xref: /freebsd-9.3-release/sys/i386/i386/pmap.c

/*-
 * Copyright (c) 1991 Regents of the University of California.
 * All rights reserved.
 * Copyright (c) 1994 John S. Dyson
 * All rights reserved.
 * Copyright (c) 1994 David Greenman
 * All rights reserved.
 * Copyright (c) 2005-2008 Alan L. Cox <alc@cs.rice.edu>
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department and William Jolitz of UUNET Technologies Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	from:	@(#)pmap.c	7.7 (Berkeley)	5/12/91
 */
/*-
 * Copyright (c) 2003 Networks Associates Technology, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by Jake Burkholder,
 * Safeport Network Services, and Network Associates Laboratories, the
 * Security Research Division of Network Associates, Inc. under
 * DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA
 * CHATS research program.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: head/sys/i386/i386/pmap.c 194209 2009-06-14 19:51:43Z alc $");

/*
 *	Manages physical address maps.
 *
 *	In addition to hardware address maps, this
 *	module is called upon to provide software-use-only
 *	maps which may or may not be stored in the same
 *	form as hardware maps.  These pseudo-maps are
 *	used to store intermediate results from copy
 *	operations to and from address spaces.
 *
 *	Since the information managed by this module is
 *	also stored by the logical address mapping module,
 *	this module may throw away valid virtual-to-physical
 *	mappings at almost any time.  However, invalidations
 *	of virtual-to-physical mappings must be done as
 *	requested.
 *
 *	In order to cope with hardware architectures which
 *	make virtual-to-physical map invalidates expensive,
 *	this module may delay invalidate or reduced protection
 *	operations until such time as they are actually
 *	necessary.  This module is given full information as
 *	to which processors are currently using which maps,
 *	and to when physical maps must be made correct.
 */

#include "opt_cpu.h"
#include "opt_pmap.h"
#include "opt_msgbuf.h"
#include "opt_smp.h"
#include "opt_xbox.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mman.h>
#include <sys/msgbuf.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sx.h>
#include <sys/vmmeter.h>
#include <sys/sched.h>
#include <sys/sysctl.h>
#ifdef SMP
#include <sys/smp.h>
#endif

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_extern.h>
#include <vm/vm_pageout.h>
#include <vm/vm_pager.h>
#include <vm/vm_reserv.h>
#include <vm/uma.h>

#include <machine/cpu.h>
#include <machine/cputypes.h>
#include <machine/md_var.h>
#include <machine/pcb.h>
#include <machine/specialreg.h>
#ifdef SMP
#include <machine/smp.h>
#endif

#ifdef XBOX
#include <machine/xbox.h>
#endif

#if !defined(CPU_DISABLE_SSE) && defined(I686_CPU)
#define CPU_ENABLE_SSE
#endif

#ifndef PMAP_SHPGPERPROC
#define PMAP_SHPGPERPROC 200
#endif

#if !defined(DIAGNOSTIC)
#define PMAP_INLINE	__gnu89_inline
#else
#define PMAP_INLINE
#endif

#define PV_STATS
#ifdef PV_STATS
#define PV_STAT(x)	do { x ; } while (0)
#else
#define PV_STAT(x)	do { } while (0)
#endif

#define	pa_index(pa)	((pa) >> PDRSHIFT)
#define	pa_to_pvh(pa)	(&pv_table[pa_index(pa)])

/*
 * Get PDEs and PTEs for user/kernel address space
 */
#define	pmap_pde(m, v)	(&((m)->pm_pdir[(vm_offset_t)(v) >> PDRSHIFT]))
#define pdir_pde(m, v) (m[(vm_offset_t)(v) >> PDRSHIFT])

#define pmap_pde_v(pte)		((*(int *)pte & PG_V) != 0)
#define pmap_pte_w(pte)		((*(int *)pte & PG_W) != 0)
#define pmap_pte_m(pte)		((*(int *)pte & PG_M) != 0)
#define pmap_pte_u(pte)		((*(int *)pte & PG_A) != 0)
#define pmap_pte_v(pte)		((*(int *)pte & PG_V) != 0)

#define pmap_pte_set_w(pte, v)	((v) ? atomic_set_int((u_int *)(pte), PG_W) : \
    atomic_clear_int((u_int *)(pte), PG_W))
#define pmap_pte_set_prot(pte, v) ((*(int *)pte &= ~PG_PROT), (*(int *)pte |= (v)))

struct pmap kernel_pmap_store;
LIST_HEAD(pmaplist, pmap);
static struct pmaplist allpmaps;
static struct mtx allpmaps_lock;

vm_offset_t virtual_avail;	/* VA of first avail page (after kernel bss) */
vm_offset_t virtual_end;	/* VA of last avail page (end of kernel AS) */
int pgeflag = 0;		/* PG_G or-in */
int pseflag = 0;		/* PG_PS or-in */

static int nkpt;
vm_offset_t kernel_vm_end;
extern u_int32_t KERNend;

#ifdef PAE
pt_entry_t pg_nx;
static uma_zone_t pdptzone;
#endif

static int pat_works;			/* Is page attribute table sane? */

SYSCTL_NODE(_vm, OID_AUTO, pmap, CTLFLAG_RD, 0, "VM/pmap parameters");

static int pg_ps_enabled;
SYSCTL_INT(_vm_pmap, OID_AUTO, pg_ps_enabled, CTLFLAG_RD, &pg_ps_enabled, 0,
    "Are large page mappings enabled?");

/*
 * Data for the pv entry allocation mechanism
 */
static int pv_entry_count = 0, pv_entry_max = 0, pv_entry_high_water = 0;
static struct md_page *pv_table;
static int shpgperproc = PMAP_SHPGPERPROC;

struct pv_chunk *pv_chunkbase;		/* KVA block for pv_chunks */
int pv_maxchunks;			/* How many chunks we have KVA for */
vm_offset_t pv_vafree;			/* freelist stored in the PTE */

/*
 * All those kernel PT submaps that BSD is so fond of
 */
struct sysmaps {
	struct	mtx lock;
	pt_entry_t *CMAP1;
	pt_entry_t *CMAP2;
	caddr_t	CADDR1;
	caddr_t	CADDR2;
};
static struct sysmaps sysmaps_pcpu[MAXCPU];
pt_entry_t *CMAP1 = 0;
static pt_entry_t *CMAP3;
caddr_t CADDR1 = 0, ptvmmap = 0;
static caddr_t CADDR3;
struct msgbuf *msgbufp = 0;

/*
 * Crashdump maps.
 */
static caddr_t crashdumpmap;

static pt_entry_t *PMAP1 = 0, *PMAP2;
static pt_entry_t *PADDR1 = 0, *PADDR2;
#ifdef SMP
static int PMAP1cpu;
static int PMAP1changedcpu;
SYSCTL_INT(_debug, OID_AUTO, PMAP1changedcpu, CTLFLAG_RD,
	   &PMAP1changedcpu, 0,
	   "Number of times pmap_pte_quick changed CPU with same PMAP1");
#endif
static int PMAP1changed;
SYSCTL_INT(_debug, OID_AUTO, PMAP1changed, CTLFLAG_RD,
	   &PMAP1changed, 0,
	   "Number of times pmap_pte_quick changed PMAP1");
static int PMAP1unchanged;
SYSCTL_INT(_debug, OID_AUTO, PMAP1unchanged, CTLFLAG_RD,
	   &PMAP1unchanged, 0,
	   "Number of times pmap_pte_quick didn't change PMAP1");
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_pv_demote_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa);
static boolean_t pmap_pv_insert_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa);
static void	pmap_pv_promote_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa);
static void	pmap_pvh_free(struct md_page *pvh, pmap_t pmap, vm_offset_t va);
static pv_entry_t pmap_pvh_remove(struct md_page *pvh, pmap_t pmap,
		    vm_offset_t va);
static int	pmap_pvh_wired_mappings(struct md_page *pvh, int count);

static boolean_t pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va);
static boolean_t pmap_enter_pde(pmap_t pmap, vm_offset_t va, vm_page_t m,
    vm_prot_t prot);
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);
static void pmap_insert_pt_page(pmap_t pmap, vm_page_t mpte);
static boolean_t pmap_is_modified_pvh(struct md_page *pvh);
static void pmap_kenter_attr(vm_offset_t va, vm_paddr_t pa, int mode);
static vm_page_t pmap_lookup_pt_page(pmap_t pmap, vm_offset_t va);
static void pmap_promote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va);
static boolean_t pmap_protect_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t sva,
    vm_prot_t prot);
static void pmap_remove_pde(pmap_t pmap, pd_entry_t *pdq, vm_offset_t sva,
    vm_page_t *free);
static int pmap_remove_pte(pmap_t pmap, pt_entry_t *ptq, vm_offset_t sva,
    vm_page_t *free);
static void pmap_remove_pt_page(pmap_t pmap, vm_page_t mpte);
static void pmap_remove_page(struct pmap *pmap, vm_offset_t va,
    vm_page_t *free);
static void pmap_remove_entry(struct pmap *pmap, vm_page_t m,
					vm_offset_t va);
static void pmap_insert_entry(pmap_t pmap, vm_offset_t va, vm_page_t m);
static boolean_t pmap_try_insert_pv_entry(pmap_t pmap, vm_offset_t va,
    vm_page_t m);

static vm_page_t pmap_allocpte(pmap_t pmap, vm_offset_t va, int flags);

static vm_page_t _pmap_allocpte(pmap_t pmap, unsigned ptepindex, int flags);
static int _pmap_unwire_pte_hold(pmap_t pmap, vm_page_t m, vm_page_t *free);
static pt_entry_t *pmap_pte_quick(pmap_t pmap, vm_offset_t va);
static void pmap_pte_release(pt_entry_t *pte);
static int pmap_unuse_pt(pmap_t, vm_offset_t, vm_page_t *);
static vm_offset_t pmap_kmem_choose(vm_offset_t addr);
#ifdef PAE
static void *pmap_pdpt_allocf(uma_zone_t zone, int bytes, u_int8_t *flags, int wait);
#endif

CTASSERT(1 << PDESHIFT == sizeof(pd_entry_t));
CTASSERT(1 << PTESHIFT == sizeof(pt_entry_t));

/*
 * If you get an error here, then you set KVA_PAGES wrong! See the
 * description of KVA_PAGES in sys/i386/include/pmap.h. It must be
 * multiple of 4 for a normal kernel, or a multiple of 8 for a PAE.
 */
CTASSERT(KERNBASE % (1 << 24) == 0);

/*
 * Move the kernel virtual free pointer to the next
 * 4MB.  This is used to help improve performance
 * by using a large (4MB) page for much of the kernel
 * (.text, .data, .bss)
 */
static vm_offset_t
pmap_kmem_choose(vm_offset_t addr)
{
	vm_offset_t newaddr = addr;

#ifndef DISABLE_PSE
	if (cpu_feature & CPUID_PSE)
		newaddr = (addr + PDRMASK) & ~PDRMASK;
#endif
	return newaddr;
}

/*
 *	Bootstrap the system enough to run with virtual memory.
 *
 *	On the i386 this is called after mapping has already been enabled
 *	and just syncs the pmap module with what has already been done.
 *	[We can't call it easily with mapping off since the kernel is not
 *	mapped with PA == VA, hence we would have to relocate every address
 *	from the linked base (virtual) address "KERNBASE" to the actual
 *	(physical) address starting relative to 0]
 */
void
pmap_bootstrap(vm_paddr_t firstaddr)
{
	vm_offset_t va;
	pt_entry_t *pte, *unused;
	struct sysmaps *sysmaps;
	int i;

	/*
	 * XXX The calculation of virtual_avail is wrong. It's NKPT*PAGE_SIZE too
	 * large. It should instead be correctly calculated in locore.s and
	 * not based on 'first' (which is a physical address, not a virtual
	 * address, for the start of unused physical memory). The kernel
	 * page tables are NOT double mapped and thus should not be included
	 * in this calculation.
	 */
	virtual_avail = (vm_offset_t) KERNBASE + firstaddr;
	virtual_avail = pmap_kmem_choose(virtual_avail);

	virtual_end = VM_MAX_KERNEL_ADDRESS;

	/*
	 * Initialize the kernel pmap (which is statically allocated).
	 */
	PMAP_LOCK_INIT(kernel_pmap);
	kernel_pmap->pm_pdir = (pd_entry_t *) (KERNBASE + (u_int)IdlePTD);
#ifdef PAE
	kernel_pmap->pm_pdpt = (pdpt_entry_t *) (KERNBASE + (u_int)IdlePDPT);
#endif
	kernel_pmap->pm_root = NULL;
	kernel_pmap->pm_active = -1;	/* don't allow deactivation */
	TAILQ_INIT(&kernel_pmap->pm_pvchunk);
	LIST_INIT(&allpmaps);
	mtx_init(&allpmaps_lock, "allpmaps", NULL, MTX_SPIN);
	mtx_lock_spin(&allpmaps_lock);
	LIST_INSERT_HEAD(&allpmaps, kernel_pmap, pm_list);
	mtx_unlock_spin(&allpmaps_lock);
	nkpt = NKPT;

	/*
	 * Reserve some special page table entries/VA space for temporary
	 * mapping of pages.
	 */
#define	SYSMAP(c, p, v, n)	\
	v = (c)va; va += ((n)*PAGE_SIZE); p = pte; pte += (n);

	va = virtual_avail;
	pte = vtopte(va);

	/*
	 * CMAP1/CMAP2 are used for zeroing and copying pages.
	 * CMAP3 is used for the idle process page zeroing.
	 */
	for (i = 0; i < MAXCPU; i++) {
		sysmaps = &sysmaps_pcpu[i];
		mtx_init(&sysmaps->lock, "SYSMAPS", NULL, MTX_DEF);
		SYSMAP(caddr_t, sysmaps->CMAP1, sysmaps->CADDR1, 1)
		SYSMAP(caddr_t, sysmaps->CMAP2, sysmaps->CADDR2, 1)
	}
	SYSMAP(caddr_t, CMAP1, CADDR1, 1)
	SYSMAP(caddr_t, CMAP3, CADDR3, 1)
	*CMAP3 = 0;

	/*
	 * Crashdump maps.
	 */
	SYSMAP(caddr_t, unused, crashdumpmap, MAXDUMPPGS)

	/*
	 * ptvmmap is used for reading arbitrary physical pages via /dev/mem.
	 */
	SYSMAP(caddr_t, unused, ptvmmap, 1)

	/*
	 * msgbufp is used to map the system message buffer.
	 */
	SYSMAP(struct msgbuf *, unused, msgbufp, atop(round_page(MSGBUF_SIZE)))

	/*
	 * ptemap is used for pmap_pte_quick
	 */
	SYSMAP(pt_entry_t *, PMAP1, PADDR1, 1);
	SYSMAP(pt_entry_t *, PMAP2, PADDR2, 1);

	mtx_init(&PMAP2mutex, "PMAP2", NULL, MTX_DEF);

	virtual_avail = va;

	*CMAP1 = 0;

	/*
	 * Leave in place an identity mapping (virt == phys) for the low 1 MB
	 * physical memory region that is used by the ACPI wakeup code.  This
	 * mapping must not have PG_G set.
	 */
#ifdef XBOX
	/* FIXME: This is gross, but needed for the XBOX. Since we are in such
	 * an early stadium, we cannot yet neatly map video memory ... :-(
	 * Better fixes are very welcome! */
	if (!arch_i386_is_xbox)
#endif
	for (i = 1; i < NKPT; i++)
		PTD[i] = 0;

	/* Initialize the PAT MSR if present. */
	pmap_init_pat();

	/* Turn on PG_G on kernel page(s) */
	pmap_set_pg();
}

/*
 * Setup the PAT MSR.
 */
void
pmap_init_pat(void)
{
	uint64_t pat_msr;

	/* Bail if this CPU doesn't implement PAT. */
	if (!(cpu_feature & CPUID_PAT))
		return;

	if (cpu_vendor_id != CPU_VENDOR_INTEL ||
	    (I386_CPU_FAMILY(cpu_id) == 6 && I386_CPU_MODEL(cpu_id) >= 0xe)) {
		/*
		 * Leave the indices 0-3 at the default of WB, WT, UC, and UC-.
		 * Program 4 and 5 as WP and WC.
		 * Leave 6 and 7 as UC and UC-.
		 */
		pat_msr = rdmsr(MSR_PAT);
		pat_msr &= ~(PAT_MASK(4) | PAT_MASK(5));
		pat_msr |= PAT_VALUE(4, PAT_WRITE_PROTECTED) |
		    PAT_VALUE(5, PAT_WRITE_COMBINING);
		pat_works = 1;
	} else {
		/*
		 * Due to some Intel errata, we can only safely use the lower 4
		 * PAT entries.  Thus, just replace PAT Index 2 with WC instead
		 * of UC-.
		 *
		 *   Intel Pentium III Processor Specification Update
		 * Errata E.27 (Upper Four PAT Entries Not Usable With Mode B
		 * or Mode C Paging)
		 *
		 *   Intel Pentium IV  Processor Specification Update
		 * Errata N46 (PAT Index MSB May Be Calculated Incorrectly)
		 */
		pat_msr = rdmsr(MSR_PAT);
		pat_msr &= ~PAT_MASK(2);
		pat_msr |= PAT_VALUE(2, PAT_WRITE_COMBINING);
		pat_works = 0;
	}
	wrmsr(MSR_PAT, pat_msr);
}

/*
 * Set PG_G on kernel pages.  Only the BSP calls this when SMP is turned on.
 */
void
pmap_set_pg(void)
{
	pd_entry_t pdir;
	pt_entry_t *pte;
	vm_offset_t va, endva;
	int i;

	if (pgeflag == 0)
		return;

	i = KERNLOAD/NBPDR;
	endva = KERNBASE + KERNend;

	if (pseflag) {
		va = KERNBASE + KERNLOAD;
		while (va  < endva) {
			pdir = kernel_pmap->pm_pdir[KPTDI+i];
			pdir |= pgeflag;
			kernel_pmap->pm_pdir[KPTDI+i] = PTD[KPTDI+i] = pdir;
			invltlb();	/* Play it safe, invltlb() every time */
			i++;
			va += NBPDR;
		}
	} else {
		va = (vm_offset_t)btext;
		while (va < endva) {
			pte = vtopte(va);
			if (*pte)
				*pte |= pgeflag;
			invltlb();	/* Play it safe, invltlb() every time */
			va += PAGE_SIZE;
		}
	}
}

/*
 * Initialize a vm_page's machine-dependent fields.
 */
void
pmap_page_init(vm_page_t m)
{

	TAILQ_INIT(&m->md.pv_list);
}

#ifdef PAE

static MALLOC_DEFINE(M_PMAPPDPT, "pmap", "pmap pdpt");

static void *
pmap_pdpt_allocf(uma_zone_t zone, int bytes, u_int8_t *flags, int wait)
{

	/* Inform UMA that this allocator uses kernel_map/object. */
	*flags = UMA_SLAB_KERNEL;
	return (contigmalloc(PAGE_SIZE, M_PMAPPDPT, 0, 0x0ULL, 0xffffffffULL,
	    1, 0));
}
#endif

/*
 * ABuse the pte nodes for unmapped kva to thread a kva freelist through.
 * Requirements:
 *  - Must deal with pages in order to ensure that none of the PG_* bits
 *    are ever set, PG_V in particular.
 *  - Assumes we can write to ptes without pte_store() atomic ops, even
 *    on PAE systems.  This should be ok.
 *  - Assumes nothing will ever test these addresses for 0 to indicate
 *    no mapping instead of correctly checking PG_V.
 *  - Assumes a vm_offset_t will fit in a pte (true for i386).
 * Because PG_V is never set, there can be no mappings to invalidate.
 */
static vm_offset_t
pmap_ptelist_alloc(vm_offset_t *head)
{
	pt_entry_t *pte;
	vm_offset_t va;

	va = *head;
	if (va == 0)
		return (va);	/* Out of memory */
	pte = vtopte(va);
	*head = *pte;
	if (*head & PG_V)
		panic("pmap_ptelist_alloc: va with PG_V set!");
	*pte = 0;
	return (va);
}

static void
pmap_ptelist_free(vm_offset_t *head, vm_offset_t va)
{
	pt_entry_t *pte;

	if (va & PG_V)
		panic("pmap_ptelist_free: freeing va with PG_V set!");
	pte = vtopte(va);
	*pte = *head;		/* virtual! PG_V is 0 though */
	*head = va;
}

static void
pmap_ptelist_init(vm_offset_t *head, void *base, int npages)
{
	int i;
	vm_offset_t va;

	*head = 0;
	for (i = npages - 1; i >= 0; i--) {
		va = (vm_offset_t)base + i * PAGE_SIZE;
		pmap_ptelist_free(head, va);
	}
}


/*
 *	Initialize the pmap module.
 *	Called by vm_init, to initialize any structures that the pmap
 *	system needs to map virtual memory.
 */
void
pmap_init(void)
{
	vm_page_t mpte;
	vm_size_t s;
	int i, pv_npg;

	/*
	 * Initialize the vm page array entries for the kernel pmap's
	 * page table pages.
	 */
	for (i = 0; i < nkpt; i++) {
		mpte = PHYS_TO_VM_PAGE(PTD[i + KPTDI] & PG_FRAME);
		KASSERT(mpte >= vm_page_array &&
		    mpte < &vm_page_array[vm_page_array_size],
		    ("pmap_init: page table page is out of range"));
		mpte->pindex = i + KPTDI;
		mpte->phys_addr = PTD[i + KPTDI] & PG_FRAME;
	}

	/*
	 * Initialize the address space (zone) for the pv entries.  Set a
	 * high water mark so that the system can recover from excessive
	 * numbers of pv entries.
	 */
	TUNABLE_INT_FETCH("vm.pmap.shpgperproc", &shpgperproc);
	pv_entry_max = shpgperproc * maxproc + cnt.v_page_count;
	TUNABLE_INT_FETCH("vm.pmap.pv_entries", &pv_entry_max);
	pv_entry_max = roundup(pv_entry_max, _NPCPV);
	pv_entry_high_water = 9 * (pv_entry_max / 10);

	/*
	 * Are large page mappings enabled?
	 */
	TUNABLE_INT_FETCH("vm.pmap.pg_ps_enabled", &pg_ps_enabled);

	/*
	 * Calculate the size of the pv head table for superpages.
	 */
	for (i = 0; phys_avail[i + 1]; i += 2);
	pv_npg = round_4mpage(phys_avail[(i - 2) + 1]) / NBPDR;

	/*
	 * Allocate memory for the pv head table for superpages.
	 */
	s = (vm_size_t)(pv_npg * sizeof(struct md_page));
	s = round_page(s);
	pv_table = (struct md_page *)kmem_alloc(kernel_map, s);
	for (i = 0; i < pv_npg; i++)
		TAILQ_INIT(&pv_table[i].pv_list);

	pv_maxchunks = MAX(pv_entry_max / _NPCPV, maxproc);
	pv_chunkbase = (struct pv_chunk *)kmem_alloc_nofault(kernel_map,
	    PAGE_SIZE * pv_maxchunks);
	if (pv_chunkbase == NULL)
		panic("pmap_init: not enough kvm for pv chunks");
	pmap_ptelist_init(&pv_vafree, pv_chunkbase, pv_maxchunks);
#ifdef PAE
	pdptzone = uma_zcreate("PDPT", NPGPTD * sizeof(pdpt_entry_t), NULL,
	    NULL, NULL, NULL, (NPGPTD * sizeof(pdpt_entry_t)) - 1,
	    UMA_ZONE_VM | UMA_ZONE_NOFREE);
	uma_zone_set_allocf(pdptzone, pmap_pdpt_allocf);
#endif
}


SYSCTL_INT(_vm_pmap, OID_AUTO, pv_entry_max, CTLFLAG_RD, &pv_entry_max, 0,
	"Max number of PV entries");
SYSCTL_INT(_vm_pmap, OID_AUTO, shpgperproc, CTLFLAG_RD, &shpgperproc, 0,
	"Page share factor per proc");

SYSCTL_NODE(_vm_pmap, OID_AUTO, pde, CTLFLAG_RD, 0,
    "2/4MB page mapping counters");

static u_long pmap_pde_demotions;
SYSCTL_ULONG(_vm_pmap_pde, OID_AUTO, demotions, CTLFLAG_RD,
    &pmap_pde_demotions, 0, "2/4MB page demotions");

static u_long pmap_pde_mappings;
SYSCTL_ULONG(_vm_pmap_pde, OID_AUTO, mappings, CTLFLAG_RD,
    &pmap_pde_mappings, 0, "2/4MB page mappings");

static u_long pmap_pde_p_failures;
SYSCTL_ULONG(_vm_pmap_pde, OID_AUTO, p_failures, CTLFLAG_RD,
    &pmap_pde_p_failures, 0, "2/4MB page promotion failures");

static u_long pmap_pde_promotions;
SYSCTL_ULONG(_vm_pmap_pde, OID_AUTO, promotions, CTLFLAG_RD,
    &pmap_pde_promotions, 0, "2/4MB page promotions");

/***************************************************
 * Low level helper routines.....
 ***************************************************/

/*
 * Determine the appropriate bits to set in a PTE or PDE for a specified
 * caching mode.
 */
static int
pmap_cache_bits(int mode, boolean_t is_pde)
{
	int pat_flag, pat_index, cache_bits;

	/* The PAT bit is different for PTE's and PDE's. */
	pat_flag = is_pde ? PG_PDE_PAT : PG_PTE_PAT;

	/* If we don't support PAT, map extended modes to older ones. */
	if (!(cpu_feature & CPUID_PAT)) {
		switch (mode) {
		case PAT_UNCACHEABLE:
		case PAT_WRITE_THROUGH:
		case PAT_WRITE_BACK:
			break;
		case PAT_UNCACHED:
		case PAT_WRITE_COMBINING:
		case PAT_WRITE_PROTECTED:
			mode = PAT_UNCACHEABLE;
			break;
		}
	}

	/* Map the caching mode to a PAT index. */
	if (pat_works) {
		switch (mode) {
		case PAT_UNCACHEABLE:
			pat_index = 3;
			break;
		case PAT_WRITE_THROUGH:
			pat_index = 1;
			break;
		case PAT_WRITE_BACK:
			pat_index = 0;
			break;
		case PAT_UNCACHED:
			pat_index = 2;
			break;
		case PAT_WRITE_COMBINING:
			pat_index = 5;
			break;
		case PAT_WRITE_PROTECTED:
			pat_index = 4;
			break;
		default:
			panic("Unknown caching mode %d\n", mode);
		}
	} else {
		switch (mode) {
		case PAT_UNCACHED:
		case PAT_UNCACHEABLE:
		case PAT_WRITE_PROTECTED:
			pat_index = 3;
			break;
		case PAT_WRITE_THROUGH:
			pat_index = 1;
			break;
		case PAT_WRITE_BACK:
			pat_index = 0;
			break;
		case PAT_WRITE_COMBINING:
			pat_index = 2;
			break;
		default:
			panic("Unknown caching mode %d\n", mode);
		}
	}

	/* Map the 3-bit index value into the PAT, PCD, and PWT bits. */
	cache_bits = 0;
	if (pat_index & 0x4)
		cache_bits |= pat_flag;
	if (pat_index & 0x2)
		cache_bits |= PG_NC_PCD;
	if (pat_index & 0x1)
		cache_bits |= PG_NC_PWT;
	return (cache_bits);
}
#ifdef SMP
/*
 * For SMP, these functions have to use the IPI mechanism for coherence.
 *
 * N.B.: Before calling any of the following TLB invalidation functions,
 * the calling processor must ensure that all stores updating a non-
 * kernel page table are globally performed.  Otherwise, another
 * processor could cache an old, pre-update entry without being
 * invalidated.  This can happen one of two ways: (1) The pmap becomes
 * active on another processor after its pm_active field is checked by
 * one of the following functions but before a store updating the page
 * table is globally performed. (2) The pmap becomes active on another
 * processor before its pm_active field is checked but due to
 * speculative loads one of the following functions stills reads the
 * pmap as inactive on the other processor.
 *
 * The kernel page table is exempt because its pm_active field is
 * immutable.  The kernel page table is always active on every
 * processor.
 */
void
pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
{
	u_int cpumask;
	u_int other_cpus;

	sched_pin();
	if (pmap == kernel_pmap || pmap->pm_active == all_cpus) {
		invlpg(va);
		smp_invlpg(va);
	} else {
		cpumask = PCPU_GET(cpumask);
		other_cpus = PCPU_GET(other_cpus);
		if (pmap->pm_active & cpumask)
			invlpg(va);
		if (pmap->pm_active & other_cpus)
			smp_masked_invlpg(pmap->pm_active & other_cpus, va);
	}
	sched_unpin();
}

void
pmap_invalidate_range(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
{
	u_int cpumask;
	u_int other_cpus;
	vm_offset_t addr;

	sched_pin();
	if (pmap == kernel_pmap || pmap->pm_active == all_cpus) {
		for (addr = sva; addr < eva; addr += PAGE_SIZE)
			invlpg(addr);
		smp_invlpg_range(sva, eva);
	} else {
		cpumask = PCPU_GET(cpumask);
		other_cpus = PCPU_GET(other_cpus);
		if (pmap->pm_active & cpumask)
			for (addr = sva; addr < eva; addr += PAGE_SIZE)
				invlpg(addr);
		if (pmap->pm_active & other_cpus)
			smp_masked_invlpg_range(pmap->pm_active & other_cpus,
			    sva, eva);
	}
	sched_unpin();
}

void
pmap_invalidate_all(pmap_t pmap)
{
	u_int cpumask;
	u_int other_cpus;

	sched_pin();
	if (pmap == kernel_pmap || pmap->pm_active == all_cpus) {
		invltlb();
		smp_invltlb();
	} else {
		cpumask = PCPU_GET(cpumask);
		other_cpus = PCPU_GET(other_cpus);
		if (pmap->pm_active & cpumask)
			invltlb();
		if (pmap->pm_active & other_cpus)
			smp_masked_invltlb(pmap->pm_active & other_cpus);
	}
	sched_unpin();
}

void
pmap_invalidate_cache(void)
{

	sched_pin();
	wbinvd();
	smp_cache_flush();
	sched_unpin();
}
#else /* !SMP */
/*
 * Normal, non-SMP, 486+ invalidation functions.
 * We inline these within pmap.c for speed.
 */
PMAP_INLINE void
pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
{

	if (pmap == kernel_pmap || pmap->pm_active)
		invlpg(va);
}

PMAP_INLINE void
pmap_invalidate_range(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
{
	vm_offset_t addr;

	if (pmap == kernel_pmap || pmap->pm_active)
		for (addr = sva; addr < eva; addr += PAGE_SIZE)
			invlpg(addr);
}

PMAP_INLINE void
pmap_invalidate_all(pmap_t pmap)
{

	if (pmap == kernel_pmap || pmap->pm_active)
		invltlb();
}

PMAP_INLINE void
pmap_invalidate_cache(void)
{

	wbinvd();
}
#endif /* !SMP */

/*
 * Are we current address space or kernel?  N.B. We return FALSE when
 * a pmap's page table is in use because a kernel thread is borrowing
 * it.  The borrowed page table can change spontaneously, making any
 * dependence on its continued use subject to a race condition.
 */
static __inline int
pmap_is_current(pmap_t pmap)
{

	return (pmap == kernel_pmap ||
		(pmap == vmspace_pmap(curthread->td_proc->p_vmspace) &&
	    (pmap->pm_pdir[PTDPTDI] & PG_FRAME) == (PTDpde[0] & PG_FRAME)));
}

/*
 * If the given pmap is not the current or kernel pmap, the returned pte must
 * be released by passing it to pmap_pte_release().
 */
pt_entry_t *
pmap_pte(pmap_t pmap, vm_offset_t va)
{
	pd_entry_t newpf;
	pd_entry_t *pde;

	pde = pmap_pde(pmap, va);
	if (*pde & PG_PS)
		return (pde);
	if (*pde != 0) {
		/* are we current address space or kernel? */
		if (pmap_is_current(pmap))
			return (vtopte(va));
		mtx_lock(&PMAP2mutex);
		newpf = *pde & PG_FRAME;
		if ((*PMAP2 & PG_FRAME) != newpf) {
			*PMAP2 = newpf | PG_RW | PG_V | PG_A | PG_M;
			pmap_invalidate_page(kernel_pmap, (vm_offset_t)PADDR2);
		}
		return (PADDR2 + (i386_btop(va) & (NPTEPG - 1)));
	}
	return (0);
}

/*
 * Releases a pte that was obtained from pmap_pte().  Be prepared for the pte
 * being NULL.
 */
static __inline void
pmap_pte_release(pt_entry_t *pte)
{

	if ((pt_entry_t *)((vm_offset_t)pte & ~PAGE_MASK) == PADDR2)
		mtx_unlock(&PMAP2mutex);
}

static __inline void
invlcaddr(void *caddr)
{

	invlpg((u_int)caddr);
}

/*
 * Super fast pmap_pte routine best used when scanning
 * the pv lists.  This eliminates many coarse-grained
 * invltlb calls.  Note that many of the pv list
 * scans are across different pmaps.  It is very wasteful
 * to do an entire invltlb for checking a single mapping.
 *
 * If the given pmap is not the current pmap, vm_page_queue_mtx
 * must be held and curthread pinned to a CPU.
 */
static pt_entry_t *
pmap_pte_quick(pmap_t pmap, vm_offset_t va)
{
	pd_entry_t newpf;
	pd_entry_t *pde;

	pde = pmap_pde(pmap, va);
	if (*pde & PG_PS)
		return (pde);
	if (*pde != 0) {
		/* are we current address space or kernel? */
		if (pmap_is_current(pmap))
			return (vtopte(va));
		mtx_assert(&vm_page_queue_mtx, MA_OWNED);
		KASSERT(curthread->td_pinned > 0, ("curthread not pinned"));
		newpf = *pde & PG_FRAME;
		if ((*PMAP1 & PG_FRAME) != newpf) {
			*PMAP1 = newpf | PG_RW | PG_V | PG_A | PG_M;
#ifdef SMP
			PMAP1cpu = PCPU_GET(cpuid);
#endif
			invlcaddr(PADDR1);
			PMAP1changed++;
		} else
#ifdef SMP
		if (PMAP1cpu != PCPU_GET(cpuid)) {
			PMAP1cpu = PCPU_GET(cpuid);
			invlcaddr(PADDR1);
			PMAP1changedcpu++;
		} else
#endif
			PMAP1unchanged++;
		return (PADDR1 + (i386_btop(va) & (NPTEPG - 1)));
	}
	return (0);
}

/*
 *	Routine:	pmap_extract
 *	Function:
 *		Extract the physical page address associated
 *		with the given map/virtual_address pair.
 */
vm_paddr_t
pmap_extract(pmap_t pmap, vm_offset_t va)
{
	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);
		}
	}
	PMAP_UNLOCK(pmap);
	return (rtval);
}

/*
 *	Routine:	pmap_extract_and_hold
 *	Function:
 *		Atomically extract and hold the physical page
 *		with the given pmap and virtual address pair
 *		if that mapping permits the given protection.
 */
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;
	vm_page_t m;

	m = NULL;
	vm_page_lock_queues();
	PMAP_LOCK(pmap);
	pde = *pmap_pde(pmap, va);
	if (pde != 0) {
		if (pde & PG_PS) {
			if ((pde & PG_RW) || (prot & VM_PROT_WRITE) == 0) {
				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)) {
				m = PHYS_TO_VM_PAGE(pte & PG_FRAME);
				vm_page_hold(m);
			}
			sched_unpin();
		}
	}
	vm_page_unlock_queues();
	PMAP_UNLOCK(pmap);
	return (m);
}

/***************************************************
 * Low level mapping routines.....
 ***************************************************/

/*
 * Add a wired page to the kva.
 * Note: not SMP coherent.
 */
PMAP_INLINE void
pmap_kenter(vm_offset_t va, vm_paddr_t pa)
{
	pt_entry_t *pte;

	pte = vtopte(va);
	pte_store(pte, pa | PG_RW | PG_V | pgeflag);
}

static __inline void
pmap_kenter_attr(vm_offset_t va, vm_paddr_t pa, int mode)
{
	pt_entry_t *pte;

	pte = vtopte(va);
	pte_store(pte, pa | PG_RW | PG_V | pgeflag | pmap_cache_bits(mode, 0));
}

/*
 * Remove a page from the kernel pagetables.
 * Note: not SMP coherent.
 */
PMAP_INLINE void
pmap_kremove(vm_offset_t va)
{
	pt_entry_t *pte;

	pte = vtopte(va);
	pte_clear(pte);
}

/*
 *	Used to map a range of physical addresses into kernel
 *	virtual address space.
 *
 *	The value passed in '*virt' is a suggested virtual address for
 *	the mapping. Architectures which can support a direct-mapped
 *	physical to virtual region can return the appropriate address
 *	within that region, leaving '*virt' unchanged. Other
 *	architectures should map the pages starting at '*virt' and
 *	update '*virt' with the first usable address after the mapped
 *	region.
 */
vm_offset_t
pmap_map(vm_offset_t *virt, vm_paddr_t start, vm_paddr_t end, int prot)
{
	vm_offset_t va, sva;

	va = sva = *virt;
	while (start < end) {
		pmap_kenter(va, start);
		va += PAGE_SIZE;
		start += PAGE_SIZE;
	}
	pmap_invalidate_range(kernel_pmap, sva, va);
	*virt = va;
	return (sva);
}


/*
 * Add a list of wired pages to the kva
 * this routine is only used for temporary
 * kernel mappings that do not need to have
 * page modification or references recorded.
 * Note that old mappings are simply written
 * over.  The page *must* be wired.
 * Note: SMP coherent.  Uses a ranged shootdown IPI.
 */
void
pmap_qenter(vm_offset_t sva, vm_page_t *ma, int count)
{
	pt_entry_t *endpte, oldpte, *pte;

	oldpte = 0;
	pte = vtopte(sva);
	endpte = pte + count;
	while (pte < endpte) {
		oldpte |= *pte;
		pte_store(pte, VM_PAGE_TO_PHYS(*ma) | pgeflag | PG_RW | PG_V);
		pte++;
		ma++;
	}
	if ((oldpte & PG_V) != 0)
		pmap_invalidate_range(kernel_pmap, sva, sva + count *
		    PAGE_SIZE);
}

/*
 * This routine tears out page mappings from the
 * kernel -- it is meant only for temporary mappings.
 * Note: SMP coherent.  Uses a ranged shootdown IPI.
 */
void
pmap_qremove(vm_offset_t sva, int count)
{
	vm_offset_t va;

	va = sva;
	while (count-- > 0) {
		pmap_kremove(va);
		va += PAGE_SIZE;
	}
	pmap_invalidate_range(kernel_pmap, sva, va);
}

/***************************************************
 * Page table page management routines.....
 ***************************************************/
static __inline void
pmap_free_zero_pages(vm_page_t free)
{
	vm_page_t m;

	while (free != NULL) {
		m = free;
		free = m->right;
		/* Preserve the page's PG_ZERO setting. */
		vm_page_free_toq(m);
	}
}

/*
 * Schedule the specified unused page table page to be freed.  Specifically,
 * add the page to the specified list of pages that will be released to the
 * physical memory manager after the TLB has been updated.
 */
static __inline void
pmap_add_delayed_free_list(vm_page_t m, vm_page_t *free, boolean_t set_PG_ZERO)
{

	if (set_PG_ZERO)
		m->flags |= PG_ZERO;
	else
		m->flags &= ~PG_ZERO;
	m->right = *free;
	*free = m;
}

/*
 * Inserts the specified page table page into the specified pmap's collection
 * of idle page table pages.  Each of a pmap's page table pages is responsible
 * for mapping a distinct range of virtual addresses.  The pmap's collection is
 * ordered by this virtual address range.
 */
static void
pmap_insert_pt_page(pmap_t pmap, vm_page_t mpte)
{
	vm_page_t root;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	root = pmap->pm_root;
	if (root == NULL) {
		mpte->left = NULL;
		mpte->right = NULL;
	} else {
		root = vm_page_splay(mpte->pindex, root);
		if (mpte->pindex < root->pindex) {
			mpte->left = root->left;
			mpte->right = root;
			root->left = NULL;
		} else if (mpte->pindex == root->pindex)
			panic("pmap_insert_pt_page: pindex already inserted");
		else {
			mpte->right = root->right;
			mpte->left = root;
			root->right = NULL;
		}
	}
	pmap->pm_root = mpte;
}

/*
 * Looks for a page table page mapping the specified virtual address in the
 * specified pmap's collection of idle page table pages.  Returns NULL if there
 * is no page table page corresponding to the specified virtual address.
 */
static vm_page_t
pmap_lookup_pt_page(pmap_t pmap, vm_offset_t va)
{
	vm_page_t mpte;
	vm_pindex_t pindex = va >> PDRSHIFT;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	if ((mpte = pmap->pm_root) != NULL && mpte->pindex != pindex) {
		mpte = vm_page_splay(pindex, mpte);
		if ((pmap->pm_root = mpte)->pindex != pindex)
			mpte = NULL;
	}
	return (mpte);
}

/*
 * Removes the specified page table page from the specified pmap's collection
 * of idle page table pages.  The specified page table page must be a member of
 * the pmap's collection.
 */
static void
pmap_remove_pt_page(pmap_t pmap, vm_page_t mpte)
{
	vm_page_t root;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	if (mpte != pmap->pm_root)
		vm_page_splay(mpte->pindex, pmap->pm_root);
	if (mpte->left == NULL)
		root = mpte->right;
	else {
		root = vm_page_splay(mpte->pindex, mpte->left);
		root->right = mpte->right;
	}
	pmap->pm_root = root;
}

/*
 * This routine unholds page table pages, and if the hold count
 * drops to zero, then it decrements the wire count.
 */
static __inline int
pmap_unwire_pte_hold(pmap_t pmap, vm_page_t m, vm_page_t *free)
{

	--m->wire_count;
	if (m->wire_count == 0)
		return _pmap_unwire_pte_hold(pmap, m, free);
	else
		return 0;
}

static int
_pmap_unwire_pte_hold(pmap_t pmap, vm_page_t m, vm_page_t *free)
{
	vm_offset_t pteva;

	/*
	 * unmap the page table page
	 */
	pmap->pm_pdir[m->pindex] = 0;
	--pmap->pm_stats.resident_count;

	/*
	 * This is a release store so that the ordinary store unmapping
	 * the page table page is globally performed before TLB shoot-
	 * down is begun.
	 */
	atomic_subtract_rel_int(&cnt.v_wire_count, 1);

	/*
	 * Do an invltlb to make the invalidated mapping
	 * take effect immediately.
	 */
	pteva = VM_MAXUSER_ADDRESS + i386_ptob(m->pindex);
	pmap_invalidate_page(pmap, pteva);

	/*
	 * Put page on a list so that it is released after
	 * *ALL* TLB shootdown is done
	 */
	pmap_add_delayed_free_list(m, free, TRUE);

	return 1;
}

/*
 * After removing a page table entry, this routine is used to
 * conditionally free the page, and manage the hold/wire counts.
 */
static int
pmap_unuse_pt(pmap_t pmap, vm_offset_t va, vm_page_t *free)
{
	pd_entry_t ptepde;
	vm_page_t mpte;

	if (va >= VM_MAXUSER_ADDRESS)
		return 0;
	ptepde = *pmap_pde(pmap, va);
	mpte = PHYS_TO_VM_PAGE(ptepde & PG_FRAME);
	return pmap_unwire_pte_hold(pmap, mpte, free);
}

void
pmap_pinit0(pmap_t pmap)
{

	PMAP_LOCK_INIT(pmap);
	pmap->pm_pdir = (pd_entry_t *)(KERNBASE + (vm_offset_t)IdlePTD);
#ifdef PAE
	pmap->pm_pdpt = (pdpt_entry_t *)(KERNBASE + (vm_offset_t)IdlePDPT);
#endif
	pmap->pm_root = NULL;
	pmap->pm_active = 0;
	PCPU_SET(curpmap, pmap);
	TAILQ_INIT(&pmap->pm_pvchunk);
	bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
	mtx_lock_spin(&allpmaps_lock);
	LIST_INSERT_HEAD(&allpmaps, pmap, pm_list);
	mtx_unlock_spin(&allpmaps_lock);
}

/*
 * Initialize a preallocated and zeroed pmap structure,
 * such as one in a vmspace structure.
 */
int
pmap_pinit(pmap_t pmap)
{
	vm_page_t m, ptdpg[NPGPTD];
	vm_paddr_t pa;
	static int color;
	int i;

	PMAP_LOCK_INIT(pmap);

	/*
	 * No need to allocate page table space yet but we do need a valid
	 * page directory table.
	 */
	if (pmap->pm_pdir == NULL) {
		pmap->pm_pdir = (pd_entry_t *)kmem_alloc_nofault(kernel_map,
		    NBPTD);

		if (pmap->pm_pdir == NULL) {
			PMAP_LOCK_DESTROY(pmap);
			return (0);
		}
#ifdef PAE
		pmap->pm_pdpt = uma_zalloc(pdptzone, M_WAITOK | M_ZERO);
		KASSERT(((vm_offset_t)pmap->pm_pdpt &
		    ((NPGPTD * sizeof(pdpt_entry_t)) - 1)) == 0,
		    ("pmap_pinit: pdpt misaligned"));
		KASSERT(pmap_kextract((vm_offset_t)pmap->pm_pdpt) < (4ULL<<30),
		    ("pmap_pinit: pdpt above 4g"));
#endif
		pmap->pm_root = NULL;
	}
	KASSERT(pmap->pm_root == NULL,
	    ("pmap_pinit: pmap has reserved page table page(s)"));

	/*
	 * allocate the page directory page(s)
	 */
	for (i = 0; i < NPGPTD;) {
		m = vm_page_alloc(NULL, color++,
		    VM_ALLOC_NORMAL | VM_ALLOC_NOOBJ | VM_ALLOC_WIRED |
		    VM_ALLOC_ZERO);
		if (m == NULL)
			VM_WAIT;
		else {
			ptdpg[i++] = m;
		}
	}

	pmap_qenter((vm_offset_t)pmap->pm_pdir, ptdpg, NPGPTD);

	for (i = 0; i < NPGPTD; i++) {
		if ((ptdpg[i]->flags & PG_ZERO) == 0)
			bzero(pmap->pm_pdir + (i * NPDEPG), PAGE_SIZE);
	}

	mtx_lock_spin(&allpmaps_lock);
	LIST_INSERT_HEAD(&allpmaps, pmap, pm_list);
	mtx_unlock_spin(&allpmaps_lock);
	/* Wire in kernel global address entries. */
	bcopy(PTD + KPTDI, pmap->pm_pdir + KPTDI, nkpt * sizeof(pd_entry_t));

	/* install self-referential address mapping entry(s) */
	for (i = 0; i < NPGPTD; i++) {
		pa = VM_PAGE_TO_PHYS(ptdpg[i]);
		pmap->pm_pdir[PTDPTDI + i] = pa | PG_V | PG_RW | PG_A | PG_M;
#ifdef PAE
		pmap->pm_pdpt[i] = pa | PG_V;
#endif
	}

	pmap->pm_active = 0;
	TAILQ_INIT(&pmap->pm_pvchunk);
	bzero(&pmap->pm_stats, sizeof pmap->pm_stats);

	return (1);
}

/*
 * this routine is called if the page table page is not
 * mapped correctly.
 */
static vm_page_t
_pmap_allocpte(pmap_t pmap, unsigned ptepindex, int flags)
{
	vm_paddr_t ptepa;
	vm_page_t m;

	KASSERT((flags & (M_NOWAIT | M_WAITOK)) == M_NOWAIT ||
	    (flags & (M_NOWAIT | M_WAITOK)) == M_WAITOK,
	    ("_pmap_allocpte: flags is neither M_NOWAIT nor M_WAITOK"));

	/*
	 * Allocate a page table page.
	 */
	if ((m = vm_page_alloc(NULL, ptepindex, VM_ALLOC_NOOBJ |
	    VM_ALLOC_WIRED | VM_ALLOC_ZERO)) == NULL) {
		if (flags & M_WAITOK) {
			PMAP_UNLOCK(pmap);
			vm_page_unlock_queues();
			VM_WAIT;
			vm_page_lock_queues();
			PMAP_LOCK(pmap);
		}

		/*
		 * Indicate the need to retry.  While waiting, the page table
		 * page may have been allocated.
		 */
		return (NULL);
	}
	if ((m->flags & PG_ZERO) == 0)
		pmap_zero_page(m);

	/*
	 * Map the pagetable page into the process address space, if
	 * it isn't already there.
	 */

	pmap->pm_stats.resident_count++;

	ptepa = VM_PAGE_TO_PHYS(m);
	pmap->pm_pdir[ptepindex] =
		(pd_entry_t) (ptepa | PG_U | PG_RW | PG_V | PG_A | PG_M);

	return m;
}

static vm_page_t
pmap_allocpte(pmap_t pmap, vm_offset_t va, int flags)
{
	unsigned ptepindex;
	pd_entry_t ptepa;
	vm_page_t m;

	KASSERT((flags & (M_NOWAIT | M_WAITOK)) == M_NOWAIT ||
	    (flags & (M_NOWAIT | M_WAITOK)) == M_WAITOK,
	    ("pmap_allocpte: flags is neither M_NOWAIT nor M_WAITOK"));

	/*
	 * Calculate pagetable page index
	 */
	ptepindex = va >> PDRSHIFT;
retry:
	/*
	 * Get the page directory entry
	 */
	ptepa = pmap->pm_pdir[ptepindex];

	/*
	 * This supports switching from a 4MB page to a
	 * normal 4K page.
	 */
	if (ptepa & PG_PS) {
		(void)pmap_demote_pde(pmap, &pmap->pm_pdir[ptepindex], va);
		ptepa = pmap->pm_pdir[ptepindex];
	}

	/*
	 * If the page table page is mapped, we just increment the
	 * hold count, and activate it.
	 */
	if (ptepa) {
		m = PHYS_TO_VM_PAGE(ptepa & PG_FRAME);
		m->wire_count++;
	} else {
		/*
		 * Here if the pte page isn't mapped, or if it has
		 * been deallocated.
		 */
		m = _pmap_allocpte(pmap, ptepindex, flags);
		if (m == NULL && (flags & M_WAITOK))
			goto retry;
	}
	return (m);
}


/***************************************************
* Pmap allocation/deallocation routines.
 ***************************************************/

#ifdef SMP
/*
 * Deal with a SMP shootdown of other users of the pmap that we are
 * trying to dispose of.  This can be a bit hairy.
 */
static cpumask_t *lazymask;
static u_int lazyptd;
static volatile u_int lazywait;

void pmap_lazyfix_action(void);

void
pmap_lazyfix_action(void)
{
	cpumask_t mymask = PCPU_GET(cpumask);

#ifdef COUNT_IPIS
	(*ipi_lazypmap_counts[PCPU_GET(cpuid)])++;
#endif
	if (rcr3() == lazyptd)
		load_cr3(PCPU_GET(curpcb)->pcb_cr3);
	atomic_clear_int(lazymask, mymask);
	atomic_store_rel_int(&lazywait, 1);
}

static void
pmap_lazyfix_self(cpumask_t mymask)
{

	if (rcr3() == lazyptd)
		load_cr3(PCPU_GET(curpcb)->pcb_cr3);
	atomic_clear_int(lazymask, mymask);
}


static void
pmap_lazyfix(pmap_t pmap)
{
	cpumask_t mymask, mask;
	u_int spins;

	while ((mask = pmap->pm_active) != 0) {
		spins = 50000000;
		mask = mask & -mask;	/* Find least significant set bit */
		mtx_lock_spin(&smp_ipi_mtx);
#ifdef PAE
		lazyptd = vtophys(pmap->pm_pdpt);
#else
		lazyptd = vtophys(pmap->pm_pdir);
#endif
		mymask = PCPU_GET(cpumask);
		if (mask == mymask) {
			lazymask = &pmap->pm_active;
			pmap_lazyfix_self(mymask);
		} else {
			atomic_store_rel_int((u_int *)&lazymask,
			    (u_int)&pmap->pm_active);
			atomic_store_rel_int(&lazywait, 0);
			ipi_selected(mask, IPI_LAZYPMAP);
			while (lazywait == 0) {
				ia32_pause();
				if (--spins == 0)
					break;
			}
		}
		mtx_unlock_spin(&smp_ipi_mtx);
		if (spins == 0)
			printf("pmap_lazyfix: spun for 50000000\n");
	}
}

#else	/* SMP */

/*
 * Cleaning up on uniprocessor is easy.  For various reasons, we're
 * unlikely to have to even execute this code, including the fact
 * that the cleanup is deferred until the parent does a wait(2), which
 * means that another userland process has run.
 */
static void
pmap_lazyfix(pmap_t pmap)
{
	u_int cr3;

	cr3 = vtophys(pmap->pm_pdir);
	if (cr3 == rcr3()) {
		load_cr3(PCPU_GET(curpcb)->pcb_cr3);
		pmap->pm_active &= ~(PCPU_GET(cpumask));
	}
}
#endif	/* SMP */

/*
 * Release any resources held by the given physical map.
 * Called when a pmap initialized by pmap_pinit is being released.
 * Should only be called if the map contains no valid mappings.
 */
void
pmap_release(pmap_t pmap)
{
	vm_page_t m, ptdpg[NPGPTD];
	int i;

	KASSERT(pmap->pm_stats.resident_count == 0,
	    ("pmap_release: pmap resident count %ld != 0",
	    pmap->pm_stats.resident_count));
	KASSERT(pmap->pm_root == NULL,
	    ("pmap_release: pmap has reserved page table page(s)"));

	pmap_lazyfix(pmap);
	mtx_lock_spin(&allpmaps_lock);
	LIST_REMOVE(pmap, pm_list);
	mtx_unlock_spin(&allpmaps_lock);

	for (i = 0; i < NPGPTD; i++)
		ptdpg[i] = PHYS_TO_VM_PAGE(pmap->pm_pdir[PTDPTDI + i] &
		    PG_FRAME);

	bzero(pmap->pm_pdir + PTDPTDI, (nkpt + NPGPTD) *
	    sizeof(*pmap->pm_pdir));

	pmap_qremove((vm_offset_t)pmap->pm_pdir, NPGPTD);

	for (i = 0; i < NPGPTD; i++) {
		m = ptdpg[i];
#ifdef PAE
		KASSERT(VM_PAGE_TO_PHYS(m) == (pmap->pm_pdpt[i] & PG_FRAME),
		    ("pmap_release: got wrong ptd page"));
#endif
		m->wire_count--;
		atomic_subtract_int(&cnt.v_wire_count, 1);
		vm_page_free_zero(m);
	}
	PMAP_LOCK_DESTROY(pmap);
}

static int
kvm_size(SYSCTL_HANDLER_ARGS)
{
	unsigned long ksize = VM_MAX_KERNEL_ADDRESS - KERNBASE;

	return sysctl_handle_long(oidp, &ksize, 0, req);
}
SYSCTL_PROC(_vm, OID_AUTO, kvm_size, CTLTYPE_LONG|CTLFLAG_RD,
    0, 0, kvm_size, "IU", "Size of KVM");

static int
kvm_free(SYSCTL_HANDLER_ARGS)
{
	unsigned long kfree = VM_MAX_KERNEL_ADDRESS - kernel_vm_end;

	return sysctl_handle_long(oidp, &kfree, 0, req);
}
SYSCTL_PROC(_vm, OID_AUTO, kvm_free, CTLTYPE_LONG|CTLFLAG_RD,
    0, 0, kvm_free, "IU", "Amount of KVM free");

/*
 * grow the number of kernel page table entries, if needed
 */
void
pmap_growkernel(vm_offset_t addr)
{
	struct pmap *pmap;
	vm_paddr_t ptppaddr;
	vm_page_t nkpg;
	pd_entry_t newpdir;
	pt_entry_t *pde;

	mtx_assert(&kernel_map->system_mtx, MA_OWNED);
	if (kernel_vm_end == 0) {
		kernel_vm_end = KERNBASE;
		nkpt = 0;
		while (pdir_pde(PTD, kernel_vm_end)) {
			kernel_vm_end = (kernel_vm_end + PAGE_SIZE * NPTEPG) & ~(PAGE_SIZE * NPTEPG - 1);
			nkpt++;
			if (kernel_vm_end - 1 >= kernel_map->max_offset) {
				kernel_vm_end = kernel_map->max_offset;
				break;
			}
		}
	}
	addr = roundup2(addr, PAGE_SIZE * NPTEPG);
	if (addr - 1 >= kernel_map->max_offset)
		addr = kernel_map->max_offset;
	while (kernel_vm_end < addr) {
		if (pdir_pde(PTD, kernel_vm_end)) {
			kernel_vm_end = (kernel_vm_end + PAGE_SIZE * NPTEPG) & ~(PAGE_SIZE * NPTEPG - 1);
			if (kernel_vm_end - 1 >= kernel_map->max_offset) {
				kernel_vm_end = kernel_map->max_offset;
				break;
			}
			continue;
		}

		nkpg = vm_page_alloc(NULL, kernel_vm_end >> PDRSHIFT,
		    VM_ALLOC_INTERRUPT | VM_ALLOC_NOOBJ | VM_ALLOC_WIRED |
		    VM_ALLOC_ZERO);
		if (nkpg == NULL)
			panic("pmap_growkernel: no memory to grow kernel");

		nkpt++;

		if ((nkpg->flags & PG_ZERO) == 0)
			pmap_zero_page(nkpg);
		ptppaddr = VM_PAGE_TO_PHYS(nkpg);
		newpdir = (pd_entry_t) (ptppaddr | PG_V | PG_RW | PG_A | PG_M);
		pdir_pde(PTD, kernel_vm_end) = newpdir;

		mtx_lock_spin(&allpmaps_lock);
		LIST_FOREACH(pmap, &allpmaps, pm_list) {
			pde = pmap_pde(pmap, kernel_vm_end);
			pde_store(pde, newpdir);
		}
		mtx_unlock_spin(&allpmaps_lock);
		kernel_vm_end = (kernel_vm_end + PAGE_SIZE * NPTEPG) & ~(PAGE_SIZE * NPTEPG - 1);
		if (kernel_vm_end - 1 >= kernel_map->max_offset) {
			kernel_vm_end = kernel_map->max_offset;
			break;
		}
	}
}


/***************************************************
 * page management routines.
 ***************************************************/

CTASSERT(sizeof(struct pv_chunk) == PAGE_SIZE);
CTASSERT(_NPCM == 11);

static __inline struct pv_chunk *
pv_to_chunk(pv_entry_t pv)
{

	return (struct pv_chunk *)((uintptr_t)pv & ~(uintptr_t)PAGE_MASK);
}

#define PV_PMAP(pv) (pv_to_chunk(pv)->pc_pmap)

#define	PC_FREE0_9	0xfffffffful	/* Free values for index 0 through 9 */
#define	PC_FREE10	0x0000fffful	/* Free values for index 10 */

static uint32_t pc_freemask[11] = {
	PC_FREE0_9, PC_FREE0_9, PC_FREE0_9,
	PC_FREE0_9, PC_FREE0_9, PC_FREE0_9,
	PC_FREE0_9, PC_FREE0_9, PC_FREE0_9,
	PC_FREE0_9, PC_FREE10
};

SYSCTL_INT(_vm_pmap, OID_AUTO, pv_entry_count, CTLFLAG_RD, &pv_entry_count, 0,
	"Current number of pv entries");

#ifdef PV_STATS
static int pc_chunk_count, pc_chunk_allocs, pc_chunk_frees, pc_chunk_tryfail;

SYSCTL_INT(_vm_pmap, OID_AUTO, pc_chunk_count, CTLFLAG_RD, &pc_chunk_count, 0,
	"Current number of pv entry chunks");
SYSCTL_INT(_vm_pmap, OID_AUTO, pc_chunk_allocs, CTLFLAG_RD, &pc_chunk_allocs, 0,
	"Current number of pv entry chunks allocated");
SYSCTL_INT(_vm_pmap, OID_AUTO, pc_chunk_frees, CTLFLAG_RD, &pc_chunk_frees, 0,
	"Current number of pv entry chunks frees");
SYSCTL_INT(_vm_pmap, OID_AUTO, pc_chunk_tryfail, CTLFLAG_RD, &pc_chunk_tryfail, 0,
	"Number of times tried to get a chunk page but failed.");

static long pv_entry_frees, pv_entry_allocs;
static int pv_entry_spare;

SYSCTL_LONG(_vm_pmap, OID_AUTO, pv_entry_frees, CTLFLAG_RD, &pv_entry_frees, 0,
	"Current number of pv entry frees");
SYSCTL_LONG(_vm_pmap, OID_AUTO, pv_entry_allocs, CTLFLAG_RD, &pv_entry_allocs, 0,
	"Current number of pv entry allocs");
SYSCTL_INT(_vm_pmap, OID_AUTO, pv_entry_spare, CTLFLAG_RD, &pv_entry_spare, 0,
	"Current number of spare pv entries");

static int pmap_collect_inactive, pmap_collect_active;

SYSCTL_INT(_vm_pmap, OID_AUTO, pmap_collect_inactive, CTLFLAG_RD, &pmap_collect_inactive, 0,
	"Current number times pmap_collect called on inactive queue");
SYSCTL_INT(_vm_pmap, OID_AUTO, pmap_collect_active, CTLFLAG_RD, &pmap_collect_active, 0,
	"Current number times pmap_collect called on active queue");
#endif

/*
 * We are in a serious low memory condition.  Resort to
 * drastic measures to free some pages so we can allocate
 * another pv entry chunk.  This is normally called to
 * unmap inactive pages, and if necessary, active pages.
 */
static void
pmap_collect(pmap_t locked_pmap, struct vpgqueues *vpq)
{
	struct md_page *pvh;
	pd_entry_t *pde;
	pmap_t pmap;
	pt_entry_t *pte, tpte;
	pv_entry_t next_pv, pv;
	vm_offset_t va;
	vm_page_t m, free;

	sched_pin();
	TAILQ_FOREACH(m, &vpq->pl, pageq) {
		if (m->hold_count || m->busy)
			continue;
		TAILQ_FOREACH_SAFE(pv, &m->md.pv_list, pv_list, next_pv) {
			va = pv->pv_va;
			pmap = PV_PMAP(pv);
			/* Avoid deadlock and lock recursion. */
			if (pmap > locked_pmap)
				PMAP_LOCK(pmap);
			else if (pmap != locked_pmap && !PMAP_TRYLOCK(pmap))
				continue;
			pmap->pm_stats.resident_count--;
			pde = pmap_pde(pmap, va);
			KASSERT((*pde & PG_PS) == 0, ("pmap_collect: found"
			    " a 4mpage in page %p's pv list", m));
			pte = pmap_pte_quick(pmap, va);
			tpte = pte_load_clear(pte);
			KASSERT((tpte & PG_W) == 0,
			    ("pmap_collect: wired pte %#jx", (uintmax_t)tpte));
			if (tpte & PG_A)
				vm_page_flag_set(m, PG_REFERENCED);
			if ((tpte & (PG_M | PG_RW)) == (PG_M | PG_RW))
				vm_page_dirty(m);
			free = NULL;
			pmap_unuse_pt(pmap, va, &free);
			pmap_invalidate_page(pmap, va);
			pmap_free_zero_pages(free);
			TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
			if (TAILQ_EMPTY(&m->md.pv_list)) {
				pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
				if (TAILQ_EMPTY(&pvh->pv_list))
					vm_page_flag_clear(m, PG_WRITEABLE);
			}
			free_pv_entry(pmap, pv);
			if (pmap != locked_pmap)
				PMAP_UNLOCK(pmap);
		}
	}
	sched_unpin();
}


/*
 * free the pv_entry back to the free list
 */
static void
free_pv_entry(pmap_t pmap, pv_entry_t pv)
{
	vm_page_t m;
	struct pv_chunk *pc;
	int idx, field, bit;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	PV_STAT(pv_entry_frees++);
	PV_STAT(pv_entry_spare++);
	pv_entry_count--;
	pc = pv_to_chunk(pv);
	idx = pv - &pc->pc_pventry[0];
	field = idx / 32;
	bit = idx % 32;
	pc->pc_map[field] |= 1ul << bit;
	/* move to head of list */
	TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
	for (idx = 0; idx < _NPCM; idx++)
		if (pc->pc_map[idx] != pc_freemask[idx]) {
			TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
			return;
		}
	PV_STAT(pv_entry_spare -= _NPCPV);
	PV_STAT(pc_chunk_count--);
	PV_STAT(pc_chunk_frees++);
	/* entire chunk is free, return it */
	m = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)pc));
	pmap_qremove((vm_offset_t)pc, 1);
	vm_page_unwire(m, 0);
	vm_page_free(m);
	pmap_ptelist_free(&pv_vafree, (vm_offset_t)pc);
}

/*
 * get a new pv_entry, allocating a block from the system
 * when needed.
 */
static pv_entry_t
get_pv_entry(pmap_t pmap, int try)
{
	static const struct timeval printinterval = { 60, 0 };
	static struct timeval lastprint;
	static vm_pindex_t colour;
	struct vpgqueues *pq;
	int bit, field;
	pv_entry_t pv;
	struct pv_chunk *pc;
	vm_page_t m;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	PV_STAT(pv_entry_allocs++);
	pv_entry_count++;
	if (pv_entry_count > pv_entry_high_water)
		if (ratecheck(&lastprint, &printinterval))
			printf("Approaching the limit on PV entries, consider "
			    "increasing either the vm.pmap.shpgperproc or the "
			    "vm.pmap.pv_entry_max tunable.\n");
	pq = NULL;
retry:
	pc = TAILQ_FIRST(&pmap->pm_pvchunk);
	if (pc != NULL) {
		for (field = 0; field < _NPCM; field++) {
			if (pc->pc_map[field]) {
				bit = bsfl(pc->pc_map[field]);
				break;
			}
		}
		if (field < _NPCM) {
			pv = &pc->pc_pventry[field * 32 + bit];
			pc->pc_map[field] &= ~(1ul << bit);
			/* If this was the last item, move it to tail */
			for (field = 0; field < _NPCM; field++)
				if (pc->pc_map[field] != 0) {
					PV_STAT(pv_entry_spare--);
					return (pv);	/* not full, return */
				}
			TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
			TAILQ_INSERT_TAIL(&pmap->pm_pvchunk, pc, pc_list);
			PV_STAT(pv_entry_spare--);
			return (pv);
		}
	}
	/*
	 * Access to the ptelist "pv_vafree" is synchronized by the page
	 * queues lock.  If "pv_vafree" is currently non-empty, it will
	 * remain non-empty until pmap_ptelist_alloc() completes.
	 */
	if (pv_vafree == 0 || (m = vm_page_alloc(NULL, colour, (pq ==
	    &vm_page_queues[PQ_ACTIVE] ? VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL) |
	    VM_ALLOC_NOOBJ | VM_ALLOC_WIRED)) == NULL) {
		if (try) {
			pv_entry_count--;
			PV_STAT(pc_chunk_tryfail++);
			return (NULL);
		}
		/*
		 * Reclaim pv entries: At first, destroy mappings to
		 * inactive pages.  After that, if a pv chunk entry
		 * is still needed, destroy mappings to active pages.
		 */
		if (pq == NULL) {
			PV_STAT(pmap_collect_inactive++);
			pq = &vm_page_queues[PQ_INACTIVE];
		} else if (pq == &vm_page_queues[PQ_INACTIVE]) {
			PV_STAT(pmap_collect_active++);
			pq = &vm_page_queues[PQ_ACTIVE];
		} else
			panic("get_pv_entry: increase vm.pmap.shpgperproc");
		pmap_collect(pmap, pq);
		goto retry;
	}
	PV_STAT(pc_chunk_count++);
	PV_STAT(pc_chunk_allocs++);
	colour++;
	pc = (struct pv_chunk *)pmap_ptelist_alloc(&pv_vafree);
	pmap_qenter((vm_offset_t)pc, &m, 1);
	pc->pc_pmap = pmap;
	pc->pc_map[0] = pc_freemask[0] & ~1ul;	/* preallocated bit 0 */
	for (field = 1; field < _NPCM; field++)
		pc->pc_map[field] = pc_freemask[field];
	pv = &pc->pc_pventry[0];
	TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
	PV_STAT(pv_entry_spare += _NPCPV - 1);
	return (pv);
}

static __inline pv_entry_t
pmap_pvh_remove(struct md_page *pvh, pmap_t pmap, vm_offset_t va)
{
	pv_entry_t pv;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	TAILQ_FOREACH(pv, &pvh->pv_list, pv_list) {
		if (pmap == PV_PMAP(pv) && va == pv->pv_va) {
			TAILQ_REMOVE(&pvh->pv_list, pv, pv_list);
			break;
		}
	}
	return (pv);
}

static void
pmap_pv_demote_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa)
{
	struct md_page *pvh;
	pv_entry_t pv;
	vm_offset_t va_last;
	vm_page_t m;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	KASSERT((pa & PDRMASK) == 0,
	    ("pmap_pv_demote_pde: pa is not 4mpage aligned"));

	/*
	 * Transfer the 4mpage's pv entry for this mapping to the first
	 * page's pv list.
	 */
	pvh = pa_to_pvh(pa);
	va = trunc_4mpage(va);
	pv = pmap_pvh_remove(pvh, pmap, va);
	KASSERT(pv != NULL, ("pmap_pv_demote_pde: pv not found"));
	m = PHYS_TO_VM_PAGE(pa);
	TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
	/* Instantiate the remaining NPTEPG - 1 pv entries. */
	va_last = va + NBPDR - PAGE_SIZE;
	do {
		m++;
		KASSERT((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0,
		    ("pmap_pv_demote_pde: page %p is not managed", m));
		va += PAGE_SIZE;
		pmap_insert_entry(pmap, va, m);
	} while (va < va_last);
}

static void
pmap_pv_promote_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa)
{
	struct md_page *pvh;
	pv_entry_t pv;
	vm_offset_t va_last;
	vm_page_t m;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	KASSERT((pa & PDRMASK) == 0,
	    ("pmap_pv_promote_pde: pa is not 4mpage aligned"));

	/*
	 * Transfer the first page's pv entry for this mapping to the
	 * 4mpage's pv list.  Aside from avoiding the cost of a call
	 * to get_pv_entry(), a transfer avoids the possibility that
	 * get_pv_entry() calls pmap_collect() and that pmap_collect()
	 * removes one of the mappings that is being promoted.
	 */
	m = PHYS_TO_VM_PAGE(pa);
	va = trunc_4mpage(va);
	pv = pmap_pvh_remove(&m->md, pmap, va);
	KASSERT(pv != NULL, ("pmap_pv_promote_pde: pv not found"));
	pvh = pa_to_pvh(pa);
	TAILQ_INSERT_TAIL(&pvh->pv_list, pv, pv_list);
	/* Free the remaining NPTEPG - 1 pv entries. */
	va_last = va + NBPDR - PAGE_SIZE;
	do {
		m++;
		va += PAGE_SIZE;
		pmap_pvh_free(&m->md, pmap, va);
	} while (va < va_last);
}

static void
pmap_pvh_free(struct md_page *pvh, pmap_t pmap, vm_offset_t va)
{
	pv_entry_t pv;

	pv = pmap_pvh_remove(pvh, pmap, va);
	KASSERT(pv != NULL, ("pmap_pvh_free: pv not found"));
	free_pv_entry(pmap, pv);
}

static void
pmap_remove_entry(pmap_t pmap, vm_page_t m, vm_offset_t va)
{
	struct md_page *pvh;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	pmap_pvh_free(&m->md, pmap, va);
	if (TAILQ_EMPTY(&m->md.pv_list)) {
		pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
		if (TAILQ_EMPTY(&pvh->pv_list))
			vm_page_flag_clear(m, PG_WRITEABLE);
	}
}

/*
 * Create a pv entry for page at pa for
 * (pmap, va).
 */
static void
pmap_insert_entry(pmap_t pmap, vm_offset_t va, vm_page_t m)
{
	pv_entry_t pv;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	pv = get_pv_entry(pmap, FALSE);
	pv->pv_va = va;
	TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
}

/*
 * Conditionally create a pv entry.
 */
static boolean_t
pmap_try_insert_pv_entry(pmap_t pmap, vm_offset_t va, vm_page_t m)
{
	pv_entry_t pv;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	if (pv_entry_count < pv_entry_high_water &&
	    (pv = get_pv_entry(pmap, TRUE)) != NULL) {
		pv->pv_va = va;
		TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
		return (TRUE);
	} else
		return (FALSE);
}

/*
 * Create the pv entries for each of the pages within a superpage.
 */
static boolean_t
pmap_pv_insert_pde(pmap_t pmap, vm_offset_t va, vm_paddr_t pa)
{
	struct md_page *pvh;
	pv_entry_t pv;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	if (pv_entry_count < pv_entry_high_water &&
	    (pv = get_pv_entry(pmap, TRUE)) != NULL) {
		pv->pv_va = va;
		pvh = pa_to_pvh(pa);
		TAILQ_INSERT_TAIL(&pvh->pv_list, pv, pv_list);
		return (TRUE);
	} else
		return (FALSE);
}

/*
 * Tries to demote a 2- or 4MB page mapping.
 */
static boolean_t
pmap_demote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
{
	pd_entry_t newpde, oldpde;
	pmap_t allpmaps_entry;
	pt_entry_t *firstpte, newpte, *pte;
	vm_paddr_t mptepa;
	vm_page_t free, mpte;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	mpte = pmap_lookup_pt_page(pmap, va);
	if (mpte != NULL)
		pmap_remove_pt_page(pmap, mpte);
	else {
		KASSERT((*pde & PG_W) == 0,
		    ("pmap_demote_pde: page table page for a wired mapping"
		    " is missing"));
		free = NULL;
		pmap_remove_pde(pmap, pde, trunc_4mpage(va), &free);
		pmap_invalidate_page(pmap, trunc_4mpage(va));
		pmap_free_zero_pages(free);
		CTR2(KTR_PMAP, "pmap_demote_pde: failure for va %#x"
		    " in pmap %p", va, pmap);
		return (FALSE);
	}
	mptepa = VM_PAGE_TO_PHYS(mpte);

	/*
	 * Temporarily map the page table page (mpte) into the kernel's
	 * address space at either PADDR1 or PADDR2.
	 */
	if (curthread->td_pinned > 0 && mtx_owned(&vm_page_queue_mtx)) {
		if ((*PMAP1 & PG_FRAME) != mptepa) {
			*PMAP1 = mptepa | PG_RW | PG_V | PG_A | PG_M;
#ifdef SMP
			PMAP1cpu = PCPU_GET(cpuid);
#endif
			invlcaddr(PADDR1);
			PMAP1changed++;
		} else
#ifdef SMP
		if (PMAP1cpu != PCPU_GET(cpuid)) {
			PMAP1cpu = PCPU_GET(cpuid);
			invlcaddr(PADDR1);
			PMAP1changedcpu++;
		} else
#endif
			PMAP1unchanged++;
		firstpte = PADDR1;
	} else {
		mtx_lock(&PMAP2mutex);
		if ((*PMAP2 & PG_FRAME) != mptepa) {
			*PMAP2 = mptepa | PG_RW | PG_V | PG_A | PG_M;
			pmap_invalidate_page(kernel_pmap, (vm_offset_t)PADDR2);
		}
		firstpte = PADDR2;
	}
	oldpde = *pde;
	newpde = mptepa | PG_M | PG_A | (oldpde & PG_U) | PG_RW | PG_V;
	KASSERT((oldpde & (PG_A | PG_V)) == (PG_A | PG_V),
	    ("pmap_demote_pde: oldpde is missing PG_A and/or PG_V"));
	KASSERT((oldpde & (PG_M | PG_RW)) != PG_RW,
	    ("pmap_demote_pde: oldpde is missing PG_M"));
	KASSERT((oldpde & PG_PS) != 0,
	    ("pmap_demote_pde: oldpde is missing PG_PS"));
	newpte = oldpde & ~PG_PS;
	if ((newpte & PG_PDE_PAT) != 0)
		newpte ^= PG_PDE_PAT | PG_PTE_PAT;

	/*
	 * If the mapping has changed attributes, update the page table
	 * entries.
	 */
	KASSERT((*firstpte & PG_FRAME) == (newpte & PG_FRAME),
	    ("pmap_demote_pde: firstpte and newpte map different physical"
	    " addresses"));
	if ((*firstpte & PG_PTE_PROMOTE) != (newpte & PG_PTE_PROMOTE))
		for (pte = firstpte; pte < firstpte + NPTEPG; pte++) {
			*pte = newpte;
			newpte += PAGE_SIZE;
		}

	/*
	 * Demote the mapping.  This pmap is locked.  The old PDE has
	 * PG_A set.  If the old PDE has PG_RW set, it also has PG_M
	 * set.  Thus, there is no danger of a race with another
	 * processor changing the setting of PG_A and/or PG_M between
	 * the read above and the store below.
	 */
	if (pmap == kernel_pmap) {
		/*
		 * A harmless race exists between this loop and the bcopy()
		 * in pmap_pinit() that initializes the kernel segment of
		 * the new page table.  Specifically, that bcopy() may copy
		 * the new PDE from the PTD, which is first in allpmaps, to
		 * the new page table before this loop updates that new
		 * page table.
		 */
		mtx_lock_spin(&allpmaps_lock);
		LIST_FOREACH(allpmaps_entry, &allpmaps, pm_list) {
			pde = pmap_pde(allpmaps_entry, va);
			KASSERT(*pde == newpde || (*pde & PG_PTE_PROMOTE) ==
			    (oldpde & PG_PTE_PROMOTE),
			    ("pmap_demote_pde: pde was %#jx, expected %#jx",
			    (uintmax_t)*pde, (uintmax_t)oldpde));
			pde_store(pde, newpde);
		}
		mtx_unlock_spin(&allpmaps_lock);
	} else
		pde_store(pde, newpde);
	if (firstpte == PADDR2)
		mtx_unlock(&PMAP2mutex);

	/*
	 * Invalidate the recursive mapping of the page table page.
	 */
	pmap_invalidate_page(pmap, (vm_offset_t)vtopte(va));

	/*
	 * Demote the pv entry.  This depends on the earlier demotion
	 * of the mapping.  Specifically, the (re)creation of a per-
	 * page pv entry might trigger the execution of pmap_collect(),
	 * which might reclaim a newly (re)created per-page pv entry
	 * and destroy the associated mapping.  In order to destroy
	 * the mapping, the PDE must have already changed from mapping
	 * the 2mpage to referencing the page table page.
	 */
	if ((oldpde & PG_MANAGED) != 0)
		pmap_pv_demote_pde(pmap, va, oldpde & PG_PS_FRAME);

	pmap_pde_demotions++;
	CTR2(KTR_PMAP, "pmap_demote_pde: success for va %#x"
	    " in pmap %p", va, pmap);
	return (TRUE);
}

/*
 * pmap_remove_pde: do the things to unmap a superpage in a process
 */
static void
pmap_remove_pde(pmap_t pmap, pd_entry_t *pdq, vm_offset_t sva,
    vm_page_t *free)
{
	struct md_page *pvh;
	pd_entry_t oldpde;
	vm_offset_t eva, va;
	vm_page_t m, mpte;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	KASSERT((sva & PDRMASK) == 0,
	    ("pmap_remove_pde: sva is not 4mpage aligned"));
	oldpde = pte_load_clear(pdq);
	if (oldpde & PG_W)
		pmap->pm_stats.wired_count -= NBPDR / PAGE_SIZE;

	/*
	 * Machines that don't support invlpg, also don't support
	 * PG_G.
	 */
	if (oldpde & PG_G)
		pmap_invalidate_page(kernel_pmap, sva);
	pmap->pm_stats.resident_count -= NBPDR / PAGE_SIZE;
	if (oldpde & PG_MANAGED) {
		pvh = pa_to_pvh(oldpde & PG_PS_FRAME);
		pmap_pvh_free(pvh, pmap, sva);
		eva = sva + NBPDR;
		for (va = sva, m = PHYS_TO_VM_PAGE(oldpde & PG_PS_FRAME);
		    va < eva; va += PAGE_SIZE, m++) {
			if ((oldpde & (PG_M | PG_RW)) == (PG_M | PG_RW))
				vm_page_dirty(m);
			if (oldpde & PG_A)
				vm_page_flag_set(m, PG_REFERENCED);
			if (TAILQ_EMPTY(&m->md.pv_list) &&
			    TAILQ_EMPTY(&pvh->pv_list))
				vm_page_flag_clear(m, PG_WRITEABLE);
		}
	}
	if (pmap == kernel_pmap) {
		if (!pmap_demote_pde(pmap, pdq, sva))
			panic("pmap_remove_pde: failed demotion");
	} else {
		mpte = pmap_lookup_pt_page(pmap, sva);
		if (mpte != NULL) {
			pmap_remove_pt_page(pmap, mpte);
			pmap->pm_stats.resident_count--;
			KASSERT(mpte->wire_count == NPTEPG,
			    ("pmap_remove_pde: pte page wire count error"));
			mpte->wire_count = 0;
			pmap_add_delayed_free_list(mpte, free, FALSE);
			atomic_subtract_int(&cnt.v_wire_count, 1);
		}
	}
}

/*
 * pmap_remove_pte: do the things to unmap a page in a process
 */
static int
pmap_remove_pte(pmap_t pmap, pt_entry_t *ptq, vm_offset_t va, vm_page_t *free)
{
	pt_entry_t oldpte;
	vm_page_t m;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	oldpte = pte_load_clear(ptq);
	if (oldpte & PG_W)
		pmap->pm_stats.wired_count -= 1;
	/*
	 * Machines that don't support invlpg, also don't support
	 * PG_G.
	 */
	if (oldpte & PG_G)
		pmap_invalidate_page(kernel_pmap, va);
	pmap->pm_stats.resident_count -= 1;
	if (oldpte & PG_MANAGED) {
		m = PHYS_TO_VM_PAGE(oldpte & PG_FRAME);
		if ((oldpte & (PG_M | PG_RW)) == (PG_M | PG_RW))
			vm_page_dirty(m);
		if (oldpte & PG_A)
			vm_page_flag_set(m, PG_REFERENCED);
		pmap_remove_entry(pmap, m, va);
	}
	return (pmap_unuse_pt(pmap, va, free));
}

/*
 * Remove a single page from a process address space
 */
static void
pmap_remove_page(pmap_t pmap, vm_offset_t va, vm_page_t *free)
{
	pt_entry_t *pte;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	KASSERT(curthread->td_pinned > 0, ("curthread not pinned"));
	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	if ((pte = pmap_pte_quick(pmap, va)) == NULL || *pte == 0)
		return;
	pmap_remove_pte(pmap, pte, va, free);
	pmap_invalidate_page(pmap, va);
}

/*
 *	Remove the given range of addresses from the specified map.
 *
 *	It is assumed that the start and end are properly
 *	rounded to the page size.
 */
void
pmap_remove(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
{
	vm_offset_t pdnxt;
	pd_entry_t ptpaddr;
	pt_entry_t *pte;
	vm_page_t free = NULL;
	int anyvalid;

	/*
	 * Perform an unsynchronized read.  This is, however, safe.
	 */
	if (pmap->pm_stats.resident_count == 0)
		return;

	anyvalid = 0;

	vm_page_lock_queues();
	sched_pin();
	PMAP_LOCK(pmap);

	/*
	 * special handling of removing one page.  a very
	 * common operation and easy to short circuit some
	 * code.
	 */
	if ((sva + PAGE_SIZE == eva) &&
	    ((pmap->pm_pdir[(sva >> PDRSHIFT)] & PG_PS) == 0)) {
		pmap_remove_page(pmap, sva, &free);
		goto out;
	}

	for (; sva < eva; sva = pdnxt) {
		unsigned pdirindex;

		/*
		 * Calculate index for next page table.
		 */
		pdnxt = (sva + NBPDR) & ~PDRMASK;
		if (pdnxt < sva)
			pdnxt = eva;
		if (pmap->pm_stats.resident_count == 0)
			break;

		pdirindex = sva >> PDRSHIFT;
		ptpaddr = pmap->pm_pdir[pdirindex];

		/*
		 * Weed out invalid mappings. Note: we assume that the page
		 * directory table is always allocated, and in kernel virtual.
		 */
		if (ptpaddr == 0)
			continue;

		/*
		 * Check for large page.
		 */
		if ((ptpaddr & PG_PS) != 0) {
			/*
			 * Are we removing the entire large page?  If not,
			 * demote the mapping and fall through.
			 */
			if (sva + NBPDR == pdnxt && eva >= pdnxt) {
				/*
				 * The TLB entry for a PG_G mapping is
				 * invalidated by pmap_remove_pde().
				 */
				if ((ptpaddr & PG_G) == 0)
					anyvalid = 1;
				pmap_remove_pde(pmap,
				    &pmap->pm_pdir[pdirindex], sva, &free);
				continue;
			} else if (!pmap_demote_pde(pmap,
			    &pmap->pm_pdir[pdirindex], sva)) {
				/* The large page mapping was destroyed. */
				continue;
			}
		}

		/*
		 * Limit our scan to either the end of the va represented
		 * by the current page table page, or to the end of the
		 * range being removed.
		 */
		if (pdnxt > eva)
			pdnxt = eva;

		for (pte = pmap_pte_quick(pmap, sva); sva != pdnxt; pte++,
		    sva += PAGE_SIZE) {
			if (*pte == 0)
				continue;

			/*
			 * The TLB entry for a PG_G mapping is invalidated
			 * by pmap_remove_pte().
			 */
			if ((*pte & PG_G) == 0)
				anyvalid = 1;
			if (pmap_remove_pte(pmap, pte, sva, &free))
				break;
		}
	}
out:
	sched_unpin();
	if (anyvalid)
		pmap_invalidate_all(pmap);
	vm_page_unlock_queues();
	PMAP_UNLOCK(pmap);
	pmap_free_zero_pages(free);
}

/*
 *	Routine:	pmap_remove_all
 *	Function:
 *		Removes this physical page from
 *		all physical maps in which it resides.
 *		Reflects back modify bits to the pager.
 *
 *	Notes:
 *		Original versions of this routine were very
 *		inefficient because they iteratively called
 *		pmap_remove (slow...)
 */

void
pmap_remove_all(vm_page_t m)
{
	struct md_page *pvh;
	pv_entry_t pv;
	pmap_t pmap;
	pt_entry_t *pte, tpte;
	pd_entry_t *pde;
	vm_offset_t va;
	vm_page_t free;

	KASSERT((m->flags & PG_FICTITIOUS) == 0,
	    ("pmap_remove_all: page %p is fictitious", m));
	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	sched_pin();
	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
	while ((pv = TAILQ_FIRST(&pvh->pv_list)) != NULL) {
		va = pv->pv_va;
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, va);
		(void)pmap_demote_pde(pmap, pde, va);
		PMAP_UNLOCK(pmap);
	}
	while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pmap->pm_stats.resident_count--;
		pde = pmap_pde(pmap, pv->pv_va);
		KASSERT((*pde & PG_PS) == 0, ("pmap_remove_all: found"
		    " a 4mpage in page %p's pv list", m));
		pte = pmap_pte_quick(pmap, pv->pv_va);
		tpte = pte_load_clear(pte);
		if (tpte & PG_W)
			pmap->pm_stats.wired_count--;
		if (tpte & PG_A)
			vm_page_flag_set(m, PG_REFERENCED);

		/*
		 * Update the vm_page_t clean and reference bits.
		 */
		if ((tpte & (PG_M | PG_RW)) == (PG_M | PG_RW))
			vm_page_dirty(m);
		free = NULL;
		pmap_unuse_pt(pmap, pv->pv_va, &free);
		pmap_invalidate_page(pmap, pv->pv_va);
		pmap_free_zero_pages(free);
		TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
		free_pv_entry(pmap, pv);
		PMAP_UNLOCK(pmap);
	}
	vm_page_flag_clear(m, PG_WRITEABLE);
	sched_unpin();
}

/*
 * pmap_protect_pde: do the things to protect a 4mpage in a process
 */
static boolean_t
pmap_protect_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t sva, vm_prot_t prot)
{
	pd_entry_t newpde, oldpde;
	vm_offset_t eva, va;
	vm_page_t m;
	boolean_t anychanged;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	KASSERT((sva & PDRMASK) == 0,
	    ("pmap_protect_pde: sva is not 4mpage aligned"));
	anychanged = FALSE;
retry:
	oldpde = newpde = *pde;
	if (oldpde & PG_MANAGED) {
		eva = sva + NBPDR;
		for (va = sva, m = PHYS_TO_VM_PAGE(oldpde & PG_PS_FRAME);
		    va < eva; va += PAGE_SIZE, m++) {
			/*
			 * In contrast to the analogous operation on a 4KB page
			 * mapping, the mapping's PG_A flag is not cleared and
			 * the page's PG_REFERENCED flag is not set.  The
			 * reason is that pmap_demote_pde() expects that a 2/4MB
			 * page mapping with a stored page table page has PG_A
			 * set.
			 */
			if ((oldpde & (PG_M | PG_RW)) == (PG_M | PG_RW))
				vm_page_dirty(m);
		}
	}
	if ((prot & VM_PROT_WRITE) == 0)
		newpde &= ~(PG_RW | PG_M);
#ifdef PAE
	if ((prot & VM_PROT_EXECUTE) == 0)
		newpde |= pg_nx;
#endif
	if (newpde != oldpde) {
		if (!pde_cmpset(pde, oldpde, newpde))
			goto retry;
		if (oldpde & PG_G)
			pmap_invalidate_page(pmap, sva);
		else
			anychanged = TRUE;
	}
	return (anychanged);
}

/*
 *	Set the physical protection on the
 *	specified range of this map as requested.
 */
void
pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
{
	vm_offset_t pdnxt;
	pd_entry_t ptpaddr;
	pt_entry_t *pte;
	int anychanged;

	if ((prot & VM_PROT_READ) == VM_PROT_NONE) {
		pmap_remove(pmap, sva, eva);
		return;
	}

#ifdef PAE
	if ((prot & (VM_PROT_WRITE|VM_PROT_EXECUTE)) ==
	    (VM_PROT_WRITE|VM_PROT_EXECUTE))
		return;
#else
	if (prot & VM_PROT_WRITE)
		return;
#endif

	anychanged = 0;

	vm_page_lock_queues();
	sched_pin();
	PMAP_LOCK(pmap);
	for (; sva < eva; sva = pdnxt) {
		pt_entry_t obits, pbits;
		unsigned pdirindex;

		pdnxt = (sva + NBPDR) & ~PDRMASK;
		if (pdnxt < sva)
			pdnxt = eva;

		pdirindex = sva >> PDRSHIFT;
		ptpaddr = pmap->pm_pdir[pdirindex];

		/*
		 * Weed out invalid mappings. Note: we assume that the page
		 * directory table is always allocated, and in kernel virtual.
		 */
		if (ptpaddr == 0)
			continue;

		/*
		 * Check for large page.
		 */
		if ((ptpaddr & PG_PS) != 0) {
			/*
			 * Are we protecting the entire large page?  If not,
			 * demote the mapping and fall through.
			 */
			if (sva + NBPDR == pdnxt && eva >= pdnxt) {
				/*
				 * The TLB entry for a PG_G mapping is
				 * invalidated by pmap_protect_pde().
				 */
				if (pmap_protect_pde(pmap,
				    &pmap->pm_pdir[pdirindex], sva, prot))
					anychanged = 1;
				continue;
			} else if (!pmap_demote_pde(pmap,
			    &pmap->pm_pdir[pdirindex], sva)) {
				/* The large page mapping was destroyed. */
				continue;
			}
		}

		if (pdnxt > eva)
			pdnxt = eva;

		for (pte = pmap_pte_quick(pmap, sva); sva != pdnxt; pte++,
		    sva += PAGE_SIZE) {
			vm_page_t m;

retry:
			/*
			 * Regardless of whether a pte is 32 or 64 bits in
			 * size, PG_RW, PG_A, and PG_M are among the least
			 * significant 32 bits.
			 */
			obits = pbits = *pte;
			if ((pbits & PG_V) == 0)
				continue;
			if (pbits & PG_MANAGED) {
				m = NULL;
				if (pbits & PG_A) {
					m = PHYS_TO_VM_PAGE(pbits & PG_FRAME);
					vm_page_flag_set(m, PG_REFERENCED);
					pbits &= ~PG_A;
				}
				if ((pbits & (PG_M | PG_RW)) == (PG_M | PG_RW)) {
					if (m == NULL)
						m = PHYS_TO_VM_PAGE(pbits & PG_FRAME);
					vm_page_dirty(m);
				}
			}

			if ((prot & VM_PROT_WRITE) == 0)
				pbits &= ~(PG_RW | PG_M);
#ifdef PAE
			if ((prot & VM_PROT_EXECUTE) == 0)
				pbits |= pg_nx;
#endif

			if (pbits != obits) {
#ifdef PAE
				if (!atomic_cmpset_64(pte, obits, pbits))
					goto retry;
#else
				if (!atomic_cmpset_int((u_int *)pte, obits,
				    pbits))
					goto retry;
#endif
				if (obits & PG_G)
					pmap_invalidate_page(pmap, sva);
				else
					anychanged = 1;
			}
		}
	}
	sched_unpin();
	if (anychanged)
		pmap_invalidate_all(pmap);
	vm_page_unlock_queues();
	PMAP_UNLOCK(pmap);
}

/*
 * Tries to promote the 512 or 1024, contiguous 4KB page mappings that are
 * within a single page table page (PTP) to a single 2- or 4MB page mapping.
 * For promotion to occur, two conditions must be met: (1) the 4KB page
 * mappings must map aligned, contiguous physical memory and (2) the 4KB page
 * mappings must have identical characteristics.
 *
 * Managed (PG_MANAGED) mappings within the kernel address space are not
 * promoted.  The reason is that kernel PDEs are replicated in each pmap but
 * pmap_clear_ptes() and pmap_ts_referenced() only read the PDE from the kernel
 * pmap.
 */
static void
pmap_promote_pde(pmap_t pmap, pd_entry_t *pde, vm_offset_t va)
{
	pd_entry_t newpde;
	pmap_t allpmaps_entry;
	pt_entry_t *firstpte, oldpte, pa, *pte;
	vm_offset_t oldpteva;
	vm_page_t mpte;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);

	/*
	 * Examine the first PTE in the specified PTP.  Abort if this PTE is
	 * either invalid, unused, or does not map the first 4KB physical page
	 * within a 2- or 4MB page.
	 */
	firstpte = vtopte(trunc_4mpage(va));
setpde:
	newpde = *firstpte;
	if ((newpde & ((PG_FRAME & PDRMASK) | PG_A | PG_V)) != (PG_A | PG_V)) {
		pmap_pde_p_failures++;
		CTR2(KTR_PMAP, "pmap_promote_pde: failure for va %#x"
		    " in pmap %p", va, pmap);
		return;
	}
	if ((*firstpte & PG_MANAGED) != 0 && pmap == kernel_pmap) {
		pmap_pde_p_failures++;
		CTR2(KTR_PMAP, "pmap_promote_pde: failure for va %#x"
		    " in pmap %p", va, pmap);
		return;
	}
	if ((newpde & (PG_M | PG_RW)) == PG_RW) {
		/*
		 * When PG_M is already clear, PG_RW can be cleared without
		 * a TLB invalidation.
		 */
		if (!atomic_cmpset_int((u_int *)firstpte, newpde, newpde &
		    ~PG_RW))
			goto setpde;
		newpde &= ~PG_RW;
	}

	/*
	 * Examine each of the other PTEs in the specified PTP.  Abort if this
	 * PTE maps an unexpected 4KB physical page or does not have identical
	 * characteristics to the first PTE.
	 */
	pa = (newpde & (PG_PS_FRAME | PG_A | PG_V)) + NBPDR - PAGE_SIZE;
	for (pte = firstpte + NPTEPG - 1; pte > firstpte; pte--) {
setpte:
		oldpte = *pte;
		if ((oldpte & (PG_FRAME | PG_A | PG_V)) != pa) {
			pmap_pde_p_failures++;
			CTR2(KTR_PMAP, "pmap_promote_pde: failure for va %#x"
			    " in pmap %p", va, pmap);
			return;
		}
		if ((oldpte & (PG_M | PG_RW)) == PG_RW) {
			/*
			 * When PG_M is already clear, PG_RW can be cleared
			 * without a TLB invalidation.
			 */
			if (!atomic_cmpset_int((u_int *)pte, oldpte,
			    oldpte & ~PG_RW))
				goto setpte;
			oldpte &= ~PG_RW;
			oldpteva = (oldpte & PG_FRAME & PDRMASK) |
			    (va & ~PDRMASK);
			CTR2(KTR_PMAP, "pmap_promote_pde: protect for va %#x"
			    " in pmap %p", oldpteva, pmap);
		}
		if ((oldpte & PG_PTE_PROMOTE) != (newpde & PG_PTE_PROMOTE)) {
			pmap_pde_p_failures++;
			CTR2(KTR_PMAP, "pmap_promote_pde: failure for va %#x"
			    " in pmap %p", va, pmap);
			return;
		}
		pa -= PAGE_SIZE;
	}

	/*
	 * Save the page table page in its current state until the PDE
	 * mapping the superpage is demoted by pmap_demote_pde() or
	 * destroyed by pmap_remove_pde().
	 */
	mpte = PHYS_TO_VM_PAGE(*pde & PG_FRAME);
	KASSERT(mpte >= vm_page_array &&
	    mpte < &vm_page_array[vm_page_array_size],
	    ("pmap_promote_pde: page table page is out of range"));
	KASSERT(mpte->pindex == va >> PDRSHIFT,
	    ("pmap_promote_pde: page table page's pindex is wrong"));
	pmap_insert_pt_page(pmap, mpte);

	/*
	 * Promote the pv entries.
	 */
	if ((newpde & PG_MANAGED) != 0)
		pmap_pv_promote_pde(pmap, va, newpde & PG_PS_FRAME);

	/*
	 * Propagate the PAT index to its proper position.
	 */
	if ((newpde & PG_PTE_PAT) != 0)
		newpde ^= PG_PDE_PAT | PG_PTE_PAT;

	/*
	 * Map the superpage.
	 */
	if (pmap == kernel_pmap) {
		mtx_lock_spin(&allpmaps_lock);
		LIST_FOREACH(allpmaps_entry, &allpmaps, pm_list) {
			pde = pmap_pde(allpmaps_entry, va);
			pde_store(pde, PG_PS | newpde);
		}
		mtx_unlock_spin(&allpmaps_lock);
	} else
		pde_store(pde, PG_PS | newpde);

	pmap_pde_promotions++;
	CTR2(KTR_PMAP, "pmap_promote_pde: success for va %#x"
	    " in pmap %p", va, pmap);
}

/*
 *	Insert the given physical page (p) at
 *	the specified virtual address (v) in the
 *	target physical map with the protection requested.
 *
 *	If specified, the page will be wired down, meaning
 *	that the related pte can not be reclaimed.
 *
 *	NB:  This is the only routine which MAY NOT lazy-evaluate
 *	or lose information.  That is, this routine must actually
 *	insert this page into the given map NOW.
 */
void
pmap_enter(pmap_t pmap, vm_offset_t va, vm_prot_t access, vm_page_t m,
    vm_prot_t prot, boolean_t wired)
{
	vm_paddr_t pa;
	pd_entry_t *pde;
	pt_entry_t *pte;
	vm_paddr_t opa;
	pt_entry_t origpte, newpte;
	vm_page_t mpte, om;
	boolean_t invlva;

	va = trunc_page(va);
	KASSERT(va <= VM_MAX_KERNEL_ADDRESS, ("pmap_enter: toobig"));
	KASSERT(va < UPT_MIN_ADDRESS || va >= UPT_MAX_ADDRESS,
	    ("pmap_enter: invalid to pmap_enter page table pages (va: 0x%x)", va));

	mpte = NULL;

	vm_page_lock_queues();
	PMAP_LOCK(pmap);
	sched_pin();

	/*
	 * In the case that a page table page is not
	 * resident, we are creating it here.
	 */
	if (va < VM_MAXUSER_ADDRESS) {
		mpte = pmap_allocpte(pmap, va, M_WAITOK);
	}

	pde = pmap_pde(pmap, va);
	if ((*pde & PG_PS) != 0)
		panic("pmap_enter: attempted pmap_enter on 4MB page");
	pte = pmap_pte_quick(pmap, va);

	/*
	 * Page Directory table entry not valid, we need a new PT page
	 */
	if (pte == NULL) {
		panic("pmap_enter: invalid page directory pdir=%#jx, va=%#x",
			(uintmax_t)pmap->pm_pdir[PTDPTDI], va);
	}

	pa = VM_PAGE_TO_PHYS(m);
	om = NULL;
	origpte = *pte;
	opa = origpte & PG_FRAME;

	/*
	 * Mapping has not changed, must be protection or wiring change.
	 */
	if (origpte && (opa == pa)) {
		/*
		 * Wiring change, just update stats. We don't worry about
		 * wiring PT pages as they remain resident as long as there
		 * are valid mappings in them. Hence, if a user page is wired,
		 * the PT page will be also.
		 */
		if (wired && ((origpte & PG_W) == 0))
			pmap->pm_stats.wired_count++;
		else if (!wired && (origpte & PG_W))
			pmap->pm_stats.wired_count--;

		/*
		 * Remove extra pte reference
		 */
		if (mpte)
			mpte->wire_count--;

		/*
		 * We might be turning off write access to the page,
		 * so we go ahead and sense modify status.
		 */
		if (origpte & PG_MANAGED) {
			om = m;
			pa |= PG_MANAGED;
		}
		goto validate;
	}
	/*
	 * Mapping has changed, invalidate old range and fall through to
	 * handle validating new mapping.
	 */
	if (opa) {
		if (origpte & PG_W)
			pmap->pm_stats.wired_count--;
		if (origpte & PG_MANAGED) {
			om = PHYS_TO_VM_PAGE(opa);
			pmap_remove_entry(pmap, om, va);
		}
		if (mpte != NULL) {
			mpte->wire_count--;
			KASSERT(mpte->wire_count > 0,
			    ("pmap_enter: missing reference to page table page,"
			     " va: 0x%x", va));
		}
	} else
		pmap->pm_stats.resident_count++;

	/*
	 * Enter on the PV list if part of our managed memory.
	 */
	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0) {
		KASSERT(va < kmi.clean_sva || va >= kmi.clean_eva,
		    ("pmap_enter: managed mapping within the clean submap"));
		pmap_insert_entry(pmap, va, m);
		pa |= PG_MANAGED;
	}

	/*
	 * Increment counters
	 */
	if (wired)
		pmap->pm_stats.wired_count++;

validate:
	/*
	 * Now validate mapping with desired protection/wiring.
	 */
	newpte = (pt_entry_t)(pa | PG_V);
	if ((prot & VM_PROT_WRITE) != 0) {
		newpte |= PG_RW;
		vm_page_flag_set(m, PG_WRITEABLE);
	}
#ifdef PAE
	if ((prot & VM_PROT_EXECUTE) == 0)
		newpte |= pg_nx;
#endif
	if (wired)
		newpte |= PG_W;
	if (va < VM_MAXUSER_ADDRESS)
		newpte |= PG_U;
	if (pmap == kernel_pmap)
		newpte |= pgeflag;

	/*
	 * if the mapping or permission bits are different, we need
	 * to update the pte.
	 */
	if ((origpte & ~(PG_M|PG_A)) != newpte) {
		newpte |= PG_A;
		if ((access & VM_PROT_WRITE) != 0)
			newpte |= PG_M;
		if (origpte & PG_V) {
			invlva = FALSE;
			origpte = pte_load_store(pte, newpte);
			if (origpte & PG_A) {
				if (origpte & PG_MANAGED)
					vm_page_flag_set(om, PG_REFERENCED);
				if (opa != VM_PAGE_TO_PHYS(m))
					invlva = TRUE;
#ifdef PAE
				if ((origpte & PG_NX) == 0 &&
				    (newpte & PG_NX) != 0)
					invlva = TRUE;
#endif
			}
			if ((origpte & (PG_M | PG_RW)) == (PG_M | PG_RW)) {
				if ((origpte & PG_MANAGED) != 0)
					vm_page_dirty(om);
				if ((prot & VM_PROT_WRITE) == 0)
					invlva = TRUE;
			}
			if (invlva)
				pmap_invalidate_page(pmap, va);
		} else
			pte_store(pte, newpte);
	}

	/*
	 * If both the page table page and the reservation are fully
	 * populated, then attempt promotion.
	 */
	if ((mpte == NULL || mpte->wire_count == NPTEPG) &&
	    pg_ps_enabled && vm_reserv_level_iffullpop(m) == 0)
		pmap_promote_pde(pmap, pde, va);

	sched_unpin();
	vm_page_unlock_queues();
	PMAP_UNLOCK(pmap);
}

/*
 * Tries to create a 2- or 4MB page mapping.  Returns TRUE if successful and
 * FALSE otherwise.  Fails if (1) a page table page cannot be allocated without
 * blocking, (2) a mapping already exists at the specified virtual address, or
 * (3) a pv entry cannot be allocated without reclaiming another pv entry.
 */
static boolean_t
pmap_enter_pde(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot)
{
	pd_entry_t *pde, newpde;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	PMAP_LOCK_ASSERT(pmap, MA_OWNED);
	pde = pmap_pde(pmap, va);
	if (*pde != 0) {
		CTR2(KTR_PMAP, "pmap_enter_pde: failure for va %#lx"
		    " in pmap %p", va, pmap);
		return (FALSE);
	}
	newpde = VM_PAGE_TO_PHYS(m) | PG_PS | PG_V;
	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0) {
		newpde |= PG_MANAGED;

		/*
		 * Abort this mapping if its PV entry could not be created.
		 */
		if (!pmap_pv_insert_pde(pmap, va, VM_PAGE_TO_PHYS(m))) {
			CTR2(KTR_PMAP, "pmap_enter_pde: failure for va %#lx"
			    " in pmap %p", va, pmap);
			return (FALSE);
		}
	}
#ifdef PAE
	if ((prot & VM_PROT_EXECUTE) == 0)
		newpde |= pg_nx;
#endif
	if (va < VM_MAXUSER_ADDRESS)
		newpde |= PG_U;

	/*
	 * Increment counters.
	 */
	pmap->pm_stats.resident_count += NBPDR / PAGE_SIZE;

	/*
	 * Map the superpage.
	 */
	pde_store(pde, newpde);

	pmap_pde_mappings++;
	CTR2(KTR_PMAP, "pmap_enter_pde: success for va %#lx"
	    " in pmap %p", va, pmap);
	return (TRUE);
}

/*
 * Maps a sequence of resident pages belonging to the same object.
 * The sequence begins with the given page m_start.  This page is
 * mapped at the given virtual address start.  Each subsequent page is
 * mapped at a virtual address that is offset from start by the same
 * amount as the page is offset from m_start within the object.  The
 * last page in the sequence is the page with the largest offset from
 * m_start that can be mapped at a virtual address less than the given
 * virtual address end.  Not every virtual page between start and end
 * is mapped; only those for which a resident page exists with the
 * corresponding offset from m_start are mapped.
 */
void
pmap_enter_object(pmap_t pmap, vm_offset_t start, vm_offset_t end,
    vm_page_t m_start, vm_prot_t prot)
{
	vm_offset_t va;
	vm_page_t m, mpte;
	vm_pindex_t diff, psize;

	VM_OBJECT_LOCK_ASSERT(m_start->object, MA_OWNED);
	psize = atop(end - start);
	mpte = NULL;
	m = m_start;
	PMAP_LOCK(pmap);
	while (m != NULL && (diff = m->pindex - m_start->pindex) < psize) {
		va = start + ptoa(diff);
		if ((va & PDRMASK) == 0 && va + NBPDR <= end &&
		    (VM_PAGE_TO_PHYS(m) & PDRMASK) == 0 &&
		    pg_ps_enabled && vm_reserv_level_iffullpop(m) == 0 &&
		    pmap_enter_pde(pmap, va, m, prot))
			m = &m[NBPDR / PAGE_SIZE - 1];
		else
			mpte = pmap_enter_quick_locked(pmap, va, m, prot,
			    mpte);
		m = TAILQ_NEXT(m, listq);
	}
 	PMAP_UNLOCK(pmap);
}

/*
 * this code makes some *MAJOR* assumptions:
 * 1. Current pmap & pmap exists.
 * 2. Not wired.
 * 3. Read access.
 * 4. No page table pages.
 * but is *MUCH* faster than pmap_enter...
 */

void
pmap_enter_quick(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot)
{

	PMAP_LOCK(pmap);
	(void) pmap_enter_quick_locked(pmap, va, m, prot, NULL);
	PMAP_UNLOCK(pmap);
}

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)
{
	pt_entry_t *pte;
	vm_paddr_t pa;
	vm_page_t free;

	KASSERT(va < kmi.clean_sva || va >= kmi.clean_eva ||
	    (m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) != 0,
	    ("pmap_enter_quick_locked: managed mapping within the clean submap"));
	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	PMAP_LOCK_ASSERT(pmap, MA_OWNED);

	/*
	 * In the case that a page table page is not
	 * resident, we are creating it here.
	 */
	if (va < VM_MAXUSER_ADDRESS) {
		unsigned ptepindex;
		pd_entry_t ptepa;

		/*
		 * Calculate pagetable page index
		 */
		ptepindex = va >> PDRSHIFT;
		if (mpte && (mpte->pindex == ptepindex)) {
			mpte->wire_count++;
		} else {
			/*
			 * Get the page directory entry
			 */
			ptepa = pmap->pm_pdir[ptepindex];

			/*
			 * If the page table page is mapped, we just increment
			 * the hold count, and activate it.
			 */
			if (ptepa) {
				if (ptepa & PG_PS)
					return (NULL);
				mpte = PHYS_TO_VM_PAGE(ptepa & PG_FRAME);
				mpte->wire_count++;
			} else {
				mpte = _pmap_allocpte(pmap, ptepindex,
				    M_NOWAIT);
				if (mpte == NULL)
					return (mpte);
			}
		}
	} else {
		mpte = NULL;
	}

	/*
	 * This call to vtopte makes the assumption that we are
	 * entering the page into the current pmap.  In order to support
	 * quick entry into any pmap, one would likely use pmap_pte_quick.
	 * But that isn't as quick as vtopte.
	 */
	pte = vtopte(va);
	if (*pte) {
		if (mpte != NULL) {
			mpte->wire_count--;
			mpte = NULL;
		}
		return (mpte);
	}

	/*
	 * Enter on the PV list if part of our managed memory.
	 */
	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) == 0 &&
	    !pmap_try_insert_pv_entry(pmap, va, m)) {
		if (mpte != NULL) {
			free = NULL;
			if (pmap_unwire_pte_hold(pmap, mpte, &free)) {
				pmap_invalidate_page(pmap, va);
				pmap_free_zero_pages(free);
			}

			mpte = NULL;
		}
		return (mpte);
	}

	/*
	 * Increment counters
	 */
	pmap->pm_stats.resident_count++;

	pa = VM_PAGE_TO_PHYS(m);
#ifdef PAE
	if ((prot & VM_PROT_EXECUTE) == 0)
		pa |= pg_nx;
#endif

	/*
	 * Now validate mapping with RO protection
	 */
	if (m->flags & (PG_FICTITIOUS|PG_UNMANAGED))
		pte_store(pte, pa | PG_V | PG_U);
	else
		pte_store(pte, pa | PG_V | PG_U | PG_MANAGED);
	return mpte;
}

/*
 * Make a temporary mapping for a physical address.  This is only intended
 * to be used for panic dumps.
 */
void *
pmap_kenter_temporary(vm_paddr_t pa, int i)
{
	vm_offset_t va;

	va = (vm_offset_t)crashdumpmap + (i * PAGE_SIZE);
	pmap_kenter(va, pa);
	invlpg(va);
	return ((void *)crashdumpmap);
}

/*
 * This code maps large physical mmap regions into the
 * processor address space.  Note that some shortcuts
 * are taken, but the code works.
 */
void
pmap_object_init_pt(pmap_t pmap, vm_offset_t addr, vm_object_t object,
    vm_pindex_t pindex, vm_size_t size)
{
	pd_entry_t *pde;
	vm_paddr_t pa, ptepa;
	vm_page_t p;

	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
	KASSERT(object->type == OBJT_DEVICE,
	    ("pmap_object_init_pt: non-device object"));
	if (pseflag &&
	    (addr & (NBPDR - 1)) == 0 && (size & (NBPDR - 1)) == 0) {
		if (!vm_object_populate(object, pindex, pindex + atop(size)))
			return;
		p = vm_page_lookup(object, pindex);
		KASSERT(p->valid == VM_PAGE_BITS_ALL,
		    ("pmap_object_init_pt: invalid page %p", p));

		/*
		 * Abort the mapping if the first page is not physically
		 * aligned to a 2/4MB page boundary.
		 */
		ptepa = VM_PAGE_TO_PHYS(p);
		if (ptepa & (NBPDR - 1))
			return;

		/*
		 * Skip the first page.  Abort the mapping if the rest of
		 * the pages are not physically contiguous.
		 */
		p = TAILQ_NEXT(p, listq);
		for (pa = ptepa + PAGE_SIZE; pa < ptepa + size;
		    pa += PAGE_SIZE) {
			KASSERT(p->valid == VM_PAGE_BITS_ALL,
			    ("pmap_object_init_pt: invalid page %p", p));
			if (pa != VM_PAGE_TO_PHYS(p))
				return;
			p = TAILQ_NEXT(p, listq);
		}

		/* Map using 2/4MB pages. */
		PMAP_LOCK(pmap);
		for (pa = ptepa; pa < ptepa + size; pa += NBPDR) {
			pde = pmap_pde(pmap, addr);
			if (*pde == 0) {
				pde_store(pde, pa | PG_PS | PG_M | PG_A |
				    PG_U | PG_RW | PG_V);
				pmap->pm_stats.resident_count += NBPDR /
				    PAGE_SIZE;
				pmap_pde_mappings++;
			}
			/* Else continue on if the PDE is already valid. */
			addr += NBPDR;
		}
		PMAP_UNLOCK(pmap);
	}
}

/*
 *	Routine:	pmap_change_wiring
 *	Function:	Change the wiring attribute for a map/virtual-address
 *			pair.
 *	In/out conditions:
 *			The mapping must already exist in the pmap.
 */
void
pmap_change_wiring(pmap_t pmap, vm_offset_t va, boolean_t wired)
{
	pd_entry_t *pde;
	pt_entry_t *pte;
	boolean_t are_queues_locked;

	are_queues_locked = FALSE;
retry:
	PMAP_LOCK(pmap);
	pde = pmap_pde(pmap, va);
	if ((*pde & PG_PS) != 0) {
		if (!wired != ((*pde & PG_W) == 0)) {
			if (!are_queues_locked) {
				are_queues_locked = TRUE;
				if (!mtx_trylock(&vm_page_queue_mtx)) {
					PMAP_UNLOCK(pmap);
					vm_page_lock_queues();
					goto retry;
				}
			}
			if (!pmap_demote_pde(pmap, pde, va))
				panic("pmap_change_wiring: demotion failed");
		} else
			goto out;
	}
	pte = pmap_pte(pmap, va);

	if (wired && !pmap_pte_w(pte))
		pmap->pm_stats.wired_count++;
	else if (!wired && pmap_pte_w(pte))
		pmap->pm_stats.wired_count--;

	/*
	 * Wiring is not a hardware characteristic so there is no need to
	 * invalidate TLB.
	 */
	pmap_pte_set_w(pte, wired);
	pmap_pte_release(pte);
out:
	if (are_queues_locked)
		vm_page_unlock_queues();
	PMAP_UNLOCK(pmap);
}



/*
 *	Copy the range specified by src_addr/len
 *	from the source map to the range dst_addr/len
 *	in the destination map.
 *
 *	This routine is only advisory and need not do anything.
 */

void
pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr, vm_size_t len,
    vm_offset_t src_addr)
{
	vm_page_t   free;
	vm_offset_t addr;
	vm_offset_t end_addr = src_addr + len;
	vm_offset_t pdnxt;

	if (dst_addr != src_addr)
		return;

	if (!pmap_is_current(src_pmap))
		return;

	vm_page_lock_queues();
	if (dst_pmap < src_pmap) {
		PMAP_LOCK(dst_pmap);
		PMAP_LOCK(src_pmap);
	} else {
		PMAP_LOCK(src_pmap);
		PMAP_LOCK(dst_pmap);
	}
	sched_pin();
	for (addr = src_addr; addr < end_addr; addr = pdnxt) {
		pt_entry_t *src_pte, *dst_pte;
		vm_page_t dstmpte, srcmpte;
		pd_entry_t srcptepaddr;
		unsigned ptepindex;

		KASSERT(addr < UPT_MIN_ADDRESS,
		    ("pmap_copy: invalid to pmap_copy page tables"));

		pdnxt = (addr + NBPDR) & ~PDRMASK;
		if (pdnxt < addr)
			pdnxt = end_addr;
		ptepindex = addr >> PDRSHIFT;

		srcptepaddr = src_pmap->pm_pdir[ptepindex];
		if (srcptepaddr == 0)
			continue;

		if (srcptepaddr & PG_PS) {
			if (dst_pmap->pm_pdir[ptepindex] == 0 &&
			    ((srcptepaddr & PG_MANAGED) == 0 ||
			    pmap_pv_insert_pde(dst_pmap, addr, srcptepaddr &
			    PG_PS_FRAME))) {
				dst_pmap->pm_pdir[ptepindex] = srcptepaddr &
				    ~PG_W;
				dst_pmap->pm_stats.resident_count +=
				    NBPDR / PAGE_SIZE;
			}
			continue;
		}

		srcmpte = PHYS_TO_VM_PAGE(srcptepaddr & PG_FRAME);
		KASSERT(srcmpte->wire_count > 0,
		    ("pmap_copy: source page table page is unused"));

		if (pdnxt > end_addr)
			pdnxt = end_addr;

		src_pte = vtopte(addr);
		while (addr < pdnxt) {
			pt_entry_t ptetemp;
			ptetemp = *src_pte;
			/*
			 * we only virtual copy managed pages
			 */
			if ((ptetemp & PG_MANAGED) != 0) {
				dstmpte = pmap_allocpte(dst_pmap, addr,
				    M_NOWAIT);
				if (dstmpte == NULL)
					goto out;
				dst_pte = pmap_pte_quick(dst_pmap, addr);
				if (*dst_pte == 0 &&
				    pmap_try_insert_pv_entry(dst_pmap, addr,
				    PHYS_TO_VM_PAGE(ptetemp & PG_FRAME))) {
					/*
					 * Clear the wired, modified, and
					 * accessed (referenced) bits
					 * during the copy.
					 */
					*dst_pte = ptetemp & ~(PG_W | PG_M |
					    PG_A);
					dst_pmap->pm_stats.resident_count++;
	 			} else {
					free = NULL;
					if (pmap_unwire_pte_hold(dst_pmap,
					    dstmpte, &free)) {
						pmap_invalidate_page(dst_pmap,
						    addr);
						pmap_free_zero_pages(free);
					}
					goto out;
				}
				if (dstmpte->wire_count >= srcmpte->wire_count)
					break;
			}
			addr += PAGE_SIZE;
			src_pte++;
		}
	}
out:
	sched_unpin();
	vm_page_unlock_queues();
	PMAP_UNLOCK(src_pmap);
	PMAP_UNLOCK(dst_pmap);
}

static __inline void
pagezero(void *page)
{
#if defined(I686_CPU)
	if (cpu_class == CPUCLASS_686) {
#if defined(CPU_ENABLE_SSE)
		if (cpu_feature & CPUID_SSE2)
			sse2_pagezero(page);
		else
#endif
			i686_pagezero(page);
	} else
#endif
		bzero(page, PAGE_SIZE);
}

/*
 *	pmap_zero_page zeros the specified hardware page by mapping
 *	the page into KVM and using bzero to clear its contents.
 */
void
pmap_zero_page(vm_page_t m)
{
	struct sysmaps *sysmaps;

	sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)];
	mtx_lock(&sysmaps->lock);
	if (*sysmaps->CMAP2)
		panic("pmap_zero_page: CMAP2 busy");
	sched_pin();
	*sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(m) | PG_A | PG_M;
	invlcaddr(sysmaps->CADDR2);
	pagezero(sysmaps->CADDR2);
	*sysmaps->CMAP2 = 0;
	sched_unpin();
	mtx_unlock(&sysmaps->lock);
}

/*
 *	pmap_zero_page_area zeros the specified hardware page by mapping
 *	the page into KVM and using bzero to clear its contents.
 *
 *	off and size may not cover an area beyond a single hardware page.
 */
void
pmap_zero_page_area(vm_page_t m, int off, int size)
{
	struct sysmaps *sysmaps;

	sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)];
	mtx_lock(&sysmaps->lock);
	if (*sysmaps->CMAP2)
		panic("pmap_zero_page: CMAP2 busy");
	sched_pin();
	*sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(m) | PG_A | PG_M;
	invlcaddr(sysmaps->CADDR2);
	if (off == 0 && size == PAGE_SIZE)
		pagezero(sysmaps->CADDR2);
	else
		bzero((char *)sysmaps->CADDR2 + off, size);
	*sysmaps->CMAP2 = 0;
	sched_unpin();
	mtx_unlock(&sysmaps->lock);
}

/*
 *	pmap_zero_page_idle zeros the specified hardware page by mapping
 *	the page into KVM and using bzero to clear its contents.  This
 *	is intended to be called from the vm_pagezero process only and
 *	outside of Giant.
 */
void
pmap_zero_page_idle(vm_page_t m)
{

	if (*CMAP3)
		panic("pmap_zero_page: CMAP3 busy");
	sched_pin();
	*CMAP3 = PG_V | PG_RW | VM_PAGE_TO_PHYS(m) | PG_A | PG_M;
	invlcaddr(CADDR3);
	pagezero(CADDR3);
	*CMAP3 = 0;
	sched_unpin();
}

/*
 *	pmap_copy_page copies the specified (machine independent)
 *	page by mapping the page into virtual memory and using
 *	bcopy to copy the page, one machine dependent page at a
 *	time.
 */
void
pmap_copy_page(vm_page_t src, vm_page_t dst)
{
	struct sysmaps *sysmaps;

	sysmaps = &sysmaps_pcpu[PCPU_GET(cpuid)];
	mtx_lock(&sysmaps->lock);
	if (*sysmaps->CMAP1)
		panic("pmap_copy_page: CMAP1 busy");
	if (*sysmaps->CMAP2)
		panic("pmap_copy_page: CMAP2 busy");
	sched_pin();
	invlpg((u_int)sysmaps->CADDR1);
	invlpg((u_int)sysmaps->CADDR2);
	*sysmaps->CMAP1 = PG_V | VM_PAGE_TO_PHYS(src) | PG_A;
	*sysmaps->CMAP2 = PG_V | PG_RW | VM_PAGE_TO_PHYS(dst) | PG_A | PG_M;
	bcopy(sysmaps->CADDR1, sysmaps->CADDR2, PAGE_SIZE);
	*sysmaps->CMAP1 = 0;
	*sysmaps->CMAP2 = 0;
	sched_unpin();
	mtx_unlock(&sysmaps->lock);
}

/*
 * Returns true if the pmap's pv is one of the first
 * 16 pvs linked to from this page.  This count may
 * be changed upwards or downwards in the future; it
 * is only necessary that true be returned for a small
 * subset of pmaps for proper page aging.
 */
boolean_t
pmap_page_exists_quick(pmap_t pmap, vm_page_t m)
{
	struct md_page *pvh;
	pv_entry_t pv;
	int loops = 0;

	if (m->flags & PG_FICTITIOUS)
		return FALSE;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
		if (PV_PMAP(pv) == pmap) {
			return TRUE;
		}
		loops++;
		if (loops >= 16)
			break;
	}
	if (loops < 16) {
		pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
		TAILQ_FOREACH(pv, &pvh->pv_list, pv_list) {
			if (PV_PMAP(pv) == pmap)
				return (TRUE);
			loops++;
			if (loops >= 16)
				break;
		}
	}
	return (FALSE);
}

/*
 *	pmap_page_wired_mappings:
 *
 *	Return the number of managed mappings to the given physical page
 *	that are wired.
 */
int
pmap_page_wired_mappings(vm_page_t m)
{
	int count;

	count = 0;
	if ((m->flags & PG_FICTITIOUS) != 0)
		return (count);
	count = pmap_pvh_wired_mappings(&m->md, count);
	return (pmap_pvh_wired_mappings(pa_to_pvh(VM_PAGE_TO_PHYS(m)), count));
}

/*
 *	pmap_pvh_wired_mappings:
 *
 *	Return the updated number "count" of managed mappings that are wired.
 */
static int
pmap_pvh_wired_mappings(struct md_page *pvh, int count)
{
	pmap_t pmap;
	pt_entry_t *pte;
	pv_entry_t pv;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	sched_pin();
	TAILQ_FOREACH(pv, &pvh->pv_list, pv_list) {
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pte = pmap_pte_quick(pmap, pv->pv_va);
		if ((*pte & PG_W) != 0)
			count++;
		PMAP_UNLOCK(pmap);
	}
	sched_unpin();
	return (count);
}

/*
 * Returns TRUE if the given page is mapped individually or as part of
 * a 4mpage.  Otherwise, returns FALSE.
 */
boolean_t
pmap_page_is_mapped(vm_page_t m)
{
	struct md_page *pvh;

	if ((m->flags & (PG_FICTITIOUS | PG_UNMANAGED)) != 0)
		return (FALSE);
	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	if (TAILQ_EMPTY(&m->md.pv_list)) {
		pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
		return (!TAILQ_EMPTY(&pvh->pv_list));
	} else
		return (TRUE);
}

/*
 * Remove all pages from specified address space
 * this aids process exit speeds.  Also, this code
 * is special cased for current process only, but
 * can have the more generic (and slightly slower)
 * mode enabled.  This is much faster than pmap_remove
 * in the case of running down an entire address space.
 */
void
pmap_remove_pages(pmap_t pmap)
{
	pt_entry_t *pte, tpte;
	vm_page_t free = NULL;
	vm_page_t m, mpte, mt;
	pv_entry_t pv;
	struct md_page *pvh;
	struct pv_chunk *pc, *npc;
	int field, idx;
	int32_t bit;
	uint32_t inuse, bitmask;
	int allfree;

	if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) {
		printf("warning: pmap_remove_pages called with non-current pmap\n");
		return;
	}
	vm_page_lock_queues();
	PMAP_LOCK(pmap);
	sched_pin();
	TAILQ_FOREACH_SAFE(pc, &pmap->pm_pvchunk, pc_list, npc) {
		allfree = 1;
		for (field = 0; field < _NPCM; field++) {
			inuse = (~(pc->pc_map[field])) & pc_freemask[field];
			while (inuse != 0) {
				bit = bsfl(inuse);
				bitmask = 1UL << bit;
				idx = field * 32 + bit;
				pv = &pc->pc_pventry[idx];
				inuse &= ~bitmask;

				pte = pmap_pde(pmap, pv->pv_va);
				tpte = *pte;
				if ((tpte & PG_PS) == 0) {
					pte = vtopte(pv->pv_va);
					tpte = *pte & ~PG_PTE_PAT;
				}

				if (tpte == 0) {
					printf(
					    "TPTE at %p  IS ZERO @ VA %08x\n",
					    pte, pv->pv_va);
					panic("bad pte");
				}

/*
 * We cannot remove wired pages from a process' mapping at this time
 */
				if (tpte & PG_W) {
					allfree = 0;
					continue;
				}

				m = PHYS_TO_VM_PAGE(tpte & PG_FRAME);
				KASSERT(m->phys_addr == (tpte & PG_FRAME),
				    ("vm_page_t %p phys_addr mismatch %016jx %016jx",
				    m, (uintmax_t)m->phys_addr,
				    (uintmax_t)tpte));

				KASSERT(m < &vm_page_array[vm_page_array_size],
					("pmap_remove_pages: bad tpte %#jx",
					(uintmax_t)tpte));

				pte_clear(pte);

				/*
				 * Update the vm_page_t clean/reference bits.
				 */
				if ((tpte & (PG_M | PG_RW)) == (PG_M | PG_RW)) {
					if ((tpte & PG_PS) != 0) {
						for (mt = m; mt < &m[NBPDR / PAGE_SIZE]; mt++)
							vm_page_dirty(mt);
					} else
						vm_page_dirty(m);
				}

				/* Mark free */
				PV_STAT(pv_entry_frees++);
				PV_STAT(pv_entry_spare++);
				pv_entry_count--;
				pc->pc_map[field] |= bitmask;
				if ((tpte & PG_PS) != 0) {
					pmap->pm_stats.resident_count -= NBPDR / PAGE_SIZE;
					pvh = pa_to_pvh(tpte & PG_PS_FRAME);
					TAILQ_REMOVE(&pvh->pv_list, pv, pv_list);
					if (TAILQ_EMPTY(&pvh->pv_list)) {
						for (mt = m; mt < &m[NBPDR / PAGE_SIZE]; mt++)
							if (TAILQ_EMPTY(&mt->md.pv_list))
								vm_page_flag_clear(mt, PG_WRITEABLE);
					}
					mpte = pmap_lookup_pt_page(pmap, pv->pv_va);
					if (mpte != NULL) {
						pmap_remove_pt_page(pmap, mpte);
						pmap->pm_stats.resident_count--;
						KASSERT(mpte->wire_count == NPTEPG,
						    ("pmap_remove_pages: pte page wire count error"));
						mpte->wire_count = 0;
						pmap_add_delayed_free_list(mpte, &free, FALSE);
						atomic_subtract_int(&cnt.v_wire_count, 1);
					}
				} else {
					pmap->pm_stats.resident_count--;
					TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
					if (TAILQ_EMPTY(&m->md.pv_list)) {
						pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
						if (TAILQ_EMPTY(&pvh->pv_list))
							vm_page_flag_clear(m, PG_WRITEABLE);
					}
					pmap_unuse_pt(pmap, pv->pv_va, &free);
				}
			}
		}
		if (allfree) {
			PV_STAT(pv_entry_spare -= _NPCPV);
			PV_STAT(pc_chunk_count--);
			PV_STAT(pc_chunk_frees++);
			TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
			m = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)pc));
			pmap_qremove((vm_offset_t)pc, 1);
			vm_page_unwire(m, 0);
			vm_page_free(m);
			pmap_ptelist_free(&pv_vafree, (vm_offset_t)pc);
		}
	}
	sched_unpin();
	pmap_invalidate_all(pmap);
	vm_page_unlock_queues();
	PMAP_UNLOCK(pmap);
	pmap_free_zero_pages(free);
}

/*
 *	pmap_is_modified:
 *
 *	Return whether or not the specified physical page was modified
 *	in any physical maps.
 */
boolean_t
pmap_is_modified(vm_page_t m)
{

	if (m->flags & PG_FICTITIOUS)
		return (FALSE);
	if (pmap_is_modified_pvh(&m->md))
		return (TRUE);
	return (pmap_is_modified_pvh(pa_to_pvh(VM_PAGE_TO_PHYS(m))));
}

/*
 * Returns TRUE if any of the given mappings were used to modify
 * physical memory.  Otherwise, returns FALSE.  Both page and 2mpage
 * mappings are supported.
 */
static boolean_t
pmap_is_modified_pvh(struct md_page *pvh)
{
	pv_entry_t pv;
	pt_entry_t *pte;
	pmap_t pmap;
	boolean_t rv;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	rv = FALSE;
	sched_pin();
	TAILQ_FOREACH(pv, &pvh->pv_list, pv_list) {
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pte = pmap_pte_quick(pmap, pv->pv_va);
		rv = (*pte & (PG_M | PG_RW)) == (PG_M | PG_RW);
		PMAP_UNLOCK(pmap);
		if (rv)
			break;
	}
	sched_unpin();
	return (rv);
}

/*
 *	pmap_is_prefaultable:
 *
 *	Return whether or not the specified virtual address is elgible
 *	for prefault.
 */
boolean_t
pmap_is_prefaultable(pmap_t pmap, vm_offset_t addr)
{
	pd_entry_t *pde;
	pt_entry_t *pte;
	boolean_t rv;

	rv = FALSE;
	PMAP_LOCK(pmap);
	pde = pmap_pde(pmap, addr);
	if (*pde != 0 && (*pde & PG_PS) == 0) {
		pte = vtopte(addr);
		rv = *pte == 0;
	}
	PMAP_UNLOCK(pmap);
	return (rv);
}

/*
 * Clear the write and modified bits in each of the given page's mappings.
 */
void
pmap_remove_write(vm_page_t m)
{
	struct md_page *pvh;
	pv_entry_t next_pv, pv;
	pmap_t pmap;
	pd_entry_t *pde;
	pt_entry_t oldpte, *pte;
	vm_offset_t va;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	if ((m->flags & PG_FICTITIOUS) != 0 ||
	    (m->flags & PG_WRITEABLE) == 0)
		return;
	sched_pin();
	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
	TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_list, next_pv) {
		va = pv->pv_va;
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, va);
		if ((*pde & PG_RW) != 0)
			(void)pmap_demote_pde(pmap, pde, va);
		PMAP_UNLOCK(pmap);
	}
	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, pv->pv_va);
		KASSERT((*pde & PG_PS) == 0, ("pmap_clear_write: found"
		    " a 4mpage in page %p's pv list", m));
		pte = pmap_pte_quick(pmap, pv->pv_va);
retry:
		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);
	}
	vm_page_flag_clear(m, PG_WRITEABLE);
	sched_unpin();
}

/*
 *	pmap_ts_referenced:
 *
 *	Return a count of reference bits for a page, clearing those bits.
 *	It is not necessary for every reference bit to be cleared, but it
 *	is necessary that 0 only be returned when there are truly no
 *	reference bits set.
 *
 *	XXX: The exact number of bits to check and clear is a matter that
 *	should be tested and standardized at some point in the future for
 *	optimal aging of shared pages.
 */
int
pmap_ts_referenced(vm_page_t m)
{
	struct md_page *pvh;
	pv_entry_t pv, pvf, pvn;
	pmap_t pmap;
	pd_entry_t oldpde, *pde;
	pt_entry_t *pte;
	vm_offset_t va;
	int rtval = 0;

	if (m->flags & PG_FICTITIOUS)
		return (rtval);
	sched_pin();
	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
	TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_list, pvn) {
		va = pv->pv_va;
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, va);
		oldpde = *pde;
		if ((oldpde & PG_A) != 0) {
			if (pmap_demote_pde(pmap, pde, va)) {
				if ((oldpde & PG_W) == 0) {
					/*
					 * Remove the mapping to a single page
					 * so that a subsequent access may
					 * repromote.  Since the underlying
					 * page table page is fully populated,
					 * this removal never frees a page
					 * table page.
					 */
					va += VM_PAGE_TO_PHYS(m) - (oldpde &
					    PG_PS_FRAME);
					pmap_remove_page(pmap, va, NULL);
					rtval++;
					if (rtval > 4) {
						PMAP_UNLOCK(pmap);
						return (rtval);
					}
				}
			}
		}
		PMAP_UNLOCK(pmap);
	}
	if ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
		pvf = pv;
		do {
			pvn = TAILQ_NEXT(pv, pv_list);
			TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
			TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
			pmap = PV_PMAP(pv);
			PMAP_LOCK(pmap);
			pde = pmap_pde(pmap, pv->pv_va);
			KASSERT((*pde & PG_PS) == 0, ("pmap_ts_referenced:"
			    " found a 4mpage in page %p's pv list", m));
			pte = pmap_pte_quick(pmap, pv->pv_va);
			if ((*pte & PG_A) != 0) {
				atomic_clear_int((u_int *)pte, PG_A);
				pmap_invalidate_page(pmap, pv->pv_va);
				rtval++;
				if (rtval > 4)
					pvn = NULL;
			}
			PMAP_UNLOCK(pmap);
		} while ((pv = pvn) != NULL && pv != pvf);
	}
	sched_unpin();
	return (rtval);
}

/*
 *	Clear the modify bits on the specified physical page.
 */
void
pmap_clear_modify(vm_page_t m)
{
	struct md_page *pvh;
	pv_entry_t next_pv, pv;
	pmap_t pmap;
	pd_entry_t oldpde, *pde;
	pt_entry_t oldpte, *pte;
	vm_offset_t va;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	if ((m->flags & PG_FICTITIOUS) != 0)
		return;
	sched_pin();
	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
	TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_list, next_pv) {
		va = pv->pv_va;
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, va);
		oldpde = *pde;
		if ((oldpde & PG_RW) != 0) {
			if (pmap_demote_pde(pmap, pde, va)) {
				if ((oldpde & PG_W) == 0) {
					/*
					 * Write protect the mapping to a
					 * single page so that a subsequent
					 * write access may repromote.
					 */
					va += VM_PAGE_TO_PHYS(m) - (oldpde &
					    PG_PS_FRAME);
					pte = pmap_pte_quick(pmap, va);
					oldpte = *pte;
					if ((oldpte & PG_V) != 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.
						 */
						while (!atomic_cmpset_int((u_int *)pte,
						    oldpte,
						    oldpte & ~(PG_M | PG_RW)))
							oldpte = *pte;
						vm_page_dirty(m);
						pmap_invalidate_page(pmap, va);
					}
				}
			}
		}
		PMAP_UNLOCK(pmap);
	}
	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, pv->pv_va);
		KASSERT((*pde & PG_PS) == 0, ("pmap_clear_modify: found"
		    " a 4mpage in page %p's pv list", m));
		pte = pmap_pte_quick(pmap, pv->pv_va);
		if ((*pte & (PG_M | PG_RW)) == (PG_M | PG_RW)) {
			/*
			 * 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();
}

/*
 *	pmap_clear_reference:
 *
 *	Clear the reference bit on the specified physical page.
 */
void
pmap_clear_reference(vm_page_t m)
{
	struct md_page *pvh;
	pv_entry_t next_pv, pv;
	pmap_t pmap;
	pd_entry_t oldpde, *pde;
	pt_entry_t *pte;
	vm_offset_t va;

	mtx_assert(&vm_page_queue_mtx, MA_OWNED);
	if ((m->flags & PG_FICTITIOUS) != 0)
		return;
	sched_pin();
	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
	TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_list, next_pv) {
		va = pv->pv_va;
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, va);
		oldpde = *pde;
		if ((oldpde & PG_A) != 0) {
			if (pmap_demote_pde(pmap, pde, va)) {
				/*
				 * Remove the mapping to a single page so
				 * that a subsequent access may repromote.
				 * Since the underlying page table page is
				 * fully populated, this removal never frees
				 * a page table page.
				 */
				va += VM_PAGE_TO_PHYS(m) - (oldpde &
				    PG_PS_FRAME);
				pmap_remove_page(pmap, va, NULL);
			}
		}
		PMAP_UNLOCK(pmap);
	}
	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pde = pmap_pde(pmap, pv->pv_va);
		KASSERT((*pde & PG_PS) == 0, ("pmap_clear_reference: found"
		    " a 4mpage in page %p's pv list", m));
		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();
}

/*
 * Miscellaneous support routines follow
 */

/*
 * Map a set of physical memory pages into the kernel virtual
 * address space. Return a pointer to where it is mapped. This
 * routine is intended to be used for mapping device memory,
 * NOT real memory.
 */
void *
pmap_mapdev_attr(vm_paddr_t pa, vm_size_t size, int mode)
{
	vm_offset_t va, tmpva, offset;

	offset = pa & PAGE_MASK;
	size = roundup(offset + size, PAGE_SIZE);
	pa = pa & PG_FRAME;

	if (pa < KERNLOAD && pa + size <= KERNLOAD)
		va = KERNBASE + pa;
	else
		va = kmem_alloc_nofault(kernel_map, size);
	if (!va)
		panic("pmap_mapdev: Couldn't alloc kernel virtual memory");

	for (tmpva = va; size > 0; ) {
		pmap_kenter_attr(tmpva, pa, mode);
		size -= PAGE_SIZE;
		tmpva += PAGE_SIZE;
		pa += PAGE_SIZE;
	}
	pmap_invalidate_range(kernel_pmap, va, tmpva);
	pmap_invalidate_cache();
	return ((void *)(va + offset));
}

void *
pmap_mapdev(vm_paddr_t pa, vm_size_t size)
{

	return (pmap_mapdev_attr(pa, size, PAT_UNCACHEABLE));
}

void *
pmap_mapbios(vm_paddr_t pa, vm_size_t size)
{

	return (pmap_mapdev_attr(pa, size, PAT_WRITE_BACK));
}

void
pmap_unmapdev(vm_offset_t va, vm_size_t size)
{
	vm_offset_t base, offset, tmpva;

	if (va >= KERNBASE && va + size <= KERNBASE + KERNLOAD)
		return;
	base = trunc_page(va);
	offset = va & PAGE_MASK;
	size = roundup(offset + size, PAGE_SIZE);
	for (tmpva = base; tmpva < (base + size); tmpva += PAGE_SIZE)
		pmap_kremove(tmpva);
	pmap_invalidate_range(kernel_pmap, va, tmpva);
	kmem_free(kernel_map, base, size);
}

int
pmap_change_attr(vm_offset_t va, vm_size_t size, int mode)
{
	vm_offset_t base, offset, tmpva;
	pt_entry_t *pte;
	u_int opte, npte;
	pd_entry_t *pde;

	base = trunc_page(va);
	offset = va & PAGE_MASK;
	size = roundup(offset + size, PAGE_SIZE);

	/*
	 * Only supported on kernel virtual addresses above the recursive map.
	 */
	if (base < VM_MIN_KERNEL_ADDRESS)
		return (EINVAL);

	/* 4MB pages and pages that aren't mapped aren't supported. */
	for (tmpva = base; tmpva < (base + size); tmpva += PAGE_SIZE) {
		pde = pmap_pde(kernel_pmap, tmpva);
		if (*pde & PG_PS)
			return (EINVAL);
		if (*pde == 0)
			return (EINVAL);
		pte = vtopte(tmpva);
		if (*pte == 0)
			return (EINVAL);
	}

	/*
	 * Ok, all the pages exist and are 4k, so run through them updating
	 * their cache mode.
	 */
	for (tmpva = base; size > 0; ) {
		pte = vtopte(tmpva);

		/*
		 * The cache mode bits are all in the low 32-bits of the
		 * PTE, so we can just spin on updating the low 32-bits.
		 */
		do {
			opte = *(u_int *)pte;
			npte = opte & ~(PG_PTE_PAT | PG_NC_PCD | PG_NC_PWT);
			npte |= pmap_cache_bits(mode, 0);
		} while (npte != opte &&
		    !atomic_cmpset_int((u_int *)pte, opte, npte));
		tmpva += PAGE_SIZE;
		size -= PAGE_SIZE;
	}

	/*
	 * Flush CPU caches to make sure any data isn't cached that shouldn't
	 * be, etc.
	 */
	pmap_invalidate_range(kernel_pmap, base, tmpva);
	pmap_invalidate_cache();
	return (0);
}

/*
 * perform the pmap work for mincore
 */
int
pmap_mincore(pmap_t pmap, vm_offset_t addr)
{
	pd_entry_t *pdep;
	pt_entry_t *ptep, pte;
	vm_paddr_t pa;
	vm_page_t m;
	int val = 0;

	PMAP_LOCK(pmap);
	pdep = pmap_pde(pmap, addr);
	if (*pdep != 0) {
		if (*pdep & PG_PS) {
			pte = *pdep;
			val = MINCORE_SUPER;
			/* Compute the physical address of the 4KB page. */
			pa = ((*pdep & PG_PS_FRAME) | (addr & PDRMASK)) &
			    PG_FRAME;
		} else {
			ptep = pmap_pte(pmap, addr);
			pte = *ptep;
			pmap_pte_release(ptep);
			pa = pte & PG_FRAME;
		}
	} else {
		pte = 0;
		pa = 0;
	}
	PMAP_UNLOCK(pmap);

	if (pte != 0) {
		val |= MINCORE_INCORE;
		if ((pte & PG_MANAGED) == 0)
			return val;

		m = PHYS_TO_VM_PAGE(pa);

		/*
		 * Modified by us
		 */
		if ((pte & (PG_M | PG_RW)) == (PG_M | PG_RW))
			val |= MINCORE_MODIFIED|MINCORE_MODIFIED_OTHER;
		else {
			/*
			 * Modified by someone else
			 */
			vm_page_lock_queues();
			if (m->dirty || pmap_is_modified(m))
				val |= MINCORE_MODIFIED_OTHER;
			vm_page_unlock_queues();
		}
		/*
		 * Referenced by us
		 */
		if (pte & PG_A)
			val |= MINCORE_REFERENCED|MINCORE_REFERENCED_OTHER;
		else {
			/*
			 * Referenced by someone else
			 */
			vm_page_lock_queues();
			if ((m->flags & PG_REFERENCED) ||
			    pmap_ts_referenced(m)) {
				val |= MINCORE_REFERENCED_OTHER;
				vm_page_flag_set(m, PG_REFERENCED);
			}
			vm_page_unlock_queues();
		}
	}
	return val;
}

void
pmap_activate(struct thread *td)
{
	pmap_t	pmap, oldpmap;
	u_int32_t  cr3;

	critical_enter();
	pmap = vmspace_pmap(td->td_proc->p_vmspace);
	oldpmap = PCPU_GET(curpmap);
#if defined(SMP)
	atomic_clear_int(&oldpmap->pm_active, PCPU_GET(cpumask));
	atomic_set_int(&pmap->pm_active, PCPU_GET(cpumask));
#else
	oldpmap->pm_active &= ~1;
	pmap->pm_active |= 1;
#endif
#ifdef PAE
	cr3 = vtophys(pmap->pm_pdpt);
#else
	cr3 = vtophys(pmap->pm_pdir);
#endif
	/*
	 * pmap_activate is for the current thread on the current cpu
	 */
	td->td_pcb->pcb_cr3 = cr3;
	load_cr3(cr3);
	PCPU_SET(curpmap, pmap);
	critical_exit();
}

/*
 *	Increase the starting virtual address of the given mapping if a
 *	different alignment might result in more superpage mappings.
 */
void
pmap_align_superpage(vm_object_t object, vm_ooffset_t offset,
    vm_offset_t *addr, vm_size_t size)
{
	vm_offset_t superpage_offset;

	if (size < NBPDR)
		return;
	if (object != NULL && (object->flags & OBJ_COLORED) != 0)
		offset += ptoa(object->pg_color);
	superpage_offset = offset & PDRMASK;
	if (size - ((NBPDR - superpage_offset) & PDRMASK) < NBPDR ||
	    (*addr & PDRMASK) == superpage_offset)
		return;
	if ((*addr & PDRMASK) < superpage_offset)
		*addr = (*addr & ~PDRMASK) + superpage_offset;
	else
		*addr = ((*addr + PDRMASK) & ~PDRMASK) + superpage_offset;
}


#if defined(PMAP_DEBUG)
pmap_pid_dump(int pid)
{
	pmap_t pmap;
	struct proc *p;
	int npte = 0;
	int index;

	sx_slock(&allproc_lock);
	FOREACH_PROC_IN_SYSTEM(p) {
		if (p->p_pid != pid)
			continue;

		if (p->p_vmspace) {
			int i,j;
			index = 0;
			pmap = vmspace_pmap(p->p_vmspace);
			for (i = 0; i < NPDEPTD; i++) {
				pd_entry_t *pde;
				pt_entry_t *pte;
				vm_offset_t base = i << PDRSHIFT;

				pde = &pmap->pm_pdir[i];
				if (pde && pmap_pde_v(pde)) {
					for (j = 0; j < NPTEPG; j++) {
						vm_offset_t va = base + (j << PAGE_SHIFT);
						if (va >= (vm_offset_t) VM_MIN_KERNEL_ADDRESS) {
							if (index) {
								index = 0;
								printf("\n");
							}
							sx_sunlock(&allproc_lock);
							return npte;
						}
						pte = pmap_pte(pmap, va);
						if (pte && pmap_pte_v(pte)) {
							pt_entry_t pa;
							vm_page_t m;
							pa = *pte;
							m = PHYS_TO_VM_PAGE(pa & PG_FRAME);
							printf("va: 0x%x, pt: 0x%x, h: %d, w: %d, f: 0x%x",
								va, pa, m->hold_count, m->wire_count, m->flags);
							npte++;
							index++;
							if (index >= 2) {
								index = 0;
								printf("\n");
							} else {
								printf(" ");
							}
						}
					}
				}
			}
		}
	}
	sx_sunlock(&allproc_lock);
	return npte;
}
#endif

#if defined(DEBUG)

static void	pads(pmap_t pm);
void		pmap_pvdump(vm_offset_t pa);

/* print address space of pmap*/
static void
pads(pmap_t pm)
{
	int i, j;
	vm_paddr_t va;
	pt_entry_t *ptep;

	if (pm == kernel_pmap)
		return;
	for (i = 0; i < NPDEPTD; i++)
		if (pm->pm_pdir[i])
			for (j = 0; j < NPTEPG; j++) {
				va = (i << PDRSHIFT) + (j << PAGE_SHIFT);
				if (pm == kernel_pmap && va < KERNBASE)
					continue;
				if (pm != kernel_pmap && va > UPT_MAX_ADDRESS)
					continue;
				ptep = pmap_pte(pm, va);
				if (pmap_pte_v(ptep))
					printf("%x:%x ", va, *ptep);
			};

}

void
pmap_pvdump(vm_paddr_t pa)
{
	pv_entry_t pv;
	pmap_t pmap;
	vm_page_t m;

	printf("pa %x", pa);
	m = PHYS_TO_VM_PAGE(pa);
	TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
		pmap = PV_PMAP(pv);
		printf(" -> pmap %p, va %x", (void *)pmap, pv->pv_va);
		pads(pmap);
	}
	printf(" ");
}
#endif