1.0.41.15: gencgc: Implement object pinning for non-x86oids.
[sbcl.git] / src / runtime / gencgc.c
index ced46d0..74b818e 100644 (file)
@@ -41,6 +41,7 @@
 #include "gc.h"
 #include "gc-internal.h"
 #include "thread.h"
+#include "pseudo-atomic.h"
 #include "alloc.h"
 #include "genesis/vector.h"
 #include "genesis/weak-pointer.h"
 #if defined(LUTEX_WIDETAG)
 #include "pthread-lutex.h"
 #endif
+#if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
+#include "genesis/cons.h"
+#endif
 
 /* forward declarations */
 page_index_t  gc_find_freeish_pages(long *restart_page_ptr, long nbytes,
-                                    int unboxed);
+                                    int page_type_flag);
 
 \f
 /*
@@ -68,9 +72,7 @@ page_index_t  gc_find_freeish_pages(long *restart_page_ptr, long nbytes,
  * scratch space by the collector, and should never get collected.
  */
 enum {
-    HIGHEST_NORMAL_GENERATION = 5,
-    PSEUDO_STATIC_GENERATION,
-    SCRATCH_GENERATION,
+    SCRATCH_GENERATION = PSEUDO_STATIC_GENERATION+1,
     NUM_GENERATIONS
 };
 
@@ -88,7 +90,7 @@ long large_object_size = 4 * PAGE_BYTES;
 
 /* the verbosity level. All non-error messages are disabled at level 0;
  * and only a few rare messages are printed at level 1. */
-#ifdef QSHOW
+#if QSHOW
 boolean gencgc_verbose = 1;
 #else
 boolean gencgc_verbose = 0;
@@ -165,6 +167,48 @@ static boolean conservative_stack = 1;
 page_index_t page_table_pages;
 struct page *page_table;
 
+static inline boolean page_allocated_p(page_index_t page) {
+    return (page_table[page].allocated != FREE_PAGE_FLAG);
+}
+
+static inline boolean page_no_region_p(page_index_t page) {
+    return !(page_table[page].allocated & OPEN_REGION_PAGE_FLAG);
+}
+
+static inline boolean page_allocated_no_region_p(page_index_t page) {
+    return ((page_table[page].allocated & (UNBOXED_PAGE_FLAG | BOXED_PAGE_FLAG))
+            && page_no_region_p(page));
+}
+
+static inline boolean page_free_p(page_index_t page) {
+    return (page_table[page].allocated == FREE_PAGE_FLAG);
+}
+
+static inline boolean page_boxed_p(page_index_t page) {
+    return (page_table[page].allocated & BOXED_PAGE_FLAG);
+}
+
+static inline boolean code_page_p(page_index_t page) {
+    return (page_table[page].allocated & CODE_PAGE_FLAG);
+}
+
+static inline boolean page_boxed_no_region_p(page_index_t page) {
+    return page_boxed_p(page) && page_no_region_p(page);
+}
+
+static inline boolean page_unboxed_p(page_index_t page) {
+    /* Both flags set == boxed code page */
+    return ((page_table[page].allocated & UNBOXED_PAGE_FLAG)
+            && !page_boxed_p(page));
+}
+
+static inline boolean protect_page_p(page_index_t page, generation_index_t generation) {
+    return (page_boxed_no_region_p(page)
+            && (page_table[page].bytes_used != 0)
+            && !page_table[page].dont_move
+            && (page_table[page].gen == generation));
+}
+
 /* To map addresses to page structures the address of the first page
  * is needed. */
 static void *heap_base = NULL;
@@ -214,7 +258,12 @@ size_t void_diff(void *x, void *y)
     return (pointer_sized_uint_t)x - (pointer_sized_uint_t)y;
 }
 
-/* a structure to hold the state of a generation */
+/* a structure to hold the state of a generation
+ *
+ * CAUTION: If you modify this, make sure to touch up the alien
+ * definition in src/code/gc.lisp accordingly. ...or better yes,
+ * deal with the FIXME there...
+ */
 struct generation {
 
     /* the first page that gc_alloc() checks on its next call */
@@ -244,9 +293,9 @@ struct generation {
     /* the number of GCs since the last raise */
     int num_gc;
 
-    /* the average age after which a GC will raise objects to the
+    /* the number of GCs to run on the generations before raising objects to the
      * next generation */
-    int trigger_age;
+    int number_of_gcs_before_promotion;
 
     /* the cumulative sum of the bytes allocated to this generation. It is
      * cleared after a GC on this generations, and update before new
@@ -258,7 +307,7 @@ struct generation {
     /* a minimum average memory age before a GC will occur helps
      * prevent a GC when a large number of new live objects have been
      * added, in which case a GC could be a waste of time */
-    double min_av_mem_age;
+    double minimum_age_before_gc;
 
     /* A linked list of lutex structures in this generation, used for
      * implementing lutex finalization. */
@@ -294,15 +343,16 @@ generation_index_t gencgc_oldest_gen_to_gc = HIGHEST_NORMAL_GENERATION;
  * integrated with the Lisp code. */
 page_index_t last_free_page;
 \f
+#ifdef LISP_FEATURE_SB_THREAD
 /* This lock is to prevent multiple threads from simultaneously
  * allocating new regions which overlap each other.  Note that the
  * majority of GC is single-threaded, but alloc() may be called from
  * >1 thread at a time and must be thread-safe.  This lock must be
  * seized before all accesses to generations[] or to parts of
  * page_table[] that other threads may want to see */
-
-#ifdef LISP_FEATURE_SB_THREAD
 static pthread_mutex_t free_pages_lock = PTHREAD_MUTEX_INITIALIZER;
+/* This lock is used to protect non-thread-local allocation. */
+static pthread_mutex_t allocation_lock = PTHREAD_MUTEX_INITIALIZER;
 #endif
 
 \f
@@ -319,7 +369,7 @@ count_write_protect_generation_pages(generation_index_t generation)
     unsigned long count = 0;
 
     for (i = 0; i < last_free_page; i++)
-        if ((page_table[i].allocated != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].gen == generation)
             && (page_table[i].write_protected == 1))
             count++;
@@ -334,20 +384,20 @@ count_generation_pages(generation_index_t generation)
     long count = 0;
 
     for (i = 0; i < last_free_page; i++)
-        if ((page_table[i].allocated != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].gen == generation))
             count++;
     return count;
 }
 
-#ifdef QSHOW
+#if QSHOW
 static long
 count_dont_move_pages(void)
 {
     page_index_t i;
     long count = 0;
     for (i = 0; i < last_free_page; i++) {
-        if ((page_table[i].allocated != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].dont_move != 0)) {
             ++count;
         }
@@ -364,7 +414,7 @@ count_generation_bytes_allocated (generation_index_t gen)
     page_index_t i;
     unsigned long result = 0;
     for (i = 0; i < last_free_page; i++) {
-        if ((page_table[i].allocated != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].gen == gen))
             result += page_table[i].bytes_used;
     }
@@ -372,8 +422,8 @@ count_generation_bytes_allocated (generation_index_t gen)
 }
 
 /* Return the average age of the memory in a generation. */
-static double
-gen_av_mem_age(generation_index_t gen)
+extern double
+generation_average_age(generation_index_t gen)
 {
     if (generations[gen].bytes_allocated == 0)
         return 0.0;
@@ -385,10 +435,10 @@ gen_av_mem_age(generation_index_t gen)
 
 /* The verbose argument controls how much to print: 0 for normal
  * level of detail; 1 for debugging. */
-static void
-print_generation_stats(int verbose) /* FIXME: should take FILE argument */
+extern void
+print_generation_stats() /* FIXME: should take FILE argument, or construct a string */
 {
-    generation_index_t i, gens;
+    generation_index_t i;
 
 #if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
 #define FPU_STATE_SIZE 27
@@ -402,17 +452,11 @@ print_generation_stats(int verbose) /* FIXME: should take FILE argument */
      * so they need to be saved and reset for C. */
     fpu_save(fpu_state);
 
-    /* highest generation to print */
-    if (verbose)
-        gens = SCRATCH_GENERATION;
-    else
-        gens = PSEUDO_STATIC_GENERATION;
-
     /* Print the heap stats. */
     fprintf(stderr,
             " Gen StaPg UbSta LaSta LUbSt Boxed Unboxed LB   LUB  !move  Alloc  Waste   Trig    WP  GCs Mem-age\n");
 
-    for (i = 0; i < gens; i++) {
+    for (i = 0; i < SCRATCH_GENERATION; i++) {
         page_index_t j;
         long boxed_cnt = 0;
         long unboxed_cnt = 0;
@@ -425,7 +469,7 @@ print_generation_stats(int verbose) /* FIXME: should take FILE argument */
 
                 /* Count the number of boxed pages within the given
                  * generation. */
-                if (page_table[j].allocated & BOXED_PAGE_FLAG) {
+                if (page_boxed_p(j)) {
                     if (page_table[j].large_object)
                         large_boxed_cnt++;
                     else
@@ -434,7 +478,7 @@ print_generation_stats(int verbose) /* FIXME: should take FILE argument */
                 if(page_table[j].dont_move) pinned_cnt++;
                 /* Count the number of unboxed pages within the given
                  * generation. */
-                if (page_table[j].allocated & UNBOXED_PAGE_FLAG) {
+                if (page_unboxed_p(j)) {
                     if (page_table[j].large_object)
                         large_unboxed_cnt++;
                     else
@@ -462,9 +506,10 @@ print_generation_stats(int verbose) /* FIXME: should take FILE argument */
                 generations[i].gc_trigger,
                 count_write_protect_generation_pages(i),
                 generations[i].num_gc,
-                gen_av_mem_age(i));
+                generation_average_age(i));
     }
-    fprintf(stderr,"   Total bytes allocated=%ld\n", bytes_allocated);
+    fprintf(stderr,"   Total bytes allocated    = %lu\n", bytes_allocated);
+    fprintf(stderr,"   Dynamic-space-size bytes = %u\n", dynamic_space_size);
 
     fpu_restore(fpu_state);
 }
@@ -589,6 +634,55 @@ struct alloc_region unboxed_region;
 /* The generation currently being allocated to. */
 static generation_index_t gc_alloc_generation;
 
+static inline page_index_t
+generation_alloc_start_page(generation_index_t generation, int page_type_flag, int large)
+{
+    if (large) {
+        if (UNBOXED_PAGE_FLAG == page_type_flag) {
+            return generations[generation].alloc_large_unboxed_start_page;
+        } else if (BOXED_PAGE_FLAG & page_type_flag) {
+            /* Both code and data. */
+            return generations[generation].alloc_large_start_page;
+        } else {
+            lose("bad page type flag: %d", page_type_flag);
+        }
+    } else {
+        if (UNBOXED_PAGE_FLAG == page_type_flag) {
+            return generations[generation].alloc_unboxed_start_page;
+        } else if (BOXED_PAGE_FLAG & page_type_flag) {
+            /* Both code and data. */
+            return generations[generation].alloc_start_page;
+        } else {
+            lose("bad page_type_flag: %d", page_type_flag);
+        }
+    }
+}
+
+static inline void
+set_generation_alloc_start_page(generation_index_t generation, int page_type_flag, int large,
+                                page_index_t page)
+{
+    if (large) {
+        if (UNBOXED_PAGE_FLAG == page_type_flag) {
+            generations[generation].alloc_large_unboxed_start_page = page;
+        } else if (BOXED_PAGE_FLAG & page_type_flag) {
+            /* Both code and data. */
+            generations[generation].alloc_large_start_page = page;
+        } else {
+            lose("bad page type flag: %d", page_type_flag);
+        }
+    } else {
+        if (UNBOXED_PAGE_FLAG == page_type_flag) {
+            generations[generation].alloc_unboxed_start_page = page;
+        } else if (BOXED_PAGE_FLAG & page_type_flag) {
+            /* Both code and data. */
+            generations[generation].alloc_start_page = page;
+        } else {
+            lose("bad page type flag: %d", page_type_flag);
+        }
+    }
+}
+
 /* Find a new region with room for at least the given number of bytes.
  *
  * It starts looking at the current generation's alloc_start_page. So
@@ -613,7 +707,7 @@ static generation_index_t gc_alloc_generation;
  * are allocated, although they will initially be empty.
  */
 static void
-gc_alloc_new_region(long nbytes, int unboxed, struct alloc_region *alloc_region)
+gc_alloc_new_region(long nbytes, int page_type_flag, struct alloc_region *alloc_region)
 {
     page_index_t first_page;
     page_index_t last_page;
@@ -633,14 +727,8 @@ gc_alloc_new_region(long nbytes, int unboxed, struct alloc_region *alloc_region)
               && (alloc_region->free_pointer == alloc_region->end_addr));
     ret = thread_mutex_lock(&free_pages_lock);
     gc_assert(ret == 0);
-    if (unboxed) {
-        first_page =
-            generations[gc_alloc_generation].alloc_unboxed_start_page;
-    } else {
-        first_page =
-            generations[gc_alloc_generation].alloc_start_page;
-    }
-    last_page=gc_find_freeish_pages(&first_page,nbytes,unboxed);
+    first_page = generation_alloc_start_page(gc_alloc_generation, page_type_flag, 0);
+    last_page=gc_find_freeish_pages(&first_page, nbytes, page_type_flag);
     bytes_found=(PAGE_BYTES - page_table[first_page].bytes_used)
             + npage_bytes(last_page-first_page);
 
@@ -656,29 +744,20 @@ gc_alloc_new_region(long nbytes, int unboxed, struct alloc_region *alloc_region)
 
     /* The first page may have already been in use. */
     if (page_table[first_page].bytes_used == 0) {
-        if (unboxed)
-            page_table[first_page].allocated = UNBOXED_PAGE_FLAG;
-        else
-            page_table[first_page].allocated = BOXED_PAGE_FLAG;
+        page_table[first_page].allocated = page_type_flag;
         page_table[first_page].gen = gc_alloc_generation;
         page_table[first_page].large_object = 0;
         page_table[first_page].region_start_offset = 0;
     }
 
-    if (unboxed)
-        gc_assert(page_table[first_page].allocated == UNBOXED_PAGE_FLAG);
-    else
-        gc_assert(page_table[first_page].allocated == BOXED_PAGE_FLAG);
+    gc_assert(page_table[first_page].allocated == page_type_flag);
     page_table[first_page].allocated |= OPEN_REGION_PAGE_FLAG;
 
     gc_assert(page_table[first_page].gen == gc_alloc_generation);
     gc_assert(page_table[first_page].large_object == 0);
 
     for (i = first_page+1; i <= last_page; i++) {
-        if (unboxed)
-            page_table[i].allocated = UNBOXED_PAGE_FLAG;
-        else
-            page_table[i].allocated = BOXED_PAGE_FLAG;
+        page_table[i].allocated = page_type_flag;
         page_table[i].gen = gc_alloc_generation;
         page_table[i].large_object = 0;
         /* This may not be necessary for unboxed regions (think it was
@@ -829,7 +908,7 @@ add_new_area(page_index_t first_page, size_t offset, size_t size)
  * it is safe to try to re-update the page table of this reset
  * alloc_region. */
 void
-gc_alloc_update_page_tables(int unboxed, struct alloc_region *alloc_region)
+gc_alloc_update_page_tables(int page_type_flag, struct alloc_region *alloc_region)
 {
     int more;
     page_index_t first_page;
@@ -869,10 +948,7 @@ gc_alloc_update_page_tables(int unboxed, struct alloc_region *alloc_region)
             gc_assert(page_table[first_page].region_start_offset == 0);
         page_table[first_page].allocated &= ~(OPEN_REGION_PAGE_FLAG);
 
-        if (unboxed)
-            gc_assert(page_table[first_page].allocated == UNBOXED_PAGE_FLAG);
-        else
-            gc_assert(page_table[first_page].allocated == BOXED_PAGE_FLAG);
+        gc_assert(page_table[first_page].allocated & page_type_flag);
         gc_assert(page_table[first_page].gen == gc_alloc_generation);
         gc_assert(page_table[first_page].large_object == 0);
 
@@ -896,10 +972,7 @@ gc_alloc_update_page_tables(int unboxed, struct alloc_region *alloc_region)
          * region, and set the bytes_used. */
         while (more) {
             page_table[next_page].allocated &= ~(OPEN_REGION_PAGE_FLAG);
-            if (unboxed)
-                gc_assert(page_table[next_page].allocated==UNBOXED_PAGE_FLAG);
-            else
-                gc_assert(page_table[next_page].allocated == BOXED_PAGE_FLAG);
+            gc_assert(page_table[next_page].allocated & page_type_flag);
             gc_assert(page_table[next_page].bytes_used == 0);
             gc_assert(page_table[next_page].gen == gc_alloc_generation);
             gc_assert(page_table[next_page].large_object == 0);
@@ -930,14 +1003,10 @@ gc_alloc_update_page_tables(int unboxed, struct alloc_region *alloc_region)
 
         /* Set the generations alloc restart page to the last page of
          * the region. */
-        if (unboxed)
-            generations[gc_alloc_generation].alloc_unboxed_start_page =
-                next_page-1;
-        else
-            generations[gc_alloc_generation].alloc_start_page = next_page-1;
+        set_generation_alloc_start_page(gc_alloc_generation, page_type_flag, 0, next_page-1);
 
         /* Add the region to the new_areas if requested. */
-        if (!unboxed)
+        if (BOXED_PAGE_FLAG & page_type_flag)
             add_new_area(first_page,orig_first_page_bytes_used, region_size);
 
         /*
@@ -971,38 +1040,30 @@ static inline void *gc_quick_alloc(long nbytes);
 
 /* Allocate a possibly large object. */
 void *
-gc_alloc_large(long nbytes, int unboxed, struct alloc_region *alloc_region)
+gc_alloc_large(long nbytes, int page_type_flag, struct alloc_region *alloc_region)
 {
     page_index_t first_page;
     page_index_t last_page;
     int orig_first_page_bytes_used;
     long byte_cnt;
     int more;
-    long bytes_used;
+    unsigned long bytes_used;
     page_index_t next_page;
     int ret;
 
     ret = thread_mutex_lock(&free_pages_lock);
     gc_assert(ret == 0);
 
-    if (unboxed) {
-        first_page =
-            generations[gc_alloc_generation].alloc_large_unboxed_start_page;
-    } else {
-        first_page = generations[gc_alloc_generation].alloc_large_start_page;
-    }
+    first_page = generation_alloc_start_page(gc_alloc_generation, page_type_flag, 1);
     if (first_page <= alloc_region->last_page) {
         first_page = alloc_region->last_page+1;
     }
 
-    last_page=gc_find_freeish_pages(&first_page,nbytes,unboxed);
+    last_page=gc_find_freeish_pages(&first_page,nbytes, page_type_flag);
 
     gc_assert(first_page > alloc_region->last_page);
-    if (unboxed)
-        generations[gc_alloc_generation].alloc_large_unboxed_start_page =
-            last_page;
-    else
-        generations[gc_alloc_generation].alloc_large_start_page = last_page;
+
+    set_generation_alloc_start_page(gc_alloc_generation, page_type_flag, 1, last_page);
 
     /* Set up the pages. */
     orig_first_page_bytes_used = page_table[first_page].bytes_used;
@@ -1010,19 +1071,13 @@ gc_alloc_large(long nbytes, int unboxed, struct alloc_region *alloc_region)
     /* If the first page was free then set up the gen, and
      * region_start_offset. */
     if (page_table[first_page].bytes_used == 0) {
-        if (unboxed)
-            page_table[first_page].allocated = UNBOXED_PAGE_FLAG;
-        else
-            page_table[first_page].allocated = BOXED_PAGE_FLAG;
+        page_table[first_page].allocated = page_type_flag;
         page_table[first_page].gen = gc_alloc_generation;
         page_table[first_page].region_start_offset = 0;
         page_table[first_page].large_object = 1;
     }
 
-    if (unboxed)
-        gc_assert(page_table[first_page].allocated == UNBOXED_PAGE_FLAG);
-    else
-        gc_assert(page_table[first_page].allocated == BOXED_PAGE_FLAG);
+    gc_assert(page_table[first_page].allocated == page_type_flag);
     gc_assert(page_table[first_page].gen == gc_alloc_generation);
     gc_assert(page_table[first_page].large_object == 1);
 
@@ -1044,12 +1099,9 @@ gc_alloc_large(long nbytes, int unboxed, struct alloc_region *alloc_region)
      * region_start_offset pointer to the start of the region, and set
      * the bytes_used. */
     while (more) {
-        gc_assert(page_table[next_page].allocated == FREE_PAGE_FLAG);
+        gc_assert(page_free_p(next_page));
         gc_assert(page_table[next_page].bytes_used == 0);
-        if (unboxed)
-            page_table[next_page].allocated = UNBOXED_PAGE_FLAG;
-        else
-            page_table[next_page].allocated = BOXED_PAGE_FLAG;
+        page_table[next_page].allocated = page_type_flag;
         page_table[next_page].gen = gc_alloc_generation;
         page_table[next_page].large_object = 1;
 
@@ -1076,7 +1128,7 @@ gc_alloc_large(long nbytes, int unboxed, struct alloc_region *alloc_region)
     generations[gc_alloc_generation].bytes_allocated += nbytes;
 
     /* Add the region to the new_areas if requested. */
-    if (!unboxed)
+    if (BOXED_PAGE_FLAG & page_type_flag)
         add_new_area(first_page,orig_first_page_bytes_used,nbytes);
 
     /* Bump up last_free_page */
@@ -1103,6 +1155,7 @@ static page_index_t gencgc_alloc_start_page = -1;
 void
 gc_heap_exhausted_error_or_lose (long available, long requested)
 {
+    struct thread *thread = arch_os_get_current_thread();
     /* Write basic information before doing anything else: if we don't
      * call to lisp this is a must, and even if we do there is always
      * the danger that we bounce back here before the error has been
@@ -1111,25 +1164,38 @@ gc_heap_exhausted_error_or_lose (long available, long requested)
     fprintf(stderr, "Heap exhausted during %s: %ld bytes available, %ld requested.\n",
             gc_active_p ? "garbage collection" : "allocation",
             available, requested);
-    if (gc_active_p || (available == 0)) {
-        /* If we are in GC, or totally out of memory there is no way
-         * to sanely transfer control to the lisp-side of things.
-         */
-        struct thread *thread = arch_os_get_current_thread();
-        print_generation_stats(1);
+    print_generation_stats();
         fprintf(stderr, "GC control variables:\n");
-        fprintf(stderr, "          *GC-INHIBIT* = %s\n          *GC-PENDING* = %s\n",
+        fprintf(stderr, "   *GC-INHIBIT* = %s\n   *GC-PENDING* = %s\n",
                 SymbolValue(GC_INHIBIT,thread)==NIL ? "false" : "true",
-                SymbolValue(GC_PENDING,thread)==NIL ? "false" : "true");
+                (SymbolValue(GC_PENDING, thread) == T) ?
+                "true" : ((SymbolValue(GC_PENDING, thread) == NIL) ?
+                  "false" : "in progress"));
 #ifdef LISP_FEATURE_SB_THREAD
-        fprintf(stderr, " *STOP-FOR-GC-PENDING* = %s\n",
+        fprintf(stderr, "   *STOP-FOR-GC-PENDING* = %s\n",
                 SymbolValue(STOP_FOR_GC_PENDING,thread)==NIL ? "false" : "true");
 #endif
+    if (gc_active_p || (available == 0)) {
+        /* If we are in GC, or totally out of memory there is no way
+         * to sanely transfer control to the lisp-side of things.
+         */
         lose("Heap exhausted, game over.");
     }
     else {
         /* FIXME: assert free_pages_lock held */
         (void)thread_mutex_unlock(&free_pages_lock);
+        gc_assert(get_pseudo_atomic_atomic(thread));
+        clear_pseudo_atomic_atomic(thread);
+        if (get_pseudo_atomic_interrupted(thread))
+            do_pending_interrupt();
+        /* Another issue is that signalling HEAP-EXHAUSTED error leads
+         * to running user code at arbitrary places, even in a
+         * WITHOUT-INTERRUPTS which may lead to a deadlock without
+         * running out of the heap. So at this point all bets are
+         * off. */
+        if (SymbolValue(INTERRUPTS_ENABLED,thread) == NIL)
+            corruption_warning_and_maybe_lose
+                ("Signalling HEAP-EXHAUSTED in a WITHOUT-INTERRUPTS.");
         funcall2(StaticSymbolFunction(HEAP_EXHAUSTED_ERROR),
                  alloc_number(available), alloc_number(requested));
         lose("HEAP-EXHAUSTED-ERROR fell through");
@@ -1137,7 +1203,8 @@ gc_heap_exhausted_error_or_lose (long available, long requested)
 }
 
 page_index_t
-gc_find_freeish_pages(page_index_t *restart_page_ptr, long nbytes, int unboxed)
+gc_find_freeish_pages(page_index_t *restart_page_ptr, long nbytes,
+                      int page_type_flag)
 {
     page_index_t first_page, last_page;
     page_index_t restart_page = *restart_page_ptr;
@@ -1150,7 +1217,8 @@ gc_find_freeish_pages(page_index_t *restart_page_ptr, long nbytes, int unboxed)
         restart_page = gencgc_alloc_start_page;
     }
 
-    if (nbytes>=PAGE_BYTES) {
+    gc_assert(nbytes>=0);
+    if (((unsigned long)nbytes)>=PAGE_BYTES) {
         /* Search for a contiguous free space of at least nbytes,
          * aligned on a page boundary. The page-alignment is strictly
          * speaking needed only for objects at least large_object_size
@@ -1158,17 +1226,18 @@ gc_find_freeish_pages(page_index_t *restart_page_ptr, long nbytes, int unboxed)
         do {
             first_page = restart_page;
             while ((first_page < page_table_pages) &&
-                   (page_table[first_page].allocated != FREE_PAGE_FLAG))
+                   page_allocated_p(first_page))
                 first_page++;
 
             last_page = first_page;
             bytes_found = PAGE_BYTES;
             while ((bytes_found < nbytes) &&
                    (last_page < (page_table_pages-1)) &&
-                   (page_table[last_page+1].allocated == FREE_PAGE_FLAG)) {
+                   page_free_p(last_page+1)) {
                 last_page++;
                 bytes_found += PAGE_BYTES;
-                gc_assert(page_table[last_page].write_protected == 0);
+                gc_assert(0 == page_table[last_page].bytes_used);
+                gc_assert(0 == page_table[last_page].write_protected);
             }
             if (bytes_found > most_bytes_found)
                 most_bytes_found = bytes_found;
@@ -1182,13 +1251,13 @@ gc_find_freeish_pages(page_index_t *restart_page_ptr, long nbytes, int unboxed)
          * pages: this helps avoid excessive conservativism. */
         first_page = restart_page;
         while (first_page < page_table_pages) {
-            if (page_table[first_page].allocated == FREE_PAGE_FLAG)
+            if (page_free_p(first_page))
                 {
+                    gc_assert(0 == page_table[first_page].bytes_used);
                     bytes_found = PAGE_BYTES;
                     break;
                 }
-            else if ((page_table[first_page].allocated ==
-                      (unboxed ? UNBOXED_PAGE_FLAG : BOXED_PAGE_FLAG)) &&
+            else if ((page_table[first_page].allocated == page_type_flag) &&
                      (page_table[first_page].large_object == 0) &&
                      (page_table[first_page].gen == gc_alloc_generation) &&
                      (page_table[first_page].write_protected == 0) &&
@@ -1223,13 +1292,13 @@ gc_find_freeish_pages(page_index_t *restart_page_ptr, long nbytes, int unboxed)
  * functions will eventually call this  */
 
 void *
-gc_alloc_with_region(long nbytes,int unboxed_p, struct alloc_region *my_region,
+gc_alloc_with_region(long nbytes,int page_type_flag, struct alloc_region *my_region,
                      int quick_p)
 {
     void *new_free_pointer;
 
     if (nbytes>=large_object_size)
-        return gc_alloc_large(nbytes,unboxed_p,my_region);
+        return gc_alloc_large(nbytes, page_type_flag, my_region);
 
     /* Check whether there is room in the current alloc region. */
     new_free_pointer = my_region->free_pointer + nbytes;
@@ -1247,9 +1316,9 @@ gc_alloc_with_region(long nbytes,int unboxed_p, struct alloc_region *my_region,
         if (!quick_p &&
             void_diff(my_region->end_addr,my_region->free_pointer) <= 32) {
             /* If so, finished with the current region. */
-            gc_alloc_update_page_tables(unboxed_p, my_region);
+            gc_alloc_update_page_tables(page_type_flag, my_region);
             /* Set up a new region. */
-            gc_alloc_new_region(32 /*bytes*/, unboxed_p, my_region);
+            gc_alloc_new_region(32 /*bytes*/, page_type_flag, my_region);
         }
 
         return((void *)new_obj);
@@ -1258,51 +1327,43 @@ gc_alloc_with_region(long nbytes,int unboxed_p, struct alloc_region *my_region,
     /* Else not enough free space in the current region: retry with a
      * new region. */
 
-    gc_alloc_update_page_tables(unboxed_p, my_region);
-    gc_alloc_new_region(nbytes, unboxed_p, my_region);
-    return gc_alloc_with_region(nbytes,unboxed_p,my_region,0);
+    gc_alloc_update_page_tables(page_type_flag, my_region);
+    gc_alloc_new_region(nbytes, page_type_flag, my_region);
+    return gc_alloc_with_region(nbytes, page_type_flag, my_region,0);
 }
 
 /* these are only used during GC: all allocation from the mutator calls
  * alloc() -> gc_alloc_with_region() with the appropriate per-thread
  * region */
 
-void *
-gc_general_alloc(long nbytes,int unboxed_p,int quick_p)
-{
-    struct alloc_region *my_region =
-      unboxed_p ? &unboxed_region : &boxed_region;
-    return gc_alloc_with_region(nbytes,unboxed_p, my_region,quick_p);
-}
-
 static inline void *
 gc_quick_alloc(long nbytes)
 {
-    return gc_general_alloc(nbytes,ALLOC_BOXED,ALLOC_QUICK);
+    return gc_general_alloc(nbytes, BOXED_PAGE_FLAG, ALLOC_QUICK);
 }
 
 static inline void *
 gc_quick_alloc_large(long nbytes)
 {
-    return gc_general_alloc(nbytes,ALLOC_BOXED,ALLOC_QUICK);
+    return gc_general_alloc(nbytes, BOXED_PAGE_FLAG ,ALLOC_QUICK);
 }
 
 static inline void *
 gc_alloc_unboxed(long nbytes)
 {
-    return gc_general_alloc(nbytes,ALLOC_UNBOXED,0);
+    return gc_general_alloc(nbytes, UNBOXED_PAGE_FLAG, 0);
 }
 
 static inline void *
 gc_quick_alloc_unboxed(long nbytes)
 {
-    return gc_general_alloc(nbytes,ALLOC_UNBOXED,ALLOC_QUICK);
+    return gc_general_alloc(nbytes, UNBOXED_PAGE_FLAG, ALLOC_QUICK);
 }
 
 static inline void *
 gc_quick_alloc_large_unboxed(long nbytes)
 {
-    return gc_general_alloc(nbytes,ALLOC_UNBOXED,ALLOC_QUICK);
+    return gc_general_alloc(nbytes, UNBOXED_PAGE_FLAG, ALLOC_QUICK);
 }
 \f
 
@@ -1349,20 +1410,16 @@ copy_large_object(lispobj object, long nwords)
         remaining_bytes = nwords*N_WORD_BYTES;
         while (remaining_bytes > PAGE_BYTES) {
             gc_assert(page_table[next_page].gen == from_space);
-            gc_assert(page_table[next_page].allocated == BOXED_PAGE_FLAG);
+            gc_assert(page_boxed_p(next_page));
             gc_assert(page_table[next_page].large_object);
             gc_assert(page_table[next_page].region_start_offset ==
                       npage_bytes(next_page-first_page));
             gc_assert(page_table[next_page].bytes_used == PAGE_BYTES);
+            /* Should have been unprotected by unprotect_oldspace(). */
+            gc_assert(page_table[next_page].write_protected == 0);
 
             page_table[next_page].gen = new_space;
 
-            /* Remove any write-protection. We should be able to rely
-             * on the write-protect flag to avoid redundant calls. */
-            if (page_table[next_page].write_protected) {
-                os_protect(page_address(next_page), PAGE_BYTES, OS_VM_PROT_ALL);
-                page_table[next_page].write_protected = 0;
-            }
             remaining_bytes -= PAGE_BYTES;
             next_page++;
         }
@@ -1374,7 +1431,7 @@ copy_large_object(lispobj object, long nwords)
         gc_assert(page_table[next_page].bytes_used >= remaining_bytes);
 
         page_table[next_page].gen = new_space;
-        gc_assert(page_table[next_page].allocated == BOXED_PAGE_FLAG);
+        gc_assert(page_boxed_p(next_page));
 
         /* Adjust the bytes_used. */
         old_bytes_used = page_table[next_page].bytes_used;
@@ -1386,7 +1443,7 @@ copy_large_object(lispobj object, long nwords)
         next_page++;
         while ((old_bytes_used == PAGE_BYTES) &&
                (page_table[next_page].gen == from_space) &&
-               (page_table[next_page].allocated == BOXED_PAGE_FLAG) &&
+               page_boxed_p(next_page) &&
                page_table[next_page].large_object &&
                (page_table[next_page].region_start_offset ==
                 npage_bytes(next_page - first_page))) {
@@ -1471,9 +1528,10 @@ copy_large_unboxed_object(lispobj object, long nwords)
     gc_assert(from_space_p(object));
     gc_assert((nwords & 0x01) == 0);
 
-    if ((nwords > 1024*1024) && gencgc_verbose)
+    if ((nwords > 1024*1024) && gencgc_verbose) {
         FSHOW((stderr, "/copy_large_unboxed_object: %d bytes\n",
                nwords*N_WORD_BYTES));
+    }
 
     /* Check whether it's a large object. */
     first_page = find_page_index((void *)object);
@@ -1494,8 +1552,7 @@ copy_large_unboxed_object(lispobj object, long nwords)
         remaining_bytes = nwords*N_WORD_BYTES;
         while (remaining_bytes > PAGE_BYTES) {
             gc_assert(page_table[next_page].gen == from_space);
-            gc_assert((page_table[next_page].allocated == UNBOXED_PAGE_FLAG)
-                      || (page_table[next_page].allocated == BOXED_PAGE_FLAG));
+            gc_assert(page_allocated_no_region_p(next_page));
             gc_assert(page_table[next_page].large_object);
             gc_assert(page_table[next_page].region_start_offset ==
                       npage_bytes(next_page-first_page));
@@ -1526,8 +1583,7 @@ copy_large_unboxed_object(lispobj object, long nwords)
         next_page++;
         while ((old_bytes_used == PAGE_BYTES) &&
                (page_table[next_page].gen == from_space) &&
-               ((page_table[next_page].allocated == UNBOXED_PAGE_FLAG)
-                || (page_table[next_page].allocated == BOXED_PAGE_FLAG)) &&
+               page_allocated_no_region_p(next_page) &&
                page_table[next_page].large_object &&
                (page_table[next_page].region_start_offset ==
                 npage_bytes(next_page - first_page))) {
@@ -1544,10 +1600,11 @@ copy_large_unboxed_object(lispobj object, long nwords)
             next_page++;
         }
 
-        if ((bytes_freed > 0) && gencgc_verbose)
+        if ((bytes_freed > 0) && gencgc_verbose) {
             FSHOW((stderr,
                    "/copy_large_unboxed bytes_freed=%d\n",
                    bytes_freed));
+        }
 
         generations[from_space].bytes_allocated -=
             nwords*N_WORD_BYTES + bytes_freed;
@@ -1623,7 +1680,7 @@ sniff_code_object(struct code *code, unsigned long displacement)
         unsigned d2 = *((unsigned char *)p - 2);
         unsigned d3 = *((unsigned char *)p - 3);
         unsigned d4 = *((unsigned char *)p - 4);
-#ifdef QSHOW
+#if QSHOW
         unsigned d5 = *((unsigned char *)p - 5);
         unsigned d6 = *((unsigned char *)p - 6);
 #endif
@@ -2152,8 +2209,7 @@ search_dynamic_space(void *pointer)
     lispobj *start;
 
     /* The address may be invalid, so do some checks. */
-    if ((page_index == -1) ||
-        (page_table[page_index].allocated == FREE_PAGE_FLAG))
+    if ((page_index == -1) || page_free_p(page_index))
         return NULL;
     start = (lispobj *)page_region_start(page_index);
     return (gc_search_space(start,
@@ -2161,8 +2217,6 @@ search_dynamic_space(void *pointer)
                             (lispobj *)pointer));
 }
 
-#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
-
 /* Helper for valid_lisp_pointer_p and
  * possibly_valid_dynamic_space_pointer.
  *
@@ -2172,13 +2226,6 @@ search_dynamic_space(void *pointer)
 static int
 looks_like_valid_lisp_pointer_p(lispobj *pointer, lispobj *start_addr)
 {
-    /* We need to allow raw pointers into Code objects for return
-     * addresses. This will also pick up pointers to functions in code
-     * objects. */
-    if (widetag_of(*start_addr) == CODE_HEADER_WIDETAG)
-        /* XXX could do some further checks here */
-        return 1;
-
     if (!is_lisp_pointer((lispobj)pointer)) {
         return 0;
     }
@@ -2197,28 +2244,31 @@ looks_like_valid_lisp_pointer_p(lispobj *pointer, lispobj *start_addr)
         case FUNCALLABLE_INSTANCE_HEADER_WIDETAG:
             if ((unsigned long)pointer !=
                 ((unsigned long)start_addr+FUN_POINTER_LOWTAG)) {
-                if (gencgc_verbose)
+                if (gencgc_verbose) {
                     FSHOW((stderr,
                            "/Wf2: %x %x %x\n",
                            pointer, start_addr, *start_addr));
+                }
                 return 0;
             }
             break;
         default:
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wf3: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
         }
         break;
     case LIST_POINTER_LOWTAG:
         if ((unsigned long)pointer !=
             ((unsigned long)start_addr+LIST_POINTER_LOWTAG)) {
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wl1: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
         }
         /* Is it plausible cons? */
@@ -2228,44 +2278,66 @@ looks_like_valid_lisp_pointer_p(lispobj *pointer, lispobj *start_addr)
              is_lisp_immediate(start_addr[1])))
             break;
         else {
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wl2: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
         }
     case INSTANCE_POINTER_LOWTAG:
         if ((unsigned long)pointer !=
             ((unsigned long)start_addr+INSTANCE_POINTER_LOWTAG)) {
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wi1: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
         }
         if (widetag_of(start_addr[0]) != INSTANCE_HEADER_WIDETAG) {
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wi2: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             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 =
+                (lispobj *)(((unsigned long)pointer) - OTHER_POINTER_LOWTAG);
+            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 ((unsigned long)pointer !=
             ((unsigned long)start_addr+OTHER_POINTER_LOWTAG)) {
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wo1: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             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)) {
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wo2: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
         }
         switch (widetag_of(start_addr[0])) {
@@ -2275,26 +2347,29 @@ looks_like_valid_lisp_pointer_p(lispobj *pointer, lispobj *start_addr)
 #if N_WORD_BITS == 64
         case SINGLE_FLOAT_WIDETAG:
 #endif
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "*Wo3: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
 
             /* only pointed to by function pointers? */
         case CLOSURE_HEADER_WIDETAG:
         case FUNCALLABLE_INSTANCE_HEADER_WIDETAG:
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "*Wo4: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
 
         case INSTANCE_HEADER_WIDETAG:
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "*Wo5: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
 
             /* the valid other immediate pointer objects */
@@ -2397,18 +2472,20 @@ looks_like_valid_lisp_pointer_p(lispobj *pointer, lispobj *start_addr)
             break;
 
         default:
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 FSHOW((stderr,
                        "/Wo6: %x %x %x\n",
                        pointer, start_addr, *start_addr));
+            }
             return 0;
         }
         break;
     default:
-        if (gencgc_verbose)
+        if (gencgc_verbose) {
             FSHOW((stderr,
                    "*W?: %x %x %x\n",
                    pointer, start_addr, *start_addr));
+        }
         return 0;
     }
 
@@ -2440,6 +2517,8 @@ valid_lisp_pointer_p(lispobj *pointer)
         return 0;
 }
 
+#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
+
 /* Is there any possibility that pointer is a valid Lisp object
  * reference, and/or something else (e.g. subroutine call return
  * address) which should prevent us from moving the referred-to thing?
@@ -2457,6 +2536,8 @@ possibly_valid_dynamic_space_pointer(lispobj *pointer)
     return looks_like_valid_lisp_pointer_p(pointer, start_addr);
 }
 
+#endif  // defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
+
 /* Adjust large bignum and vector objects. This will adjust the
  * allocated region if the size has shrunk, and move unboxed objects
  * into unboxed pages. The pages are not promoted here, and the
@@ -2565,8 +2646,7 @@ maybe_adjust_large_object(lispobj *where)
     remaining_bytes = nwords*N_WORD_BYTES;
     while (remaining_bytes > PAGE_BYTES) {
         gc_assert(page_table[next_page].gen == from_space);
-        gc_assert((page_table[next_page].allocated == BOXED_PAGE_FLAG)
-                  || (page_table[next_page].allocated == UNBOXED_PAGE_FLAG));
+        gc_assert(page_allocated_no_region_p(next_page));
         gc_assert(page_table[next_page].large_object);
         gc_assert(page_table[next_page].region_start_offset ==
                   npage_bytes(next_page-first_page));
@@ -2601,8 +2681,7 @@ maybe_adjust_large_object(lispobj *where)
     next_page++;
     while ((old_bytes_used == PAGE_BYTES) &&
            (page_table[next_page].gen == from_space) &&
-           ((page_table[next_page].allocated == UNBOXED_PAGE_FLAG)
-            || (page_table[next_page].allocated == BOXED_PAGE_FLAG)) &&
+           page_allocated_no_region_p(next_page) &&
            page_table[next_page].large_object &&
            (page_table[next_page].region_start_offset ==
             npage_bytes(next_page - first_page))) {
@@ -2654,7 +2733,7 @@ preserve_pointer(void *addr)
 
     /* quick check 1: Address is quite likely to have been invalid. */
     if ((addr_page_index == -1)
-        || (page_table[addr_page_index].allocated == FREE_PAGE_FLAG)
+        || page_free_p(addr_page_index)
         || (page_table[addr_page_index].bytes_used == 0)
         || (page_table[addr_page_index].gen != from_space)
         /* Skip if already marked dont_move. */
@@ -2677,9 +2756,17 @@ preserve_pointer(void *addr)
      * address referring to something in a CodeObject). This is
      * expensive but important, since it vastly reduces the
      * probability that random garbage will be bogusly interpreted as
-     * a pointer which prevents a page from moving. */
-    if (!(possibly_valid_dynamic_space_pointer(addr)))
+     * a pointer which prevents a page from moving.
+     *
+     * This only needs to happen on x86oids, where this is used for
+     * conservative roots.  Non-x86oid systems only ever call this
+     * function on known-valid lisp objects. */
+#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
+    if (!(code_page_p(addr_page_index)
+          || (is_lisp_pointer((lispobj)addr) &&
+              possibly_valid_dynamic_space_pointer(addr))))
         return;
+#endif
 
     /* Find the beginning of the region.  Note that there may be
      * objects in the region preceding the one that we were passed a
@@ -2709,7 +2796,7 @@ preserve_pointer(void *addr)
          * free area in which case it's ignored here. Note it gets
          * through the valid pointer test above because the tail looks
          * like conses. */
-        if ((page_table[addr_page_index].allocated == FREE_PAGE_FLAG)
+        if (page_free_p(addr_page_index)
             || (page_table[addr_page_index].bytes_used == 0)
             /* Check the offset within the page. */
             || (((unsigned long)addr & (PAGE_BYTES - 1))
@@ -2748,7 +2835,7 @@ preserve_pointer(void *addr)
         /* Check whether this is the last page in this contiguous block.. */
         if ((page_table[i].bytes_used < PAGE_BYTES)
             /* ..or it is PAGE_BYTES and is the last in the block */
-            || (page_table[i+1].allocated == FREE_PAGE_FLAG)
+            || page_free_p(i+1)
             || (page_table[i+1].bytes_used == 0) /* next page free */
             || (page_table[i+1].gen != from_space) /* diff. gen */
             || (page_table[i+1].region_start_offset == 0))
@@ -2758,9 +2845,6 @@ preserve_pointer(void *addr)
     /* Check that the page is now static. */
     gc_assert(page_table[addr_page_index].dont_move != 0);
 }
-
-#endif  // defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
-
 \f
 /* If the given page is not write-protected, then scan it for pointers
  * to younger generations or the top temp. generation, if no
@@ -2785,14 +2869,14 @@ update_page_write_prot(page_index_t page)
     long num_words = page_table[page].bytes_used / N_WORD_BYTES;
 
     /* Shouldn't be a free page. */
-    gc_assert(page_table[page].allocated != FREE_PAGE_FLAG);
+    gc_assert(page_allocated_p(page));
     gc_assert(page_table[page].bytes_used != 0);
 
     /* Skip if it's already write-protected, pinned, or unboxed */
     if (page_table[page].write_protected
         /* FIXME: What's the reason for not write-protecting pinned pages? */
         || page_table[page].dont_move
-        || (page_table[page].allocated & UNBOXED_PAGE_FLAG))
+        || page_unboxed_p(page))
         return (0);
 
     /* Scan the page for pointers to younger generations or the
@@ -2805,7 +2889,7 @@ update_page_write_prot(page_index_t page)
         /* Check that it's in the dynamic space */
         if (index != -1)
             if (/* Does it point to a younger or the temp. generation? */
-                ((page_table[index].allocated != FREE_PAGE_FLAG)
+                (page_allocated_p(index)
                  && (page_table[index].bytes_used != 0)
                  && ((page_table[index].gen < gen)
                      || (page_table[index].gen == SCRATCH_GENERATION)))
@@ -2879,7 +2963,7 @@ scavenge_generations(generation_index_t from, generation_index_t to)
 
     for (i = 0; i < last_free_page; i++) {
         generation_index_t generation = page_table[i].gen;
-        if ((page_table[i].allocated & BOXED_PAGE_FLAG)
+        if (page_boxed_p(i)
             && (page_table[i].bytes_used != 0)
             && (generation != new_space)
             && (generation >= from)
@@ -2896,7 +2980,7 @@ scavenge_generations(generation_index_t from, generation_index_t to)
                     write_protected && page_table[last_page].write_protected;
                 if ((page_table[last_page].bytes_used < PAGE_BYTES)
                     /* Or it is PAGE_BYTES and is the last in the block */
-                    || (!(page_table[last_page+1].allocated & BOXED_PAGE_FLAG))
+                    || (!page_boxed_p(last_page+1))
                     || (page_table[last_page+1].bytes_used == 0)
                     || (page_table[last_page+1].gen != generation)
                     || (page_table[last_page+1].region_start_offset == 0))
@@ -2929,7 +3013,7 @@ scavenge_generations(generation_index_t from, generation_index_t to)
     /* Check that none of the write_protected pages in this generation
      * have been written to. */
     for (i = 0; i < page_table_pages; i++) {
-        if ((page_table[i].allocation != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].bytes_used != 0)
             && (page_table[i].gen == generation)
             && (page_table[i].write_protected_cleared != 0)) {
@@ -2983,7 +3067,7 @@ scavenge_newspace_generation_one_scan(generation_index_t generation)
            generation));
     for (i = 0; i < last_free_page; i++) {
         /* Note that this skips over open regions when it encounters them. */
-        if ((page_table[i].allocated & BOXED_PAGE_FLAG)
+        if (page_boxed_p(i)
             && (page_table[i].bytes_used != 0)
             && (page_table[i].gen == generation)
             && ((page_table[i].write_protected == 0)
@@ -3012,7 +3096,7 @@ scavenge_newspace_generation_one_scan(generation_index_t generation)
                  * contiguous block */
                 if ((page_table[last_page].bytes_used < PAGE_BYTES)
                     /* Or it is PAGE_BYTES and is the last in the block */
-                    || (!(page_table[last_page+1].allocated & BOXED_PAGE_FLAG))
+                    || (!page_boxed_p(last_page+1))
                     || (page_table[last_page+1].bytes_used == 0)
                     || (page_table[last_page+1].gen != generation)
                     || (page_table[last_page+1].region_start_offset == 0))
@@ -3112,8 +3196,9 @@ scavenge_newspace_generation(generation_index_t generation)
             /* New areas of objects allocated have been lost so need to do a
              * full scan to be sure! If this becomes a problem try
              * increasing NUM_NEW_AREAS. */
-            if (gencgc_verbose)
+            if (gencgc_verbose) {
                 SHOW("new_areas overflow, doing full scavenge");
+            }
 
             /* Don't need to record new areas that get scavenged
              * anyway during scavenge_newspace_generation_one_scan. */
@@ -3160,7 +3245,7 @@ scavenge_newspace_generation(generation_index_t generation)
     /* Check that none of the write_protected pages in this generation
      * have been written to. */
     for (i = 0; i < page_table_pages; i++) {
-        if ((page_table[i].allocation != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].bytes_used != 0)
             && (page_table[i].gen == generation)
             && (page_table[i].write_protected_cleared != 0)
@@ -3181,23 +3266,41 @@ static void
 unprotect_oldspace(void)
 {
     page_index_t i;
+    void *region_addr = 0;
+    void *page_addr = 0;
+    unsigned long region_bytes = 0;
 
     for (i = 0; i < last_free_page; i++) {
-        if ((page_table[i].allocated != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].bytes_used != 0)
             && (page_table[i].gen == from_space)) {
-            void *page_start;
-
-            page_start = (void *)page_address(i);
 
             /* Remove any write-protection. We should be able to rely
              * on the write-protect flag to avoid redundant calls. */
             if (page_table[i].write_protected) {
-                os_protect(page_start, PAGE_BYTES, OS_VM_PROT_ALL);
                 page_table[i].write_protected = 0;
+                page_addr = page_address(i);
+                if (!region_addr) {
+                    /* First region. */
+                    region_addr = page_addr;
+                    region_bytes = PAGE_BYTES;
+                } else if (region_addr + region_bytes == page_addr) {
+                    /* Region continue. */
+                    region_bytes += PAGE_BYTES;
+                } else {
+                    /* Unprotect previous region. */
+                    os_protect(region_addr, region_bytes, OS_VM_PROT_ALL);
+                    /* First page in new region. */
+                    region_addr = page_addr;
+                    region_bytes = PAGE_BYTES;
+                }
             }
         }
     }
+    if (region_addr) {
+        /* Unprotect last region. */
+        os_protect(region_addr, region_bytes, OS_VM_PROT_ALL);
+    }
 }
 
 /* Work through all the pages and free any in from_space. This
@@ -3215,7 +3318,7 @@ free_oldspace(void)
     do {
         /* Find a first page for the next region of pages. */
         while ((first_page < last_free_page)
-               && ((page_table[first_page].allocated == FREE_PAGE_FLAG)
+               && (page_free_p(first_page)
                    || (page_table[first_page].bytes_used == 0)
                    || (page_table[first_page].gen != from_space)))
             first_page++;
@@ -3233,21 +3336,12 @@ free_oldspace(void)
                 page_table[last_page].bytes_used;
             page_table[last_page].allocated = FREE_PAGE_FLAG;
             page_table[last_page].bytes_used = 0;
-
-            /* Remove any write-protection. We should be able to rely
-             * on the write-protect flag to avoid redundant calls. */
-            {
-                void  *page_start = (void *)page_address(last_page);
-
-                if (page_table[last_page].write_protected) {
-                    os_protect(page_start, PAGE_BYTES, OS_VM_PROT_ALL);
-                    page_table[last_page].write_protected = 0;
-                }
-            }
+            /* Should already be unprotected by unprotect_oldspace(). */
+            gc_assert(!page_table[last_page].write_protected);
             last_page++;
         }
         while ((last_page < last_free_page)
-               && (page_table[last_page].allocated != FREE_PAGE_FLAG)
+               && page_allocated_p(last_page)
                && (page_table[last_page].bytes_used != 0)
                && (page_table[last_page].gen == from_space));
 
@@ -3293,6 +3387,23 @@ print_ptr(lispobj *addr)
 }
 #endif
 
+static int
+is_in_stack_space(lispobj ptr)
+{
+    /* For space verification: Pointers can be valid if they point
+     * to a thread stack space.  This would be faster if the thread
+     * structures had page-table entries as if they were part of
+     * the heap space. */
+    struct thread *th;
+    for_each_thread(th) {
+        if ((th->control_stack_start <= (lispobj *)ptr) &&
+            (th->control_stack_end >= (lispobj *)ptr)) {
+            return 1;
+        }
+    }
+    return 0;
+}
+
 static void
 verify_space(lispobj *start, size_t words)
 {
@@ -3318,17 +3429,17 @@ verify_space(lispobj *start, size_t words)
             if (page_index != -1) {
                 /* If it's within the dynamic space it should point to a used
                  * page. XX Could check the offset too. */
-                if ((page_table[page_index].allocated != FREE_PAGE_FLAG)
+                if (page_allocated_p(page_index)
                     && (page_table[page_index].bytes_used == 0))
-                    lose ("Ptr %x @ %x sees free page.\n", thing, start);
+                    lose ("Ptr %p @ %p sees free page.\n", thing, start);
                 /* Check that it doesn't point to a forwarding pointer! */
                 if (*((lispobj *)native_pointer(thing)) == 0x01) {
-                    lose("Ptr %x @ %x sees forwarding ptr.\n", thing, start);
+                    lose("Ptr %p @ %p sees forwarding ptr.\n", thing, start);
                 }
                 /* Check that its not in the RO space as it would then be a
                  * pointer from the RO to the dynamic space. */
                 if (is_in_readonly_space) {
-                    lose("ptr to dynamic space %x from RO space %x\n",
+                    lose("ptr to dynamic space %p from RO space %x\n",
                          thing, start);
                 }
                 /* Does it point to a plausible object? This check slows
@@ -3342,13 +3453,16 @@ verify_space(lispobj *start, size_t words)
                  * dynamically. */
                 /*
                 if (!possibly_valid_dynamic_space_pointer((lispobj *)thing)) {
-                    lose("ptr %x to invalid object %x\n", thing, start);
+                    lose("ptr %p to invalid object %p\n", thing, start);
                 }
                 */
             } else {
+                extern void funcallable_instance_tramp;
                 /* Verify that it points to another valid space. */
-                if (!to_readonly_space && !to_static_space) {
-                    lose("Ptr %x @ %x sees junk.\n", thing, start);
+                if (!to_readonly_space && !to_static_space
+                    && (thing != (lispobj)&funcallable_instance_tramp)
+                    && !is_in_stack_space(thing)) {
+                    lose("Ptr %p @ %p sees junk.\n", thing, start);
                 }
             }
         } else {
@@ -3425,7 +3539,7 @@ verify_space(lispobj *start, size_t words)
                             /* Only when enabled */
                             && verify_dynamic_code_check) {
                             FSHOW((stderr,
-                                   "/code object at %x in the dynamic space\n",
+                                   "/code object at %p in the dynamic space\n",
                                    start));
                         }
 
@@ -3541,7 +3655,7 @@ verify_space(lispobj *start, size_t words)
                     break;
 
                 default:
-                    lose("Unhandled widetag 0x%x at 0x%x\n",
+                    lose("Unhandled widetag %p at %p\n",
                          widetag_of(*start), start);
                 }
             }
@@ -3583,7 +3697,7 @@ verify_generation(generation_index_t generation)
     page_index_t i;
 
     for (i = 0; i < last_free_page; i++) {
-        if ((page_table[i].allocated != FREE_PAGE_FLAG)
+        if (page_allocated_p(i)
             && (page_table[i].bytes_used != 0)
             && (page_table[i].gen == generation)) {
             page_index_t last_page;
@@ -3625,7 +3739,7 @@ verify_zero_fill(void)
     page_index_t page;
 
     for (page = 0; page < last_free_page; page++) {
-        if (page_table[page].allocated == FREE_PAGE_FLAG) {
+        if (page_free_p(page)) {
             /* The whole page should be zero filled. */
             long *start_addr = (long *)page_address(page);
             long size = 1024;
@@ -3683,10 +3797,7 @@ write_protect_generation_pages(generation_index_t generation)
     gc_assert(generation < SCRATCH_GENERATION);
 
     for (start = 0; start < last_free_page; start++) {
-        if ((page_table[start].allocated == BOXED_PAGE_FLAG)
-            && (page_table[start].bytes_used != 0)
-            && !page_table[start].dont_move
-            && (page_table[start].gen == generation))  {
+        if (protect_page_p(start, generation)) {
             void *page_start;
             page_index_t last;
 
@@ -3694,10 +3805,7 @@ write_protect_generation_pages(generation_index_t generation)
             page_table[start].write_protected = 1;
 
             for (last = start + 1; last < last_free_page; last++) {
-                if ((page_table[last].allocated != BOXED_PAGE_FLAG)
-                    || (page_table[last].bytes_used == 0)
-                    || page_table[last].dont_move
-                    || (page_table[last].gen != generation))
+                if (!protect_page_p(last, generation))
                   break;
                 page_table[last].write_protected = 1;
             }
@@ -3722,165 +3830,22 @@ write_protect_generation_pages(generation_index_t generation)
 }
 
 #if !defined(LISP_FEATURE_X86) && !defined(LISP_FEATURE_X86_64)
-
 static void
-scavenge_control_stack()
+scavenge_control_stack(struct thread *th)
 {
     unsigned long control_stack_size;
 
     /* This is going to be a big problem when we try to port threads
      * to PPC... CLH */
-    struct thread *th = arch_os_get_current_thread();
     lispobj *control_stack =
         (lispobj *)(th->control_stack_start);
 
     control_stack_size = current_control_stack_pointer - control_stack;
     scavenge(control_stack, control_stack_size);
 }
-
-/* Scavenging Interrupt Contexts */
-
-static int boxed_registers[] = BOXED_REGISTERS;
-
-static void
-scavenge_interrupt_context(os_context_t * context)
-{
-    int i;
-
-#ifdef reg_LIP
-    unsigned long lip;
-    unsigned long lip_offset;
-    int lip_register_pair;
 #endif
-    unsigned long pc_code_offset;
 
-#ifdef ARCH_HAS_LINK_REGISTER
-    unsigned long lr_code_offset;
-#endif
-#ifdef ARCH_HAS_NPC_REGISTER
-    unsigned long npc_code_offset;
-#endif
-
-#ifdef reg_LIP
-    /* Find the LIP's register pair and calculate it's offset */
-    /* before we scavenge the context. */
-
-    /*
-     * I (RLT) think this is trying to find the boxed register that is
-     * closest to the LIP address, without going past it.  Usually, it's
-     * reg_CODE or reg_LRA.  But sometimes, nothing can be found.
-     */
-    lip = *os_context_register_addr(context, reg_LIP);
-    lip_offset = 0x7FFFFFFF;
-    lip_register_pair = -1;
-    for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
-        unsigned long reg;
-        long offset;
-        int index;
-
-        index = boxed_registers[i];
-        reg = *os_context_register_addr(context, index);
-        if ((reg & ~((1L<<N_LOWTAG_BITS)-1)) <= lip) {
-            offset = lip - reg;
-            if (offset < lip_offset) {
-                lip_offset = offset;
-                lip_register_pair = index;
-            }
-        }
-    }
-#endif /* reg_LIP */
-
-    /* Compute the PC's offset from the start of the CODE */
-    /* register. */
-    pc_code_offset = *os_context_pc_addr(context)
-        - *os_context_register_addr(context, reg_CODE);
-#ifdef ARCH_HAS_NPC_REGISTER
-    npc_code_offset = *os_context_npc_addr(context)
-        - *os_context_register_addr(context, reg_CODE);
-#endif /* ARCH_HAS_NPC_REGISTER */
-
-#ifdef ARCH_HAS_LINK_REGISTER
-    lr_code_offset =
-        *os_context_lr_addr(context) -
-        *os_context_register_addr(context, reg_CODE);
-#endif
-
-    /* Scanvenge all boxed registers in the context. */
-    for (i = 0; i < (sizeof(boxed_registers) / sizeof(int)); i++) {
-        int index;
-        lispobj foo;
-
-        index = boxed_registers[i];
-        foo = *os_context_register_addr(context, index);
-        scavenge(&foo, 1);
-        *os_context_register_addr(context, index) = foo;
-
-        scavenge((lispobj*) &(*os_context_register_addr(context, index)), 1);
-    }
-
-#ifdef reg_LIP
-    /* Fix the LIP */
-
-    /*
-     * But what happens if lip_register_pair is -1?
-     * *os_context_register_addr on Solaris (see
-     * solaris_register_address in solaris-os.c) will return
-     * &context->uc_mcontext.gregs[2]. But gregs[2] is REG_nPC. Is
-     * that what we really want? My guess is that that is not what we
-     * want, so if lip_register_pair is -1, we don't touch reg_LIP at
-     * all. But maybe it doesn't really matter if LIP is trashed?
-     */
-    if (lip_register_pair >= 0) {
-        *os_context_register_addr(context, reg_LIP) =
-            *os_context_register_addr(context, lip_register_pair)
-            + lip_offset;
-    }
-#endif /* reg_LIP */
-
-    /* Fix the PC if it was in from space */
-    if (from_space_p(*os_context_pc_addr(context)))
-        *os_context_pc_addr(context) =
-            *os_context_register_addr(context, reg_CODE) + pc_code_offset;
-
-#ifdef ARCH_HAS_LINK_REGISTER
-    /* Fix the LR ditto; important if we're being called from
-     * an assembly routine that expects to return using blr, otherwise
-     * harmless */
-    if (from_space_p(*os_context_lr_addr(context)))
-        *os_context_lr_addr(context) =
-            *os_context_register_addr(context, reg_CODE) + lr_code_offset;
-#endif
-
-#ifdef ARCH_HAS_NPC_REGISTER
-    if (from_space_p(*os_context_npc_addr(context)))
-        *os_context_npc_addr(context) =
-            *os_context_register_addr(context, reg_CODE) + npc_code_offset;
-#endif /* ARCH_HAS_NPC_REGISTER */
-}
-
-void
-scavenge_interrupt_contexts(void)
-{
-    int i, index;
-    os_context_t *context;
-
-    struct thread *th=arch_os_get_current_thread();
-
-    index = fixnum_value(SymbolValue(FREE_INTERRUPT_CONTEXT_INDEX,0));
-
-#if defined(DEBUG_PRINT_CONTEXT_INDEX)
-    printf("Number of active contexts: %d\n", index);
-#endif
-
-    for (i = 0; i < index; i++) {
-        context = th->interrupt_contexts[i];
-        scavenge_interrupt_context(context);
-    }
-}
-
-#endif
-
-#if defined(LISP_FEATURE_SB_THREAD)
+#if defined(LISP_FEATURE_SB_THREAD) && (defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64))
 static void
 preserve_context_registers (os_context_t *c)
 {
@@ -3931,9 +3896,8 @@ garbage_collect_generation(generation_index_t generation, int raise)
     unsigned long bytes_freed;
     page_index_t i;
     unsigned long static_space_size;
-#if defined(LISP_FEATURE_X86) || defined(LISP_FEATURE_X86_64)
     struct thread *th;
-#endif
+
     gc_assert(generation <= HIGHEST_NORMAL_GENERATION);
 
     /* The oldest generation can't be raised. */
@@ -4033,15 +3997,28 @@ garbage_collect_generation(generation_index_t generation, int raise)
             }
         }
     }
+#else
+    /* Non-x86oid systems don't have "conservative roots" as such, but
+     * the same mechanism is used for objects pinned for use by alien
+     * code. */
+    for_each_thread(th) {
+        lispobj pin_list = SymbolTlValue(PINNED_OBJECTS,th);
+        while (pin_list != NIL) {
+            struct cons *list_entry =
+                (struct cons *)native_pointer(pin_list);
+            preserve_pointer(list_entry->car);
+            pin_list = list_entry->cdr;
+        }
+    }
 #endif
 
-#ifdef QSHOW
+#if QSHOW
     if (gencgc_verbose > 1) {
         long num_dont_move_pages = count_dont_move_pages();
         fprintf(stderr,
                 "/non-movable pages due to conservative pointers = %d (%d bytes)\n",
                 num_dont_move_pages,
-                npage_bytes(num_dont_move_pages);
+                npage_bytes(num_dont_move_pages));
     }
 #endif
 
@@ -4052,8 +4029,18 @@ garbage_collect_generation(generation_index_t generation, int raise)
      * If not x86, we need to scavenge the interrupt context(s) and the
      * control stack.
      */
-    scavenge_interrupt_contexts();
-    scavenge_control_stack();
+    {
+        struct thread *th;
+        for_each_thread(th) {
+            scavenge_interrupt_contexts(th);
+            scavenge_control_stack(th);
+        }
+
+        /* Scrub the unscavenged control stack space, so that we can't run
+         * into any stale pointers in a later GC (this is done by the
+         * stop-for-gc handler in the other threads). */
+        scrub_control_stack();
+    }
 #endif
 
     /* Scavenge the Lisp functions of the interrupt handlers, taking
@@ -4178,8 +4165,9 @@ garbage_collect_generation(generation_index_t generation, int raise)
     generations[generation].alloc_large_unboxed_start_page = 0;
 
     if (generation >= verify_gens) {
-        if (gencgc_verbose)
+        if (gencgc_verbose) {
             SHOW("verifying");
+        }
         verify_gc();
         verify_dynamic_space();
     }
@@ -4208,8 +4196,7 @@ update_dynamic_space_free_pointer(void)
     page_index_t last_page = -1, i;
 
     for (i = 0; i < last_free_page; i++)
-        if ((page_table[i].allocated != FREE_PAGE_FLAG)
-            && (page_table[i].bytes_used != 0))
+        if (page_allocated_p(i) && (page_table[i].bytes_used != 0))
             last_page = i;
 
     last_free_page = last_page+1;
@@ -4224,15 +4211,15 @@ remap_free_pages (page_index_t from, page_index_t to)
     page_index_t first_page, last_page;
 
     for (first_page = from; first_page <= to; first_page++) {
-        if (page_table[first_page].allocated != FREE_PAGE_FLAG ||
-            page_table[first_page].need_to_zero == 0) {
+        if (page_allocated_p(first_page) ||
+            (page_table[first_page].need_to_zero == 0)) {
             continue;
         }
 
         last_page = first_page + 1;
-        while (page_table[last_page].allocated == FREE_PAGE_FLAG &&
-               last_page < to &&
-               page_table[last_page].need_to_zero == 1) {
+        while (page_free_p(last_page) &&
+               (last_page < to) &&
+               (page_table[last_page].need_to_zero == 1)) {
             last_page++;
         }
 
@@ -4291,7 +4278,7 @@ collect_garbage(generation_index_t last_gen)
     }
 
     if (gencgc_verbose > 1)
-        print_generation_stats(0);
+        print_generation_stats();
 
     do {
         /* Collect the generation. */
@@ -4302,7 +4289,7 @@ collect_garbage(generation_index_t last_gen)
         } else {
             raise =
                 (gen < last_gen)
-                || (generations[gen].num_gc >= generations[gen].trigger_age);
+                || (generations[gen].num_gc >= generations[gen].number_of_gcs_before_promotion);
         }
 
         if (gencgc_verbose > 1) {
@@ -4329,7 +4316,7 @@ collect_garbage(generation_index_t last_gen)
 
         if (gencgc_verbose > 1) {
             FSHOW((stderr, "GC of generation %d finished:\n", gen));
-            print_generation_stats(0);
+            print_generation_stats();
         }
 
         gen++;
@@ -4339,8 +4326,8 @@ collect_garbage(generation_index_t last_gen)
                      && raise
                      && (generations[gen].bytes_allocated
                          > generations[gen].gc_trigger)
-                     && (gen_av_mem_age(gen)
-                         > generations[gen].min_av_mem_age))));
+                     && (generation_average_age(gen)
+                         > generations[gen].minimum_age_before_gc))));
 
     /* Now if gen-1 was raised all generations before gen are empty.
      * If it wasn't raised then all generations before gen-1 are empty.
@@ -4408,12 +4395,13 @@ gc_free_heap(void)
 {
     page_index_t page;
 
-    if (gencgc_verbose > 1)
+    if (gencgc_verbose > 1) {
         SHOW("entering gc_free_heap");
+    }
 
     for (page = 0; page < page_table_pages; page++) {
         /* Skip free pages which should already be zero filled. */
-        if (page_table[page].allocated != FREE_PAGE_FLAG) {
+        if (page_allocated_p(page)) {
             void *page_start, *addr;
 
             /* Mark the page free. The other slots are assumed invalid
@@ -4447,7 +4435,7 @@ gc_free_heap(void)
             /* Double-check that the page is zero filled. */
             long *page_start;
             page_index_t i;
-            gc_assert(page_table[page].allocated == FREE_PAGE_FLAG);
+            gc_assert(page_free_p(page));
             gc_assert(page_table[page].bytes_used == 0);
             page_start = (long *)page_address(page);
             for (i=0; i<1024; i++) {
@@ -4474,7 +4462,7 @@ gc_free_heap(void)
     }
 
     if (gencgc_verbose > 1)
-        print_generation_stats(0);
+        print_generation_stats();
 
     /* Initialize gc_alloc(). */
     gc_alloc_generation = 0;
@@ -4543,8 +4531,8 @@ gc_init(void)
         generations[i].cum_sum_bytes_allocated = 0;
         /* the tune-able parameters */
         generations[i].bytes_consed_between_gc = 2000000;
-        generations[i].trigger_age = 1;
-        generations[i].min_av_mem_age = 0.75;
+        generations[i].number_of_gcs_before_promotion = 1;
+        generations[i].minimum_age_before_gc = 0.75;
         generations[i].lutexes = NULL;
     }
 
@@ -4568,21 +4556,26 @@ gencgc_pickup_dynamic(void)
     void *alloc_ptr = (void *)get_alloc_pointer();
     lispobj *prev=(lispobj *)page_address(page);
     generation_index_t gen = PSEUDO_STATIC_GENERATION;
-
     do {
         lispobj *first,*ptr= (lispobj *)page_address(page);
-        page_table[page].allocated = BOXED_PAGE_FLAG;
-        page_table[page].gen = gen;
-        page_table[page].bytes_used = PAGE_BYTES;
-        page_table[page].large_object = 0;
-        page_table[page].write_protected = 0;
-        page_table[page].write_protected_cleared = 0;
-        page_table[page].dont_move = 0;
-        page_table[page].need_to_zero = 1;
+
+        if (!gencgc_partial_pickup || page_allocated_p(page)) {
+          /* It is possible, though rare, for the saved page table
+           * to contain free pages below alloc_ptr. */
+          page_table[page].gen = gen;
+          page_table[page].bytes_used = PAGE_BYTES;
+          page_table[page].large_object = 0;
+          page_table[page].write_protected = 0;
+          page_table[page].write_protected_cleared = 0;
+          page_table[page].dont_move = 0;
+          page_table[page].need_to_zero = 1;
+        }
 
         if (!gencgc_partial_pickup) {
+            page_table[page].allocated = BOXED_PAGE_FLAG;
             first=gc_search_space(prev,(ptr+2)-prev,ptr);
-            if(ptr == first)  prev=ptr;
+            if(ptr == first)
+                prev=ptr;
             page_table[page].region_start_offset =
                 page_address(page) - (void *)prev;
         }
@@ -4610,8 +4603,6 @@ gc_initialize_pointers(void)
 {
     gencgc_pickup_dynamic();
 }
-
-
 \f
 
 /* alloc(..) is the external interface for memory allocation. It
@@ -4626,16 +4617,10 @@ gc_initialize_pointers(void)
  * The check for a GC trigger is only performed when the current
  * region is full, so in most cases it's not needed. */
 
-lispobj *
-alloc(long nbytes)
+static inline lispobj *
+general_alloc_internal(long nbytes, int page_type_flag, struct alloc_region *region,
+                       struct thread *thread)
 {
-    struct thread *thread=arch_os_get_current_thread();
-    struct alloc_region *region=
-#ifdef LISP_FEATURE_SB_THREAD
-        thread ? &(thread->alloc_region) : &boxed_region;
-#else
-        &boxed_region;
-#endif
 #ifndef LISP_FEATURE_WIN32
     lispobj alloc_signal;
 #endif
@@ -4648,25 +4633,8 @@ alloc(long nbytes)
     gc_assert((((unsigned long)region->free_pointer & LOWTAG_MASK) == 0)
               && ((nbytes & LOWTAG_MASK) == 0));
 
-#if 0
-    if(all_threads)
-        /* there are a few places in the C code that allocate data in the
-         * heap before Lisp starts.  This is before interrupts are enabled,
-         * so we don't need to check for pseudo-atomic */
-#ifdef LISP_FEATURE_SB_THREAD
-        if(!get_psuedo_atomic_atomic(th)) {
-            register u32 fs;
-            fprintf(stderr, "fatal error in thread 0x%x, tid=%ld\n",
-                    th,th->os_thread);
-            __asm__("movl %fs,%0" : "=r" (fs)  : );
-            fprintf(stderr, "fs is %x, th->tls_cookie=%x \n",
-                    debug_get_fs(),th->tls_cookie);
-            lose("If you see this message before 2004.01.31, mail details to sbcl-devel\n");
-        }
-#else
-    gc_assert(get_pseudo_atomic_atomic(th));
-#endif
-#endif
+    /* Must be inside a PA section. */
+    gc_assert(get_pseudo_atomic_atomic(thread));
 
     /* maybe we can do this quickly ... */
     new_free_pointer = region->free_pointer + nbytes;
@@ -4676,11 +4644,10 @@ alloc(long nbytes)
         return(new_obj);        /* yup */
     }
 
-    /* we have to go the long way around, it seems.  Check whether
-     * we should GC in the near future
+    /* we have to go the long way around, it seems. Check whether we
+     * should GC in the near future
      */
     if (auto_gc_trigger && bytes_allocated > auto_gc_trigger) {
-        gc_assert(get_pseudo_atomic_atomic(thread));
         /* 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. */
@@ -4688,22 +4655,31 @@ alloc(long nbytes)
             /* set things up so that GC happens when we finish the PA
              * section */
             SetSymbolValue(GC_PENDING,T,thread);
-            if (SymbolValue(GC_INHIBIT,thread) == NIL)
-              set_pseudo_atomic_interrupted(thread);
+            if (SymbolValue(GC_INHIBIT,thread) == NIL) {
+                set_pseudo_atomic_interrupted(thread);
+#ifdef LISP_FEATURE_PPC
+                /* PPC calls alloc() from a trap or from pa_alloc(),
+                 * look up the most context if it's from a trap. */
+                {
+                    os_context_t *context =
+                        thread->interrupt_data->allocation_trap_context;
+                    maybe_save_gc_mask_and_block_deferrables
+                        (context ? os_context_sigmask_addr(context) : NULL);
+                }
+#else
+                maybe_save_gc_mask_and_block_deferrables(NULL);
+#endif
+            }
         }
     }
-    new_obj = gc_alloc_with_region(nbytes,0,region,0);
+    new_obj = gc_alloc_with_region(nbytes, page_type_flag, region, 0);
 
 #ifndef LISP_FEATURE_WIN32
     alloc_signal = SymbolValue(ALLOC_SIGNAL,thread);
     if ((alloc_signal & FIXNUM_TAG_MASK) == 0) {
         if ((signed long) alloc_signal <= 0) {
             SetSymbolValue(ALLOC_SIGNAL, T, thread);
-#ifdef LISP_FEATURE_SB_THREAD
-            kill_thread_safely(thread->os_thread, SIGPROF);
-#else
             raise(SIGPROF);
-#endif
         } else {
             SetSymbolValue(ALLOC_SIGNAL,
                            alloc_signal - (1 << N_FIXNUM_TAG_BITS),
@@ -4714,12 +4690,43 @@ alloc(long nbytes)
 
     return (new_obj);
 }
+
+lispobj *
+general_alloc(long nbytes, int page_type_flag)
+{
+    struct thread *thread = arch_os_get_current_thread();
+    /* Select correct region, and call general_alloc_internal with it.
+     * For other then boxed allocation we must lock first, since the
+     * region is shared. */
+    if (BOXED_PAGE_FLAG & page_type_flag) {
+#ifdef LISP_FEATURE_SB_THREAD
+        struct alloc_region *region = (thread ? &(thread->alloc_region) : &boxed_region);
+#else
+        struct alloc_region *region = &boxed_region;
+#endif
+        return general_alloc_internal(nbytes, page_type_flag, region, thread);
+    } else if (UNBOXED_PAGE_FLAG == page_type_flag) {
+        lispobj * obj;
+        gc_assert(0 == thread_mutex_lock(&allocation_lock));
+        obj = general_alloc_internal(nbytes, page_type_flag, &unboxed_region, thread);
+        gc_assert(0 == thread_mutex_unlock(&allocation_lock));
+        return obj;
+    } else {
+        lose("bad page type flag: %d", page_type_flag);
+    }
+}
+
+lispobj *
+alloc(long nbytes)
+{
+    gc_assert(get_pseudo_atomic_atomic(arch_os_get_current_thread()));
+    return general_alloc(nbytes, BOXED_PAGE_FLAG);
+}
 \f
 /*
  * shared support for the OS-dependent signal handlers which
  * catch GENCGC-related write-protect violations
  */
-
 void unhandled_sigmemoryfault(void* addr);
 
 /* Depending on which OS we're running under, different signals might
@@ -4737,7 +4744,7 @@ gencgc_handle_wp_violation(void* fault_addr)
 {
     page_index_t page_index = find_page_index(fault_addr);
 
-#ifdef QSHOW_SIGNALS
+#if QSHOW_SIGNALS
     FSHOW((stderr, "heap WP violation? fault_addr=%x, page_index=%d\n",
            fault_addr, page_index));
 #endif
@@ -4753,6 +4760,9 @@ gencgc_handle_wp_violation(void* fault_addr)
         return 0;
 
     } else {
+        int ret;
+        ret = thread_mutex_lock(&free_pages_lock);
+        gc_assert(ret == 0);
         if (page_table[page_index].write_protected) {
             /* Unprotect the page. */
             os_protect(page_address(page_index), PAGE_BYTES, OS_VM_PROT_ALL);
@@ -4770,6 +4780,8 @@ gencgc_handle_wp_violation(void* fault_addr)
                      page_index, boxed_region.first_page,
                      boxed_region.last_page);
         }
+        ret = thread_mutex_unlock(&free_pages_lock);
+        gc_assert(ret == 0);
         /* Don't worry, we can handle it. */
         return 1;
     }
@@ -4787,9 +4799,9 @@ void gc_alloc_update_all_page_tables(void)
     /* Flush the alloc regions updating the tables. */
     struct thread *th;
     for_each_thread(th)
-        gc_alloc_update_page_tables(0, &th->alloc_region);
-    gc_alloc_update_page_tables(1, &unboxed_region);
-    gc_alloc_update_page_tables(0, &boxed_region);
+        gc_alloc_update_page_tables(BOXED_PAGE_FLAG, &th->alloc_region);
+    gc_alloc_update_page_tables(UNBOXED_PAGE_FLAG, &unboxed_region);
+    gc_alloc_update_page_tables(BOXED_PAGE_FLAG, &boxed_region);
 }
 
 void
@@ -4808,7 +4820,7 @@ zero_all_free_pages()
     page_index_t i;
 
     for (i = 0; i < last_free_page; i++) {
-        if (page_table[i].allocated == FREE_PAGE_FLAG) {
+        if (page_free_p(i)) {
 #ifdef READ_PROTECT_FREE_PAGES
             os_protect(page_address(i),
                        PAGE_BYTES,