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;
79 * This is a workaround for some slightly silly Linux/GNU Libc
80 * behaviour: glibc defines sigset_t to support 1024 signals, which is
81 * more than the kernel. This is usually not a problem, but becomes
82 * one when we want to save a signal mask from a ucontext, and restore
83 * it later into another ucontext: the ucontext is allocated on the
84 * stack by the kernel, so copying a libc-sized sigset_t into it will
85 * overflow and cause other data on the stack to be corrupted */
87 #define REAL_SIGSET_SIZE_BYTES ((NSIG/8))
89 void sigaddset_blockable(sigset_t *s)
93 sigaddset(s, SIGQUIT);
94 sigaddset(s, SIGPIPE);
95 sigaddset(s, SIGALRM);
98 sigaddset(s, SIGTSTP);
99 sigaddset(s, SIGCHLD);
101 sigaddset(s, SIGXCPU);
102 sigaddset(s, SIGXFSZ);
103 sigaddset(s, SIGVTALRM);
104 sigaddset(s, SIGPROF);
105 sigaddset(s, SIGWINCH);
106 sigaddset(s, SIGUSR1);
107 sigaddset(s, SIGUSR2);
108 #ifdef LISP_FEATURE_SB_THREAD
109 sigaddset(s, SIG_STOP_FOR_GC);
110 sigaddset(s, SIG_INTERRUPT_THREAD);
114 /* When we catch an internal error, should we pass it back to Lisp to
115 * be handled in a high-level way? (Early in cold init, the answer is
116 * 'no', because Lisp is still too brain-dead to handle anything.
117 * After sufficient initialization has been completed, the answer
119 boolean internal_errors_enabled = 0;
121 struct interrupt_data * global_interrupt_data;
123 /* At the toplevel repl we routinely call this function. The signal
124 * mask ought to be clear anyway most of the time, but may be non-zero
125 * if we were interrupted e.g. while waiting for a queue. */
128 void reset_signal_mask ()
132 sigprocmask(SIG_SETMASK,&new,0);
135 void reset_signal_mask ()
141 sigprocmask(SIG_SETMASK,&new,&old);
142 for(i=1; i<NSIG; i++) {
143 if(sigismember(&old,i)) {
145 "Warning: signal %d is masked: this is unexpected\n",i);
150 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");
158 * utility routines used by various signal handlers
162 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
164 #ifndef LISP_FEATURE_X86
168 /* Build a fake stack frame or frames */
170 current_control_frame_pointer =
171 (lispobj *)(*os_context_register_addr(context, reg_CSP));
172 if ((lispobj *)(*os_context_register_addr(context, reg_CFP))
173 == current_control_frame_pointer) {
174 /* There is a small window during call where the callee's
175 * frame isn't built yet. */
176 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
177 == FUN_POINTER_LOWTAG) {
178 /* We have called, but not built the new frame, so
179 * build it for them. */
180 current_control_frame_pointer[0] =
181 *os_context_register_addr(context, reg_OCFP);
182 current_control_frame_pointer[1] =
183 *os_context_register_addr(context, reg_LRA);
184 current_control_frame_pointer += 8;
185 /* Build our frame on top of it. */
186 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
189 /* We haven't yet called, build our frame as if the
190 * partial frame wasn't there. */
191 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
194 /* We can't tell whether we are still in the caller if it had to
195 * allocate a stack frame due to stack arguments. */
196 /* This observation provoked some past CMUCL maintainer to ask
197 * "Can anything strange happen during return?" */
200 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
203 current_control_stack_pointer = current_control_frame_pointer + 8;
205 current_control_frame_pointer[0] = oldcont;
206 current_control_frame_pointer[1] = NIL;
207 current_control_frame_pointer[2] =
208 (lispobj)(*os_context_register_addr(context, reg_CODE));
213 fake_foreign_function_call(os_context_t *context)
216 struct thread *thread=arch_os_get_current_thread();
218 /* Get current Lisp state from context. */
220 dynamic_space_free_pointer =
221 (lispobj *)(*os_context_register_addr(context, reg_ALLOC));
223 if ((long)dynamic_space_free_pointer & 1) {
224 lose("dead in fake_foreign_function_call, context = %x", context);
229 current_binding_stack_pointer =
230 (lispobj *)(*os_context_register_addr(context, reg_BSP));
233 build_fake_control_stack_frames(thread,context);
235 /* Do dynamic binding of the active interrupt context index
236 * and save the context in the context array. */
238 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
240 if (context_index >= MAX_INTERRUPTS) {
241 lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS);
244 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
245 make_fixnum(context_index + 1),thread);
247 thread->interrupt_contexts[context_index] = context;
249 /* no longer in Lisp now */
250 foreign_function_call_active = 1;
253 /* blocks all blockable signals. If you are calling from a signal handler,
254 * the usual signal mask will be restored from the context when the handler
255 * finishes. Otherwise, be careful */
258 undo_fake_foreign_function_call(os_context_t *context)
260 struct thread *thread=arch_os_get_current_thread();
261 /* Block all blockable signals. */
264 sigaddset_blockable(&block);
265 sigprocmask(SIG_BLOCK, &block, 0);
267 /* going back into Lisp */
268 foreign_function_call_active = 0;
270 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
274 /* Put the dynamic space free pointer back into the context. */
275 *os_context_register_addr(context, reg_ALLOC) =
276 (unsigned long) dynamic_space_free_pointer;
280 /* a handler for the signal caused by execution of a trap opcode
281 * signalling an internal error */
283 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
286 lispobj context_sap = 0;
288 fake_foreign_function_call(context);
290 /* Allocate the SAP object while the interrupts are still
292 if (internal_errors_enabled) {
293 context_sap = alloc_sap(context);
296 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
298 if (internal_errors_enabled) {
299 SHOW("in interrupt_internal_error");
301 /* Display some rudimentary debugging information about the
302 * error, so that even if the Lisp error handler gets badly
303 * confused, we have a chance to determine what's going on. */
304 describe_internal_error(context);
306 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
307 continuable ? T : NIL);
309 describe_internal_error(context);
310 /* There's no good way to recover from an internal error
311 * before the Lisp error handling mechanism is set up. */
312 lose("internal error too early in init, can't recover");
314 undo_fake_foreign_function_call(context); /* blocks signals again */
316 arch_skip_instruction(context);
321 interrupt_handle_pending(os_context_t *context)
323 struct thread *thread;
324 struct interrupt_data *data;
326 thread=arch_os_get_current_thread();
327 data=thread->interrupt_data;
328 /* FIXME I'm not altogether sure this is appropriate if we're
329 * here as the result of a pseudo-atomic */
330 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
332 /* restore the saved signal mask from the original signal (the
333 * one that interrupted us during the critical section) into the
334 * os_context for the signal we're currently in the handler for.
335 * This should ensure that when we return from the handler the
336 * blocked signals are unblocked */
338 memcpy(os_context_sigmask_addr(context), &data->pending_mask,
339 REAL_SIGSET_SIZE_BYTES);
341 sigemptyset(&data->pending_mask);
342 /* This will break on sparc linux: the deferred handler really wants
343 * to be called with a void_context */
344 run_deferred_handler(data,(void *)context);
348 * the two main signal handlers:
349 * interrupt_handle_now(..)
350 * maybe_now_maybe_later(..)
352 * to which we have added interrupt_handle_now_handler(..). Why?
353 * Well, mostly because the SPARC/Linux platform doesn't quite do
354 * signals the way we want them done. The third argument in the
355 * handler isn't filled in by the kernel properly, so we fix it up
356 * ourselves in the arch_os_get_context(..) function; however, we only
357 * want to do this when we first hit the handler, and not when
358 * interrupt_handle_now(..) is being called from some other handler
359 * (when the fixup will already have been done). -- CSR, 2002-07-23
363 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
365 os_context_t *context = (os_context_t*)void_context;
366 struct thread *thread=arch_os_get_current_thread();
367 #ifndef LISP_FEATURE_X86
368 boolean were_in_lisp;
370 union interrupt_handler handler;
372 #ifdef LISP_FEATURE_LINUX
373 /* Under Linux on some architectures, we appear to have to restore
374 the FPU control word from the context, as after the signal is
375 delivered we appear to have a null FPU control word. */
376 os_restore_fp_control(context);
378 handler = thread->interrupt_data->interrupt_handlers[signal];
380 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
384 #ifndef LISP_FEATURE_X86
385 were_in_lisp = !foreign_function_call_active;
389 fake_foreign_function_call(context);
394 "/entering interrupt_handle_now(%d, info, context)\n",
398 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
400 /* This can happen if someone tries to ignore or default one
401 * of the signals we need for runtime support, and the runtime
402 * support decides to pass on it. */
403 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
405 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
406 /* Once we've decided what to do about contexts in a
407 * return-elsewhere world (the original context will no longer
408 * be available; should we copy it or was nobody using it anyway?)
409 * then we should convert this to return-elsewhere */
411 /* CMUCL comment said "Allocate the SAPs while the interrupts
412 * are still disabled.". I (dan, 2003.08.21) assume this is
413 * because we're not in pseudoatomic and allocation shouldn't
414 * be interrupted. In which case it's no longer an issue as
415 * all our allocation from C now goes through a PA wrapper,
416 * but still, doesn't hurt */
418 lispobj info_sap,context_sap = alloc_sap(context);
419 info_sap = alloc_sap(info);
420 /* Allow signals again. */
421 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
424 SHOW("calling Lisp-level handler");
427 funcall3(handler.lisp,
434 SHOW("calling C-level handler");
437 /* Allow signals again. */
438 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
440 (*handler.c)(signal, info, void_context);
443 #ifndef LISP_FEATURE_X86
447 undo_fake_foreign_function_call(context); /* block signals again */
452 "/returning from interrupt_handle_now(%d, info, context)\n",
457 /* This is called at the end of a critical section if the indications
458 * are that some signal was deferred during the section. Note that as
459 * far as C or the kernel is concerned we dealt with the signal
460 * already; we're just doing the Lisp-level processing now that we
464 run_deferred_handler(struct interrupt_data *data, void *v_context) {
465 (*(data->pending_handler))
466 (data->pending_signal,&(data->pending_info), v_context);
467 data->pending_handler=0;
471 maybe_defer_handler(void *handler, struct interrupt_data *data,
472 int signal, siginfo_t *info, os_context_t *context)
474 struct thread *thread=arch_os_get_current_thread();
475 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
476 store_signal_data_for_later(data,handler,signal,info,context);
477 SetSymbolValue(INTERRUPT_PENDING, T,thread);
480 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
481 * actually use its argument for anything on x86, so this branch
482 * may succeed even when context is null (gencgc alloc()) */
484 #ifndef LISP_FEATURE_X86
485 (!foreign_function_call_active) &&
487 arch_pseudo_atomic_atomic(context)) {
488 store_signal_data_for_later(data,handler,signal,info,context);
489 arch_set_pseudo_atomic_interrupted(context);
495 store_signal_data_for_later (struct interrupt_data *data, void *handler,
497 siginfo_t *info, os_context_t *context)
499 data->pending_handler = handler;
500 data->pending_signal = signal;
502 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
504 /* the signal mask in the context (from before we were
505 * interrupted) is copied to be restored when
506 * run_deferred_handler happens. Then the usually-blocked
507 * signals are added to the mask in the context so that we are
508 * running with blocked signals when the handler returns */
509 sigemptyset(&(data->pending_mask));
510 memcpy(&(data->pending_mask),
511 os_context_sigmask_addr(context),
512 REAL_SIGSET_SIZE_BYTES);
513 sigaddset_blockable(os_context_sigmask_addr(context));
515 /* this is also called from gencgc alloc(), in which case
516 * there has been no signal and is therefore no context. */
519 sigaddset_blockable(&new);
520 sigprocmask(SIG_BLOCK,&new,&(data->pending_mask));
526 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
528 os_context_t *context = arch_os_get_context(&void_context);
529 struct thread *thread=arch_os_get_current_thread();
530 struct interrupt_data *data=thread->interrupt_data;
531 #ifdef LISP_FEATURE_LINUX
532 os_restore_fp_control(context);
534 if(maybe_defer_handler(interrupt_handle_now,data,
535 signal,info,context))
537 interrupt_handle_now(signal, info, context);
538 #ifdef LISP_FEATURE_DARWIN
539 /* Work around G5 bug */
540 sigreturn(void_context);
544 #ifdef LISP_FEATURE_SB_THREAD
546 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
548 os_context_t *context = arch_os_get_context(&void_context);
549 struct thread *thread=arch_os_get_current_thread();
550 struct interrupt_data *data=thread->interrupt_data;
554 if(maybe_defer_handler(sig_stop_for_gc_handler,data,
555 signal,info,context)) {
558 /* need the context stored so it can have registers scavenged */
559 fake_foreign_function_call(context);
562 for(i=1;i<NSIG;i++) sigaddset(&ss,i); /* Block everything. */
563 sigprocmask(SIG_BLOCK,&ss,0);
565 thread->state=STATE_STOPPED;
567 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
570 undo_fake_foreign_function_call(context);
575 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
577 os_context_t *context = arch_os_get_context(&void_context);
578 interrupt_handle_now(signal, info, context);
579 #ifdef LISP_FEATURE_DARWIN
580 sigreturn(void_context);
585 * stuff to detect and handle hitting the GC trigger
588 #ifndef LISP_FEATURE_GENCGC
589 /* since GENCGC has its own way to record trigger */
591 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
593 if (current_auto_gc_trigger == NULL)
596 void *badaddr=arch_get_bad_addr(signal,info,context);
597 return (badaddr >= (void *)current_auto_gc_trigger &&
598 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
603 /* manipulate the signal context and stack such that when the handler
604 * returns, it will call function instead of whatever it was doing
608 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
609 extern void post_signal_tramp(void);
610 void arrange_return_to_lisp_function(os_context_t *context, lispobj function)
612 #ifndef LISP_FEATURE_X86
613 void * fun=native_pointer(function);
614 void *code = &(((struct simple_fun *) fun)->code);
617 /* Build a stack frame showing `interrupted' so that the
618 * user's backtrace makes (as much) sense (as usual) */
619 #ifdef LISP_FEATURE_X86
620 /* Suppose the existence of some function that saved all
621 * registers, called call_into_lisp, then restored GP registers and
622 * returned. We shortcut this: fake the stack that call_into_lisp
623 * would see, then arrange to have it called directly. post_signal_tramp
624 * is the second half of this function
626 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
628 *(sp-14) = post_signal_tramp; /* return address for call_into_lisp */
629 *(sp-13) = function; /* args for call_into_lisp : function*/
630 *(sp-12) = 0; /* arg array */
631 *(sp-11) = 0; /* no. args */
632 /* this order matches that used in POPAD */
633 *(sp-10)=*os_context_register_addr(context,reg_EDI);
634 *(sp-9)=*os_context_register_addr(context,reg_ESI);
635 /* this gets overwritten again before it's used, anyway */
636 *(sp-8)=*os_context_register_addr(context,reg_EBP);
637 *(sp-7)=0 ; /* POPAD doesn't set ESP, but expects a gap for it anyway */
638 *(sp-6)=*os_context_register_addr(context,reg_EBX);
640 *(sp-5)=*os_context_register_addr(context,reg_EDX);
641 *(sp-4)=*os_context_register_addr(context,reg_ECX);
642 *(sp-3)=*os_context_register_addr(context,reg_EAX);
643 *(sp-2)=*os_context_register_addr(context,reg_EBP);
644 *(sp-1)=*os_context_pc_addr(context);
647 struct thread *th=arch_os_get_current_thread();
648 build_fake_control_stack_frames(th,context);
651 #ifdef LISP_FEATURE_X86
652 *os_context_pc_addr(context) = call_into_lisp;
653 *os_context_register_addr(context,reg_ECX) = 0;
654 *os_context_register_addr(context,reg_EBP) = sp-2;
655 *os_context_register_addr(context,reg_ESP) = sp-14;
657 /* this much of the calling convention is common to all
659 *os_context_pc_addr(context) = code;
660 *os_context_register_addr(context,reg_NARGS) = 0;
661 *os_context_register_addr(context,reg_LIP) = code;
662 *os_context_register_addr(context,reg_CFP) =
663 current_control_frame_pointer;
665 #ifdef ARCH_HAS_NPC_REGISTER
666 *os_context_npc_addr(context) =
667 4 + *os_context_pc_addr(context);
669 #ifdef LISP_FEATURE_SPARC
670 *os_context_register_addr(context,reg_CODE) =
671 fun + FUN_POINTER_LOWTAG;
675 #ifdef LISP_FEATURE_SB_THREAD
676 void interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
678 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
679 struct thread *th=arch_os_get_current_thread();
680 struct interrupt_data *data=
681 th ? th->interrupt_data : global_interrupt_data;
682 if(maybe_defer_handler(interrupt_thread_handler,data,num,info,context)){
685 arrange_return_to_lisp_function(context,info->si_value.sival_int);
688 void thread_exit_handler(int num, siginfo_t *info, void *v_context)
689 { /* called when a child thread exits */
694 kid=waitpid(-1,&status,__WALL|WNOHANG);
696 if(WIFEXITED(status) || WIFSIGNALED(status)) {
697 struct thread *th=find_thread_by_pid(kid);
698 if(th) th->state=STATE_DEAD;
706 boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr){
707 struct thread *th=arch_os_get_current_thread();
708 /* note the os_context hackery here. When the signal handler returns,
709 * it won't go back to what it was doing ... */
710 if(addr>=(void *)CONTROL_STACK_GUARD_PAGE(th) &&
711 addr<(void *)(CONTROL_STACK_GUARD_PAGE(th)+os_vm_page_size)) {
712 /* we hit the end of the control stack. disable protection
713 * temporarily so the error handler has some headroom */
714 protect_control_stack_guard_page(th->pid,0L);
716 arrange_return_to_lisp_function
717 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
723 #ifndef LISP_FEATURE_GENCGC
724 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
725 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
726 * whether the signal was due to treading on the mprotect()ed zone -
727 * and if so, arrange for a GC to happen. */
728 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
731 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
733 os_context_t *context=(os_context_t *) void_context;
734 struct thread *th=arch_os_get_current_thread();
735 struct interrupt_data *data=
736 th ? th->interrupt_data : global_interrupt_data;
738 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
739 clear_auto_gc_trigger();
740 if(!maybe_defer_handler
741 (interrupt_maybe_gc_int,data,signal,info,void_context))
742 interrupt_maybe_gc_int(signal,info,void_context);
750 /* this is also used by gencgc, in alloc() */
752 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
755 os_context_t *context=(os_context_t *) void_context;
756 fake_foreign_function_call(context);
757 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
758 * which case we will be running with no gc trigger barrier
759 * thing for a while. But it shouldn't be long until the end
760 * of WITHOUT-GCING. */
763 sigaddset_blockable(&new);
764 /* enable signals before calling into Lisp */
765 sigprocmask(SIG_UNBLOCK,&new,0);
766 funcall0(SymbolFunction(SUB_GC));
767 undo_fake_foreign_function_call(context);
773 * noise to install handlers
777 undoably_install_low_level_interrupt_handler (int signal,
783 struct thread *th=arch_os_get_current_thread();
784 struct interrupt_data *data=
785 th ? th->interrupt_data : global_interrupt_data;
787 if (0 > signal || signal >= NSIG) {
788 lose("bad signal number %d", signal);
791 sa.sa_sigaction = handler;
792 sigemptyset(&sa.sa_mask);
793 sigaddset_blockable(&sa.sa_mask);
794 sa.sa_flags = SA_SIGINFO | SA_RESTART;
795 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
796 if((signal==SIG_MEMORY_FAULT)
797 #ifdef SIG_INTERRUPT_THREAD
798 || (signal==SIG_INTERRUPT_THREAD)
801 sa.sa_flags|= SA_ONSTACK;
804 sigaction(signal, &sa, NULL);
805 data->interrupt_low_level_handlers[signal] =
806 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
809 /* This is called from Lisp. */
811 install_handler(int signal, void handler(int, siginfo_t*, void*))
815 union interrupt_handler oldhandler;
816 struct thread *th=arch_os_get_current_thread();
817 struct interrupt_data *data=
818 th ? th->interrupt_data : global_interrupt_data;
820 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
823 sigaddset(&new, signal);
824 sigprocmask(SIG_BLOCK, &new, &old);
827 sigaddset_blockable(&new);
829 FSHOW((stderr, "/data->interrupt_low_level_handlers[signal]=%d\n",
830 data->interrupt_low_level_handlers[signal]));
831 if (data->interrupt_low_level_handlers[signal]==0) {
832 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
833 ARE_SAME_HANDLER(handler, SIG_IGN)) {
834 sa.sa_sigaction = handler;
835 } else if (sigismember(&new, signal)) {
836 sa.sa_sigaction = maybe_now_maybe_later;
838 sa.sa_sigaction = interrupt_handle_now_handler;
841 sigemptyset(&sa.sa_mask);
842 sigaddset_blockable(&sa.sa_mask);
843 sa.sa_flags = SA_SIGINFO | SA_RESTART;
844 sigaction(signal, &sa, NULL);
847 oldhandler = data->interrupt_handlers[signal];
848 data->interrupt_handlers[signal].c = handler;
850 sigprocmask(SIG_SETMASK, &old, 0);
852 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
854 return (unsigned long)oldhandler.lisp;
861 SHOW("entering interrupt_init()");
862 global_interrupt_data=calloc(sizeof(struct interrupt_data), 1);
864 /* Set up high level handler information. */
865 for (i = 0; i < NSIG; i++) {
866 global_interrupt_data->interrupt_handlers[i].c =
867 /* (The cast here blasts away the distinction between
868 * SA_SIGACTION-style three-argument handlers and
869 * signal(..)-style one-argument handlers, which is OK
870 * because it works to call the 1-argument form where the
871 * 3-argument form is expected.) */
872 (void (*)(int, siginfo_t*, void*))SIG_DFL;
875 SHOW("returning from interrupt_init()");