From: Ivan Maidanski <ivmai@mail.ru>
Date: Fri, 23 Sep 2016 06:39:18 +0000 (+0300)
Subject: Fix page calculation in checksums
X-Git-Tag: v8.0.0~1144
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6837b48ce6e0593cb84683cbb65f94648a6341b7;p=gc

Fix page calculation in checksums

While consistent use of rounding mode for computing GC_faulted entries
is ok, the proper way of getting page number of an address is just to
clear the lowest bits of the latter.

* checksums.c (GC_record_fault, GC_was_faulted): Do not round-up when
computing page.
* checksums.c (GC_record_fault): Add assertion that GC_page_size is
initialized.
---

diff --git a/checksums.c b/checksums.c
index f0f902a3..c0ecebea 100644
--- a/checksums.c
+++ b/checksums.c
@@ -41,8 +41,9 @@ STATIC size_t GC_n_faulted = 0;
 
 void GC_record_fault(struct hblk * h)
 {
-    word page = ROUNDUP_PAGESIZE((word)h);
+    word page = (word)h & ~(GC_page_size - 1);
 
+    GC_ASSERT(GC_page_size != 0);
     if (GC_n_faulted >= NSUMS) ABORT("write fault log overflowed");
     GC_faulted[GC_n_faulted++] = page;
 }
@@ -50,7 +51,7 @@ void GC_record_fault(struct hblk * h)
 STATIC GC_bool GC_was_faulted(struct hblk *h)
 {
     size_t i;
-    word page = ROUNDUP_PAGESIZE((word)h);
+    word page = (word)h & ~(GC_page_size - 1);
 
     for (i = 0; i < GC_n_faulted; ++i) {
         if (GC_faulted[i] == page) return TRUE;