kernel - pmap->pm_spin now uses a shared spinlock

[dragonfly.git] / sys / platform / pc64 / x86_64 / pmap.c

/*
 * Copyright (c) 1991 Regents of the University of California.
 * Copyright (c) 1994 John S. Dyson
 * Copyright (c) 1994 David Greenman
 * Copyright (c) 2003 Peter Wemm
 * Copyright (c) 2005-2008 Alan L. Cox <alc@cs.rice.edu>
 * Copyright (c) 2008, 2009 The DragonFly Project.
 * Copyright (c) 2008, 2009 Jordan Gordeev.
 * Copyright (c) 2011-2017 Matthew Dillon
 * 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.
 */
/*
 * Manage physical address maps for x86-64 systems.
 */

#if 0 /* JG */
#include "opt_disable_pse.h"
#include "opt_pmap.h"
#endif
#include "opt_msgbuf.h"

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/msgbuf.h>
#include <sys/vmmeter.h>
#include <sys/mman.h>
#include <sys/systm.h>

#include <vm/vm.h>
#include <vm/vm_param.h>
#include <sys/sysctl.h>
#include <sys/lock.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_zone.h>

#include <sys/user.h>
#include <sys/thread2.h>
#include <sys/sysref2.h>
#include <sys/spinlock2.h>
#include <vm/vm_page2.h>

#include <machine/cputypes.h>
#include <machine/md_var.h>
#include <machine/specialreg.h>
#include <machine/smp.h>
#include <machine_base/apic/apicreg.h>
#include <machine/globaldata.h>
#include <machine/pmap.h>
#include <machine/pmap_inval.h>
#include <machine/inttypes.h>

#include <ddb/ddb.h>

#define PMAP_KEEP_PDIRS
#ifndef PMAP_SHPGPERPROC
#define PMAP_SHPGPERPROC 2000
#endif

#if defined(DIAGNOSTIC)
#define PMAP_DIAGNOSTIC
#endif

#define MINPV 2048

/*
 * pmap debugging will report who owns a pv lock when blocking.
 */
#ifdef PMAP_DEBUG

#define PMAP_DEBUG_DECL         ,const char *func, int lineno
#define PMAP_DEBUG_ARGS         , __func__, __LINE__
#define PMAP_DEBUG_COPY         , func, lineno

#define pv_get(pmap, pindex, pmarkp)    _pv_get(pmap, pindex, pmarkp    \
                                                        PMAP_DEBUG_ARGS)
#define pv_lock(pv)                     _pv_lock(pv                     \
                                                        PMAP_DEBUG_ARGS)
#define pv_hold_try(pv)                 _pv_hold_try(pv                 \
                                                        PMAP_DEBUG_ARGS)
#define pv_alloc(pmap, pindex, isnewp)  _pv_alloc(pmap, pindex, isnewp  \
                                                        PMAP_DEBUG_ARGS)

#define pv_free(pv, pvp)                _pv_free(pv, pvp PMAP_DEBUG_ARGS)

#else

#define PMAP_DEBUG_DECL
#define PMAP_DEBUG_ARGS
#define PMAP_DEBUG_COPY

#define pv_get(pmap, pindex, pmarkp)            _pv_get(pmap, pindex, pmarkp)
#define pv_lock(pv)                     _pv_lock(pv)
#define pv_hold_try(pv)                 _pv_hold_try(pv)
#define pv_alloc(pmap, pindex, isnewp)  _pv_alloc(pmap, pindex, isnewp)
#define pv_free(pv, pvp)                _pv_free(pv, pvp)

#endif

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

#define pmap_pde_v(pmap, pte)           ((*(pd_entry_t *)pte & pmap->pmap_bits[PG_V_IDX]) != 0)
#define pmap_pte_w(pmap, pte)           ((*(pt_entry_t *)pte & pmap->pmap_bits[PG_W_IDX]) != 0)
#define pmap_pte_m(pmap, pte)           ((*(pt_entry_t *)pte & pmap->pmap_bits[PG_M_IDX]) != 0)
#define pmap_pte_u(pmap, pte)           ((*(pt_entry_t *)pte & pmap->pmap_bits[PG_U_IDX]) != 0)
#define pmap_pte_v(pmap, pte)           ((*(pt_entry_t *)pte & pmap->pmap_bits[PG_V_IDX]) != 0)

/*
 * Given a map and a machine independent protection code,
 * convert to a vax protection code.
 */
#define pte_prot(m, p)          \
        (m->protection_codes[p & (VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE)])
static uint64_t protection_codes[PROTECTION_CODES_SIZE];

struct pmap kernel_pmap;

MALLOC_DEFINE(M_OBJPMAP, "objpmap", "pmaps associated with VM objects");

vm_paddr_t avail_start;         /* PA of first available physical page */
vm_paddr_t avail_end;           /* PA of last available physical page */
vm_offset_t virtual2_start;     /* cutout free area prior to kernel start */
vm_offset_t virtual2_end;
vm_offset_t virtual_start;      /* VA of first avail page (after kernel bss) */
vm_offset_t virtual_end;        /* VA of last avail page (end of kernel AS) */
vm_offset_t KvaStart;           /* VA start of KVA space */
vm_offset_t KvaEnd;             /* VA end of KVA space (non-inclusive) */
vm_offset_t KvaSize;            /* max size of kernel virtual address space */
static boolean_t pmap_initialized = FALSE;      /* Has pmap_init completed? */
//static int pgeflag;           /* PG_G or-in */
//static int pseflag;           /* PG_PS or-in */
uint64_t PatMsr;

static int ndmpdp;
static vm_paddr_t dmaplimit;
static int nkpt;
vm_offset_t kernel_vm_end = VM_MIN_KERNEL_ADDRESS;

static pt_entry_t pat_pte_index[PAT_INDEX_SIZE];        /* PAT -> PG_ bits */
/*static pt_entry_t pat_pde_index[PAT_INDEX_SIZE];*/    /* PAT -> PG_ bits */

static uint64_t KPTbase;
static uint64_t KPTphys;
static uint64_t KPDphys;        /* phys addr of kernel level 2 */
static uint64_t KPDbase;        /* phys addr of kernel level 2 @ KERNBASE */
uint64_t KPDPphys;      /* phys addr of kernel level 3 */
uint64_t KPML4phys;     /* phys addr of kernel level 4 */

static uint64_t DMPDphys;       /* phys addr of direct mapped level 2 */
static uint64_t DMPDPphys;      /* phys addr of direct mapped level 3 */

/*
 * Data for the pv entry allocation mechanism
 */
static vm_zone_t pvzone;
static struct vm_zone pvzone_store;
static int pv_entry_max=0, pv_entry_high_water=0;
static int pmap_pagedaemon_waken = 0;
static struct pv_entry *pvinit;

/*
 * All those kernel PT submaps that BSD is so fond of
 */
pt_entry_t *CMAP1 = NULL, *ptmmap;
caddr_t CADDR1 = NULL, ptvmmap = NULL;
static pt_entry_t *msgbufmap;
struct msgbuf *msgbufp=NULL;

/*
 * PMAP default PG_* bits. Needed to be able to add
 * EPT/NPT pagetable pmap_bits for the VMM module
 */
uint64_t pmap_bits_default[] = {
                REGULAR_PMAP,                   /* TYPE_IDX             0 */
                X86_PG_V,                       /* PG_V_IDX             1 */
                X86_PG_RW,                      /* PG_RW_IDX            2 */
                X86_PG_U,                       /* PG_U_IDX             3 */
                X86_PG_A,                       /* PG_A_IDX             4 */
                X86_PG_M,                       /* PG_M_IDX             5 */
                X86_PG_PS,                      /* PG_PS_IDX3           6 */
                X86_PG_G,                       /* PG_G_IDX             7 */
                X86_PG_AVAIL1,                  /* PG_AVAIL1_IDX        8 */
                X86_PG_AVAIL2,                  /* PG_AVAIL2_IDX        9 */
                X86_PG_AVAIL3,                  /* PG_AVAIL3_IDX        10 */
                X86_PG_NC_PWT | X86_PG_NC_PCD,  /* PG_N_IDX             11 */
                X86_PG_NX,                      /* PG_NX_IDX            12 */
};
/*
 * Crashdump maps.
 */
static pt_entry_t *pt_crashdumpmap;
static caddr_t crashdumpmap;

static int pmap_debug = 0;
SYSCTL_INT(_machdep, OID_AUTO, pmap_debug, CTLFLAG_RW,
    &pmap_debug, 0, "Debug pmap's");
#ifdef PMAP_DEBUG2
static int pmap_enter_debug = 0;
SYSCTL_INT(_machdep, OID_AUTO, pmap_enter_debug, CTLFLAG_RW,
    &pmap_enter_debug, 0, "Debug pmap_enter's");
#endif
static int pmap_yield_count = 64;
SYSCTL_INT(_machdep, OID_AUTO, pmap_yield_count, CTLFLAG_RW,
    &pmap_yield_count, 0, "Yield during init_pt/release");
static int pmap_mmu_optimize = 0;
SYSCTL_INT(_machdep, OID_AUTO, pmap_mmu_optimize, CTLFLAG_RW,
    &pmap_mmu_optimize, 0, "Share page table pages when possible");
int pmap_fast_kernel_cpusync = 0;
SYSCTL_INT(_machdep, OID_AUTO, pmap_fast_kernel_cpusync, CTLFLAG_RW,
    &pmap_fast_kernel_cpusync, 0, "Share page table pages when possible");
int pmap_dynamic_delete = 0;
SYSCTL_INT(_machdep, OID_AUTO, pmap_dynamic_delete, CTLFLAG_RW,
    &pmap_dynamic_delete, 0, "Dynamically delete PT/PD/PDPs");

static int pmap_nx_enable = 0;
/* needs manual TUNABLE in early probe, see below */

#define DISABLE_PSE

/* Standard user access funtions */
extern int std_copyinstr (const void *udaddr, void *kaddr, size_t len,
    size_t *lencopied);
extern int std_copyin (const void *udaddr, void *kaddr, size_t len);
extern int std_copyout (const void *kaddr, void *udaddr, size_t len);
extern int std_fubyte (const uint8_t *base);
extern int std_subyte (uint8_t *base, uint8_t byte);
extern int32_t std_fuword32 (const uint32_t *base);
extern int64_t std_fuword64 (const uint64_t *base);
extern int std_suword64 (uint64_t *base, uint64_t word);
extern int std_suword32 (uint32_t *base, int word);
extern uint32_t std_swapu32 (volatile uint32_t *base, uint32_t v);
extern uint64_t std_swapu64 (volatile uint64_t *base, uint64_t v);

static void pv_hold(pv_entry_t pv);
static int _pv_hold_try(pv_entry_t pv
                                PMAP_DEBUG_DECL);
static void pv_drop(pv_entry_t pv);
static void _pv_lock(pv_entry_t pv
                                PMAP_DEBUG_DECL);
static void pv_unlock(pv_entry_t pv);
static pv_entry_t _pv_alloc(pmap_t pmap, vm_pindex_t pindex, int *isnew
                                PMAP_DEBUG_DECL);
static pv_entry_t _pv_get(pmap_t pmap, vm_pindex_t pindex, vm_pindex_t **pmarkp
                                PMAP_DEBUG_DECL);
static void _pv_free(pv_entry_t pv, pv_entry_t pvp PMAP_DEBUG_DECL);
static pv_entry_t pv_get_try(pmap_t pmap, vm_pindex_t pindex,
                                vm_pindex_t **pmarkp, int *errorp);
static void pv_put(pv_entry_t pv);
static void *pv_pte_lookup(pv_entry_t pv, vm_pindex_t pindex);
static pv_entry_t pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex,
                      pv_entry_t *pvpp);
static pv_entry_t pmap_allocpte_seg(pmap_t pmap, vm_pindex_t ptepindex,
                      pv_entry_t *pvpp, vm_map_entry_t entry, vm_offset_t va);
static void pmap_remove_pv_pte(pv_entry_t pv, pv_entry_t pvp,
                        pmap_inval_bulk_t *bulk, int destroy);
static vm_page_t pmap_remove_pv_page(pv_entry_t pv);
static int pmap_release_pv(pv_entry_t pv, pv_entry_t pvp,
                        pmap_inval_bulk_t *bulk);

struct pmap_scan_info;
static void pmap_remove_callback(pmap_t pmap, struct pmap_scan_info *info,
                      pv_entry_t pte_pv, vm_pindex_t *pte_placemark,
                      pv_entry_t pt_pv, int sharept,
                      vm_offset_t va, pt_entry_t *ptep, void *arg __unused);
static void pmap_protect_callback(pmap_t pmap, struct pmap_scan_info *info,
                      pv_entry_t pte_pv, vm_pindex_t *pte_placemark,
                      pv_entry_t pt_pv, int sharept,
                      vm_offset_t va, pt_entry_t *ptep, void *arg __unused);

static void i386_protection_init (void);
static void create_pagetables(vm_paddr_t *firstaddr);
static void pmap_remove_all (vm_page_t m);
static boolean_t pmap_testbit (vm_page_t m, int bit);

static pt_entry_t * pmap_pte_quick (pmap_t pmap, vm_offset_t va);
static vm_offset_t pmap_kmem_choose(vm_offset_t addr);

static void pmap_pinit_defaults(struct pmap *pmap);
static void pv_placemarker_wait(pmap_t pmap, vm_pindex_t *pmark);
static void pv_placemarker_wakeup(pmap_t pmap, vm_pindex_t *pmark);

static unsigned pdir4mb;

static int
pv_entry_compare(pv_entry_t pv1, pv_entry_t pv2)
{
        if (pv1->pv_pindex < pv2->pv_pindex)
                return(-1);
        if (pv1->pv_pindex > pv2->pv_pindex)
                return(1);
        return(0);
}

RB_GENERATE2(pv_entry_rb_tree, pv_entry, pv_entry,
             pv_entry_compare, vm_pindex_t, pv_pindex);

static __inline
void
pmap_page_stats_adding(vm_page_t m)
{
        globaldata_t gd = mycpu;

        if (TAILQ_EMPTY(&m->md.pv_list)) {
                ++gd->gd_vmtotal.t_arm;
        } else if (TAILQ_FIRST(&m->md.pv_list) ==
                   TAILQ_LAST(&m->md.pv_list, md_page_pv_list)) {
                ++gd->gd_vmtotal.t_armshr;
                ++gd->gd_vmtotal.t_avmshr;
        } else {
                ++gd->gd_vmtotal.t_avmshr;
        }
}

static __inline
void
pmap_page_stats_deleting(vm_page_t m)
{
        globaldata_t gd = mycpu;

        if (TAILQ_EMPTY(&m->md.pv_list)) {
                --gd->gd_vmtotal.t_arm;
        } else if (TAILQ_FIRST(&m->md.pv_list) ==
                   TAILQ_LAST(&m->md.pv_list, md_page_pv_list)) {
                --gd->gd_vmtotal.t_armshr;
                --gd->gd_vmtotal.t_avmshr;
        } else {
                --gd->gd_vmtotal.t_avmshr;
        }
}

/*
 * Move the kernel virtual free pointer to the next
 * 2MB.  This is used to help improve performance
 * by using a large (2MB) 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;

        newaddr = roundup2(addr, NBPDR);
        return newaddr;
}

/*
 * pmap_pte_quick:
 *
 *      Super fast pmap_pte routine best used when scanning the pv lists.
 *      This eliminates many course-grained invltlb calls.  Note that many of
 *      the pv list scans are across different pmaps and it is very wasteful
 *      to do an entire invltlb when checking a single mapping.
 */
static __inline pt_entry_t *pmap_pte(pmap_t pmap, vm_offset_t va);

static
pt_entry_t *
pmap_pte_quick(pmap_t pmap, vm_offset_t va)
{
        return pmap_pte(pmap, va);
}

/*
 * Returns the pindex of a page table entry (representing a terminal page).
 * There are NUPTE_TOTAL page table entries possible (a huge number)
 *
 * x86-64 has a 48-bit address space, where bit 47 is sign-extended out.
 * We want to properly translate negative KVAs.
 */
static __inline
vm_pindex_t
pmap_pte_pindex(vm_offset_t va)
{
        return ((va >> PAGE_SHIFT) & (NUPTE_TOTAL - 1));
}

/*
 * Returns the pindex of a page table.
 */
static __inline
vm_pindex_t
pmap_pt_pindex(vm_offset_t va)
{
        return (NUPTE_TOTAL + ((va >> PDRSHIFT) & (NUPT_TOTAL - 1)));
}

/*
 * Returns the pindex of a page directory.
 */
static __inline
vm_pindex_t
pmap_pd_pindex(vm_offset_t va)
{
        return (NUPTE_TOTAL + NUPT_TOTAL +
                ((va >> PDPSHIFT) & (NUPD_TOTAL - 1)));
}

static __inline
vm_pindex_t
pmap_pdp_pindex(vm_offset_t va)
{
        return (NUPTE_TOTAL + NUPT_TOTAL + NUPD_TOTAL +
                ((va >> PML4SHIFT) & (NUPDP_TOTAL - 1)));
}

static __inline
vm_pindex_t
pmap_pml4_pindex(void)
{
        return (NUPTE_TOTAL + NUPT_TOTAL + NUPD_TOTAL + NUPDP_TOTAL);
}

/*
 * Return various clipped indexes for a given VA
 *
 * Returns the index of a pt in a page directory, representing a page
 * table.
 */
static __inline
vm_pindex_t
pmap_pt_index(vm_offset_t va)
{
        return ((va >> PDRSHIFT) & ((1ul << NPDEPGSHIFT) - 1));
}

/*
 * Returns the index of a pd in a page directory page, representing a page
 * directory.
 */
static __inline
vm_pindex_t
pmap_pd_index(vm_offset_t va)
{
        return ((va >> PDPSHIFT) & ((1ul << NPDPEPGSHIFT) - 1));
}

/*
 * Returns the index of a pdp in the pml4 table, representing a page
 * directory page.
 */
static __inline
vm_pindex_t
pmap_pdp_index(vm_offset_t va)
{
        return ((va >> PML4SHIFT) & ((1ul << NPML4EPGSHIFT) - 1));
}

/*
 * The placemarker hash must be broken up into four zones so lock
 * ordering semantics continue to work (e.g. pte, pt, pd, then pdp).
 *
 * Placemarkers are used to 'lock' page table indices that do not have
 * a pv_entry.  This allows the pmap to support managed and unmanaged
 * pages and shared page tables.
 */
#define PM_PLACE_BASE   (PM_PLACEMARKS >> 2)

static __inline
vm_pindex_t *
pmap_placemarker_hash(pmap_t pmap, vm_pindex_t pindex)
{
        int hi;

        if (pindex < pmap_pt_pindex(0))         /* zone 0 - PTE */
                hi = 0;
        else if (pindex < pmap_pd_pindex(0))    /* zone 1 - PT */
                hi = PM_PLACE_BASE;
        else if (pindex < pmap_pdp_pindex(0))   /* zone 2 - PD */
                hi = PM_PLACE_BASE << 1;
        else                                    /* zone 3 - PDP (and PML4E) */
                hi = PM_PLACE_BASE | (PM_PLACE_BASE << 1);
        hi += pindex & (PM_PLACE_BASE - 1);

        return (&pmap->pm_placemarks[hi]);
}


/*
 * Generic procedure to index a pte from a pt, pd, or pdp.
 *
 * NOTE: Normally passed pindex as pmap_xx_index().  pmap_xx_pindex() is NOT
 *       a page table page index but is instead of PV lookup index.
 */
static
void *
pv_pte_lookup(pv_entry_t pv, vm_pindex_t pindex)
{
        pt_entry_t *pte;

        pte = (pt_entry_t *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(pv->pv_m));
        return(&pte[pindex]);
}

/*
 * Return pointer to PDP slot in the PML4
 */
static __inline
pml4_entry_t *
pmap_pdp(pmap_t pmap, vm_offset_t va)
{
        return (&pmap->pm_pml4[pmap_pdp_index(va)]);
}

/*
 * Return pointer to PD slot in the PDP given a pointer to the PDP
 */
static __inline
pdp_entry_t *
pmap_pdp_to_pd(pml4_entry_t pdp_pte, vm_offset_t va)
{
        pdp_entry_t *pd;

        pd = (pdp_entry_t *)PHYS_TO_DMAP(pdp_pte & PG_FRAME);
        return (&pd[pmap_pd_index(va)]);
}

/*
 * Return pointer to PD slot in the PDP.
 */
static __inline
pdp_entry_t *
pmap_pd(pmap_t pmap, vm_offset_t va)
{
        pml4_entry_t *pdp;

        pdp = pmap_pdp(pmap, va);
        if ((*pdp & pmap->pmap_bits[PG_V_IDX]) == 0)
                return NULL;
        return (pmap_pdp_to_pd(*pdp, va));
}

/*
 * Return pointer to PT slot in the PD given a pointer to the PD
 */
static __inline
pd_entry_t *
pmap_pd_to_pt(pdp_entry_t pd_pte, vm_offset_t va)
{
        pd_entry_t *pt;

        pt = (pd_entry_t *)PHYS_TO_DMAP(pd_pte & PG_FRAME);
        return (&pt[pmap_pt_index(va)]);
}

/*
 * Return pointer to PT slot in the PD
 *
 * SIMPLE PMAP NOTE: Simple pmaps (embedded in objects) do not have PDPs,
 *                   so we cannot lookup the PD via the PDP.  Instead we
 *                   must look it up via the pmap.
 */
static __inline
pd_entry_t *
pmap_pt(pmap_t pmap, vm_offset_t va)
{
        pdp_entry_t *pd;
        pv_entry_t pv;
        vm_pindex_t pd_pindex;
        vm_paddr_t phys;

        if (pmap->pm_flags & PMAP_FLAG_SIMPLE) {
                pd_pindex = pmap_pd_pindex(va);
                spin_lock_shared(&pmap->pm_spin);
                pv = pv_entry_rb_tree_RB_LOOKUP(&pmap->pm_pvroot, pd_pindex);
                if (pv == NULL || pv->pv_m == NULL) {
                        spin_unlock_shared(&pmap->pm_spin);
                        return NULL;
                }
                phys = VM_PAGE_TO_PHYS(pv->pv_m);
                spin_unlock_shared(&pmap->pm_spin);
                return (pmap_pd_to_pt(phys, va));
        } else {
                pd = pmap_pd(pmap, va);
                if (pd == NULL || (*pd & pmap->pmap_bits[PG_V_IDX]) == 0)
                         return NULL;
                return (pmap_pd_to_pt(*pd, va));
        }
}

/*
 * Return pointer to PTE slot in the PT given a pointer to the PT
 */
static __inline
pt_entry_t *
pmap_pt_to_pte(pd_entry_t pt_pte, vm_offset_t va)
{
        pt_entry_t *pte;

        pte = (pt_entry_t *)PHYS_TO_DMAP(pt_pte & PG_FRAME);
        return (&pte[pmap_pte_index(va)]);
}

/*
 * Return pointer to PTE slot in the PT
 */
static __inline
pt_entry_t *
pmap_pte(pmap_t pmap, vm_offset_t va)
{
        pd_entry_t *pt;

        pt = pmap_pt(pmap, va);
        if (pt == NULL || (*pt & pmap->pmap_bits[PG_V_IDX]) == 0)
                 return NULL;
        if ((*pt & pmap->pmap_bits[PG_PS_IDX]) != 0)
                return ((pt_entry_t *)pt);
        return (pmap_pt_to_pte(*pt, va));
}

/*
 * Of all the layers (PTE, PT, PD, PDP, PML4) the best one to cache is
 * the PT layer.  This will speed up core pmap operations considerably.
 *
 * NOTE: The pmap spinlock does not need to be held but the passed-in pv
 *       must be in a known associated state (typically by being locked when
 *       the pmap spinlock isn't held).  We allow the race for that case.
 *
 * NOTE: pm_pvhint is only accessed (read) with the spin-lock held, using
 *       cpu_ccfence() to prevent compiler optimizations from reloading the
 *       field.
 */
static __inline
void
pv_cache(pv_entry_t pv, vm_pindex_t pindex)
{
        if (pindex >= pmap_pt_pindex(0) && pindex < pmap_pd_pindex(0)) {
                if (pv->pv_pmap)
                        pv->pv_pmap->pm_pvhint = pv;
        }
}


/*
 * Return address of PT slot in PD (KVM only)
 *
 * Cannot be used for user page tables because it might interfere with
 * the shared page-table-page optimization (pmap_mmu_optimize).
 */
static __inline
pd_entry_t *
vtopt(vm_offset_t va)
{
        uint64_t mask = ((1ul << (NPDEPGSHIFT + NPDPEPGSHIFT +
                                  NPML4EPGSHIFT)) - 1);

        return (PDmap + ((va >> PDRSHIFT) & mask));
}

/*
 * KVM - return address of PTE slot in PT
 */
static __inline
pt_entry_t *
vtopte(vm_offset_t va)
{
        uint64_t mask = ((1ul << (NPTEPGSHIFT + NPDEPGSHIFT +
                                  NPDPEPGSHIFT + NPML4EPGSHIFT)) - 1);

        return (PTmap + ((va >> PAGE_SHIFT) & mask));
}

static uint64_t
allocpages(vm_paddr_t *firstaddr, long n)
{
        uint64_t ret;

        ret = *firstaddr;
        bzero((void *)ret, n * PAGE_SIZE);
        *firstaddr += n * PAGE_SIZE;
        return (ret);
}

static
void
create_pagetables(vm_paddr_t *firstaddr)
{
        long i;         /* must be 64 bits */
        long nkpt_base;
        long nkpt_phys;
        int j;

        /*
         * We are running (mostly) V=P at this point
         *
         * Calculate NKPT - number of kernel page tables.  We have to
         * accomodoate prealloction of the vm_page_array, dump bitmap,
         * MSGBUF_SIZE, and other stuff.  Be generous.
         *
         * Maxmem is in pages.
         *
         * ndmpdp is the number of 1GB pages we wish to map.
         */
        ndmpdp = (ptoa(Maxmem) + NBPDP - 1) >> PDPSHIFT;
        if (ndmpdp < 4)         /* Minimum 4GB of dirmap */
                ndmpdp = 4;
        KKASSERT(ndmpdp <= NKPDPE * NPDEPG);

        /*
         * Starting at the beginning of kvm (not KERNBASE).
         */
        nkpt_phys = (Maxmem * sizeof(struct vm_page) + NBPDR - 1) / NBPDR;
        nkpt_phys += (Maxmem * sizeof(struct pv_entry) + NBPDR - 1) / NBPDR;
        nkpt_phys += ((nkpt + nkpt + 1 + NKPML4E + NKPDPE + NDMPML4E +
                       ndmpdp) + 511) / 512;
        nkpt_phys += 128;

        /*
         * Starting at KERNBASE - map 2G worth of page table pages.
         * KERNBASE is offset -2G from the end of kvm.
         */
        nkpt_base = (NPDPEPG - KPDPI) * NPTEPG; /* typically 2 x 512 */

        /*
         * Allocate pages
         */
        KPTbase = allocpages(firstaddr, nkpt_base);
        KPTphys = allocpages(firstaddr, nkpt_phys);
        KPML4phys = allocpages(firstaddr, 1);
        KPDPphys = allocpages(firstaddr, NKPML4E);
        KPDphys = allocpages(firstaddr, NKPDPE);

        /*
         * Calculate the page directory base for KERNBASE,
         * that is where we start populating the page table pages.
         * Basically this is the end - 2.
         */
        KPDbase = KPDphys + ((NKPDPE - (NPDPEPG - KPDPI)) << PAGE_SHIFT);

        DMPDPphys = allocpages(firstaddr, NDMPML4E);
        if ((amd_feature & AMDID_PAGE1GB) == 0)
                DMPDphys = allocpages(firstaddr, ndmpdp);
        dmaplimit = (vm_paddr_t)ndmpdp << PDPSHIFT;

        /*
         * Fill in the underlying page table pages for the area around
         * KERNBASE.  This remaps low physical memory to KERNBASE.
         *
         * Read-only from zero to physfree
         * XXX not fully used, underneath 2M pages
         */
        for (i = 0; (i << PAGE_SHIFT) < *firstaddr; i++) {
                ((pt_entry_t *)KPTbase)[i] = i << PAGE_SHIFT;
                ((pt_entry_t *)KPTbase)[i] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_G_IDX];
        }

        /*
         * Now map the initial kernel page tables.  One block of page
         * tables is placed at the beginning of kernel virtual memory,
         * and another block is placed at KERNBASE to map the kernel binary,
         * data, bss, and initial pre-allocations.
         */
        for (i = 0; i < nkpt_base; i++) {
                ((pd_entry_t *)KPDbase)[i] = KPTbase + (i << PAGE_SHIFT);
                ((pd_entry_t *)KPDbase)[i] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX];
        }
        for (i = 0; i < nkpt_phys; i++) {
                ((pd_entry_t *)KPDphys)[i] = KPTphys + (i << PAGE_SHIFT);
                ((pd_entry_t *)KPDphys)[i] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX];
        }

        /*
         * Map from zero to end of allocations using 2M pages as an
         * optimization.  This will bypass some of the KPTBase pages
         * above in the KERNBASE area.
         */
        for (i = 0; (i << PDRSHIFT) < *firstaddr; i++) {
                ((pd_entry_t *)KPDbase)[i] = i << PDRSHIFT;
                ((pd_entry_t *)KPDbase)[i] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_PS_IDX] |
                    pmap_bits_default[PG_G_IDX];
        }

        /*
         * And connect up the PD to the PDP.  The kernel pmap is expected
         * to pre-populate all of its PDs.  See NKPDPE in vmparam.h.
         */
        for (i = 0; i < NKPDPE; i++) {
                ((pdp_entry_t *)KPDPphys)[NPDPEPG - NKPDPE + i] =
                                KPDphys + (i << PAGE_SHIFT);
                ((pdp_entry_t *)KPDPphys)[NPDPEPG - NKPDPE + i] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_U_IDX];
        }

        /*
         * Now set up the direct map space using either 2MB or 1GB pages
         * Preset PG_M and PG_A because demotion expects it.
         *
         * When filling in entries in the PD pages make sure any excess
         * entries are set to zero as we allocated enough PD pages
         */
        if ((amd_feature & AMDID_PAGE1GB) == 0) {
                for (i = 0; i < NPDEPG * ndmpdp; i++) {
                        ((pd_entry_t *)DMPDphys)[i] = i << PDRSHIFT;
                        ((pd_entry_t *)DMPDphys)[i] |=
                            pmap_bits_default[PG_RW_IDX] |
                            pmap_bits_default[PG_V_IDX] |
                            pmap_bits_default[PG_PS_IDX] |
                            pmap_bits_default[PG_G_IDX] |
                            pmap_bits_default[PG_M_IDX] |
                            pmap_bits_default[PG_A_IDX];
                }

                /*
                 * And the direct map space's PDP
                 */
                for (i = 0; i < ndmpdp; i++) {
                        ((pdp_entry_t *)DMPDPphys)[i] = DMPDphys +
                                                        (i << PAGE_SHIFT);
                        ((pdp_entry_t *)DMPDPphys)[i] |=
                            pmap_bits_default[PG_RW_IDX] |
                            pmap_bits_default[PG_V_IDX] |
                            pmap_bits_default[PG_U_IDX];
                }
        } else {
                for (i = 0; i < ndmpdp; i++) {
                        ((pdp_entry_t *)DMPDPphys)[i] =
                                                (vm_paddr_t)i << PDPSHIFT;
                        ((pdp_entry_t *)DMPDPphys)[i] |=
                            pmap_bits_default[PG_RW_IDX] |
                            pmap_bits_default[PG_V_IDX] |
                            pmap_bits_default[PG_PS_IDX] |
                            pmap_bits_default[PG_G_IDX] |
                            pmap_bits_default[PG_M_IDX] |
                            pmap_bits_default[PG_A_IDX];
                }
        }

        /* And recursively map PML4 to itself in order to get PTmap */
        ((pdp_entry_t *)KPML4phys)[PML4PML4I] = KPML4phys;
        ((pdp_entry_t *)KPML4phys)[PML4PML4I] |=
            pmap_bits_default[PG_RW_IDX] |
            pmap_bits_default[PG_V_IDX] |
            pmap_bits_default[PG_U_IDX];

        /*
         * Connect the Direct Map slots up to the PML4
         */
        for (j = 0; j < NDMPML4E; ++j) {
                ((pdp_entry_t *)KPML4phys)[DMPML4I + j] =
                    (DMPDPphys + ((vm_paddr_t)j << PML4SHIFT)) |
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_U_IDX];
        }

        /*
         * Connect the KVA slot up to the PML4
         */
        ((pdp_entry_t *)KPML4phys)[KPML4I] = KPDPphys;
        ((pdp_entry_t *)KPML4phys)[KPML4I] |=
            pmap_bits_default[PG_RW_IDX] |
            pmap_bits_default[PG_V_IDX] |
            pmap_bits_default[PG_U_IDX];
}

/*
 *      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;
        int i;

        KvaStart = VM_MIN_KERNEL_ADDRESS;
        KvaEnd = VM_MAX_KERNEL_ADDRESS;
        KvaSize = KvaEnd - KvaStart;

        avail_start = *firstaddr;

        /*
         * Create an initial set of page tables to run the kernel in.
         */
        create_pagetables(firstaddr);

        virtual2_start = KvaStart;
        virtual2_end = PTOV_OFFSET;

        virtual_start = (vm_offset_t) PTOV_OFFSET + *firstaddr;
        virtual_start = pmap_kmem_choose(virtual_start);

        virtual_end = VM_MAX_KERNEL_ADDRESS;

        /* XXX do %cr0 as well */
        load_cr4(rcr4() | CR4_PGE | CR4_PSE);
        load_cr3(KPML4phys);

        /*
         * Initialize protection array.
         */
        i386_protection_init();

        /*
         * The kernel's pmap is statically allocated so we don't have to use
         * pmap_create, which is unlikely to work correctly at this part of
         * the boot sequence (XXX and which no longer exists).
         */
        kernel_pmap.pm_pml4 = (pdp_entry_t *) (PTOV_OFFSET + KPML4phys);
        kernel_pmap.pm_count = 1;
        CPUMASK_ASSALLONES(kernel_pmap.pm_active);
        RB_INIT(&kernel_pmap.pm_pvroot);
        spin_init(&kernel_pmap.pm_spin, "pmapbootstrap");
        for (i = 0; i < PM_PLACEMARKS; ++i)
                kernel_pmap.pm_placemarks[i] = PM_NOPLACEMARK;

        /*
         * 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_start;
        pte = vtopte(va);

        /*
         * CMAP1/CMAP2 are used for zeroing and copying pages.
         */
        SYSMAP(caddr_t, CMAP1, CADDR1, 1)

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

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

        /*
         * msgbufp is used to map the system message buffer.
         * XXX msgbufmap is not used.
         */
        SYSMAP(struct msgbuf *, msgbufmap, msgbufp,
               atop(round_page(MSGBUF_SIZE)))

        virtual_start = va;
        virtual_start = pmap_kmem_choose(virtual_start);

        *CMAP1 = 0;

        /*
         * PG_G is terribly broken on SMP because we IPI invltlb's in some
         * cases rather then invl1pg.  Actually, I don't even know why it
         * works under UP because self-referential page table mappings
         */
//      pgeflag = 0;

/*
 * Initialize the 4MB page size flag
 */
//      pseflag = 0;
/*
 * The 4MB page version of the initial
 * kernel page mapping.
 */
        pdir4mb = 0;

#if !defined(DISABLE_PSE)
        if (cpu_feature & CPUID_PSE) {
                pt_entry_t ptditmp;
                /*
                 * Note that we have enabled PSE mode
                 */
//              pseflag = kernel_pmap.pmap_bits[PG_PS_IDX];
                ptditmp = *(PTmap + x86_64_btop(KERNBASE));
                ptditmp &= ~(NBPDR - 1);
                ptditmp |= pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_PS_IDX] |
                    pmap_bits_default[PG_U_IDX];
//                  pgeflag;
                pdir4mb = ptditmp;
        }
#endif
        cpu_invltlb();

        /* Initialize the PAT MSR */
        pmap_init_pat();
        pmap_pinit_defaults(&kernel_pmap);

        TUNABLE_INT_FETCH("machdep.pmap_fast_kernel_cpusync",
                          &pmap_fast_kernel_cpusync);

}

/*
 * Setup the PAT MSR.
 */
void
pmap_init_pat(void)
{
        uint64_t pat_msr;
        u_long cr0, cr4;

        /*
         * Default values mapping PATi,PCD,PWT bits at system reset.
         * The default values effectively ignore the PATi bit by
         * repeating the encodings for 0-3 in 4-7, and map the PCD
         * and PWT bit combinations to the expected PAT types.
         */
        pat_msr = PAT_VALUE(0, PAT_WRITE_BACK) |        /* 000 */
                  PAT_VALUE(1, PAT_WRITE_THROUGH) |     /* 001 */
                  PAT_VALUE(2, PAT_UNCACHED) |          /* 010 */
                  PAT_VALUE(3, PAT_UNCACHEABLE) |       /* 011 */
                  PAT_VALUE(4, PAT_WRITE_BACK) |        /* 100 */
                  PAT_VALUE(5, PAT_WRITE_THROUGH) |     /* 101 */
                  PAT_VALUE(6, PAT_UNCACHED) |          /* 110 */
                  PAT_VALUE(7, PAT_UNCACHEABLE);        /* 111 */
        pat_pte_index[PAT_WRITE_BACK]   = 0;
        pat_pte_index[PAT_WRITE_THROUGH]= 0         | X86_PG_NC_PWT;
        pat_pte_index[PAT_UNCACHED]     = X86_PG_NC_PCD;
        pat_pte_index[PAT_UNCACHEABLE]  = X86_PG_NC_PCD | X86_PG_NC_PWT;
        pat_pte_index[PAT_WRITE_PROTECTED] = pat_pte_index[PAT_UNCACHEABLE];
        pat_pte_index[PAT_WRITE_COMBINING] = pat_pte_index[PAT_UNCACHEABLE];

        if (cpu_feature & CPUID_PAT) {
                /*
                 * If we support the PAT then set-up entries for
                 * WRITE_PROTECTED and WRITE_COMBINING using bit patterns
                 * 5 and 6.
                 */
                pat_msr = (pat_msr & ~PAT_MASK(5)) |
                          PAT_VALUE(5, PAT_WRITE_PROTECTED);
                pat_msr = (pat_msr & ~PAT_MASK(6)) |
                          PAT_VALUE(6, PAT_WRITE_COMBINING);
                pat_pte_index[PAT_WRITE_PROTECTED] = X86_PG_PTE_PAT | X86_PG_NC_PWT;
                pat_pte_index[PAT_WRITE_COMBINING] = X86_PG_PTE_PAT | X86_PG_NC_PCD;

                /*
                 * Then enable the PAT
                 */

                /* Disable PGE. */
                cr4 = rcr4();
                load_cr4(cr4 & ~CR4_PGE);

                /* Disable caches (CD = 1, NW = 0). */
                cr0 = rcr0();
                load_cr0((cr0 & ~CR0_NW) | CR0_CD);

                /* Flushes caches and TLBs. */
                wbinvd();
                cpu_invltlb();

                /* Update PAT and index table. */
                wrmsr(MSR_PAT, pat_msr);

                /* Flush caches and TLBs again. */
                wbinvd();
                cpu_invltlb();

                /* Restore caches and PGE. */
                load_cr0(cr0);
                load_cr4(cr4);
                PatMsr = pat_msr;
        }
}

/*
 * Set 4mb pdir for mp startup
 */
void
pmap_set_opt(void)
{
        if (cpu_feature & CPUID_PSE) {
                load_cr4(rcr4() | CR4_PSE);
                if (pdir4mb && mycpu->gd_cpuid == 0) {  /* only on BSP */
                        cpu_invltlb();
                }
        }
}

/*
 *      Initialize the pmap module.
 *      Called by vm_init, to initialize any structures that the pmap
 *      system needs to map virtual memory.
 *      pmap_init has been enhanced to support in a fairly consistant
 *      way, discontiguous physical memory.
 */
void
pmap_init(void)
{
        int i;
        int initial_pvs;

        /*
         * Allocate memory for random pmap data structures.  Includes the
         * pv_head_table.
         */

        for (i = 0; i < vm_page_array_size; i++) {
                vm_page_t m;

                m = &vm_page_array[i];
                TAILQ_INIT(&m->md.pv_list);
        }

        /*
         * init the pv free list
         */
        initial_pvs = vm_page_array_size;
        if (initial_pvs < MINPV)
                initial_pvs = MINPV;
        pvzone = &pvzone_store;
        pvinit = (void *)kmem_alloc(&kernel_map,
                                    initial_pvs * sizeof (struct pv_entry),
                                    VM_SUBSYS_PVENTRY);
        zbootinit(pvzone, "PV ENTRY", sizeof (struct pv_entry),
                  pvinit, initial_pvs);

        /*
         * Now it is safe to enable pv_table recording.
         */
        pmap_initialized = TRUE;
}

/*
 * 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.
 */
void
pmap_init2(void)
{
        int shpgperproc = PMAP_SHPGPERPROC;
        int entry_max;

        TUNABLE_INT_FETCH("vm.pmap.shpgperproc", &shpgperproc);
        pv_entry_max = shpgperproc * maxproc + vm_page_array_size;
        TUNABLE_INT_FETCH("vm.pmap.pv_entries", &pv_entry_max);
        pv_entry_high_water = 9 * (pv_entry_max / 10);

        /*
         * Subtract out pages already installed in the zone (hack)
         */
        entry_max = pv_entry_max - vm_page_array_size;
        if (entry_max <= 0)
                entry_max = 1;

        zinitna(pvzone, NULL, 0, entry_max, ZONE_INTERRUPT);

        /*
         * Enable dynamic deletion of empty higher-level page table pages
         * by default only if system memory is < 8GB (use 7GB for slop).
         * This can save a little memory, but imposes significant
         * performance overhead for things like bulk builds, and for programs
         * which do a lot of memory mapping and memory unmapping.
         */
        if (pmap_dynamic_delete < 0) {
                if (vmstats.v_page_count < 7LL * 1024 * 1024 * 1024 / PAGE_SIZE)
                        pmap_dynamic_delete = 1;
                else
                        pmap_dynamic_delete = 0;
        }
}

/*
 * Typically used to initialize a fictitious page by vm/device_pager.c
 */
void
pmap_page_init(struct vm_page *m)
{
        vm_page_init(m);
        TAILQ_INIT(&m->md.pv_list);
}

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

/*
 * this routine defines the region(s) of memory that should
 * not be tested for the modified bit.
 */
static __inline
int
pmap_track_modified(vm_pindex_t pindex)
{
        vm_offset_t va = (vm_offset_t)pindex << PAGE_SHIFT;
        if ((va < clean_sva) || (va >= clean_eva)) 
                return 1;
        else
                return 0;
}

/*
 * Extract the physical page address associated with the map/VA pair.
 * The page must be wired for this to work reliably.
 */
vm_paddr_t 
pmap_extract(pmap_t pmap, vm_offset_t va, void **handlep)
{
        vm_paddr_t rtval;
        pv_entry_t pt_pv;
        pt_entry_t *ptep;

        rtval = 0;
        if (va >= VM_MAX_USER_ADDRESS) {
                /*
                 * Kernel page directories might be direct-mapped and
                 * there is typically no PV tracking of pte's
                 */
                pd_entry_t *pt;

                pt = pmap_pt(pmap, va);
                if (pt && (*pt & pmap->pmap_bits[PG_V_IDX])) {
                        if (*pt & pmap->pmap_bits[PG_PS_IDX]) {
                                rtval = *pt & PG_PS_FRAME;
                                rtval |= va & PDRMASK;
                        } else {
                                ptep = pmap_pt_to_pte(*pt, va);
                                if (*pt & pmap->pmap_bits[PG_V_IDX]) {
                                        rtval = *ptep & PG_FRAME;
                                        rtval |= va & PAGE_MASK;
                                }
                        }
                }
                if (handlep)
                        *handlep = NULL;
        } else {
                /*
                 * User pages currently do not direct-map the page directory
                 * and some pages might not used managed PVs.  But all PT's
                 * will have a PV.
                 */
                pt_pv = pv_get(pmap, pmap_pt_pindex(va), NULL);
                if (pt_pv) {
                        ptep = pv_pte_lookup(pt_pv, pmap_pte_index(va));
                        if (*ptep & pmap->pmap_bits[PG_V_IDX]) {
                                rtval = *ptep & PG_FRAME;
                                rtval |= va & PAGE_MASK;
                        }
                        if (handlep)
                                *handlep = pt_pv;       /* locked until done */
                        else
                                pv_put (pt_pv);
                } else if (handlep) {
                        *handlep = NULL;
                }
        }
        return rtval;
}

void
pmap_extract_done(void *handle)
{
        if (handle)
                pv_put((pv_entry_t)handle);
}

/*
 * Similar to extract but checks protections, SMP-friendly short-cut for
 * vm_fault_page[_quick]().  Can return NULL to cause the caller to
 * fall-through to the real fault code.  Does not work with HVM page
 * tables.
 *
 * if busyp is NULL the returned page, if not NULL, is held (and not busied).
 *
 * If busyp is not NULL and this function sets *busyp non-zero, the returned
 * page is busied (and not held).
 *
 * If busyp is not NULL and this function sets *busyp to zero, the returned
 * page is held (and not busied).
 *
 * If VM_PROT_WRITE or VM_PROT_OVERRIDE_WRITE is set in prot, and the pte
 * is already writable, the returned page will be dirtied.  If the pte
 * is not already writable NULL is returned.  In otherwords, if either
 * bit is set and a vm_page_t is returned, any COW will already have happened
 * and that page can be written by the caller.
 *
 * WARNING! THE RETURNED PAGE IS ONLY HELD AND NOT SUITABLE FOR READING
 *          OR WRITING AS-IS.
 */
vm_page_t
pmap_fault_page_quick(pmap_t pmap, vm_offset_t va, vm_prot_t prot, int *busyp)
{
        if (pmap &&
            va < VM_MAX_USER_ADDRESS &&
            (pmap->pm_flags & PMAP_HVM) == 0) {
                pv_entry_t pt_pv;
                pv_entry_t pte_pv;
                pt_entry_t *ptep;
                pt_entry_t req;
                vm_page_t m;
                int error;

                req = pmap->pmap_bits[PG_V_IDX] |
                      pmap->pmap_bits[PG_U_IDX];
                if (prot & (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE))
                        req |= pmap->pmap_bits[PG_RW_IDX];

                pt_pv = pv_get(pmap, pmap_pt_pindex(va), NULL);
                if (pt_pv == NULL)
                        return (NULL);
                ptep = pv_pte_lookup(pt_pv, pmap_pte_index(va));
                if ((*ptep & req) != req) {
                        pv_put(pt_pv);
                        return (NULL);
                }
                pte_pv = pv_get_try(pmap, pmap_pte_pindex(va), NULL, &error);
                if (pte_pv && error == 0) {
                        m = pte_pv->pv_m;
                        if (prot & (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE)) {
                                /* interlocked by presence of pv_entry */
                                vm_page_dirty(m);
                        }
                        if (busyp) {
                                if (prot & VM_PROT_WRITE) {
                                        if (vm_page_busy_try(m, TRUE))
                                                m = NULL;
                                        *busyp = 1;
                                } else {
                                        vm_page_hold(m);
                                        *busyp = 0;
                                }
                        } else {
                                vm_page_hold(m);
                        }
                        pv_put(pte_pv);
                } else if (pte_pv) {
                        pv_drop(pte_pv);
                        m = NULL;
                } else {
                        /* error, since we didn't request a placemarker */
                        m = NULL;
                }
                pv_put(pt_pv);
                return(m);
        } else {
                return(NULL);
        }
}

/*
 * Extract the physical page address associated kernel virtual address.
 */
vm_paddr_t
pmap_kextract(vm_offset_t va)
{
        pd_entry_t pt;          /* pt entry in pd */
        vm_paddr_t pa;

        if (va >= DMAP_MIN_ADDRESS && va < DMAP_MAX_ADDRESS) {
                pa = DMAP_TO_PHYS(va);
        } else {
                pt = *vtopt(va);
                if (pt & kernel_pmap.pmap_bits[PG_PS_IDX]) {
                        pa = (pt & PG_PS_FRAME) | (va & PDRMASK);
                } else {
                        /*
                         * Beware of a concurrent promotion that changes the
                         * PDE at this point!  For example, vtopte() must not
                         * be used to access the PTE because it would use the
                         * new PDE.  It is, however, safe to use the old PDE
                         * because the page table page is preserved by the
                         * promotion.
                         */
                        pa = *pmap_pt_to_pte(pt, va);
                        pa = (pa & PG_FRAME) | (va & PAGE_MASK);
                }
        }
        return pa;
}

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

/*
 * Routine: pmap_kenter
 * Function:
 *      Add a wired page to the KVA
 *      NOTE! note that in order for the mapping to take effect -- you
 *      should do an invltlb after doing the pmap_kenter().
 */
void 
pmap_kenter(vm_offset_t va, vm_paddr_t pa)
{
        pt_entry_t *ptep;
        pt_entry_t npte;

        npte = pa |
               kernel_pmap.pmap_bits[PG_RW_IDX] |
               kernel_pmap.pmap_bits[PG_V_IDX];
//             pgeflag;
        ptep = vtopte(va);
#if 1
        pmap_inval_smp(&kernel_pmap, va, 1, ptep, npte);
#else
        /* FUTURE */
        if (*ptep)
                pmap_inval_smp(&kernel_pmap, va, ptep, npte);
        else
                *ptep = npte;
#endif
}

/*
 * Similar to pmap_kenter(), except we only invalidate the mapping on the
 * current CPU.  Returns 0 if the previous pte was 0, 1 if it wasn't
 * (caller can conditionalize calling smp_invltlb()).
 */
int
pmap_kenter_quick(vm_offset_t va, vm_paddr_t pa)
{
        pt_entry_t *ptep;
        pt_entry_t npte;
        int res;

        npte = pa | kernel_pmap.pmap_bits[PG_RW_IDX] |
                    kernel_pmap.pmap_bits[PG_V_IDX];
        // npte |= pgeflag;
        ptep = vtopte(va);
#if 1
        res = 1;
#else
        /* FUTURE */
        res = (*ptep != 0);
#endif
        atomic_swap_long(ptep, npte);
        cpu_invlpg((void *)va);

        return res;
}

/*
 * Enter addresses into the kernel pmap but don't bother
 * doing any tlb invalidations.  Caller will do a rollup
 * invalidation via pmap_rollup_inval().
 */
int
pmap_kenter_noinval(vm_offset_t va, vm_paddr_t pa)
{
        pt_entry_t *ptep;
        pt_entry_t npte;
        int res;

        npte = pa |
            kernel_pmap.pmap_bits[PG_RW_IDX] |
            kernel_pmap.pmap_bits[PG_V_IDX];
//          pgeflag;
        ptep = vtopte(va);
#if 1
        res = 1;
#else
        /* FUTURE */
        res = (*ptep != 0);
#endif
        atomic_swap_long(ptep, npte);
        cpu_invlpg((void *)va);

        return res;
}

/*
 * remove a page from the kernel pagetables
 */
void
pmap_kremove(vm_offset_t va)
{
        pt_entry_t *ptep;

        ptep = vtopte(va);
        pmap_inval_smp(&kernel_pmap, va, 1, ptep, 0);
}

void
pmap_kremove_quick(vm_offset_t va)
{
        pt_entry_t *ptep;

        ptep = vtopte(va);
        (void)pte_load_clear(ptep);
        cpu_invlpg((void *)va);
}

/*
 * Remove addresses from the kernel pmap but don't bother
 * doing any tlb invalidations.  Caller will do a rollup
 * invalidation via pmap_rollup_inval().
 */
void
pmap_kremove_noinval(vm_offset_t va)
{
        pt_entry_t *ptep;

        ptep = vtopte(va);
        (void)pte_load_clear(ptep);
}

/*
 * XXX these need to be recoded.  They are not used in any critical path.
 */
void
pmap_kmodify_rw(vm_offset_t va)
{
        atomic_set_long(vtopte(va), kernel_pmap.pmap_bits[PG_RW_IDX]);
        cpu_invlpg((void *)va);
}

/* NOT USED
void
pmap_kmodify_nc(vm_offset_t va)
{
        atomic_set_long(vtopte(va), PG_N);
        cpu_invlpg((void *)va);
}
*/

/*
 * Used to map a range of physical addresses into kernel virtual
 * address space during the low level boot, typically to map the
 * dump bitmap, message buffer, and vm_page_array.
 *
 * These mappings are typically made at some pointer after the end of the
 * kernel text+data.
 *
 * We could return PHYS_TO_DMAP(start) here and not allocate any
 * via (*virtp), but then kmem from userland and kernel dumps won't
 * have access to the related pointers.
 */
vm_offset_t
pmap_map(vm_offset_t *virtp, vm_paddr_t start, vm_paddr_t end, int prot)
{
        vm_offset_t va;
        vm_offset_t va_start;

        /*return PHYS_TO_DMAP(start);*/

        va_start = *virtp;
        va = va_start;

        while (start < end) {
                pmap_kenter_quick(va, start);
                va += PAGE_SIZE;
                start += PAGE_SIZE;
        }
        *virtp = va;
        return va_start;
}

#define PMAP_CLFLUSH_THRESHOLD  (2 * 1024 * 1024)

/*
 * Remove the specified set of pages from the data and instruction caches.
 *
 * In contrast to pmap_invalidate_cache_range(), this function does not
 * rely on the CPU's self-snoop feature, because it is intended for use
 * when moving pages into a different cache domain.
 */
void
pmap_invalidate_cache_pages(vm_page_t *pages, int count)
{
        vm_offset_t daddr, eva;
        int i;

        if (count >= PMAP_CLFLUSH_THRESHOLD / PAGE_SIZE ||
            (cpu_feature & CPUID_CLFSH) == 0)
                wbinvd();
        else {
                cpu_mfence();
                for (i = 0; i < count; i++) {
                        daddr = PHYS_TO_DMAP(VM_PAGE_TO_PHYS(pages[i]));
                        eva = daddr + PAGE_SIZE;
                        for (; daddr < eva; daddr += cpu_clflush_line_size)
                                clflush(daddr);
                }
                cpu_mfence();
        }
}

void
pmap_invalidate_cache_range(vm_offset_t sva, vm_offset_t eva)
{
        KASSERT((sva & PAGE_MASK) == 0,
            ("pmap_invalidate_cache_range: sva not page-aligned"));
        KASSERT((eva & PAGE_MASK) == 0,
            ("pmap_invalidate_cache_range: eva not page-aligned"));

        if (cpu_feature & CPUID_SS) {
                ; /* If "Self Snoop" is supported, do nothing. */
        } else {
                /* Globally invalidate caches */
                cpu_wbinvd_on_all_cpus();
        }
}

/*
 * Invalidate the specified range of virtual memory on all cpus associated
 * with the pmap.
 */
void
pmap_invalidate_range(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
{
        pmap_inval_smp(pmap, sva, (eva - sva) >> PAGE_SHIFT, NULL, 0);
}

/*
 * Add a list of wired pages to the kva.  This routine is used for temporary
 * kernel mappings such as those found in buffer cache buffer.  Page
 * modifications and accesses are not tracked or recorded.
 *
 * NOTE! Old mappings are simply overwritten, and we cannot assume relaxed
 *       semantics as previous mappings may have been zerod without any
 *       invalidation.
 *
 * The page *must* be wired.
 */
static __inline void
_pmap_qenter(vm_offset_t beg_va, vm_page_t *m, int count, int doinval)
{
        vm_offset_t end_va;
        vm_offset_t va;

        end_va = beg_va + count * PAGE_SIZE;

        for (va = beg_va; va < end_va; va += PAGE_SIZE) {
                pt_entry_t pte;
                pt_entry_t *ptep;

                ptep = vtopte(va);
                pte = VM_PAGE_TO_PHYS(*m) |
                        kernel_pmap.pmap_bits[PG_RW_IDX] |
                        kernel_pmap.pmap_bits[PG_V_IDX] |
                        kernel_pmap.pmap_cache_bits[(*m)->pat_mode];
//              pgeflag;
                atomic_swap_long(ptep, pte);
                m++;
        }
        if (doinval)
                pmap_invalidate_range(&kernel_pmap, beg_va, end_va);
}

void
pmap_qenter(vm_offset_t beg_va, vm_page_t *m, int count)
{
        _pmap_qenter(beg_va, m, count, 1);
}

void
pmap_qenter_noinval(vm_offset_t beg_va, vm_page_t *m, int count)
{
        _pmap_qenter(beg_va, m, count, 0);
}

/*
 * This routine jerks page mappings from the kernel -- it is meant only
 * for temporary mappings such as those found in buffer cache buffers.
 * No recording modified or access status occurs.
 *
 * MPSAFE, INTERRUPT SAFE (cluster callback)
 */
void
pmap_qremove(vm_offset_t beg_va, int count)
{
        vm_offset_t end_va;
        vm_offset_t va;

        end_va = beg_va + count * PAGE_SIZE;

        for (va = beg_va; va < end_va; va += PAGE_SIZE) {
                pt_entry_t *pte;

                pte = vtopte(va);
                (void)pte_load_clear(pte);
                cpu_invlpg((void *)va);
        }
        pmap_invalidate_range(&kernel_pmap, beg_va, end_va);
}

/*
 * This routine removes temporary kernel mappings, only invalidating them
 * on the current cpu.  It should only be used under carefully controlled
 * conditions.
 */
void
pmap_qremove_quick(vm_offset_t beg_va, int count)
{
        vm_offset_t end_va;
        vm_offset_t va;

        end_va = beg_va + count * PAGE_SIZE;

        for (va = beg_va; va < end_va; va += PAGE_SIZE) {
                pt_entry_t *pte;

                pte = vtopte(va);
                (void)pte_load_clear(pte);
                cpu_invlpg((void *)va);
        }
}

/*
 * This routine removes temporary kernel mappings *without* invalidating
 * the TLB.  It can only be used on permanent kva reservations such as those
 * found in buffer cache buffers, under carefully controlled circumstances.
 *
 * NOTE: Repopulating these KVAs requires unconditional invalidation.
 *       (pmap_qenter() does unconditional invalidation).
 */
void
pmap_qremove_noinval(vm_offset_t beg_va, int count)
{
        vm_offset_t end_va;
        vm_offset_t va;

        end_va = beg_va + count * PAGE_SIZE;

        for (va = beg_va; va < end_va; va += PAGE_SIZE) {
                pt_entry_t *pte;

                pte = vtopte(va);
                (void)pte_load_clear(pte);
        }
}

/*
 * Create a new thread and optionally associate it with a (new) process.
 * NOTE! the new thread's cpu may not equal the current cpu.
 */
void
pmap_init_thread(thread_t td)
{
        /* enforce pcb placement & alignment */
        td->td_pcb = (struct pcb *)(td->td_kstack + td->td_kstack_size) - 1;
        td->td_pcb = (struct pcb *)((intptr_t)td->td_pcb & ~(intptr_t)0xF);
        td->td_savefpu = &td->td_pcb->pcb_save;
        td->td_sp = (char *)td->td_pcb; /* no -16 */
}

/*
 * This routine directly affects the fork perf for a process.
 */
void
pmap_init_proc(struct proc *p)
{
}

static void
pmap_pinit_defaults(struct pmap *pmap)
{
        bcopy(pmap_bits_default, pmap->pmap_bits,
              sizeof(pmap_bits_default));
        bcopy(protection_codes, pmap->protection_codes,
              sizeof(protection_codes));
        bcopy(pat_pte_index, pmap->pmap_cache_bits,
              sizeof(pat_pte_index));
        pmap->pmap_cache_mask = X86_PG_NC_PWT | X86_PG_NC_PCD | X86_PG_PTE_PAT;
        pmap->copyinstr = std_copyinstr;
        pmap->copyin = std_copyin;
        pmap->copyout = std_copyout;
        pmap->fubyte = std_fubyte;
        pmap->subyte = std_subyte;
        pmap->fuword32 = std_fuword32;
        pmap->fuword64 = std_fuword64;
        pmap->suword32 = std_suword32;
        pmap->suword64 = std_suword64;
        pmap->swapu32 = std_swapu32;
        pmap->swapu64 = std_swapu64;
}
/*
 * Initialize pmap0/vmspace0.
 *
 * On architectures where the kernel pmap is not integrated into the user
 * process pmap, this pmap represents the process pmap, not the kernel pmap.
 * kernel_pmap should be used to directly access the kernel_pmap.
 */
void
pmap_pinit0(struct pmap *pmap)
{
        int i;

        pmap->pm_pml4 = (pml4_entry_t *)(PTOV_OFFSET + KPML4phys);
        pmap->pm_count = 1;
        CPUMASK_ASSZERO(pmap->pm_active);
        pmap->pm_pvhint = NULL;
        RB_INIT(&pmap->pm_pvroot);
        spin_init(&pmap->pm_spin, "pmapinit0");
        for (i = 0; i < PM_PLACEMARKS; ++i)
                pmap->pm_placemarks[i] = PM_NOPLACEMARK;
        bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
        pmap_pinit_defaults(pmap);
}

/*
 * Initialize a preallocated and zeroed pmap structure,
 * such as one in a vmspace structure.
 */
static void
pmap_pinit_simple(struct pmap *pmap)
{
        int i;

        /*
         * Misc initialization
         */
        pmap->pm_count = 1;
        CPUMASK_ASSZERO(pmap->pm_active);
        pmap->pm_pvhint = NULL;
        pmap->pm_flags = PMAP_FLAG_SIMPLE;

        pmap_pinit_defaults(pmap);

        /*
         * Don't blow up locks/tokens on re-use (XXX fix/use drop code
         * for this).
         */
        if (pmap->pm_pmlpv == NULL) {
                RB_INIT(&pmap->pm_pvroot);
                bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
                spin_init(&pmap->pm_spin, "pmapinitsimple");
                for (i = 0; i < PM_PLACEMARKS; ++i)
                        pmap->pm_placemarks[i] = PM_NOPLACEMARK;
        }
}

void
pmap_pinit(struct pmap *pmap)
{
        pv_entry_t pv;
        int j;

        if (pmap->pm_pmlpv) {
                if (pmap->pmap_bits[TYPE_IDX] != REGULAR_PMAP) {
                        pmap_puninit(pmap);
                }
        }

        pmap_pinit_simple(pmap);
        pmap->pm_flags &= ~PMAP_FLAG_SIMPLE;

        /*
         * No need to allocate page table space yet but we do need a valid
         * page directory table.
         */
        if (pmap->pm_pml4 == NULL) {
                pmap->pm_pml4 =
                    (pml4_entry_t *)kmem_alloc_pageable(&kernel_map,
                                                        PAGE_SIZE,
                                                        VM_SUBSYS_PML4);
        }

        /*
         * Allocate the page directory page, which wires it even though
         * it isn't being entered into some higher level page table (it
         * being the highest level).  If one is already cached we don't
         * have to do anything.
         */
        if ((pv = pmap->pm_pmlpv) == NULL) {
                pv = pmap_allocpte(pmap, pmap_pml4_pindex(), NULL);
                pmap->pm_pmlpv = pv;
                pmap_kenter((vm_offset_t)pmap->pm_pml4,
                            VM_PAGE_TO_PHYS(pv->pv_m));
                pv_put(pv);

                /*
                 * Install DMAP and KMAP.
                 */
                for (j = 0; j < NDMPML4E; ++j) {
                        pmap->pm_pml4[DMPML4I + j] =
                            (DMPDPphys + ((vm_paddr_t)j << PML4SHIFT)) |
                            pmap->pmap_bits[PG_RW_IDX] |
                            pmap->pmap_bits[PG_V_IDX] |
                            pmap->pmap_bits[PG_U_IDX];
                }
                pmap->pm_pml4[KPML4I] = KPDPphys |
                    pmap->pmap_bits[PG_RW_IDX] |
                    pmap->pmap_bits[PG_V_IDX] |
                    pmap->pmap_bits[PG_U_IDX];

                /*
                 * install self-referential address mapping entry
                 */
                pmap->pm_pml4[PML4PML4I] = VM_PAGE_TO_PHYS(pv->pv_m) |
                    pmap->pmap_bits[PG_V_IDX] |
                    pmap->pmap_bits[PG_RW_IDX] |
                    pmap->pmap_bits[PG_A_IDX] |
                    pmap->pmap_bits[PG_M_IDX];
        } else {
                KKASSERT(pv->pv_m->flags & PG_MAPPED);
                KKASSERT(pv->pv_m->flags & PG_WRITEABLE);
        }
        KKASSERT(pmap->pm_pml4[255] == 0);
        KKASSERT(RB_ROOT(&pmap->pm_pvroot) == pv);
        KKASSERT(pv->pv_entry.rbe_left == NULL);
        KKASSERT(pv->pv_entry.rbe_right == NULL);
}

/*
 * Clean up a pmap structure so it can be physically freed.  This routine
 * is called by the vmspace dtor function.  A great deal of pmap data is
 * left passively mapped to improve vmspace management so we have a bit
 * of cleanup work to do here.
 */
void
pmap_puninit(pmap_t pmap)
{
        pv_entry_t pv;
        vm_page_t p;

        KKASSERT(CPUMASK_TESTZERO(pmap->pm_active));
        if ((pv = pmap->pm_pmlpv) != NULL) {
                if (pv_hold_try(pv) == 0)
                        pv_lock(pv);
                KKASSERT(pv == pmap->pm_pmlpv);
                p = pmap_remove_pv_page(pv);
                pv_free(pv, NULL);
                pv = NULL;      /* safety */
                pmap_kremove((vm_offset_t)pmap->pm_pml4);
                vm_page_busy_wait(p, FALSE, "pgpun");
                KKASSERT(p->flags & (PG_FICTITIOUS|PG_UNMANAGED));
                vm_page_unwire(p, 0);
                vm_page_flag_clear(p, PG_MAPPED | PG_WRITEABLE);

                /*
                 * XXX eventually clean out PML4 static entries and
                 * use vm_page_free_zero()
                 */
                vm_page_free(p);
                pmap->pm_pmlpv = NULL;
        }
        if (pmap->pm_pml4) {
                KKASSERT(pmap->pm_pml4 != (void *)(PTOV_OFFSET + KPML4phys));
                kmem_free(&kernel_map, (vm_offset_t)pmap->pm_pml4, PAGE_SIZE);
                pmap->pm_pml4 = NULL;
        }
        KKASSERT(pmap->pm_stats.resident_count == 0);
        KKASSERT(pmap->pm_stats.wired_count == 0);
}

/*
 * This function is now unused (used to add the pmap to the pmap_list)
 */
void
pmap_pinit2(struct pmap *pmap)
{
}

/*
 * This routine is called when various levels in the page table need to
 * be populated.  This routine cannot fail.
 *
 * This function returns two locked pv_entry's, one representing the
 * requested pv and one representing the requested pv's parent pv.  If
 * an intermediate page table does not exist it will be created, mapped,
 * wired, and the parent page table will be given an additional hold
 * count representing the presence of the child pv_entry.
 */
static
pv_entry_t
pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex, pv_entry_t *pvpp)
{
        pt_entry_t *ptep;
        pv_entry_t pv;
        pv_entry_t pvp;
        pt_entry_t v;
        vm_pindex_t pt_pindex;
        vm_page_t m;
        int isnew;
        int ispt;

        /*
         * If the pv already exists and we aren't being asked for the
         * parent page table page we can just return it.  A locked+held pv
         * is returned.  The pv will also have a second hold related to the
         * pmap association that we don't have to worry about.
         */
        ispt = 0;
        pv = pv_alloc(pmap, ptepindex, &isnew);
        if (isnew == 0 && pvpp == NULL)
                return(pv);

        /*
         * Special case terminal PVs.  These are not page table pages so
         * no vm_page is allocated (the caller supplied the vm_page).  If
         * pvpp is non-NULL we are being asked to also removed the pt_pv
         * for this pv.
         *
         * Note that pt_pv's are only returned for user VAs. We assert that
         * a pt_pv is not being requested for kernel VAs.  The kernel
         * pre-wires all higher-level page tables so don't overload managed
         * higher-level page tables on top of it!
         */
        if (ptepindex < pmap_pt_pindex(0)) {
                if (ptepindex >= NUPTE_USER) {
                        /* kernel manages this manually for KVM */
                        KKASSERT(pvpp == NULL);
                } else {
                        KKASSERT(pvpp != NULL);
                        pt_pindex = NUPTE_TOTAL + (ptepindex >> NPTEPGSHIFT);
                        pvp = pmap_allocpte(pmap, pt_pindex, NULL);
                        if (isnew)
                                vm_page_wire_quick(pvp->pv_m);
                        *pvpp = pvp;
                }
                return(pv);
        }

        /*
         * The kernel never uses managed PT/PD/PDP pages.
         */
        KKASSERT(pmap != &kernel_pmap);

        /*
         * Non-terminal PVs allocate a VM page to represent the page table,
         * so we have to resolve pvp and calculate ptepindex for the pvp
         * and then for the page table entry index in the pvp for
         * fall-through.
         */
        if (ptepindex < pmap_pd_pindex(0)) {
                /*
                 * pv is PT, pvp is PD
                 */
                ptepindex = (ptepindex - pmap_pt_pindex(0)) >> NPDEPGSHIFT;
                ptepindex += NUPTE_TOTAL + NUPT_TOTAL;
                pvp = pmap_allocpte(pmap, ptepindex, NULL);

                /*
                 * PT index in PD
                 */
                ptepindex = pv->pv_pindex - pmap_pt_pindex(0);
                ptepindex &= ((1ul << NPDEPGSHIFT) - 1);
                ispt = 1;
        } else if (ptepindex < pmap_pdp_pindex(0)) {
                /*
                 * pv is PD, pvp is PDP
                 *
                 * SIMPLE PMAP NOTE: Simple pmaps do not allocate above
                 *                   the PD.
                 */
                ptepindex = (ptepindex - pmap_pd_pindex(0)) >> NPDPEPGSHIFT;
                ptepindex += NUPTE_TOTAL + NUPT_TOTAL + NUPD_TOTAL;

                if (pmap->pm_flags & PMAP_FLAG_SIMPLE) {
                        KKASSERT(pvpp == NULL);
                        pvp = NULL;
                } else {
                        pvp = pmap_allocpte(pmap, ptepindex, NULL);
                }

                /*
                 * PD index in PDP
                 */
                ptepindex = pv->pv_pindex - pmap_pd_pindex(0);
                ptepindex &= ((1ul << NPDPEPGSHIFT) - 1);
        } else if (ptepindex < pmap_pml4_pindex()) {
                /*
                 * pv is PDP, pvp is the root pml4 table
                 */
                pvp = pmap_allocpte(pmap, pmap_pml4_pindex(), NULL);

                /*
                 * PDP index in PML4
                 */
                ptepindex = pv->pv_pindex - pmap_pdp_pindex(0);
                ptepindex &= ((1ul << NPML4EPGSHIFT) - 1);
        } else {
                /*
                 * pv represents the top-level PML4, there is no parent.
                 */
                pvp = NULL;
        }

        if (isnew == 0)
                goto notnew;

        /*
         * (isnew) is TRUE, pv is not terminal.
         *
         * (1) Add a wire count to the parent page table (pvp).
         * (2) Allocate a VM page for the page table.
         * (3) Enter the VM page into the parent page table.
         *
         * page table pages are marked PG_WRITEABLE and PG_MAPPED.
         */
        if (pvp)
                vm_page_wire_quick(pvp->pv_m);

        for (;;) {
                m = vm_page_alloc(NULL, pv->pv_pindex,
                                  VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM |
                                  VM_ALLOC_INTERRUPT);
                if (m)
                        break;
                vm_wait(0);
        }
        vm_page_wire(m);        /* wire for mapping in parent */
        vm_page_unmanage(m);    /* m must be spinunlocked */
        pmap_zero_page(VM_PAGE_TO_PHYS(m));
        m->valid = VM_PAGE_BITS_ALL;

        vm_page_spin_lock(m);
        pmap_page_stats_adding(m);
        TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
        pv->pv_m = m;
        vm_page_flag_set(m, PG_MAPPED | PG_WRITEABLE);
        vm_page_spin_unlock(m);

        /*
         * (isnew) is TRUE, pv is not terminal.
         *
         * Wire the page into pvp.  Bump the resident_count for the pmap.
         * There is no pvp for the top level, address the pm_pml4[] array
         * directly.
         *
         * If the caller wants the parent we return it, otherwise
         * we just put it away.
         *
         * No interlock is needed for pte 0 -> non-zero.
         *
         * In the situation where *ptep is valid we might have an unmanaged
         * page table page shared from another page table which we need to
         * unshare before installing our private page table page.
         */
        if (pvp) {
                v = VM_PAGE_TO_PHYS(m) |
                    (pmap->pmap_bits[PG_U_IDX] |
                     pmap->pmap_bits[PG_RW_IDX] |
                     pmap->pmap_bits[PG_V_IDX] |
                     pmap->pmap_bits[PG_A_IDX] |
                     pmap->pmap_bits[PG_M_IDX]);
                ptep = pv_pte_lookup(pvp, ptepindex);
                if (*ptep & pmap->pmap_bits[PG_V_IDX]) {
                        pt_entry_t pte;

                        if (ispt == 0) {
                                panic("pmap_allocpte: unexpected pte %p/%d",
                                      pvp, (int)ptepindex);
                        }
                        pte = pmap_inval_smp(pmap, (vm_offset_t)-1, 1, ptep, v);
                        if (vm_page_unwire_quick(
                                        PHYS_TO_VM_PAGE(pte & PG_FRAME))) {
                                panic("pmap_allocpte: shared pgtable "
                                      "pg bad wirecount");
                        }
                } else {
                        pt_entry_t pte;

                        pte = atomic_swap_long(ptep, v);
                        if (pte != 0) {
                                kprintf("install pgtbl mixup 0x%016jx "
                                        "old/new 0x%016jx/0x%016jx\n",
                                        (intmax_t)ptepindex, pte, v);
                        }
                }
        }
        vm_page_wakeup(m);

        /*
         * (isnew) may be TRUE or FALSE, pv may or may not be terminal.
         */
notnew:
        if (pvp) {
                KKASSERT(pvp->pv_m != NULL);
                ptep = pv_pte_lookup(pvp, ptepindex);
                v = VM_PAGE_TO_PHYS(pv->pv_m) |
                    (pmap->pmap_bits[PG_U_IDX] |
                     pmap->pmap_bits[PG_RW_IDX] |
                     pmap->pmap_bits[PG_V_IDX] |
                     pmap->pmap_bits[PG_A_IDX] |
                     pmap->pmap_bits[PG_M_IDX]);
                if (*ptep != v) {
                        kprintf("mismatched upper level pt %016jx/%016jx\n",
                                *ptep, v);
                }
        }
        if (pvpp)
                *pvpp = pvp;
        else if (pvp)
                pv_put(pvp);
        return (pv);
}

/*
 * This version of pmap_allocpte() checks for possible segment optimizations
 * that would allow page-table sharing.  It can be called for terminal
 * page or page table page ptepindex's.
 *
 * The function is called with page table page ptepindex's for fictitious
 * and unmanaged terminal pages.  That is, we don't want to allocate a
 * terminal pv, we just want the pt_pv.  pvpp is usually passed as NULL
 * for this case.
 *
 * This function can return a pv and *pvpp associated with the passed in pmap
 * OR a pv and *pvpp associated with the shared pmap.  In the latter case
 * an unmanaged page table page will be entered into the pass in pmap.
 */
static
pv_entry_t
pmap_allocpte_seg(pmap_t pmap, vm_pindex_t ptepindex, pv_entry_t *pvpp,
                  vm_map_entry_t entry, vm_offset_t va)
{
        vm_object_t object;
        pmap_t obpmap;
        pmap_t *obpmapp;
        vm_offset_t b;
        pv_entry_t pte_pv;      /* in original or shared pmap */
        pv_entry_t pt_pv;       /* in original or shared pmap */
        pv_entry_t proc_pd_pv;  /* in original pmap */
        pv_entry_t proc_pt_pv;  /* in original pmap */
        pv_entry_t xpv;         /* PT in shared pmap */
        pd_entry_t *pt;         /* PT entry in PD of original pmap */
        pd_entry_t opte;        /* contents of *pt */
        pd_entry_t npte;        /* contents of *pt */
        vm_page_t m;

        /*
         * Basic tests, require a non-NULL vm_map_entry, require proper
         * alignment and type for the vm_map_entry, require that the
         * underlying object already be allocated.
         *
         * We allow almost any type of object to use this optimization.
         * The object itself does NOT have to be sized to a multiple of the
         * segment size, but the memory mapping does.
         *
         * XXX don't handle devices currently, because VM_PAGE_TO_PHYS()
         *     won't work as expected.
         */
        if (entry == NULL ||
            pmap_mmu_optimize == 0 ||                   /* not enabled */
            (pmap->pm_flags & PMAP_HVM) ||              /* special pmap */
            ptepindex >= pmap_pd_pindex(0) ||           /* not terminal or pt */
            entry->inheritance != VM_INHERIT_SHARE ||   /* not shared */
            entry->maptype != VM_MAPTYPE_NORMAL ||      /* weird map type */
            entry->object.vm_object == NULL ||          /* needs VM object */
            entry->object.vm_object->type == OBJT_DEVICE ||     /* ick */
            entry->object.vm_object->type == OBJT_MGTDEVICE ||  /* ick */
            (entry->offset & SEG_MASK) ||               /* must be aligned */
            (entry->start & SEG_MASK)) {
                return(pmap_allocpte(pmap, ptepindex, pvpp));
        }

        /*
         * Make sure the full segment can be represented.
         */
        b = va & ~(vm_offset_t)SEG_MASK;
        if (b < entry->start || b + SEG_SIZE > entry->end)
                return(pmap_allocpte(pmap, ptepindex, pvpp));

        /*
         * If the full segment can be represented dive the VM object's
         * shared pmap, allocating as required.
         */
        object = entry->object.vm_object;

        if (entry->protection & VM_PROT_WRITE)
                obpmapp = &object->md.pmap_rw;
        else
                obpmapp = &object->md.pmap_ro;

#ifdef PMAP_DEBUG2
        if (pmap_enter_debug > 0) {
                --pmap_enter_debug;
                kprintf("pmap_allocpte_seg: va=%jx prot %08x o=%p "
                        "obpmapp %p %p\n",
                        va, entry->protection, object,
                        obpmapp, *obpmapp);
                kprintf("pmap_allocpte_seg: entry %p %jx-%jx\n",
                        entry, entry->start, entry->end);
        }
#endif

        /*
         * We allocate what appears to be a normal pmap but because portions
         * of this pmap are shared with other unrelated pmaps we have to
         * set pm_active to point to all cpus.
         *
         * XXX Currently using pmap_spin to interlock the update, can't use
         *     vm_object_hold/drop because the token might already be held
         *     shared OR exclusive and we don't know.
         */
        while ((obpmap = *obpmapp) == NULL) {
                obpmap = kmalloc(sizeof(*obpmap), M_OBJPMAP, M_WAITOK|M_ZERO);
                pmap_pinit_simple(obpmap);
                pmap_pinit2(obpmap);
                spin_lock(&pmap_spin);
                if (*obpmapp != NULL) {
                        /*
                         * Handle race
                         */
                        spin_unlock(&pmap_spin);
                        pmap_release(obpmap);
                        pmap_puninit(obpmap);
                        kfree(obpmap, M_OBJPMAP);
                        obpmap = *obpmapp; /* safety */
                } else {
                        obpmap->pm_active = smp_active_mask;
                        obpmap->pm_flags |= PMAP_SEGSHARED;
                        *obpmapp = obpmap;
                        spin_unlock(&pmap_spin);
                }
        }

        /*
         * Layering is: PTE, PT, PD, PDP, PML4.  We have to return the
         * pte/pt using the shared pmap from the object but also adjust
         * the process pmap's page table page as a side effect.
         */

        /*
         * Resolve the terminal PTE and PT in the shared pmap.  This is what
         * we will return.  This is true if ptepindex represents a terminal
         * page, otherwise pte_pv is actually the PT and pt_pv is actually
         * the PD.
         */
        pt_pv = NULL;
        pte_pv = pmap_allocpte(obpmap, ptepindex, &pt_pv);
retry:
        if (ptepindex >= pmap_pt_pindex(0))
                xpv = pte_pv;
        else
                xpv = pt_pv;

        /*
         * Resolve the PD in the process pmap so we can properly share the
         * page table page.  Lock order is bottom-up (leaf first)!
         *
         * NOTE: proc_pt_pv can be NULL.
         */
        proc_pt_pv = pv_get(pmap, pmap_pt_pindex(b), NULL);
        proc_pd_pv = pmap_allocpte(pmap, pmap_pd_pindex(b), NULL);
#ifdef PMAP_DEBUG2
        if (pmap_enter_debug > 0) {
                --pmap_enter_debug;
                kprintf("proc_pt_pv %p (wc %d) pd_pv %p va=%jx\n",
                        proc_pt_pv,
                        (proc_pt_pv ? proc_pt_pv->pv_m->wire_count : -1),
                        proc_pd_pv,
                        va);
        }
#endif

        /*
         * xpv is the page table page pv from the shared object
         * (for convenience), from above.
         *
         * Calculate the pte value for the PT to load into the process PD.
         * If we have to change it we must properly dispose of the previous
         * entry.
         */
        pt = pv_pte_lookup(proc_pd_pv, pmap_pt_index(b));
        npte = VM_PAGE_TO_PHYS(xpv->pv_m) |
               (pmap->pmap_bits[PG_U_IDX] |
                pmap->pmap_bits[PG_RW_IDX] |
                pmap->pmap_bits[PG_V_IDX] |
                pmap->pmap_bits[PG_A_IDX] |
                pmap->pmap_bits[PG_M_IDX]);

        /*
         * Dispose of previous page table page if it was local to the
         * process pmap.  If the old pt is not empty we cannot dispose of it
         * until we clean it out.  This case should not arise very often so
         * it is not optimized.
         *
         * Leave pt_pv and pte_pv (in our object pmap) locked and intact
         * for the retry.
         */
        if (proc_pt_pv) {
                pmap_inval_bulk_t bulk;

                if (proc_pt_pv->pv_m->wire_count != 1) {
                        pv_put(proc_pd_pv);
                        pv_put(proc_pt_pv);
                        pmap_remove(pmap,
                                    va & ~(vm_offset_t)SEG_MASK,
                                    (va + SEG_SIZE) & ~(vm_offset_t)SEG_MASK);
                        goto retry;
                }

                /*
                 * The release call will indirectly clean out *pt
                 */
                pmap_inval_bulk_init(&bulk, proc_pt_pv->pv_pmap);
                pmap_release_pv(proc_pt_pv, proc_pd_pv, &bulk);
                pmap_inval_bulk_flush(&bulk);
                proc_pt_pv = NULL;
                /* relookup */
                pt = pv_pte_lookup(proc_pd_pv, pmap_pt_index(b));
        }

        /*
         * Handle remaining cases.
         */
        if (*pt == 0) {
                atomic_swap_long(pt, npte);
                vm_page_wire_quick(xpv->pv_m);          /* shared pt -> proc */
                vm_page_wire_quick(proc_pd_pv->pv_m);   /* proc pd for sh pt */
                atomic_add_long(&pmap->pm_stats.resident_count, 1);
        } else if (*pt != npte) {
                opte = pmap_inval_smp(pmap, (vm_offset_t)-1, 1, pt, npte);

#if 0
                opte = pte_load_clear(pt);
                KKASSERT(opte && opte != npte);

                *pt = npte;
#endif
                vm_page_wire_quick(xpv->pv_m);          /* shared pt -> proc */

                /*
                 * Clean up opte, bump the wire_count for the process
                 * PD page representing the new entry if it was
                 * previously empty.
                 *
                 * If the entry was not previously empty and we have
                 * a PT in the proc pmap then opte must match that
                 * pt.  The proc pt must be retired (this is done
                 * later on in this procedure).
                 *
                 * NOTE: replacing valid pte, wire_count on proc_pd_pv
                 * stays the same.
                 */
                KKASSERT(opte & pmap->pmap_bits[PG_V_IDX]);
                m = PHYS_TO_VM_PAGE(opte & PG_FRAME);
                if (vm_page_unwire_quick(m)) {
                        panic("pmap_allocpte_seg: "
                              "bad wire count %p",
                              m);
                }
        }

        /*
         * The existing process page table was replaced and must be destroyed
         * here.
         */
        if (proc_pd_pv)
                pv_put(proc_pd_pv);
        if (pvpp)
                *pvpp = pt_pv;
        else
                pv_put(pt_pv);

        return (pte_pv);
}

/*
 * 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.
 */
struct pmap_release_info {
        pmap_t  pmap;
        int     retry;
        pv_entry_t pvp;
};

static int pmap_release_callback(pv_entry_t pv, void *data);

void
pmap_release(struct pmap *pmap)
{
        struct pmap_release_info info;

        KASSERT(CPUMASK_TESTZERO(pmap->pm_active),
                ("pmap still active! %016jx",
                (uintmax_t)CPUMASK_LOWMASK(pmap->pm_active)));

        /*
         * There is no longer a pmap_list, if there were we would remove the
         * pmap from it here.
         */

        /*
         * Pull pv's off the RB tree in order from low to high and release
         * each page.
         */
        info.pmap = pmap;
        do {
                info.retry = 0;
                info.pvp = NULL;

                spin_lock(&pmap->pm_spin);
                RB_SCAN(pv_entry_rb_tree, &pmap->pm_pvroot, NULL,
                        pmap_release_callback, &info);
                spin_unlock(&pmap->pm_spin);

                if (info.pvp)
                        pv_put(info.pvp);
        } while (info.retry);


        /*
         * One resident page (the pml4 page) should remain.
         * No wired pages should remain.
         */
#if 1
        if (pmap->pm_stats.resident_count !=
            ((pmap->pm_flags & PMAP_FLAG_SIMPLE) ? 0 : 1) ||
            pmap->pm_stats.wired_count != 0) {
                kprintf("fatal pmap problem - pmap %p flags %08x "
                        "rescnt=%jd wirecnt=%jd\n",
                        pmap,
                        pmap->pm_flags,
                        pmap->pm_stats.resident_count,
                        pmap->pm_stats.wired_count);
                tsleep(pmap, 0, "DEAD", 0);
        }
#else
        KKASSERT(pmap->pm_stats.resident_count ==
                 ((pmap->pm_flags & PMAP_FLAG_SIMPLE) ? 0 : 1));
        KKASSERT(pmap->pm_stats.wired_count == 0);
#endif
}

/*
 * Called from low to high.  We must cache the proper parent pv so we
 * can adjust its wired count.
 */
static int
pmap_release_callback(pv_entry_t pv, void *data)
{
        struct pmap_release_info *info = data;
        pmap_t pmap = info->pmap;
        vm_pindex_t pindex;
        int r;

        /*
         * Acquire a held and locked pv, check for release race
         */
        pindex = pv->pv_pindex;
        if (info->pvp == pv) {
                spin_unlock(&pmap->pm_spin);
                info->pvp = NULL;
        } else if (pv_hold_try(pv)) {
                spin_unlock(&pmap->pm_spin);
        } else {
                spin_unlock(&pmap->pm_spin);
                pv_lock(pv);
                pv_put(pv);
                info->retry = 1;
                spin_lock(&pmap->pm_spin);

                return -1;
        }
        KKASSERT(pv->pv_pmap == pmap && pindex == pv->pv_pindex);

        if (pv->pv_pindex < pmap_pt_pindex(0)) {
                /*
                 * I am PTE, parent is PT
                 */
                pindex = pv->pv_pindex >> NPTEPGSHIFT;
                pindex += NUPTE_TOTAL;
        } else if (pv->pv_pindex < pmap_pd_pindex(0)) {
                /*
                 * I am PT, parent is PD
                 */
                pindex = (pv->pv_pindex - NUPTE_TOTAL) >> NPDEPGSHIFT;
                pindex += NUPTE_TOTAL + NUPT_TOTAL;
        } else if (pv->pv_pindex < pmap_pdp_pindex(0)) {
                /*
                 * I am PD, parent is PDP
                 */
                pindex = (pv->pv_pindex - NUPTE_TOTAL - NUPT_TOTAL) >>
                         NPDPEPGSHIFT;
                pindex += NUPTE_TOTAL + NUPT_TOTAL + NUPD_TOTAL;
        } else if (pv->pv_pindex < pmap_pml4_pindex()) {
                /*
                 * I am PDP, parent is PML4 (there's only one)
                 */
#if 0
                pindex = (pv->pv_pindex - NUPTE_TOTAL - NUPT_TOTAL -
                           NUPD_TOTAL) >> NPML4EPGSHIFT;
                pindex += NUPTE_TOTAL + NUPT_TOTAL + NUPD_TOTAL + NUPDP_TOTAL;
#endif
                pindex = pmap_pml4_pindex();
        } else {
                /*
                 * parent is NULL
                 */
                if (info->pvp) {
                        pv_put(info->pvp);
                        info->pvp = NULL;
                }
                pindex = 0;
        }
        if (pindex) {
                if (info->pvp && info->pvp->pv_pindex != pindex) {
                        pv_put(info->pvp);
                        info->pvp = NULL;
                }
                if (info->pvp == NULL)
                        info->pvp = pv_get(pmap, pindex, NULL);
        } else {
                if (info->pvp) {
                        pv_put(info->pvp);
                        info->pvp = NULL;
                }
        }
        r = pmap_release_pv(pv, info->pvp, NULL);
        spin_lock(&pmap->pm_spin);

        return(r);
}

/*
 * Called with held (i.e. also locked) pv.  This function will dispose of
 * the lock along with the pv.
 *
 * If the caller already holds the locked parent page table for pv it
 * must pass it as pvp, allowing us to avoid a deadlock, else it can
 * pass NULL for pvp.
 */
static int
pmap_release_pv(pv_entry_t pv, pv_entry_t pvp, pmap_inval_bulk_t *bulk)
{
        vm_page_t p;

        /*
         * The pmap is currently not spinlocked, pv is held+locked.
         * Remove the pv's page from its parent's page table.  The
         * parent's page table page's wire_count will be decremented.
         *
         * This will clean out the pte at any level of the page table.
         * If smp != 0 all cpus are affected.
         *
         * Do not tear-down recursively, its faster to just let the
         * release run its course.
         */
        pmap_remove_pv_pte(pv, pvp, bulk, 0);

        /*
         * Terminal pvs are unhooked from their vm_pages.  Because
         * terminal pages aren't page table pages they aren't wired
         * by us, so we have to be sure not to unwire them either.
         */
        if (pv->pv_pindex < pmap_pt_pindex(0)) {
                pmap_remove_pv_page(pv);
                goto skip;
        }

        /*
         * We leave the top-level page table page cached, wired, and
         * mapped in the pmap until the dtor function (pmap_puninit())
         * gets called.
         *
         * Since we are leaving the top-level pv intact we need
         * to break out of what would otherwise be an infinite loop.
         */
        if (pv->pv_pindex == pmap_pml4_pindex()) {
                pv_put(pv);
                return(-1);
        }

        /*
         * For page table pages (other than the top-level page),
         * remove and free the vm_page.  The representitive mapping
         * removed above by pmap_remove_pv_pte() did not undo the
         * last wire_count so we have to do that as well.
         */
        p = pmap_remove_pv_page(pv);
        vm_page_busy_wait(p, FALSE, "pmaprl");
        if (p->wire_count != 1) {
                kprintf("p->wire_count was %016lx %d\n",
                        pv->pv_pindex, p->wire_count);
        }
        KKASSERT(p->wire_count == 1);
        KKASSERT(p->flags & PG_UNMANAGED);

        vm_page_unwire(p, 0);
        KKASSERT(p->wire_count == 0);

        vm_page_free(p);
skip:
        pv_free(pv, pvp);

        return 0;
}

/*
 * This function will remove the pte associated with a pv from its parent.
 * Terminal pv's are supported.  All cpus specified by (bulk) are properly
 * invalidated.
 *
 * The wire count will be dropped on the parent page table.  The wire
 * count on the page being removed (pv->pv_m) from the parent page table
 * is NOT touched.  Note that terminal pages will not have any additional
 * wire counts while page table pages will have at least one representing
 * the mapping, plus others representing sub-mappings.
 *
 * NOTE: Cannot be called on kernel page table pages, only KVM terminal
 *       pages and user page table and terminal pages.
 *
 * NOTE: The pte being removed might be unmanaged, and the pv supplied might
 *       be freshly allocated and not imply that the pte is managed.  In this
 *       case pv->pv_m should be NULL.
 *
 * The pv must be locked.  The pvp, if supplied, must be locked.  All
 * supplied pv's will remain locked on return.
 *
 * XXX must lock parent pv's if they exist to remove pte XXX
 */
static
void
pmap_remove_pv_pte(pv_entry_t pv, pv_entry_t pvp, pmap_inval_bulk_t *bulk,
                   int destroy)
{
        vm_pindex_t ptepindex = pv->pv_pindex;
        pmap_t pmap = pv->pv_pmap;
        vm_page_t p;
        int gotpvp = 0;

        KKASSERT(pmap);

        if (ptepindex == pmap_pml4_pindex()) {
                /*
                 * We are the top level PML4E table, there is no parent.
                 */
                p = pmap->pm_pmlpv->pv_m;
                KKASSERT(pv->pv_m == p);        /* debugging */
        } else if (ptepindex >= pmap_pdp_pindex(0)) {
                /*
                 * Remove a PDP page from the PML4E.  This can only occur
                 * with user page tables.  We do not have to lock the
                 * pml4 PV so just ignore pvp.
                 */
                vm_pindex_t pml4_pindex;
                vm_pindex_t pdp_index;
                pml4_entry_t *pdp;

                pdp_index = ptepindex - pmap_pdp_pindex(0);
                if (pvp == NULL) {
                        pml4_pindex = pmap_pml4_pindex();
                        pvp = pv_get(pv->pv_pmap, pml4_pindex, NULL);
                        KKASSERT(pvp);
                        gotpvp = 1;
                }

                pdp = &pmap->pm_pml4[pdp_index & ((1ul << NPML4EPGSHIFT) - 1)];
                KKASSERT((*pdp & pmap->pmap_bits[PG_V_IDX]) != 0);
                p = PHYS_TO_VM_PAGE(*pdp & PG_FRAME);
                pmap_inval_bulk(bulk, (vm_offset_t)-1, pdp, 0);
                KKASSERT(pv->pv_m == p);        /* debugging */
        } else if (ptepindex >= pmap_pd_pindex(0)) {
                /*
                 * Remove a PD page from the PDP
                 *
                 * SIMPLE PMAP NOTE: Non-existant pvp's are ok in the case
                 *                   of a simple pmap because it stops at
                 *                   the PD page.
                 */
                vm_pindex_t pdp_pindex;
                vm_pindex_t pd_index;
                pdp_entry_t *pd;

                pd_index = ptepindex - pmap_pd_pindex(0);

                if (pvp == NULL) {
                        pdp_pindex = NUPTE_TOTAL + NUPT_TOTAL + NUPD_TOTAL +
                                     (pd_index >> NPML4EPGSHIFT);
                        pvp = pv_get(pv->pv_pmap, pdp_pindex, NULL);
                        gotpvp = 1;
                }

                if (pvp) {
                        pd = pv_pte_lookup(pvp, pd_index &
                                                ((1ul << NPDPEPGSHIFT) - 1));
                        KKASSERT((*pd & pmap->pmap_bits[PG_V_IDX]) != 0);
                        p = PHYS_TO_VM_PAGE(*pd & PG_FRAME);
                        pmap_inval_bulk(bulk, (vm_offset_t)-1, pd, 0);
                } else {
                        KKASSERT(pmap->pm_flags & PMAP_FLAG_SIMPLE);
                        p = pv->pv_m;           /* degenerate test later */
                }
                KKASSERT(pv->pv_m == p);        /* debugging */
        } else if (ptepindex >= pmap_pt_pindex(0)) {
                /*
                 *  Remove a PT page from the PD
                 */
                vm_pindex_t pd_pindex;
                vm_pindex_t pt_index;
                pd_entry_t *pt;

                pt_index = ptepindex - pmap_pt_pindex(0);

                if (pvp == NULL) {
                        pd_pindex = NUPTE_TOTAL + NUPT_TOTAL +
                                    (pt_index >> NPDPEPGSHIFT);
                        pvp = pv_get(pv->pv_pmap, pd_pindex, NULL);
                        KKASSERT(pvp);
                        gotpvp = 1;
                }

                pt = pv_pte_lookup(pvp, pt_index & ((1ul << NPDPEPGSHIFT) - 1));
#if 0
                KASSERT((*pt & pmap->pmap_bits[PG_V_IDX]) != 0,
                        ("*pt unexpectedly invalid %016jx "
                         "gotpvp=%d ptepindex=%ld ptindex=%ld pv=%p pvp=%p",
                        *pt, gotpvp, ptepindex, pt_index, pv, pvp));
                p = PHYS_TO_VM_PAGE(*pt & PG_FRAME);
#else
                if ((*pt & pmap->pmap_bits[PG_V_IDX]) == 0) {
                        kprintf("*pt unexpectedly invalid %016jx "
                                "gotpvp=%d ptepindex=%ld ptindex=%ld "
                                "pv=%p pvp=%p\n",
                                *pt, gotpvp, ptepindex, pt_index, pv, pvp);
                        tsleep(pt, 0, "DEAD", 0);
                        p = pv->pv_m;
                } else {
                        p = PHYS_TO_VM_PAGE(*pt & PG_FRAME);
                }
#endif
                pmap_inval_bulk(bulk, (vm_offset_t)-1, pt, 0);
                KKASSERT(pv->pv_m == p);        /* debugging */
        } else {
                /*
                 * Remove a PTE from the PT page.  The PV might exist even if
                 * the PTE is not managed, in whichcase pv->pv_m should be
                 * NULL.
                 *
                 * NOTE: Userland pmaps manage the parent PT/PD/PDP page
                 *       table pages but the kernel_pmap does not.
                 *
                 * NOTE: pv's must be locked bottom-up to avoid deadlocking.
                 *       pv is a pte_pv so we can safely lock pt_pv.
                 *
                 * NOTE: FICTITIOUS pages may have multiple physical mappings
                 *       so PHYS_TO_VM_PAGE() will not necessarily work for
                 *       terminal ptes.
                 */
                vm_pindex_t pt_pindex;
                pt_entry_t *ptep;
                pt_entry_t pte;
                vm_offset_t va;

                pt_pindex = ptepindex >> NPTEPGSHIFT;
                va = (vm_offset_t)ptepindex << PAGE_SHIFT;

                if (ptepindex >= NUPTE_USER) {
                        ptep = vtopte(ptepindex << PAGE_SHIFT);
                        KKASSERT(pvp == NULL);
                        /* pvp remains NULL */
                } else {
                        if (pvp == NULL) {
                                pt_pindex = NUPTE_TOTAL +
                                            (ptepindex >> NPDPEPGSHIFT);
                                pvp = pv_get(pv->pv_pmap, pt_pindex, NULL);
                                KKASSERT(pvp);
                                gotpvp = 1;
                        }
                        ptep = pv_pte_lookup(pvp, ptepindex &
                                                  ((1ul << NPDPEPGSHIFT) - 1));
                }
                pte = pmap_inval_bulk(bulk, va, ptep, 0);
                if (bulk == NULL)               /* XXX */
                        cpu_invlpg((void *)va); /* XXX */

                /*
                 * Now update the vm_page_t
                 */
                if ((pte & pmap->pmap_bits[PG_MANAGED_IDX]) &&
                    (pte & pmap->pmap_bits[PG_V_IDX])) {
                        /*
                         * Valid managed page, adjust (p).
                         */
                        if (pte & pmap->pmap_bits[PG_DEVICE_IDX]) {
                                p = pv->pv_m;
                        } else {
                                p = PHYS_TO_VM_PAGE(pte & PG_FRAME);
                                KKASSERT(pv->pv_m == p);
                        }
                        if (pte & pmap->pmap_bits[PG_M_IDX]) {
                                if (pmap_track_modified(ptepindex))
                                        vm_page_dirty(p);
                        }
                        if (pte & pmap->pmap_bits[PG_A_IDX]) {
                                vm_page_flag_set(p, PG_REFERENCED);
                        }
                } else {
                        /*
                         * Unmanaged page, do not try to adjust the vm_page_t.
                         * pv could be freshly allocated for a pmap_enter(),
                         * replacing an unmanaged page with a managed one.
                         *
                         * pv->pv_m might reflect the new page and not the
                         * existing page.
                         *
                         * We could extract p from the physical address and
                         * adjust it but we explicitly do not for unmanaged
                         * pages.
                         */
                        p = NULL;
                }
                if (pte & pmap->pmap_bits[PG_W_IDX])
                        atomic_add_long(&pmap->pm_stats.wired_count, -1);
                if (pte & pmap->pmap_bits[PG_G_IDX])
                        cpu_invlpg((void *)va);
        }

        /*
         * If requested, scrap the underlying pv->pv_m and the underlying
         * pv.  If this is a page-table-page we must also free the page.
         *
         * pvp must be returned locked.
         */
        if (destroy == 1) {
                /*
                 * page table page (PT, PD, PDP, PML4), caller was responsible
                 * for testing wired_count.
                 */
                KKASSERT(pv->pv_m->wire_count == 1);
                p = pmap_remove_pv_page(pv);
                pv_free(pv, pvp);
                pv = NULL;

                vm_page_busy_wait(p, FALSE, "pgpun");
                vm_page_unwire(p, 0);
                vm_page_flag_clear(p, PG_MAPPED | PG_WRITEABLE);
                vm_page_free(p);
        } else if (destroy == 2) {
                /*
                 * Normal page, remove from pmap and leave the underlying
                 * page untouched.
                 */
                pmap_remove_pv_page(pv);
                pv_free(pv, pvp);
                pv = NULL;              /* safety */
        }

        /*
         * If we acquired pvp ourselves then we are responsible for
         * recursively deleting it.
         */
        if (pvp && gotpvp) {
                /*
                 * Recursively destroy higher-level page tables.
                 *
                 * This is optional.  If we do not, they will still
                 * be destroyed when the process exits.
                 *
                 * NOTE: Do not destroy pv_entry's with extra hold refs,
                 *       a caller may have unlocked it and intends to
                 *       continue to use it.
                 */
                if (pmap_dynamic_delete &&
                    pvp->pv_m &&
                    pvp->pv_m->wire_count == 1 &&
                    (pvp->pv_hold & PV_HOLD_MASK) == 2 &&
                    pvp->pv_pindex != pmap_pml4_pindex()) {
                        if (pmap_dynamic_delete == 2)
                                kprintf("A %jd %08x\n", pvp->pv_pindex, pvp->pv_hold);
                        if (pmap != &kernel_pmap) {
                                pmap_remove_pv_pte(pvp, NULL, bulk, 1);
                                pvp = NULL;     /* safety */
                        } else {
                                kprintf("Attempt to remove kernel_pmap pindex "
                                        "%jd\n", pvp->pv_pindex);
                                pv_put(pvp);
                        }
                } else {
                        pv_put(pvp);
                }
        }
}

/*
 * Remove the vm_page association to a pv.  The pv must be locked.
 */
static
vm_page_t
pmap_remove_pv_page(pv_entry_t pv)
{
        vm_page_t m;

        m = pv->pv_m;
        vm_page_spin_lock(m);
        KKASSERT(m && m == pv->pv_m);
        pv->pv_m = NULL;
        TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
        pmap_page_stats_deleting(m);
        if (TAILQ_EMPTY(&m->md.pv_list))
                vm_page_flag_clear(m, PG_MAPPED | PG_WRITEABLE);
        vm_page_spin_unlock(m);

        return(m);
}

/*
 * Grow the number of kernel page table entries, if needed.
 *
 * This routine is always called to validate any address space
 * beyond KERNBASE (for kldloads).  kernel_vm_end only governs the address
 * space below KERNBASE.
 *
 * kernel_map must be locked exclusively by the caller.
 */
void
pmap_growkernel(vm_offset_t kstart, vm_offset_t kend)
{
        vm_paddr_t paddr;
        vm_offset_t ptppaddr;
        vm_page_t nkpg;
        pd_entry_t *pt, newpt;
        pdp_entry_t newpd;
        int update_kernel_vm_end;

        /*
         * bootstrap kernel_vm_end on first real VM use
         */
        if (kernel_vm_end == 0) {
                kernel_vm_end = VM_MIN_KERNEL_ADDRESS;
                nkpt = 0;
                while ((*pmap_pt(&kernel_pmap, kernel_vm_end) & kernel_pmap.pmap_bits[PG_V_IDX]) != 0) {
                        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;                       
                        }
                }
        }

        /*
         * Fill in the gaps.  kernel_vm_end is only adjusted for ranges
         * below KERNBASE.  Ranges above KERNBASE are kldloaded and we
         * do not want to force-fill 128G worth of page tables.
         */
        if (kstart < KERNBASE) {
                if (kstart > kernel_vm_end)
                        kstart = kernel_vm_end;
                KKASSERT(kend <= KERNBASE);
                update_kernel_vm_end = 1;
        } else {
                update_kernel_vm_end = 0;
        }

        kstart = rounddown2(kstart, PAGE_SIZE * NPTEPG);
        kend = roundup2(kend, PAGE_SIZE * NPTEPG);

        if (kend - 1 >= kernel_map.max_offset)
                kend = kernel_map.max_offset;

        while (kstart < kend) {
                pt = pmap_pt(&kernel_pmap, kstart);
                if (pt == NULL) {
                        /* We need a new PD entry */
                        nkpg = vm_page_alloc(NULL, mycpu->gd_rand_incr++,
                                             VM_ALLOC_NORMAL |
                                             VM_ALLOC_SYSTEM |
                                             VM_ALLOC_INTERRUPT);
                        if (nkpg == NULL) {
                                panic("pmap_growkernel: no memory to grow "
                                      "kernel");
                        }
                        paddr = VM_PAGE_TO_PHYS(nkpg);
                        pmap_zero_page(paddr);
                        newpd = (pdp_entry_t)
                            (paddr |
                            kernel_pmap.pmap_bits[PG_V_IDX] |
                            kernel_pmap.pmap_bits[PG_RW_IDX] |
                            kernel_pmap.pmap_bits[PG_A_IDX] |
                            kernel_pmap.pmap_bits[PG_M_IDX]);
                        *pmap_pd(&kernel_pmap, kstart) = newpd;
                        continue; /* try again */
                }
                if ((*pt & kernel_pmap.pmap_bits[PG_V_IDX]) != 0) {
                        kstart = (kstart + PAGE_SIZE * NPTEPG) &
                                 ~(PAGE_SIZE * NPTEPG - 1);
                        if (kstart - 1 >= kernel_map.max_offset) {
                                kstart = kernel_map.max_offset;
                                break;                       
                        }
                        continue;
                }

                /*
                 * We need a new PT
                 *
                 * This index is bogus, but out of the way
                 */
                nkpg = vm_page_alloc(NULL, mycpu->gd_rand_incr++,
                                     VM_ALLOC_NORMAL |
                                     VM_ALLOC_SYSTEM |
                                     VM_ALLOC_INTERRUPT);
                if (nkpg == NULL)
                        panic("pmap_growkernel: no memory to grow kernel");

                vm_page_wire(nkpg);
                ptppaddr = VM_PAGE_TO_PHYS(nkpg);
                pmap_zero_page(ptppaddr);
                newpt = (pd_entry_t)(ptppaddr |
                                     kernel_pmap.pmap_bits[PG_V_IDX] |
                                     kernel_pmap.pmap_bits[PG_RW_IDX] |
                                     kernel_pmap.pmap_bits[PG_A_IDX] |
                                     kernel_pmap.pmap_bits[PG_M_IDX]);
                atomic_swap_long(pmap_pt(&kernel_pmap, kstart), newpt);

                kstart = (kstart + PAGE_SIZE * NPTEPG) &
                          ~(PAGE_SIZE * NPTEPG - 1);

                if (kstart - 1 >= kernel_map.max_offset) {
                        kstart = kernel_map.max_offset;
                        break;                       
                }
        }

        /*
         * Only update kernel_vm_end for areas below KERNBASE.
         */
        if (update_kernel_vm_end && kernel_vm_end < kstart)
                kernel_vm_end = kstart;
}

/*
 *      Add a reference to the specified pmap.
 */
void
pmap_reference(pmap_t pmap)
{
        if (pmap != NULL)
                atomic_add_int(&pmap->pm_count, 1);
}

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

/*
 * Hold a pv without locking it
 */
static void
pv_hold(pv_entry_t pv)
{
        atomic_add_int(&pv->pv_hold, 1);
}

/*
 * Hold a pv_entry, preventing its destruction.  TRUE is returned if the pv
 * was successfully locked, FALSE if it wasn't.  The caller must dispose of
 * the pv properly.
 *
 * Either the pmap->pm_spin or the related vm_page_spin (if traversing a
 * pv list via its page) must be held by the caller in order to stabilize
 * the pv.
 */
static int
_pv_hold_try(pv_entry_t pv PMAP_DEBUG_DECL)
{
        u_int count;

        /*
         * Critical path shortcut expects pv to already have one ref
         * (for the pv->pv_pmap).
         */
        if (atomic_cmpset_int(&pv->pv_hold, 1, PV_HOLD_LOCKED | 2)) {
#ifdef PMAP_DEBUG
                pv->pv_func = func;
                pv->pv_line = lineno;
#endif
                return TRUE;
        }

        for (;;) {
                count = pv->pv_hold;
                cpu_ccfence();
                if ((count & PV_HOLD_LOCKED) == 0) {
                        if (atomic_cmpset_int(&pv->pv_hold, count,
                                              (count + 1) | PV_HOLD_LOCKED)) {
#ifdef PMAP_DEBUG
                                pv->pv_func = func;
                                pv->pv_line = lineno;
#endif
                                return TRUE;
                        }
                } else {
                        if (atomic_cmpset_int(&pv->pv_hold, count, count + 1))
                                return FALSE;
                }
                /* retry */
        }
}

/*
 * Drop a previously held pv_entry which could not be locked, allowing its
 * destruction.
 *
 * Must not be called with a spinlock held as we might zfree() the pv if it
 * is no longer associated with a pmap and this was the last hold count.
 */
static void
pv_drop(pv_entry_t pv)
{
        u_int count;

        for (;;) {
                count = pv->pv_hold;
                cpu_ccfence();
                KKASSERT((count & PV_HOLD_MASK) > 0);
                KKASSERT((count & (PV_HOLD_LOCKED | PV_HOLD_MASK)) !=
                         (PV_HOLD_LOCKED | 1));
                if (atomic_cmpset_int(&pv->pv_hold, count, count - 1)) {
                        if ((count & PV_HOLD_MASK) == 1) {
#ifdef PMAP_DEBUG2
                                if (pmap_enter_debug > 0) {
                                        --pmap_enter_debug;
                                        kprintf("pv_drop: free pv %p\n", pv);
                                }
#endif
                                KKASSERT(count == 1);
                                KKASSERT(pv->pv_pmap == NULL);
                                zfree(pvzone, pv);
                        }
                        return;
                }
                /* retry */
        }
}

/*
 * Find or allocate the requested PV entry, returning a locked, held pv.
 *
 * If (*isnew) is non-zero, the returned pv will have two hold counts, one
 * for the caller and one representing the pmap and vm_page association.
 *
 * If (*isnew) is zero, the returned pv will have only one hold count.
 *
 * Since both associations can only be adjusted while the pv is locked,
 * together they represent just one additional hold.
 */
static
pv_entry_t
_pv_alloc(pmap_t pmap, vm_pindex_t pindex, int *isnew PMAP_DEBUG_DECL)
{
        struct mdglobaldata *md = mdcpu;
        pv_entry_t pv;
        pv_entry_t pnew;
        int pmap_excl = 0;

        pnew = NULL;
        if (md->gd_newpv) {
#if 0
                pnew = atomic_swap_ptr((void *)&md->gd_newpv, NULL);
#else
                crit_enter();
                pnew = md->gd_newpv;    /* might race NULL */
                md->gd_newpv = NULL;
                crit_exit();
#endif
        }
        if (pnew == NULL)
                pnew = zalloc(pvzone);

        spin_lock_shared(&pmap->pm_spin);
        for (;;) {
                /*
                 * Shortcut cache
                 */
                pv = pmap->pm_pvhint;
                cpu_ccfence();
                if (pv == NULL ||
                    pv->pv_pmap != pmap ||
                    pv->pv_pindex != pindex) {
                        pv = pv_entry_rb_tree_RB_LOOKUP(&pmap->pm_pvroot,
                                                        pindex);
                }
                if (pv == NULL) {
                        vm_pindex_t *pmark;

                        /*
                         * Requires exclusive pmap spinlock
                         */
                        if (pmap_excl == 0) {
                                pmap_excl = 1;
                                if (!spin_lock_upgrade_try(&pmap->pm_spin)) {
                                        spin_unlock_shared(&pmap->pm_spin);
                                        spin_lock(&pmap->pm_spin);
                                        continue;
                                }
                        }

                        /*
                         * We need to block if someone is holding our
                         * placemarker.  As long as we determine the
                         * placemarker has not been aquired we do not
                         * need to get it as acquision also requires
                         * the pmap spin lock.
                         *
                         * However, we can race the wakeup.
                         */
                        pmark = pmap_placemarker_hash(pmap, pindex);

                        if (((*pmark ^ pindex) & ~PM_PLACEMARK_WAKEUP) == 0) {
                                atomic_set_long(pmark, PM_PLACEMARK_WAKEUP);
                                tsleep_interlock(pmark, 0);
                                if (((*pmark ^ pindex) &
                                     ~PM_PLACEMARK_WAKEUP) == 0) {
                                        spin_unlock(&pmap->pm_spin);
                                        tsleep(pmark, PINTERLOCKED, "pvplc", 0);
                                        spin_lock(&pmap->pm_spin);
                                }
                                continue;
                        }

                        /*
                         * Setup the new entry
                         */
                        pnew->pv_pmap = pmap;
                        pnew->pv_pindex = pindex;
                        pnew->pv_hold = PV_HOLD_LOCKED | 2;
#ifdef PMAP_DEBUG
                        pnew->pv_func = func;
                        pnew->pv_line = lineno;
                        if (pnew->pv_line_lastfree > 0) {
                                pnew->pv_line_lastfree =
                                                -pnew->pv_line_lastfree;
                        }
#endif
                        pv = pv_entry_rb_tree_RB_INSERT(&pmap->pm_pvroot, pnew);
                        atomic_add_long(&pmap->pm_stats.resident_count, 1);
                        spin_unlock(&pmap->pm_spin);
                        *isnew = 1;

                        KKASSERT(pv == NULL);
                        return(pnew);
                }

                /*
                 * We already have an entry, cleanup the staged pnew if
                 * we can get the lock, otherwise block and retry.
                 */
                if (__predict_true(_pv_hold_try(pv PMAP_DEBUG_COPY))) {
                        if (pmap_excl)
                                spin_unlock(&pmap->pm_spin);
                        else
                                spin_unlock_shared(&pmap->pm_spin);
#if 0
                        pnew = atomic_swap_ptr((void *)&md->gd_newpv, pnew);
                        if (pnew)
                                zfree(pvzone, pnew);
#else
                        crit_enter();
                        if (md->gd_newpv == NULL)
                                md->gd_newpv = pnew;
                        else
                                zfree(pvzone, pnew);
                        crit_exit();
#endif
                        KKASSERT(pv->pv_pmap == pmap &&
                                 pv->pv_pindex == pindex);
                        *isnew = 0;
                        return(pv);
                }
                if (pmap_excl) {
                        spin_unlock(&pmap->pm_spin);
                        _pv_lock(pv PMAP_DEBUG_COPY);
                        pv_put(pv);
                        spin_lock(&pmap->pm_spin);
                } else {
                        spin_unlock_shared(&pmap->pm_spin);
                        _pv_lock(pv PMAP_DEBUG_COPY);
                        pv_put(pv);
                        spin_lock_shared(&pmap->pm_spin);
                }
        }
        /* NOT REACHED */
}

/*
 * Find the requested PV entry, returning a locked+held pv or NULL
 */
static
pv_entry_t
_pv_get(pmap_t pmap, vm_pindex_t pindex, vm_pindex_t **pmarkp PMAP_DEBUG_DECL)
{
        pv_entry_t pv;
        int pmap_excl = 0;

        spin_lock_shared(&pmap->pm_spin);
        for (;;) {
                /*
                 * Shortcut cache
                 */
                pv = pmap->pm_pvhint;
                cpu_ccfence();
                if (pv == NULL ||
                    pv->pv_pmap != pmap ||
                    pv->pv_pindex != pindex) {
                        pv = pv_entry_rb_tree_RB_LOOKUP(&pmap->pm_pvroot,
                                                        pindex);
                }
                if (pv == NULL) {
                        /*
                         * Block if there is ANY placemarker.  If we are to
                         * return it, we must also aquire the spot, so we
                         * have to block even if the placemarker is held on
                         * a different address.
                         *
                         * OPTIMIZATION: If pmarkp is passed as NULL the
                         * caller is just probing (or looking for a real
                         * pv_entry), and in this case we only need to check
                         * to see if the placemarker matches pindex.
                         */
                        vm_pindex_t *pmark;

                        /*
                         * Requires exclusive pmap spinlock
                         */
                        if (pmap_excl == 0) {
                                pmap_excl = 1;
                                if (!spin_lock_upgrade_try(&pmap->pm_spin)) {
                                        spin_unlock_shared(&pmap->pm_spin);
                                        spin_lock(&pmap->pm_spin);
                                        continue;
                                }
                        }

                        pmark = pmap_placemarker_hash(pmap, pindex);

                        if ((pmarkp && *pmark != PM_NOPLACEMARK) ||
                            ((*pmark ^ pindex) & ~PM_PLACEMARK_WAKEUP) == 0) {
                                atomic_set_long(pmark, PM_PLACEMARK_WAKEUP);
                                tsleep_interlock(pmark, 0);
                                if ((pmarkp && *pmark != PM_NOPLACEMARK) ||
                                    ((*pmark ^ pindex) &
                                     ~PM_PLACEMARK_WAKEUP) == 0) {
                                        spin_unlock(&pmap->pm_spin);
                                        tsleep(pmark, PINTERLOCKED, "pvpld", 0);
                                        spin_lock(&pmap->pm_spin);
                                }
                                continue;
                        }
                        if (pmarkp) {
                                if (atomic_swap_long(pmark, pindex) !=
                                    PM_NOPLACEMARK) {
                                        panic("_pv_get: pmark race");
                                }
                                *pmarkp = pmark;
                        }
                        spin_unlock(&pmap->pm_spin);
                        return NULL;
                }
                if (_pv_hold_try(pv PMAP_DEBUG_COPY)) {
                        pv_cache(pv, pindex);
                        if (pmap_excl)
                                spin_unlock(&pmap->pm_spin);
                        else
                                spin_unlock_shared(&pmap->pm_spin);
                        KKASSERT(pv->pv_pmap == pmap &&
                                 pv->pv_pindex == pindex);
                        return(pv);
                }
                if (pmap_excl) {
                        spin_unlock(&pmap->pm_spin);
                        _pv_lock(pv PMAP_DEBUG_COPY);
                        pv_put(pv);
                        spin_lock(&pmap->pm_spin);
                } else {
                        spin_unlock_shared(&pmap->pm_spin);
                        _pv_lock(pv PMAP_DEBUG_COPY);
                        pv_put(pv);
                        spin_lock_shared(&pmap->pm_spin);
                }
        }
}

/*
 * Lookup, hold, and attempt to lock (pmap,pindex).
 *
 * If the entry does not exist NULL is returned and *errorp is set to 0
 *
 * If the entry exists and could be successfully locked it is returned and
 * errorp is set to 0.
 *
 * If the entry exists but could NOT be successfully locked it is returned
 * held and *errorp is set to 1.
 *
 * If the entry is placemarked by someone else NULL is returned and *errorp
 * is set to 1.
 */
static
pv_entry_t
pv_get_try(pmap_t pmap, vm_pindex_t pindex, vm_pindex_t **pmarkp, int *errorp)
{
        pv_entry_t pv;

        spin_lock_shared(&pmap->pm_spin);

        pv = pmap->pm_pvhint;
        cpu_ccfence();
        if (pv == NULL ||
            pv->pv_pmap != pmap ||
            pv->pv_pindex != pindex) {
                pv = pv_entry_rb_tree_RB_LOOKUP(&pmap->pm_pvroot, pindex);
        }

        if (pv == NULL) {
                vm_pindex_t *pmark;

                pmark = pmap_placemarker_hash(pmap, pindex);

                if (((*pmark ^ pindex) & ~PM_PLACEMARK_WAKEUP) == 0) {
                        *errorp = 1;
                } else if (pmarkp &&
                           atomic_cmpset_long(pmark, PM_NOPLACEMARK, pindex)) {
                        *errorp = 0;
                } else {
                        /*
                         * Can't set a placemark with a NULL pmarkp, or if
                         * pmarkp is non-NULL but we failed to set our
                         * placemark.
                         */
                        *errorp = 1;
                }
                if (pmarkp)
                        *pmarkp = pmark;
                spin_unlock_shared(&pmap->pm_spin);

                return NULL;
        }

        /*
         * XXX This has problems if the lock is shared, why?
         */
        if (pv_hold_try(pv)) {
                pv_cache(pv, pindex);   /* overwrite ok (shared lock) */
                spin_unlock_shared(&pmap->pm_spin);
                *errorp = 0;
                KKASSERT(pv->pv_pmap == pmap && pv->pv_pindex == pindex);
                return(pv);     /* lock succeeded */
        }
        spin_unlock_shared(&pmap->pm_spin);
        *errorp = 1;

        return (pv);            /* lock failed */
}

/*
 * Lock a held pv, keeping the hold count
 */
static
void
_pv_lock(pv_entry_t pv PMAP_DEBUG_DECL)
{
        u_int count;

        for (;;) {
                count = pv->pv_hold;
                cpu_ccfence();
                if ((count & PV_HOLD_LOCKED) == 0) {
                        if (atomic_cmpset_int(&pv->pv_hold, count,
                                              count | PV_HOLD_LOCKED)) {
#ifdef PMAP_DEBUG
                                pv->pv_func = func;
                                pv->pv_line = lineno;
#endif
                                return;
                        }
                        continue;
                }
                tsleep_interlock(pv, 0);
                if (atomic_cmpset_int(&pv->pv_hold, count,
                                      count | PV_HOLD_WAITING)) {
#ifdef PMAP_DEBUG2
                        if (pmap_enter_debug > 0) {
                                --pmap_enter_debug;
                                kprintf("pv waiting on %s:%d\n",
                                        pv->pv_func, pv->pv_line);
                        }
#endif
                        tsleep(pv, PINTERLOCKED, "pvwait", hz);
                }
                /* retry */
        }
}

/*
 * Unlock a held and locked pv, keeping the hold count.
 */
static
void
pv_unlock(pv_entry_t pv)
{
        u_int count;

        for (;;) {
                count = pv->pv_hold;
                cpu_ccfence();
                KKASSERT((count & (PV_HOLD_LOCKED | PV_HOLD_MASK)) >=
                         (PV_HOLD_LOCKED | 1));
                if (atomic_cmpset_int(&pv->pv_hold, count,
                                      count &
                                      ~(PV_HOLD_LOCKED | PV_HOLD_WAITING))) {
                        if (count & PV_HOLD_WAITING)
                                wakeup(pv);
                        break;
                }
        }
}

/*
 * Unlock and drop a pv.  If the pv is no longer associated with a pmap
 * and the hold count drops to zero we will free it.
 *
 * Caller should not hold any spin locks.  We are protected from hold races
 * by virtue of holds only occuring only with a pmap_spin or vm_page_spin
 * lock held.  A pv cannot be located otherwise.
 */
static
void
pv_put(pv_entry_t pv)
{
#ifdef PMAP_DEBUG2
        if (pmap_enter_debug > 0) {
                --pmap_enter_debug;
                kprintf("pv_put pv=%p hold=%08x\n", pv, pv->pv_hold);
        }
#endif

        /*
         * Normal put-aways must have a pv_m associated with the pv,
         * but allow the case where the pv has been destructed due
         * to pmap_dynamic_delete.
         */
        KKASSERT(pv->pv_pmap == NULL || pv->pv_m != NULL);

        /*
         * Fast - shortcut most common condition
         */
        if (atomic_cmpset_int(&pv->pv_hold, PV_HOLD_LOCKED | 2, 1))
                return;

        /*
         * Slow
         */
        pv_unlock(pv);
        pv_drop(pv);
}

/*
 * Remove the pmap association from a pv, require that pv_m already be removed,
 * then unlock and drop the pv.  Any pte operations must have already been
 * completed.  This call may result in a last-drop which will physically free
 * the pv.
 *
 * Removing the pmap association entails an additional drop.
 *
 * pv must be exclusively locked on call and will be disposed of on return.
 */
static
void
_pv_free(pv_entry_t pv, pv_entry_t pvp PMAP_DEBUG_DECL)
{
        pmap_t pmap;

#ifdef PMAP_DEBUG
        pv->pv_func_lastfree = func;
        pv->pv_line_lastfree = lineno;
#endif
        KKASSERT(pv->pv_m == NULL);
        KKASSERT((pv->pv_hold & (PV_HOLD_LOCKED|PV_HOLD_MASK)) >=
                  (PV_HOLD_LOCKED|1));
        if ((pmap = pv->pv_pmap) != NULL) {
                spin_lock(&pmap->pm_spin);
                KKASSERT(pv->pv_pmap == pmap);
                if (pmap->pm_pvhint == pv)
                        pmap->pm_pvhint = NULL;
                pv_entry_rb_tree_RB_REMOVE(&pmap->pm_pvroot, pv);
                atomic_add_long(&pmap->pm_stats.resident_count, -1);
                pv->pv_pmap = NULL;
                pv->pv_pindex = 0;
                spin_unlock(&pmap->pm_spin);

                /*
                 * Try to shortcut three atomic ops, otherwise fall through
                 * and do it normally.  Drop two refs and the lock all in
                 * one go.
                 */
                if (pvp)
                        vm_page_unwire_quick(pvp->pv_m);
                if (atomic_cmpset_int(&pv->pv_hold, PV_HOLD_LOCKED | 2, 0)) {
#ifdef PMAP_DEBUG2
                        if (pmap_enter_debug > 0) {
                                --pmap_enter_debug;
                                kprintf("pv_free: free pv %p\n", pv);
                        }
#endif
                        zfree(pvzone, pv);
                        return;
                }
                pv_drop(pv);    /* ref for pv_pmap */
        }
        pv_unlock(pv);
        pv_drop(pv);
}

/*
 * This routine is very drastic, but can save the system
 * in a pinch.
 */
void
pmap_collect(void)
{
        int i;
        vm_page_t m;
        static int warningdone=0;

        if (pmap_pagedaemon_waken == 0)
                return;
        pmap_pagedaemon_waken = 0;
        if (warningdone < 5) {
                kprintf("pmap_collect: collecting pv entries -- "
                        "suggest increasing PMAP_SHPGPERPROC\n");
                warningdone++;
        }

        for (i = 0; i < vm_page_array_size; i++) {
                m = &vm_page_array[i];
                if (m->wire_count || m->hold_count)
                        continue;
                if (vm_page_busy_try(m, TRUE) == 0) {
                        if (m->wire_count == 0 && m->hold_count == 0) {
                                pmap_remove_all(m);
                        }
                        vm_page_wakeup(m);
                }
        }
}

/*
 * Scan the pmap for active page table entries and issue a callback.
 * The callback must dispose of pte_pv, whos PTE entry is at *ptep in
 * its parent page table.
 *
 * pte_pv will be NULL if the page or page table is unmanaged.
 * pt_pv will point to the page table page containing the pte for the page.
 *
 * NOTE! If we come across an unmanaged page TABLE (verses an unmanaged page),
 *       we pass a NULL pte_pv and we pass a pt_pv pointing to the passed
 *       process pmap's PD and page to the callback function.  This can be
 *       confusing because the pt_pv is really a pd_pv, and the target page
 *       table page is simply aliased by the pmap and not owned by it.
 *
 * It is assumed that the start and end are properly rounded to the page size.
 *
 * It is assumed that PD pages and above are managed and thus in the RB tree,
 * allowing us to use RB_SCAN from the PD pages down for ranged scans.
 */
struct pmap_scan_info {
        struct pmap *pmap;
        vm_offset_t sva;
        vm_offset_t eva;
        vm_pindex_t sva_pd_pindex;
        vm_pindex_t eva_pd_pindex;
        void (*func)(pmap_t, struct pmap_scan_info *,
                     pv_entry_t, vm_pindex_t *, pv_entry_t,
                     int, vm_offset_t,
                     pt_entry_t *, void *);
        void *arg;
        pmap_inval_bulk_t bulk_core;
        pmap_inval_bulk_t *bulk;
        int count;
        int stop;
};

static int pmap_scan_cmp(pv_entry_t pv, void *data);
static int pmap_scan_callback(pv_entry_t pv, void *data);

static void
pmap_scan(struct pmap_scan_info *info, int smp_inval)
{
        struct pmap *pmap = info->pmap;
        pv_entry_t pd_pv;       /* A page directory PV */
        pv_entry_t pt_pv;       /* A page table PV */
        pv_entry_t pte_pv;      /* A page table entry PV */
        vm_pindex_t *pte_placemark;
        vm_pindex_t *pt_placemark;
        pt_entry_t *ptep;
        pt_entry_t oldpte;
        struct pv_entry dummy_pv;

        info->stop = 0;
        if (pmap == NULL)
                return;
        if (info->sva == info->eva)
                return;
        if (smp_inval) {
                info->bulk = &info->bulk_core;
                pmap_inval_bulk_init(&info->bulk_core, pmap);
        } else {
                info->bulk = NULL;
        }

        /*
         * Hold the token for stability; if the pmap is empty we have nothing
         * to do.
         */
#if 0
        if (pmap->pm_stats.resident_count == 0) {
                return;
        }
#endif

        info->count = 0;

        /*
         * Special handling for scanning one page, which is a very common
         * operation (it is?).
         *
         * NOTE: Locks must be ordered bottom-up. pte,pt,pd,pdp,pml4
         */
        if (info->sva + PAGE_SIZE == info->eva) {
                if (info->sva >= VM_MAX_USER_ADDRESS) {
                        /*
                         * Kernel mappings do not track wire counts on
                         * page table pages and only maintain pd_pv and
                         * pte_pv levels so pmap_scan() works.
                         */
                        pt_pv = NULL;
                        pte_pv = pv_get(pmap, pmap_pte_pindex(info->sva),
                                        &pte_placemark);
                        ptep = vtopte(info->sva);
                } else {
                        /*
                         * User pages which are unmanaged will not have a
                         * pte_pv.  User page table pages which are unmanaged
                         * (shared from elsewhere) will also not have a pt_pv.
                         * The func() callback will pass both pte_pv and pt_pv
                         * as NULL in that case.
                         *
                         * We hold pte_placemark across the operation for
                         * unmanaged pages.
                         *
                         * WARNING!  We must hold pt_placemark across the
                         *           *ptep test to prevent misintepreting
                         *           a non-zero *ptep as a shared page
                         *           table page.  Hold it across the function
                         *           callback as well for SMP safety.
                         */
                        pte_pv = pv_get(pmap, pmap_pte_pindex(info->sva),
                                        &pte_placemark);
                        pt_pv = pv_get(pmap, pmap_pt_pindex(info->sva),
                                        &pt_placemark);
                        if (pt_pv == NULL) {
                                KKASSERT(pte_pv == NULL);
                                pd_pv = pv_get(pmap,
                                               pmap_pd_pindex(info->sva),
                                               NULL);
                                if (pd_pv) {
                                        ptep = pv_pte_lookup(pd_pv,
                                                    pmap_pt_index(info->sva));
                                        if (*ptep) {
                                                info->func(pmap, info,
                                                     NULL, pt_placemark,
                                                     pd_pv, 1,
                                                     info->sva, ptep,
                                                     info->arg);
                                        } else {
                                                pv_placemarker_wakeup(pmap,
                                                                  pt_placemark);
                                        }
                                        pv_put(pd_pv);
                                } else {
                                        pv_placemarker_wakeup(pmap,
                                                              pt_placemark);
                                }
                                pv_placemarker_wakeup(pmap, pte_placemark);
                                goto fast_skip;
                        }
                        ptep = pv_pte_lookup(pt_pv, pmap_pte_index(info->sva));
                }

                /*
                 * NOTE: *ptep can't be ripped out from under us if we hold
                 *       pte_pv (or pte_placemark) locked, but bits can
                 *       change.
                 */
                oldpte = *ptep;
                cpu_ccfence();
                if (oldpte == 0) {
                        KKASSERT(pte_pv == NULL);
                        pv_placemarker_wakeup(pmap, pte_placemark);
                } else if (pte_pv) {
                        KASSERT((oldpte & (pmap->pmap_bits[PG_MANAGED_IDX] |
                                           pmap->pmap_bits[PG_V_IDX])) ==
                                (pmap->pmap_bits[PG_MANAGED_IDX] |
                                 pmap->pmap_bits[PG_V_IDX]),
                            ("badA *ptep %016lx/%016lx sva %016lx pte_pv %p",
                            *ptep, oldpte, info->sva, pte_pv));
                        info->func(pmap, info, pte_pv, NULL, pt_pv, 0,
                                   info->sva, ptep, info->arg);
                } else {
                        KASSERT((oldpte & (pmap->pmap_bits[PG_MANAGED_IDX] |
                                           pmap->pmap_bits[PG_V_IDX])) ==
                            pmap->pmap_bits[PG_V_IDX],
                            ("badB *ptep %016lx/%016lx sva %016lx pte_pv NULL",
                            *ptep, oldpte, info->sva));
                        info->func(pmap, info, NULL, pte_placemark, pt_pv, 0,
                                   info->sva, ptep, info->arg);
                }
                if (pt_pv)
                        pv_put(pt_pv);
fast_skip:
                pmap_inval_bulk_flush(info->bulk);
                return;
        }

        /*
         * Nominal scan case, RB_SCAN() for PD pages and iterate from
         * there.
         *
         * WARNING! eva can overflow our standard ((N + mask) >> bits)
         *          bounds, resulting in a pd_pindex of 0.  To solve the
         *          problem we use an inclusive range.
         */
        info->sva_pd_pindex = pmap_pd_pindex(info->sva);
        info->eva_pd_pindex = pmap_pd_pindex(info->eva - PAGE_SIZE);

        if (info->sva >= VM_MAX_USER_ADDRESS) {
                /*
                 * The kernel does not currently maintain any pv_entry's for
                 * higher-level page tables.
                 */
                bzero(&dummy_pv, sizeof(dummy_pv));
                dummy_pv.pv_pindex = info->sva_pd_pindex;
                spin_lock(&pmap->pm_spin);
                while (dummy_pv.pv_pindex <= info->eva_pd_pindex) {
                        pmap_scan_callback(&dummy_pv, info);
                        ++dummy_pv.pv_pindex;
                        if (dummy_pv.pv_pindex < info->sva_pd_pindex) /*wrap*/
                                break;
                }
                spin_unlock(&pmap->pm_spin);
        } else {
                /*
                 * User page tables maintain local PML4, PDP, and PD
                 * pv_entry's at the very least.  PT pv's might be
                 * unmanaged and thus not exist.  PTE pv's might be
                 * unmanaged and thus not exist.
                 */
                spin_lock(&pmap->pm_spin);
                pv_entry_rb_tree_RB_SCAN(&pmap->pm_pvroot, pmap_scan_cmp,
                                         pmap_scan_callback, info);
                spin_unlock(&pmap->pm_spin);
        }
        pmap_inval_bulk_flush(info->bulk);
}

/*
 * WARNING! pmap->pm_spin held
 *
 * WARNING! eva can overflow our standard ((N + mask) >> bits)
 *          bounds, resulting in a pd_pindex of 0.  To solve the
 *          problem we use an inclusive range.
 */
static int
pmap_scan_cmp(pv_entry_t pv, void *data)
{
        struct pmap_scan_info *info = data;
        if (pv->pv_pindex < info->sva_pd_pindex)
                return(-1);
        if (pv->pv_pindex > info->eva_pd_pindex)
                return(1);
        return(0);
}

/*
 * pmap_scan() by PDs
 *
 * WARNING! pmap->pm_spin held
 */
static int
pmap_scan_callback(pv_entry_t pv, void *data)
{
        struct pmap_scan_info *info = data;
        struct pmap *pmap = info->pmap;
        pv_entry_t pd_pv;       /* A page directory PV */
        pv_entry_t pt_pv;       /* A page table PV */
        vm_pindex_t *pt_placemark;
        pt_entry_t *ptep;
        pt_entry_t oldpte;
        vm_offset_t sva;
        vm_offset_t eva;
        vm_offset_t va_next;
        vm_pindex_t pd_pindex;
        int error;

        /*
         * Stop if requested
         */
        if (info->stop)
                return -1;

        /*
         * Pull the PD pindex from the pv before releasing the spinlock.
         *
         * WARNING: pv is faked for kernel pmap scans.
         */
        pd_pindex = pv->pv_pindex;
        spin_unlock(&pmap->pm_spin);
        pv = NULL;      /* invalid after spinlock unlocked */

        /*
         * Calculate the page range within the PD.  SIMPLE pmaps are
         * direct-mapped for the entire 2^64 address space.  Normal pmaps
         * reflect the user and kernel address space which requires
         * cannonicalization w/regards to converting pd_pindex's back
         * into addresses.
         */
        sva = (pd_pindex - pmap_pd_pindex(0)) << PDPSHIFT;
        if ((pmap->pm_flags & PMAP_FLAG_SIMPLE) == 0 &&
            (sva & PML4_SIGNMASK)) {
                sva |= PML4_SIGNMASK;
        }
        eva = sva + NBPDP;      /* can overflow */
        if (sva < info->sva)
                sva = info->sva;
        if (eva < info->sva || eva > info->eva)
                eva = info->eva;

        /*
         * NOTE: kernel mappings do not track page table pages, only
         *       terminal pages.
         *
         * NOTE: Locks must be ordered bottom-up. pte,pt,pd,pdp,pml4.
         *       However, for the scan to be efficient we try to
         *       cache items top-down.
         */
        pd_pv = NULL;
        pt_pv = NULL;

        for (; sva < eva; sva = va_next) {
                if (info->stop)
                        break;
                if (sva >= VM_MAX_USER_ADDRESS) {
                        if (pt_pv) {
                                pv_put(pt_pv);
                                pt_pv = NULL;
                        }
                        goto kernel_skip;
                }

                /*
                 * PD cache, scan shortcut if it doesn't exist.
                 */
                if (pd_pv == NULL) {
                        pd_pv = pv_get(pmap, pmap_pd_pindex(sva), NULL);
                } else if (pd_pv->pv_pmap != pmap ||
                           pd_pv->pv_pindex != pmap_pd_pindex(sva)) {
                        pv_put(pd_pv);
                        pd_pv = pv_get(pmap, pmap_pd_pindex(sva), NULL);
                }
                if (pd_pv == NULL) {
                        va_next = (sva + NBPDP) & ~PDPMASK;
                        if (va_next < sva)
                                va_next = eva;
                        continue;
                }

                /*
                 * PT cache
                 *
                 * NOTE: The cached pt_pv can be removed from the pmap when
                 *       pmap_dynamic_delete is enabled.
                 */
                if (pt_pv && (pt_pv->pv_pmap != pmap ||
                              pt_pv->pv_pindex != pmap_pt_pindex(sva))) {
                        pv_put(pt_pv);
                        pt_pv = NULL;
                }
                if (pt_pv == NULL) {
                        pt_pv = pv_get_try(pmap, pmap_pt_pindex(sva),
                                           &pt_placemark, &error);
                        if (error) {
                                pv_put(pd_pv);  /* lock order */
                                pd_pv = NULL;
                                if (pt_pv) {
                                        pv_lock(pt_pv);
                                        pv_put(pt_pv);
                                        pt_pv = NULL;
                                } else {
                                        pv_placemarker_wait(pmap, pt_placemark);
                                }
                                va_next = sva;
                                continue;
                        }
                        /* may have to re-check later if pt_pv is NULL here */
                }

                /*
                 * If pt_pv is NULL we either have an shared page table
                 * page and must issue a callback specific to that case,
                 * or there is no page table page.
                 *
                 * Either way we can skip the page table page.
                 *
                 * WARNING! pt_pv can also be NULL due to a pv creation
                 *          race where we find it to be NULL and then
                 *          later see a pte_pv.  But its possible the pt_pv
                 *          got created inbetween the two operations, so
                 *          we must check.
                 */
                if (pt_pv == NULL) {
                        /*
                         * Possible unmanaged (shared from another pmap)
                         * page table page.
                         *
                         * WARNING!  We must hold pt_placemark across the
                         *           *ptep test to prevent misintepreting
                         *           a non-zero *ptep as a shared page
                         *           table page.  Hold it across the function
                         *           callback as well for SMP safety.
                         */
                        ptep = pv_pte_lookup(pd_pv, pmap_pt_index(sva));
                        if (*ptep & pmap->pmap_bits[PG_V_IDX]) {
                                info->func(pmap, info, NULL, pt_placemark,
                                           pd_pv, 1,
                                           sva, ptep, info->arg);
                        } else {
                                pv_placemarker_wakeup(pmap, pt_placemark);
                        }

                        /*
                         * Done, move to next page table page.
                         */
                        va_next = (sva + NBPDR) & ~PDRMASK;
                        if (va_next < sva)
                                va_next = eva;
                        continue;
                }

                /*
                 * From this point in the loop testing pt_pv for non-NULL
                 * means we are in UVM, else if it is NULL we are in KVM.
                 *
                 * 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.
                 */
kernel_skip:
                va_next = (sva + NBPDR) & ~PDRMASK;
                if (va_next < sva)
                        va_next = eva;
                if (va_next > eva)
                        va_next = eva;

                /*
                 * Scan the page table for pages.  Some pages may not be
                 * managed (might not have a pv_entry).
                 *
                 * There is no page table management for kernel pages so
                 * pt_pv will be NULL in that case, but otherwise pt_pv
                 * is non-NULL, locked, and referenced.
                 */

                /*
                 * At this point a non-NULL pt_pv means a UVA, and a NULL
                 * pt_pv means a KVA.
                 */
                if (pt_pv)
                        ptep = pv_pte_lookup(pt_pv, pmap_pte_index(sva));
                else
                        ptep = vtopte(sva);

                while (sva < va_next) {
                        pv_entry_t pte_pv;
                        vm_pindex_t *pte_placemark;

                        /*
                         * Yield every 64 pages, stop if requested.
                         */
                        if ((++info->count & 63) == 0)
                                lwkt_user_yield();
                        if (info->stop)
                                break;

                        /*
                         * We can shortcut our scan if *ptep == 0.  This is
                         * an unlocked check.
                         */
                        if (*ptep == 0) {
                                sva += PAGE_SIZE;
                                ++ptep;
                                continue;
                        }
                        cpu_ccfence();

                        /*
                         * Acquire the related pte_pv, if any.  If *ptep == 0
                         * the related pte_pv should not exist, but if *ptep
                         * is not zero the pte_pv may or may not exist (e.g.
                         * will not exist for an unmanaged page).
                         *
                         * However a multitude of races are possible here
                         * so if we cannot lock definite state we clean out
                         * our cache and break the inner while() loop to
                         * force a loop up to the top of the for().
                         *
                         * XXX unlock/relock pd_pv, pt_pv, and re-test their
                         *     validity instead of looping up?
                         */
                        pte_pv = pv_get_try(pmap, pmap_pte_pindex(sva),
                                            &pte_placemark, &error);
                        if (error) {
                                pv_put(pd_pv);          /* lock order */
                                pd_pv = NULL;
                                if (pt_pv) {
                                        pv_put(pt_pv);  /* lock order */
                                        pt_pv = NULL;
                                }
                                if (pte_pv) {           /* block */
                                        pv_lock(pte_pv);
                                        pv_put(pte_pv);
                                        pte_pv = NULL;
                                } else {
                                        pv_placemarker_wait(pmap,
                                                        pte_placemark);
                                }
                                va_next = sva;          /* retry */
                                break;
                        }

                        /*
                         * Reload *ptep after successfully locking the
                         * pindex.  If *ptep == 0 we had better NOT have a
                         * pte_pv.
                         */
                        cpu_ccfence();
                        oldpte = *ptep;
                        if (oldpte == 0) {
                                if (pte_pv) {
                                        kprintf("Unexpected non-NULL pte_pv "
                                                "%p pt_pv %p "
                                                "*ptep = %016lx/%016lx\n",
                                                pte_pv, pt_pv, *ptep, oldpte);
                                        panic("Unexpected non-NULL pte_pv");
                                } else {
                                        pv_placemarker_wakeup(pmap, pte_placemark);
                                }
                                sva += PAGE_SIZE;
                                ++ptep;
                                continue;
                        }

                        /*
                         * We can't hold pd_pv across the callback (because
                         * we don't pass it to the callback and the callback
                         * might deadlock)
                         */
                        if (pd_pv) {
                                vm_page_wire_quick(pd_pv->pv_m);
                                pv_unlock(pd_pv);
                        }

                        /*
                         * Ready for the callback.  The locked pte_pv (if any)
                         * is consumed by the callback.  pte_pv will exist if
                         * the page is managed, and will not exist if it
                         * isn't.
                         */
                        if (oldpte & pmap->pmap_bits[PG_MANAGED_IDX]) {
                                /*
                                 * Managed pte
                                 */
                                KASSERT(pte_pv &&
                                         (oldpte & pmap->pmap_bits[PG_V_IDX]),
                                    ("badC *ptep %016lx/%016lx sva %016lx "
                                    "pte_pv %p",
                                    *ptep, oldpte, sva, pte_pv));
                                /*
                                 * We must unlock pd_pv across the callback
                                 * to avoid deadlocks on any recursive
                                 * disposal.  Re-check that it still exists
                                 * after re-locking.
                                 *
                                 * Call target disposes of pte_pv and may
                                 * destroy but will not dispose of pt_pv.
                                 */
                                info->func(pmap, info, pte_pv, NULL,
                                           pt_pv, 0,
                                           sva, ptep, info->arg);
                        } else {
                                /*
                                 * Unmanaged pte
                                 *
                                 * We must unlock pd_pv across the callback
                                 * to avoid deadlocks on any recursive
                                 * disposal.  Re-check that it still exists
                                 * after re-locking.
                                 *
                                 * Call target disposes of pte_pv or
                                 * pte_placemark and may destroy but will
                                 * not dispose of pt_pv.
                                 */
                                KASSERT(pte_pv == NULL &&
                                        (oldpte & pmap->pmap_bits[PG_V_IDX]),
                                    ("badD *ptep %016lx/%016lx sva %016lx "
                                    "pte_pv %p pte_pv->pv_m %p ",
                                     *ptep, oldpte, sva,
                                     pte_pv, (pte_pv ? pte_pv->pv_m : NULL)));
                                if (pte_pv)
                                        kprintf("RaceD\n");
                                if (pte_pv) {
                                        info->func(pmap, info,
                                                   pte_pv, NULL,
                                                   pt_pv, 0,
                                                   sva, ptep, info->arg);
                                } else {
                                        info->func(pmap, info,
                                                   NULL, pte_placemark,
                                                   pt_pv, 0,
                                                   sva, ptep, info->arg);
                                }
                        }
                        if (pd_pv) {
                                pv_lock(pd_pv);
                                vm_page_unwire_quick(pd_pv->pv_m);
                                if (pd_pv->pv_pmap == NULL) {
                                        va_next = sva;          /* retry */
                                        break;
                                }
                        }

                        /*
                         * NOTE: The cached pt_pv can be removed from the
                         *       pmap when pmap_dynamic_delete is enabled,
                         *       which will cause ptep to become stale.
                         *
                         *       This also means that no pages remain under
                         *       the PT, so we can just break out of the inner
                         *       loop and let the outer loop clean everything
                         *       up.
                         */
                        if (pt_pv && pt_pv->pv_pmap != pmap)
                                break;
                        pte_pv = NULL;
                        sva += PAGE_SIZE;
                        ++ptep;
                }
        }
        if (pd_pv) {
                pv_put(pd_pv);
                pd_pv = NULL;
        }
        if (pt_pv) {
                pv_put(pt_pv);
                pt_pv = NULL;
        }
        if ((++info->count & 7) == 0)
                lwkt_user_yield();

        /*
         * Relock before returning.
         */
        spin_lock(&pmap->pm_spin);
        return (0);
}

void
pmap_remove(struct pmap *pmap, vm_offset_t sva, vm_offset_t eva)
{
        struct pmap_scan_info info;

        info.pmap = pmap;
        info.sva = sva;
        info.eva = eva;
        info.func = pmap_remove_callback;
        info.arg = NULL;
        pmap_scan(&info, 1);
#if 0
        cpu_invltlb();
        if (eva - sva < 1024*1024) {
                while (sva < eva) {
                        cpu_invlpg((void *)sva);
                        sva += PAGE_SIZE;
                }
        }
#endif
}

static void
pmap_remove_noinval(struct pmap *pmap, vm_offset_t sva, vm_offset_t eva)
{
        struct pmap_scan_info info;

        info.pmap = pmap;
        info.sva = sva;
        info.eva = eva;
        info.func = pmap_remove_callback;
        info.arg = NULL;
        pmap_scan(&info, 0);
}

static void
pmap_remove_callback(pmap_t pmap, struct pmap_scan_info *info,
                     pv_entry_t pte_pv, vm_pindex_t *pte_placemark,
                     pv_entry_t pt_pv, int sharept,
                     vm_offset_t va, pt_entry_t *ptep, void *arg __unused)
{
        pt_entry_t pte;

        if (pte_pv) {
                /*
                 * Managed entry
                 *
                 * This will also drop pt_pv's wire_count. Note that
                 * terminal pages are not wired based on mmu presence.
                 *
                 * NOTE: If this is the kernel_pmap, pt_pv can be NULL.
                 */
                KKASSERT(pte_pv->pv_m != NULL);
                pmap_remove_pv_pte(pte_pv, pt_pv, info->bulk, 2);
                pte_pv = NULL;  /* safety */

                /*
                 * Recursively destroy higher-level page tables.
                 *
                 * This is optional.  If we do not, they will still
                 * be destroyed when the process exits.
                 *
                 * NOTE: Do not destroy pv_entry's with extra hold refs,
                 *       a caller may have unlocked it and intends to
                 *       continue to use it.
                 */
                if (pmap_dynamic_delete &&
                    pt_pv &&
                    pt_pv->pv_m &&
                    pt_pv->pv_m->wire_count == 1 &&
                    (pt_pv->pv_hold & PV_HOLD_MASK) == 2 &&
                    pt_pv->pv_pindex != pmap_pml4_pindex()) {
                        if (pmap_dynamic_delete == 2)
                                kprintf("B %jd %08x\n", pt_pv->pv_pindex, pt_pv->pv_hold);
                        pv_hold(pt_pv); /* extra hold */
                        pmap_remove_pv_pte(pt_pv, NULL, info->bulk, 1);
                        pv_lock(pt_pv); /* prior extra hold + relock */
                }
        } else if (sharept == 0) {
                /*
                 * Unmanaged pte (pte_placemark is non-NULL)
                 *
                 * pt_pv's wire_count is still bumped by unmanaged pages
                 * so we must decrement it manually.
                 *
                 * We have to unwire the target page table page.
                 */
                pte = pmap_inval_bulk(info->bulk, va, ptep, 0);
                if (pte & pmap->pmap_bits[PG_W_IDX])
                        atomic_add_long(&pmap->pm_stats.wired_count, -1);
                atomic_add_long(&pmap->pm_stats.resident_count, -1);
                if (vm_page_unwire_quick(pt_pv->pv_m))
                        panic("pmap_remove: insufficient wirecount");
                pv_placemarker_wakeup(pmap, pte_placemark);
        } else {
                /*
                 * Unmanaged page table (pt, pd, or pdp. Not pte) for
                 * a shared page table.
                 *
                 * pt_pv is actually the pd_pv for our pmap (not the shared
                 * object pmap).
                 *
                 * We have to unwire the target page table page and we
                 * have to unwire our page directory page.
                 *
                 * It is unclear how we can invalidate a segment so we
                 * invalidate -1 which invlidates the tlb.
                 */
                pte = pmap_inval_bulk(info->bulk, (vm_offset_t)-1, ptep, 0);
                atomic_add_long(&pmap->pm_stats.resident_count, -1);
                KKASSERT((pte & pmap->pmap_bits[PG_DEVICE_IDX]) == 0);
                if (vm_page_unwire_quick(PHYS_TO_VM_PAGE(pte & PG_FRAME)))
                        panic("pmap_remove: shared pgtable1 bad wirecount");
                if (vm_page_unwire_quick(pt_pv->pv_m))
                        panic("pmap_remove: shared pgtable2 bad wirecount");
                pv_placemarker_wakeup(pmap, pte_placemark);
        }
}

/*
 * Removes this physical page from all physical maps in which it resides.
 * Reflects back modify bits to the pager.
 *
 * This routine may not be called from an interrupt.
 */
static
void
pmap_remove_all(vm_page_t m)
{
        pv_entry_t pv;
        pmap_inval_bulk_t bulk;

        if (!pmap_initialized /* || (m->flags & PG_FICTITIOUS)*/)
                return;

        vm_page_spin_lock(m);
        while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
                KKASSERT(pv->pv_m == m);
                if (pv_hold_try(pv)) {
                        vm_page_spin_unlock(m);
                } else {
                        vm_page_spin_unlock(m);
                        pv_lock(pv);
                        pv_put(pv);
                        vm_page_spin_lock(m);
                        continue;
                }
                KKASSERT(pv->pv_pmap && pv->pv_m == m);

                /*
                 * Holding no spinlocks, pv is locked.  Once we scrap
                 * pv we can no longer use it as a list iterator (but
                 * we are doing a TAILQ_FIRST() so we are ok).
                 */
                pmap_inval_bulk_init(&bulk, pv->pv_pmap);
                pmap_remove_pv_pte(pv, NULL, &bulk, 2);
                pv = NULL;      /* safety */
                pmap_inval_bulk_flush(&bulk);
                vm_page_spin_lock(m);
        }
        KKASSERT((m->flags & (PG_MAPPED|PG_WRITEABLE)) == 0);
        vm_page_spin_unlock(m);
}

/*
 * Removes the page from a particular pmap
 */
void
pmap_remove_specific(pmap_t pmap, vm_page_t m)
{
        pv_entry_t pv;
        pmap_inval_bulk_t bulk;

        if (!pmap_initialized)
                return;

again:
        vm_page_spin_lock(m);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                if (pv->pv_pmap != pmap)
                        continue;
                KKASSERT(pv->pv_m == m);
                if (pv_hold_try(pv)) {
                        vm_page_spin_unlock(m);
                } else {
                        vm_page_spin_unlock(m);
                        pv_lock(pv);
                        pv_put(pv);
                        goto again;
                }
                KKASSERT(pv->pv_pmap == pmap && pv->pv_m == m);

                /*
                 * Holding no spinlocks, pv is locked.  Once gone it can't
                 * be used as an iterator.  In fact, because we couldn't
                 * necessarily lock it atomically it may have moved within
                 * the list and ALSO cannot be used as an iterator.
                 */
                pmap_inval_bulk_init(&bulk, pv->pv_pmap);
                pmap_remove_pv_pte(pv, NULL, &bulk, 2);
                pv = NULL;      /* safety */
                pmap_inval_bulk_flush(&bulk);
                goto again;
        }
        vm_page_spin_unlock(m);
}

/*
 * Set the physical protection on the specified range of this map
 * as requested.  This function is typically only used for debug watchpoints
 * and COW pages.
 *
 * This function may not be called from an interrupt if the map is
 * not the kernel_pmap.
 *
 * NOTE!  For shared page table pages we just unmap the page.
 */
void
pmap_protect(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
{
        struct pmap_scan_info info;
        /* JG review for NX */

        if (pmap == NULL)
                return;
        if ((prot & (VM_PROT_READ | VM_PROT_EXECUTE)) == VM_PROT_NONE) {
                pmap_remove(pmap, sva, eva);
                return;
        }
        if (prot & VM_PROT_WRITE)
                return;
        info.pmap = pmap;
        info.sva = sva;
        info.eva = eva;
        info.func = pmap_protect_callback;
        info.arg = &prot;
        pmap_scan(&info, 1);
}

static
void
pmap_protect_callback(pmap_t pmap, struct pmap_scan_info *info,
                      pv_entry_t pte_pv, vm_pindex_t *pte_placemark,
                      pv_entry_t pt_pv, int sharept,
                      vm_offset_t va, pt_entry_t *ptep, void *arg __unused)
{
        pt_entry_t pbits;
        pt_entry_t cbits;
        pt_entry_t pte;
        vm_page_t m;

again:
        pbits = *ptep;
        cbits = pbits;
        if (pte_pv) {
                KKASSERT(pte_pv->pv_m != NULL);
                m = NULL;
                if (pbits & pmap->pmap_bits[PG_A_IDX]) {
                        if ((pbits & pmap->pmap_bits[PG_DEVICE_IDX]) == 0) {
                                m = PHYS_TO_VM_PAGE(pbits & PG_FRAME);
                                KKASSERT(m == pte_pv->pv_m);
                                vm_page_flag_set(m, PG_REFERENCED);
                        }
                        cbits &= ~pmap->pmap_bits[PG_A_IDX];
                }
                if (pbits & pmap->pmap_bits[PG_M_IDX]) {
                        if (pmap_track_modified(pte_pv->pv_pindex)) {
                                if ((pbits & pmap->pmap_bits[PG_DEVICE_IDX]) == 0) {
                                        if (m == NULL) {
                                                m = PHYS_TO_VM_PAGE(pbits &
                                                                    PG_FRAME);
                                        }
                                        vm_page_dirty(m);
                                }
                                cbits &= ~pmap->pmap_bits[PG_M_IDX];
                        }
                }
        } else if (sharept) {
                /*
                 * Unmanaged page table, pt_pv is actually the pd_pv
                 * for our pmap (not the object's shared pmap).
                 *
                 * When asked to protect something in a shared page table
                 * page we just unmap the page table page.  We have to
                 * invalidate the tlb in this situation.
                 *
                 * XXX Warning, shared page tables will not be used for
                 * OBJT_DEVICE or OBJT_MGTDEVICE (PG_FICTITIOUS) mappings
                 * so PHYS_TO_VM_PAGE() should be safe here.
                 */
                pte = pmap_inval_smp(pmap, (vm_offset_t)-1, 1, ptep, 0);
                if (vm_page_unwire_quick(PHYS_TO_VM_PAGE(pte & PG_FRAME)))
                        panic("pmap_protect: pgtable1 pg bad wirecount");
                if (vm_page_unwire_quick(pt_pv->pv_m))
                        panic("pmap_protect: pgtable2 pg bad wirecount");
                ptep = NULL;
        }
        /* else unmanaged page, adjust bits, no wire changes */

        if (ptep) {
                cbits &= ~pmap->pmap_bits[PG_RW_IDX];
#ifdef PMAP_DEBUG2
                if (pmap_enter_debug > 0) {
                        --pmap_enter_debug;
                        kprintf("pmap_protect va=%lx ptep=%p pte_pv=%p "
                                "pt_pv=%p cbits=%08lx\n",
                                va, ptep, pte_pv,
                                pt_pv, cbits
                        );
                }
#endif
                if (pbits != cbits) {
                        vm_offset_t xva;

                        xva = (sharept) ? (vm_offset_t)-1 : va;
                        if (!pmap_inval_smp_cmpset(pmap, xva,
                                                   ptep, pbits, cbits)) {
                                goto again;
                        }
                }
        }
        if (pte_pv)
                pv_put(pte_pv);
        else
                pv_placemarker_wakeup(pmap, pte_placemark);
}

/*
 * Insert the vm_page (m) at the virtual address (va), replacing any prior
 * mapping at that address.  Set protection and wiring as requested.
 *
 * If entry is non-NULL we check to see if the SEG_SIZE optimization is
 * possible.  If it is we enter the page into the appropriate shared pmap
 * hanging off the related VM object instead of the passed pmap, then we
 * share the page table page from the VM object's pmap into the current pmap.
 *
 * NOTE: This routine MUST insert the page into the pmap now, it cannot
 *       lazy-evaluate.
 *
 * NOTE: If (m) is PG_UNMANAGED it may also be a temporary fake vm_page_t.
 *       never record it.
 */
void
pmap_enter(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
           boolean_t wired, vm_map_entry_t entry)
{
        pv_entry_t pt_pv;       /* page table */
        pv_entry_t pte_pv;      /* page table entry */
        vm_pindex_t *pte_placemark;
        pt_entry_t *ptep;
        vm_paddr_t opa;
        pt_entry_t origpte, newpte;
        vm_paddr_t pa;

        if (pmap == NULL)
                return;
        va = trunc_page(va);
#ifdef PMAP_DIAGNOSTIC
        if (va >= KvaEnd)
                panic("pmap_enter: toobig");
        if ((va >= UPT_MIN_ADDRESS) && (va < UPT_MAX_ADDRESS))
                panic("pmap_enter: invalid to pmap_enter page table "
                      "pages (va: 0x%lx)", va);
#endif
        if (va < UPT_MAX_ADDRESS && pmap == &kernel_pmap) {
                kprintf("Warning: pmap_enter called on UVA with "
                        "kernel_pmap\n");
#ifdef DDB
                db_print_backtrace();
#endif
        }
        if (va >= UPT_MAX_ADDRESS && pmap != &kernel_pmap) {
                kprintf("Warning: pmap_enter called on KVA without"
                        "kernel_pmap\n");
#ifdef DDB
                db_print_backtrace();
#endif
        }

        /*
         * Get locked PV entries for our new page table entry (pte_pv or
         * pte_placemark) and for its parent page table (pt_pv).  We need
         * the parent so we can resolve the location of the ptep.
         *
         * Only hardware MMU actions can modify the ptep out from
         * under us.
         *
         * if (m) is fictitious or unmanaged we do not create a managing
         * pte_pv for it.  Any pre-existing page's management state must
         * match (avoiding code complexity).
         *
         * If the pmap is still being initialized we assume existing
         * page tables.
         *
         * Kernel mapppings do not track page table pages (i.e. pt_pv).
         *
         * WARNING! If replacing a managed mapping with an unmanaged mapping
         *          pte_pv will wind up being non-NULL and must be handled
         *          below.
         */
        if (pmap_initialized == FALSE) {
                pte_pv = NULL;
                pt_pv = NULL;
                pte_placemark = NULL;
                ptep = vtopte(va);
                origpte = *ptep;
        } else if (m->flags & (/*PG_FICTITIOUS |*/ PG_UNMANAGED)) { /* XXX */
                pte_pv = pv_get(pmap, pmap_pte_pindex(va), &pte_placemark);
                KKASSERT(pte_pv == NULL);
                if (va >= VM_MAX_USER_ADDRESS) {
                        pt_pv = NULL;
                        ptep = vtopte(va);
                } else {
                        pt_pv = pmap_allocpte_seg(pmap, pmap_pt_pindex(va),
                                                  NULL, entry, va);
                        ptep = pv_pte_lookup(pt_pv, pmap_pte_index(va));
                }
                origpte = *ptep;
                cpu_ccfence();
                KASSERT(origpte == 0 ||
                         (origpte & pmap->pmap_bits[PG_MANAGED_IDX]) == 0,
                         ("Invalid PTE 0x%016jx @ 0x%016jx\n", origpte, va));
        } else {
                if (va >= VM_MAX_USER_ADDRESS) {
                        /*
                         * Kernel map, pv_entry-tracked.
                         */
                        pt_pv = NULL;
                        pte_pv = pmap_allocpte(pmap, pmap_pte_pindex(va), NULL);
                        ptep = vtopte(va);
                } else {
                        /*
                         * User map
                         */
                        pte_pv = pmap_allocpte_seg(pmap, pmap_pte_pindex(va),
                                                   &pt_pv, entry, va);
                        ptep = pv_pte_lookup(pt_pv, pmap_pte_index(va));
                }
                pte_placemark = NULL;   /* safety */
                origpte = *ptep;
                cpu_ccfence();
                KASSERT(origpte == 0 ||
                         (origpte & pmap->pmap_bits[PG_MANAGED_IDX]),
                         ("Invalid PTE 0x%016jx @ 0x%016jx\n", origpte, va));
        }

        pa = VM_PAGE_TO_PHYS(m);
        opa = origpte & PG_FRAME;

        /*
         * Calculate the new PTE.  Note that pte_pv alone does not mean
         * the new pte_pv is managed, it could exist because the old pte
         * was managed even if the new one is not.
         */
        newpte = (pt_entry_t)(pa | pte_prot(pmap, prot) |
                 pmap->pmap_bits[PG_V_IDX] | pmap->pmap_bits[PG_A_IDX]);
        if (wired)
                newpte |= pmap->pmap_bits[PG_W_IDX];
        if (va < VM_MAX_USER_ADDRESS)
                newpte |= pmap->pmap_bits[PG_U_IDX];
        if (pte_pv && (m->flags & (/*PG_FICTITIOUS |*/ PG_UNMANAGED)) == 0)
                newpte |= pmap->pmap_bits[PG_MANAGED_IDX];
//      if (pmap == &kernel_pmap)
//              newpte |= pgeflag;
        newpte |= pmap->pmap_cache_bits[m->pat_mode];
        if (m->flags & PG_FICTITIOUS)
                newpte |= pmap->pmap_bits[PG_DEVICE_IDX];

        /*
         * It is possible for multiple faults to occur in threaded
         * environments, the existing pte might be correct.
         */
        if (((origpte ^ newpte) &
            ~(pt_entry_t)(pmap->pmap_bits[PG_M_IDX] |
                          pmap->pmap_bits[PG_A_IDX])) == 0) {
                goto done;
        }

        /*
         * Ok, either the address changed or the protection or wiring
         * changed.
         *
         * Clear the current entry, interlocking the removal.  For managed
         * pte's this will also flush the modified state to the vm_page.
         * Atomic ops are mandatory in order to ensure that PG_M events are
         * not lost during any transition.
         *
         * WARNING: The caller has busied the new page but not the original
         *          vm_page which we are trying to replace.  Because we hold
         *          the pte_pv lock, but have not busied the page, PG bits
         *          can be cleared out from under us.
         */
        if (opa) {
                if (origpte & pmap->pmap_bits[PG_MANAGED_IDX]) {
                        /*
                         * Old page was managed.  Expect pte_pv to exist.
                         * (it might also exist if the old page was unmanaged).
                         *
                         * NOTE: pt_pv won't exist for a kernel page
                         *       (managed or otherwise).
                         *
                         * NOTE: We may be reusing the pte_pv so we do not
                         *       destroy it in pmap_remove_pv_pte().
                         */
                        KKASSERT(pte_pv && pte_pv->pv_m);
                        if (prot & VM_PROT_NOSYNC) {
                                pmap_remove_pv_pte(pte_pv, pt_pv, NULL, 0);
                        } else {
                                pmap_inval_bulk_t bulk;

                                pmap_inval_bulk_init(&bulk, pmap);
                                pmap_remove_pv_pte(pte_pv, pt_pv, &bulk, 0);
                                pmap_inval_bulk_flush(&bulk);
                        }
                        pmap_remove_pv_page(pte_pv);
                        /* will either set pte_pv->pv_m or pv_free() later */
                } else {
                        /*
                         * Old page was not managed.  If we have a pte_pv
                         * it better not have a pv_m assigned to it.  If the
                         * new page is managed the pte_pv will be destroyed
                         * near the end (we need its interlock).
                         *
                         * NOTE: We leave the wire count on the PT page
                         *       intact for the followup enter, but adjust
                         *       the wired-pages count on the pmap.
                         */
                        KKASSERT(pte_pv == NULL);
                        if (prot & VM_PROT_NOSYNC) {
                                /*
                                 * NOSYNC (no mmu sync) requested.
                                 */
                                (void)pte_load_clear(ptep);
                                cpu_invlpg((void *)va);
                        } else {
                                /*
                                 * Nominal SYNC
                                 */
                                pmap_inval_smp(pmap, va, 1, ptep, 0);
                        }

                        /*
                         * We must adjust pm_stats manually for unmanaged
                         * pages.
                         */
                        if (pt_pv) {
                                atomic_add_long(&pmap->pm_stats.
                                                resident_count, -1);
                        }
                        if (origpte & pmap->pmap_bits[PG_W_IDX]) {
                                atomic_add_long(&pmap->pm_stats.
                                                wired_count, -1);
                        }
                }
                KKASSERT(*ptep == 0);
        }

#ifdef PMAP_DEBUG2
        if (pmap_enter_debug > 0) {
                --pmap_enter_debug;
                kprintf("pmap_enter: va=%lx m=%p origpte=%lx newpte=%lx ptep=%p"
                        " pte_pv=%p pt_pv=%p opa=%lx prot=%02x\n",
                        va, m,
                        origpte, newpte, ptep,
                        pte_pv, pt_pv, opa, prot);
        }
#endif

        if ((newpte & pmap->pmap_bits[PG_MANAGED_IDX]) == 0) {
                /*
                 * Entering an unmanaged page.  We must wire the pt_pv unless
                 * we retained the wiring from an unmanaged page we had
                 * removed (if we retained it via pte_pv that will go away
                 * soon).
                 */
                if (pt_pv && (opa == 0 ||
                              (origpte & pmap->pmap_bits[PG_MANAGED_IDX]))) {
                        vm_page_wire_quick(pt_pv->pv_m);
                }
                if (wired)
                        atomic_add_long(&pmap->pm_stats.wired_count, 1);

                /*
                 * Unmanaged pages need manual resident_count tracking.
                 */
                if (pt_pv) {
                        atomic_add_long(&pt_pv->pv_pmap->pm_stats.
                                        resident_count, 1);
                }
                if (newpte & pmap->pmap_bits[PG_RW_IDX])
                        vm_page_flag_set(m, PG_WRITEABLE);
        } else {
                /*
                 * Entering a managed page.  Our pte_pv takes care of the
                 * PT wiring, so if we had removed an unmanaged page before
                 * we must adjust.
                 *
                 * We have to take care of the pmap wired count ourselves.
                 *
                 * Enter on the PV list if part of our managed memory.
                 */
                KKASSERT(pte_pv && (pte_pv->pv_m == NULL || pte_pv->pv_m == m));
                vm_page_spin_lock(m);
                pte_pv->pv_m = m;
                pmap_page_stats_adding(m);
                TAILQ_INSERT_TAIL(&m->md.pv_list, pte_pv, pv_list);
                vm_page_flag_set(m, PG_MAPPED);
                if (newpte & pmap->pmap_bits[PG_RW_IDX])
                        vm_page_flag_set(m, PG_WRITEABLE);
                vm_page_spin_unlock(m);

                if (pt_pv && opa &&
                    (origpte & pmap->pmap_bits[PG_MANAGED_IDX]) == 0) {
                        vm_page_unwire_quick(pt_pv->pv_m);
                }

                /*
                 * Adjust pmap wired pages count for new entry.
                 */
                if (wired) {
                        atomic_add_long(&pte_pv->pv_pmap->pm_stats.
                                        wired_count, 1);
                }
        }

        /*
         * Kernel VMAs (pt_pv == NULL) require pmap invalidation interlocks.
         *
         * User VMAs do not because those will be zero->non-zero, so no
         * stale entries to worry about at this point.
         *
         * For KVM there appear to still be issues.  Theoretically we
         * should be able to scrap the interlocks entirely but we
         * get crashes.
         */
        if ((prot & VM_PROT_NOSYNC) == 0 && pt_pv == NULL) {
                pmap_inval_smp(pmap, va, 1, ptep, newpte);
        } else {
                origpte = atomic_swap_long(ptep, newpte);
                if (origpte & pmap->pmap_bits[PG_M_IDX]) {
                        kprintf("pmap [M] race @ %016jx\n", va);
                        atomic_set_long(ptep, pmap->pmap_bits[PG_M_IDX]);
                }
                if (pt_pv == NULL)
                        cpu_invlpg((void *)va);
        }

        /*
         * Cleanup
         */
done:
        KKASSERT((newpte & pmap->pmap_bits[PG_MANAGED_IDX]) == 0 ||
                 (m->flags & PG_MAPPED));

        /*
         * Cleanup the pv entry, allowing other accessors.  If the new page
         * is not managed but we have a pte_pv (which was locking our
         * operation), we can free it now.  pte_pv->pv_m should be NULL.
         */
        if (pte_pv && (newpte & pmap->pmap_bits[PG_MANAGED_IDX]) == 0) {
                pv_free(pte_pv, pt_pv);
        } else if (pte_pv) {
                pv_put(pte_pv);
        } else if (pte_placemark) {
                pv_placemarker_wakeup(pmap, pte_placemark);
        }
        if (pt_pv)
                pv_put(pt_pv);
}

/*
 * This code works like pmap_enter() but assumes VM_PROT_READ and not-wired.
 * This code also assumes that the pmap has no pre-existing entry for this
 * VA.
 *
 * This code currently may only be used on user pmaps, not kernel_pmap.
 */
void
pmap_enter_quick(pmap_t pmap, vm_offset_t va, vm_page_t m)
{
        pmap_enter(pmap, va, m, VM_PROT_READ, FALSE, NULL);
}

/*
 * Make a temporary mapping for a physical address.  This is only intended
 * to be used for panic dumps.
 *
 * The caller is responsible for calling smp_invltlb().
 */
void *
pmap_kenter_temporary(vm_paddr_t pa, long i)
{
        pmap_kenter_quick((vm_offset_t)crashdumpmap + (i * PAGE_SIZE), pa);
        return ((void *)crashdumpmap);
}

#define MAX_INIT_PT (96)

/*
 * This routine preloads the ptes for a given object into the specified pmap.
 * This eliminates the blast of soft faults on process startup and
 * immediately after an mmap.
 */
static int pmap_object_init_pt_callback(vm_page_t p, void *data);

void
pmap_object_init_pt(pmap_t pmap, vm_offset_t addr, vm_prot_t prot,
                    vm_object_t object, vm_pindex_t pindex,
                    vm_size_t size, int limit)
{
        struct rb_vm_page_scan_info info;
        struct lwp *lp;
        vm_size_t psize;

        /*
         * We can't preinit if read access isn't set or there is no pmap
         * or object.
         */
        if ((prot & VM_PROT_READ) == 0 || pmap == NULL || object == NULL)
                return;

        /*
         * We can't preinit if the pmap is not the current pmap
         */
        lp = curthread->td_lwp;
        if (lp == NULL || pmap != vmspace_pmap(lp->lwp_vmspace))
                return;

        /*
         * Misc additional checks
         */
        psize = x86_64_btop(size);

        if ((object->type != OBJT_VNODE) ||
                ((limit & MAP_PREFAULT_PARTIAL) && (psize > MAX_INIT_PT) &&
                        (object->resident_page_count > MAX_INIT_PT))) {
                return;
        }

        if (pindex + psize > object->size) {
                if (object->size < pindex)
                        return;           
                psize = object->size - pindex;
        }

        if (psize == 0)
                return;

        /*
         * If everything is segment-aligned do not pre-init here.  Instead
         * allow the normal vm_fault path to pass a segment hint to
         * pmap_enter() which will then use an object-referenced shared
         * page table page.
         */
        if ((addr & SEG_MASK) == 0 &&
            (ctob(psize) & SEG_MASK) == 0 &&
            (ctob(pindex) & SEG_MASK) == 0) {
                return;
        }

        /*
         * Use a red-black scan to traverse the requested range and load
         * any valid pages found into the pmap.
         *
         * We cannot safely scan the object's memq without holding the
         * object token.
         */
        info.start_pindex = pindex;
        info.end_pindex = pindex + psize - 1;
        info.limit = limit;
        info.mpte = NULL;
        info.addr = addr;
        info.pmap = pmap;

        vm_object_hold_shared(object);
        vm_page_rb_tree_RB_SCAN(&object->rb_memq, rb_vm_page_scancmp,
                                pmap_object_init_pt_callback, &info);
        vm_object_drop(object);
}

static
int
pmap_object_init_pt_callback(vm_page_t p, void *data)
{
        struct rb_vm_page_scan_info *info = data;
        vm_pindex_t rel_index;

        /*
         * don't allow an madvise to blow away our really
         * free pages allocating pv entries.
         */
        if ((info->limit & MAP_PREFAULT_MADVISE) &&
                vmstats.v_free_count < vmstats.v_free_reserved) {
                    return(-1);
        }

        /*
         * Ignore list markers and ignore pages we cannot instantly
         * busy (while holding the object token).
         */
        if (p->flags & PG_MARKER)
                return 0;
        if (vm_page_busy_try(p, TRUE))
                return 0;
        if (((p->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
            (p->flags & PG_FICTITIOUS) == 0) {
                if ((p->queue - p->pc) == PQ_CACHE)
                        vm_page_deactivate(p);
                rel_index = p->pindex - info->start_pindex;
                pmap_enter_quick(info->pmap,
                                 info->addr + x86_64_ptob(rel_index), p);
        }
        vm_page_wakeup(p);
        lwkt_yield();
        return(0);
}

/*
 * Return TRUE if the pmap is in shape to trivially pre-fault the specified
 * address.
 *
 * Returns FALSE if it would be non-trivial or if a pte is already loaded
 * into the slot.
 *
 * XXX This is safe only because page table pages are not freed.
 */
int
pmap_prefault_ok(pmap_t pmap, vm_offset_t addr)
{
        pt_entry_t *pte;

        /*spin_lock(&pmap->pm_spin);*/
        if ((pte = pmap_pte(pmap, addr)) != NULL) {
                if (*pte & pmap->pmap_bits[PG_V_IDX]) {
                        /*spin_unlock(&pmap->pm_spin);*/
                        return FALSE;
                }
        }
        /*spin_unlock(&pmap->pm_spin);*/
        return TRUE;
}

/*
 * Change the wiring attribute for a pmap/va pair.  The mapping must already
 * exist in the pmap.  The mapping may or may not be managed.  The wiring in
 * the page is not changed, the page is returned so the caller can adjust
 * its wiring (the page is not locked in any way).
 *
 * Wiring is not a hardware characteristic so there is no need to invalidate
 * TLB.  However, in an SMP environment we must use a locked bus cycle to
 * update the pte (if we are not using the pmap_inval_*() API that is)...
 * it's ok to do this for simple wiring changes.
 */
vm_page_t
pmap_unwire(pmap_t pmap, vm_offset_t va)
{
        pt_entry_t *ptep;
        pv_entry_t pt_pv;
        vm_paddr_t pa;
        vm_page_t m;

        if (pmap == NULL)
                return NULL;

        /*
         * Assume elements in the kernel pmap are stable
         */
        if (pmap == &kernel_pmap) {
                if (pmap_pt(pmap, va) == 0)
                        return NULL;
                ptep = pmap_pte_quick(pmap, va);
                if (pmap_pte_v(pmap, ptep)) {
                        if (pmap_pte_w(pmap, ptep))
                                atomic_add_long(&pmap->pm_stats.wired_count,-1);
                        atomic_clear_long(ptep, pmap->pmap_bits[PG_W_IDX]);
                        pa = *ptep & PG_FRAME;
                        m = PHYS_TO_VM_PAGE(pa);
                } else {
                        m = NULL;
                }
        } else {
                /*
                 * We can only [un]wire pmap-local pages (we cannot wire
                 * shared pages)
                 */
                pt_pv = pv_get(pmap, pmap_pt_pindex(va), NULL);
                if (pt_pv == NULL)
                        return NULL;

                ptep = pv_pte_lookup(pt_pv, pmap_pte_index(va));
                if ((*ptep & pmap->pmap_bits[PG_V_IDX]) == 0) {
                        pv_put(pt_pv);
                        return NULL;
                }

                if (pmap_pte_w(pmap, ptep)) {
                        atomic_add_long(&pt_pv->pv_pmap->pm_stats.wired_count,
                                        -1);
                }
                /* XXX else return NULL so caller doesn't unwire m ? */

                atomic_clear_long(ptep, pmap->pmap_bits[PG_W_IDX]);

                pa = *ptep & PG_FRAME;
                m = PHYS_TO_VM_PAGE(pa);        /* held by wired count */
                pv_put(pt_pv);
        }
        return m;
}

/*
 * 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)
{
}       

/*
 * pmap_zero_page:
 *
 *      Zero the specified physical page.
 *
 *      This function may be called from an interrupt and no locking is
 *      required.
 */
void
pmap_zero_page(vm_paddr_t phys)
{
        vm_offset_t va = PHYS_TO_DMAP(phys);

        pagezero((void *)va);
}

/*
 * pmap_zero_page:
 *
 *      Zero part of a physical page by mapping it into memory and clearing
 *      its contents with bzero.
 *
 *      off and size may not cover an area beyond a single hardware page.
 */
void
pmap_zero_page_area(vm_paddr_t phys, int off, int size)
{
        vm_offset_t virt = PHYS_TO_DMAP(phys);

        bzero((char *)virt + off, size);
}

/*
 * pmap_copy_page:
 *
 *      Copy the physical page from the source PA to the target PA.
 *      This function may be called from an interrupt.  No locking
 *      is required.
 */
void
pmap_copy_page(vm_paddr_t src, vm_paddr_t dst)
{
        vm_offset_t src_virt, dst_virt;

        src_virt = PHYS_TO_DMAP(src);
        dst_virt = PHYS_TO_DMAP(dst);
        bcopy((void *)src_virt, (void *)dst_virt, PAGE_SIZE);
}

/*
 * pmap_copy_page_frag:
 *
 *      Copy the physical page from the source PA to the target PA.
 *      This function may be called from an interrupt.  No locking
 *      is required.
 */
void
pmap_copy_page_frag(vm_paddr_t src, vm_paddr_t dst, size_t bytes)
{
        vm_offset_t src_virt, dst_virt;

        src_virt = PHYS_TO_DMAP(src);
        dst_virt = PHYS_TO_DMAP(dst);

        bcopy((char *)src_virt + (src & PAGE_MASK),
              (char *)dst_virt + (dst & PAGE_MASK),
              bytes);
}

/*
 * 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)
{
        pv_entry_t pv;
        int loops = 0;

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

        vm_page_spin_lock(m);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                if (pv->pv_pmap == pmap) {
                        vm_page_spin_unlock(m);
                        return TRUE;
                }
                loops++;
                if (loops >= 16)
                        break;
        }
        vm_page_spin_unlock(m);
        return (FALSE);
}

/*
 * Remove all pages from specified address space this aids process exit
 * speeds.  Also, this code may be special cased for the current process
 * only.
 */
void
pmap_remove_pages(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
{
        pmap_remove_noinval(pmap, sva, eva);
        cpu_invltlb();
}

/*
 * pmap_testbit tests bits in pte's note that the testbit/clearbit
 * routines are inline, and a lot of things compile-time evaluate.
 */
static
boolean_t
pmap_testbit(vm_page_t m, int bit)
{
        pv_entry_t pv;
        pt_entry_t *pte;
        pmap_t pmap;

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

        if (TAILQ_FIRST(&m->md.pv_list) == NULL)
                return FALSE;
        vm_page_spin_lock(m);
        if (TAILQ_FIRST(&m->md.pv_list) == NULL) {
                vm_page_spin_unlock(m);
                return FALSE;
        }

        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {

#if defined(PMAP_DIAGNOSTIC)
                if (pv->pv_pmap == NULL) {
                        kprintf("Null pmap (tb) at pindex: %"PRIu64"\n",
                            pv->pv_pindex);
                        continue;
                }
#endif
                pmap = pv->pv_pmap;

                /*
                 * If the bit being tested is the modified bit, then
                 * mark clean_map and ptes as never
                 * modified.
                 *
                 * WARNING!  Because we do not lock the pv, *pte can be in a
                 *           state of flux.  Despite this the value of *pte
                 *           will still be related to the vm_page in some way
                 *           because the pv cannot be destroyed as long as we
                 *           hold the vm_page spin lock.
                 */
                if (bit == PG_A_IDX || bit == PG_M_IDX) {
                                //& (pmap->pmap_bits[PG_A_IDX] | pmap->pmap_bits[PG_M_IDX])) {
                        if (!pmap_track_modified(pv->pv_pindex))
                                continue;
                }

                pte = pmap_pte_quick(pv->pv_pmap, pv->pv_pindex << PAGE_SHIFT);
                if (*pte & pmap->pmap_bits[bit]) {
                        vm_page_spin_unlock(m);
                        return TRUE;
                }
        }
        vm_page_spin_unlock(m);
        return (FALSE);
}

/*
 * This routine is used to modify bits in ptes.  Only one bit should be
 * specified.  PG_RW requires special handling.
 *
 * Caller must NOT hold any spin locks
 */
static __inline
void
pmap_clearbit(vm_page_t m, int bit_index)
{
        pv_entry_t pv;
        pt_entry_t *pte;
        pt_entry_t pbits;
        pmap_t pmap;

        if (!pmap_initialized || (m->flags & PG_FICTITIOUS)) {
                if (bit_index == PG_RW_IDX)
                        vm_page_flag_clear(m, PG_WRITEABLE);
                return;
        }

        /*
         * PG_M or PG_A case
         *
         * Loop over all current mappings setting/clearing as appropos If
         * setting RO do we need to clear the VAC?
         *
         * NOTE: When clearing PG_M we could also (not implemented) drop
         *       through to the PG_RW code and clear PG_RW too, forcing
         *       a fault on write to redetect PG_M for virtual kernels, but
         *       it isn't necessary since virtual kernels invalidate the
         *       pte when they clear the VPTE_M bit in their virtual page
         *       tables.
         *
         * NOTE: Does not re-dirty the page when clearing only PG_M.
         *
         * NOTE: Because we do not lock the pv, *pte can be in a state of
         *       flux.  Despite this the value of *pte is still somewhat
         *       related while we hold the vm_page spin lock.
         *
         *       *pte can be zero due to this race.  Since we are clearing
         *       bits we basically do no harm when this race occurs.
         */
        if (bit_index != PG_RW_IDX) {
                vm_page_spin_lock(m);
                TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
#if defined(PMAP_DIAGNOSTIC)
                        if (pv->pv_pmap == NULL) {
                                kprintf("Null pmap (cb) at pindex: %"PRIu64"\n",
                                    pv->pv_pindex);
                                continue;
                        }
#endif
                        pmap = pv->pv_pmap;
                        pte = pmap_pte_quick(pv->pv_pmap,
                                             pv->pv_pindex << PAGE_SHIFT);
                        pbits = *pte;
                        if (pbits & pmap->pmap_bits[bit_index])
                                atomic_clear_long(pte, pmap->pmap_bits[bit_index]);
                }
                vm_page_spin_unlock(m);
                return;
        }

        /*
         * Clear PG_RW.  Also clears PG_M and marks the page dirty if PG_M
         * was set.
         */
restart:
        vm_page_spin_lock(m);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                /*
                 * don't write protect pager mappings
                 */
                if (!pmap_track_modified(pv->pv_pindex))
                        continue;

#if defined(PMAP_DIAGNOSTIC)
                if (pv->pv_pmap == NULL) {
                        kprintf("Null pmap (cb) at pindex: %"PRIu64"\n",
                                pv->pv_pindex);
                        continue;
                }
#endif
                pmap = pv->pv_pmap;

                /*
                 * Skip pages which do not have PG_RW set.
                 */
                pte = pmap_pte_quick(pv->pv_pmap, pv->pv_pindex << PAGE_SHIFT);
                if ((*pte & pmap->pmap_bits[PG_RW_IDX]) == 0)
                        continue;

                /*
                 * We must lock the PV to be able to safely test the pte.
                 */
                if (pv_hold_try(pv)) {
                        vm_page_spin_unlock(m);
                } else {
                        vm_page_spin_unlock(m);
                        pv_lock(pv);    /* held, now do a blocking lock */
                        pv_put(pv);
                        goto restart;
                }

                /*
                 * Reload pte after acquiring pv.
                 */
                pte = pmap_pte_quick(pv->pv_pmap, pv->pv_pindex << PAGE_SHIFT);
#if 0
                if ((*pte & pmap->pmap_bits[PG_RW_IDX]) == 0) {
                        pv_put(pv);
                        goto restart;
                }
#endif

                KKASSERT(pv->pv_pmap == pmap && pv->pv_m == m);
                for (;;) {
                        pt_entry_t nbits;

                        pbits = *pte;
                        cpu_ccfence();
                        nbits = pbits & ~(pmap->pmap_bits[PG_RW_IDX] |
                                          pmap->pmap_bits[PG_M_IDX]);
                        if (pmap_inval_smp_cmpset(pmap,
                                     ((vm_offset_t)pv->pv_pindex << PAGE_SHIFT),
                                     pte, pbits, nbits)) {
                                break;
                        }
                        cpu_pause();
                }

                /*
                 * If PG_M was found to be set while we were clearing PG_RW
                 * we also clear PG_M (done above) and mark the page dirty.
                 * Callers expect this behavior.
                 *
                 * we lost pv so it cannot be used as an iterator.  In fact,
                 * because we couldn't necessarily lock it atomically it may
                 * have moved within the list and ALSO cannot be used as an
                 * iterator.
                 */
                vm_page_spin_lock(m);
                if (pbits & pmap->pmap_bits[PG_M_IDX])
                        vm_page_dirty(m);
                vm_page_spin_unlock(m);
                pv_put(pv);
                goto restart;
        }
        if (bit_index == PG_RW_IDX)
                vm_page_flag_clear(m, PG_WRITEABLE);
        vm_page_spin_unlock(m);
}

/*
 * Lower the permission for all mappings to a given page.
 *
 * Page must be busied by caller.  Because page is busied by caller this
 * should not be able to race a pmap_enter().
 */
void
pmap_page_protect(vm_page_t m, vm_prot_t prot)
{
        /* JG NX support? */
        if ((prot & VM_PROT_WRITE) == 0) {
                if (prot & (VM_PROT_READ | VM_PROT_EXECUTE)) {
                        /*
                         * NOTE: pmap_clearbit(.. PG_RW) also clears
                         *       the PG_WRITEABLE flag in (m).
                         */
                        pmap_clearbit(m, PG_RW_IDX);
                } else {
                        pmap_remove_all(m);
                }
        }
}

vm_paddr_t
pmap_phys_address(vm_pindex_t ppn)
{
        return (x86_64_ptob(ppn));
}

/*
 * 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.
 *
 * This routine may not block.
 */
int
pmap_ts_referenced(vm_page_t m)
{
        pv_entry_t pv;
        pt_entry_t *pte;
        pmap_t pmap;
        int rtval = 0;

        if (!pmap_initialized || (m->flags & PG_FICTITIOUS))
                return (rtval);

        vm_page_spin_lock(m);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                if (!pmap_track_modified(pv->pv_pindex))
                        continue;
                pmap = pv->pv_pmap;
                pte = pmap_pte_quick(pv->pv_pmap, pv->pv_pindex << PAGE_SHIFT);
                if (pte && (*pte & pmap->pmap_bits[PG_A_IDX])) {
                        atomic_clear_long(pte, pmap->pmap_bits[PG_A_IDX]);
                        rtval++;
                        if (rtval > 4)
                                break;
                }
        }
        vm_page_spin_unlock(m);
        return (rtval);
}

/*
 *      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)
{
        boolean_t res;

        res = pmap_testbit(m, PG_M_IDX);
        return (res);
}

/*
 *      Clear the modify bits on the specified physical page.
 */
void
pmap_clear_modify(vm_page_t m)
{
        pmap_clearbit(m, PG_M_IDX);
}

/*
 *      pmap_clear_reference:
 *
 *      Clear the reference bit on the specified physical page.
 */
void
pmap_clear_reference(vm_page_t m)
{
        pmap_clearbit(m, PG_A_IDX);
}

/*
 * Miscellaneous support routines follow
 */

static
void
i386_protection_init(void)
{
        uint64_t *kp;
        int prot;

        /*
         * NX supported? (boot time loader.conf override only)
         */
        TUNABLE_INT_FETCH("machdep.pmap_nx_enable", &pmap_nx_enable);
        if (pmap_nx_enable == 0 || (amd_feature & AMDID_NX) == 0)
                pmap_bits_default[PG_NX_IDX] = 0;

        /*
         * 0 is basically read-only access, but also set the NX (no-execute)
         * bit when VM_PROT_EXECUTE is not specified.
         */
        kp = protection_codes;
        for (prot = 0; prot < PROTECTION_CODES_SIZE; prot++) {
                switch (prot) {
                case VM_PROT_NONE | VM_PROT_NONE | VM_PROT_NONE:
                        /*
                         * This case handled elsewhere
                         */
                        *kp++ = 0;
                        break;
                case VM_PROT_READ | VM_PROT_NONE | VM_PROT_NONE:
                        /*
                         * Read-only is 0|NX
                         */
                        *kp++ = pmap_bits_default[PG_NX_IDX];
                        break;
                case VM_PROT_READ | VM_PROT_NONE | VM_PROT_EXECUTE:
                case VM_PROT_NONE | VM_PROT_NONE | VM_PROT_EXECUTE:
                        /*
                         * Execute requires read access
                         */
                        *kp++ = 0;
                        break;
                case VM_PROT_NONE | VM_PROT_WRITE | VM_PROT_NONE:
                case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_NONE:
                        /*
                         * Write without execute is RW|NX
                         */
                        *kp++ = pmap_bits_default[PG_RW_IDX] |
                                pmap_bits_default[PG_NX_IDX];
                        break;
                case VM_PROT_READ | VM_PROT_WRITE | VM_PROT_EXECUTE:
                case VM_PROT_NONE | VM_PROT_WRITE | VM_PROT_EXECUTE:
                        /*
                         * Write with execute is RW
                         */
                        *kp++ = pmap_bits_default[PG_RW_IDX];
                        break;
                }
        }
}

/*
 * 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.
 *
 * NOTE: We can't use pgeflag unless we invalidate the pages one at
 *       a time.
 *
 * NOTE: The PAT attributes {WRITE_BACK, WRITE_THROUGH, UNCACHED, UNCACHEABLE}
 *       work whether the cpu supports PAT or not.  The remaining PAT
 *       attributes {WRITE_PROTECTED, WRITE_COMBINING} only work if the cpu
 *       supports PAT.
 */
void *
pmap_mapdev(vm_paddr_t pa, vm_size_t size)
{
        return(pmap_mapdev_attr(pa, size, PAT_WRITE_BACK));
}

void *
pmap_mapdev_uncacheable(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));
}

/*
 * 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;
        pt_entry_t *pte;
        vm_size_t tmpsize;

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

        va = kmem_alloc_nofault(&kernel_map, size, VM_SUBSYS_MAPDEV, PAGE_SIZE);
        if (va == 0)
                panic("pmap_mapdev: Couldn't alloc kernel virtual memory");

        pa = pa & ~PAGE_MASK;
        for (tmpva = va, tmpsize = size; tmpsize > 0;) {
                pte = vtopte(tmpva);
                *pte = pa |
                    kernel_pmap.pmap_bits[PG_RW_IDX] |
                    kernel_pmap.pmap_bits[PG_V_IDX] | /* pgeflag | */
                    kernel_pmap.pmap_cache_bits[mode];
                tmpsize -= PAGE_SIZE;
                tmpva += PAGE_SIZE;
                pa += PAGE_SIZE;
        }
        pmap_invalidate_range(&kernel_pmap, va, va + size);
        pmap_invalidate_cache_range(va, va + size);

        return ((void *)(va + offset));
}

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

        base = va & ~PAGE_MASK;
        offset = va & PAGE_MASK;
        size = roundup(offset + size, PAGE_SIZE);
        pmap_qremove(va, size >> PAGE_SHIFT);
        kmem_free(&kernel_map, base, size);
}

/*
 * Sets the memory attribute for the specified page.
 */
void
pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
{

    m->pat_mode = ma;

    /*
     * If "m" is a normal page, update its direct mapping.  This update
     * can be relied upon to perform any cache operations that are
     * required for data coherence.
     */
    if ((m->flags & PG_FICTITIOUS) == 0)
        pmap_change_attr(PHYS_TO_DMAP(VM_PAGE_TO_PHYS(m)), 1, m->pat_mode);
}

/*
 * Change the PAT attribute on an existing kernel memory map.  Caller
 * must ensure that the virtual memory in question is not accessed
 * during the adjustment.
 */
void
pmap_change_attr(vm_offset_t va, vm_size_t count, int mode)
{
        pt_entry_t *pte;
        vm_offset_t base;
        int changed = 0;

        if (va == 0)
                panic("pmap_change_attr: va is NULL");
        base = trunc_page(va);

        while (count) {
                pte = vtopte(va);
                *pte = (*pte & ~(pt_entry_t)(kernel_pmap.pmap_cache_mask)) |
                       kernel_pmap.pmap_cache_bits[mode];
                --count;
                va += PAGE_SIZE;
        }

        changed = 1;    /* XXX: not optimal */

        /*
         * Flush CPU caches if required to make sure any data isn't cached that
         * shouldn't be, etc.
         */
        if (changed) {
                pmap_invalidate_range(&kernel_pmap, base, va);
                pmap_invalidate_cache_range(base, va);
        }
}

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

        if (ptep && (pte = *ptep) != 0) {
                vm_offset_t pa;

                val = MINCORE_INCORE;
                if ((pte & pmap->pmap_bits[PG_MANAGED_IDX]) == 0)
                        goto done;

                pa = pte & PG_FRAME;

                if (pte & pmap->pmap_bits[PG_DEVICE_IDX])
                        m = NULL;
                else
                        m = PHYS_TO_VM_PAGE(pa);

                /*
                 * Modified by us
                 */
                if (pte & pmap->pmap_bits[PG_M_IDX])
                        val |= MINCORE_MODIFIED|MINCORE_MODIFIED_OTHER;
                /*
                 * Modified by someone
                 */
                else if (m && (m->dirty || pmap_is_modified(m)))
                        val |= MINCORE_MODIFIED_OTHER;
                /*
                 * Referenced by us
                 */
                if (pte & pmap->pmap_bits[PG_A_IDX])
                        val |= MINCORE_REFERENCED|MINCORE_REFERENCED_OTHER;

                /*
                 * Referenced by someone
                 */
                else if (m && ((m->flags & PG_REFERENCED) ||
                                pmap_ts_referenced(m))) {
                        val |= MINCORE_REFERENCED_OTHER;
                        vm_page_flag_set(m, PG_REFERENCED);
                }
        } 
done:

        return val;
}

/*
 * Replace p->p_vmspace with a new one.  If adjrefs is non-zero the new
 * vmspace will be ref'd and the old one will be deref'd.
 *
 * The vmspace for all lwps associated with the process will be adjusted
 * and cr3 will be reloaded if any lwp is the current lwp.
 *
 * The process must hold the vmspace->vm_map.token for oldvm and newvm
 */
void
pmap_replacevm(struct proc *p, struct vmspace *newvm, int adjrefs)
{
        struct vmspace *oldvm;
        struct lwp *lp;

        oldvm = p->p_vmspace;
        if (oldvm != newvm) {
                if (adjrefs)
                        vmspace_ref(newvm);
                p->p_vmspace = newvm;
                KKASSERT(p->p_nthreads == 1);
                lp = RB_ROOT(&p->p_lwp_tree);
                pmap_setlwpvm(lp, newvm);
                if (adjrefs)
                        vmspace_rel(oldvm);
        }
}

/*
 * Set the vmspace for a LWP.  The vmspace is almost universally set the
 * same as the process vmspace, but virtual kernels need to swap out contexts
 * on a per-lwp basis.
 *
 * Caller does not necessarily hold any vmspace tokens.  Caller must control
 * the lwp (typically be in the context of the lwp).  We use a critical
 * section to protect against statclock and hardclock (statistics collection).
 */
void
pmap_setlwpvm(struct lwp *lp, struct vmspace *newvm)
{
        struct vmspace *oldvm;
        struct pmap *pmap;

        oldvm = lp->lwp_vmspace;

        if (oldvm != newvm) {
                crit_enter();
                KKASSERT((newvm->vm_refcnt & VM_REF_DELETED) == 0);
                lp->lwp_vmspace = newvm;
                if (curthread->td_lwp == lp) {
                        pmap = vmspace_pmap(newvm);
                        ATOMIC_CPUMASK_ORBIT(pmap->pm_active, mycpu->gd_cpuid);
                        if (pmap->pm_active_lock & CPULOCK_EXCL)
                                pmap_interlock_wait(newvm);
#if defined(SWTCH_OPTIM_STATS)
                        tlb_flush_count++;
#endif
                        if (pmap->pmap_bits[TYPE_IDX] == REGULAR_PMAP) {
                                curthread->td_pcb->pcb_cr3 = vtophys(pmap->pm_pml4);
                        } else if (pmap->pmap_bits[TYPE_IDX] == EPT_PMAP) {
                                curthread->td_pcb->pcb_cr3 = KPML4phys;
                        } else {
                                panic("pmap_setlwpvm: unknown pmap type\n");
                        }
                        load_cr3(curthread->td_pcb->pcb_cr3);
                        pmap = vmspace_pmap(oldvm);
                        ATOMIC_CPUMASK_NANDBIT(pmap->pm_active,
                                               mycpu->gd_cpuid);
                }
                crit_exit();
        }
}

/*
 * Called when switching to a locked pmap, used to interlock against pmaps
 * undergoing modifications to prevent us from activating the MMU for the
 * target pmap until all such modifications have completed.  We have to do
 * this because the thread making the modifications has already set up its
 * SMP synchronization mask.
 *
 * This function cannot sleep!
 *
 * No requirements.
 */
void
pmap_interlock_wait(struct vmspace *vm)
{
        struct pmap *pmap = &vm->vm_pmap;

        if (pmap->pm_active_lock & CPULOCK_EXCL) {
                crit_enter();
                KKASSERT(curthread->td_critcount >= 2);
                DEBUG_PUSH_INFO("pmap_interlock_wait");
                while (pmap->pm_active_lock & CPULOCK_EXCL) {
                        cpu_ccfence();
                        lwkt_process_ipiq();
                }
                DEBUG_POP_INFO();
                crit_exit();
        }
}

vm_offset_t
pmap_addr_hint(vm_object_t obj, vm_offset_t addr, vm_size_t size)
{

        if ((obj == NULL) || (size < NBPDR) ||
            ((obj->type != OBJT_DEVICE) && (obj->type != OBJT_MGTDEVICE))) {
                return addr;
        }

        addr = roundup2(addr, NBPDR);
        return addr;
}

/*
 * Used by kmalloc/kfree, page already exists at va
 */
vm_page_t
pmap_kvtom(vm_offset_t va)
{
        pt_entry_t *ptep = vtopte(va);

        KKASSERT((*ptep & kernel_pmap.pmap_bits[PG_DEVICE_IDX]) == 0);
        return(PHYS_TO_VM_PAGE(*ptep & PG_FRAME));
}

/*
 * Initialize machine-specific shared page directory support.  This
 * is executed when a VM object is created.
 */
void
pmap_object_init(vm_object_t object)
{
        object->md.pmap_rw = NULL;
        object->md.pmap_ro = NULL;
}

/*
 * Clean up machine-specific shared page directory support.  This
 * is executed when a VM object is destroyed.
 */
void
pmap_object_free(vm_object_t object)
{
        pmap_t pmap;

        if ((pmap = object->md.pmap_rw) != NULL) {
                object->md.pmap_rw = NULL;
                pmap_remove_noinval(pmap,
                                  VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS);
                CPUMASK_ASSZERO(pmap->pm_active);
                pmap_release(pmap);
                pmap_puninit(pmap);
                kfree(pmap, M_OBJPMAP);
        }
        if ((pmap = object->md.pmap_ro) != NULL) {
                object->md.pmap_ro = NULL;
                pmap_remove_noinval(pmap,
                                  VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS);
                CPUMASK_ASSZERO(pmap->pm_active);
                pmap_release(pmap);
                pmap_puninit(pmap);
                kfree(pmap, M_OBJPMAP);
        }
}

/*
 * pmap_pgscan_callback - Used by pmap_pgscan to acquire the related
 * VM page and issue a pginfo->callback.
 *
 * We are expected to dispose of any non-NULL pte_pv.
 */
static
void
pmap_pgscan_callback(pmap_t pmap, struct pmap_scan_info *info,
                      pv_entry_t pte_pv, vm_pindex_t *pte_placemark,
                      pv_entry_t pt_pv, int sharept,
                      vm_offset_t va, pt_entry_t *ptep, void *arg)
{
        struct pmap_pgscan_info *pginfo = arg;
        vm_page_t m;

        if (pte_pv) {
                /*
                 * Try to busy the page while we hold the pte_pv locked.
                 */
                KKASSERT(pte_pv->pv_m);
                m = PHYS_TO_VM_PAGE(*ptep & PG_FRAME);
                if (vm_page_busy_try(m, TRUE) == 0) {
                        if (m == PHYS_TO_VM_PAGE(*ptep & PG_FRAME)) {
                                /*
                                 * The callback is issued with the pte_pv
                                 * unlocked and put away, and the pt_pv
                                 * unlocked.
                                 */
                                pv_put(pte_pv);
                                if (pt_pv) {
                                        vm_page_wire_quick(pt_pv->pv_m);
                                        pv_unlock(pt_pv);
                                }
                                if (pginfo->callback(pginfo, va, m) < 0)
                                        info->stop = 1;
                                if (pt_pv) {
                                        pv_lock(pt_pv);
                                        vm_page_unwire_quick(pt_pv->pv_m);
                                }
                        } else {
                                vm_page_wakeup(m);
                                pv_put(pte_pv);
                        }
                } else {
                        ++pginfo->busycount;
                        pv_put(pte_pv);
                }
        } else {
                /*
                 * Shared page table or unmanaged page (sharept or !sharept)
                 */
                pv_placemarker_wakeup(pmap, pte_placemark);
        }
}

void
pmap_pgscan(struct pmap_pgscan_info *pginfo)
{
        struct pmap_scan_info info;

        pginfo->offset = pginfo->beg_addr;
        info.pmap = pginfo->pmap;
        info.sva = pginfo->beg_addr;
        info.eva = pginfo->end_addr;
        info.func = pmap_pgscan_callback;
        info.arg = pginfo;
        pmap_scan(&info, 0);
        if (info.stop == 0)
                pginfo->offset = pginfo->end_addr;
}

/*
 * Wait for a placemarker that we do not own to clear.  The placemarker
 * in question is not necessarily set to the pindex we want, we may have
 * to wait on the element because we want to reserve it ourselves.
 *
 * NOTE: PM_PLACEMARK_WAKEUP sets a bit which is already set in
 *       PM_NOPLACEMARK, so it does not interfere with placemarks
 *       which have already been woken up.
 */
static
void
pv_placemarker_wait(pmap_t pmap, vm_pindex_t *pmark)
{
        if (*pmark != PM_NOPLACEMARK) {
                atomic_set_long(pmark, PM_PLACEMARK_WAKEUP);
                tsleep_interlock(pmark, 0);
                if (*pmark != PM_NOPLACEMARK)
                        tsleep(pmark, PINTERLOCKED, "pvplw", 0);
        }
}

/*
 * Wakeup a placemarker that we own.  Replace the entry with
 * PM_NOPLACEMARK and issue a wakeup() if necessary.
 */
static
void
pv_placemarker_wakeup(pmap_t pmap, vm_pindex_t *pmark)
{
        vm_pindex_t pindex;

        pindex = atomic_swap_long(pmark, PM_NOPLACEMARK);
        KKASSERT(pindex != PM_NOPLACEMARK);
        if (pindex & PM_PLACEMARK_WAKEUP)
                wakeup(pmark);
}