os_context_register_addr(context, reg_ALLOC)) & ~LOWTAG_MASK)
321 | ((unsigned long) dynamic_space_free_pointer & LOWTAG_MASK);
326 /* a handler for the signal caused by execution of a trap opcode
327 * signalling an internal error */
329 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
334 fake_foreign_function_call(context);
336 if (!internal_errors_enabled) {
337 describe_internal_error(context);
338 /* There's no good way to recover from an internal error
339 * before the Lisp error handling mechanism is set up. */
340 lose("internal error too early in init, can't recover\n");
343 /* Allocate the SAP object while the interrupts are still
345 context_sap = alloc_sap(context);
347 #ifndef LISP_FEATURE_WIN32
348 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
351 SHOW("in interrupt_internal_error");
353 /* Display some rudimentary debugging information about the
354 * error, so that even if the Lisp error handler gets badly
355 * confused, we have a chance to determine what's going on. */
356 describe_internal_error(context);
358 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
359 continuable ? T : NIL);
361 undo_fake_foreign_function_call(context); /* blocks signals again */
363 arch_skip_instruction(context);
367 interrupt_handle_pending(os_context_t *context)
369 struct thread *thread;
370 struct interrupt_data *data;
372 FSHOW_SIGNAL((stderr, "/entering interrupt_handle_pending\n"));
374 check_blockables_blocked_or_lose();
375 thread=arch_os_get_current_thread();
376 data=thread->interrupt_data;
378 /* If pseudo_atomic_interrupted is set then the interrupt is going
379 * to be handled now, ergo it's safe to clear it. */
380 arch_clear_pseudo_atomic_interrupted(context);
382 if (SymbolValue(GC_INHIBIT,thread)==NIL) {
383 #ifdef LISP_FEATURE_SB_THREAD
384 if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
385 /* another thread has already initiated a gc, this attempt
386 * might as well be cancelled */
387 SetSymbolValue(GC_PENDING,NIL,thread);
388 SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
389 sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
392 if (SymbolValue(GC_PENDING,thread) != NIL) {
393 /* GC_PENDING is cleared in SUB-GC, or if another thread
394 * is doing a gc already we will get a SIG_STOP_FOR_GC and
395 * that will clear it. */
396 interrupt_maybe_gc_int(0,NULL,context);
398 check_blockables_blocked_or_lose();
401 /* we may be here only to do the gc stuff, if interrupts are
402 * enabled run the pending handler */
403 if (!((SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) ||
405 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
406 (!foreign_function_call_active) &&
408 arch_pseudo_atomic_atomic(context)))) {
410 /* There may be no pending handler, because it was only a gc
411 * that had to be executed or because pseudo atomic triggered
412 * twice for a single interrupt. For the interested reader,
413 * that may happen if an interrupt hits after the interrupted
414 * flag is cleared but before pseduo-atomic is set and a
415 * pseudo atomic is interrupted in that interrupt. */
416 if (data->pending_handler) {
418 /* If we're here as the result of a pseudo-atomic as opposed
419 * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
420 * NIL, because maybe_defer_handler sets
421 * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
422 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
424 #ifndef LISP_FEATURE_WIN32
425 /* restore the saved signal mask from the original signal (the
426 * one that interrupted us during the critical section) into the
427 * os_context for the signal we're currently in the handler for.
428 * This should ensure that when we return from the handler the
429 * blocked signals are unblocked */
430 sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
432 sigemptyset(&data->pending_mask);
434 /* This will break on sparc linux: the deferred handler really wants
435 * to be called with a void_context */
436 run_deferred_handler(data,(void *)context);
442 * the two main signal handlers:
443 * interrupt_handle_now(..)
444 * maybe_now_maybe_later(..)
446 * to which we have added interrupt_handle_now_handler(..). Why?
447 * Well, mostly because the SPARC/Linux platform doesn't quite do
448 * signals the way we want them done. The third argument in the
449 * handler isn't filled in by the kernel properly, so we fix it up
450 * ourselves in the arch_os_get_context(..) function; however, we only
451 * want to do this when we first hit the handler, and not when
452 * interrupt_handle_now(..) is being called from some other handler
453 * (when the fixup will already have been done). -- CSR, 2002-07-23
457 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
459 os_context_t *context = (os_context_t*)void_context;
460 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
461 boolean were_in_lisp;
463 union interrupt_handler handler;
465 check_blockables_blocked_or_lose();
468 #ifndef LISP_FEATURE_WIN32
469 if (sigismember(&deferrable_sigset,signal))
470 check_interrupts_enabled_or_lose(context);
473 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
474 /* Under Linux on some architectures, we appear to have to restore
475 the FPU control word from the context, as after the signal is
476 delivered we appear to have a null FPU control word. */
477 os_restore_fp_control(context);
481 handler = interrupt_handlers[signal];
483 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
487 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
488 were_in_lisp = !foreign_function_call_active;
492 fake_foreign_function_call(context);
495 FSHOW_SIGNAL((stderr,
496 "/entering interrupt_handle_now(%d, info, context)\n",
499 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
501 /* This can happen if someone tries to ignore or default one
502 * of the signals we need for runtime support, and the runtime
503 * support decides to pass on it. */
504 lose("no handler for signal %d in interrupt_handle_now(..)\n", signal);
506 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
507 /* Once we've decided what to do about contexts in a
508 * return-elsewhere world (the original context will no longer
509 * be available; should we copy it or was nobody using it anyway?)
510 * then we should convert this to return-elsewhere */
512 /* CMUCL comment said "Allocate the SAPs while the interrupts
513 * are still disabled.". I (dan, 2003.08.21) assume this is
514 * because we're not in pseudoatomic and allocation shouldn't
515 * be interrupted. In which case it's no longer an issue as
516 * all our allocation from C now goes through a PA wrapper,
517 * but still, doesn't hurt.
519 * Yeah, but non-gencgc platforms don't really wrap allocation
520 * in PA. MG - 2005-08-29 */
522 lispobj info_sap,context_sap = alloc_sap(context);
523 info_sap = alloc_sap(info);
524 /* Leave deferrable signals blocked, the handler itself will
525 * allow signals again when it sees fit. */
526 #ifdef LISP_FEATURE_SB_THREAD
529 sigemptyset(&unblock);
530 sigaddset(&unblock, SIG_STOP_FOR_GC);
531 #ifdef SIG_RESUME_FROM_GC
532 sigaddset(&unblock, SIG_RESUME_FROM_GC);
534 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
538 FSHOW_SIGNAL((stderr,"/calling Lisp-level handler\n"));
540 funcall3(handler.lisp,
546 FSHOW_SIGNAL((stderr,"/calling C-level handler\n"));
548 #ifndef LISP_FEATURE_WIN32
549 /* Allow signals again. */
550 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
553 (*handler.c)(signal, info, void_context);
556 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
560 undo_fake_foreign_function_call(context); /* block signals again */
563 FSHOW_SIGNAL((stderr,
564 "/returning from interrupt_handle_now(%d, info, context)\n",
568 /* This is called at the end of a critical section if the indications
569 * are that some signal was deferred during the section. Note that as
570 * far as C or the kernel is concerned we dealt with the signal
571 * already; we're just doing the Lisp-level processing now that we
574 run_deferred_handler(struct interrupt_data *data, void *v_context) {
575 /* The pending_handler may enable interrupts and then another
576 * interrupt may hit, overwrite interrupt_data, so reset the
577 * pending handler before calling it. Trust the handler to finish
578 * with the siginfo before enabling interrupts. */
579 void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
580 os_context_t *context = arch_os_get_context(&v_context);
582 data->pending_handler=0;
583 (*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
586 #ifndef LISP_FEATURE_WIN32
588 maybe_defer_handler(void *handler, struct interrupt_data *data,
589 int signal, siginfo_t *info, os_context_t *context)
591 struct thread *thread=arch_os_get_current_thread();
593 check_blockables_blocked_or_lose();
595 if (SymbolValue(INTERRUPT_PENDING,thread) != NIL)
596 lose("interrupt already pending\n");
597 /* If interrupts are disabled then INTERRUPT_PENDING is set and
598 * not PSEDUO_ATOMIC_INTERRUPTED. This is important for a pseudo
599 * atomic section inside a WITHOUT-INTERRUPTS.
601 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
602 store_signal_data_for_later(data,handler,signal,info,context);
603 SetSymbolValue(INTERRUPT_PENDING, T,thread);
604 FSHOW_SIGNAL((stderr,
605 "/maybe_defer_handler(%x,%d),thread=%lu: deferred\n",
606 (unsigned int)handler,signal,
607 (unsigned long)thread->os_thread));
610 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
611 * actually use its argument for anything on x86, so this branch
612 * may succeed even when context is null (gencgc alloc()) */
614 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
615 /* FIXME: this foreign_function_call_active test is dubious at
616 * best. If a foreign call is made in a pseudo atomic section
617 * (?) or more likely a pseudo atomic section is in a foreign
618 * call then an interrupt is executed immediately. Maybe it
619 * has to do with C code not maintaining pseudo atomic
620 * properly. MG - 2005-08-10 */
621 (!foreign_function_call_active) &&
623 arch_pseudo_atomic_atomic(context)) {
624 store_signal_data_for_later(data,handler,signal,info,context);
625 arch_set_pseudo_atomic_interrupted(context);
626 FSHOW_SIGNAL((stderr,
627 "/maybe_defer_handler(%x,%d),thread=%lu: deferred(PA)\n",
628 (unsigned int)handler,signal,
629 (unsigned long)thread->os_thread));
632 FSHOW_SIGNAL((stderr,
633 "/maybe_defer_handler(%x,%d),thread=%lu: not deferred\n",
634 (unsigned int)handler,signal,
635 (unsigned long)thread->os_thread));
640 store_signal_data_for_later (struct interrupt_data *data, void *handler,
642 siginfo_t *info, os_context_t *context)
644 if (data->pending_handler)
645 lose("tried to overwrite pending interrupt handler %x with %x\n",
646 data->pending_handler, handler);
648 lose("tried to defer null interrupt handler\n");
649 data->pending_handler = handler;
650 data->pending_signal = signal;
652 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
654 FSHOW_SIGNAL((stderr, "/store_signal_data_for_later: signal: %d\n", signal));
657 /* the signal mask in the context (from before we were
658 * interrupted) is copied to be restored when
659 * run_deferred_handler happens. Then the usually-blocked
660 * signals are added to the mask in the context so that we are
661 * running with blocked signals when the handler returns */
662 sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
663 sigaddset_deferrable(os_context_sigmask_addr(context));
668 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
670 os_context_t *context = arch_os_get_context(&void_context);
672 struct thread *thread;
673 struct interrupt_data *data;
675 thread=arch_os_get_current_thread();
676 data=thread->interrupt_data;
678 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
679 os_restore_fp_control(context);
682 if(maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
684 interrupt_handle_now(signal, info, context);
685 #ifdef LISP_FEATURE_DARWIN
686 /* Work around G5 bug */
687 DARWIN_FIX_CONTEXT(context);
692 low_level_interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
694 os_context_t *context = (os_context_t*)void_context;
696 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
697 os_restore_fp_control(context);
700 check_blockables_blocked_or_lose();
701 check_interrupts_enabled_or_lose(context);
702 interrupt_low_level_handlers[signal](signal, info, void_context);
703 #ifdef LISP_FEATURE_DARWIN
704 /* Work around G5 bug */
705 DARWIN_FIX_CONTEXT(context);
710 low_level_maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
712 os_context_t *context = arch_os_get_context(&void_context);
713 struct thread *thread;
714 struct interrupt_data *data;
716 thread=arch_os_get_current_thread();
717 data=thread->interrupt_data;
719 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
720 os_restore_fp_control(context);
723 if(maybe_defer_handler(low_level_interrupt_handle_now,data,
724 signal,info,context))
726 low_level_interrupt_handle_now(signal, info, context);
727 #ifdef LISP_FEATURE_DARWIN
728 /* Work around G5 bug */
729 DARWIN_FIX_CONTEXT(context);
734 #ifdef LISP_FEATURE_SB_THREAD
737 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
739 os_context_t *context = arch_os_get_context(&void_context);
741 struct thread *thread=arch_os_get_current_thread();
744 if ((arch_pseudo_atomic_atomic(context) ||
745 SymbolValue(GC_INHIBIT,thread) != NIL)) {
746 SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
747 if (SymbolValue(GC_INHIBIT,thread) == NIL)
748 arch_set_pseudo_atomic_interrupted(context);
749 FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred\n",
752 /* need the context stored so it can have registers scavenged */
753 fake_foreign_function_call(context);
755 sigfillset(&ss); /* Block everything. */
756 thread_sigmask(SIG_BLOCK,&ss,0);
758 if(thread->state!=STATE_RUNNING) {
759 lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
760 fixnum_value(thread->state));
762 thread->state=STATE_SUSPENDED;
763 FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
765 #if defined(SIG_RESUME_FROM_GC)
766 sigemptyset(&ss); sigaddset(&ss,SIG_RESUME_FROM_GC);
768 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
771 /* It is possible to get SIGCONT (and probably other
772 * non-blockable signals) here. */
773 #ifdef SIG_RESUME_FROM_GC
776 do { sigwait(&ss, &sigret); }
777 while (sigret != SIG_RESUME_FROM_GC);
780 while (sigwaitinfo(&ss,0) != SIG_STOP_FOR_GC);
783 FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
784 if(thread->state!=STATE_RUNNING) {
785 lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
786 fixnum_value(thread->state));
789 undo_fake_foreign_function_call(context);
795 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
797 os_context_t *context = arch_os_get_context(&void_context);
798 interrupt_handle_now(signal, info, context);
799 #ifdef LISP_FEATURE_DARWIN
800 DARWIN_FIX_CONTEXT(context);
805 * stuff to detect and handle hitting the GC trigger
808 #ifndef LISP_FEATURE_GENCGC
809 /* since GENCGC has its own way to record trigger */
811 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
813 if (current_auto_gc_trigger == NULL)
816 void *badaddr=arch_get_bad_addr(signal,info,context);
817 return (badaddr >= (void *)current_auto_gc_trigger &&
818 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
823 /* manipulate the signal context and stack such that when the handler
824 * returns, it will call function instead of whatever it was doing
828 #if (defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
829 extern int *context_eflags_addr(os_context_t *context);
832 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
833 extern void post_signal_tramp(void);
834 extern void call_into_lisp_tramp(void);
836 arrange_return_to_lisp_function(os_context_t *context, lispobj function)
838 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
839 void * fun=native_pointer(function);
840 void *code = &(((struct simple_fun *) fun)->code);
843 /* Build a stack frame showing `interrupted' so that the
844 * user's backtrace makes (as much) sense (as usual) */
846 /* FIXME: what about restoring fp state? */
847 /* FIXME: what about restoring errno? */
848 #ifdef LISP_FEATURE_X86
849 /* Suppose the existence of some function that saved all
850 * registers, called call_into_lisp, then restored GP registers and
851 * returned. It would look something like this:
859 pushl {address of function to call}
860 call 0x8058db0 <call_into_lisp>
867 * What we do here is set up the stack that call_into_lisp would
868 * expect to see if it had been called by this code, and frob the
869 * signal context so that signal return goes directly to call_into_lisp,
870 * and when that function (and the lisp function it invoked) returns,
871 * it returns to the second half of this imaginary function which
872 * restores all registers and returns to C
874 * For this to work, the latter part of the imaginary function
875 * must obviously exist in reality. That would be post_signal_tramp
878 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
880 #if defined(LISP_FEATURE_DARWIN)
881 u32 *register_save_area = (u32 *)os_validate(0, 0x40);
883 FSHOW_SIGNAL((stderr, "/arrange_return_to_lisp_function: preparing to go to function %x, sp: %x\n", function, sp));
884 FSHOW_SIGNAL((stderr, "/arrange_return_to_lisp_function: context: %x, &context %x\n", context, &context));
886 /* 1. os_validate (malloc/mmap) register_save_block
887 * 2. copy register state into register_save_block
888 * 3. put a pointer to register_save_block in a register in the context
889 * 4. set the context's EIP to point to a trampoline which:
890 * a. builds the fake stack frame from the block
892 * c. calls the function
895 *register_save_area = *os_context_pc_addr(context);
896 *(register_save_area + 1) = function;
897 *(register_save_area + 2) = *os_context_register_addr(context,reg_EDI);
898 *(register_save_area + 3) = *os_context_register_addr(context,reg_ESI);
899 *(register_save_area + 4) = *os_context_register_addr(context,reg_EDX);
900 *(register_save_area + 5) = *os_context_register_addr(context,reg_ECX);
901 *(register_save_area + 6) = *os_context_register_addr(context,reg_EBX);
902 *(register_save_area + 7) = *os_context_register_addr(context,reg_EAX);
903 *(register_save_area + 8) = *context_eflags_addr(context);
905 *os_context_pc_addr(context) = call_into_lisp_tramp;
906 *os_context_register_addr(context,reg_ECX) = register_save_area;
909 /* return address for call_into_lisp: */
910 *(sp-15) = (u32)post_signal_tramp;
911 *(sp-14) = function; /* args for call_into_lisp : function*/
912 *(sp-13) = 0; /* arg array */
913 *(sp-12) = 0; /* no. args */
914 /* this order matches that used in POPAD */
915 *(sp-11)=*os_context_register_addr(context,reg_EDI);
916 *(sp-10)=*os_context_register_addr(context,reg_ESI);
918 *(sp-9)=*os_context_register_addr(context,reg_ESP)-8;
919 /* POPAD ignores the value of ESP: */
921 *(sp-7)=*os_context_register_addr(context,reg_EBX);
923 *(sp-6)=*os_context_register_addr(context,reg_EDX);
924 *(sp-5)=*os_context_register_addr(context,reg_ECX);
925 *(sp-4)=*os_context_register_addr(context,reg_EAX);
926 *(sp-3)=*context_eflags_addr(context);
927 *(sp-2)=*os_context_register_addr(context,reg_EBP);
928 *(sp-1)=*os_context_pc_addr(context);
932 #elif defined(LISP_FEATURE_X86_64)
933 u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
934 /* return address for call_into_lisp: */
935 *(sp-18) = (u64)post_signal_tramp;
937 *(sp-17)=*os_context_register_addr(context,reg_R15);
938 *(sp-16)=*os_context_register_addr(context,reg_R14);
939 *(sp-15)=*os_context_register_addr(context,reg_R13);
940 *(sp-14)=*os_context_register_addr(context,reg_R12);
941 *(sp-13)=*os_context_register_addr(context,reg_R11);
942 *(sp-12)=*os_context_register_addr(context,reg_R10);
943 *(sp-11)=*os_context_register_addr(context,reg_R9);
944 *(sp-10)=*os_context_register_addr(context,reg_R8);
945 *(sp-9)=*os_context_register_addr(context,reg_RDI);
946 *(sp-8)=*os_context_register_addr(context,reg_RSI);
947 /* skip RBP and RSP */
948 *(sp-7)=*os_context_register_addr(context,reg_RBX);
949 *(sp-6)=*os_context_register_addr(context,reg_RDX);
950 *(sp-5)=*os_context_register_addr(context,reg_RCX);
951 *(sp-4)=*os_context_register_addr(context,reg_RAX);
952 *(sp-3)=*context_eflags_addr(context);
953 *(sp-2)=*os_context_register_addr(context,reg_RBP);
954 *(sp-1)=*os_context_pc_addr(context);
956 *os_context_register_addr(context,reg_RDI) =
957 (os_context_register_t)function; /* function */
958 *os_context_register_addr(context,reg_RSI) = 0; /* arg. array */
959 *os_context_register_addr(context,reg_RDX) = 0; /* no. args */
961 struct thread *th=arch_os_get_current_thread();
962 build_fake_control_stack_frames(th,context);
965 #ifdef LISP_FEATURE_X86
967 #if !defined(LISP_FEATURE_DARWIN)
968 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
969 *os_context_register_addr(context,reg_ECX) = 0;
970 *os_context_register_addr(context,reg_EBP) = (os_context_register_t)(sp-2);
972 *os_context_register_addr(context,reg_UESP) =
973 (os_context_register_t)(sp-15);
975 *os_context_register_addr(context,reg_ESP) = (os_context_register_t)(sp-15);
976 #endif /* __NETBSD__ */
977 #endif /* LISP_FEATURE_DARWIN */
979 #elif defined(LISP_FEATURE_X86_64)
980 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
981 *os_context_register_addr(context,reg_RCX) = 0;
982 *os_context_register_addr(context,reg_RBP) = (os_context_register_t)(sp-2);
983 *os_context_register_addr(context,reg_RSP) = (os_context_register_t)(sp-18);
985 /* this much of the calling convention is common to all
987 *os_context_pc_addr(context) = (os_context_register_t)(unsigned long)code;
988 *os_context_register_addr(context,reg_NARGS) = 0;
989 *os_context_register_addr(context,reg_LIP) =
990 (os_context_register_t)(unsigned long)code;
991 *os_context_register_addr(context,reg_CFP) =
992 (os_context_register_t)(unsigned long)current_control_frame_pointer;
994 #ifdef ARCH_HAS_NPC_REGISTER
995 *os_context_npc_addr(context) =
996 4 + *os_context_pc_addr(context);
998 #ifdef LISP_FEATURE_SPARC
999 *os_context_register_addr(context,reg_CODE) =
1000 (os_context_register_t)(fun + FUN_POINTER_LOWTAG);
1004 #ifdef LISP_FEATURE_SB_THREAD
1006 /* FIXME: this function can go away when all lisp handlers are invoked
1007 * via arrange_return_to_lisp_function. */
1009 interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
1011 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
1013 /* let the handler enable interrupts again when it sees fit */
1014 sigaddset_deferrable(os_context_sigmask_addr(context));
1015 arrange_return_to_lisp_function(context, SymbolFunction(RUN_INTERRUPTION));
1020 /* KLUDGE: Theoretically the approach we use for undefined alien
1021 * variables should work for functions as well, but on PPC/Darwin
1022 * we get bus error at bogus addresses instead, hence this workaround,
1023 * that has the added benefit of automatically discriminating between
1024 * functions and variables.
1027 undefined_alien_function() {
1028 funcall0(SymbolFunction(UNDEFINED_ALIEN_FUNCTION_ERROR));
1032 handle_guard_page_triggered(os_context_t *context,os_vm_address_t addr)
1034 struct thread *th=arch_os_get_current_thread();
1036 /* note the os_context hackery here. When the signal handler returns,
1037 * it won't go back to what it was doing ... */
1038 if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
1039 addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
1040 /* We hit the end of the control stack: disable guard page
1041 * protection so the error handler has some headroom, protect the
1042 * previous page so that we can catch returns from the guard page
1043 * and restore it. */
1044 protect_control_stack_guard_page(0);
1045 protect_control_stack_return_guard_page(1);
1047 arrange_return_to_lisp_function
1048 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
1051 else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
1052 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
1053 /* We're returning from the guard page: reprotect it, and
1054 * unprotect this one. This works even if we somehow missed
1055 * the return-guard-page, and hit it on our way to new
1056 * exhaustion instead. */
1057 protect_control_stack_guard_page(1);
1058 protect_control_stack_return_guard_page(0);
1061 else if (addr >= undefined_alien_address &&
1062 addr < undefined_alien_address + os_vm_page_size) {
1063 arrange_return_to_lisp_function
1064 (context, SymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
1070 #ifndef LISP_FEATURE_GENCGC
1071 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
1072 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
1073 * whether the signal was due to treading on the mprotect()ed zone -
1074 * and if so, arrange for a GC to happen. */
1075 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
1078 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
1080 os_context_t *context=(os_context_t *) void_context;
1082 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
1083 struct thread *thread=arch_os_get_current_thread();
1084 clear_auto_gc_trigger();
1085 /* Don't flood the system with interrupts if the need to gc is
1086 * already noted. This can happen for example when SUB-GC
1087 * allocates or after a gc triggered in a WITHOUT-GCING. */
1088 if (SymbolValue(GC_PENDING,thread) == NIL) {
1089 if (SymbolValue(GC_INHIBIT,thread) == NIL) {
1090 if (arch_pseudo_atomic_atomic(context)) {
1091 /* set things up so that GC happens when we finish
1093 SetSymbolValue(GC_PENDING,T,thread);
1094 arch_set_pseudo_atomic_interrupted(context);
1096 interrupt_maybe_gc_int(signal,info,void_context);
1099 SetSymbolValue(GC_PENDING,T,thread);
1109 /* this is also used by gencgc, in alloc() */
1111 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
1113 os_context_t *context=(os_context_t *) void_context;
1114 #ifndef LISP_FEATURE_WIN32
1115 struct thread *thread=arch_os_get_current_thread();
1118 fake_foreign_function_call(context);
1120 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
1121 * which case we will be running with no gc trigger barrier
1122 * thing for a while. But it shouldn't be long until the end
1125 * FIXME: It would be good to protect the end of dynamic space
1126 * and signal a storage condition from there.
1129 /* Restore the signal mask from the interrupted context before
1130 * calling into Lisp if interrupts are enabled. Why not always?
1132 * Suppose there is a WITHOUT-INTERRUPTS block far, far out. If an
1133 * interrupt hits while in SUB-GC, it is deferred and the
1134 * os_context_sigmask of that interrupt is set to block further
1135 * deferrable interrupts (until the first one is
1136 * handled). Unfortunately, that context refers to this place and
1137 * when we return from here the signals will not be blocked.
1139 * A kludgy alternative is to propagate the sigmask change to the
1142 #ifndef LISP_FEATURE_WIN32
1143 if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL)
1144 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
1145 #ifdef LISP_FEATURE_SB_THREAD
1149 #if defined(SIG_RESUME_FROM_GC)
1150 sigaddset(&new,SIG_RESUME_FROM_GC);
1152 sigaddset(&new,SIG_STOP_FOR_GC);
1153 thread_sigmask(SIG_UNBLOCK,&new,0);
1157 funcall0(SymbolFunction(SUB_GC));
1159 undo_fake_foreign_function_call(context);
1165 * noise to install handlers
1168 #ifndef LISP_FEATURE_WIN32
1169 /* In Linux 2.4 synchronous signals (sigtrap & co) can be delivered if
1170 * they are blocked, in Linux 2.6 the default handler is invoked
1171 * instead that usually coredumps. One might hastily think that adding
1172 * SA_NODEFER helps, but until ~2.6.13 if SA_NODEFER is specified then
1173 * the whole sa_mask is ignored and instead of not adding the signal
1174 * in question to the mask. That means if it's not blockable the
1175 * signal must be unblocked at the beginning of signal handlers.
1177 * It turns out that NetBSD's SA_NODEFER doesn't DTRT in a different
1178 * way: if SA_NODEFER is set and the signal is in sa_mask, the signal
1179 * will be unblocked in the sigmask during the signal handler. -- RMK
1182 static volatile int sigaction_nodefer_works = -1;
1184 #define SA_NODEFER_TEST_BLOCK_SIGNAL SIGABRT
1185 #define SA_NODEFER_TEST_KILL_SIGNAL SIGUSR1
1188 sigaction_nodefer_test_handler(int signal, siginfo_t *info, void *void_context)
1190 sigset_t empty, current;
1192 sigemptyset(&empty);
1193 sigprocmask(SIG_BLOCK, &empty, ¤t);
1194 /* There should be exactly two blocked signals: the two we added
1195 * to sa_mask when setting up the handler. NetBSD doesn't block
1196 * the signal we're handling when SA_NODEFER is set; Linux before
1197 * 2.6.13 or so also doesn't block the other signal when
1198 * SA_NODEFER is set. */
1199 for(i = 1; i < NSIG; i++)
1200 if (sigismember(¤t, i) !=
1201 (((i == SA_NODEFER_TEST_BLOCK_SIGNAL) || (i == signal)) ? 1 : 0)) {
1202 FSHOW_SIGNAL((stderr, "SA_NODEFER doesn't work, signal %d\n", i));
1203 sigaction_nodefer_works = 0;
1205 if (sigaction_nodefer_works == -1)
1206 sigaction_nodefer_works = 1;
1210 see_if_sigaction_nodefer_works()
1212 struct sigaction sa, old_sa;
1214 sa.sa_flags = SA_SIGINFO | SA_NODEFER;
1215 sa.sa_sigaction = sigaction_nodefer_test_handler;
1216 sigemptyset(&sa.sa_mask);
1217 sigaddset(&sa.sa_mask, SA_NODEFER_TEST_BLOCK_SIGNAL);
1218 sigaddset(&sa.sa_mask, SA_NODEFER_TEST_KILL_SIGNAL);
1219 sigaction(SA_NODEFER_TEST_KILL_SIGNAL, &sa, &old_sa);
1220 /* Make sure no signals are blocked. */
1223 sigemptyset(&empty);
1224 sigprocmask(SIG_SETMASK, &empty, 0);
1226 kill(getpid(), SA_NODEFER_TEST_KILL_SIGNAL);
1227 while (sigaction_nodefer_works == -1);
1228 sigaction(SA_NODEFER_TEST_KILL_SIGNAL, &old_sa, NULL);
1231 #undef SA_NODEFER_TEST_BLOCK_SIGNAL
1232 #undef SA_NODEFER_TEST_KILL_SIGNAL
1235 unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1239 sigemptyset(&unblock);
1240 sigaddset(&unblock, signal);
1241 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1242 interrupt_handle_now_handler(signal, info, void_context);
1246 low_level_unblock_me_trampoline(int signal, siginfo_t *info, void *void_context)
1250 sigemptyset(&unblock);
1251 sigaddset(&unblock, signal);
1252 thread_sigmask(SIG_UNBLOCK, &unblock, 0);
1253 (*interrupt_low_level_handlers[signal])(signal, info, void_context);
1257 undoably_install_low_level_interrupt_handler (int signal,
1262 struct sigaction sa;
1264 if (0 > signal || signal >= NSIG) {
1265 lose("bad signal number %d\n", signal);
1268 if (ARE_SAME_HANDLER(handler, SIG_DFL))
1269 sa.sa_sigaction = handler;
1270 else if (sigismember(&deferrable_sigset,signal))
1271 sa.sa_sigaction = low_level_maybe_now_maybe_later;
1272 /* The use of a trampoline appears to break the
1273 arch_os_get_context() workaround for SPARC/Linux. For now,
1274 don't use the trampoline (and so be vulnerable to the problems
1275 that SA_NODEFER is meant to solve. */
1276 #if !(defined(LISP_FEATURE_SPARC) && defined(LISP_FEATURE_LINUX))
1277 else if (!sigaction_nodefer_works &&
1278 !sigismember(&blockable_sigset, signal))
1279 sa.sa_sigaction = low_level_unblock_me_trampoline;
1282 sa.sa_sigaction = handler;
1284 sigcopyset(&sa.sa_mask, &blockable_sigset);
1285 sa.sa_flags = SA_SIGINFO | SA_RESTART
1286 | (sigaction_nodefer_works ? SA_NODEFER : 0);
1287 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
1288 if((signal==SIG_MEMORY_FAULT)
1289 #ifdef SIG_MEMORY_FAULT2
1290 || (signal==SIG_MEMORY_FAULT2)
1292 #ifdef SIG_INTERRUPT_THREAD
1293 || (signal==SIG_INTERRUPT_THREAD)
1296 sa.sa_flags |= SA_ONSTACK;
1299 sigaction(signal, &sa, NULL);
1300 interrupt_low_level_handlers[signal] =
1301 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
1305 /* This is called from Lisp. */
1307 install_handler(int signal, void handler(int, siginfo_t*, void*))
1309 #ifndef LISP_FEATURE_WIN32
1310 struct sigaction sa;
1312 union interrupt_handler oldhandler;
1314 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
1317 sigaddset(&new, signal);
1318 thread_sigmask(SIG_BLOCK, &new, &old);
1320 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%x\n",
1321 (unsigned int)interrupt_low_level_handlers[signal]));
1322 if (interrupt_low_level_handlers[signal]==0) {
1323 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
1324 ARE_SAME_HANDLER(handler, SIG_IGN))
1325 sa.sa_sigaction = handler;
1326 else if (sigismember(&deferrable_sigset, signal))
1327 sa.sa_sigaction = maybe_now_maybe_later;
1328 else if (!sigaction_nodefer_works &&
1329 !sigismember(&blockable_sigset, signal))
1330 sa.sa_sigaction = unblock_me_trampoline;
1332 sa.sa_sigaction = interrupt_handle_now_handler;
1334 sigcopyset(&sa.sa_mask, &blockable_sigset);
1335 sa.sa_flags = SA_SIGINFO | SA_RESTART |
1336 (sigaction_nodefer_works ? SA_NODEFER : 0);
1337 sigaction(signal, &sa, NULL);
1340 oldhandler = interrupt_handlers[signal];
1341 interrupt_handlers[signal].c = handler;
1343 thread_sigmask(SIG_SETMASK, &old, 0);
1345 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
1347 return (unsigned long)oldhandler.lisp;
1349 /* Probably-wrong Win32 hack */
1357 #ifndef LISP_FEATURE_WIN32
1359 SHOW("entering interrupt_init()");
1360 see_if_sigaction_nodefer_works();
1361 sigemptyset(&deferrable_sigset);
1362 sigemptyset(&blockable_sigset);
1363 sigaddset_deferrable(&deferrable_sigset);
1364 sigaddset_blockable(&blockable_sigset);
1366 /* Set up high level handler information. */
1367 for (i = 0; i < NSIG; i++) {
1368 interrupt_handlers[i].c =
1369 /* (The cast here blasts away the distinction between
1370 * SA_SIGACTION-style three-argument handlers and
1371 * signal(..)-style one-argument handlers, which is OK
1372 * because it works to call the 1-argument form where the
1373 * 3-argument form is expected.) */
1374 (void (*)(int, siginfo_t*, void*))SIG_DFL;
1377 SHOW("returning from interrupt_init()");