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>
55 #include "interrupt.h"
64 #include "genesis/fdefn.h"
65 #include "genesis/simple-fun.h"
69 void run_deferred_handler(struct interrupt_data *data, void *v_context) ;
70 static void store_signal_data_for_later (struct interrupt_data *data,
71 void *handler, int signal,
73 os_context_t *context);
74 boolean interrupt_maybe_gc_int(int signal, siginfo_t *info, void *v_context);
76 extern volatile lispobj all_threads_lock;
77 extern volatile int countdown_to_gc;
80 * This is a workaround for some slightly silly Linux/GNU Libc
81 * behaviour: glibc defines sigset_t to support 1024 signals, which is
82 * more than the kernel. This is usually not a problem, but becomes
83 * one when we want to save a signal mask from a ucontext, and restore
84 * it later into another ucontext: the ucontext is allocated on the
85 * stack by the kernel, so copying a libc-sized sigset_t into it will
86 * overflow and cause other data on the stack to be corrupted */
88 #define REAL_SIGSET_SIZE_BYTES ((NSIG/8))
90 void sigaddset_blockable(sigset_t *s)
94 sigaddset(s, SIGQUIT);
95 sigaddset(s, SIGPIPE);
96 sigaddset(s, SIGALRM);
99 sigaddset(s, SIGTSTP);
100 sigaddset(s, SIGCHLD);
102 sigaddset(s, SIGXCPU);
103 sigaddset(s, SIGXFSZ);
104 sigaddset(s, SIGVTALRM);
105 sigaddset(s, SIGPROF);
106 sigaddset(s, SIGWINCH);
107 sigaddset(s, SIGUSR1);
108 sigaddset(s, SIGUSR2);
109 #ifdef LISP_FEATURE_SB_THREAD
110 sigaddset(s, SIG_STOP_FOR_GC);
111 sigaddset(s, SIG_INTERRUPT_THREAD);
112 sigaddset(s, SIG_THREAD_EXIT);
116 /* When we catch an internal error, should we pass it back to Lisp to
117 * be handled in a high-level way? (Early in cold init, the answer is
118 * 'no', because Lisp is still too brain-dead to handle anything.
119 * After sufficient initialization has been completed, the answer
121 boolean internal_errors_enabled = 0;
123 struct interrupt_data * global_interrupt_data;
125 /* At the toplevel repl we routinely call this function. The signal
126 * mask ought to be clear anyway most of the time, but may be non-zero
127 * if we were interrupted e.g. while waiting for a queue. */
130 void reset_signal_mask ()
134 sigprocmask(SIG_SETMASK,&new,0);
137 void reset_signal_mask ()
143 sigprocmask(SIG_SETMASK,&new,&old);
144 for(i=1; i<NSIG; i++) {
145 if(sigismember(&old,i)) {
147 "Warning: signal %d is masked: this is unexpected\n",i);
152 fprintf(stderr,"If this version of SBCL is less than three months old, please report this.\nOtherwise, please try a newer version first\n. Reset signal mask.\n");
160 * utility routines used by various signal handlers
164 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
166 #ifndef LISP_FEATURE_X86
170 /* Build a fake stack frame or frames */
172 current_control_frame_pointer =
173 (lispobj *)(*os_context_register_addr(context, reg_CSP));
174 if ((lispobj *)(*os_context_register_addr(context, reg_CFP))
175 == current_control_frame_pointer) {
176 /* There is a small window during call where the callee's
177 * frame isn't built yet. */
178 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
179 == FUN_POINTER_LOWTAG) {
180 /* We have called, but not built the new frame, so
181 * build it for them. */
182 current_control_frame_pointer[0] =
183 *os_context_register_addr(context, reg_OCFP);
184 current_control_frame_pointer[1] =
185 *os_context_register_addr(context, reg_LRA);
186 current_control_frame_pointer += 8;
187 /* Build our frame on top of it. */
188 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
191 /* We haven't yet called, build our frame as if the
192 * partial frame wasn't there. */
193 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
196 /* We can't tell whether we are still in the caller if it had to
197 * allocate a stack frame due to stack arguments. */
198 /* This observation provoked some past CMUCL maintainer to ask
199 * "Can anything strange happen during return?" */
202 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
205 current_control_stack_pointer = current_control_frame_pointer + 8;
207 current_control_frame_pointer[0] = oldcont;
208 current_control_frame_pointer[1] = NIL;
209 current_control_frame_pointer[2] =
210 (lispobj)(*os_context_register_addr(context, reg_CODE));
215 fake_foreign_function_call(os_context_t *context)
218 struct thread *thread=arch_os_get_current_thread();
220 /* Get current Lisp state from context. */
222 dynamic_space_free_pointer =
223 (lispobj *)(*os_context_register_addr(context, reg_ALLOC));
225 if ((long)dynamic_space_free_pointer & 1) {
226 lose("dead in fake_foreign_function_call, context = %x", context);
231 current_binding_stack_pointer =
232 (lispobj *)(*os_context_register_addr(context, reg_BSP));
235 build_fake_control_stack_frames(thread,context);
237 /* Do dynamic binding of the active interrupt context index
238 * and save the context in the context array. */
240 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
242 if (context_index >= MAX_INTERRUPTS) {
243 lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS);
246 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
247 make_fixnum(context_index + 1),thread);
249 thread->interrupt_contexts[context_index] = context;
251 /* no longer in Lisp now */
252 foreign_function_call_active = 1;
255 /* blocks all blockable signals. If you are calling from a signal handler,
256 * the usual signal mask will be restored from the context when the handler
257 * finishes. Otherwise, be careful */
260 undo_fake_foreign_function_call(os_context_t *context)
262 struct thread *thread=arch_os_get_current_thread();
263 /* Block all blockable signals. */
266 sigaddset_blockable(&block);
267 sigprocmask(SIG_BLOCK, &block, 0);
269 /* going back into Lisp */
270 foreign_function_call_active = 0;
272 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
276 /* Put the dynamic space free pointer back into the context. */
277 *os_context_register_addr(context, reg_ALLOC) =
278 (unsigned long) dynamic_space_free_pointer;
282 /* a handler for the signal caused by execution of a trap opcode
283 * signalling an internal error */
285 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
288 lispobj context_sap = 0;
290 fake_foreign_function_call(context);
292 /* Allocate the SAP object while the interrupts are still
294 if (internal_errors_enabled) {
295 context_sap = alloc_sap(context);
298 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
300 if (internal_errors_enabled) {
301 SHOW("in interrupt_internal_error");
303 /* Display some rudimentary debugging information about the
304 * error, so that even if the Lisp error handler gets badly
305 * confused, we have a chance to determine what's going on. */
306 describe_internal_error(context);
308 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
309 continuable ? T : NIL);
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");
316 undo_fake_foreign_function_call(context); /* blocks signals again */
318 arch_skip_instruction(context);
323 interrupt_handle_pending(os_context_t *context)
325 struct thread *thread;
326 struct interrupt_data *data;
328 thread=arch_os_get_current_thread();
329 data=thread->interrupt_data;
330 /* FIXME I'm not altogether sure this is appropriate if we're
331 * here as the result of a pseudo-atomic */
332 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
334 /* restore the saved signal mask from the original signal (the
335 * one that interrupted us during the critical section) into the
336 * os_context for the signal we're currently in the handler for.
337 * This should ensure that when we return from the handler the
338 * blocked signals are unblocked */
340 memcpy(os_context_sigmask_addr(context), &data->pending_mask,
341 REAL_SIGSET_SIZE_BYTES);
343 sigemptyset(&data->pending_mask);
344 /* This will break on sparc linux: the deferred handler really wants
345 * to be called with a void_context */
346 run_deferred_handler(data,(void *)context);
350 * the two main signal handlers:
351 * interrupt_handle_now(..)
352 * maybe_now_maybe_later(..)
354 * to which we have added interrupt_handle_now_handler(..). Why?
355 * Well, mostly because the SPARC/Linux platform doesn't quite do
356 * signals the way we want them done. The third argument in the
357 * handler isn't filled in by the kernel properly, so we fix it up
358 * ourselves in the arch_os_get_context(..) function; however, we only
359 * want to do this when we first hit the handler, and not when
360 * interrupt_handle_now(..) is being called from some other handler
361 * (when the fixup will already have been done). -- CSR, 2002-07-23
365 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
367 os_context_t *context = (os_context_t*)void_context;
368 struct thread *thread=arch_os_get_current_thread();
369 #ifndef LISP_FEATURE_X86
370 boolean were_in_lisp;
372 union interrupt_handler handler;
374 #ifdef LISP_FEATURE_LINUX
375 /* Under Linux on some architectures, we appear to have to restore
376 the FPU control word from the context, as after the signal is
377 delivered we appear to have a null FPU control word. */
378 os_restore_fp_control(context);
380 handler = thread->interrupt_data->interrupt_handlers[signal];
382 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
386 #ifndef LISP_FEATURE_X86
387 were_in_lisp = !foreign_function_call_active;
391 fake_foreign_function_call(context);
396 "/entering interrupt_handle_now(%d, info, context)\n",
400 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
402 /* This can happen if someone tries to ignore or default one
403 * of the signals we need for runtime support, and the runtime
404 * support decides to pass on it. */
405 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
407 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
408 /* Once we've decided what to do about contexts in a
409 * return-elsewhere world (the original context will no longer
410 * be available; should we copy it or was nobody using it anyway?)
411 * then we should convert this to return-elsewhere */
413 /* CMUCL comment said "Allocate the SAPs while the interrupts
414 * are still disabled.". I (dan, 2003.08.21) assume this is
415 * because we're not in pseudoatomic and allocation shouldn't
416 * be interrupted. In which case it's no longer an issue as
417 * all our allocation from C now goes through a PA wrapper,
418 * but still, doesn't hurt */
420 lispobj info_sap,context_sap = alloc_sap(context);
421 info_sap = alloc_sap(info);
422 /* Allow signals again. */
423 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
426 SHOW("calling Lisp-level handler");
429 funcall3(handler.lisp,
436 SHOW("calling C-level handler");
439 /* Allow signals again. */
440 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
442 (*handler.c)(signal, info, void_context);
445 #ifndef LISP_FEATURE_X86
449 undo_fake_foreign_function_call(context); /* block signals again */
454 "/returning from interrupt_handle_now(%d, info, context)\n",
459 /* This is called at the end of a critical section if the indications
460 * are that some signal was deferred during the section. Note that as
461 * far as C or the kernel is concerned we dealt with the signal
462 * already; we're just doing the Lisp-level processing now that we
466 run_deferred_handler(struct interrupt_data *data, void *v_context) {
467 (*(data->pending_handler))
468 (data->pending_signal,&(data->pending_info), v_context);
469 data->pending_handler=0;
473 maybe_defer_handler(void *handler, struct interrupt_data *data,
474 int signal, siginfo_t *info, os_context_t *context)
476 struct thread *thread=arch_os_get_current_thread();
477 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
478 store_signal_data_for_later(data,handler,signal,info,context);
479 SetSymbolValue(INTERRUPT_PENDING, T,thread);
482 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
483 * actually use its argument for anything on x86, so this branch
484 * may succeed even when context is null (gencgc alloc()) */
486 #ifndef LISP_FEATURE_X86
487 (!foreign_function_call_active) &&
489 arch_pseudo_atomic_atomic(context)) {
490 store_signal_data_for_later(data,handler,signal,info,context);
491 arch_set_pseudo_atomic_interrupted(context);
497 store_signal_data_for_later (struct interrupt_data *data, void *handler,
499 siginfo_t *info, os_context_t *context)
501 data->pending_handler = handler;
502 data->pending_signal = signal;
504 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
506 /* the signal mask in the context (from before we were
507 * interrupted) is copied to be restored when
508 * run_deferred_handler happens. Then the usually-blocked
509 * signals are added to the mask in the context so that we are
510 * running with blocked signals when the handler returns */
511 sigemptyset(&(data->pending_mask));
512 memcpy(&(data->pending_mask),
513 os_context_sigmask_addr(context),
514 REAL_SIGSET_SIZE_BYTES);
515 sigaddset_blockable(os_context_sigmask_addr(context));
517 /* this is also called from gencgc alloc(), in which case
518 * there has been no signal and is therefore no context. */
521 sigaddset_blockable(&new);
522 sigprocmask(SIG_BLOCK,&new,&(data->pending_mask));
528 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
530 os_context_t *context = arch_os_get_context(&void_context);
531 struct thread *thread=arch_os_get_current_thread();
532 struct interrupt_data *data=thread->interrupt_data;
533 #ifdef LISP_FEATURE_LINUX
534 os_restore_fp_control(context);
536 if(maybe_defer_handler(interrupt_handle_now,data,
537 signal,info,context))
539 interrupt_handle_now(signal, info, context);
543 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
545 os_context_t *context = arch_os_get_context(&void_context);
546 struct thread *thread=arch_os_get_current_thread();
547 struct interrupt_data *data=thread->interrupt_data;
550 if(maybe_defer_handler(sig_stop_for_gc_handler,data,
551 signal,info,context)){
554 /* need the context stored so it can have registers scavenged */
555 fake_foreign_function_call(context);
557 get_spinlock(&all_threads_lock,thread->pid);
559 thread->state=STATE_STOPPED;
560 release_spinlock(&all_threads_lock);
561 kill(thread->pid,SIGSTOP);
563 undo_fake_foreign_function_call(context);
567 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
569 os_context_t *context = arch_os_get_context(&void_context);
570 interrupt_handle_now(signal, info, context);
574 * stuff to detect and handle hitting the GC trigger
577 #ifndef LISP_FEATURE_GENCGC
578 /* since GENCGC has its own way to record trigger */
580 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
582 if (current_auto_gc_trigger == NULL)
585 void *badaddr=arch_get_bad_addr(signal,info,context);
586 return (badaddr >= (void *)current_auto_gc_trigger &&
587 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
592 /* manipulate the signal context and stack such that when the handler
593 * returns, it will call function instead of whatever it was doing
597 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
598 extern void post_signal_tramp(void);
599 void arrange_return_to_lisp_function(os_context_t *context, lispobj function)
601 void * fun=native_pointer(function);
602 char *code = &(((struct simple_fun *) fun)->code);
604 /* Build a stack frame showing `interrupted' so that the
605 * user's backtrace makes (as much) sense (as usual) */
606 #ifdef LISP_FEATURE_X86
607 /* Suppose the existence of some function that saved all
608 * registers, called call_into_lisp, then restored GP registers and
609 * returned. We shortcut this: fake the stack that call_into_lisp
610 * would see, then arrange to have it called directly. post_signal_tramp
611 * is the second half of this function
613 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
615 *(sp-14) = post_signal_tramp; /* return address for call_into_lisp */
616 *(sp-13) = function; /* args for call_into_lisp : function*/
617 *(sp-12) = 0; /* arg array */
618 *(sp-11) = 0; /* no. args */
619 /* this order matches that used in POPAD */
620 *(sp-10)=*os_context_register_addr(context,reg_EDI);
621 *(sp-9)=*os_context_register_addr(context,reg_ESI);
622 /* this gets overwritten again before it's used, anyway */
623 *(sp-8)=*os_context_register_addr(context,reg_EBP);
624 *(sp-7)=0 ; /* POPAD doesn't set ESP, but expects a gap for it anyway */
625 *(sp-6)=*os_context_register_addr(context,reg_EBX);
627 *(sp-5)=*os_context_register_addr(context,reg_EDX);
628 *(sp-4)=*os_context_register_addr(context,reg_ECX);
629 *(sp-3)=*os_context_register_addr(context,reg_EAX);
630 *(sp-2)=*os_context_register_addr(context,reg_EBP);
631 *(sp-1)=*os_context_pc_addr(context);
634 struct thread *th=arch_os_get_current_thread();
635 build_fake_control_stack_frames(th,context);
638 #ifdef LISP_FEATURE_X86
639 *os_context_pc_addr(context) = call_into_lisp;
640 *os_context_register_addr(context,reg_ECX) = 0;
641 *os_context_register_addr(context,reg_EBP) = sp-2;
642 *os_context_register_addr(context,reg_ESP) = sp-14;
644 /* this much of the calling convention is common to all
646 *os_context_pc_addr(context) = code;
647 *os_context_register_addr(context,reg_NARGS) = 0;
648 *os_context_register_addr(context,reg_LIP) = code;
649 *os_context_register_addr(context,reg_CFP) =
650 current_control_frame_pointer;
652 #ifdef ARCH_HAS_NPC_REGISTER
653 *os_context_npc_addr(context) =
654 4 + *os_context_pc_addr(context);
656 #ifdef LISP_FEATURE_SPARC
657 *os_context_register_addr(context,reg_CODE) =
658 fun + FUN_POINTER_LOWTAG;
662 #ifdef LISP_FEATURE_SB_THREAD
663 void interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
665 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
666 struct thread *th=arch_os_get_current_thread();
667 struct interrupt_data *data=
668 th ? th->interrupt_data : global_interrupt_data;
669 if(maybe_defer_handler(interrupt_thread_handler,data,num,info,context)){
672 arrange_return_to_lisp_function(context,info->si_value.sival_int);
675 void thread_exit_handler(int num, siginfo_t *info, void *v_context)
676 { /* called when a child thread exits */
677 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
678 struct thread *th=arch_os_get_current_thread();
681 struct interrupt_data *data=
682 th ? th->interrupt_data : global_interrupt_data;
683 if(maybe_defer_handler(thread_exit_handler,data,num,info,context)){
687 kid=waitpid(-1,&status,__WALL|WNOHANG);
689 if(WIFEXITED(status) || WIFSIGNALED(status)) {
690 struct thread *th=find_thread_by_pid(kid);
692 funcall1(SymbolFunction(HANDLE_THREAD_EXIT),make_fixnum(kid));
699 boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr){
700 struct thread *th=arch_os_get_current_thread();
701 /* note the os_context hackery here. When the signal handler returns,
702 * it won't go back to what it was doing ... */
703 if(addr>=(void *)CONTROL_STACK_GUARD_PAGE(th) &&
704 addr<(void *)(CONTROL_STACK_GUARD_PAGE(th)+os_vm_page_size)) {
705 /* we hit the end of the control stack. disable protection
706 * temporarily so the error handler has some headroom */
707 protect_control_stack_guard_page(th->pid,0L);
709 arrange_return_to_lisp_function
710 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
716 #ifndef LISP_FEATURE_GENCGC
717 /* This function gets called from the SIGSEGV (for e.g. Linux or
718 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
719 * whether the signal was due to treading on the mprotect()ed zone -
720 * and if so, arrange for a GC to happen. */
721 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
724 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
726 os_context_t *context=(os_context_t *) void_context;
727 struct thread *th=arch_os_get_current_thread();
728 struct interrupt_data *data=
729 th ? th->interrupt_data : global_interrupt_data;
731 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
732 clear_auto_gc_trigger();
733 if(!maybe_defer_handler
734 (interrupt_maybe_gc_int,data,signal,info,void_context))
735 interrupt_maybe_gc_int(signal,info,void_context);
743 /* this is also used by gencgc, in alloc() */
745 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
748 os_context_t *context=(os_context_t *) void_context;
749 fake_foreign_function_call(context);
750 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
751 * which case we will be running with no gc trigger barrier
752 * thing for a while. But it shouldn't be long until the end
753 * of WITHOUT-GCING. */
756 sigaddset_blockable(&new);
757 /* enable signals before calling into Lisp */
758 sigprocmask(SIG_UNBLOCK,&new,0);
759 funcall0(SymbolFunction(SUB_GC));
760 undo_fake_foreign_function_call(context);
766 * noise to install handlers
770 undoably_install_low_level_interrupt_handler (int signal,
776 struct thread *th=arch_os_get_current_thread();
777 struct interrupt_data *data=
778 th ? th->interrupt_data : global_interrupt_data;
780 if (0 > signal || signal >= NSIG) {
781 lose("bad signal number %d", signal);
784 sa.sa_sigaction = handler;
785 sigemptyset(&sa.sa_mask);
786 sigaddset_blockable(&sa.sa_mask);
787 sa.sa_flags = SA_SIGINFO | SA_RESTART;
788 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
789 if((signal==SIG_MEMORY_FAULT)
790 #ifdef SIG_INTERRUPT_THREAD
791 || (signal==SIG_INTERRUPT_THREAD)
794 sa.sa_flags|= SA_ONSTACK;
797 sigaction(signal, &sa, NULL);
798 data->interrupt_low_level_handlers[signal] =
799 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
802 /* This is called from Lisp. */
804 install_handler(int signal, void handler(int, siginfo_t*, void*))
808 union interrupt_handler oldhandler;
809 struct thread *th=arch_os_get_current_thread();
810 struct interrupt_data *data=
811 th ? th->interrupt_data : global_interrupt_data;
813 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
816 sigaddset(&new, signal);
817 sigprocmask(SIG_BLOCK, &new, &old);
820 sigaddset_blockable(&new);
822 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%d\n",
823 interrupt_low_level_handlers[signal]));
824 if (data->interrupt_low_level_handlers[signal]==0) {
825 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
826 ARE_SAME_HANDLER(handler, SIG_IGN)) {
827 sa.sa_sigaction = handler;
828 } else if (sigismember(&new, signal)) {
829 sa.sa_sigaction = maybe_now_maybe_later;
831 sa.sa_sigaction = interrupt_handle_now_handler;
834 sigemptyset(&sa.sa_mask);
835 sigaddset_blockable(&sa.sa_mask);
836 sa.sa_flags = SA_SIGINFO | SA_RESTART;
837 sigaction(signal, &sa, NULL);
840 oldhandler = data->interrupt_handlers[signal];
841 data->interrupt_handlers[signal].c = handler;
843 sigprocmask(SIG_SETMASK, &old, 0);
845 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
847 return (unsigned long)oldhandler.lisp;
854 SHOW("entering interrupt_init()");
855 global_interrupt_data=calloc(sizeof(struct interrupt_data), 1);
857 /* Set up high level handler information. */
858 for (i = 0; i < NSIG; i++) {
859 global_interrupt_data->interrupt_handlers[i].c =
860 /* (The cast here blasts away the distinction between
861 * SA_SIGACTION-style three-argument handlers and
862 * signal(..)-style one-argument handlers, which is OK
863 * because it works to call the 1-argument form where the
864 * 3-argument form is expected.) */
865 (void (*)(int, siginfo_t*, void*))SIG_DFL;
868 SHOW("returning from interrupt_init()");