1.0.5.49: interrupt & GC & PA handling
[sbcl.git] / src / runtime / interrupt.c
index 357a5b2..78bafeb 100644 (file)
 #include "genesis/simple-fun.h"
 #include "genesis/cons.h"
 
-
-
 static void run_deferred_handler(struct interrupt_data *data, void *v_context);
 #ifndef LISP_FEATURE_WIN32
 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);
 
 void
 sigaddset_deferrable(sigset_t *s)
@@ -123,9 +120,9 @@ static sigset_t blockable_sigset;
 #endif
 
 void
-check_blockables_blocked_or_lose()
+check_blockables_blocked_or_lose(void)
 {
-#ifndef LISP_FEATURE_WIN32
+#if !defined(LISP_FEATURE_WIN32)
     /* Get the current sigmask, by blocking the empty set. */
     sigset_t empty,current;
     int i;
@@ -138,17 +135,27 @@ check_blockables_blocked_or_lose()
 #endif
 }
 
+void
+unblock_gc_signals(void)
+{
+#ifdef LISP_FEATURE_SB_THREAD
+    sigset_t new;
+    sigemptyset(&new);
+#if defined(SIG_RESUME_FROM_GC)
+    sigaddset(&new,SIG_RESUME_FROM_GC);
+#endif
+    sigaddset(&new,SIG_STOP_FOR_GC);
+    thread_sigmask(SIG_UNBLOCK,&new,0);
+#endif
+}
+
 inline static void
 check_interrupts_enabled_or_lose(os_context_t *context)
 {
     struct thread *thread=arch_os_get_current_thread();
     if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL)
         lose("interrupts not enabled\n");
-    if (
-#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
-        (!foreign_function_call_active) &&
-#endif
-        arch_pseudo_atomic_atomic(context))
+    if (arch_pseudo_atomic_atomic(context))
         lose ("in pseudo atomic section\n");
 }
 
@@ -186,6 +193,14 @@ block_blockable_signals(void)
 #endif
 }
 
+void
+block_deferrable_signals(void)
+{
+#ifndef LISP_FEATURE_WIN32
+    thread_sigmask(SIG_BLOCK, &deferrable_sigset, 0);
+#endif
+}
+
 \f
 /*
  * utility routines used by various signal handlers
@@ -289,8 +304,9 @@ fake_foreign_function_call(os_context_t *context)
 
     thread->interrupt_contexts[context_index] = context;
 
-    /* no longer in Lisp now */
+#ifdef FOREIGN_FUNCTION_CALL_FLAG
     foreign_function_call_active = 1;
+#endif
 }
 
 /* blocks all blockable signals.  If you are calling from a signal handler,
@@ -303,8 +319,9 @@ undo_fake_foreign_function_call(os_context_t *context)
     /* Block all blockable signals. */
     block_blockable_signals();
 
-    /* going back into Lisp */
+#ifdef FOREIGN_FUNCTION_CALL_FLAG
     foreign_function_call_active = 0;
+#endif
 
     /* Undo dynamic binding of FREE_INTERRUPT_CONTEXT_INDEX */
     unbind(thread);
@@ -325,8 +342,7 @@ undo_fake_foreign_function_call(os_context_t *context)
 /* a handler for the signal caused by execution of a trap opcode
  * signalling an internal error */
 void
-interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
-                         boolean continuable)
+interrupt_internal_error(os_context_t *context, boolean continuable)
 {
     lispobj context_sap;
 
@@ -365,14 +381,35 @@ interrupt_internal_error(int signal, siginfo_t *info, os_context_t *context,
 void
 interrupt_handle_pending(os_context_t *context)
 {
+    /* There are three ways we can get here.  First, if an interrupt
+     * occurs within pseudo-atomic, it will be deferred, and we'll
+     * trap to here at the end of the pseudo-atomic block.  Second, if
+     * the GC (in alloc()) decides that a GC is required, it will set
+     * *GC-PENDING* and pseudo-atomic-interrupted, and alloc() is
+     * always called from within pseudo-atomic, and thus we end up
+     * here again.  Third, when calling GC-ON or at the end of a
+     * WITHOUT-GCING, MAYBE-HANDLE-PENDING-GC will trap to here if
+     * there is a pending GC. */
+
+    /* Win32 only needs to handle the GC cases (for now?) */
+
     struct thread *thread;
-    struct interrupt_data *data;
+
+    /* Punt if in PA section, marking it as interrupted. This can
+     * happenat least if we pick up a GC request while in a
+     * WITHOUT-GCING with an outer PA -- it is not immediately clear
+     * to me that this should/could ever happen, but better safe then
+     * sorry. --NS 2007-05-15 */
+    if (arch_pseudo_atomic_atomic(context)) {
+        arch_set_pseudo_atomic_interrupted(context);
+        return;
+    }
+
+    thread = arch_os_get_current_thread();
 
     FSHOW_SIGNAL((stderr, "/entering interrupt_handle_pending\n"));
 
     check_blockables_blocked_or_lose();
-    thread=arch_os_get_current_thread();
-    data=thread->interrupt_data;
 
     /* If pseudo_atomic_interrupted is set then the interrupt is going
      * to be handled now, ergo it's safe to clear it. */
@@ -381,10 +418,8 @@ interrupt_handle_pending(os_context_t *context)
     if (SymbolValue(GC_INHIBIT,thread)==NIL) {
 #ifdef LISP_FEATURE_SB_THREAD
         if (SymbolValue(STOP_FOR_GC_PENDING,thread) != NIL) {
-            /* another thread has already initiated a gc, this attempt
-             * might as well be cancelled */
-            SetSymbolValue(GC_PENDING,NIL,thread);
-            SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
+            /* STOP_FOR_GC_PENDING and GC_PENDING are cleared by
+             * the signal handler if it actually stops us. */
             sig_stop_for_gc_handler(SIG_STOP_FOR_GC,NULL,context);
         } else
 #endif
@@ -392,19 +427,16 @@ interrupt_handle_pending(os_context_t *context)
             /* GC_PENDING is cleared in SUB-GC, or if another thread
              * is doing a gc already we will get a SIG_STOP_FOR_GC and
              * that will clear it. */
-            interrupt_maybe_gc_int(0,NULL,context);
+            maybe_gc(context);
         }
         check_blockables_blocked_or_lose();
     }
 
+#ifndef LISP_FEATURE_WIN32
     /* we may be here only to do the gc stuff, if interrupts are
      * enabled run the pending handler */
-    if (!((SymbolValue(INTERRUPTS_ENABLED,thread) == NIL) ||
-          (
-#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
-           (!foreign_function_call_active) &&
-#endif
-           arch_pseudo_atomic_atomic(context)))) {
+    if (SymbolValue(INTERRUPTS_ENABLED,thread) != NIL) {
+        struct interrupt_data *data = thread->interrupt_data;
 
         /* There may be no pending handler, because it was only a gc
          * that had to be executed or because pseudo atomic triggered
@@ -418,9 +450,8 @@ interrupt_handle_pending(os_context_t *context)
              * to WITHOUT-INTERRUPTS, then INTERRUPT_PENDING is already
              * NIL, because maybe_defer_handler sets
              * PSEUDO_ATOMIC_INTERRUPTED only if interrupts are enabled.*/
-            SetSymbolValue(INTERRUPT_PENDING, NIL,thread);
+            SetSymbolValue(INTERRUPT_PENDING, NIL, thread);
 
-#ifndef LISP_FEATURE_WIN32
             /* 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.
@@ -429,12 +460,12 @@ interrupt_handle_pending(os_context_t *context)
             sigcopyset(os_context_sigmask_addr(context), &data->pending_mask);
 
             sigemptyset(&data->pending_mask);
-#endif
             /* This will break on sparc linux: the deferred handler really wants
              * to be called with a void_context */
             run_deferred_handler(data,(void *)context);
         }
     }
+#endif
 }
 \f
 /*
@@ -453,17 +484,15 @@ interrupt_handle_pending(os_context_t *context)
  */
 
 void
-interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
+interrupt_handle_now(int signal, siginfo_t *info, os_context_t *context)
 {
-    os_context_t *context = (os_context_t*)void_context;
-#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
+#ifdef FOREIGN_FUNCTION_CALL_FLAG
     boolean were_in_lisp;
 #endif
     union interrupt_handler handler;
 
     check_blockables_blocked_or_lose();
 
-
 #ifndef LISP_FEATURE_WIN32
     if (sigismember(&deferrable_sigset,signal))
         check_interrupts_enabled_or_lose(context);
@@ -476,14 +505,13 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
     os_restore_fp_control(context);
 #endif
 
-
     handler = interrupt_handlers[signal];
 
     if (ARE_SAME_HANDLER(handler.c, SIG_IGN)) {
         return;
     }
 
-#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
+#ifdef FOREIGN_FUNCTION_CALL_FLAG
     were_in_lisp = !foreign_function_call_active;
     if (were_in_lisp)
 #endif
@@ -548,11 +576,10 @@ interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
         /* Allow signals again. */
         thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
 #endif
-
-        (*handler.c)(signal, info, void_context);
+        (*handler.c)(signal, info, context);
     }
 
-#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
+#ifdef FOREIGN_FUNCTION_CALL_FLAG
     if (were_in_lisp)
 #endif
     {
@@ -576,7 +603,6 @@ run_deferred_handler(struct interrupt_data *data, void *v_context) {
      * pending handler before calling it. Trust the handler to finish
      * with the siginfo before enabling interrupts. */
     void (*pending_handler) (int, siginfo_t*, void*)=data->pending_handler;
-    os_context_t *context = arch_os_get_context(&v_context);
 
     data->pending_handler=0;
     (*pending_handler)(data->pending_signal,&(data->pending_info), v_context);
@@ -606,20 +632,10 @@ maybe_defer_handler(void *handler, struct interrupt_data *data,
                       (unsigned long)thread->os_thread));
         return 1;
     }
-    /* a slightly confusing test.  arch_pseudo_atomic_atomic() doesn't
+    /* 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 (
-#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
-        /* FIXME: this foreign_function_call_active test is dubious at
-         * best. If a foreign call is made in a pseudo atomic section
-         * (?) or more likely a pseudo atomic section is in a foreign
-         * call then an interrupt is executed immediately. Maybe it
-         * has to do with C code not maintaining pseudo atomic
-         * properly. MG - 2005-08-10 */
-        (!foreign_function_call_active) &&
-#endif
-        arch_pseudo_atomic_atomic(context)) {
+    if (arch_pseudo_atomic_atomic(context)) {
         store_signal_data_for_later(data,handler,signal,info,context);
         arch_set_pseudo_atomic_interrupted(context);
         FSHOW_SIGNAL((stderr,
@@ -667,64 +683,47 @@ static void
 maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
 {
     os_context_t *context = arch_os_get_context(&void_context);
-
-    struct thread *thread;
-    struct interrupt_data *data;
-
-    thread=arch_os_get_current_thread();
-    data=thread->interrupt_data;
+    struct thread *thread = arch_os_get_current_thread();
+    struct interrupt_data *data = thread->interrupt_data;
 
 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
     os_restore_fp_control(context);
 #endif
 
-    if(maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
-        return;
-    interrupt_handle_now(signal, info, context);
+    if(!maybe_defer_handler(interrupt_handle_now,data,signal,info,context))
+        interrupt_handle_now(signal, info, context);
+
 #ifdef LISP_FEATURE_DARWIN
-    /* Work around G5 bug */
     DARWIN_FIX_CONTEXT(context);
 #endif
 }
 
 static void
-low_level_interrupt_handle_now(int signal, siginfo_t *info, void *void_context)
+low_level_interrupt_handle_now(int signal, siginfo_t *info, os_context_t *context)
 {
-    os_context_t *context = (os_context_t*)void_context;
-
-#if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
-    os_restore_fp_control(context);
-#endif
-
+    /* No FP control fixage needed, caller has done that. */
     check_blockables_blocked_or_lose();
     check_interrupts_enabled_or_lose(context);
-    interrupt_low_level_handlers[signal](signal, info, void_context);
-#ifdef LISP_FEATURE_DARWIN
-    /* Work around G5 bug */
-    DARWIN_FIX_CONTEXT(context);
-#endif
+    interrupt_low_level_handlers[signal](signal, info, context);
+    /* No Darwin context fixage needed, caller does that. */
 }
 
 static void
 low_level_maybe_now_maybe_later(int signal, siginfo_t *info, void *void_context)
 {
     os_context_t *context = arch_os_get_context(&void_context);
-    struct thread *thread;
-    struct interrupt_data *data;
-
-    thread=arch_os_get_current_thread();
-    data=thread->interrupt_data;
+    struct thread *thread = arch_os_get_current_thread();
+    struct interrupt_data *data = thread->interrupt_data;
 
 #if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
     os_restore_fp_control(context);
 #endif
 
-    if(maybe_defer_handler(low_level_interrupt_handle_now,data,
-                           signal,info,context))
-        return;
-    low_level_interrupt_handle_now(signal, info, context);
+    if(!maybe_defer_handler(low_level_interrupt_handle_now,data,
+                            signal,info,context))
+        low_level_interrupt_handle_now(signal, info, context);
+
 #ifdef LISP_FEATURE_DARWIN
-    /* Work around G5 bug */
     DARWIN_FIX_CONTEXT(context);
 #endif
 }
@@ -740,53 +739,67 @@ sig_stop_for_gc_handler(int signal, siginfo_t *info, void *void_context)
     struct thread *thread=arch_os_get_current_thread();
     sigset_t ss;
 
-   if ((arch_pseudo_atomic_atomic(context) ||
-         SymbolValue(GC_INHIBIT,thread) != NIL)) {
+    if (arch_pseudo_atomic_atomic(context)) {
         SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
-        if (SymbolValue(GC_INHIBIT,thread) == NIL)
-            arch_set_pseudo_atomic_interrupted(context);
-        FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred\n",
+        arch_set_pseudo_atomic_interrupted(context);
+        FSHOW_SIGNAL((stderr,"thread=%lu sig_stop_for_gc deferred (PA)\n",
                       thread->os_thread));
-    } else {
-        /* need the context stored so it can have registers scavenged */
-        fake_foreign_function_call(context);
+        return;
+    }
+    else if (SymbolValue(GC_INHIBIT,thread) != NIL) {
+        SetSymbolValue(STOP_FOR_GC_PENDING,T,thread);
+        FSHOW_SIGNAL((stderr,
+                      "thread=%lu sig_stop_for_gc deferred (*GC-INHIBIT*)\n",
+                      thread->os_thread));
+        return;
+    }
 
-        sigfillset(&ss); /* Block everything. */
-        thread_sigmask(SIG_BLOCK,&ss,0);
+    /* Not PA and GC not inhibited -- we can stop now. */
 
-        if(thread->state!=STATE_RUNNING) {
-            lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
-                 fixnum_value(thread->state));
-        }
-        thread->state=STATE_SUSPENDED;
-        FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
+    /* need the context stored so it can have registers scavenged */
+    fake_foreign_function_call(context);
+
+    /* Block everything. */
+    sigfillset(&ss);
+    thread_sigmask(SIG_BLOCK,&ss,0);
+
+    /* Not pending anymore. */
+    SetSymbolValue(GC_PENDING,NIL,thread);
+    SetSymbolValue(STOP_FOR_GC_PENDING,NIL,thread);
+
+    if(thread->state!=STATE_RUNNING) {
+        lose("sig_stop_for_gc_handler: wrong thread state: %ld\n",
+             fixnum_value(thread->state));
+    }
+
+    thread->state=STATE_SUSPENDED;
+    FSHOW_SIGNAL((stderr,"thread=%lu suspended\n",thread->os_thread));
 
 #if defined(SIG_RESUME_FROM_GC)
-        sigemptyset(&ss); sigaddset(&ss,SIG_RESUME_FROM_GC);
+    sigemptyset(&ss); sigaddset(&ss,SIG_RESUME_FROM_GC);
 #else
-        sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
+    sigemptyset(&ss); sigaddset(&ss,SIG_STOP_FOR_GC);
 #endif
 
-        /* It is possible to get SIGCONT (and probably other
-         * non-blockable signals) here. */
+    /* It is possible to get SIGCONT (and probably other non-blockable
+     * signals) here. */
 #ifdef SIG_RESUME_FROM_GC
-        {
-            int sigret;
-            do { sigwait(&ss, &sigret); }
-            while (sigret != SIG_RESUME_FROM_GC);
-        }
+    {
+        int sigret;
+        do { sigwait(&ss, &sigret); }
+        while (sigret != SIG_RESUME_FROM_GC);
+    }
 #else
-        while (sigwaitinfo(&ss,0) != SIG_STOP_FOR_GC);
+    while (sigwaitinfo(&ss,0) != SIG_STOP_FOR_GC);
 #endif
 
-        FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
-        if(thread->state!=STATE_RUNNING) {
-            lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
-                 fixnum_value(thread->state));
-        }
-
-        undo_fake_foreign_function_call(context);
+    FSHOW_SIGNAL((stderr,"thread=%lu resumed\n",thread->os_thread));
+    if(thread->state!=STATE_RUNNING) {
+        lose("sig_stop_for_gc_handler: wrong thread state on wakeup: %ld\n",
+             fixnum_value(thread->state));
     }
+
+    undo_fake_foreign_function_call(context);
 }
 #endif
 
@@ -794,31 +807,15 @@ void
 interrupt_handle_now_handler(int signal, siginfo_t *info, void *void_context)
 {
     os_context_t *context = arch_os_get_context(&void_context);
+#if defined(LISP_FEATURE_LINUX) || defined(RESTORE_FP_CONTROL_FROM_CONTEXT)
+    os_restore_fp_control(context);
+#endif
     interrupt_handle_now(signal, info, context);
 #ifdef LISP_FEATURE_DARWIN
     DARWIN_FIX_CONTEXT(context);
 #endif
 }
 
-/*
- * stuff to detect and handle hitting the 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{
-        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
-
 /* manipulate the signal context and stack such that when the handler
  * returns, it will call function instead of whatever it was doing
  * previously
@@ -930,6 +927,7 @@ arrange_return_to_lisp_function(os_context_t *context, lispobj function)
 
 #elif defined(LISP_FEATURE_X86_64)
     u64 *sp=(u64 *)*os_context_register_addr(context,reg_RSP);
+
     /* return address for call_into_lisp: */
     *(sp-18) = (u64)post_signal_tramp;
 
@@ -1065,100 +1063,6 @@ handle_guard_page_triggered(os_context_t *context,os_vm_address_t addr)
     }
     else return 0;
 }
-
-#ifndef LISP_FEATURE_GENCGC
-/* This function gets called from the SIGSEGV (for e.g. Linux, NetBSD, &
- * 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. */
-extern unsigned long bytes_consed_between_gcs; /* gc-common.c */
-
-boolean
-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 && gc_trigger_hit(signal, info, context)){
-        struct thread *thread=arch_os_get_current_thread();
-        clear_auto_gc_trigger();
-        /* Don't flood the system with interrupts if the need to gc is
-         * already noted. This can happen for example when SUB-GC
-         * allocates or after a gc triggered in a WITHOUT-GCING. */
-        if (SymbolValue(GC_PENDING,thread) == NIL) {
-            if (SymbolValue(GC_INHIBIT,thread) == NIL) {
-                if (arch_pseudo_atomic_atomic(context)) {
-                    /* set things up so that GC happens when we finish
-                     * the PA section */
-                    SetSymbolValue(GC_PENDING,T,thread);
-                    arch_set_pseudo_atomic_interrupted(context);
-                } else {
-                    interrupt_maybe_gc_int(signal,info,void_context);
-                }
-            } else {
-                SetSymbolValue(GC_PENDING,T,thread);
-            }
-        }
-        return 1;
-    }
-    return 0;
-}
-
-#endif
-
-/* this is also used by gencgc, in alloc() */
-boolean
-interrupt_maybe_gc_int(int signal, siginfo_t *info, void *void_context)
-{
-    os_context_t *context=(os_context_t *) void_context;
-#ifndef LISP_FEATURE_WIN32
-    struct thread *thread=arch_os_get_current_thread();
-#endif
-
-    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.
-     *
-     * FIXME: It would be good to protect the end of dynamic space
-     * and signal a storage condition from there.
-     */
-
-    /* Restore the signal mask from the interrupted context before
-     * calling into Lisp if interrupts are enabled. Why not always?
-     *
-     * Suppose there is a WITHOUT-INTERRUPTS block far, far out. If an
-     * interrupt hits while in SUB-GC, it is deferred and the
-     * os_context_sigmask of that interrupt is set to block further
-     * deferrable interrupts (until the first one is
-     * handled). Unfortunately, that context refers to this place and
-     * when we return from here the signals will not be blocked.
-     *
-     * A kludgy alternative is to propagate the sigmask change to the
-     * outer context.
-     */
-#ifndef LISP_FEATURE_WIN32
-    if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL)
-        thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
-#ifdef LISP_FEATURE_SB_THREAD
-    else {
-        sigset_t new;
-        sigemptyset(&new);
-#if defined(SIG_RESUME_FROM_GC)
-        sigaddset(&new,SIG_RESUME_FROM_GC);
-#endif
-        sigaddset(&new,SIG_STOP_FOR_GC);
-        thread_sigmask(SIG_UNBLOCK,&new,0);
-    }
-#endif
-#endif
-    funcall0(SymbolFunction(SUB_GC));
-
-    undo_fake_foreign_function_call(context);
-    return 1;
-}
-
 \f
 /*
  * noise to install handlers
@@ -1189,7 +1093,7 @@ sigaction_nodefer_test_handler(int signal, siginfo_t *info, void *void_context)
     sigset_t empty, current;
     int i;
     sigemptyset(&empty);
-    sigprocmask(SIG_BLOCK, &empty, &current);
+    thread_sigmask(SIG_BLOCK, &empty, &current);
     /* There should be exactly two blocked signals: the two we added
      * to sa_mask when setting up the handler.  NetBSD doesn't block
      * the signal we're handling when SA_NODEFER is set; Linux before
@@ -1220,7 +1124,7 @@ see_if_sigaction_nodefer_works()
     {
         sigset_t empty;
         sigemptyset(&empty);
-        sigprocmask(SIG_SETMASK, &empty, 0);
+        thread_sigmask(SIG_SETMASK, &empty, 0);
     }
     kill(getpid(), SA_NODEFER_TEST_KILL_SIGNAL);
     while (sigaction_nodefer_works == -1);
@@ -1376,3 +1280,80 @@ interrupt_init()
     SHOW("returning from interrupt_init()");
 #endif
 }
+
+#ifndef LISP_FEATURE_WIN32
+int
+siginfo_code(siginfo_t *info)
+{
+    return info->si_code;
+}
+os_vm_address_t current_memory_fault_address;
+
+void
+lisp_memory_fault_error(os_context_t *context, os_vm_address_t addr)
+{
+   /* FIXME: This is lossy: if we get another memory fault (eg. from
+    * another thread) before lisp has read this, we the information.
+    * However, since this is mostly informative, we'll live with that for
+    * now -- some address is better then no address in this case.
+    */
+    current_memory_fault_address = addr;
+    arrange_return_to_lisp_function(context, SymbolFunction(MEMORY_FAULT_ERROR));
+}
+#endif
+
+void
+unhandled_trap_error(os_context_t *context)
+{
+    lispobj context_sap;
+    fake_foreign_function_call(context);
+    context_sap = alloc_sap(context);
+#ifndef LISP_FEATURE_WIN32
+    thread_sigmask(SIG_SETMASK, os_context_sigmask_addr(context), 0);
+#endif
+    funcall1(SymbolFunction(UNHANDLED_TRAP_ERROR), context_sap);
+    lose("UNHANDLED-TRAP-ERROR fell through");
+}
+
+/* Common logic far trapping instructions. How we actually handle each
+ * case is highly architecture dependent, but the overall shape is
+ * this. */
+void
+handle_trap(os_context_t *context, int trap)
+{
+    switch(trap) {
+    case trap_PendingInterrupt:
+        FSHOW((stderr, "/<trap pending interrupt>\n"));
+        arch_skip_instruction(context);
+        interrupt_handle_pending(context);
+        break;
+    case trap_Error:
+    case trap_Cerror:
+        FSHOW((stderr, "/<trap error/cerror %d>\n", trap));
+        interrupt_internal_error(context, trap==trap_Cerror);
+        break;
+    case trap_Breakpoint:
+        arch_handle_breakpoint(context);
+        break;
+    case trap_FunEndBreakpoint:
+        arch_handle_fun_end_breakpoint(context);
+        break;
+#ifdef trap_AfterBreakpoint
+    case trap_AfterBreakpoint:
+        arch_handle_after_breakpoint(context);
+        break;
+#endif
+#ifdef trap_SingleStepAround
+    case trap_SingleStepAround:
+    case trap_SingleStepBefore:
+        arch_handle_single_step_trap(context, trap);
+        break;
+#endif
+    case trap_Halt:
+        fake_foreign_function_call(context);
+        lose("%%PRIMITIVE HALT called; the party is over.\n");
+    default:
+        unhandled_trap_error(context);
+    }
+}
+