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Date:      Sat, 13 Oct 2012 22:22:54 +0000 (UTC)
From:      Alan Cox <alc@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org
Subject:   svn commit: r241518 - in stable/9/sys/i386: i386 xen
Message-ID:  <201210132222.q9DMMsql020624@svn.freebsd.org>
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Author: alc
Date: Sat Oct 13 22:22:53 2012
New Revision: 241518
URL: http://svn.freebsd.org/changeset/base/241518

Log:
  MFC r241353, r241356, r241400
    To avoid page table page corruption, change pmap_pv_reclaim()'s method
    of mapping page table pages.
  
    Add some assertions that were helpful in debugging the page table page
    corruption.

Modified:
  stable/9/sys/i386/i386/pmap.c
  stable/9/sys/i386/xen/pmap.c
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/i386/i386/pmap.c
==============================================================================
--- stable/9/sys/i386/i386/pmap.c	Sat Oct 13 20:19:43 2012	(r241517)
+++ stable/9/sys/i386/i386/pmap.c	Sat Oct 13 22:22:53 2012	(r241518)
@@ -482,7 +482,8 @@ pmap_bootstrap(vm_paddr_t firstaddr)
 	KPTmap -= i386_btop(KPTDI << PDRSHIFT);
 
 	/*
-	 * ptemap is used for pmap_pte_quick
+	 * PADDR1 and PADDR2 are used by pmap_pte_quick() and pmap_pte(),
+	 * respectively.
 	 */
 	SYSMAP(pt_entry_t *, PMAP1, PADDR1, 1)
 	SYSMAP(pt_entry_t *, PMAP2, PADDR2, 1)
@@ -2235,7 +2236,6 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 	pmap = NULL;
 	free = m_pc = NULL;
 	TAILQ_INIT(&newtail);
-	sched_pin();
 	while ((pc = TAILQ_FIRST(&pv_chunks)) != NULL && (pv_vafree == 0 ||
 	    free == NULL)) {
 		TAILQ_REMOVE(&pv_chunks, pc, pc_lru);
@@ -2269,10 +2269,16 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 				pde = pmap_pde(pmap, va);
 				if ((*pde & PG_PS) != 0)
 					continue;
-				pte = pmap_pte_quick(pmap, va);
-				if ((*pte & PG_W) != 0)
+				pte = pmap_pte(pmap, va);
+				tpte = *pte;
+				if ((tpte & PG_W) == 0)
+					tpte = pte_load_clear(pte);
+				pmap_pte_release(pte);
+				if ((tpte & PG_W) != 0)
 					continue;
-				tpte = pte_load_clear(pte);
+				KASSERT(tpte != 0,
+				    ("pmap_pv_reclaim: pmap %p va %x zero pte",
+				    pmap, va));
 				if ((tpte & PG_G) != 0)
 					pmap_invalidate_page(pmap, va);
 				m = PHYS_TO_VM_PAGE(tpte & PG_FRAME);
@@ -2330,7 +2336,6 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 		}
 	}
 out:
-	sched_unpin();
 	TAILQ_CONCAT(&pv_chunks, &newtail, pc_lru);
 	if (pmap != NULL) {
 		pmap_invalidate_all(pmap);
@@ -2870,6 +2875,8 @@ pmap_remove_pte(pmap_t pmap, pt_entry_t 
 	rw_assert(&pvh_global_lock, RA_WLOCKED);
 	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
 	oldpte = pte_load_clear(ptq);
+	KASSERT(oldpte != 0,
+	    ("pmap_remove_pte: pmap %p va %x zero pte", pmap, va));
 	if (oldpte & PG_W)
 		pmap->pm_stats.wired_count -= 1;
 	/*
@@ -3074,6 +3081,8 @@ small_mappings:
 		    " a 4mpage in page %p's pv list", m));
 		pte = pmap_pte_quick(pmap, pv->pv_va);
 		tpte = pte_load_clear(pte);
+		KASSERT(tpte != 0, ("pmap_remove_all: pmap %p va %x zero pte",
+		    pmap, pv->pv_va));
 		if (tpte & PG_W)
 			pmap->pm_stats.wired_count--;
 		if (tpte & PG_A)
@@ -4373,6 +4382,8 @@ pmap_remove_pages(pmap_t pmap)
 	PMAP_LOCK(pmap);
 	sched_pin();
 	TAILQ_FOREACH_SAFE(pc, &pmap->pm_pvchunk, pc_list, npc) {
+		KASSERT(pc->pc_pmap == pmap, ("Wrong pmap %p %p", pmap,
+		    pc->pc_pmap));
 		allfree = 1;
 		for (field = 0; field < _NPCM; field++) {
 			inuse = ~pc->pc_map[field] & pc_freemask[field];

Modified: stable/9/sys/i386/xen/pmap.c
==============================================================================
--- stable/9/sys/i386/xen/pmap.c	Sat Oct 13 20:19:43 2012	(r241517)
+++ stable/9/sys/i386/xen/pmap.c	Sat Oct 13 22:22:53 2012	(r241518)
@@ -437,7 +437,8 @@ pmap_bootstrap(vm_paddr_t firstaddr)
 	SYSMAP(struct msgbuf *, unused, msgbufp, atop(round_page(msgbufsize)))
 
 	/*
-	 * ptemap is used for pmap_pte_quick
+	 * PADDR1 and PADDR2 are used by pmap_pte_quick() and pmap_pte(),
+	 * respectively.
 	 */
 	SYSMAP(pt_entry_t *, PMAP1, PADDR1, 1)
 	SYSMAP(pt_entry_t *, PMAP2, PADDR2, 1)
@@ -1986,7 +1987,6 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 	pmap = NULL;
 	free = m_pc = NULL;
 	TAILQ_INIT(&newtail);
-	sched_pin();
 	while ((pc = TAILQ_FIRST(&pv_chunks)) != NULL && (pv_vafree == 0 ||
 	    free == NULL)) {
 		TAILQ_REMOVE(&pv_chunks, pc, pc_lru);
@@ -2017,10 +2017,16 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 				bit = bsfl(inuse);
 				pv = &pc->pc_pventry[field * 32 + bit];
 				va = pv->pv_va;
-				pte = pmap_pte_quick(pmap, va);
-				if ((*pte & PG_W) != 0)
+				pte = pmap_pte(pmap, va);
+				tpte = *pte;
+				if ((tpte & PG_W) == 0)
+					tpte = pte_load_clear(pte);
+				pmap_pte_release(pte);
+				if ((tpte & PG_W) != 0)
 					continue;
-				tpte = pte_load_clear(pte);
+				KASSERT(tpte != 0,
+				    ("pmap_pv_reclaim: pmap %p va %x zero pte",
+				    pmap, va));
 				if ((tpte & PG_G) != 0)
 					pmap_invalidate_page(pmap, va);
 				m = PHYS_TO_VM_PAGE(tpte & PG_FRAME);
@@ -2072,7 +2078,6 @@ pmap_pv_reclaim(pmap_t locked_pmap)
 		}
 	}
 out:
-	sched_unpin();
 	TAILQ_CONCAT(&pv_chunks, &newtail, pc_lru);
 	if (pmap != NULL) {
 		pmap_invalidate_all(pmap);
@@ -2294,6 +2299,8 @@ pmap_remove_pte(pmap_t pmap, pt_entry_t 
 	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
 	oldpte = *ptq;
 	PT_SET_VA_MA(ptq, 0, TRUE);
+	KASSERT(oldpte != 0,
+	    ("pmap_remove_pte: pmap %p va %x zero pte", pmap, va));
 	if (oldpte & PG_W)
 		pmap->pm_stats.wired_count -= 1;
 	/*
@@ -2478,6 +2485,8 @@ pmap_remove_all(vm_page_t m)
 		pte = pmap_pte_quick(pmap, pv->pv_va);
 		tpte = *pte;
 		PT_SET_VA_MA(pte, 0, TRUE);
+		KASSERT(tpte != 0, ("pmap_remove_all: pmap %p va %x zero pte",
+		    pmap, pv->pv_va));
 		if (tpte & PG_W)
 			pmap->pm_stats.wired_count--;
 		if (tpte & PG_A)
@@ -3541,6 +3550,8 @@ pmap_remove_pages(pmap_t pmap)
 	PMAP_LOCK(pmap);
 	sched_pin();
 	TAILQ_FOREACH_SAFE(pc, &pmap->pm_pvchunk, pc_list, npc) {
+		KASSERT(pc->pc_pmap == pmap, ("Wrong pmap %p %p", pmap,
+		    pc->pc_pmap));
 		allfree = 1;
 		for (field = 0; field < _NPCM; field++) {
 			inuse = ~pc->pc_map[field] & pc_freemask[field];

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