From f0337456d9cd24e1649d4d85f5324c8d8bb8ebd6 Mon Sep 17 00:00:00 2001
From: alc <alc@FreeBSD.org>
Date: Tue, 18 Jul 2006 03:17:12 +0000
Subject: MFamd64  pmap_clear_ptes() is already convoluted.  This will worsen
 with the  implementation of superpages.  Eliminate it and add
 pmap_clear_write().

There are no functional changes.  Checked by: md5
---
 sys/i386/i386/pmap.c | 105 +++++++++++++++++++++++++++++++++------------------
 1 file changed, 69 insertions(+), 36 deletions(-)

(limited to 'sys')

diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index 24ae059..d8d5f61 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -266,7 +266,7 @@ static struct mtx PMAP2mutex;
 
 static void	free_pv_entry(pmap_t pmap, pv_entry_t pv);
 static pv_entry_t get_pv_entry(pmap_t locked_pmap, int try);
-static void	pmap_clear_ptes(vm_page_t m, int bit);
+static void	pmap_clear_write(vm_page_t m);
 
 static vm_page_t pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va,
     vm_page_t m, vm_prot_t prot, vm_page_t mpte);
@@ -3064,55 +3064,42 @@ pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
 }
 
 /*
- *	Clear the given bit in each of the given page's ptes.  The bit is
- *	expressed as a 32-bit mask.  Consequently, if the pte is 64 bits in
- *	size, only a bit within the least significant 32 can be cleared.
+ * Clear the write and modified bits in each of the given page's mappings.
  */
 static __inline void
-pmap_clear_ptes(vm_page_t m, int bit)
+pmap_clear_write(vm_page_t m)
 {
 	pv_entry_t pv;
 	pmap_t pmap;
-	pt_entry_t pbits, *pte;
+	pt_entry_t oldpte, *pte;
 
-	if ((m->flags & PG_FICTITIOUS) ||
-	    (bit == PG_RW && (m->flags & PG_WRITEABLE) == 0))
+	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
+	if ((m->flags & PG_FICTITIOUS) != 0 ||
+	    (m->flags & PG_WRITEABLE) == 0)
 		return;
-
 	sched_pin();
-	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
-	/*
-	 * Loop over all current mappings setting/clearing as appropos If
-	 * setting RO do we need to clear the VAC?
-	 */
 	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
 		pmap = PV_PMAP(pv);
 		PMAP_LOCK(pmap);
 		pte = pmap_pte_quick(pmap, pv->pv_va);
 retry:
-		pbits = *pte;
-		if (pbits & bit) {
-			if (bit == PG_RW) {
-				/*
-				 * Regardless of whether a pte is 32 or 64 bits
-				 * in size, PG_RW and PG_M are among the least
-				 * significant 32 bits.
-				 */
-				if (!atomic_cmpset_int((u_int *)pte, pbits,
-				    pbits & ~(PG_RW | PG_M)))
-					goto retry;
-				if (pbits & PG_M) {
-					vm_page_dirty(m);
-				}
-			} else {
-				atomic_clear_int((u_int *)pte, bit);
-			}
+		oldpte = *pte;
+		if ((oldpte & PG_RW) != 0) {
+			/*
+			 * Regardless of whether a pte is 32 or 64 bits
+			 * in size, PG_RW and PG_M are among the least
+			 * significant 32 bits.
+			 */
+			if (!atomic_cmpset_int((u_int *)pte, oldpte,
+			    oldpte & ~(PG_RW | PG_M)))
+				goto retry;
+			if ((oldpte & PG_M) != 0)
+				vm_page_dirty(m);
 			pmap_invalidate_page(pmap, pv->pv_va);
 		}
 		PMAP_UNLOCK(pmap);
 	}
-	if (bit == PG_RW)
-		vm_page_flag_clear(m, PG_WRITEABLE);
+	vm_page_flag_clear(m, PG_WRITEABLE);
 	sched_unpin();
 }
 
@@ -3126,7 +3113,7 @@ pmap_page_protect(vm_page_t m, vm_prot_t prot)
 {
 	if ((prot & VM_PROT_WRITE) == 0) {
 		if (prot & (VM_PROT_READ | VM_PROT_EXECUTE)) {
-			pmap_clear_ptes(m, PG_RW);
+			pmap_clear_write(m);
 		} else {
 			pmap_remove_all(m);
 		}
@@ -3186,7 +3173,30 @@ pmap_ts_referenced(vm_page_t m)
 void
 pmap_clear_modify(vm_page_t m)
 {
-	pmap_clear_ptes(m, PG_M);
+	pv_entry_t pv;
+	pmap_t pmap;
+	pt_entry_t *pte;
+
+	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
+	if ((m->flags & PG_FICTITIOUS) != 0)
+		return;
+	sched_pin();
+	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
+		pmap = PV_PMAP(pv);
+		PMAP_LOCK(pmap);
+		pte = pmap_pte_quick(pmap, pv->pv_va);
+		if ((*pte & PG_M) != 0) {
+			/*
+			 * Regardless of whether a pte is 32 or 64 bits
+			 * in size, PG_M is among the least significant
+			 * 32 bits. 
+			 */
+			atomic_clear_int((u_int *)pte, PG_M);
+			pmap_invalidate_page(pmap, pv->pv_va);
+		}
+		PMAP_UNLOCK(pmap);
+	}
+	sched_unpin();
 }
 
 /*
@@ -3197,7 +3207,30 @@ pmap_clear_modify(vm_page_t m)
 void
 pmap_clear_reference(vm_page_t m)
 {
-	pmap_clear_ptes(m, PG_A);
+	pv_entry_t pv;
+	pmap_t pmap;
+	pt_entry_t *pte;
+
+	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
+	if ((m->flags & PG_FICTITIOUS) != 0)
+		return;
+	sched_pin();
+	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
+		pmap = PV_PMAP(pv);
+		PMAP_LOCK(pmap);
+		pte = pmap_pte_quick(pmap, pv->pv_va);
+		if ((*pte & PG_A) != 0) {
+			/*
+			 * Regardless of whether a pte is 32 or 64 bits
+			 * in size, PG_A is among the least significant
+			 * 32 bits. 
+			 */
+			atomic_clear_int((u_int *)pte, PG_A);
+			pmap_invalidate_page(pmap, pv->pv_va);
+		}
+		PMAP_UNLOCK(pmap);
+	}
+	sched_unpin();
 }
 
 /*
-- 
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