X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Finterrupt.c;h=c516822562a94f19980216173a49506ec8a30a5d;hb=872175cd9cb5b4966a36d4bd92421cc407a0355b;hp=bc6ed906948c14a0b65bd3fa225f3bbd2fd9861b;hpb=dfa55a883f94470267b626dae77ce7e7dfac3df6;p=sbcl.git diff --git a/src/runtime/interrupt.c b/src/runtime/interrupt.c index bc6ed90..c516822 100644 --- a/src/runtime/interrupt.c +++ b/src/runtime/interrupt.c @@ -14,6 +14,7 @@ */ #include +#include #include #ifdef mach /* KLUDGE: #ifdef on lowercase symbols? Ick. -- WHN 19990904 */ @@ -75,7 +76,7 @@ os_context_t *lisp_interrupt_contexts[MAX_INTERRUPTS]; * * However, some signals need special handling, e.g. * - * o the SIGSEGV (for Linux) or SIGBUS (for FreeBSD) used by the + * o the SIGSEGV (for e.g. Linux) or SIGBUS (for e.g. FreeBSD) used by the * garbage collector to detect violations of write protection, * because some cases of such signals (e.g. GC-related violations of * write protection) are handled at C level and never passed on to @@ -213,6 +214,7 @@ undo_fake_foreign_function_call(os_context_t *context) * FREE_INTERRUPT_CONTEXT_INDEX? If so, we should say so. And * perhaps yes, unbind_to_here() really would be clearer and less * fragile.. */ + /* dan (2001.08.10) thinks the above supposition is probably correct */ unbind(); #ifdef reg_ALLOC @@ -242,7 +244,6 @@ interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context, if (internal_errors_enabled) { SHOW("in interrupt_internal_error"); -#define QSHOW 1 #if QSHOW /* Display some rudimentary debugging information about the * error, so that even if the Lisp error handler gets badly @@ -378,7 +379,9 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) } #ifdef QSHOW_SIGNALS - FSHOW((stderr, "in interrupt_handle_now(%d, info, context)\n", signal)); + FSHOW((stderr, + "/entering interrupt_handle_now(%d, info, context)\n", + signal)); #endif if (ARE_SAME_HANDLER(handler.c, SIG_DFL)) { @@ -425,6 +428,12 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) { undo_fake_foreign_function_call(context); } + +#ifdef QSHOW_SIGNALS + FSHOW((stderr, + "/returning from interrupt_handle_now(%d, info, context)\n", + signal)); +#endif } static void @@ -506,10 +515,10 @@ gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context) #endif #ifndef __i386__ -/* This function gets called from the SIGSEGV (Linux) or SIGBUS (BSD) - * handler. Here we check whether the signal was due to treading on - * the mprotect()ed zone - and if so, arrange for a GC to happen. - */ +/* This function gets called from the SIGSEGV (for e.g. Linux or + * OpenBSD) or SIGBUS (for e.g. FreeBSD) handler. Here we check + * whether the signal was due to treading on the mprotect()ed zone - + * and if so, arrange for a GC to happen. */ boolean interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context) { @@ -558,22 +567,78 @@ interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context) * noise to install handlers */ -/* Install a special low-level handler for signal; or if handler is - * SIG_DFL, remove any special handling for signal. */ +/* + * what low-level signal handlers looked like before + * undoably_install_low_level_interrupt_handler() got involved + */ +struct low_level_signal_handler_state { + int was_modified; + void (*handler)(int, siginfo_t*, void*); +} old_low_level_signal_handler_states[NSIG]; + void -interrupt_install_low_level_handler (int signal, - void handler(int, siginfo_t*, void*)) +uninstall_low_level_interrupt_handlers_atexit(void) +{ + int signal; + for (signal = 0; signal < NSIG; ++signal) { + struct low_level_signal_handler_state + *old_low_level_signal_handler_state = + old_low_level_signal_handler_states + signal; + if (old_low_level_signal_handler_state->was_modified) { + struct sigaction sa; + sa.sa_sigaction = old_low_level_signal_handler_state->handler; + sigemptyset(&sa.sa_mask); + sa.sa_flags = SA_SIGINFO | SA_RESTART; + sigaction(signal, &sa, NULL); + } + } +} + +/* Undoably install a special low-level handler for signal; or if + * handler is SIG_DFL, remove any special handling for signal. + * + * The "undoably" aspect is because we also arrange with atexit() for + * the handler to be restored to its old value. This is for tidiness: + * it shouldn't matter much ordinarily, but it does remove a window + * where e.g. memory fault signals (SIGSEGV or SIGBUS, which in + * ordinary operation of SBCL are sent to the generational garbage + * collector, then possibly onward to Lisp code) or SIGINT (which is + * ordinarily passed to Lisp code) could otherwise be handled + * bizarrely/brokenly because the Lisp code would try to deal with + * them using machinery (like stream output buffers) which has already + * been dismantled. */ +void +undoably_install_low_level_interrupt_handler (int signal, + void handler(int, + siginfo_t*, + void*)) { struct sigaction sa; + struct low_level_signal_handler_state *old_low_level_signal_handler_state = + old_low_level_signal_handler_states + signal; + + if (0 > signal || signal >= NSIG) { + lose("bad signal number %d", signal); + } sa.sa_sigaction = handler; sigemptyset(&sa.sa_mask); sigaddset_blockable(&sa.sa_mask); sa.sa_flags = SA_SIGINFO | SA_RESTART; - sigaction(signal, &sa, NULL); + /* In the case of interrupt handlers which are modified more than + * once, we only save the original unmodified copy. */ + if (!old_low_level_signal_handler_state->was_modified) { + struct sigaction *old_handler = + (struct sigaction*) &old_low_level_signal_handler_state->handler; + old_low_level_signal_handler_state->was_modified = 1; + sigaction(signal, &sa, old_handler); + } else { + sigaction(signal, &sa, NULL); + } + interrupt_low_level_handlers[signal] = - (ARE_SAME_HANDLER(handler,SIG_DFL) ? 0 : handler); + (ARE_SAME_HANDLER(handler, SIG_DFL) ? 0 : handler); } /* This is called from Lisp. */ @@ -584,7 +649,7 @@ install_handler(int signal, void handler(int, siginfo_t*, void*)) sigset_t old, new; union interrupt_handler oldhandler; - FSHOW((stderr, "entering POSIX install_handler(%d, ..)\n", signal)); + FSHOW((stderr, "/entering POSIX install_handler(%d, ..)\n", signal)); sigemptyset(&new); sigaddset(&new, signal); @@ -593,7 +658,7 @@ install_handler(int signal, void handler(int, siginfo_t*, void*)) sigemptyset(&new); sigaddset_blockable(&new); - FSHOW((stderr, "interrupt_low_level_handlers[signal]=%d\n", + FSHOW((stderr, "/interrupt_low_level_handlers[signal]=%d\n", interrupt_low_level_handlers[signal])); if (interrupt_low_level_handlers[signal]==0) { if (ARE_SAME_HANDLER(handler, SIG_DFL) || @@ -617,7 +682,7 @@ install_handler(int signal, void handler(int, siginfo_t*, void*)) sigprocmask(SIG_SETMASK, &old, 0); - FSHOW((stderr, "leaving POSIX install_handler(%d, ..)\n", signal)); + FSHOW((stderr, "/leaving POSIX install_handler(%d, ..)\n", signal)); return (unsigned long)oldhandler.lisp; } @@ -627,6 +692,12 @@ interrupt_init(void) { int i; + SHOW("entering interrupt_init()"); + + /* Set up for recovery from any installed low-level handlers. */ + atexit(&uninstall_low_level_interrupt_handlers_atexit); + + /* Set up high level handler information. */ for (i = 0; i < NSIG; i++) { interrupt_handlers[i].c = /* (The cast here blasts away the distinction between @@ -636,4 +707,6 @@ interrupt_init(void) * 3-argument form is expected.) */ (void (*)(int, siginfo_t*, void*))SIG_DFL; } + + SHOW("returning from interrupt_init()"); }