scavenge(&function_ptr->name, 1);
scavenge(&function_ptr->arglist, 1);
scavenge(&function_ptr->type, 1);
- scavenge(&function_ptr->xrefs, 1);
+ scavenge(&function_ptr->info, 1);
}
return n_words;
boolean
maybe_gc(os_context_t *context)
{
-#ifndef LISP_FEATURE_WIN32
+ lispobj gc_happened;
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
* outer context.
*/
#ifndef LISP_FEATURE_WIN32
- if(SymbolValue(INTERRUPTS_ENABLED,thread)!=NIL) {
+ check_gc_signals_unblocked_or_lose(os_context_sigmask_addr(context));
+ unblock_gc_signals(0, 0);
+#endif
+ FSHOW((stderr, "/maybe_gc: calling SUB_GC\n"));
+ /* FIXME: Nothing must go wrong during GC else we end up running
+ * the debugger, error handlers, and user code in general in a
+ * potentially unsafe place. Running out of the control stack or
+ * the heap in SUB-GC are ways to lose. Of course, deferrables
+ * cannot be unblocked because there may be a pending handler, or
+ * we may even be in a WITHOUT-INTERRUPTS. */
+ gc_happened = funcall0(StaticSymbolFunction(SUB_GC));
+ FSHOW((stderr, "/maybe_gc: gc_happened=%s\n",
+ (gc_happened == NIL) ? "NIL" : "T"));
+ if ((gc_happened != NIL) &&
+ /* See if interrupts are enabled or it's possible to enable
+ * them. POST-GC has a similar check, but we don't want to
+ * unlock deferrables in that case and get a pending interrupt
+ * here. */
+ ((SymbolValue(INTERRUPTS_ENABLED,thread) != NIL) ||
+ (SymbolValue(ALLOW_WITH_INTERRUPTS,thread) != NIL))) {
+#ifndef LISP_FEATURE_WIN32
sigset_t *context_sigmask = os_context_sigmask_addr(context);
-#ifdef LISP_FEATURE_SB_THREAD
- /* What if the context we'd like to restore has GC signals
- * blocked? Just skip the GC: we can't set GC_PENDING, because
- * that would block the next attempt, and we don't know when
- * we'd next check for it -- and it's hard to be sure that
- * unblocking would be safe.
- *
- * FIXME: This is not actually much better: we may already have
- * GC_PENDING set, and presumably our caller assumes that we will
- * clear it. Perhaps we should, even though we don't actually GC? */
- if (sigismember(context_sigmask,SIG_STOP_FOR_GC)) {
- undo_fake_foreign_function_call(context);
- return 1;
+ if (!deferrables_blocked_p(context_sigmask)) {
+ thread_sigmask(SIG_SETMASK, context_sigmask, 0);
+ check_gc_signals_unblocked_or_lose(0);
+#endif
+ FSHOW((stderr, "/maybe_gc: calling POST_GC\n"));
+ funcall0(StaticSymbolFunction(POST_GC));
+#ifndef LISP_FEATURE_WIN32
+ } else {
+ FSHOW((stderr, "/maybe_gc: punting on POST_GC due to blockage\n"));
}
#endif
- thread_sigmask(SIG_SETMASK, context_sigmask, 0);
}
- else
- unblock_gc_signals();
-#endif
- /* SIG_STOP_FOR_GC needs to be enabled before we can call lisp:
- * otherwise two threads racing here may deadlock: the other will
- * wait on the GC lock, and the other cannot stop the first one... */
- funcall0(StaticSymbolFunction(SUB_GC));
undo_fake_foreign_function_call(context);
- return 1;
+ FSHOW((stderr, "/maybe_gc: returning\n"));
+ return (gc_happened != NIL);
+}
+
+#define BYTES_ZERO_BEFORE_END (1<<12)
+
+/* There used to be a similar function called SCRUB-CONTROL-STACK in
+ * Lisp and another called zero_stack() in cheneygc.c, but since it's
+ * shorter to express in, and more often called from C, I keep only
+ * the C one after fixing it. -- MG 2009-03-25 */
+
+/* Zero the unused portion of the control stack so that old objects
+ * are not kept alive because of uninitialized stack variables.
+ *
+ * "To summarize the problem, since not all allocated stack frame
+ * slots are guaranteed to be written by the time you call an another
+ * function or GC, there may be garbage pointers retained in your dead
+ * stack locations. The stack scrubbing only affects the part of the
+ * stack from the SP to the end of the allocated stack." - ram, on
+ * cmucl-imp, Tue, 25 Sep 2001
+ *
+ * So, as an (admittedly lame) workaround, from time to time we call
+ * scrub-control-stack to zero out all the unused portion. This is
+ * supposed to happen when the stack is mostly empty, so that we have
+ * a chance of clearing more of it: callers are currently (2002.07.18)
+ * REPL, SUB-GC and sig_stop_for_gc_handler. */
+
+/* Take care not to tread on the guard page and the hard guard page as
+ * it would be unkind to sig_stop_for_gc_handler. Touching the return
+ * guard page is not dangerous. For this to work the guard page must
+ * be zeroed when protected. */
+
+/* FIXME: I think there is no guarantee that once
+ * BYTES_ZERO_BEFORE_END bytes are zero the rest are also zero. This
+ * may be what the "lame" adjective in the above comment is for. In
+ * this case, exact gc may lose badly. */
+void
+scrub_control_stack(void)
+{
+ struct thread *th = arch_os_get_current_thread();
+ os_vm_address_t guard_page_address = CONTROL_STACK_GUARD_PAGE(th);
+ os_vm_address_t hard_guard_page_address = CONTROL_STACK_HARD_GUARD_PAGE(th);
+ lispobj *sp;
+#ifdef LISP_FEATURE_C_STACK_IS_CONTROL_STACK
+ sp = (lispobj *)&sp - 1;
+#else
+ sp = current_control_stack_pointer;
+#endif
+ scrub:
+ if ((((os_vm_address_t)sp < (hard_guard_page_address + os_vm_page_size)) &&
+ ((os_vm_address_t)sp >= hard_guard_page_address)) ||
+ (((os_vm_address_t)sp < (guard_page_address + os_vm_page_size)) &&
+ ((os_vm_address_t)sp >= guard_page_address) &&
+ (th->control_stack_guard_page_protected != NIL)))
+ return;
+#ifdef LISP_FEATURE_STACK_GROWS_DOWNWARD_NOT_UPWARD
+ do {
+ *sp = 0;
+ } while (((unsigned long)sp--) & (BYTES_ZERO_BEFORE_END - 1));
+ if ((os_vm_address_t)sp < (hard_guard_page_address + os_vm_page_size))
+ return;
+ do {
+ if (*sp)
+ goto scrub;
+ } while (((unsigned long)sp--) & (BYTES_ZERO_BEFORE_END - 1));
+#else
+ do {
+ *sp = 0;
+ } while (((unsigned long)++sp) & (BYTES_ZERO_BEFORE_END - 1));
+ if ((os_vm_address_t)sp >= hard_guard_page_address)
+ return;
+ do {
+ if (*sp)
+ goto scrub;
+ } while (((unsigned long)++sp) & (BYTES_ZERO_BEFORE_END - 1));
+#endif
}
projects / sbcl.git / blobdiff