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. */
127 void reset_signal_mask ()
131 sigprocmask(SIG_SETMASK,&new,0);
138 * utility routines used by various signal handlers
142 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
144 #ifndef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
148 /* Build a fake stack frame or frames */
150 current_control_frame_pointer =
151 (lispobj *)(*os_context_register_addr(context, reg_CSP));
152 if ((lispobj *)(*os_context_register_addr(context, reg_CFP))
153 == current_control_frame_pointer) {
154 /* There is a small window during call where the callee's
155 * frame isn't built yet. */
156 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
157 == FUN_POINTER_LOWTAG) {
158 /* We have called, but not built the new frame, so
159 * build it for them. */
160 current_control_frame_pointer[0] =
161 *os_context_register_addr(context, reg_OCFP);
162 current_control_frame_pointer[1] =
163 *os_context_register_addr(context, reg_LRA);
164 current_control_frame_pointer += 8;
165 /* Build our frame on top of it. */
166 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
169 /* We haven't yet called, build our frame as if the
170 * partial frame wasn't there. */
171 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
174 /* We can't tell whether we are still in the caller if it had to
175 * allocate a stack frame due to stack arguments. */
176 /* This observation provoked some past CMUCL maintainer to ask
177 * "Can anything strange happen during return?" */
180 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
183 current_control_stack_pointer = current_control_frame_pointer + 8;
185 current_control_frame_pointer[0] = oldcont;
186 current_control_frame_pointer[1] = NIL;
187 current_control_frame_pointer[2] =
188 (lispobj)(*os_context_register_addr(context, reg_CODE));
193 fake_foreign_function_call(os_context_t *context)
196 struct thread *thread=arch_os_get_current_thread();
198 /* Get current Lisp state from context. */
200 dynamic_space_free_pointer =
201 (lispobj *)(*os_context_register_addr(context, reg_ALLOC));
202 #if defined(LISP_FEATURE_ALPHA)
203 if ((long)dynamic_space_free_pointer & 1) {
204 lose("dead in fake_foreign_function_call, context = %x", context);
209 current_binding_stack_pointer =
210 (lispobj *)(*os_context_register_addr(context, reg_BSP));
213 build_fake_control_stack_frames(thread,context);
215 /* Do dynamic binding of the active interrupt context index
216 * and save the context in the context array. */
218 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
220 if (context_index >= MAX_INTERRUPTS) {
221 lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS);
224 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
225 make_fixnum(context_index + 1),thread);
227 thread->interrupt_contexts[context_index] = context;
229 /* no longer in Lisp now */
230 foreign_function_call_active = 1;
233 /* blocks all blockable signals. If you are calling from a signal handler,
234 * the usual signal mask will be restored from the context when the handler
235 * finishes. Otherwise, be careful */
238 undo_fake_foreign_function_call(os_context_t *context)
240 struct thread *thread=arch_os_get_current_thread();
241 /* Block all blockable signals. */
244 sigaddset_blockable(&block);
245 sigprocmask(SIG_BLOCK, &block, 0);
247 /* going back into Lisp */
248 foreign_function_call_active = 0;
250 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
254 /* Put the dynamic space free pointer back into the context. */
255 *os_context_register_addr(context, reg_ALLOC) =
256 (unsigned long) dynamic_space_free_pointer;
260 /* a handler for the signal caused by execution of a trap opcode
261 * signalling an internal error */
263 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
266 lispobj context_sap = 0;
268 fake_foreign_function_call(context);
270 /* Allocate the SAP object while the interrupts are still
272 if (internal_errors_enabled) {
273 context_sap = alloc_sap(context);
276 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
278 if (internal_errors_enabled) {
279 SHOW("in interrupt_internal_error");
281 /* Display some rudimentary debugging information about the
282 * error, so that even if the Lisp error handler gets badly
283 * confused, we have a chance to determine what's going on. */
284 describe_internal_error(context);
286 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
287 continuable ? T : NIL);
289 describe_internal_error(context);
290 /* There's no good way to recover from an internal error
291 * before the Lisp error handling mechanism is set up. */
292 lose("internal error too early in init, can't recover");
294 undo_fake_foreign_function_call(context); /* blocks signals again */
296 arch_skip_instruction(context);
301 interrupt_handle_pending(os_context_t *context)
303 struct thread *thread;
304 struct interrupt_data *data;
306 thread=arch_os_get_current_thread();
307 data=thread->interrupt_data;
308 /* FIXME I'm not altogether sure this is appropriate if we're
309 * here as the result of a pseudo-atomic */
310 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
312 /* restore the saved signal mask from the original signal (the
313 * one that interrupted us during the critical section) into the
314 * os_context for the signal we're currently in the handler for.
315 * This should ensure that when we return from the handler the
316 * blocked signals are unblocked */
318 memcpy(os_context_sigmask_addr(context), &data->pending_mask,
319 REAL_SIGSET_SIZE_BYTES);
321 sigemptyset(&data->pending_mask);
322 /* This will break on sparc linux: the deferred handler really wants
323 * to be called with a void_context */
324 run_deferred_handler(data,(void *)context);
328 * the two main signal handlers:
329 * interrupt_handle_now(..)
330 * maybe_now_maybe_later(..)
332 * to which we have added interrupt_handle_now_handler(..). Why?
333 * Well, mostly because the SPARC/Linux platform doesn't quite do
334 * signals the way we want them done. The third argument in the
335 * handler isn't filled in by the kernel properly, so we fix it up
336 * ourselves in the arch_os_get_context(..) function; however, we only
337 * want to do this when we first hit the handler, and not when
338 * interrupt_handle_now(..) is being called from some other handler
339 * (when the fixup will already have been done). -- CSR, 2002-07-23
343 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
345 os_context_t *context = (os_context_t*)void_context;
346 struct thread *thread=arch_os_get_current_thread();
347 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
348 boolean were_in_lisp;
350 union interrupt_handler handler;
352 #ifdef LISP_FEATURE_LINUX
353 /* Under Linux on some architectures, we appear to have to restore
354 the FPU control word from the context, as after the signal is
355 delivered we appear to have a null FPU control word. */
356 os_restore_fp_control(context);
358 handler = thread->interrupt_data->interrupt_handlers[signal];
360 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
364 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
365 were_in_lisp = !foreign_function_call_active;
369 fake_foreign_function_call(context);
374 "/entering interrupt_handle_now(%d, info, context)\n",
378 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
380 /* This can happen if someone tries to ignore or default one
381 * of the signals we need for runtime support, and the runtime
382 * support decides to pass on it. */
383 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
385 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
386 /* Once we've decided what to do about contexts in a
387 * return-elsewhere world (the original context will no longer
388 * be available; should we copy it or was nobody using it anyway?)
389 * then we should convert this to return-elsewhere */
391 /* CMUCL comment said "Allocate the SAPs while the interrupts
392 * are still disabled.". I (dan, 2003.08.21) assume this is
393 * because we're not in pseudoatomic and allocation shouldn't
394 * be interrupted. In which case it's no longer an issue as
395 * all our allocation from C now goes through a PA wrapper,
396 * but still, doesn't hurt */
398 lispobj info_sap,context_sap = alloc_sap(context);
399 info_sap = alloc_sap(info);
400 /* Allow signals again. */
401 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
404 SHOW("calling Lisp-level handler");
407 funcall3(handler.lisp,
414 SHOW("calling C-level handler");
417 /* Allow signals again. */
418 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
420 (*handler.c)(signal, info, void_context);
423 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
427 undo_fake_foreign_function_call(context); /* block signals again */
432 "/returning from interrupt_handle_now(%d, info, context)\n",
437 /* This is called at the end of a critical section if the indications
438 * are that some signal was deferred during the section. Note that as
439 * far as C or the kernel is concerned we dealt with the signal
440 * already; we're just doing the Lisp-level processing now that we
444 run_deferred_handler(struct interrupt_data *data, void *v_context) {
445 (*(data->pending_handler))
446 (data->pending_signal,&(data->pending_info), v_context);
447 data->pending_handler=0;
451 maybe_defer_handler(void *handler, struct interrupt_data *data,
452 int signal, siginfo_t *info, os_context_t *context)
454 struct thread *thread=arch_os_get_current_thread();
455 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
456 store_signal_data_for_later(data,handler,signal,info,context);
457 SetSymbolValue(INTERRUPT_PENDING, T,thread);
460 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
461 * actually use its argument for anything on x86, so this branch
462 * may succeed even when context is null (gencgc alloc()) */
464 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
465 (!foreign_function_call_active) &&
467 arch_pseudo_atomic_atomic(context)) {
468 store_signal_data_for_later(data,handler,signal,info,context);
469 arch_set_pseudo_atomic_interrupted(context);
475 store_signal_data_for_later (struct interrupt_data *data, void *handler,
477 siginfo_t *info, os_context_t *context)
479 data->pending_handler = handler;
480 data->pending_signal = signal;
482 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
484 /* the signal mask in the context (from before we were
485 * interrupted) is copied to be restored when
486 * run_deferred_handler happens. Then the usually-blocked
487 * signals are added to the mask in the context so that we are
488 * running with blocked signals when the handler returns */
489 sigemptyset(&(data->pending_mask));
490 memcpy(&(data->pending_mask),
491 os_context_sigmask_addr(context),
492 REAL_SIGSET_SIZE_BYTES);
493 sigaddset_blockable(os_context_sigmask_addr(context));
495 /* this is also called from gencgc alloc(), in which case
496 * there has been no signal and is therefore no context. */
499 sigaddset_blockable(&new);
500 sigprocmask(SIG_BLOCK,&new,&(data->pending_mask));
506 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
508 os_context_t *context = arch_os_get_context(&void_context);
509 struct thread *thread=arch_os_get_current_thread();
510 struct interrupt_data *data=thread->interrupt_data;
511 #ifdef LISP_FEATURE_LINUX
512 os_restore_fp_control(context);
514 if(maybe_defer_handler(interrupt_handle_now,data,
515 signal,info,context))
517 interrupt_handle_now(signal, info, context);
518 #ifdef LISP_FEATURE_DARWIN
519 /* Work around G5 bug */
520 DARWIN_FIX_CONTEXT(context);
524 #ifdef LISP_FEATURE_SB_THREAD
526 sig_stop_for_gc_handler(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;
534 if(maybe_defer_handler(sig_stop_for_gc_handler,data,
535 signal,info,context)) {
538 /* need the context stored so it can have registers scavenged */
539 fake_foreign_function_call(context);
542 for(i=1;i<NSIG;i++) sigaddset(&ss,i); /* Block everything. */
543 sigprocmask(SIG_BLOCK,&ss,0);
545 /* The GC can't tell if a thread is a zombie, so this would be a
546 * good time to let the kernel reap any of our children in that
547 * awful state, to stop them from being waited for indefinitely.
548 * Userland reaping is done later when GC is finished */
551 thread->state=STATE_STOPPED;
553 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
556 undo_fake_foreign_function_call(context);
561 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
563 os_context_t *context = arch_os_get_context(&void_context);
564 interrupt_handle_now(signal, info, context);
565 #ifdef LISP_FEATURE_DARWIN
566 DARWIN_FIX_CONTEXT(context);
571 * stuff to detect and handle hitting the GC trigger
574 #ifndef LISP_FEATURE_GENCGC
575 /* since GENCGC has its own way to record trigger */
577 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
579 if (current_auto_gc_trigger == NULL)
582 void *badaddr=arch_get_bad_addr(signal,info,context);
583 return (badaddr >= (void *)current_auto_gc_trigger &&
584 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
589 /* manipulate the signal context and stack such that when the handler
590 * returns, it will call function instead of whatever it was doing
594 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
595 extern void post_signal_tramp(void);
596 void arrange_return_to_lisp_function(os_context_t *context, lispobj function)
598 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
599 void * fun=native_pointer(function);
600 void *code = &(((struct simple_fun *) fun)->code);
603 /* Build a stack frame showing `interrupted' so that the
604 * user's backtrace makes (as much) sense (as usual) */
605 #ifdef LISP_FEATURE_X86
606 /* Suppose the existence of some function that saved all
607 * registers, called call_into_lisp, then restored GP registers and
608 * returned. It would look something like this:
615 pushl {address of function to call}
616 call 0x8058db0 <call_into_lisp>
622 * What we do here is set up the stack that call_into_lisp would
623 * expect to see if it had been called by this code, and frob the
624 * signal context so that signal return goes directly to call_into_lisp,
625 * and when that function (and the lisp function it invoked) returns,
626 * it returns to the second half of this imaginary function which
627 * restores all registers and returns to C
629 * For this to work, the latter part of the imaginary function
630 * must obviously exist in reality. That would be post_signal_tramp
633 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
635 *(sp-14) = post_signal_tramp; /* return address for call_into_lisp */
636 *(sp-13) = function; /* args for call_into_lisp : function*/
637 *(sp-12) = 0; /* arg array */
638 *(sp-11) = 0; /* no. args */
639 /* this order matches that used in POPAD */
640 *(sp-10)=*os_context_register_addr(context,reg_EDI);
641 *(sp-9)=*os_context_register_addr(context,reg_ESI);
643 *(sp-8)=*os_context_register_addr(context,reg_ESP)-8;
645 *(sp-6)=*os_context_register_addr(context,reg_EBX);
647 *(sp-5)=*os_context_register_addr(context,reg_EDX);
648 *(sp-4)=*os_context_register_addr(context,reg_ECX);
649 *(sp-3)=*os_context_register_addr(context,reg_EAX);
650 *(sp-2)=*os_context_register_addr(context,reg_EBP);
651 *(sp-1)=*os_context_pc_addr(context);
653 #elif defined(LISP_FEATURE_X86_64)
654 u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
655 *(sp-19) = post_signal_tramp; /* return address for call_into_lisp */
657 *(sp-18)=*os_context_register_addr(context,reg_R15);
658 *(sp-17)=*os_context_register_addr(context,reg_R14);
659 *(sp-16)=*os_context_register_addr(context,reg_R13);
660 *(sp-15)=*os_context_register_addr(context,reg_R12);
661 *(sp-14)=*os_context_register_addr(context,reg_R11);
662 *(sp-13)=*os_context_register_addr(context,reg_R10);
663 *(sp-12)=*os_context_register_addr(context,reg_R9);
664 *(sp-11)=*os_context_register_addr(context,reg_R8);
665 *(sp-10)=*os_context_register_addr(context,reg_RDI);
666 *(sp-9)=*os_context_register_addr(context,reg_RSI);
667 *(sp-8)=*os_context_register_addr(context,reg_RSP)-16;
669 *(sp-6)=*os_context_register_addr(context,reg_RBX);
670 *(sp-5)=*os_context_register_addr(context,reg_RDX);
671 *(sp-4)=*os_context_register_addr(context,reg_RCX);
672 *(sp-3)=*os_context_register_addr(context,reg_RAX);
673 *(sp-2)=*os_context_register_addr(context,reg_RBP);
674 *(sp-1)=*os_context_pc_addr(context);
676 *os_context_register_addr(context,reg_RDI) = function; /* function */
677 *os_context_register_addr(context,reg_RSI) = 0; /* arg. array */
678 *os_context_register_addr(context,reg_RDX) = 0; /* no. args */
680 struct thread *th=arch_os_get_current_thread();
681 build_fake_control_stack_frames(th,context);
684 #ifdef LISP_FEATURE_X86
685 *os_context_pc_addr(context) = call_into_lisp;
686 *os_context_register_addr(context,reg_ECX) = 0;
687 *os_context_register_addr(context,reg_EBP) = sp-2;
689 *os_context_register_addr(context,reg_UESP) = sp-14;
691 *os_context_register_addr(context,reg_ESP) = sp-14;
693 #elif defined(LISP_FEATURE_X86_64)
694 *os_context_pc_addr(context) = call_into_lisp;
695 *os_context_register_addr(context,reg_RCX) = 0;
696 *os_context_register_addr(context,reg_RBP) = sp-2;
697 *os_context_register_addr(context,reg_RSP) = sp-19;
699 /* this much of the calling convention is common to all
701 *os_context_pc_addr(context) = code;
702 *os_context_register_addr(context,reg_NARGS) = 0;
703 *os_context_register_addr(context,reg_LIP) = code;
704 *os_context_register_addr(context,reg_CFP) =
705 current_control_frame_pointer;
707 #ifdef ARCH_HAS_NPC_REGISTER
708 *os_context_npc_addr(context) =
709 4 + *os_context_pc_addr(context);
711 #ifdef LISP_FEATURE_SPARC
712 *os_context_register_addr(context,reg_CODE) =
713 fun + FUN_POINTER_LOWTAG;
717 #ifdef LISP_FEATURE_SB_THREAD
718 void interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
720 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
721 struct thread *th=arch_os_get_current_thread();
722 struct interrupt_data *data=
723 th ? th->interrupt_data : global_interrupt_data;
724 if(maybe_defer_handler(interrupt_thread_handler,data,num,info,context)){
727 arrange_return_to_lisp_function(context,info->si_value.sival_int);
730 void thread_exit_handler(int num, siginfo_t *info, void *v_context)
731 { /* called when a child thread exits */
737 /* KLUDGE: Theoretically the approach we use for undefined alien
738 * variables should work for functions as well, but on PPC/Darwin
739 * we get bus error at bogus addresses instead, hence this workaround,
740 * that has the added benefit of automatically discriminating between
741 * functions and variables.
743 void undefined_alien_function() {
744 funcall0(SymbolFunction(UNDEFINED_ALIEN_FUNCTION_ERROR));
747 boolean handle_guard_page_triggered(os_context_t *context,void *addr){
748 struct thread *th=arch_os_get_current_thread();
750 /* note the os_context hackery here. When the signal handler returns,
751 * it won't go back to what it was doing ... */
752 if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
753 addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
754 /* We hit the end of the control stack: disable guard page
755 * protection so the error handler has some headroom, protect the
756 * previous page so that we can catch returns from the guard page
758 protect_control_stack_guard_page(th->pid,0);
759 protect_control_stack_return_guard_page(th->pid,1);
761 arrange_return_to_lisp_function
762 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
765 else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
766 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
767 /* We're returning from the guard page: reprotect it, and
768 * unprotect this one. This works even if we somehow missed
769 * the return-guard-page, and hit it on our way to new
770 * exhaustion instead. */
771 protect_control_stack_guard_page(th->pid,1);
772 protect_control_stack_return_guard_page(th->pid,0);
775 else if (addr >= undefined_alien_address &&
776 addr < undefined_alien_address + os_vm_page_size) {
777 arrange_return_to_lisp_function
778 (context, SymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
784 #ifndef LISP_FEATURE_GENCGC
785 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
786 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
787 * whether the signal was due to treading on the mprotect()ed zone -
788 * and if so, arrange for a GC to happen. */
789 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
792 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
794 os_context_t *context=(os_context_t *) void_context;
795 struct thread *th=arch_os_get_current_thread();
796 struct interrupt_data *data=
797 th ? th->interrupt_data : global_interrupt_data;
799 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
800 clear_auto_gc_trigger();
801 if(!maybe_defer_handler
802 (interrupt_maybe_gc_int,data,signal,info,void_context))
803 interrupt_maybe_gc_int(signal,info,void_context);
811 /* this is also used by gencgc, in alloc() */
813 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
816 os_context_t *context=(os_context_t *) void_context;
817 fake_foreign_function_call(context);
818 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
819 * which case we will be running with no gc trigger barrier
820 * thing for a while. But it shouldn't be long until the end
821 * of WITHOUT-GCING. */
824 sigaddset_blockable(&new);
825 /* enable signals before calling into Lisp */
826 sigprocmask(SIG_UNBLOCK,&new,0);
827 funcall0(SymbolFunction(SUB_GC));
828 undo_fake_foreign_function_call(context);
834 * noise to install handlers
838 undoably_install_low_level_interrupt_handler (int signal,
844 struct thread *th=arch_os_get_current_thread();
845 struct interrupt_data *data=
846 th ? th->interrupt_data : global_interrupt_data;
848 if (0 > signal || signal >= NSIG) {
849 lose("bad signal number %d", signal);
852 sa.sa_sigaction = handler;
853 sigemptyset(&sa.sa_mask);
854 sigaddset_blockable(&sa.sa_mask);
855 sa.sa_flags = SA_SIGINFO | SA_RESTART;
856 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
857 if((signal==SIG_MEMORY_FAULT)
858 #ifdef SIG_INTERRUPT_THREAD
859 || (signal==SIG_INTERRUPT_THREAD)
862 sa.sa_flags|= SA_ONSTACK;
865 sigaction(signal, &sa, NULL);
866 data->interrupt_low_level_handlers[signal] =
867 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
870 /* This is called from Lisp. */
872 install_handler(int signal, void handler(int, siginfo_t*, void*))
876 union interrupt_handler oldhandler;
877 struct thread *th=arch_os_get_current_thread();
878 struct interrupt_data *data=
879 th ? th->interrupt_data : global_interrupt_data;
881 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
884 sigaddset(&new, signal);
885 sigprocmask(SIG_BLOCK, &new, &old);
888 sigaddset_blockable(&new);
890 FSHOW((stderr, "/data->interrupt_low_level_handlers[signal]=%d\n",
891 data->interrupt_low_level_handlers[signal]));
892 if (data->interrupt_low_level_handlers[signal]==0) {
893 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
894 ARE_SAME_HANDLER(handler, SIG_IGN)) {
895 sa.sa_sigaction = handler;
896 } else if (sigismember(&new, signal)) {
897 sa.sa_sigaction = maybe_now_maybe_later;
899 sa.sa_sigaction = interrupt_handle_now_handler;
902 sigemptyset(&sa.sa_mask);
903 sigaddset_blockable(&sa.sa_mask);
904 sa.sa_flags = SA_SIGINFO | SA_RESTART;
905 sigaction(signal, &sa, NULL);
908 oldhandler = data->interrupt_handlers[signal];
909 data->interrupt_handlers[signal].c = handler;
911 sigprocmask(SIG_SETMASK, &old, 0);
913 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
915 return (unsigned long)oldhandler.lisp;
922 SHOW("entering interrupt_init()");
923 global_interrupt_data=calloc(sizeof(struct interrupt_data), 1);
925 /* Set up high level handler information. */
926 for (i = 0; i < NSIG; i++) {
927 global_interrupt_data->interrupt_handlers[i].c =
928 /* (The cast here blasts away the distinction between
929 * SA_SIGACTION-style three-argument handlers and
930 * signal(..)-style one-argument handlers, which is OK
931 * because it works to call the 1-argument form where the
932 * 3-argument form is expected.) */
933 (void (*)(int, siginfo_t*, void*))SIG_DFL;
936 SHOW("returning from interrupt_init()");