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(void)
157 thread_sigmask(SIG_SETMASK,&new,0);
160 void block_blockable_signals(void)
163 sigcopyset(&block, &blockable_sigset);
164 thread_sigmask(SIG_BLOCK, &block, 0);
169 * utility routines used by various signal handlers
173 build_fake_control_stack_frames(struct thread *th,os_context_t *context)
175 #ifndef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
179 /* Build a fake stack frame or frames */
181 current_control_frame_pointer =
182 (lispobj *)(unsigned long)
183 (*os_context_register_addr(context, reg_CSP));
184 if ((lispobj *)(unsigned long)
185 (*os_context_register_addr(context, reg_CFP))
186 == current_control_frame_pointer) {
187 /* There is a small window during call where the callee's
188 * frame isn't built yet. */
189 if (lowtag_of(*os_context_register_addr(context, reg_CODE))
190 == FUN_POINTER_LOWTAG) {
191 /* We have called, but not built the new frame, so
192 * build it for them. */
193 current_control_frame_pointer[0] =
194 *os_context_register_addr(context, reg_OCFP);
195 current_control_frame_pointer[1] =
196 *os_context_register_addr(context, reg_LRA);
197 current_control_frame_pointer += 8;
198 /* Build our frame on top of it. */
199 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
202 /* We haven't yet called, build our frame as if the
203 * partial frame wasn't there. */
204 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
207 /* We can't tell whether we are still in the caller if it had to
208 * allocate a stack frame due to stack arguments. */
209 /* This observation provoked some past CMUCL maintainer to ask
210 * "Can anything strange happen during return?" */
213 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
216 current_control_stack_pointer = current_control_frame_pointer + 8;
218 current_control_frame_pointer[0] = oldcont;
219 current_control_frame_pointer[1] = NIL;
220 current_control_frame_pointer[2] =
221 (lispobj)(*os_context_register_addr(context, reg_CODE));
226 fake_foreign_function_call(os_context_t *context)
229 struct thread *thread=arch_os_get_current_thread();
231 /* context_index incrementing must not be interrupted */
232 check_blockables_blocked_or_lose();
234 /* Get current Lisp state from context. */
236 dynamic_space_free_pointer =
237 (lispobj *)(unsigned long)
238 (*os_context_register_addr(context, reg_ALLOC));
239 #if defined(LISP_FEATURE_ALPHA)
240 if ((long)dynamic_space_free_pointer & 1) {
241 lose("dead in fake_foreign_function_call, context = %x", context);
246 current_binding_stack_pointer =
247 (lispobj *)(unsigned long)
248 (*os_context_register_addr(context, reg_BSP));
251 build_fake_control_stack_frames(thread,context);
253 /* Do dynamic binding of the active interrupt context index
254 * and save the context in the context array. */
256 fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,thread));
258 if (context_index >= MAX_INTERRUPTS) {
259 lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS);
262 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
263 make_fixnum(context_index + 1),thread);
265 thread->interrupt_contexts[context_index] = context;
267 /* no longer in Lisp now */
268 foreign_function_call_active = 1;
271 /* blocks all blockable signals. If you are calling from a signal handler,
272 * the usual signal mask will be restored from the context when the handler
273 * finishes. Otherwise, be careful */
276 undo_fake_foreign_function_call(os_context_t *context)
278 struct thread *thread=arch_os_get_current_thread();
279 /* Block all blockable signals. */
280 block_blockable_signals();
282 /* going back into Lisp */
283 foreign_function_call_active = 0;
285 /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
289 /* Put the dynamic space free pointer back into the context. */
290 *os_context_register_addr(context, reg_ALLOC) =
291 (unsigned long) dynamic_space_free_pointer;
295 /* a handler for the signal caused by execution of a trap opcode
296 * signalling an internal error */
298 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
301 lispobj context_sap = 0;
303 fake_foreign_function_call(context);
305 if (!internal_errors_enabled) {
306 describe_internal_error(context);
307 /* There's no good way to recover from an internal error
308 * before the Lisp error handling mechanism is set up. */
309 lose("internal error too early in init, can't recover");
312 /* Allocate the SAP object while the interrupts are still
314 context_sap = alloc_sap(context);
316 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
318 SHOW("in interrupt_internal_error");
320 /* Display some rudimentary debugging information about the
321 * error, so that even if the Lisp error handler gets badly
322 * confused, we have a chance to determine what's going on. */
323 describe_internal_error(context);
325 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
326 continuable ? T : NIL);
328 undo_fake_foreign_function_call(context); /* blocks signals again */
330 arch_skip_instruction(context);
335 interrupt_handle_pending(os_context_t *context)
337 struct thread *thread;
338 struct interrupt_data *data;
340 check_blockables_blocked_or_lose();
342 thread=arch_os_get_current_thread();
343 data=thread->interrupt_data;
345 if (SymbolValue(GC_INHIBIT,thread)==NIL) {
346 #ifdef LISP_FEATURE_SB_THREAD
347 if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
348 /* another thread has already initiated a gc, this attempt
349 * might as well be cancelled */
350 SetSymbolValue(GC_PENDING,NIL,thread);
351 SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
352 sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
355 if (SymbolValue(GC_PENDING,thread) != NIL) {
356 /* GC_PENDING is cleared in SUB-GC, or if another thread
357 * is doing a gc already we will get a SIG_STOP_FOR_GC and
358 * that will clear it. */
359 interrupt_maybe_gc_int(0,NULL,context);
361 check_blockables_blocked_or_lose();
364 /* we may be here only to do the gc stuff, if interrupts are
365 * enabled run the pending handler */
366 if (!((SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) ||
368 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
369 (!foreign_function_call_active) &&
371 arch_pseudo_atomic_atomic(context)))) {
373 /* There may be no pending handler, because it was only a gc
374 * that had to be executed or because pseudo atomic triggered
375 * twice for a single interrupt. For the interested reader,
376 * that may happen if an interrupt hits after the interrupted
377 * flag is cleared but before pseduo-atomic is set and a
378 * pseudo atomic is interrupted in that interrupt. */
379 if (data->pending_handler) {
381 /* If we're here as the result of a pseudo-atomic as opposed
382 * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
383 * NIL, because maybe_defer_handler sets
384 * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
385 SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
387 /* restore the saved signal mask from the original signal (the
388 * one that interrupted us during the critical section) into the
389 * os_context for the signal we're currently in the handler for.
390 * This should ensure that when we return from the handler the
391 * blocked signals are unblocked */
392 sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
394 sigemptyset(&data->pending_mask);
395 /* This will break on sparc linux: the deferred handler really wants
396 * to be called with a void_context */
397 run_deferred_handler(data,(void *)context);
403 * the two main signal handlers:
404 * interrupt_handle_now(..)
405 * maybe_now_maybe_later(..)
407 * to which we have added interrupt_handle_now_handler(..). Why?
408 * Well, mostly because the SPARC/Linux platform doesn't quite do
409 * signals the way we want them done. The third argument in the
410 * handler isn't filled in by the kernel properly, so we fix it up
411 * ourselves in the arch_os_get_context(..) function; however, we only
412 * want to do this when we first hit the handler, and not when
413 * interrupt_handle_now(..) is being called from some other handler
414 * (when the fixup will already have been done). -- CSR, 2002-07-23
418 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
420 os_context_t *context = (os_context_t*)void_context;
421 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
422 boolean were_in_lisp;
424 union interrupt_handler handler;
425 check_blockables_blocked_or_lose();
426 if (sigismember(&deferrable_sigset,signal))
427 check_interrupts_enabled_or_lose(context);
429 #ifdef LISP_FEATURE_LINUX
430 /* Under Linux on some architectures, we appear to have to restore
431 the FPU control word from the context, as after the signal is
432 delivered we appear to have a null FPU control word. */
433 os_restore_fp_control(context);
435 handler = interrupt_handlers[signal];
437 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
441 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
442 were_in_lisp = !foreign_function_call_active;
446 fake_foreign_function_call(context);
449 FSHOW_SIGNAL((stderr,
450 "/entering interrupt_handle_now(%d, info, context)\n",
453 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
455 /* This can happen if someone tries to ignore or default one
456 * of the signals we need for runtime support, and the runtime
457 * support decides to pass on it. */
458 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
460 } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) {
461 /* Once we've decided what to do about contexts in a
462 * return-elsewhere world (the original context will no longer
463 * be available; should we copy it or was nobody using it anyway?)
464 * then we should convert this to return-elsewhere */
466 /* CMUCL comment said "Allocate the SAPs while the interrupts
467 * are still disabled.". I (dan, 2003.08.21) assume this is
468 * because we're not in pseudoatomic and allocation shouldn't
469 * be interrupted. In which case it's no longer an issue as
470 * all our allocation from C now goes through a PA wrapper,
471 * but still, doesn't hurt.
473 * Yeah, but non-gencgc platforms that don't really wrap
474 * allocation in PA. MG - 2005-08-29 */
476 lispobj info_sap,context_sap = alloc_sap(context);
477 info_sap = alloc_sap(info);
478 /* Allow signals again. */
479 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
481 FSHOW_SIGNAL((stderr,"/calling Lisp-level handler\n"));
483 funcall3(handler.lisp,
489 FSHOW_SIGNAL((stderr,"/calling C-level handler\n"));
491 /* Allow signals again. */
492 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
494 (*handler.c)(signal, info, void_context);
497 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
501 undo_fake_foreign_function_call(context); /* block signals again */
504 FSHOW_SIGNAL((stderr,
505 "/returning from interrupt_handle_now(%d, info, context)\n",
509 /* This is called at the end of a critical section if the indications
510 * are that some signal was deferred during the section. Note that as
511 * far as C or the kernel is concerned we dealt with the signal
512 * already; we're just doing the Lisp-level processing now that we
516 run_deferred_handler(struct interrupt_data *data, void *v_context) {
517 /* The pending_handler may enable interrupts and then another
518 * interrupt may hit, overwrite interrupt_data, so reset the
519 * pending handler before calling it. Trust the handler to finish
520 * with the siginfo before enabling interrupts. */
521 void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
522 data->pending_handler=0;
523 (*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
527 maybe_defer_handler(void *handler, struct interrupt_data *data,
528 int signal, siginfo_t *info, os_context_t *context)
530 struct thread *thread=arch_os_get_current_thread();
532 check_blockables_blocked_or_lose();
534 if (SymbolValue(INTERRUPT_PENDING,thread) != NIL)
535 lose("interrupt already pending");
536 /* If interrupts are disabled then INTERRUPT_PENDING is set and
537 * not PSEDUO_ATOMIC_INTERRUPTED. This is important for a pseudo
538 * atomic section inside a WITHOUT-INTERRUPTS.
540 if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) {
541 store_signal_data_for_later(data,handler,signal,info,context);
542 SetSymbolValue(INTERRUPT_PENDING, T,thread);
543 FSHOW_SIGNAL((stderr,
544 "/maybe_defer_handler(%x,%d),thread=%lu: deferred\n",
545 (unsigned int)handler,signal,
546 (unsigned long)thread->os_thread));
549 /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't
550 * actually use its argument for anything on x86, so this branch
551 * may succeed even when context is null (gencgc alloc()) */
553 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
554 /* FIXME: this foreign_function_call_active test is dubious at
555 * best. If a foreign call is made in a pseudo atomic section
556 * (?) or more likely a pseudo atomic section is in a foreign
557 * call then an interrupt is executed immediately. Maybe it
558 * has to do with C code not maintaining pseudo atomic
559 * properly. MG - 2005-08-10 */
560 (!foreign_function_call_active) &&
562 arch_pseudo_atomic_atomic(context)) {
563 store_signal_data_for_later(data,handler,signal,info,context);
564 arch_set_pseudo_atomic_interrupted(context);
565 FSHOW_SIGNAL((stderr,
566 "/maybe_defer_handler(%x,%d),thread=%lu: deferred(PA)\n",
567 (unsigned int)handler,signal,
568 (unsigned long)thread->os_thread));
571 FSHOW_SIGNAL((stderr,
572 "/maybe_defer_handler(%x,%d),thread=%lu: not deferred\n",
573 (unsigned int)handler,signal,
574 (unsigned long)thread->os_thread));
579 store_signal_data_for_later (struct interrupt_data *data, void *handler,
581 siginfo_t *info, os_context_t *context)
583 if (data->pending_handler)
584 lose("tried to overwrite pending interrupt handler %x with %x\n",
585 data->pending_handler, handler);
587 lose("tried to defer null interrupt handler\n");
588 data->pending_handler = handler;
589 data->pending_signal = signal;
591 memcpy(&(data->pending_info), info, sizeof(siginfo_t));
593 /* the signal mask in the context (from before we were
594 * interrupted) is copied to be restored when
595 * run_deferred_handler happens. Then the usually-blocked
596 * signals are added to the mask in the context so that we are
597 * running with blocked signals when the handler returns */
598 sigcopyset(&(data->pending_mask),os_context_sigmask_addr(context));
599 sigaddset_deferrable(os_context_sigmask_addr(context));
604 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
606 os_context_t *context = arch_os_get_context(&void_context);
607 struct thread *thread=arch_os_get_current_thread();
608 struct interrupt_data *data=thread->interrupt_data;
609 #ifdef LISP_FEATURE_LINUX
610 os_restore_fp_control(context);
612 if(maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
614 interrupt_handle_now(signal, info, context);
615 #ifdef LISP_FEATURE_DARWIN
616 /* Work around G5 bug */
617 DARWIN_FIX_CONTEXT(context);
622 low_level_interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
624 os_context_t *context = (os_context_t*)void_context;
626 #ifdef LISP_FEATURE_LINUX
627 os_restore_fp_control(context);
629 check_blockables_blocked_or_lose();
630 check_interrupts_enabled_or_lose(context);
631 interrupt_low_level_handlers[signal](signal, info, void_context);
632 #ifdef LISP_FEATURE_DARWIN
633 /* Work around G5 bug */
634 DARWIN_FIX_CONTEXT(context);
639 low_level_maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
641 os_context_t *context = arch_os_get_context(&void_context);
642 struct thread *thread=arch_os_get_current_thread();
643 struct interrupt_data *data=thread->interrupt_data;
644 #ifdef LISP_FEATURE_LINUX
645 os_restore_fp_control(context);
647 if(maybe_defer_handler(low_level_interrupt_handle_now,data,
648 signal,info,context))
650 low_level_interrupt_handle_now(signal, info, context);
651 #ifdef LISP_FEATURE_DARWIN
652 /* Work around G5 bug */
653 DARWIN_FIX_CONTEXT(context);
657 #ifdef LISP_FEATURE_SB_THREAD
660 sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
662 os_context_t *context = arch_os_get_context(&void_context);
663 struct thread *thread=arch_os_get_current_thread();
667 if ((arch_pseudo_atomic_atomic(context) ||
668 SymbolValue(GC_INHIBIT,thread) != NIL)) {
669 SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
670 if (SymbolValue(GC_INHIBIT,thread) == NIL)
671 arch_set_pseudo_atomic_interrupted(context);
672 FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred\n",
675 /* need the context stored so it can have registers scavenged */
676 fake_foreign_function_call(context);
678 sigfillset(&ss); /* Block everything. */
679 thread_sigmask(SIG_BLOCK,&ss,0);
681 /* The GC can't tell if a thread is a zombie, so this would be a
682 * good time to let the kernel reap any of our children in that
683 * awful state, to stop them from being waited for indefinitely.
684 * Userland reaping is done later when GC is finished */
685 if(thread->state!=STATE_RUNNING) {
686 lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
687 fixnum_value(thread->state));
689 thread->state=STATE_SUSPENDED;
690 FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
692 sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
694 FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
695 if(thread->state!=STATE_RUNNING) {
696 lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
697 fixnum_value(thread->state));
700 undo_fake_foreign_function_call(context);
706 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
708 os_context_t *context = arch_os_get_context(&void_context);
709 interrupt_handle_now(signal, info, context);
710 #ifdef LISP_FEATURE_DARWIN
711 DARWIN_FIX_CONTEXT(context);
716 * stuff to detect and handle hitting the GC trigger
719 #ifndef LISP_FEATURE_GENCGC
720 /* since GENCGC has its own way to record trigger */
722 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
724 if (current_auto_gc_trigger == NULL)
727 void *badaddr=arch_get_bad_addr(signal,info,context);
728 return (badaddr >= (void *)current_auto_gc_trigger &&
729 badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE));
734 /* manipulate the signal context and stack such that when the handler
735 * returns, it will call function instead of whatever it was doing
739 #if (defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
740 int *context_eflags_addr(os_context_t *context);
743 extern lispobj call_into_lisp(lispobj fun, lispobj *args, int nargs);
744 extern void post_signal_tramp(void);
745 void arrange_return_to_lisp_function(os_context_t *context, lispobj function)
747 #if !(defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
748 void * fun=native_pointer(function);
749 void *code = &(((struct simple_fun *) fun)->code);
752 /* Build a stack frame showing `interrupted' so that the
753 * user's backtrace makes (as much) sense (as usual) */
755 /* FIXME: what about restoring fp state? */
756 /* FIXME: what about restoring errno? */
757 #ifdef LISP_FEATURE_X86
758 /* Suppose the existence of some function that saved all
759 * registers, called call_into_lisp, then restored GP registers and
760 * returned. It would look something like this:
768 pushl {address of function to call}
769 call 0x8058db0 <call_into_lisp>
776 * What we do here is set up the stack that call_into_lisp would
777 * expect to see if it had been called by this code, and frob the
778 * signal context so that signal return goes directly to call_into_lisp,
779 * and when that function (and the lisp function it invoked) returns,
780 * it returns to the second half of this imaginary function which
781 * restores all registers and returns to C
783 * For this to work, the latter part of the imaginary function
784 * must obviously exist in reality. That would be post_signal_tramp
787 u32 *sp=(u32 *)*os_context_register_addr(context,reg_ESP);
789 /* return address for call_into_lisp: */
790 *(sp-15) = (u32)post_signal_tramp;
791 *(sp-14) = function; /* args for call_into_lisp : function*/
792 *(sp-13) = 0; /* arg array */
793 *(sp-12) = 0; /* no. args */
794 /* this order matches that used in POPAD */
795 *(sp-11)=*os_context_register_addr(context,reg_EDI);
796 *(sp-10)=*os_context_register_addr(context,reg_ESI);
798 *(sp-9)=*os_context_register_addr(context,reg_ESP)-8;
799 /* POPAD ignores the value of ESP: */
801 *(sp-7)=*os_context_register_addr(context,reg_EBX);
803 *(sp-6)=*os_context_register_addr(context,reg_EDX);
804 *(sp-5)=*os_context_register_addr(context,reg_ECX);
805 *(sp-4)=*os_context_register_addr(context,reg_EAX);
806 *(sp-3)=*context_eflags_addr(context);
807 *(sp-2)=*os_context_register_addr(context,reg_EBP);
808 *(sp-1)=*os_context_pc_addr(context);
810 #elif defined(LISP_FEATURE_X86_64)
811 u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
812 /* return address for call_into_lisp: */
813 *(sp-18) = (u64)post_signal_tramp;
815 *(sp-17)=*os_context_register_addr(context,reg_R15);
816 *(sp-16)=*os_context_register_addr(context,reg_R14);
817 *(sp-15)=*os_context_register_addr(context,reg_R13);
818 *(sp-14)=*os_context_register_addr(context,reg_R12);
819 *(sp-13)=*os_context_register_addr(context,reg_R11);
820 *(sp-12)=*os_context_register_addr(context,reg_R10);
821 *(sp-11)=*os_context_register_addr(context,reg_R9);
822 *(sp-10)=*os_context_register_addr(context,reg_R8);
823 *(sp-9)=*os_context_register_addr(context,reg_RDI);
824 *(sp-8)=*os_context_register_addr(context,reg_RSI);
825 /* skip RBP and RSP */
826 *(sp-7)=*os_context_register_addr(context,reg_RBX);
827 *(sp-6)=*os_context_register_addr(context,reg_RDX);
828 *(sp-5)=*os_context_register_addr(context,reg_RCX);
829 *(sp-4)=*os_context_register_addr(context,reg_RAX);
830 *(sp-3)=*context_eflags_addr(context);
831 *(sp-2)=*os_context_register_addr(context,reg_RBP);
832 *(sp-1)=*os_context_pc_addr(context);
834 *os_context_register_addr(context,reg_RDI) =
835 (os_context_register_t)function; /* function */
836 *os_context_register_addr(context,reg_RSI) = 0; /* arg. array */
837 *os_context_register_addr(context,reg_RDX) = 0; /* no. args */
839 struct thread *th=arch_os_get_current_thread();
840 build_fake_control_stack_frames(th,context);
843 #ifdef LISP_FEATURE_X86
844 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
845 *os_context_register_addr(context,reg_ECX) = 0;
846 *os_context_register_addr(context,reg_EBP) = (os_context_register_t)(sp-2);
848 *os_context_register_addr(context,reg_UESP) =
849 (os_context_register_t)(sp-15);
851 *os_context_register_addr(context,reg_ESP) = (os_context_register_t)(sp-15);
853 #elif defined(LISP_FEATURE_X86_64)
854 *os_context_pc_addr(context) = (os_context_register_t)call_into_lisp;
855 *os_context_register_addr(context,reg_RCX) = 0;
856 *os_context_register_addr(context,reg_RBP) = (os_context_register_t)(sp-2);
857 *os_context_register_addr(context,reg_RSP) = (os_context_register_t)(sp-18);
859 /* this much of the calling convention is common to all
861 *os_context_pc_addr(context) = (os_context_register_t)(unsigned long)code;
862 *os_context_register_addr(context,reg_NARGS) = 0;
863 *os_context_register_addr(context,reg_LIP) =
864 (os_context_register_t)(unsigned long)code;
865 *os_context_register_addr(context,reg_CFP) =
866 (os_context_register_t)(unsigned long)current_control_frame_pointer;
868 #ifdef ARCH_HAS_NPC_REGISTER
869 *os_context_npc_addr(context) =
870 4 + *os_context_pc_addr(context);
872 #ifdef LISP_FEATURE_SPARC
873 *os_context_register_addr(context,reg_CODE) =
874 (os_context_register_t)(fun + FUN_POINTER_LOWTAG);
878 #ifdef LISP_FEATURE_SB_THREAD
879 void interrupt_thread_handler(int num, siginfo_t *info, void *v_context)
881 os_context_t *context = (os_context_t*)arch_os_get_context(&v_context);
882 /* The order of interrupt execution is peculiar. If thread A
883 * interrupts thread B with I1, I2 and B for some reason receives
884 * I1 when FUN2 is already on the list, then it is FUN2 that gets
885 * to run first. But when FUN2 is run SIG_INTERRUPT_THREAD is
886 * enabled again and I2 hits pretty soon in FUN2 and run
887 * FUN1. This is of course just one scenario, and the order of
888 * thread interrupt execution is undefined. */
889 struct thread *th=arch_os_get_current_thread();
892 if (th->state != STATE_RUNNING)
893 lose("interrupt_thread_handler: thread %lu in wrong state: %d\n",
894 th->os_thread,fixnum_value(th->state));
895 get_spinlock(&th->interrupt_fun_lock,(long)th);
896 c=((struct cons *)native_pointer(th->interrupt_fun));
898 th->interrupt_fun=c->cdr;
899 release_spinlock(&th->interrupt_fun_lock);
901 lose("interrupt_thread_handler: NIL function\n");
902 arrange_return_to_lisp_function(context,function);
907 /* KLUDGE: Theoretically the approach we use for undefined alien
908 * variables should work for functions as well, but on PPC/Darwin
909 * we get bus error at bogus addresses instead, hence this workaround,
910 * that has the added benefit of automatically discriminating between
911 * functions and variables.
913 void undefined_alien_function() {
914 funcall0(SymbolFunction(UNDEFINED_ALIEN_FUNCTION_ERROR));
917 boolean handle_guard_page_triggered(os_context_t *context,os_vm_address_t addr)
919 struct thread *th=arch_os_get_current_thread();
921 /* note the os_context hackery here. When the signal handler returns,
922 * it won't go back to what it was doing ... */
923 if(addr >= CONTROL_STACK_GUARD_PAGE(th) &&
924 addr < CONTROL_STACK_GUARD_PAGE(th) + os_vm_page_size) {
925 /* We hit the end of the control stack: disable guard page
926 * protection so the error handler has some headroom, protect the
927 * previous page so that we can catch returns from the guard page
929 protect_control_stack_guard_page(th,0);
930 protect_control_stack_return_guard_page(th,1);
932 arrange_return_to_lisp_function
933 (context, SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR));
936 else if(addr >= CONTROL_STACK_RETURN_GUARD_PAGE(th) &&
937 addr < CONTROL_STACK_RETURN_GUARD_PAGE(th) + os_vm_page_size) {
938 /* We're returning from the guard page: reprotect it, and
939 * unprotect this one. This works even if we somehow missed
940 * the return-guard-page, and hit it on our way to new
941 * exhaustion instead. */
942 protect_control_stack_guard_page(th,1);
943 protect_control_stack_return_guard_page(th,0);
946 else if (addr >= undefined_alien_address &&
947 addr < undefined_alien_address + os_vm_page_size) {
948 arrange_return_to_lisp_function
949 (context, SymbolFunction(UNDEFINED_ALIEN_VARIABLE_ERROR));
955 #ifndef LISP_FEATURE_GENCGC
956 /* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
957 * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check
958 * whether the signal was due to treading on the mprotect()ed zone -
959 * and if so, arrange for a GC to happen. */
960 extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
963 interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context)
965 os_context_t *context=(os_context_t *) void_context;
967 if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){
968 struct thread *thread=arch_os_get_current_thread();
969 clear_auto_gc_trigger();
970 /* Don't flood the system with interrupts if the need to gc is
971 * already noted. This can happen for example when SUB-GC
972 * allocates or after a gc triggered in a WITHOUT-GCING. */
973 if (SymbolValue(GC_PENDING,thread) == NIL) {
974 if (SymbolValue(GC_INHIBIT,thread) == NIL) {
975 if (arch_pseudo_atomic_atomic(context)) {
976 /* set things up so that GC happens when we finish
978 SetSymbolValue(GC_PENDING,T,thread);
979 arch_set_pseudo_atomic_interrupted(context);
981 interrupt_maybe_gc_int(signal,info,void_context);
984 SetSymbolValue(GC_PENDING,T,thread);
994 /* this is also used by gencgc, in alloc() */
996 interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
998 os_context_t *context=(os_context_t *) void_context;
999 struct thread *thread=arch_os_get_current_thread();
1001 fake_foreign_function_call(context);
1003 /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in
1004 * which case we will be running with no gc trigger barrier
1005 * thing for a while. But it shouldn't be long until the end
1008 * FIXME: It would be good to protect the end of dynamic space
1009 * and signal a storage condition from there.
1012 /* Restore the signal mask from the interrupted context before
1013 * calling into Lisp if interrupts are enabled. Why not always?
1015 * Suppose there is a WITHOUT-INTERRUPTS block far, far out. If an
1016 * interrupt hits while in SUB-GC, it is deferred and the
1017 * os_context_sigmask of that interrupt is set to block further
1018 * deferrable interrupts (until the first one is
1019 * handled). Unfortunately, that context refers to this place and
1020 * when we return from here the signals will not be blocked.
1022 * A kludgy alternative is to propagate the sigmask change to the
1025 if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL)
1026 thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
1027 #ifdef LISP_FEATURE_SB_THREAD
1030 sigaddset(&new,SIG_STOP_FOR_GC);
1031 thread_sigmask(SIG_UNBLOCK,&new,0);
1034 funcall0(SymbolFunction(SUB_GC));
1036 undo_fake_foreign_function_call(context);
1042 * noise to install handlers
1046 undoably_install_low_level_interrupt_handler (int signal,
1051 struct sigaction sa;
1053 if (0 > signal || signal >= NSIG) {
1054 lose("bad signal number %d", signal);
1057 if (sigismember(&deferrable_sigset,signal))
1058 sa.sa_sigaction = low_level_maybe_now_maybe_later;
1060 sa.sa_sigaction = handler;
1062 sigcopyset(&sa.sa_mask, &blockable_sigset);
1063 sa.sa_flags = SA_SIGINFO | SA_RESTART;
1064 #ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
1065 if((signal==SIG_MEMORY_FAULT)
1066 #ifdef SIG_INTERRUPT_THREAD
1067 || (signal==SIG_INTERRUPT_THREAD)
1070 sa.sa_flags |= SA_ONSTACK;
1073 sigaction(signal, &sa, NULL);
1074 interrupt_low_level_handlers[signal] =
1075 (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler);
1078 /* This is called from Lisp. */
1080 install_handler(int signal, void handler(int, siginfo_t*, void*))
1082 struct sigaction sa;
1084 union interrupt_handler oldhandler;
1086 FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal));
1089 sigaddset(&new, signal);
1090 thread_sigmask(SIG_BLOCK, &new, &old);
1092 FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%x\n",
1093 (unsigned int)interrupt_low_level_handlers[signal]));
1094 if (interrupt_low_level_handlers[signal]==0) {
1095 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
1096 ARE_SAME_HANDLER(handler, SIG_IGN)) {
1097 sa.sa_sigaction = handler;
1098 } else if (sigismember(&deferrable_sigset, signal)) {
1099 sa.sa_sigaction = maybe_now_maybe_later;
1101 sa.sa_sigaction = interrupt_handle_now_handler;
1104 sigcopyset(&sa.sa_mask, &blockable_sigset);
1105 sa.sa_flags = SA_SIGINFO | SA_RESTART;
1106 sigaction(signal, &sa, NULL);
1109 oldhandler = interrupt_handlers[signal];
1110 interrupt_handlers[signal].c = handler;
1112 thread_sigmask(SIG_SETMASK, &old, 0);
1114 FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal));
1116 return (unsigned long)oldhandler.lisp;
1123 SHOW("entering interrupt_init()");
1124 sigemptyset(&deferrable_sigset);
1125 sigemptyset(&blockable_sigset);
1126 sigaddset_deferrable(&deferrable_sigset);
1127 sigaddset_blockable(&blockable_sigset);
1129 /* Set up high level handler information. */
1130 for (i = 0; i < NSIG; i++) {
1131 interrupt_handlers[i].c =
1132 /* (The cast here blasts away the distinction between
1133 * SA_SIGACTION-style three-argument handlers and
1134 * signal(..)-style one-argument handlers, which is OK
1135 * because it works to call the 1-argument form where the
1136 * 3-argument form is expected.) */
1137 (void (*)(int, siginfo_t*, void*))SIG_DFL;
1140 SHOW("returning from interrupt_init()");