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.
23 #ifdef mach /* KLUDGE: #ifdef on lowercase symbols? Ick. -- WHN 19990904 */
33 #include "interrupt.h"
43 void sigaddset_blockable(sigset_t *s)
47 sigaddset(s, SIGQUIT);
48 sigaddset(s, SIGPIPE);
49 sigaddset(s, SIGALRM);
51 sigaddset(s, SIGTSTP);
52 sigaddset(s, SIGCHLD);
54 sigaddset(s, SIGXCPU);
55 sigaddset(s, SIGXFSZ);
56 sigaddset(s, SIGVTALRM);
57 sigaddset(s, SIGPROF);
58 sigaddset(s, SIGWINCH);
59 sigaddset(s, SIGUSR1);
60 sigaddset(s, SIGUSR2);
63 /* When we catch an internal error, should we pass it back to Lisp to
64 * be handled in a high-level way? (Early in cold init, the answer is
65 * 'no', because Lisp is still too brain-dead to handle anything.
66 * After sufficient initialization has been completed, the answer
68 boolean internal_errors_enabled = 0;
70 os_context_t *lisp_interrupt_contexts[MAX_INTERRUPTS];
72 /* As far as I can tell, what's going on here is:
74 * In the case of most signals, when Lisp asks us to handle the
75 * signal, the outermost handler (the one actually passed to UNIX) is
76 * either interrupt_handle_now(..) or interrupt_handle_later(..).
77 * In that case, the Lisp-level handler is stored in interrupt_handlers[..]
78 * and interrupt_low_level_handlers[..] is cleared.
80 * However, some signals need special handling, e.g. the SIGSEGV (for
81 * Linux) or SIGBUS (for FreeBSD) used by the garbage collector to
82 * detect violations of write protection, because some cases of such
83 * signals are handled at C level and never passed on to Lisp. For
84 * such signals, we still store any Lisp-level handler in
85 * interrupt_handlers[..], but for the outermost handle we use the
86 * value from interrupt_low_level_handlers[..], instead of the
87 * ordinary interrupt_handle_now(..) or interrupt_handle_later(..).
90 void (*interrupt_low_level_handlers[NSIG]) (int, siginfo_t*, void*) = {0};
91 union interrupt_handler interrupt_handlers[NSIG];
93 /* signal number, siginfo_t, and old mask information for pending signal
95 * pending_signal=0 when there is no pending signal. */
96 static int pending_signal = 0;
97 static siginfo_t pending_info;
98 static sigset_t pending_mask;
100 static boolean maybe_gc_pending = 0;
103 * utility routines used by various signal handlers
107 fake_foreign_function_call(os_context_t *context)
114 /* Get current Lisp state from context. */
116 current_dynamic_space_free_pointer =
117 (lispobj *)(*os_context_register_addr(context, reg_ALLOC));
119 if ((long)current_dynamic_space_free_pointer & 1) {
120 lose("dead in fake_foreign_function_call, context = %x", context);
125 current_binding_stack_pointer =
126 (lispobj *)(*os_context_register_addr(context, reg_BSP));
130 /* Build a fake stack frame. */
131 current_control_frame_pointer =
132 (lispobj *)(*os_context_register_addr(context, reg_CSP));
133 if ((lispobj *)(*os_context_register_addr(context, reg_CFP))
134 == current_control_frame_pointer) {
135 /* There is a small window during call where the callee's
136 * frame isn't built yet. */
137 if (LowtagOf(*os_context_register_addr(context, reg_CODE))
138 == type_FunctionPointer) {
139 /* We have called, but not built the new frame, so
140 * build it for them. */
141 current_control_frame_pointer[0] =
142 *os_context_register_addr(context, reg_OCFP);
143 current_control_frame_pointer[1] =
144 *os_context_register_addr(context, reg_LRA);
145 current_control_frame_pointer += 8;
146 /* Build our frame on top of it. */
147 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
150 /* We haven't yet called, build our frame as if the
151 * partial frame wasn't there. */
152 oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP));
155 /* ### We can't tell if we are still in the caller if it had to
156 * reg_ALLOCate the stack frame due to stack arguments. */
157 /* ### Can anything strange happen during return? */
160 oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP));
162 current_control_stack_pointer = current_control_frame_pointer + 8;
164 current_control_frame_pointer[0] = oldcont;
165 current_control_frame_pointer[1] = NIL;
166 current_control_frame_pointer[2] =
167 (lispobj)(*os_context_register_addr(context, reg_CODE));
170 /* Do dynamic binding of the active interrupt context index
171 * and save the context in the context array. */
172 context_index = SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX)>>2;
173 /* FIXME: Ick! Why use abstract "make_fixnum" in some places if
174 * you're going to convert from fixnum by bare >>2 in other
175 * places? Use fixnum_value(..) here, and look for other places
176 * which do bare >> and << for fixnum_value and make_fixnum. */
178 if (context_index >= MAX_INTERRUPTS) {
179 lose("maximum interrupt nesting depth (%d) exceeded",
183 bind_variable(FREE_INTERRUPT_CONTEXT_INDEX,
184 make_fixnum(context_index + 1));
186 lisp_interrupt_contexts[context_index] = context;
188 /* no longer in Lisp now */
189 foreign_function_call_active = 1;
193 undo_fake_foreign_function_call(os_context_t *context)
195 /* Block all blockable signals. */
198 sigaddset_blockable(&block);
199 sigprocmask(SIG_BLOCK, &block, 0);
201 /* going back into Lisp */
202 foreign_function_call_active = 0;
204 /* Undo dynamic binding. */
205 /* ### Do I really need to unbind_to_here()? */
206 /* FIXME: Is this to undo the binding of
207 * FREE_INTERRUPT_CONTEXT_INDEX? If so, we should say so. And
208 * perhaps yes, unbind_to_here() really would be clearer and less
213 /* Put the dynamic space free pointer back into the context. */
214 *os_context_register_addr(context, reg_ALLOC) =
215 (unsigned long) current_dynamic_space_free_pointer;
219 /* a handler for the signal caused by execution of a trap opcode
220 * signalling an internal error */
222 interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
227 fake_foreign_function_call(context);
229 /* Allocate the SAP object while the interrupts are still
231 if (internal_errors_enabled) {
232 context_sap = alloc_sap(context);
235 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
237 if (internal_errors_enabled) {
238 SHOW("in interrupt_internal_error");
240 /* Display some rudimentary debugging information about the
241 * error, so that even if the Lisp error handler gets badly
242 * confused, we have a chance to determine what's going on. */
243 describe_internal_error(context);
245 funcall2(SymbolFunction(INTERNAL_ERROR), context_sap,
246 continuable ? T : NIL);
248 describe_internal_error(context);
249 /* There's no good way to recover from an internal error
250 * before the Lisp error handling mechanism is set up. */
251 lose("internal error too early in init, can't recover");
253 undo_fake_foreign_function_call(context);
255 arch_skip_instruction(context);
260 interrupt_handle_pending(os_context_t *context)
262 boolean were_in_lisp = !foreign_function_call_active;
264 SetSymbolValue(INTERRUPT_PENDING, NIL);
266 if (maybe_gc_pending) {
267 maybe_gc_pending = 0;
272 fake_foreign_function_call(context);
274 funcall0(SymbolFunction(MAYBE_GC));
279 undo_fake_foreign_function_call(context);
283 /* FIXME: How come we unconditionally copy from pending_mask into
284 * the context, and then test whether pending_signal is set? If
285 * pending_signal wasn't set, how could pending_mask be valid? */
286 memcpy(os_context_sigmask_addr(context), &pending_mask, sizeof(sigset_t));
287 sigemptyset(&pending_mask);
288 if (pending_signal) {
289 int signal = pending_signal;
291 memcpy(&info, &pending_info, sizeof(siginfo_t));
293 interrupt_handle_now(signal, &info, context);
298 * the two main signal handlers:
299 * interrupt_handle_now(..)
300 * maybe_now_maybe_later(..)
304 interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
306 os_context_t *context = (os_context_t*)void_context;
308 union interrupt_handler handler;
311 SET_FPU_CONTROL_WORD(context->__fpregs_mem.cw);
314 handler = interrupt_handlers[signal];
316 if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
320 were_in_lisp = !foreign_function_call_active;
325 fake_foreign_function_call(context);
329 FSHOW((stderr, "in interrupt_handle_now(%d, info, context)\n", signal));
332 if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) {
334 /* This can happen if someone tries to ignore or default one
335 * of the signals we need for runtime support, and the runtime
336 * support decides to pass on it. */
337 lose("no handler for signal %d in interrupt_handle_now(..)", signal);
339 } else if (LowtagOf(handler.lisp) == type_FunctionPointer) {
341 /* Allocate the SAPs while the interrupts are still disabled.
342 * (FIXME: Why? This is the way it was done in CMU CL, and it
343 * even had the comment noting that this is the way it was
344 * done, but no motivation..) */
345 lispobj context_sap = alloc_sap(context);
346 lispobj info_sap = alloc_sap(info);
348 /* Allow signals again. */
349 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
352 SHOW("calling Lisp-level handler");
355 funcall3(handler.lisp,
362 SHOW("calling C-level handler");
365 /* Allow signals again. */
366 sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
368 (*handler.c)(signal, info, void_context);
375 undo_fake_foreign_function_call(context);
380 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
382 os_context_t *context = (os_context_t*)void_context;
384 /* FIXME: See Debian cmucl 2.4.17, and mail from DTC on the CMU CL
385 * mailing list 23 Oct 1999, for changes in FPU handling at
386 * interrupt time which should be ported into SBCL.
388 * (Is this related to the way that it seems that if we do decide
389 * to handle the interrupt later, we've now screwed up the FPU
392 SET_FPU_CONTROL_WORD(context->__fpregs_mem.cw);
395 if (SymbolValue(INTERRUPTS_ENABLED) == NIL) {
397 /* FIXME: This code is exactly the same as the code in the
398 * other leg of the if(..), and should be factored out into
399 * a shared function. */
400 pending_signal = signal;
401 memcpy(&pending_info, info, sizeof(siginfo_t));
402 memcpy(&pending_mask,
403 os_context_sigmask_addr(context),
405 sigaddset_blockable(os_context_sigmask_addr(context));
407 SetSymbolValue(INTERRUPT_PENDING, T);
411 (!foreign_function_call_active) &&
413 arch_pseudo_atomic_atomic(context)) {
415 /* FIXME: It would probably be good to replace these bare
416 * memcpy(..) calls with calls to cpy_siginfo_t and
417 * cpy_sigset_t, so that we only have to get the sizeof
418 * expressions right in one place, and after that static type
419 * checking takes over. */
420 pending_signal = signal;
421 memcpy(&pending_info, info, sizeof(siginfo_t));
422 memcpy(&pending_mask,
423 os_context_sigmask_addr(context),
425 sigaddset_blockable(os_context_sigmask_addr(context));
427 arch_set_pseudo_atomic_interrupted(context);
430 interrupt_handle_now(signal, info, context);
435 * stuff to detect and handle hitting the GC trigger
438 #ifndef INTERNAL_GC_TRIGGER
440 gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context)
442 if (current_auto_gc_trigger == NULL)
445 lispobj *badaddr=(lispobj *)arch_get_bad_addr(signal,
449 return (badaddr >= current_auto_gc_trigger &&
450 badaddr < current_dynamic_space + DYNAMIC_SPACE_SIZE);
457 interrupt_maybe_gc(int signal, siginfo_t *info, os_context_t *context)
459 if (!foreign_function_call_active
460 #ifndef INTERNAL_GC_TRIGGER
461 && gc_trigger_hit(signal, info, context)
464 #ifndef INTERNAL_GC_TRIGGER
465 clear_auto_gc_trigger();
468 if (arch_pseudo_atomic_atomic(context)) {
469 maybe_gc_pending = 1;
470 if (pending_signal == 0) {
471 /* FIXME: This copy-pending_mask-then-sigaddset_blockable
472 * idiom occurs over and over. It should be factored out
473 * into a function with a descriptive name. */
474 memcpy(&pending_mask,
475 os_context_sigmask_addr(context),
477 sigaddset_blockable(os_context_sigmask_addr(context));
479 arch_set_pseudo_atomic_interrupted(context);
482 fake_foreign_function_call(context);
483 funcall0(SymbolFunction(MAYBE_GC));
484 undo_fake_foreign_function_call(context);
495 * noise to install handlers
498 /* Install a special low-level handler for signal; or if handler is
499 * SIG_DFL, remove any special handling for signal. */
501 interrupt_install_low_level_handler (int signal,
502 void handler(int, siginfo_t*, void*))
506 sa.sa_sigaction = handler;
507 sigemptyset(&sa.sa_mask);
508 sigaddset_blockable(&sa.sa_mask);
509 sa.sa_flags = SA_SIGINFO | SA_RESTART;
511 sigaction(signal, &sa, NULL);
512 interrupt_low_level_handlers[signal] =
513 (ARE_SAME_HANDLER(handler,SIG_DFL) ? 0 : handler);
516 /* This is called from Lisp. */
518 install_handler(int signal, void handler(int, siginfo_t*, void*))
522 union interrupt_handler oldhandler;
524 FSHOW((stderr, "entering POSIX install_handler(%d, ..)\n", signal));
527 sigaddset(&new, signal);
528 sigprocmask(SIG_BLOCK, &new, &old);
531 sigaddset_blockable(&new);
533 FSHOW((stderr, "interrupt_low_level_handlers[signal]=%d\n",
534 interrupt_low_level_handlers[signal]));
535 if (interrupt_low_level_handlers[signal]==0) {
536 if (ARE_SAME_HANDLER(handler, SIG_DFL) ||
537 ARE_SAME_HANDLER(handler, SIG_IGN)) {
538 sa.sa_sigaction = handler;
539 } else if (sigismember(&new, signal)) {
540 sa.sa_sigaction = maybe_now_maybe_later;
542 sa.sa_sigaction = interrupt_handle_now;
545 sigemptyset(&sa.sa_mask);
546 sigaddset_blockable(&sa.sa_mask);
547 sa.sa_flags = SA_SIGINFO | SA_RESTART;
549 sigaction(signal, &sa, NULL);
552 oldhandler = interrupt_handlers[signal];
553 interrupt_handlers[signal].c = handler;
555 sigprocmask(SIG_SETMASK, &old, 0);
557 FSHOW((stderr, "leaving POSIX install_handler(%d, ..)\n", signal));
559 return (unsigned long)oldhandler.lisp;
567 for (i = 0; i < NSIG; i++) {
568 interrupt_handlers[i].c =
569 /* (The cast here blasts away the distinction between
570 * SA_SIGACTION-style three-argument handlers and
571 * signal(..)-style one-argument handlers, which is OK
572 * because it works to call the 1-argument form where the
573 * 3-argument form is expected.) */
574 (void (*)(int, siginfo_t*, void*))SIG_DFL;