X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fruntime%2Fgc-common.c;h=96ac8df05e719371dc08bd214cc1a4c4ec5e3a91;hb=dd54f9e004a0a83d1328e94648f48dcc27e0be5b;hp=67b0fb3d3806eb8052f9fb1122bda6187a7ceda2;hpb=c4cf289fd86cb3008935ecd04312865a36e28976;p=sbcl.git

diff --git a/src/runtime/gc-common.c b/src/runtime/gc-common.c
old mode 100644
new mode 100755
index 67b0fb3..96ac8df
--- a/src/runtime/gc-common.c
+++ b/src/runtime/gc-common.c
@@ -52,8 +52,8 @@
 #endif
 #endif
 
-size_t dynamic_space_size = DEFAULT_DYNAMIC_SPACE_SIZE;
-size_t thread_control_stack_size = DEFAULT_CONTROL_STACK_SIZE;
+os_vm_size_t dynamic_space_size = DEFAULT_DYNAMIC_SPACE_SIZE;
+os_vm_size_t thread_control_stack_size = DEFAULT_CONTROL_STACK_SIZE;
 
 inline static boolean
 forwarding_pointer_p(lispobj *pointer) {
@@ -90,33 +90,13 @@ lispobj (*transother[256])(lispobj object);
 long (*sizetab[256])(lispobj *where);
 struct weak_pointer *weak_pointers;
 
-unsigned long bytes_consed_between_gcs = 12*1024*1024;
-
+os_vm_size_t bytes_consed_between_gcs = 12*1024*1024;
 
 /*
  * copying objects
  */
-static
-lispobj
-gc_general_copy_object(lispobj object, long nwords, int page_type_flag)
-{
-    int tag;
-    lispobj *new;
-
-    gc_assert(is_lisp_pointer(object));
-    gc_assert(from_space_p(object));
-    gc_assert((nwords & 0x01) == 0);
-
-    /* Get tag of object. */
-    tag = lowtag_of(object);
-
-    /* Allocate space. */
-    new = gc_general_alloc(nwords*N_WORD_BYTES, page_type_flag, ALLOC_QUICK);
 
-    /* Copy the object. */
-    memcpy(new,native_pointer(object),nwords*N_WORD_BYTES);
-    return make_lispobj(new,tag);
-}
+/* gc_general_copy_object is inline from gc-internal.h */
 
 /* to copy a boxed object */
 lispobj
@@ -1916,7 +1896,7 @@ size_lose(lispobj *where)
 void
 gc_init_tables(void)
 {
-    unsigned long i;
+    unsigned long i, j;
 
     /* Set default value in all slots of scavenge table.  FIXME
      * replace this gnarly sizeof with something based on
@@ -1931,11 +1911,14 @@ gc_init_tables(void)
      */
 
     for (i = 0; i < (1<<(N_WIDETAG_BITS-N_LOWTAG_BITS)); i++) {
-        scavtab[EVEN_FIXNUM_LOWTAG|(i<<N_LOWTAG_BITS)] = scav_immediate;
+        for (j = 0; j < (1<<N_LOWTAG_BITS); j++) {
+            if (fixnump(j)) {
+                scavtab[j|(i<<N_LOWTAG_BITS)] = scav_immediate;
+            }
+        }
         scavtab[FUN_POINTER_LOWTAG|(i<<N_LOWTAG_BITS)] = scav_fun_pointer;
         /* skipping OTHER_IMMEDIATE_0_LOWTAG */
         scavtab[LIST_POINTER_LOWTAG|(i<<N_LOWTAG_BITS)] = scav_list_pointer;
-        scavtab[ODD_FIXNUM_LOWTAG|(i<<N_LOWTAG_BITS)] = scav_immediate;
         scavtab[INSTANCE_POINTER_LOWTAG|(i<<N_LOWTAG_BITS)] =
             scav_instance_pointer;
         /* skipping OTHER_IMMEDIATE_1_LOWTAG */
@@ -1984,16 +1967,16 @@ gc_init_tables(void)
         scav_vector_unsigned_byte_16;
     scavtab[SIMPLE_ARRAY_UNSIGNED_BYTE_16_WIDETAG] =
         scav_vector_unsigned_byte_16;
-#ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_29_WIDETAG
-    scavtab[SIMPLE_ARRAY_UNSIGNED_BYTE_29_WIDETAG] =
+#if (N_WORD_BITS == 32)
+    scavtab[SIMPLE_ARRAY_UNSIGNED_FIXNUM_WIDETAG] =
         scav_vector_unsigned_byte_32;
 #endif
     scavtab[SIMPLE_ARRAY_UNSIGNED_BYTE_31_WIDETAG] =
         scav_vector_unsigned_byte_32;
     scavtab[SIMPLE_ARRAY_UNSIGNED_BYTE_32_WIDETAG] =
         scav_vector_unsigned_byte_32;
-#ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_60_WIDETAG
-    scavtab[SIMPLE_ARRAY_UNSIGNED_BYTE_60_WIDETAG] =
+#if (N_WORD_BITS == 64)
+    scavtab[SIMPLE_ARRAY_UNSIGNED_FIXNUM_WIDETAG] =
         scav_vector_unsigned_byte_64;
 #endif
 #ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_63_WIDETAG
@@ -2011,16 +1994,16 @@ gc_init_tables(void)
     scavtab[SIMPLE_ARRAY_SIGNED_BYTE_16_WIDETAG] =
         scav_vector_unsigned_byte_16;
 #endif
-#ifdef SIMPLE_ARRAY_SIGNED_BYTE_30_WIDETAG
-    scavtab[SIMPLE_ARRAY_SIGNED_BYTE_30_WIDETAG] =
+#if (N_WORD_BITS == 32)
+    scavtab[SIMPLE_ARRAY_FIXNUM_WIDETAG] =
         scav_vector_unsigned_byte_32;
 #endif
 #ifdef SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG
     scavtab[SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG] =
         scav_vector_unsigned_byte_32;
 #endif
-#ifdef SIMPLE_ARRAY_SIGNED_BYTE_61_WIDETAG
-    scavtab[SIMPLE_ARRAY_SIGNED_BYTE_61_WIDETAG] =
+#if (N_WORD_BITS == 64)
+    scavtab[SIMPLE_ARRAY_FIXNUM_WIDETAG] =
         scav_vector_unsigned_byte_64;
 #endif
 #ifdef SIMPLE_ARRAY_SIGNED_BYTE_64_WIDETAG
@@ -2122,16 +2105,16 @@ gc_init_tables(void)
         trans_vector_unsigned_byte_16;
     transother[SIMPLE_ARRAY_UNSIGNED_BYTE_16_WIDETAG] =
         trans_vector_unsigned_byte_16;
-#ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_29_WIDETAG
-    transother[SIMPLE_ARRAY_UNSIGNED_BYTE_29_WIDETAG] =
+#if (N_WORD_BITS == 32)
+    transother[SIMPLE_ARRAY_UNSIGNED_FIXNUM_WIDETAG] =
         trans_vector_unsigned_byte_32;
 #endif
     transother[SIMPLE_ARRAY_UNSIGNED_BYTE_31_WIDETAG] =
         trans_vector_unsigned_byte_32;
     transother[SIMPLE_ARRAY_UNSIGNED_BYTE_32_WIDETAG] =
         trans_vector_unsigned_byte_32;
-#ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_60_WIDETAG
-    transother[SIMPLE_ARRAY_UNSIGNED_BYTE_60_WIDETAG] =
+#if (N_WORD_BITS == 64)
+    transother[SIMPLE_ARRAY_UNSIGNED_FIXNUM_WIDETAG] =
         trans_vector_unsigned_byte_64;
 #endif
 #ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_63_WIDETAG
@@ -2150,16 +2133,16 @@ gc_init_tables(void)
     transother[SIMPLE_ARRAY_SIGNED_BYTE_16_WIDETAG] =
         trans_vector_unsigned_byte_16;
 #endif
-#ifdef SIMPLE_ARRAY_SIGNED_BYTE_30_WIDETAG
-    transother[SIMPLE_ARRAY_SIGNED_BYTE_30_WIDETAG] =
+#if (N_WORD_BITS == 32)
+    transother[SIMPLE_ARRAY_FIXNUM_WIDETAG] =
         trans_vector_unsigned_byte_32;
 #endif
 #ifdef SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG
     transother[SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG] =
         trans_vector_unsigned_byte_32;
 #endif
-#ifdef SIMPLE_ARRAY_SIGNED_BYTE_61_WIDETAG
-    transother[SIMPLE_ARRAY_SIGNED_BYTE_61_WIDETAG] =
+#if (N_WORD_BITS == 64)
+    transother[SIMPLE_ARRAY_FIXNUM_WIDETAG] =
         trans_vector_unsigned_byte_64;
 #endif
 #ifdef SIMPLE_ARRAY_SIGNED_BYTE_64_WIDETAG
@@ -2213,11 +2196,14 @@ gc_init_tables(void)
     for (i = 0; i < ((sizeof sizetab)/(sizeof sizetab[0])); i++)
         sizetab[i] = size_lose;
     for (i = 0; i < (1<<(N_WIDETAG_BITS-N_LOWTAG_BITS)); i++) {
-        sizetab[EVEN_FIXNUM_LOWTAG|(i<<N_LOWTAG_BITS)] = size_immediate;
+        for (j = 0; j < (1<<N_LOWTAG_BITS); j++) {
+            if (fixnump(j)) {
+                sizetab[j|(i<<N_LOWTAG_BITS)] = size_immediate;
+            }
+        }
         sizetab[FUN_POINTER_LOWTAG|(i<<N_LOWTAG_BITS)] = size_pointer;
         /* skipping OTHER_IMMEDIATE_0_LOWTAG */
         sizetab[LIST_POINTER_LOWTAG|(i<<N_LOWTAG_BITS)] = size_pointer;
-        sizetab[ODD_FIXNUM_LOWTAG|(i<<N_LOWTAG_BITS)] = size_immediate;
         sizetab[INSTANCE_POINTER_LOWTAG|(i<<N_LOWTAG_BITS)] = size_pointer;
         /* skipping OTHER_IMMEDIATE_1_LOWTAG */
         sizetab[OTHER_POINTER_LOWTAG|(i<<N_LOWTAG_BITS)] = size_pointer;
@@ -2263,16 +2249,16 @@ gc_init_tables(void)
         size_vector_unsigned_byte_16;
     sizetab[SIMPLE_ARRAY_UNSIGNED_BYTE_16_WIDETAG] =
         size_vector_unsigned_byte_16;
-#ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_29_WIDETAG
-    sizetab[SIMPLE_ARRAY_UNSIGNED_BYTE_29_WIDETAG] =
+#if (N_WORD_BITS == 32)
+    sizetab[SIMPLE_ARRAY_UNSIGNED_FIXNUM_WIDETAG] =
         size_vector_unsigned_byte_32;
 #endif
     sizetab[SIMPLE_ARRAY_UNSIGNED_BYTE_31_WIDETAG] =
         size_vector_unsigned_byte_32;
     sizetab[SIMPLE_ARRAY_UNSIGNED_BYTE_32_WIDETAG] =
         size_vector_unsigned_byte_32;
-#ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_60_WIDETAG
-    sizetab[SIMPLE_ARRAY_UNSIGNED_BYTE_60_WIDETAG] =
+#if (N_WORD_BITS == 64)
+    sizetab[SIMPLE_ARRAY_UNSIGNED_FIXNUM_WIDETAG] =
         size_vector_unsigned_byte_64;
 #endif
 #ifdef SIMPLE_ARRAY_UNSIGNED_BYTE_63_WIDETAG
@@ -2290,16 +2276,16 @@ gc_init_tables(void)
     sizetab[SIMPLE_ARRAY_SIGNED_BYTE_16_WIDETAG] =
         size_vector_unsigned_byte_16;
 #endif
-#ifdef SIMPLE_ARRAY_SIGNED_BYTE_30_WIDETAG
-    sizetab[SIMPLE_ARRAY_SIGNED_BYTE_30_WIDETAG] =
+#if (N_WORD_BITS == 32)
+    sizetab[SIMPLE_ARRAY_FIXNUM_WIDETAG] =
         size_vector_unsigned_byte_32;
 #endif
 #ifdef SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG
     sizetab[SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG] =
         size_vector_unsigned_byte_32;
 #endif
-#ifdef SIMPLE_ARRAY_SIGNED_BYTE_61_WIDETAG
-    sizetab[SIMPLE_ARRAY_SIGNED_BYTE_61_WIDETAG] =
+#if (N_WORD_BITS == 64)
+    sizetab[SIMPLE_ARRAY_FIXNUM_WIDETAG] =
         size_vector_unsigned_byte_64;
 #endif
 #ifdef SIMPLE_ARRAY_SIGNED_BYTE_64_WIDETAG
@@ -2403,6 +2389,231 @@ gc_search_space(lispobj *start, size_t words, lispobj *pointer)
     return (NULL);
 }
 
+/* Helper for valid_lisp_pointer_p (below) and
+ * possibly_valid_dynamic_space_pointer (gencgc).
+ *
+ * pointer is the pointer to validate, and start_addr is the address
+ * of the enclosing object.
+ */
+int
+looks_like_valid_lisp_pointer_p(lispobj pointer, lispobj *start_addr)
+{
+    if (!is_lisp_pointer(pointer)) {
+        return 0;
+    }
+
+    /* Check that the object pointed to is consistent with the pointer
+     * low tag. */
+    switch (lowtag_of(pointer)) {
+    case FUN_POINTER_LOWTAG:
+        /* Start_addr should be the enclosing code object, or a closure
+         * header. */
+        switch (widetag_of(*start_addr)) {
+        case CODE_HEADER_WIDETAG:
+            /* Make sure we actually point to a function in the code object,
+             * as opposed to a random point there. */
+            if (SIMPLE_FUN_HEADER_WIDETAG==widetag_of(native_pointer(pointer)[0]))
+                return 1;
+            else
+                return 0;
+        case CLOSURE_HEADER_WIDETAG:
+        case FUNCALLABLE_INSTANCE_HEADER_WIDETAG:
+            if (pointer != make_lispobj(start_addr, FUN_POINTER_LOWTAG)) {
+                return 0;
+            }
+            break;
+        default:
+            return 0;
+        }
+        break;
+    case LIST_POINTER_LOWTAG:
+        if (pointer != make_lispobj(start_addr, LIST_POINTER_LOWTAG)) {
+            return 0;
+        }
+        /* Is it plausible cons? */
+        if ((is_lisp_pointer(start_addr[0]) ||
+             is_lisp_immediate(start_addr[0])) &&
+            (is_lisp_pointer(start_addr[1]) ||
+             is_lisp_immediate(start_addr[1])))
+            break;
+        else {
+            return 0;
+        }
+    case INSTANCE_POINTER_LOWTAG:
+        if (pointer != make_lispobj(start_addr, INSTANCE_POINTER_LOWTAG)) {
+            return 0;
+        }
+        if (widetag_of(start_addr[0]) != INSTANCE_HEADER_WIDETAG) {
+            return 0;
+        }
+        break;
+    case OTHER_POINTER_LOWTAG:
+
+#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
+        /* The all-architecture test below is good as far as it goes,
+         * but an LRA object is similar to a FUN-POINTER: It is
+         * embedded within a CODE-OBJECT pointed to by start_addr, and
+         * cannot be found by simply walking the heap, therefore we
+         * need to check for it. -- AB, 2010-Jun-04 */
+        if ((widetag_of(start_addr[0]) == CODE_HEADER_WIDETAG)) {
+            lispobj *potential_lra = native_pointer(pointer);
+            if ((widetag_of(potential_lra[0]) == RETURN_PC_HEADER_WIDETAG) &&
+                ((potential_lra - HeaderValue(potential_lra[0])) == start_addr)) {
+                return 1; /* It's as good as we can verify. */
+            }
+        }
+#endif
+
+        if (pointer != make_lispobj(start_addr, OTHER_POINTER_LOWTAG)) {
+            return 0;
+        }
+        /* Is it plausible?  Not a cons. XXX should check the headers. */
+        if (is_lisp_pointer(start_addr[0]) || ((start_addr[0] & 3) == 0)) {
+            return 0;
+        }
+        switch (widetag_of(start_addr[0])) {
+        case UNBOUND_MARKER_WIDETAG:
+        case NO_TLS_VALUE_MARKER_WIDETAG:
+        case CHARACTER_WIDETAG:
+#if N_WORD_BITS == 64
+        case SINGLE_FLOAT_WIDETAG:
+#endif
+            return 0;
+
+            /* only pointed to by function pointers? */
+        case CLOSURE_HEADER_WIDETAG:
+        case FUNCALLABLE_INSTANCE_HEADER_WIDETAG:
+            return 0;
+
+        case INSTANCE_HEADER_WIDETAG:
+            return 0;
+
+            /* the valid other immediate pointer objects */
+        case SIMPLE_VECTOR_WIDETAG:
+        case RATIO_WIDETAG:
+        case COMPLEX_WIDETAG:
+#ifdef COMPLEX_SINGLE_FLOAT_WIDETAG
+        case COMPLEX_SINGLE_FLOAT_WIDETAG:
+#endif
+#ifdef COMPLEX_DOUBLE_FLOAT_WIDETAG
+        case COMPLEX_DOUBLE_FLOAT_WIDETAG:
+#endif
+#ifdef COMPLEX_LONG_FLOAT_WIDETAG
+        case COMPLEX_LONG_FLOAT_WIDETAG:
+#endif
+        case SIMPLE_ARRAY_WIDETAG:
+        case COMPLEX_BASE_STRING_WIDETAG:
+#ifdef COMPLEX_CHARACTER_STRING_WIDETAG
+        case COMPLEX_CHARACTER_STRING_WIDETAG:
+#endif
+        case COMPLEX_VECTOR_NIL_WIDETAG:
+        case COMPLEX_BIT_VECTOR_WIDETAG:
+        case COMPLEX_VECTOR_WIDETAG:
+        case COMPLEX_ARRAY_WIDETAG:
+        case VALUE_CELL_HEADER_WIDETAG:
+        case SYMBOL_HEADER_WIDETAG:
+        case FDEFN_WIDETAG:
+        case CODE_HEADER_WIDETAG:
+        case BIGNUM_WIDETAG:
+#if N_WORD_BITS != 64
+        case SINGLE_FLOAT_WIDETAG:
+#endif
+        case DOUBLE_FLOAT_WIDETAG:
+#ifdef LONG_FLOAT_WIDETAG
+        case LONG_FLOAT_WIDETAG:
+#endif
+        case SIMPLE_BASE_STRING_WIDETAG:
+#ifdef SIMPLE_CHARACTER_STRING_WIDETAG
+        case SIMPLE_CHARACTER_STRING_WIDETAG:
+#endif
+        case SIMPLE_BIT_VECTOR_WIDETAG:
+        case SIMPLE_ARRAY_NIL_WIDETAG:
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_2_WIDETAG:
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_4_WIDETAG:
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_7_WIDETAG:
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_8_WIDETAG:
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_15_WIDETAG:
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_16_WIDETAG:
+
+        case SIMPLE_ARRAY_UNSIGNED_FIXNUM_WIDETAG:
+
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_31_WIDETAG:
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_32_WIDETAG:
+#ifdef  SIMPLE_ARRAY_UNSIGNED_BYTE_63_WIDETAG
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_63_WIDETAG:
+#endif
+#ifdef  SIMPLE_ARRAY_UNSIGNED_BYTE_64_WIDETAG
+        case SIMPLE_ARRAY_UNSIGNED_BYTE_64_WIDETAG:
+#endif
+#ifdef SIMPLE_ARRAY_SIGNED_BYTE_8_WIDETAG
+        case SIMPLE_ARRAY_SIGNED_BYTE_8_WIDETAG:
+#endif
+#ifdef SIMPLE_ARRAY_SIGNED_BYTE_16_WIDETAG
+        case SIMPLE_ARRAY_SIGNED_BYTE_16_WIDETAG:
+#endif
+
+        case SIMPLE_ARRAY_FIXNUM_WIDETAG:
+
+#ifdef SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG
+        case SIMPLE_ARRAY_SIGNED_BYTE_32_WIDETAG:
+#endif
+#ifdef SIMPLE_ARRAY_SIGNED_BYTE_64_WIDETAG
+        case SIMPLE_ARRAY_SIGNED_BYTE_64_WIDETAG:
+#endif
+        case SIMPLE_ARRAY_SINGLE_FLOAT_WIDETAG:
+        case SIMPLE_ARRAY_DOUBLE_FLOAT_WIDETAG:
+#ifdef SIMPLE_ARRAY_LONG_FLOAT_WIDETAG
+        case SIMPLE_ARRAY_LONG_FLOAT_WIDETAG:
+#endif
+#ifdef SIMPLE_ARRAY_COMPLEX_SINGLE_FLOAT_WIDETAG
+        case SIMPLE_ARRAY_COMPLEX_SINGLE_FLOAT_WIDETAG:
+#endif
+#ifdef SIMPLE_ARRAY_COMPLEX_DOUBLE_FLOAT_WIDETAG
+        case SIMPLE_ARRAY_COMPLEX_DOUBLE_FLOAT_WIDETAG:
+#endif
+#ifdef SIMPLE_ARRAY_COMPLEX_LONG_FLOAT_WIDETAG
+        case SIMPLE_ARRAY_COMPLEX_LONG_FLOAT_WIDETAG:
+#endif
+        case SAP_WIDETAG:
+        case WEAK_POINTER_WIDETAG:
+            break;
+
+        default:
+            return 0;
+        }
+        break;
+    default:
+        return 0;
+    }
+
+    /* looks good */
+    return 1;
+}
+
+/* Used by the debugger to validate possibly bogus pointers before
+ * calling MAKE-LISP-OBJ on them.
+ *
+ * FIXME: We would like to make this perfect, because if the debugger
+ * constructs a reference to a bugs lisp object, and it ends up in a
+ * location scavenged by the GC all hell breaks loose.
+ *
+ * Whereas possibly_valid_dynamic_space_pointer has to be conservative
+ * and return true for all valid pointers, this could actually be eager
+ * and lie about a few pointers without bad results... but that should
+ * be reflected in the name.
+ */
+int
+valid_lisp_pointer_p(lispobj *pointer)
+{
+    lispobj *start;
+    if (((start=search_dynamic_space(pointer))!=NULL) ||
+        ((start=search_static_space(pointer))!=NULL) ||
+        ((start=search_read_only_space(pointer))!=NULL))
+        return looks_like_valid_lisp_pointer_p((lispobj)pointer, start);
+    else
+        return 0;
+}
+
 boolean
 maybe_gc(os_context_t *context)
 {
@@ -2432,7 +2643,7 @@ maybe_gc(os_context_t *context)
      * A kludgy alternative is to propagate the sigmask change to the
      * outer context.
      */
-#ifndef LISP_FEATURE_WIN32
+#if !(defined(LISP_FEATURE_WIN32) || defined(LISP_FEATURE_SB_SAFEPOINT))
     check_gc_signals_unblocked_or_lose(os_context_sigmask_addr(context));
     unblock_gc_signals(0, 0);
 #endif
@@ -2457,8 +2668,10 @@ maybe_gc(os_context_t *context)
         sigset_t *context_sigmask = os_context_sigmask_addr(context);
         if (!deferrables_blocked_p(context_sigmask)) {
             thread_sigmask(SIG_SETMASK, context_sigmask, 0);
+#ifndef LISP_FEATURE_SB_SAFEPOINT
             check_gc_signals_unblocked_or_lose(0);
 #endif
+#endif
             FSHOW((stderr, "/maybe_gc: calling POST_GC\n"));
             funcall0(StaticSymbolFunction(POST_GC));
 #ifndef LISP_FEATURE_WIN32
@@ -2510,12 +2723,13 @@ 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;
+    /* On these targets scrubbing from C is a bad idea, so we punt to
+     * a routine in $ARCH-assem.S. */
+    extern void arch_scrub_control_stack(struct thread *, os_vm_address_t, os_vm_address_t);
+    arch_scrub_control_stack(th, guard_page_address, hard_guard_page_address);
 #else
-    sp = access_control_stack_pointer(th);
-#endif
+    lispobj *sp = access_control_stack_pointer(th);
  scrub:
     if ((((os_vm_address_t)sp < (hard_guard_page_address + os_vm_page_size)) &&
          ((os_vm_address_t)sp >= hard_guard_page_address)) ||
@@ -2544,10 +2758,57 @@ scrub_control_stack(void)
             goto scrub;
     } while (((unsigned long)++sp) & (BYTES_ZERO_BEFORE_END - 1));
 #endif
+#endif /* LISP_FEATURE_C_STACK_IS_CONTROL_STACK */
 }
 
 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
 
+void
+scavenge_control_stack(struct thread *th)
+{
+    lispobj *object_ptr;
+
+    /* In order to properly support dynamic-extent allocation of
+     * non-CONS objects, the control stack requires special handling.
+     * Rather than calling scavenge() directly, grovel over it fixing
+     * broken hearts, scavenging pointers to oldspace, and pitching a
+     * fit when encountering unboxed data.  This prevents stray object
+     * headers from causing the scavenger to blow past the end of the
+     * stack (an error case checked in scavenge()).  We don't worry
+     * about treating unboxed words as boxed or vice versa, because
+     * the compiler isn't allowed to store unboxed objects on the
+     * control stack.  -- AB, 2011-Dec-02 */
+
+    for (object_ptr = th->control_stack_start;
+         object_ptr < access_control_stack_pointer(th);
+         object_ptr++) {
+
+        lispobj object = *object_ptr;
+#ifdef LISP_FEATURE_GENCGC
+        if (forwarding_pointer_p(object_ptr))
+            lose("unexpected forwarding pointer in scavenge_control_stack: %p, start=%p, end=%p\n",
+                 object_ptr, th->control_stack_start, access_control_stack_pointer(th));
+#endif
+        if (is_lisp_pointer(object) && from_space_p(object)) {
+            /* It currently points to old space. Check for a
+             * forwarding pointer. */
+            lispobj *ptr = native_pointer(object);
+            if (forwarding_pointer_p(ptr)) {
+                /* Yes, there's a forwarding pointer. */
+                *object_ptr = LOW_WORD(forwarding_pointer_value(ptr));
+            } else {
+                /* Scavenge that pointer. */
+                long n_words_scavenged =
+                    (scavtab[widetag_of(object)])(object_ptr, object);
+                gc_assert(n_words_scavenged == 1);
+            }
+        } else if (scavtab[widetag_of(object)] == scav_lose) {
+            lose("unboxed object in scavenge_control_stack: %p->%x, start=%p, end=%p\n",
+                 object_ptr, object, th->control_stack_start, access_control_stack_pointer(th));
+        }
+    }
+}
+
 /* Scavenging Interrupt Contexts */
 
 static int boxed_registers[] = BOXED_REGISTERS;