From 68ed7473eb69ad894551afe2a78f0cc99af6f82e Mon Sep 17 00:00:00 2001
From: hboehm <hboehm>
Date: Sat, 20 Jun 2009 20:24:43 +0000
Subject: 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.
---
 checksums.c | 47 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 41 insertions(+), 6 deletions(-)

(limited to 'checksums.c')

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
-- 
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