From e468d4c8d983b8b14e4bbba16f20a2780a5146af Mon Sep 17 00:00:00 2001
From: thorpej <thorpej@NetBSD.org>
Date: Fri, 9 Apr 1999 00:38:10 +0000
Subject: [PATCH] Fix a bug in TBI optimization uncovered by the "access_type"
 changes.  Thanks to Bernd Ernesti for providing crash dumps to Charles Hannum
 who tracked it down.

---
 sys/arch/alpha/alpha/pmap.c  | 25 +++++++++++++------------
 sys/arch/alpha/include/pte.h |  8 +++-----
 2 files changed, 16 insertions(+), 17 deletions(-)

diff --git a/sys/arch/alpha/alpha/pmap.c b/sys/arch/alpha/alpha/pmap.c
index dd51da46e8e7..3753343a559c 100644
--- a/sys/arch/alpha/alpha/pmap.c
+++ b/sys/arch/alpha/alpha/pmap.c
@@ -1,4 +1,4 @@
-/* $NetBSD: pmap.c,v 1.88 1999/03/29 05:31:24 mycroft Exp $ */
+/* $NetBSD: pmap.c,v 1.89 1999/04/09 00:38:10 thorpej Exp $ */
 
 /*-
  * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
@@ -155,7 +155,7 @@
 
 #include <sys/cdefs.h>			/* RCS ID & Copyright macro defns */
 
-__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.88 1999/03/29 05:31:24 mycroft Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pmap.c,v 1.89 1999/04/09 00:38:10 thorpej Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -1569,7 +1569,7 @@ pmap_enter(pmap, va, pa, prot, wired, access_type)
 	vm_prot_t access_type;
 {
 	boolean_t managed;
-	pt_entry_t *pte, npte;
+	pt_entry_t *pte, npte, opte;
 	paddr_t opa;
 	boolean_t tflush = TRUE;
 	boolean_t hadasm = FALSE;	/* XXX gcc -Wuninitialized */
@@ -1663,6 +1663,9 @@ pmap_enter(pmap, va, pa, prot, wired, access_type)
 		pte = pmap_l3pte(pmap, va, l2pte);
 	}
 
+	/* Remember all of the old PTE; used for TBI check later. */
+	opte = *pte;
+
 	/*
 	 * Check to see if the old mapping is valid.  If not, validate the
 	 * new one immediately.
@@ -1714,15 +1717,6 @@ pmap_enter(pmap, va, pa, prot, wired, access_type)
 				pmap->pm_stats.wired_count--;
 		}
 
-		/*
-		 * Check to see if the PALcode portion of the
-		 * PTE is the same.  If so, no TLB invalidation
-		 * is necessary.
-		 */
-		if (PG_PALCODE(pmap_pte_prot(pte)) ==
-		    PG_PALCODE(pte_prot(pmap, prot)))
-			tflush = FALSE;
-
 		/*
 		 * Set the PTE.
 		 */
@@ -1802,6 +1796,13 @@ pmap_enter(pmap, va, pa, prot, wired, access_type)
 		printf("pmap_enter: new pte = 0x%lx\n", npte);
 #endif
 
+	/*
+	 * If the PALcode portion of the new PTE is the same as the
+	 * old PTE, no TBI is necessary.
+	 */
+	if (PG_PALCODE(opte) == PG_PALCODE(npte))
+		tflush = FALSE;
+
 	/*
 	 * Set the new PTE.
 	 */
diff --git a/sys/arch/alpha/include/pte.h b/sys/arch/alpha/include/pte.h
index c856364dda7c..63c300f6a8c1 100644
--- a/sys/arch/alpha/include/pte.h
+++ b/sys/arch/alpha/include/pte.h
@@ -1,4 +1,4 @@
-/* $NetBSD: pte.h,v 1.25 1998/08/14 16:50:03 thorpej Exp $ */
+/* $NetBSD: pte.h,v 1.26 1999/04/09 00:38:11 thorpej Exp $ */
 
 /*-
  * Copyright (c) 1998 The NetBSD Foundation, Inc.
@@ -110,11 +110,9 @@ typedef	alpha_pt_entry_t	pt_entry_t;
 
 /*
  * These are the PALcode PTE bits that we care about when checking to see
- * if a PTE has changed in such a way as to require a TBI.  We don't care
- * about the FOx bits because we always remember the state of those bits and
- * set them to mirror what the TB has (they are used for mod/ref emulation).
+ * if a PTE has changed in such a way as to require a TBI.
  */
-#define	PG_PALCODE(x)	((x) & (ALPHA_PTE_PALCODE & ~(PG_FOR|PG_FOW|PG_FOE)))
+#define	PG_PALCODE(x)	((x) & ALPHA_PTE_PALCODE)
 
 #if defined(_KERNEL) || defined(__KVM_ALPHA_PRIVATE)
 #define	NPTEPG_SHIFT	(PAGE_SHIFT - PTESHIFT)