[src/trunk]: src/sys/arch/powerpc/ibm4xx In ppc4xx_tlb_find_victim(), mark ke...

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

details:   https://anonhg.NetBSD.org/src/rev/1d2a05ce437a
branches:  trunk
changeset: 745020:1d2a05ce437a
user:      rin <rin%NetBSD.org@localhost>
date:      Fri Feb 21 13:16:16 2020 +0000

description:
In ppc4xx_tlb_find_victim(), mark kernel stack page TLBF_REF instead of
TLBF_USED. This should be originally intended behavior of this code
segment, because

- TLBF_USED is already checked just before, so marking this page
  TLBF_USED is no-op.
- TLBF_REF flag exempts that page from being flushed from TLB in next
  scan, when kernel stack may be still there with high probability.

diffstat:

 sys/arch/powerpc/ibm4xx/pmap.c |  6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diffs (27 lines):

diff -r 9986fdbbdfd1 -r 1d2a05ce437a sys/arch/powerpc/ibm4xx/pmap.c
--- a/sys/arch/powerpc/ibm4xx/pmap.c    Fri Feb 21 13:15:54 2020 +0000
+++ b/sys/arch/powerpc/ibm4xx/pmap.c    Fri Feb 21 13:16:16 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pmap.c,v 1.79 2020/02/20 05:34:37 rin Exp $    */
+/*     $NetBSD: pmap.c,v 1.80 2020/02/21 13:16:16 rin Exp $    */
 
 /*
  * Copyright 2001 Wasabi Systems, Inc.
@@ -67,7 +67,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.79 2020/02/20 05:34:37 rin Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.80 2020/02/21 13:16:16 rin Exp $");
 
 #include <sys/param.h>
 #include <sys/cpu.h>
@@ -1276,7 +1276,7 @@
                            (tlb_info[tlbnext].ti_ctx == KERNEL_PID) &&
                             (flags & TLBF_USED)) {
                                /* Kernel stack page */
-                               flags |= TLBF_USED;
+                               flags |= TLBF_REF;
                                tlb_info[tlbnext].ti_flags = flags;
                        } else {
                                /* Found it! */