X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Finterrupt.c;h=4027b3dbf2fde10a9a3caf8bf7497de834b9100a;hb=3bb2fb5b9ecdeebecaded4ac6e5af0f653be8867;hp=aa944e44a2ece82f710d84c4a247f09455e22ad1;hpb=c9bb20c4b0d1f232ec83569d3456b3f3edc4aa1c;p=sbcl.git diff --git a/src/runtime/interrupt.c b/src/runtime/interrupt.c index aa944e4..4027b3d 100644 --- a/src/runtime/interrupt.c +++ b/src/runtime/interrupt.c @@ -14,13 +14,9 @@ */ #include - +#include +#include #include -#ifdef mach /* KLUDGE: #ifdef on lowercase symbols? Ick. -- WHN 19990904 */ -#ifdef mips -#include -#endif -#endif #include "runtime.h" #include "arch.h" @@ -35,6 +31,10 @@ #include "alloc.h" #include "dynbind.h" #include "interr.h" +#include "genesis/simple-fun.h" +#include "genesis/fdefn.h" +#include "genesis/symbol.h" +#include "genesis/static-symbols.h" void sigaddset_blockable(sigset_t *s) { @@ -44,6 +44,7 @@ void sigaddset_blockable(sigset_t *s) sigaddset(s, SIGPIPE); sigaddset(s, SIGALRM); sigaddset(s, SIGURG); + sigaddset(s, SIGFPE); sigaddset(s, SIGTSTP); sigaddset(s, SIGCHLD); sigaddset(s, SIGIO); @@ -73,17 +74,25 @@ os_context_t *lisp_interrupt_contexts[MAX_INTERRUPTS]; * In that case, the Lisp-level handler is stored in interrupt_handlers[..] * and interrupt_low_level_handlers[..] is cleared. * - * However, some signals need special handling, e.g. the SIGSEGV (for - * Linux) or SIGBUS (for 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 Lisp. For such signals, - * we still store any Lisp-level handler in interrupt_handlers[..], - * but for the outermost handle we use the value from - * interrupt_low_level_handlers[..], instead of the ordinary - * interrupt_handle_now(..) or interrupt_handle_later(..). + * However, some signals need special handling, e.g. + * + * 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 + * Lisp. For such signals, we still store any Lisp-level handler + * in interrupt_handlers[..], but for the outermost handle we use + * the value from interrupt_low_level_handlers[..], instead of the + * ordinary interrupt_handle_now(..) or interrupt_handle_later(..). * - * -- WHN 20000728 */ + * o the SIGTRAP (Linux/Alpha) which Lisp code uses to handle breakpoints, + * pseudo-atomic sections, and some classes of error (e.g. "function + * not defined"). This never goes anywhere near the Lisp handlers at all. + * See runtime/alpha-arch.c and code/signal.lisp + * + * - WHN 20000728, dan 20010128 */ + + void (*interrupt_low_level_handlers[NSIG]) (int, siginfo_t*, void*) = {0}; union interrupt_handler interrupt_handlers[NSIG]; @@ -94,45 +103,29 @@ static int pending_signal = 0; static siginfo_t pending_info; static sigset_t pending_mask; -static boolean maybe_gc_pending = 0; +boolean maybe_gc_pending = 0; /* * utility routines used by various signal handlers */ -void -fake_foreign_function_call(os_context_t *context) +void +build_fake_control_stack_frames(os_context_t *context) { - int context_index; -#ifndef __i386__ +#ifndef LISP_FEATURE_X86 + lispobj oldcont; -#endif - /* Get current Lisp state from context. */ -#ifdef reg_ALLOC - dynamic_space_free_pointer = - (lispobj *)(*os_context_register_addr(context, reg_ALLOC)); -#ifdef alpha - if ((long)dynamic_space_free_pointer & 1) { - lose("dead in fake_foreign_function_call, context = %x", context); - } -#endif -#endif -#ifdef reg_BSP - current_binding_stack_pointer = - (lispobj *)(*os_context_register_addr(context, reg_BSP)); -#endif + /* Build a fake stack frame or frames */ -#ifndef __i386__ - /* Build a fake stack frame. */ current_control_frame_pointer = (lispobj *)(*os_context_register_addr(context, reg_CSP)); if ((lispobj *)(*os_context_register_addr(context, reg_CFP)) == current_control_frame_pointer) { /* There is a small window during call where the callee's * frame isn't built yet. */ - if (LowtagOf(*os_context_register_addr(context, reg_CODE)) - == type_FunctionPointer) { + if (lowtag_of(*os_context_register_addr(context, reg_CODE)) + == FUN_POINTER_LOWTAG) { /* We have called, but not built the new frame, so * build it for them. */ current_control_frame_pointer[0] = @@ -149,9 +142,10 @@ fake_foreign_function_call(os_context_t *context) oldcont = (lispobj)(*os_context_register_addr(context, reg_OCFP)); } } - /* ### We can't tell whether we are still in the caller if it had - * to reg_ALLOCate the stack frame due to stack arguments. */ - /* ### Can anything strange happen during return? */ + /* We can't tell whether we are still in the caller if it had to + * allocate a stack frame due to stack arguments. */ + /* This observation provoked some past CMUCL maintainer to ask + * "Can anything strange happen during return?" */ else { /* normal case */ oldcont = (lispobj)(*os_context_register_addr(context, reg_CFP)); @@ -164,6 +158,29 @@ fake_foreign_function_call(os_context_t *context) current_control_frame_pointer[2] = (lispobj)(*os_context_register_addr(context, reg_CODE)); #endif +} + +void +fake_foreign_function_call(os_context_t *context) +{ + int context_index; + + /* Get current Lisp state from context. */ +#ifdef reg_ALLOC + dynamic_space_free_pointer = + (lispobj *)(*os_context_register_addr(context, reg_ALLOC)); +#ifdef alpha + if ((long)dynamic_space_free_pointer & 1) { + lose("dead in fake_foreign_function_call, context = %x", context); + } +#endif +#endif +#ifdef reg_BSP + current_binding_stack_pointer = + (lispobj *)(*os_context_register_addr(context, reg_BSP)); +#endif + + build_fake_control_stack_frames(context); /* Do dynamic binding of the active interrupt context index * and save the context in the context array. */ @@ -174,8 +191,7 @@ fake_foreign_function_call(os_context_t *context) * which do bare >> and << for fixnum_value and make_fixnum. */ if (context_index >= MAX_INTERRUPTS) { - lose("maximum interrupt nesting depth (%d) exceeded", - MAX_INTERRUPTS); + lose("maximum interrupt nesting depth (%d) exceeded", MAX_INTERRUPTS); } bind_variable(FREE_INTERRUPT_CONTEXT_INDEX, @@ -205,6 +221,7 @@ 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 @@ -254,6 +271,13 @@ interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context, } } +/* This function handles pending interrupts. Note that in C/kernel + * terms we dealt with the signal already; we just haven't decided + * whether to call a Lisp handler or do a GC or something like that. + * If it helps, you can think of pending_{signal,mask,info} as a + * one-element queue of signals that we have acknowledged but not + * processed */ + void interrupt_handle_pending(os_context_t *context) { @@ -280,10 +304,34 @@ interrupt_handle_pending(os_context_t *context) } } - /* FIXME: How come we unconditionally copy from pending_mask into - * the context, and then test whether pending_signal is set? If - * pending_signal wasn't set, how could pending_mask be valid? */ - memcpy(os_context_sigmask_addr(context), &pending_mask, sizeof(sigset_t)); + /* FIXME: This isn't very clear. It would be good to reverse + * engineer it and rewrite the code more clearly, or write a clear + * explanation of what's going on in the comments, or both. + * + * WHN's question 1a: How come we unconditionally copy from + * pending_mask into the context, and then test whether + * pending_signal is set? + * + * WHN's question 1b: If pending_signal wasn't set, how could + * pending_mask be valid? + * + * Dan Barlow's reply (sbcl-devel 2001-03-13): And the answer is - + * or appears to be - because interrupt_maybe_gc set it that way + * (look in the #ifndef __i386__ bit). We can't GC during a + * pseudo-atomic, so we set maybe_gc_pending=1 and + * arch_set_pseudo_atomic_interrupted(..) When we come out of + * pseudo_atomic we're marked as interrupted, so we call + * interrupt_handle_pending, which does the GC using the pending + * context (it needs a context so that it has registers to use as + * GC roots) then notices there's no actual interrupt handler to + * call, so doesn't. That's the second question [1b] answered, + * anyway. Why we still need to copy the pending_mask into the + * context given that we're now done with the context anyway, I + * couldn't say. */ +#if 0 + memcpy(os_context_sigmask_addr(context), &pending_mask, + 4 /* sizeof(sigset_t) */ ); +#endif sigemptyset(&pending_mask); if (pending_signal) { int signal = pending_signal; @@ -298,6 +346,15 @@ interrupt_handle_pending(os_context_t *context) * the two main signal handlers: * interrupt_handle_now(..) * maybe_now_maybe_later(..) + * + * to which we have added interrupt_handle_now_handler(..). Why? + * Well, mostly because the SPARC/Linux platform doesn't quite do + * signals the way we want them done. The third argument in the + * handler isn't filled in by the kernel properly, so we fix it up + * ourselves in the arch_os_get_context(..) function; however, we only + * want to do this when we first hit the handler, and not when + * interrupt_handle_now(..) is being called from some other handler + * (when the fixup will already have been done). -- CSR, 2002-07-23 */ void @@ -309,29 +366,18 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) #endif union interrupt_handler handler; - /* FIXME: The CMU CL we forked off of had this Linux-only - * operation here. Newer CMU CLs (e.g. 18c) have hairier - * Linux/i386-only logic here. SBCL seems to be more reliable - * without anything here. However, if we start supporting code - * which sets the rounding mode, then we may want to do something - * special to force the rounding mode back to some standard value - * here, so that ISRs can have a standard environment. (OTOH, if - * rounding modes are under user control, then perhaps we should - * leave this up to the user.) - * - * For now we just suppress this code completely (just like the - * parallel code in maybe_now_maybe_later). - * #ifdef __linux__ - * SET_FPU_CONTROL_WORD(context->__fpregs_mem.cw); - * #endif - */ - +#ifdef LISP_FEATURE_LINUX + /* Under Linux on some architectures, we appear to have to restore + the FPU control word from the context, as after the signal is + delivered we appear to have a null FPU control word. */ + os_restore_fp_control(context); +#endif handler = interrupt_handlers[signal]; if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) { return; } - + #ifndef __i386__ were_in_lisp = !foreign_function_call_active; if (were_in_lisp) @@ -341,7 +387,9 @@ 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)) { @@ -351,15 +399,14 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) * support decides to pass on it. */ lose("no handler for signal %d in interrupt_handle_now(..)", signal); - } else if (LowtagOf(handler.lisp) == type_FunctionPointer) { + } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) { /* Allocate the SAPs while the interrupts are still disabled. * (FIXME: Why? This is the way it was done in CMU CL, and it * even had the comment noting that this is the way it was * done, but no motivation..) */ - lispobj context_sap = alloc_sap(context); - lispobj info_sap = alloc_sap(info); - + lispobj info_sap,context_sap = alloc_sap(context); + info_sap = alloc_sap(info); /* Allow signals again. */ sigprocmask(SIG_SETMASK, os_context_sigmask_addr(context), 0); @@ -389,25 +436,26 @@ 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 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context) { - os_context_t *context = (os_context_t*)void_context; - - /* FIXME: See Debian cmucl 2.4.17, and mail from DTC on the CMU CL - * mailing list 23 Oct 1999, for changes in FPU handling at - * interrupt time which should be ported into SBCL. Also see the - * analogous logic at the head of interrupt_handle_now for - * more related FIXME stuff. - * - * For now, we just suppress this code completely. - * #ifdef __linux__ - * SET_FPU_CONTROL_WORD(context->__fpregs_mem.cw); - * #endif + os_context_t *context = arch_os_get_context(&void_context); + +#ifdef LISP_FEATURE_LINUX + os_restore_fp_control(context); +#endif + + /* see comments at top of code/signal.lisp for what's going on here + * with INTERRUPTS_ENABLED/INTERRUPT_HANDLE_NOW */ - if (SymbolValue(INTERRUPTS_ENABLED) == NIL) { /* FIXME: This code is exactly the same as the code in the @@ -419,7 +467,6 @@ maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context) os_context_sigmask_addr(context), sizeof(sigset_t)); sigaddset_blockable(os_context_sigmask_addr(context)); - SetSymbolValue(INTERRUPT_PENDING, T); } else if ( @@ -447,41 +494,115 @@ maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context) } } + +void +interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context) +{ + os_context_t *context = arch_os_get_context(&void_context); + interrupt_handle_now(signal, info, context); +} + /* * stuff to detect and handle hitting the GC trigger */ -#ifndef INTERNAL_GC_TRIGGER +#ifndef LISP_FEATURE_GENCGC +/* since GENCGC has its own way to record trigger */ static boolean gc_trigger_hit(int signal, siginfo_t *info, os_context_t *context) { if (current_auto_gc_trigger == NULL) return 0; else{ - lispobj *badaddr=(lispobj *)arch_get_bad_addr(signal, - info, - context); - - return (badaddr >= current_auto_gc_trigger && - badaddr < DYNAMIC_SPACE_START + DYNAMIC_SPACE_SIZE); + void *badaddr=arch_get_bad_addr(signal,info,context); + return (badaddr >= (void *)current_auto_gc_trigger && + badaddr <((void *)current_dynamic_space + DYNAMIC_SPACE_SIZE)); } } #endif -#ifndef __i386__ +/* and similarly for the control stack guard page */ + +boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr) +{ + /* note the os_context hackery here. When the signal handler returns, + * it won't go back to what it was doing ... */ + if(addr>=(void *)CONTROL_STACK_GUARD_PAGE && + addr<(void *)(CONTROL_STACK_GUARD_PAGE+os_vm_page_size)) { + void *fun; + void *code; + + /* we hit the end of the control stack. disable protection + * temporarily so the error handler has some headroom */ + protect_control_stack_guard_page(0); + + fun = (void *) + native_pointer((lispobj) SymbolFunction(CONTROL_STACK_EXHAUSTED_ERROR)); + code = &(((struct simple_fun *) fun)->code); + + /* Build a stack frame showing `interrupted' so that the + * user's backtrace makes (as much) sense (as usual) */ + build_fake_control_stack_frames(context); + /* signal handler will "return" to this error-causing function */ + *os_context_pc_addr(context) = code; +#ifdef LISP_FEATURE_X86 + *os_context_register_addr(context,reg_ECX) = 0; +#else + /* this much of the calling convention is common to all + non-x86 ports */ + *os_context_register_addr(context,reg_NARGS) = 0; + *os_context_register_addr(context,reg_LIP) = code; + *os_context_register_addr(context,reg_CFP) = + current_control_frame_pointer; +#endif +#ifdef ARCH_HAS_NPC_REGISTER + *os_context_npc_addr(context) = + 4 + *os_context_pc_addr(context); +#endif +#ifdef LISP_FEATURE_SPARC + /* Bletch. This is a feature of the SPARC calling convention, + which sadly I'm not going to go into in large detail here, + as I don't know it well enough. Suffice to say that if the + line + + (INST MOVE CODE-TN FUNCTION) + + in compiler/sparc/call.lisp is changed, then this bit can + probably go away. -- CSR, 2002-07-24 */ + *os_context_register_addr(context,reg_CODE) = + fun + FUN_POINTER_LOWTAG; +#endif + return 1; + } + else return 0; +} + +#ifndef LISP_FEATURE_X86 +/* 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, os_context_t *context) +interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context) { + os_context_t *context=(os_context_t *) void_context; + if (!foreign_function_call_active -#ifndef INTERNAL_GC_TRIGGER +#ifndef LISP_FEATURE_GENCGC + /* nb: GENCGC on non-x86? I really don't think so. This + * happens every time */ && gc_trigger_hit(signal, info, context) #endif ) { -#ifndef INTERNAL_GC_TRIGGER +#ifndef LISP_FEATURE_GENCGC clear_auto_gc_trigger(); #endif if (arch_pseudo_atomic_atomic(context)) { + /* don't GC during an atomic operation. Instead, copy the + * signal mask somewhere safe. interrupt_handle_pending + * will detect pending_signal==0 and know to do a GC with the + * signal context instead of calling a Lisp-level handler */ maybe_gc_pending = 1; if (pending_signal == 0) { /* FIXME: This copy-pending_mask-then-sigaddset_blockable @@ -495,11 +616,19 @@ interrupt_maybe_gc(int signal, siginfo_t *info, os_context_t *context) arch_set_pseudo_atomic_interrupted(context); } else { + lispobj *old_free_space=current_dynamic_space; fake_foreign_function_call(context); funcall0(SymbolFunction(MAYBE_GC)); undo_fake_foreign_function_call(context); - } - + if(current_dynamic_space==old_free_space) + /* MAYBE-GC (as the name suggest) might not. If it + * doesn't, it won't reset the GC trigger either, so we + * have to do it ourselves. Put it near the end of + * dynamic space so we're not running into it continually + */ + set_auto_gc_trigger(DYNAMIC_SPACE_SIZE + -(u32)os_vm_page_size); + } return 1; } else { return 0; @@ -511,22 +640,91 @@ interrupt_maybe_gc(int signal, siginfo_t *info, os_context_t *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 +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 -interrupt_install_low_level_handler (int signal, - void handler(int, siginfo_t*, 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; +#ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK + /* Signal handlers are run on the control stack, so if it is exhausted + * we had better use an alternate stack for whatever signal tells us + * we've exhausted it */ + if(signal==SIG_MEMORY_FAULT) { + stack_t sigstack; + sigstack.ss_sp=(void *) ALTERNATE_SIGNAL_STACK_START; + sigstack.ss_flags=0; + sigstack.ss_size = SIGSTKSZ; + sigaltstack(&sigstack,0); + sa.sa_flags|=SA_ONSTACK; + } +#endif + + /* 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); + } - 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. */ @@ -537,7 +735,7 @@ 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); @@ -546,7 +744,7 @@ 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) || @@ -555,7 +753,7 @@ install_handler(int signal, void handler(int, siginfo_t*, void*)) } else if (sigismember(&new, signal)) { sa.sa_sigaction = maybe_now_maybe_later; } else { - sa.sa_sigaction = interrupt_handle_now; + sa.sa_sigaction = interrupt_handle_now_handler; } sigemptyset(&sa.sa_mask); @@ -570,7 +768,7 @@ 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; } @@ -580,6 +778,12 @@ 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 @@ -589,4 +793,6 @@ interrupt_init(void) * 3-argument form is expected.) */ (void (*)(int, siginfo_t*, void*))SIG_DFL; } + + SHOW("returning from interrupt_init()"); }