[src/trunk]: src/sys/arch/x86/x86 zero out the unused parts of direct-map pag...

[chs <chs%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/a216fe74544b
branches:  trunk
changeset: 773648:a216fe74544b
user:      chs <chs%NetBSD.org@localhost>
date:      Sat Feb 11 18:59:41 2012 +0000

description:
zero out the unused parts of direct-map page-table pages.
these seem to cause problems even though they aren't actually referenced,
probably due to speculative execution.
fixes PR 45892.

diffstat:

 sys/arch/x86/x86/pmap.c |  26 +++++++++++++++++++++-----
 1 files changed, 21 insertions(+), 5 deletions(-)

diffs (63 lines):

diff -r 9e8b21b487cc -r a216fe74544b sys/arch/x86/x86/pmap.c
--- a/sys/arch/x86/x86/pmap.c   Sat Feb 11 18:22:58 2012 +0000
+++ b/sys/arch/x86/x86/pmap.c   Sat Feb 11 18:59:41 2012 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.c,v 1.163 2012/02/01 18:55:32 cherry Exp $        */
+/*     $NetBSD: pmap.c,v 1.164 2012/02/11 18:59:41 chs Exp $   */
 
 /*-
  * Copyright (c) 2008, 2010 The NetBSD Foundation, Inc.
@@ -171,7 +171,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.163 2012/02/01 18:55:32 cherry Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.164 2012/02/11 18:59:41 chs Exp $");
 
 #include "opt_user_ldt.h"
 #include "opt_lockdebug.h"
@@ -1188,7 +1188,7 @@
 #ifdef __HAVE_DIRECT_MAP
        phys_ram_seg_t *mc;
        long ndmpdp;
-       paddr_t dmpd, dmpdp, pdp;
+       paddr_t lastpa, dmpd, dmpdp, pdp;
        vaddr_t tmpva;
 #endif
 
@@ -1331,10 +1331,19 @@
         * otherwise use 2MB pages.
         */
 
-       mc = &mem_clusters[mem_cluster_cnt - 1];
-       ndmpdp = (mc->start + mc->size + NBPD_L3 - 1) >> L3_SHIFT;
+       lastpa = 0;
+       for (i = 0; i < mem_cluster_cnt; i++) {
+               mc = &mem_clusters[i];
+               lastpa = MAX(lastpa, mc->start + mc->size);
+       }
+
+       ndmpdp = (lastpa + NBPD_L3 - 1) >> L3_SHIFT;
        dmpdp = avail_start;    avail_start += PAGE_SIZE;
 
+       *pte = dmpdp | PG_V | PG_RW;
+       pmap_update_pg(tmpva);
+       memset((void *)tmpva, 0, PAGE_SIZE);
+
        if (cpu_feature[2] & CPUID_P1GB) {
                for (i = 0; i < ndmpdp; i++) {
                        pdp = (paddr_t)&(((pd_entry_t *)dmpdp)[i]);
@@ -1348,6 +1357,13 @@
        } else {
                dmpd = avail_start;     avail_start += ndmpdp * PAGE_SIZE;
 
+               for (i = 0; i < ndmpdp; i++) {
+                       pdp = dmpd + i * PAGE_SIZE;
+                       *pte = (pdp & PG_FRAME) | PG_V | PG_RW;
+                       pmap_update_pg(tmpva);
+
+                       memset((void *)tmpva, 0, PAGE_SIZE);
+               }
                for (i = 0; i < NPDPG * ndmpdp; i++) {
                        pdp = (paddr_t)&(((pd_entry_t *)dmpd)[i]);
                        *pte = (pdp & PG_FRAME) | PG_V | PG_RW;