svn commit: r216333 - head/sys/i386/i386

[Alan Cox]

Author: alc
Date: Thu Dec  9 20:16:00 2010
New Revision: 216333
URL: http://svn.freebsd.org/changeset/base/216333

Log:
  When r207410 eliminated the acquisition and release of the page queues
  lock from pmap_extract_and_hold(), it didn't take into account that
  pmap_pte_quick() sometimes requires the page queues lock to be held.
  This change reimplements pmap_extract_and_hold() such that it no
  longer uses pmap_pte_quick(), and thus never requires the page queues
  lock.
  
  For consistency, adopt the same idiom as used by the new
  implementation of pmap_extract_and_hold() in pmap_extract() and
  pmap_mincore().  It also happens to make these functions shorter.
  
  Fix a style error in pmap_pte().
  
  Reviewed by:	kib@

Modified:
  head/sys/i386/i386/pmap.c

Modified: head/sys/i386/i386/pmap.c
==============================================================================
--- head/sys/i386/i386/pmap.c	Thu Dec  9 20:05:29 2010	(r216332)
+++ head/sys/i386/i386/pmap.c	Thu Dec  9 20:16:00 2010	(r216333)
@@ -1213,7 +1213,7 @@ pmap_pte(pmap_t pmap, vm_offset_t va)
 		}
 		return (PADDR2 + (i386_btop(va) & (NPTEPG - 1)));
 	}
-	return (0);
+	return (NULL);
 }
 
 /*
@@ -1291,21 +1291,19 @@ pmap_pte_quick(pmap_t pmap, vm_offset_t 
 vm_paddr_t 
 pmap_extract(pmap_t pmap, vm_offset_t va)
 {
+	pt_entry_t pte, *ptep;
 	vm_paddr_t rtval;
-	pt_entry_t *pte;
-	pd_entry_t pde;
 
 	rtval = 0;
 	PMAP_LOCK(pmap);
-	pde = pmap->pm_pdir[va >> PDRSHIFT];
-	if (pde != 0) {
-		if ((pde & PG_PS) != 0)
-			rtval = (pde & PG_PS_FRAME) | (va & PDRMASK);
-		else {
-			pte = pmap_pte(pmap, va);
-			rtval = (*pte & PG_FRAME) | (va & PAGE_MASK);
-			pmap_pte_release(pte);
-		}
+	ptep = pmap_pte(pmap, va);
+	pte = (ptep != NULL) ? *ptep : 0;
+	pmap_pte_release(ptep);
+	if ((pte & PG_V) != 0) {
+		if ((pte & PG_PS) != 0)
+			rtval = (pte & PG_PS_FRAME) | (va & PDRMASK);
+		else
+			rtval = (pte & PG_FRAME) | (va & PAGE_MASK);
 	}
 	PMAP_UNLOCK(pmap);
 	return (rtval);
@@ -1321,40 +1319,30 @@ pmap_extract(pmap_t pmap, vm_offset_t va
 vm_page_t
 pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
 {
-	pd_entry_t pde;
-	pt_entry_t pte;
+	pt_entry_t pte, *ptep;
+	vm_paddr_t locked_pa, pa;
 	vm_page_t m;
-	vm_paddr_t pa;
 
-	pa = 0;
+	locked_pa = 0;
 	m = NULL;
 	PMAP_LOCK(pmap);
 retry:
-	pde = *pmap_pde(pmap, va);
-	if (pde != 0) {
-		if (pde & PG_PS) {
-			if ((pde & PG_RW) || (prot & VM_PROT_WRITE) == 0) {
-				if (vm_page_pa_tryrelock(pmap, (pde & PG_PS_FRAME) |
-				       (va & PDRMASK), &pa))
-					goto retry;
-				m = PHYS_TO_VM_PAGE((pde & PG_PS_FRAME) |
-				    (va & PDRMASK));
-				vm_page_hold(m);
-			}
-		} else {
-			sched_pin();
-			pte = *pmap_pte_quick(pmap, va);
-			if (pte != 0 &&
-			    ((pte & PG_RW) || (prot & VM_PROT_WRITE) == 0)) {
-				if (vm_page_pa_tryrelock(pmap, pte & PG_FRAME, &pa))
-					goto retry;
-				m = PHYS_TO_VM_PAGE(pte & PG_FRAME);
-				vm_page_hold(m);
-			}
-			sched_unpin();
-		}
+	ptep = pmap_pte(pmap, va);
+	pte = (ptep != NULL) ? *ptep : 0;
+	pmap_pte_release(ptep);
+	if ((pte & PG_V) != 0 &&
+	    ((pte & PG_RW) != 0 || (prot & VM_PROT_WRITE) == 0)) {
+		if ((pte & PG_PS) != 0) {
+			/* Compute the physical address of the 4KB page. */
+			pa = (pte & PG_PS_FRAME) | (va & PG_FRAME & PDRMASK);
+		} else
+			pa = pte & PG_FRAME;
+		if (vm_page_pa_tryrelock(pmap, pa, &locked_pa))
+			goto retry;
+		m = PHYS_TO_VM_PAGE(pa);
+		vm_page_hold(m);
+		PA_UNLOCK(locked_pa);
 	}
-	PA_UNLOCK_COND(pa);
 	PMAP_UNLOCK(pmap);
 	return (m);
 }
@@ -4991,39 +4979,30 @@ pmap_change_attr(vm_offset_t va, vm_size
 int
 pmap_mincore(pmap_t pmap, vm_offset_t addr, vm_paddr_t *locked_pa)
 {
-	pd_entry_t *pdep;
 	pt_entry_t *ptep, pte;
 	vm_paddr_t pa;
 	int val;
 
 	PMAP_LOCK(pmap);
 retry:
-	pdep = pmap_pde(pmap, addr);
-	if (*pdep != 0) {
-		if (*pdep & PG_PS) {
-			pte = *pdep;
+	ptep = pmap_pte(pmap, addr);
+	pte = (ptep != NULL) ? *ptep : 0;
+	pmap_pte_release(ptep);
+	if ((pte & PG_V) != 0) {
+		val = MINCORE_INCORE;
+		if ((pte & PG_PS) != 0) {
+			val |= MINCORE_SUPER;
 			/* Compute the physical address of the 4KB page. */
-			pa = ((*pdep & PG_PS_FRAME) | (addr & PDRMASK)) &
-			    PG_FRAME;
-			val = MINCORE_SUPER;
-		} else {
-			ptep = pmap_pte(pmap, addr);
-			pte = *ptep;
-			pmap_pte_release(ptep);
+			pa = (pte & PG_PS_FRAME) | (addr & PG_FRAME & PDRMASK);
+		} else
 			pa = pte & PG_FRAME;
-			val = 0;
-		}
-	} else {
-		pte = 0;
-		pa = 0;
-		val = 0;
-	}
-	if ((pte & PG_V) != 0) {
-		val |= MINCORE_INCORE;
 		if ((pte & (PG_M | PG_RW)) == (PG_M | PG_RW))
 			val |= MINCORE_MODIFIED | MINCORE_MODIFIED_OTHER;
 		if ((pte & PG_A) != 0)
 			val |= MINCORE_REFERENCED | MINCORE_REFERENCED_OTHER;
+	} else {
+		val = 0;
+		pa = 0;
 	}
 	if ((val & (MINCORE_MODIFIED_OTHER | MINCORE_REFERENCED_OTHER)) !=
 	    (MINCORE_MODIFIED_OTHER | MINCORE_REFERENCED_OTHER) &&