2009-06-20 Hans Boehm <Hans.Boehm@hp.com>

	* allchblk.c (GC_allochblk_nth): Add assertion.
	* checksums.c: Add GC_record_fault, GC_was_faulted,
	CC_n_faulted_dirty_errors.
	(GC_check_dirty): Remove register declarations, print
	dirty bit errors on faulted pages.
	* os_dep.c (GC_write_fault_handler): Call GC_record_fault().
	* os_dep.c (GC_remove_protection): Compute index correctly.

4 files changed, 63 insertions, 7 deletions

diff --git a/ChangeLog b/ChangeLog
index 248bba41..f3eaef21 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2009-06-20  Hans Boehm <Hans.Boehm@hp.com>
+	
+	* allchblk.c (GC_allochblk_nth): Add assertion.
+	* checksums.c: Add GC_record_fault, GC_was_faulted,
+	CC_n_faulted_dirty_errors.
+	(GC_check_dirty): Remove register declarations, print
+	dirty bit errors on faulted pages.
+	* os_dep.c (GC_write_fault_handler): Call GC_record_fault().
+	* os_dep.c (GC_remove_protection): Compute index correctly.
+
 2009-06-12  Hans Boehm <Hans.Boehm@hp.com>
 	
 	* include/gc_version.h, configure.ac, doc/README:
diff --git a/allchblk.c b/allchblk.c
index 946f9711..b723a7f6 100644
--- a/allchblk.c
+++ b/allchblk.c
@@ -787,6 +787,9 @@ GC_allochblk_nth(size_t sz, int kind, unsigned flags, int n, GC_bool may_split)
 
     /* Notify virtual dirty bit implementation that we are about to write.  */
     /* Ensure that pointerfree objects are not protected if it's avoidable. */
+    /* This also ensures that newly allocated blocks are treated as dirty.  */
+    /* Necessary since we don't protect free blocks.			    */
+	GC_ASSERT((size_needed & (HBLKSIZE-1)) == 0);
     	GC_remove_protection(hbp, divHBLKSZ(size_needed),
 			     (hhdr -> hb_descr == 0) /* pointer-free */);
         
diff --git a/checksums.c b/checksums.c
index 91f3b282..275026d5 100644
--- a/checksums.c
+++ b/checksums.c
@@ -34,6 +34,33 @@ typedef struct {
 
 page_entry GC_sums [NSUMS];
 
+STATIC word GC_faulted[NSUMS];	/* Record of pages on which we saw a write */
+				/* fault.				   */
+STATIC size_t GC_n_faulted = 0;
+
+void GC_record_fault(struct hblk * h)
+{
+    word page = (word)h;
+
+    page += GC_page_size - 1;
+    page &= ~(GC_page_size - 1);
+    if (GC_n_faulted >= NSUMS) ABORT("write fault log overflowed");
+    GC_faulted[GC_n_faulted++] = page;
+}
+
+STATIC GC_bool GC_was_faulted(struct hblk *h)
+{
+    size_t i;
+    word page = (word)h;
+
+    page += GC_page_size - 1;
+    page &= ~(GC_page_size - 1);
+    for (i = 0; i < GC_n_faulted; ++i) {
+	if (GC_faulted[i] == page) return TRUE;
+    }
+    return FALSE;
+}
+
 STATIC word GC_checksum(struct hblk *h)
 {
     register word *p = (word *)h;
@@ -64,6 +91,7 @@ STATIC GC_bool GC_on_free_list(struct hblk *h)
 # endif
  
 int GC_n_dirty_errors;
+int GC_n_faulted_dirty_errors;
 int GC_n_changed_errors;
 int GC_n_clean;
 int GC_n_dirty;
@@ -96,7 +124,9 @@ STATIC void GC_update_check_page(struct hblk *h, int index)
 	&& hhdr != 0 && hhdr -> hb_descr != 0 /* may contain pointers */
 	&& pe -> old_sum != pe -> new_sum) {
     	if (!GC_page_was_dirty(h) || !GC_page_was_ever_dirty(h)) {
+	    GC_bool was_faulted = GC_was_faulted(h);
     	    /* Set breakpoint here */GC_n_dirty_errors++;
+	    if (was_faulted) GC_n_faulted_dirty_errors++;
     	}
 #	ifdef STUBBORN_ALLOC
     	  if (!HBLK_IS_FREE(hhdr)
@@ -144,14 +174,15 @@ STATIC void GC_check_blocks(void)
 /* Should be called immediately after GC_read_dirty and GC_read_changed. */
 void GC_check_dirty(void)
 {
-    register int index;
-    register unsigned i;
-    register struct hblk *h;
-    register ptr_t start;
+    int index;
+    unsigned i;
+    struct hblk *h;
+    ptr_t start;
     
     GC_check_blocks();
     
     GC_n_dirty_errors = 0;
+    GC_n_faulted_dirty_errors = 0;
     GC_n_changed_errors = 0;
     GC_n_clean = 0;
     GC_n_dirty = 0;
@@ -171,8 +202,8 @@ out:
     GC_printf("Checked %lu clean and %lu dirty pages\n",
     	      (unsigned long) GC_n_clean, (unsigned long) GC_n_dirty);
     if (GC_n_dirty_errors > 0) {
-        GC_printf("Found %lu dirty bit errors\n",
-        	  (unsigned long)GC_n_dirty_errors);
+        GC_printf("Found %d dirty bit errors (%d were faulted)\n",
+        	  GC_n_dirty_errors, GC_n_faulted_dirty_errors);
     }
     if (GC_n_changed_errors > 0) {
     	GC_printf("Found %lu changed bit errors\n",
@@ -183,6 +214,10 @@ out:
 	    "Also expect 1 per thread currently allocating a stubborn obj.\n");
 #	endif
     }
+    for (i = 0; i < GC_n_faulted; ++i) {
+        GC_faulted[i] = 0; /* Don't expose block pointers to GC */
+    }
+    GC_n_faulted = 0;
 }
 
 # else
diff --git a/os_dep.c b/os_dep.c
index e3b98b36..bc41216b 100644
--- a/os_dep.c
+++ b/os_dep.c
@@ -2639,6 +2639,11 @@ STATIC GC_bool GC_old_segv_handler_used_si;
 	set_pht_entry_from_index(db, index)
 #endif /* !THREADS */
 
+#ifdef CHECKSUMS
+  void GC_record_fault(struct hblk * h);
+	/* From checksums.c */
+#endif
+
 #if !defined(DARWIN)
 #   include <errno.h>
 #   if defined(FREEBSD)
@@ -2696,6 +2701,9 @@ STATIC GC_bool GC_old_segv_handler_used_si;
         register struct hblk * h =
         		(struct hblk *)((word)addr & ~(GC_page_size-1));
         GC_bool in_allocd_block;
+#	ifdef CHECKSUMS
+	  GC_record_fault(h);
+#	endif /* CHECKSUMS */
         
 #	ifdef SUNOS5SIGS
 	    /* Address is only within the correct physical page.	*/
@@ -2814,7 +2822,7 @@ void GC_remove_protection(struct hblk *h, word nblocks, GC_bool is_ptrfree)
 	return;
     }
     for (current = h_trunc; current < h_end; ++current) {
-        size_t index = PHT_HASH(h_trunc);
+        size_t index = PHT_HASH(current);
         if (!is_ptrfree || current < h || current >= h + nblocks) {
             async_set_pht_entry_from_index(GC_dirty_pages, index);
         }