2 * interrupt-handling magic
6 * This software is part of the SBCL system. See the README file for
9 * This software is derived from the CMU CL system, which was
10 * written at Carnegie Mellon University and released into the
11 * public domain. The software is in the public domain and is
12 * provided with absolutely no warranty. See the COPYING and CREDITS
13 * files for more information.
17 /* As far as I can tell, what's going on here is:
19 * In the case of most signals, when Lisp asks us to handle the
20 * signal, the outermost handler (the one actually passed to UNIX) is
21 * either interrupt_handle_now(..) or maybe_now_maybe_later(..).
22 * In that case, the Lisp-level handler is stored in interrupt_handlers[..]
23 * and interrupt_low_level_handlers[..] is cleared.
25 * However, some signals need special handling, e.g.
27 * o the SIGSEGV (for e.g. Linux) or SIGBUS (for e.g. FreeBSD) used by the
28 * garbage collector to detect violations of write protection,
29 * because some cases of such signals (e.g. GC-related violations of
30 * write protection) are handled at C level and never passed on to
31 * Lisp. For such signals, we still store any Lisp-level handler
32 * in interrupt_handlers[..], but for the outermost handle we use
33 * the value from interrupt_low_level_handlers[..], instead of the
34 * ordinary interrupt_handle_now(..) or interrupt_handle_later(..).
36 * o the SIGTRAP (Linux/Alpha) which Lisp code uses to handle breakpoints,
37 * pseudo-atomic sections, and some classes of error (e.g. "function
38 * not defined"). This never goes anywhere near the Lisp handlers at all.
39 * See runtime/alpha-arch.c and code/signal.lisp
41 * - WHN 20000728, dan 20010128 */
48 #include <sys/types.h>
56 #include "interrupt.h"
65 #include "genesis/fdefn.h"
66 #include "genesis/simple-fun.h"
67 #include "genesis/cons.h"
71 void run_deferred_handler(struct interrupt_data *data, void *v_context) ;
72 static void store_signal_data_for_later (struct interrupt_data *data,
73 void *handler, int signal,
75 os_context_t *context);
76 boolean interrupt_maybe_gc_int(int signal, siginfo_t *info, void *v_context);
78 void sigaddset_deferrable(sigset_t *s)
82 sigaddset(s, SIGQUIT);
83 sigaddset(s, SIGPIPE);
84 sigaddset(s, SIGALRM);
86 sigaddset(s, SIGTSTP);
87 sigaddset(s, SIGCHLD);
89 sigaddset(s, SIGXCPU);
90 sigaddset(s, SIGXFSZ);
91 sigaddset(s, SIGVTALRM);
92 sigaddset(s, SIGPROF);
93 sigaddset(s, SIGWINCH);
94 sigaddset(s, SIGUSR1);
95 sigaddset(s, SIGUSR2);
96 #ifdef LISP_FEATURE_SB_THREAD
97 sigaddset(s, SIG_INTERRUPT_THREAD);
101 void sigaddset_blockable(sigset_t *s)
103 sigaddset_deferrable(s);
104 #ifdef LISP_FEATURE_SB_THREAD
105 sigaddset(s, SIG_STOP_FOR_GC);
109 /* initialized in interrupt_init */
110 static sigset_t deferrable_sigset;
111 static sigset_t blockable_sigset;
113 inline static void check_blockables_blocked_or_lose()
115 /* Get the current sigmask, by blocking the empty set. */
116 sigset_t empty,current;
119 thread_sigmask(SIG_BLOCK, &empty, ¤t);
120 for(i=0;i<NSIG;i++) {
121 if (sigismember(&blockable_sigset, i) && !sigismember(¤t, i))
122 lose("blockable signal %d not blocked",i);
126 inline static void check_interrupts_enabled_or_lose(os_context_t *context)
128 struct thread *thread=arch_os_get_current_thread();
129 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL)
130 lose("interrupts not enabled");
132 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
133 (!foreign_function_call_active) &&
135 arch_pseudo_atomic_atomic(context))
136 lose ("in pseudo atomic section");
139 /* When we catch an internal error, should we pass it back to Lisp to
140 * be handled in a high-level way? (Early in cold init, the answer is
141 * 'no', because Lisp is still too brain-dead to handle anything.
142 * After sufficient initialization has been completed, the answer
144 boolean internal_errors_enabled = 0;
146 static void (*interrupt_low_level_handlers[NSIG]) (int, siginfo_t*, void*);
147 union interrupt_handler interrupt_handlers[NSIG];
149 /* At the toplevel repl we routinely call this function. The signal
150 * mask ought to be clear anyway most of the time, but may be non-zero
151 * if we were interrupted e.g. while waiting for a queue. */
153 void reset_signal_mask ()
157 thread_sigmask(SIG_SETMASK,&new,0);
160 void block_blockable_signals ()
164 sigaddset_blockable(&block);
165 thread_sigmask(SIG_BLOCK, &block, 0);
170 * utility routines used by various signal handlers
174 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
176 #ifndef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
180 /* Build a fake stack frame or frames */
182 current_control_frame_pointer =
183 (lispobj *)(unsigned long)
184 (*os_context_register_addr(context, reg_CSP));
185 if ((lispobj *)(unsigned long)
186 (*os_context_register_addr(context, reg_CFP))
187 == current_control_frame_pointer) {
188 /* There is a small window during call where the callee's
189 * frame isn't built yet. */
190 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
191 == FUN_POINTER_LOWTAG) {
192 /* We have called, but not built the new frame, so
193 * build it for them. */
194 current_control_frame_pointer[0] =
195 *os_context_register_addr(context, reg_OCFP);
196 current_control_frame_pointer[1] =
197 *os_context_register_addr(context, reg_LRA);
198 current_control_frame_pointer += 8;
199 /* Build our frame on top of it. */
200 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
203 /* We haven't yet called, build our frame as if the
204 * partial frame wasn't there. */
205 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
208 /* We can't tell whether we are still in the caller if it had to
209 * allocate a stack frame due to stack arguments. */
210 /* This observation provoked some past CMUCL maintainer to ask
211 * "Can anything strange happen during return?" */
214 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
217 current_control_stack_pointer = current_control_frame_pointer + 8;
219 current_control_frame_pointer[0] = oldcont;
220 current_control_frame_pointer[1] = NIL;
221 current_control_frame_pointer[2] =
222 (lispobj)(*os_context_register_addr(context, reg_CODE));
227 fake_foreign_function_call(os_context_t *context)
230 struct thread *thread=arch_os_get_current_thread();
232 /* context_index incrementing must not be interrupted */
233 check_blockables_blocked_or_lose();
235 /* Get current Lisp state from context. */
237 dynamic_space_free_pointer =
238 (lispobj *)(unsigned long)
239 (*os_context_register_addr(context, reg_ALLOC));
240 #if defined(LISP_FEATURE_ALPHA)
241 if ((long)dynamic_space_free_pointer & 1) {
242 lose("dead in fake_foreign_function_call, context = %x", context);
247 current_binding_stack_pointer =
248 (lispobj *)(unsigned long)
249 (*os_context_register_addr(context, reg_BSP));
252 build_fake_control_stack_frames(thread,context);
254 /* Do dynamic binding of the active interrupt context index
255 * and save the context in the context array. */
257 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
259 if (context_index >= MAX_INTERRUPTS) {
260 lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS);
263 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
264 make_fixnum(context_index + 1),thread);
266 thread->interrupt_contexts[context_index] = context;
268 /* no longer in Lisp now */
269 foreign_function_call_active = 1;
272 /* blocks all blockable signals. If you are calling from a signal handler,
273 * the usual signal mask will be restored from the context when the handler
274 * finishes. Otherwise, be careful */
277 undo_fake_foreign_function_call(os_context_t *context)
279 struct thread *thread=arch_os_get_current_thread();
280 /* Block all blockable signals. */
281 block_blockable_signals();
283 /* going back into Lisp */
284 foreign_function_call_active = 0;
286 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
290 /* Put the dynamic space free pointer back into the context. */
291 *os_context_register_addr(context, reg_ALLOC) =
292 (unsigned long) dynamic_space_free_pointer;
296 /* a handler for the signal caused by execution of a trap opcode
297 * signalling an internal error */
299 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
302 lispobj context_sap = 0;
304 check_blockables_blocked_or_lose();
305 fake_foreign_function_call(context);
307 /* Allocate the SAP object while the interrupts are still
309 if (internal_errors_enabled) {
310 context_sap = alloc_sap(context);
313 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
315 if (internal_errors_enabled) {
316 SHOW("in interrupt_internal_error");
318 /* Display some rudimentary debugging information about the
319 * error, so that even if the Lisp error handler gets badly
320 * confused, we have a chance to determine what's going on. */
321 describe_internal_error(context);
323 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
324 continuable ? T : NIL);
326 describe_internal_error(context);
327 /* There's no good way to recover from an internal error
328 * before the Lisp error handling mechanism is set up. */
329 lose("internal error too early in init, can't recover");
331 undo_fake_foreign_function_call(context); /* blocks signals again */
333 arch_skip_instruction(context);
338 interrupt_handle_pending(os_context_t *context)
340 struct thread *thread;
341 struct interrupt_data *data;
343 check_blockables_blocked_or_lose();
345 thread=arch_os_get_current_thread();
346 data=thread->interrupt_data;
348 if (SymbolValue(GC_INHIBIT,thread)==NIL) {
349 #ifdef LISP_FEATURE_SB_THREAD
350 if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
351 /* another thread has already initiated a gc, this attempt
352 * might as well be cancelled */
353 SetSymbolValue(GC_PENDING,NIL,thread);
354 SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
355 sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
358 if (SymbolValue(GC_PENDING,thread) != NIL) {
359 /* GC_PENDING is cleared in SUB-GC, or if another thread
360 * is doing a gc already we will get a SIG_STOP_FOR_GC and
361 * that will clear it. */
362 interrupt_maybe_gc_int(0,NULL,context);
364 check_blockables_blocked_or_lose();
367 /* we may be here only to do the gc stuff, if interrupts are
368 * enabled run the pending handler */
369 if (!((SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) ||
371 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
372 (!foreign_function_call_active) &&
374 arch_pseudo_atomic_atomic(context)))) {
376 /* There may be no pending handler, because it was only a gc
377 * that had to be executed or because pseudo atomic triggered
378 * twice for a single interrupt. For the interested reader,
379 * that may happen if an interrupt hits after the interrupted
380 * flag is cleared but before pseduo-atomic is set and a
381 * pseudo atomic is interrupted in that interrupt. */
382 if (data->pending_handler) {
384 /* If we're here as the result of a pseudo-atomic as opposed
385 * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
386 * NIL, because maybe_defer_handler sets
387 * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
388 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
390 /* restore the saved signal mask from the original signal (the
391 * one that interrupted us during the critical section) into the
392 * os_context for the signal we're currently in the handler for.
393 * This should ensure that when we return from the handler the
394 * blocked signals are unblocked */
395 sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
397 sigemptyset(&data->pending_mask);
398 /* This will break on sparc linux: the deferred handler really wants
399 * to be called with a void_context */
400 run_deferred_handler(data,(void *)context);
406 * the two main signal handlers:
407 * interrupt_handle_now(..)
408 * maybe_now_maybe_later(..)
410 * to which we have added interrupt_handle_now_handler(..). Why?
411 * Well, mostly because the SPARC/Linux platform doesn't quite do
412 * signals the way we want them done. The third argument in the
413 * handler isn't filled in by the kernel properly, so we fix it up
414 * ourselves in the arch_os_get_context(..) function; however, we only
415 * want to do this when we first hit the handler, and not when
416 * interrupt_handle_now(..) is being called from some other handler
417 * (when the fixup will already have been done). -- CSR, 2002-07-23
421 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
423 os_context_t *context = (os_context_t*)void_context;
424 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
425 boolean were_in_lisp;
427 union interrupt_handler handler;
428 check_blockables_blocked_or_lose();
429 if (sigismember(&deferrable_sigset,signal))
430 check_interrupts_enabled_or_lose(context);
432 #ifdef LISP_FEATURE_LINUX
433 /* Under Linux on some architectures, we appear to have to restore
434 the FPU control word from the context, as after the signal is
435 delivered we appear to have a null FPU control word. */
436 os_restore_fp_control(context);
438 handler = interrupt_handlers[signal];
440 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
444 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
445 were_in_lisp = !foreign_function_call_active;
449 fake_foreign_function_call(context);
452 FSHOW_SIGNAL((stderr,
453 "/entering interrupt_handle_now(%d, info, context)\n",
456 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
458 /* This can happen if someone tries to ignore or default one
459 * of the signals we need for runtime support, and the runtime
460 * support decides to pass on it. */
461 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
463 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
464 /* Once we've decided what to do about contexts in a
465 * return-elsewhere world (the original context will no longer
466 * be available; should we copy it or was nobody using it anyway?)
467 * then we should convert this to return-elsewhere */
469 /* CMUCL comment said "Allocate the SAPs while the interrupts
470 * are still disabled.". I (dan, 2003.08.21) assume this is
471 * because we're not in pseudoatomic and allocation shouldn't
472 * be interrupted. In which case it's no longer an issue as
473 * all our allocation from C now goes through a PA wrapper,
474 * but still, doesn't hurt.
476 * Yeah, but non-gencgc platforms that don't really wrap
477 * allocation in PA. MG - 2005-08-29 */
479 lispobj info_sap,context_sap = alloc_sap(context);
480 info_sap = alloc_sap(info);
481 /* Allow signals again. */
482 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
484 FSHOW_SIGNAL((stderr,"/calling Lisp-level handler\n"));
486 funcall3(handler.lisp,
492 FSHOW_SIGNAL((stderr,"/calling C-level handler\n"));
494 /* Allow signals again. */
495 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
497 (*handler.c)(signal, info, void_context);
500 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
504 undo_fake_foreign_function_call(context); /* block signals again */
507 FSHOW_SIGNAL((stderr,
508 "/returning from interrupt_handle_now(%d, info, context)\n",
512 /* This is called at the end of a critical section if the indications
513 * are that some signal was deferred during the section. Note that as
514 * far as C or the kernel is concerned we dealt with the signal
515 * already; we're just doing the Lisp-level processing now that we
519 run_deferred_handler(struct interrupt_data *data, void *v_context) {
520 /* The pending_handler may enable interrupts and then another
521 * interrupt may hit, overwrite interrupt_data, so reset the
522 * pending handler before calling it. Trust the handler to finish
523 * with the siginfo before enabling interrupts. */
524 void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
525 data->pending_handler=0;
526 (*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
530 maybe_defer_handler(void *handler, struct interrupt_data *data,
531 int signal, siginfo_t *info, os_context_t *context)
533 struct thread *thread=arch_os_get_current_thread();
535 check_blockables_blocked_or_lose();
537 if (SymbolValue(INTERRUPT_PENDING,thread) != NIL)
538 lose("interrupt already pending");
539 /* If interrupts are disabled then INTERRUPT_PENDING is set and
540 * not PSEDUO_ATOMIC_INTERRUPTED. This is important for a pseudo
541 * atomic section inside a WITHOUT-INTERRUPTS.
543 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
544 store_signal_data_for_later(data,handler,signal,info,context);
545 SetSymbolValue(INTERRUPT_PENDING, T,thread);
546 FSHOW_SIGNAL((stderr,
547 "/maybe_defer_handler(%x,%d),thread=%lu: deferred\n",
548 (unsigned int)handler,signal,
549 (unsigned long)thread->os_thread));
552 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
553 * actually use its argument for anything on x86, so this branch
554 * may succeed even when context is null (gencgc alloc()) */
556 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
557 /* FIXME: this foreign_function_call_active test is dubious at
558 * best. If a foreign call is made in a pseudo atomic section
559 * (?) or more likely a pseudo atomic section is in a foreign
560 * call then an interrupt is executed immediately. Maybe it
561 * has to do with C code not maintaining pseudo atomic
562 * properly. MG - 2005-08-10 */
563 (!foreign_function_call_active) &&
565 arch_pseudo_atomic_atomic(context)) {
566 store_signal_data_for_later(data,handler,signal,info,context);
567 arch_set_pseudo_atomic_interrupted(context);
568 FSHOW_SIGNAL((stderr,
569 "/maybe_defer_handler(%x,%d),thread=%lu: deferred(PA)\n",
570 (unsigned int)handler,signal,
571 (unsigned long)thread->os_thread));
574 FSHOW_SIGNAL((stderr,
575 "/maybe_defer_handler(%x,%d),thread=%lu: not deferred\n",
576 (unsigned int)handler,signal,
577 (unsigned long)thread->os_thread));
582 store_signal_data_for_later (struct interrupt_data *data, void *handler,
584 siginfo_t *info, os_context_t *context)
586 if (data->pending_handler)
587 lose("tried to overwrite pending interrupt handler %x with %x\n",
588 data->pending_handler, handler);
590 lose("tried to defer null interrupt handler\n");
591 data->pending_handler = handler;
592 data->pending_signal = signal;
594 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
596 /* the signal mask in the context (from before we were
597 * interrupted) is copied to be restored when
598 * run_deferred_handler happens. Then the usually-blocked
599 * signals are added to the mask in the context so that we are
600 * running with blocked signals when the handler returns */
601 sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
602 sigaddset_deferrable(os_context_sigmask_addr(context));
607 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
609 os_context_t *context = arch_os_get_context(&void_context);
610 struct thread *thread=arch_os_get_current_thread();
611 struct interrupt_data *data=thread->interrupt_data;
612 #ifdef LISP_FEATURE_LINUX
613 os_restore_fp_control(context);
615 if(maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
617 interrupt_handle_now(signal, info, context);
618 #ifdef LISP_FEATURE_DARWIN
619 /* Work around G5 bug */
620 DARWIN_FIX_CONTEXT(context);
625 low_level_interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
627 os_context_t *context = (os_context_t*)void_context;
629 #ifdef LISP_FEATURE_LINUX
630 os_restore_fp_control(context);
632 check_blockables_blocked_or_lose();
633 check_interrupts_enabled_or_lose(context);
634 interrupt_low_level_handlers[signal](signal, info, void_context);
635 #ifdef LISP_FEATURE_DARWIN
636 /* Work around G5 bug */
637 DARWIN_FIX_CONTEXT(context);
642 low_level_maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
644 os_context_t *context = arch_os_get_context(&void_context);
645 struct thread *thread=arch_os_get_current_thread();
646 struct interrupt_data *data=thread->interrupt_data;
647 #ifdef LISP_FEATURE_LINUX
648 os_restore_fp_control(context);
650 if(maybe_defer_handler(low_level_interrupt_handle_now,data,
651 signal,info,context))
653 low_level_interrupt_handle_now(signal, info, context);
654 #ifdef LISP_FEATURE_DARWIN
655 /* Work around G5 bug */
656 DARWIN_FIX_CONTEXT(context);
660 #ifdef LISP_FEATURE_SB_THREAD
663 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
665 os_context_t *context = arch_os_get_context(&void_context);
666 struct thread *thread=arch_os_get_current_thread();
670 if ((arch_pseudo_atomic_atomic(context) ||
671 SymbolValue(GC_INHIBIT,thread) != NIL)) {
672 SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
673 if (SymbolValue(GC_INHIBIT,thread) == NIL)
674 arch_set_pseudo_atomic_interrupted(context);
675 FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred\n",
678 /* need the context stored so it can have registers scavenged */
679 fake_foreign_function_call(context);
682 for(i=1;i<NSIG;i++) sigaddset(&ss,i); /* Block everything. */
683 thread_sigmask(SIG_BLOCK,&ss,0);
685 /* The GC can't tell if a thread is a zombie, so this would be a
686 * good time to let the kernel reap any of our children in that
687 * awful state, to stop them from being waited for indefinitely.
688 * Userland reaping is done later when GC is finished */
689 if(thread->state!=STATE_RUNNING) {
690 lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
691 fixnum_value(thread->state));
693 thread->state=STATE_SUSPENDED;
694 FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
696 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
698 FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
699 if(thread->state!=STATE_RUNNING) {
700 lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
701 fixnum_value(thread->state));
704 undo_fake_foreign_function_call(context);
710 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
712 os_context_t *context = arch_os_get_context(&void_context);
713 interrupt_handle_now(signal, info, context);
714 #ifdef LISP_FEATURE_DARWIN
715 DARWIN_FIX_CONTEXT(context);
720 * stuff to detect and handle hitting the GC trigger
723 #ifndef LISP_FEATURE_GENCGC
724 /* since GENCGC has its own way to record trigger */
726 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
728 if (current_auto_gc_trigger == NULL)
731 void *badaddr=arch_get_bad_addr(signal,info,context);
732 return (badaddr >= (void *)current_auto_gc_trigger &&
733 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
738 /* manipulate the signal context and stack such that when the handler
739 * returns, it will call function instead of whatever it was doing
743 #if (defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
744 int *context_eflags_addr(os_context_t *context);
747 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
748 extern void post_signal_tramp(void);
749 void arrange_return_to_lisp_function(os_context_t *context, lispobj function)
751 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
752 void * fun=native_pointer(function);
753 void *code = &(((struct simple_fun *) fun)->code);
756 /* Build a stack frame showing `interrupted' so that the
757 * user's backtrace makes (as much) sense (as usual) */
759 /* FIXME: what about restoring fp state? */
760 /* FIXME: what about restoring errno? */
761 #ifdef LISP_FEATURE_X86
762 /* Suppose the existence of some function that saved all
763 * registers, called call_into_lisp, then restored GP registers and
764 * returned. It would look something like this:
772 pushl {address of function to call}
773 call 0x8058db0 <call_into_lisp>
780 * What we do here is set up the stack that call_into_lisp would
781 * expect to see if it had been called by this code, and frob the
782 * signal context so that signal return goes directly to call_into_lisp,
783 * and when that function (and the lisp function it invoked) returns,
784 * it returns to the second half of this imaginary function which
785 * restores all registers and returns to C
787 * For this to work, the latter part of the imaginary function
788 * must obviously exist in reality. That would be post_signal_tramp
791 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
793 /* return address for call_into_lisp: */
794 *(sp-15) = (u32)post_signal_tramp;
795 *(sp-14) = function; /* args for call_into_lisp : function*/
796 *(sp-13) = 0; /* arg array */
797 *(sp-12) = 0; /* no. args */
798 /* this order matches that used in POPAD */
799 *(sp-11)=*os_context_register_addr(context,reg_EDI);
800 *(sp-10)=*os_context_register_addr(context,reg_ESI);
802 *(sp-9)=*os_context_register_addr(context,reg_ESP)-8;
803 /* POPAD ignores the value of ESP: */
805 *(sp-7)=*os_context_register_addr(context,reg_EBX);
807 *(sp-6)=*os_context_register_addr(context,reg_EDX);
808 *(sp-5)=*os_context_register_addr(context,reg_ECX);
809 *(sp-4)=*os_context_register_addr(context,reg_EAX);
810 *(sp-3)=*context_eflags_addr(context);
811 *(sp-2)=*os_context_register_addr(context,reg_EBP);
812 *(sp-1)=*os_context_pc_addr(context);
814 #elif defined(LISP_FEATURE_X86_64)
815 u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
816 /* return address for call_into_lisp: */
817 *(sp-18) = (u64)post_signal_tramp;
819 *(sp-17)=*os_context_register_addr(context,reg_R15);
820 *(sp-16)=*os_context_register_addr(context,reg_R14);
821 *(sp-15)=*os_context_register_addr(context,reg_R13);
822 *(sp-14)=*os_context_register_addr(context,reg_R12);
823 *(sp-13)=*os_context_register_addr(context,reg_R11);
824 *(sp-12)=*os_context_register_addr(context,reg_R10);
825 *(sp-11)=*os_context_register_addr(context,reg_R9);
826 *(sp-10)=*os_context_register_addr(context,reg_R8);
827 *(sp-9)=*os_context_register_addr(context,reg_RDI);
828 *(sp-8)=*os_context_register_addr(context,reg_RSI);
829 /* skip RBP and RSP */
830 *(sp-7)=*os_context_register_addr(context,reg_RBX);
831 *(sp-6)=*os_context_register_addr(context,reg_RDX);
832 *(sp-5)=*os_context_register_addr(context,reg_RCX);
833 *(sp-4)=*os_context_register_addr(context,reg_RAX);
834 *(sp-3)=*context_eflags_addr(context);
835 *(sp-2)=*os_context_register_addr(context,reg_RBP);
836 *(sp-1)=*os_context_pc_addr(context);
838 *os_context_register_addr(context,reg_RDI) =
839 (os_context_register_t)function; /* function */
840 *os_context_register_addr(context,reg_RSI) = 0; /* arg. array */
841 *os_context_register_addr(context,reg_RDX) = 0; /* no. args */
843 struct thread *th=arch_os_get_current_thread();
844 build_fake_control_stack_frames(th,context);
847 #ifdef LISP_FEATURE_X86
848 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
849 *os_context_register_addr(context,reg_ECX) = 0;
850 *os_context_register_addr(context,reg_EBP) = (os_context_register_t)(sp-2);
852 *os_context_register_addr(context,reg_UESP) =
853 (os_context_register_t)(sp-15);
855 *os_context_register_addr(context,reg_ESP) = (os_context_register_t)(sp-15);
857 #elif defined(LISP_FEATURE_X86_64)
858 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
859 *os_context_register_addr(context,reg_RCX) = 0;
860 *os_context_register_addr(context,reg_RBP) = (os_context_register_t)(sp-2);
861 *os_context_register_addr(context,reg_RSP) = (os_context_register_t)(sp-18);
863 /* this much of the calling convention is common to all
865 *os_context_pc_addr(context) = (os_context_register_t)(unsigned long)code;
866 *os_context_register_addr(context,reg_NARGS) = 0;
867 *os_context_register_addr(context,reg_LIP) =
868 (os_context_register_t)(unsigned long)code;
869 *os_context_register_addr(context,reg_CFP) =
870 (os_context_register_t)(unsigned long)current_control_frame_pointer;
872 #ifdef ARCH_HAS_NPC_REGISTER
873 *os_context_npc_addr(context) =
874 4 + *os_context_pc_addr(context);
876 #ifdef LISP_FEATURE_SPARC
877 *os_context_register_addr(context,reg_CODE) =
878 (os_context_register_t)(fun + FUN_POINTER_LOWTAG);
882 #ifdef LISP_FEATURE_SB_THREAD
883 void interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
885 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
886 /* The order of interrupt execution is peculiar. If thread A
887 * interrupts thread B with I1, I2 and B for some reason receives
888 * I1 when FUN2 is already on the list, then it is FUN2 that gets
889 * to run first. But when FUN2 is run SIG_INTERRUPT_THREAD is
890 * enabled again and I2 hits pretty soon in FUN2 and run
891 * FUN1. This is of course just one scenario, and the order of
892 * thread interrupt execution is undefined. */
893 struct thread *th=arch_os_get_current_thread();
896 if (th->state != STATE_RUNNING)
897 lose("interrupt_thread_handler: thread %lu in wrong state: %d\n",
898 th->os_thread,fixnum_value(th->state));
899 get_spinlock(&th->interrupt_fun_lock,(long)th);
900 c=((struct cons *)native_pointer(th->interrupt_fun));
902 th->interrupt_fun=c->cdr;
903 release_spinlock(&th->interrupt_fun_lock);
905 lose("interrupt_thread_handler: NIL function\n");
906 arrange_return_to_lisp_function(context,function);
911 /* KLUDGE: Theoretically the approach we use for undefined alien
912 * variables should work for functions as well, but on PPC/Darwin
913 * we get bus error at bogus addresses instead, hence this workaround,
914 * that has the added benefit of automatically discriminating between
915 * functions and variables.
917 void undefined_alien_function() {
918 funcall0(SymbolFunction(UNDEFINED_ALIEN_FUNCTION_ERROR));
921 boolean handle_guard_page_triggered(os_context_t *context,os_vm_address_t addr)
923 struct thread *th=arch_os_get_current_thread();
925 /* note the os_context hackery here. When the signal handler returns,
926 * it won't go back to what it was doing ... */
927 if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
928 addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
929 /* We hit the end of the control stack: disable guard page
930 * protection so the error handler has some headroom, protect the
931 * previous page so that we can catch returns from the guard page
933 protect_control_stack_guard_page(th,0);
934 protect_control_stack_return_guard_page(th,1);
936 arrange_return_to_lisp_function
937 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
940 else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
941 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
942 /* We're returning from the guard page: reprotect it, and
943 * unprotect this one. This works even if we somehow missed
944 * the return-guard-page, and hit it on our way to new
945 * exhaustion instead. */
946 protect_control_stack_guard_page(th,1);
947 protect_control_stack_return_guard_page(th,0);
950 else if (addr >= undefined_alien_address &&
951 addr < undefined_alien_address + os_vm_page_size) {
952 arrange_return_to_lisp_function
953 (context, SymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
959 #ifndef LISP_FEATURE_GENCGC
960 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
961 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
962 * whether the signal was due to treading on the mprotect()ed zone -
963 * and if so, arrange for a GC to happen. */
964 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
967 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
969 os_context_t *context=(os_context_t *) void_context;
971 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
972 struct thread *thread=arch_os_get_current_thread();
973 clear_auto_gc_trigger();
974 /* Don't flood the system with interrupts if the need to gc is
975 * already noted. This can happen for example when SUB-GC
976 * allocates or after a gc triggered in a WITHOUT-GCING. */
977 if (SymbolValue(GC_PENDING,thread) == NIL) {
978 if (SymbolValue(GC_INHIBIT,thread) == NIL) {
979 if (arch_pseudo_atomic_atomic(context)) {
980 /* set things up so that GC happens when we finish
982 SetSymbolValue(GC_PENDING,T,thread);
983 arch_set_pseudo_atomic_interrupted(context);
985 interrupt_maybe_gc_int(signal,info,void_context);
988 SetSymbolValue(GC_PENDING,T,thread);
998 /* this is also used by gencgc, in alloc() */
1000 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
1002 os_context_t *context=(os_context_t *) void_context;
1003 struct thread *thread=arch_os_get_current_thread();
1005 check_blockables_blocked_or_lose();
1006 fake_foreign_function_call(context);
1008 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
1009 * which case we will be running with no gc trigger barrier
1010 * thing for a while. But it shouldn't be long until the end
1013 * FIXME: It would be good to protect the end of dynamic space
1014 * and signal a storage condition from there.
1017 /* Restore the signal mask from the interrupted context before
1018 * calling into Lisp if interrupts are enabled. Why not always?
1020 * Suppose there is a WITHOUT-INTERRUPTS block far, far out. If an
1021 * interrupt hits while in SUB-GC, it is deferred and the
1022 * os_context_sigmask of that interrupt is set to block further
1023 * deferrable interrupts (until the first one is
1024 * handled). Unfortunately, that context refers to this place and
1025 * when we return from here the signals will not be blocked.
1027 * A kludgy alternative is to propagate the sigmask change to the
1030 if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL)
1031 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
1032 #ifdef LISP_FEATURE_SB_THREAD
1035 sigaddset(&new,SIG_STOP_FOR_GC);
1036 thread_sigmask(SIG_UNBLOCK,&new,0);
1039 funcall0(SymbolFunction(SUB_GC));
1041 undo_fake_foreign_function_call(context);
1047 * noise to install handlers
1051 undoably_install_low_level_interrupt_handler (int signal,
1056 struct sigaction sa;
1058 if (0 > signal || signal >= NSIG) {
1059 lose("bad signal number %d", signal);
1062 if (sigismember(&deferrable_sigset,signal))
1063 sa.sa_sigaction = low_level_maybe_now_maybe_later;
1065 sa.sa_sigaction = handler;
1067 sigemptyset(&sa.sa_mask);
1068 sigaddset_blockable(&sa.sa_mask);
1069 sa.sa_flags = SA_SIGINFO | SA_RESTART;
1070 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
1071 if((signal==SIG_MEMORY_FAULT)
1072 #ifdef SIG_INTERRUPT_THREAD
1073 || (signal==SIG_INTERRUPT_THREAD)
1076 sa.sa_flags|= SA_ONSTACK;
1079 sigaction(signal, &sa, NULL);
1080 interrupt_low_level_handlers[signal] =
1081 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
1084 /* This is called from Lisp. */
1086 install_handler(int signal, void handler(int, siginfo_t*, void*))
1088 struct sigaction sa;
1090 union interrupt_handler oldhandler;
1092 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
1095 sigaddset(&new, signal);
1096 thread_sigmask(SIG_BLOCK, &new, &old);
1098 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%x\n",
1099 (unsigned int)interrupt_low_level_handlers[signal]));
1100 if (interrupt_low_level_handlers[signal]==0) {
1101 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
1102 ARE_SAME_HANDLER(handler, SIG_IGN)) {
1103 sa.sa_sigaction = handler;
1104 } else if (sigismember(&deferrable_sigset, signal)) {
1105 sa.sa_sigaction = maybe_now_maybe_later;
1107 sa.sa_sigaction = interrupt_handle_now_handler;
1110 sigemptyset(&sa.sa_mask);
1111 sigaddset_blockable(&sa.sa_mask);
1112 sa.sa_flags = SA_SIGINFO | SA_RESTART;
1113 sigaction(signal, &sa, NULL);
1116 oldhandler = interrupt_handlers[signal];
1117 interrupt_handlers[signal].c = handler;
1119 thread_sigmask(SIG_SETMASK, &old, 0);
1121 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
1123 return (unsigned long)oldhandler.lisp;
1130 SHOW("entering interrupt_init()");
1131 sigemptyset(&deferrable_sigset);
1132 sigemptyset(&blockable_sigset);
1133 sigaddset_deferrable(&deferrable_sigset);
1134 sigaddset_blockable(&blockable_sigset);
1136 /* Set up high level handler information. */
1137 for (i = 0; i < NSIG; i++) {
1138 interrupt_handlers[i].c =
1139 /* (The cast here blasts away the distinction between
1140 * SA_SIGACTION-style three-argument handlers and
1141 * signal(..)-style one-argument handlers, which is OK
1142 * because it works to call the 1-argument form where the
1143 * 3-argument form is expected.) */
1144 (void (*)(int, siginfo_t*, void*))SIG_DFL;
1147 SHOW("returning from interrupt_init()");