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Date:      Sat, 20 Mar 2010 14:35:24 +0000 (UTC)
From:      Nathan Whitehorn <nwhitehorn@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r205370 - head/sys/powerpc/aim
Message-ID:  <201003201435.o2KEZOFj099799@svn.freebsd.org>
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Author: nwhitehorn
Date: Sat Mar 20 14:35:24 2010
New Revision: 205370
URL: http://svn.freebsd.org/changeset/base/205370

Log:
  Revisit locking in the 64-bit AIM PMAP. The PVO head for a page is
  generally protected by the VM page queue mutex. Instead of extending the
  table lock to cover the PVO heads, add some asserts that the page queue
  mutex is in fact held. This fixes several LORs and possible deadlocks.
  
  This also adds an optimization to moea64_kextract() useful for
  direct-mapped quantities, like UMA buffers. Being able to use this from
  inside UMA removes an additional LOR.

Modified:
  head/sys/powerpc/aim/mmu_oea64.c

Modified: head/sys/powerpc/aim/mmu_oea64.c
==============================================================================
--- head/sys/powerpc/aim/mmu_oea64.c	Sat Mar 20 14:26:30 2010	(r205369)
+++ head/sys/powerpc/aim/mmu_oea64.c	Sat Mar 20 14:35:24 2010	(r205370)
@@ -1507,10 +1507,10 @@ moea64_remove_write(mmu_t mmu, vm_page_t
 		return;
 	lo = moea64_attr_fetch(m);
 	SYNC();
-	LOCK_TABLE();
 	LIST_FOREACH(pvo, vm_page_to_pvoh(m), pvo_vlink) {
 		pmap = pvo->pvo_pmap;
 		PMAP_LOCK(pmap);
+		LOCK_TABLE();
 		if ((pvo->pvo_pte.lpte.pte_lo & LPTE_PP) != LPTE_BR) {
 			pt = moea64_pvo_to_pte(pvo, -1);
 			pvo->pvo_pte.lpte.pte_lo &= ~LPTE_PP;
@@ -1523,9 +1523,9 @@ moea64_remove_write(mmu_t mmu, vm_page_t
 				    pvo->pvo_pmap, PVO_VADDR(pvo));
 			}
 		}
+		UNLOCK_TABLE();
 		PMAP_UNLOCK(pmap);
 	}
-	UNLOCK_TABLE();
 	if ((lo & LPTE_CHG) != 0) {
 		moea64_attr_clear(m, LPTE_CHG);
 		vm_page_dirty(m);
@@ -1604,6 +1604,13 @@ moea64_kextract(mmu_t mmu, vm_offset_t v
 	struct		pvo_entry *pvo;
 	vm_paddr_t pa;
 
+	/*
+	 * Shortcut the direct-mapped case when applicable.  We never put
+	 * anything but 1:1 mappings below VM_MIN_KERNEL_ADDRESS.
+	 */
+	if (va < VM_MIN_KERNEL_ADDRESS)
+		return (va);
+
 	PMAP_LOCK(kernel_pmap);
 	pvo = moea64_pvo_find_va(kernel_pmap, va & ~ADDR_POFF, NULL);
 	KASSERT(pvo != NULL, ("moea64_kextract: no addr found"));
@@ -1661,17 +1668,15 @@ moea64_page_exists_quick(mmu_t mmu, pmap
         if (!moea64_initialized || (m->flags & PG_FICTITIOUS))
                 return FALSE;
 
+	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
+
 	loops = 0;
-	LOCK_TABLE();
 	LIST_FOREACH(pvo, vm_page_to_pvoh(m), pvo_vlink) {
-		if (pvo->pvo_pmap == pmap) {
-			UNLOCK_TABLE();
+		if (pvo->pvo_pmap == pmap) 
 			return (TRUE);
-		}
 		if (++loops >= 16)
 			break;
 	}
-	UNLOCK_TABLE();
 
 	return (FALSE);
 }
@@ -1690,11 +1695,9 @@ moea64_page_wired_mappings(mmu_t mmu, vm
 	if (!moea64_initialized || (m->flags & PG_FICTITIOUS) != 0)
 		return (count);
 	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
-	LOCK_TABLE();
 	LIST_FOREACH(pvo, vm_page_to_pvoh(m), pvo_vlink)
 		if ((pvo->pvo_vaddr & PVO_WIRED) != 0)
 			count++;
-	UNLOCK_TABLE();
 	return (count);
 }
 
@@ -1913,7 +1916,6 @@ moea64_remove_all(mmu_t mmu, vm_page_t m
 	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
 
 	pvo_head = vm_page_to_pvoh(m);
-	LOCK_TABLE();
 	for (pvo = LIST_FIRST(pvo_head); pvo != NULL; pvo = next_pvo) {
 		next_pvo = LIST_NEXT(pvo, pvo_vlink);
 
@@ -1923,7 +1925,6 @@ moea64_remove_all(mmu_t mmu, vm_page_t m
 		moea64_pvo_remove(pvo, -1);
 		PMAP_UNLOCK(pmap);
 	}
-	UNLOCK_TABLE();
 	if ((m->flags & PG_WRITEABLE) && moea64_is_modified(mmu, m)) {
 		moea64_attr_clear(m, LPTE_CHG);
 		vm_page_dirty(m);
@@ -2334,7 +2335,8 @@ moea64_query_bit(vm_page_t m, u_int64_t 
 	if (moea64_attr_fetch(m) & ptebit)
 		return (TRUE);
 
-	LOCK_TABLE();
+	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
+
 	LIST_FOREACH(pvo, vm_page_to_pvoh(m), pvo_vlink) {
 		MOEA_PVO_CHECK(pvo);	/* sanity check */
 
@@ -2344,7 +2346,6 @@ moea64_query_bit(vm_page_t m, u_int64_t 
 		 */
 		if (pvo->pvo_pte.lpte.pte_lo & ptebit) {
 			moea64_attr_save(m, ptebit);
-			UNLOCK_TABLE();
 			MOEA_PVO_CHECK(pvo);	/* sanity check */
 			return (TRUE);
 		}
@@ -2364,6 +2365,7 @@ moea64_query_bit(vm_page_t m, u_int64_t 
 		 * REF/CHG bits from the valid PTE.  If the appropriate
 		 * ptebit is set, cache it and return success.
 		 */
+		LOCK_TABLE();
 		pt = moea64_pvo_to_pte(pvo, -1);
 		if (pt != NULL) {
 			moea64_pte_synch(pt, &pvo->pvo_pte.lpte);
@@ -2375,8 +2377,8 @@ moea64_query_bit(vm_page_t m, u_int64_t 
 				return (TRUE);
 			}
 		}
+		UNLOCK_TABLE();
 	}
-	UNLOCK_TABLE();
 
 	return (FALSE);
 }
@@ -2389,6 +2391,8 @@ moea64_clear_bit(vm_page_t m, u_int64_t 
 	struct	lpte *pt;
 	uint64_t rv;
 
+	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
+
 	/*
 	 * Clear the cached value.
 	 */
@@ -2409,10 +2413,10 @@ moea64_clear_bit(vm_page_t m, u_int64_t 
 	 * valid pte clear the ptebit from the valid pte.
 	 */
 	count = 0;
-	LOCK_TABLE();
 	LIST_FOREACH(pvo, vm_page_to_pvoh(m), pvo_vlink) {
 		MOEA_PVO_CHECK(pvo);	/* sanity check */
 
+		LOCK_TABLE();
 		pt = moea64_pvo_to_pte(pvo, -1);
 		if (pt != NULL) {
 			moea64_pte_synch(pt, &pvo->pvo_pte.lpte);
@@ -2424,8 +2428,8 @@ moea64_clear_bit(vm_page_t m, u_int64_t 
 		rv |= pvo->pvo_pte.lpte.pte_lo;
 		pvo->pvo_pte.lpte.pte_lo &= ~ptebit;
 		MOEA_PVO_CHECK(pvo);	/* sanity check */
+		UNLOCK_TABLE();
 	}
-	UNLOCK_TABLE();
 
 	if (origbit != NULL) {
 		*origbit = rv;

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