From 96e5109430a5e82bf082244ecc4942d9e93be19a Mon Sep 17 00:00:00 2001
From: Alan Cox <alc@FreeBSD.org>
Date: Sun, 14 Aug 2005 20:02:50 +0000
Subject: Simplify the page table page reference counting by pmap_enter()'s
 change of mapping case.

Eliminate a stale comment from pmap_enter().

Reviewed by:	tegge
---
 sys/amd64/amd64/pmap.c | 17 ++++++++---------
 sys/i386/i386/pmap.c   | 14 +++++++-------
 2 files changed, 15 insertions(+), 16 deletions(-)

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index e45f2561e137..d9ead4ca70ce 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -1820,7 +1820,6 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
 	vm_paddr_t pa;
 	register pt_entry_t *pte;
 	vm_paddr_t opa;
-	pd_entry_t ptepde;
 	pt_entry_t origpte, newpte;
 	vm_page_t mpte, om;
 
@@ -1855,7 +1854,7 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
 	}
 #endif
 
-	pte = pmap_pte_pde(pmap, va, &ptepde);
+	pte = pmap_pte(pmap, va);
 
 	/*
 	 * Page Directory table entry not valid, we need a new PT page
@@ -1915,23 +1914,23 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
 	 * handle validating new mapping.
 	 */
 	if (opa) {
-		int err;
 		if (origpte & PG_W)
 			pmap->pm_stats.wired_count--;
 		if (origpte & PG_MANAGED) {
 			om = PHYS_TO_VM_PAGE(opa);
 			pmap_remove_entry(pmap, om, va);
 		}
-		err = pmap_unuse_pt(pmap, va, ptepde);
-		if (err)
-			panic("pmap_enter: pte vanished, va: 0x%lx", va);
+		if (mpte != NULL) {
+			mpte->wire_count--;
+			KASSERT(mpte->wire_count > 0,
+			    ("pmap_enter: missing reference to page table page,"
+			     " va: 0x%lx", va));
+		}
 	} else
 		pmap->pm_stats.resident_count++;
 
 	/*
-	 * Enter on the PV list if part of our managed memory. Note that we
-	 * raise IPL while manipulating pv_table since pmap_enter can be
-	 * called at interrupt time.
+	 * Enter on the PV list if part of our managed memory.
 	 */
 	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0) {
 		pmap_insert_entry(pmap, va, m);
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index e5ad5fa312b0..84e5bd5b08c9 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -1954,23 +1954,23 @@ pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
 	 * handle validating new mapping.
 	 */
 	if (opa) {
-		int err;
 		if (origpte & PG_W)
 			pmap->pm_stats.wired_count--;
 		if (origpte & PG_MANAGED) {
 			om = PHYS_TO_VM_PAGE(opa);
 			pmap_remove_entry(pmap, om, va);
 		}
-		err = pmap_unuse_pt(pmap, va);
-		if (err)
-			panic("pmap_enter: pte vanished, va: 0x%x", va);
+		if (mpte != NULL) {
+			mpte->wire_count--;
+			KASSERT(mpte->wire_count > 0,
+			    ("pmap_enter: missing reference to page table page,"
+			     " va: 0x%x", va));
+		}
 	} else
 		pmap->pm_stats.resident_count++;
 
 	/*
-	 * Enter on the PV list if part of our managed memory. Note that we
-	 * raise IPL while manipulating pv_table since pmap_enter can be
-	 * called at interrupt time.
+	 * Enter on the PV list if part of our managed memory.
 	 */
 	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0) {
 		pmap_insert_entry(pmap, va, m);
-- 
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