Rename pmap_changebit() to pmap_clear_ptes() and remove the last

parameter.  The new name better reflects what the function does and
how it is used.  The last parameter was always FALSE.

Note: In theory, gcc would perform constant propagation and dead code
elimination to achieve the same effect as removing the last parameter,
which is always FALSE.  In practice, recent versions do not.  So, there
is little point in letting unused code pessimize execution.

2 files changed, 38 insertions, 50 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 915e647..c34607d 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -208,7 +208,7 @@ static caddr_t crashdumpmap;
 static PMAP_INLINE void	free_pv_entry(pv_entry_t pv);
 static pv_entry_t get_pv_entry(void);
 static void	amd64_protection_init(void);
-static void	pmap_changebit(vm_page_t m, int bit, boolean_t setem)
+static void	pmap_clear_ptes(vm_page_t m, int bit)
     __always_inline;
 
 static int pmap_remove_pte(pmap_t pmap, pt_entry_t *ptq, vm_offset_t sva);
@@ -2611,17 +2611,17 @@ pmap_is_modified(vm_page_t m)
 }
 
 /*
- * this routine is used to modify bits in ptes
+ *	Clear the given bit in each of the given page's ptes.
  */
 static __inline void
-pmap_changebit(vm_page_t m, int bit, boolean_t setem)
+pmap_clear_ptes(vm_page_t m, int bit)
 {
 	register pv_entry_t pv;
-	register pt_entry_t *pte;
+	pt_entry_t pbits, *pte;
 	int s;
 
 	if (!pmap_initialized || (m->flags & PG_FICTITIOUS) ||
-	    (!setem && bit == PG_RW && (m->flags & PG_WRITEABLE) == 0))
+	    (bit == PG_RW && (m->flags & PG_WRITEABLE) == 0))
 		return;
 
 	s = splvm();
@@ -2634,7 +2634,7 @@ pmap_changebit(vm_page_t m, int bit, boolean_t setem)
 		/*
 		 * don't write protect pager mappings
 		 */
-		if (!setem && (bit == PG_RW)) {
+		if (bit == PG_RW) {
 			if (!pmap_track_modified(pv->pv_va))
 				continue;
 		}
@@ -2647,26 +2647,20 @@ pmap_changebit(vm_page_t m, int bit, boolean_t setem)
 #endif
 
 		pte = pmap_pte(pv->pv_pmap, pv->pv_va);
-
-		if (setem) {
-			*pte |= bit;
-			pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
-		} else {
-			pt_entry_t pbits = *pte;
-			if (pbits & bit) {
-				if (bit == PG_RW) {
-					if (pbits & PG_M) {
-						vm_page_dirty(m);
-					}
-					pte_store(pte, pbits & ~(PG_M|PG_RW));
-				} else {
-					pte_store(pte, pbits & ~bit);
+		pbits = *pte;
+		if (pbits & bit) {
+			if (bit == PG_RW) {
+				if (pbits & PG_M) {
+					vm_page_dirty(m);
 				}
-				pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
+				pte_store(pte, pbits & ~(PG_M|PG_RW));
+			} else {
+				pte_store(pte, pbits & ~bit);
 			}
+			pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
 		}
 	}
-	if (!setem && bit == PG_RW)
+	if (bit == PG_RW)
 		vm_page_flag_clear(m, PG_WRITEABLE);
 	splx(s);
 }
@@ -2681,7 +2675,7 @@ 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_changebit(m, PG_RW, FALSE);
+			pmap_clear_ptes(m, PG_RW);
 		} else {
 			pmap_remove_all(m);
 		}
@@ -2752,7 +2746,7 @@ pmap_ts_referenced(vm_page_t m)
 void
 pmap_clear_modify(vm_page_t m)
 {
-	pmap_changebit(m, PG_M, FALSE);
+	pmap_clear_ptes(m, PG_M);
 }
 
 /*
@@ -2763,7 +2757,7 @@ pmap_clear_modify(vm_page_t m)
 void
 pmap_clear_reference(vm_page_t m)
 {
-	pmap_changebit(m, PG_A, FALSE);
+	pmap_clear_ptes(m, PG_A);
 }
 
 /*
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c
index 3e2adf9..174b30c 100644
--- a/sys/i386/i386/pmap.c
+++ b/sys/i386/i386/pmap.c
@@ -240,7 +240,7 @@ static pt_entry_t *PADDR1 = 0;
 static PMAP_INLINE void	free_pv_entry(pv_entry_t pv);
 static pv_entry_t get_pv_entry(void);
 static void	i386_protection_init(void);
-static void	pmap_changebit(vm_page_t m, int bit, boolean_t setem)
+static void	pmap_clear_ptes(vm_page_t m, int bit)
     __always_inline;
 
 static int pmap_remove_pte(pmap_t pmap, pt_entry_t *ptq, vm_offset_t sva);
@@ -2839,17 +2839,17 @@ pmap_is_modified(vm_page_t m)
 }
 
 /*
- * this routine is used to modify bits in ptes
+ *	Clear the given bit in each of the given page's ptes.
  */
 static __inline void
-pmap_changebit(vm_page_t m, int bit, boolean_t setem)
+pmap_clear_ptes(vm_page_t m, int bit)
 {
 	register pv_entry_t pv;
-	register pt_entry_t *pte;
+	pt_entry_t pbits, *pte;
 	int s;
 
 	if (!pmap_initialized || (m->flags & PG_FICTITIOUS) ||
-	    (!setem && bit == PG_RW && (m->flags & PG_WRITEABLE) == 0))
+	    (bit == PG_RW && (m->flags & PG_WRITEABLE) == 0))
 		return;
 
 	s = splvm();
@@ -2862,7 +2862,7 @@ pmap_changebit(vm_page_t m, int bit, boolean_t setem)
 		/*
 		 * don't write protect pager mappings
 		 */
-		if (!setem && (bit == PG_RW)) {
+		if (bit == PG_RW) {
 			if (!pmap_track_modified(pv->pv_va))
 				continue;
 		}
@@ -2875,26 +2875,20 @@ pmap_changebit(vm_page_t m, int bit, boolean_t setem)
 #endif
 
 		pte = pmap_pte_quick(pv->pv_pmap, pv->pv_va);
-
-		if (setem) {
-			*pte |= bit;
-			pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
-		} else {
-			pt_entry_t pbits = *pte;
-			if (pbits & bit) {
-				if (bit == PG_RW) {
-					if (pbits & PG_M) {
-						vm_page_dirty(m);
-					}
-					pte_store(pte, pbits & ~(PG_M|PG_RW));
-				} else {
-					pte_store(pte, pbits & ~bit);
+		pbits = *pte;
+		if (pbits & bit) {
+			if (bit == PG_RW) {
+				if (pbits & PG_M) {
+					vm_page_dirty(m);
 				}
-				pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
+				pte_store(pte, pbits & ~(PG_M|PG_RW));
+			} else {
+				pte_store(pte, pbits & ~bit);
 			}
+			pmap_invalidate_page(pv->pv_pmap, pv->pv_va);
 		}
 	}
-	if (!setem && bit == PG_RW)
+	if (bit == PG_RW)
 		vm_page_flag_clear(m, PG_WRITEABLE);
 	splx(s);
 }
@@ -2909,7 +2903,7 @@ 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_changebit(m, PG_RW, FALSE);
+			pmap_clear_ptes(m, PG_RW);
 		} else {
 			pmap_remove_all(m);
 		}
@@ -2980,7 +2974,7 @@ pmap_ts_referenced(vm_page_t m)
 void
 pmap_clear_modify(vm_page_t m)
 {
-	pmap_changebit(m, PG_M, FALSE);
+	pmap_clear_ptes(m, PG_M);
 }
 
 /*
@@ -2991,7 +2985,7 @@ pmap_clear_modify(vm_page_t m)
 void
 pmap_clear_reference(vm_page_t m)
 {
-	pmap_changebit(m, PG_A, FALSE);
+	pmap_clear_ptes(m, PG_A);
 }
 
 /*