X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Finterrupt.c;h=7b4665242018ab46180d625bbb6dbd7c969be94e;hb=f7b3fe1bd86348bfd2a3c506e437084752142c83;hp=81c8e0944d5a814dd3d15074d7711e636aa37788;hpb=a8166c109a5ae1ebaa0204946c0f720e1acb700e;p=sbcl.git diff --git a/src/runtime/interrupt.c b/src/runtime/interrupt.c index 81c8e09..7b46652 100644 --- a/src/runtime/interrupt.c +++ b/src/runtime/interrupt.c @@ -13,6 +13,34 @@ * files for more information. */ + +/* As far as I can tell, what's going on here is: + * + * In the case of most signals, when Lisp asks us to handle the + * signal, the outermost handler (the one actually passed to UNIX) is + * either interrupt_handle_now(..) or maybe_now_maybe_later(..). + * 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. + * + * 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(..). + * + * 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 */ + + #include #include #include @@ -34,6 +62,27 @@ #include "genesis/fdefn.h" #include "genesis/simple-fun.h" +void run_deferred_handler(struct interrupt_data *data, void *v_context) ; +static void store_signal_data_for_later (struct interrupt_data *data, + void *handler, int signal, + siginfo_t *info, + os_context_t *context); +boolean interrupt_maybe_gc_int(int signal, siginfo_t *info, void *v_context); + +extern lispobj all_threads_lock; +extern int countdown_to_gc; + +/* + * This is a workaround for some slightly silly Linux/GNU Libc + * behaviour: glibc defines sigset_t to support 1024 signals, which is + * more than the kernel. This is usually not a problem, but becomes + * one when we want to save a signal mask from a ucontext, and restore + * it later into another ucontext: the ucontext is allocated on the + * stack by the kernel, so copying a libc-sized sigset_t into it will + * overflow and cause other data on the stack to be corrupted */ + +#define REAL_SIGSET_SIZE_BYTES ((NSIG/8)) + void sigaddset_blockable(sigset_t *s) { sigaddset(s, SIGHUP); @@ -53,6 +102,11 @@ void sigaddset_blockable(sigset_t *s) sigaddset(s, SIGWINCH); sigaddset(s, SIGUSR1); sigaddset(s, SIGUSR2); +#ifdef LISP_FEATURE_SB_THREAD + /* don't block STOP_FOR_GC, we need to be able to interrupt threads + * for GC purposes even when they are blocked on queues etc */ + sigaddset(s, SIG_INTERRUPT_THREAD); +#endif } /* When we catch an internal error, should we pass it back to Lisp to @@ -64,34 +118,6 @@ boolean internal_errors_enabled = 0; struct interrupt_data * global_interrupt_data; -/* As far as I can tell, what's going on here is: - * - * In the case of most signals, when Lisp asks us to handle the - * signal, the outermost handler (the one actually passed to UNIX) is - * either interrupt_handle_now(..) or maybe_now_maybe_later(..). - * 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. - * - * 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(..). - * - * 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 */ - - -boolean maybe_gc_pending = 0; /* * utility routines used by various signal handlers @@ -189,6 +215,10 @@ fake_foreign_function_call(os_context_t *context) foreign_function_call_active = 1; } +/* blocks all blockable signals. If you are calling from a signal handler, + * the usual signal mask will be restored from the context when the handler + * finishes. Otherwise, be careful */ + void undo_fake_foreign_function_call(os_context_t *context) { @@ -202,13 +232,7 @@ undo_fake_foreign_function_call(os_context_t *context) /* going back into Lisp */ foreign_function_call_active = 0; - /* Undo dynamic binding. */ - /* ### Do I really need to unbind_to_here()? */ - /* FIXME: Is this to undo the binding of - * 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 */ + /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */ unbind(thread); #ifdef reg_ALLOC @@ -258,81 +282,29 @@ 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) { struct thread *thread; struct interrupt_data *data; -#ifndef __i386__ - boolean were_in_lisp = !foreign_function_call_active; -#endif -#ifdef LISP_FEATURE_SB_THREAD - while(stop_the_world) kill(getpid(),SIGSTOP); -#endif thread=arch_os_get_current_thread(); data=thread->interrupt_data; SetSymbolValue(INTERRUPT_PENDING, NIL,thread); - if (maybe_gc_pending) { -#ifndef __i386__ - if (were_in_lisp) -#endif - { - fake_foreign_function_call(context); - } - funcall0(SymbolFunction(SUB_GC)); -#ifndef __i386__ - if (were_in_lisp) -#endif - { - undo_fake_foreign_function_call(context); - } - } + /* restore the saved signal mask from the original signal (the + * one that interrupted us during the critical section) into the + * os_context for the signal we're currently in the handler for. + * This should ensure that when we return from the handler the + * blocked signals are unblocked */ + + memcpy(os_context_sigmask_addr(context), &data->pending_mask, + REAL_SIGSET_SIZE_BYTES); - /* 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(&data->pending_mask); - if (data->pending_signal) { - int signal = data->pending_signal; - siginfo_t info; - memcpy(&info, &data->pending_info, sizeof(siginfo_t)); - data->pending_signal = 0; - interrupt_handle_now(signal, &info, context); - } + /* This will break on sparc linux: the deferred handler really wants + * to be called with a void_context */ + run_deferred_handler(data,(void *)context); } /* @@ -355,7 +327,7 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) { os_context_t *context = (os_context_t*)void_context; struct thread *thread=arch_os_get_current_thread(); -#ifndef __i386__ +#ifndef LISP_FEATURE_X86 boolean were_in_lisp; #endif union interrupt_handler handler; @@ -372,7 +344,7 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) return; } -#ifndef __i386__ +#ifndef LISP_FEATURE_X86 were_in_lisp = !foreign_function_call_active; if (were_in_lisp) #endif @@ -394,11 +366,18 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) lose("no handler for signal %d in interrupt_handle_now(..)", signal); } else if (lowtag_of(handler.lisp) == FUN_POINTER_LOWTAG) { + /* Once we've decided what to do about contexts in a + * return-elsewhere world (the original context will no longer + * be available; should we copy it or was nobody using it anyway?) + * then we should convert this to return-elsewhere */ + + /* CMUCL comment said "Allocate the SAPs while the interrupts + * are still disabled.". I (dan, 2003.08.21) assume this is + * because we're not in pseudoatomic and allocation shouldn't + * be interrupted. In which case it's no longer an issue as + * all our allocation from C now goes through a PA wrapper, + * but still, doesn't hurt */ - /* 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 info_sap,context_sap = alloc_sap(context); info_sap = alloc_sap(info); /* Allow signals again. */ @@ -424,7 +403,7 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) (*handler.c)(signal, info, void_context); } -#ifndef __i386__ +#ifndef LISP_FEATURE_X86 if (were_in_lisp) #endif { @@ -438,16 +417,72 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context) #endif } +/* This is called at the end of a critical section if the indications + * are that some signal was deferred during the section. Note that as + * far as C or the kernel is concerned we dealt with the signal + * already; we're just doing the Lisp-level processing now that we + * put off then */ + +void +run_deferred_handler(struct interrupt_data *data, void *v_context) { + fprintf(stderr,"Running deferred handler for %d, 0x%x\n", + data->pending_signal, data->pending_handler); + (*(data->pending_handler)) + (data->pending_signal,&(data->pending_info), v_context); +} + +boolean +maybe_defer_handler(void *handler, struct interrupt_data *data, + int signal, siginfo_t *info, os_context_t *context) +{ + struct thread *thread=arch_os_get_current_thread(); + if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) { + store_signal_data_for_later(data,handler,signal,info,context); + SetSymbolValue(INTERRUPT_PENDING, T,thread); + return 1; + } + /* a slightly confusing test. arch_pseudo_atomic_atomic() doesn't + * actually use its argument for anything on x86, so this branch + * may succeed even when context is null (gencgc alloc()) */ + if ( +#ifndef LISP_FEATURE_X86 + (!foreign_function_call_active) && +#endif + arch_pseudo_atomic_atomic(context)) { + store_signal_data_for_later(data,handler,signal,info,context); + arch_set_pseudo_atomic_interrupted(context); + return 1; + } + return 0; +} static void -store_signal_data_for_later (struct interrupt_data *data, int signal, +store_signal_data_for_later (struct interrupt_data *data, void *handler, + int signal, siginfo_t *info, os_context_t *context) { + data->pending_handler = handler; data->pending_signal = signal; - memcpy(&(data->pending_info), info, sizeof(siginfo_t)); - memcpy(&(data->pending_mask), - os_context_sigmask_addr(context), - sizeof(sigset_t)); - sigaddset_blockable(os_context_sigmask_addr(context)); + if(info) + memcpy(&(data->pending_info), info, sizeof(siginfo_t)); + if(context) { + /* the signal mask in the context (from before we were + * interrupted) is copied to be restored when + * run_deferred_handler happens. Then the usually-blocked + * signals are added to the mask in the context so that we are + * running with blocked signals when the handler returns */ + sigemptyset(&(data->pending_mask)); + memcpy(&(data->pending_mask), + os_context_sigmask_addr(context), + REAL_SIGSET_SIZE_BYTES); + sigaddset_blockable(os_context_sigmask_addr(context)); + } else { + /* this is also called from gencgc alloc(), in which case + * there has been no signal and is therefore no context. */ + sigset_t new; + sigemptyset(&new); + sigaddset_blockable(&new); + sigprocmask(SIG_BLOCK,&new,&(data->pending_mask)); + } } @@ -460,24 +495,38 @@ maybe_now_maybe_later(int signal, siginfo_t *info, void *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,thread) == NIL) { - store_signal_data_for_later(data,signal,info,context); - SetSymbolValue(INTERRUPT_PENDING, T,thread); - } else if ( -#ifndef __i386__ - (!foreign_function_call_active) && -#endif - arch_pseudo_atomic_atomic(context)) { - store_signal_data_for_later(data,signal,info,context); - arch_set_pseudo_atomic_interrupted(context); - } else { - interrupt_handle_now(signal, info, context); + if(maybe_defer_handler(interrupt_handle_now,data, + signal,info,context)) + return; + interrupt_handle_now(signal, info, context); +} + +void +sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context) +{ + os_context_t *context = arch_os_get_context(&void_context); + struct thread *thread=arch_os_get_current_thread(); + struct interrupt_data *data=thread->interrupt_data; + sigset_t block; + + if(maybe_defer_handler(sig_stop_for_gc_handler,data, + signal,info,context)){ + return; } + sigemptyset(&block); + sigaddset_blockable(&block); + sigprocmask(SIG_BLOCK, &block, 0); + + /* need the context stored so it can have registers scavenged */ + fake_foreign_function_call(context); + + get_spinlock(&all_threads_lock,thread->pid); + countdown_to_gc--; + release_spinlock(&all_threads_lock); + kill(getpid(),SIGSTOP); + + undo_fake_foreign_function_call(context); } - void interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context) @@ -576,16 +625,20 @@ void arrange_return_to_lisp_function(os_context_t *context, lispobj function) } #ifdef LISP_FEATURE_SB_THREAD -boolean handle_rt_signal(int num, siginfo_t *info, void *v_context) +void handle_rt_signal(int num, siginfo_t *info, void *v_context) { - struct - os_context_t *context = (os_context_t*)arch_os_get_context(&v_context); + os_context_t *context = (os_context_t*)arch_os_get_context(&v_context); + struct thread *th=arch_os_get_current_thread(); + struct interrupt_data *data= + th ? th->interrupt_data : global_interrupt_data; + if(maybe_defer_handler(handle_rt_signal,data,num,info,context)){ + return ; + } arrange_return_to_lisp_function(context,info->si_value.sival_int); } #endif -boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr) -{ +boolean handle_control_stack_guard_triggered(os_context_t *context,void *addr){ struct thread *th=arch_os_get_current_thread(); /* note the os_context hackery here. When the signal handler returns, * it won't go back to what it was doing ... */ @@ -619,67 +672,36 @@ interrupt_maybe_gc(int signal, siginfo_t *info, void *void_context) if(!foreign_function_call_active && gc_trigger_hit(signal, info, context)){ clear_auto_gc_trigger(); - - 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 (data->pending_signal == 0) { - /* FIXME: This copy-pending_mask-then-sigaddset_blockable - * idiom occurs over and over. It should be factored out - * into a function with a descriptive name. */ - memcpy(&(data->pending_mask), - os_context_sigmask_addr(context), - sizeof(sigset_t)); - sigaddset_blockable(os_context_sigmask_addr(context)); - } - arch_set_pseudo_atomic_interrupted(context); - } - else { - fake_foreign_function_call(context); - /* SUB-GC may return without GCing if *GC-INHIBIT* is set, - * in which case we will be running with no gc trigger - * barrier thing for a while. But it shouldn't be long - * until the end of WITHOUT-GCING. */ - funcall0(SymbolFunction(SUB_GC)); - undo_fake_foreign_function_call(context); - } + if(!maybe_defer_handler + (interrupt_maybe_gc_int,data,signal,info,void_context)) + interrupt_maybe_gc_int(signal,info,void_context); return 1; - } else { - return 0; } + return 0; } + #endif + +/* this is also used by from gencgc.c alloc() */ +boolean +interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context) +{ + os_context_t *context=(os_context_t *) void_context; + fake_foreign_function_call(context); + /* SUB-GC may return without GCing if *GC-INHIBIT* is set, in + * which case we will be running with no gc trigger barrier + * thing for a while. But it shouldn't be long until the end + * of WITHOUT-GCING. */ + funcall0(SymbolFunction(SUB_GC)); + undo_fake_foreign_function_call(context); + return 1; +} + /* * noise to install handlers */ -/* SBCL used to have code to restore signal handlers on exit, which - * has been removed from the threaded version until we decide: exit of - * _what_ ? */ - -/* SBCL comment: 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. */ - -/* I'm not sure (a) whether this is a real concern, (b) how it helps - anyway */ - -void -uninstall_low_level_interrupt_handlers_atexit(void) -{ -} - void undoably_install_low_level_interrupt_handler (int signal, void handler(int,