Merge branch 'vendor/TCSH'

[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) 2011-2019 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.
 *
 * Some notes:
 *      - The 'M'odified bit is only applicable to terminal PTEs.
 *
 *      - The 'U'ser access bit can be set for higher-level PTEs as
 *        long as it isn't set for terminal PTEs for pages we don't
 *        want user access to.
 */

#if 0 /* JG */
#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/thread2.h>
#include <sys/spinlock2.h>
#include <vm/vm_page2.h>

#include <machine/cputypes.h>
#include <machine/cpu.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 <ddb/ddb.h>

#define PMAP_KEEP_PDIRS

#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];

/*
 * Backing scan macros.  Note that in the use case 'ipte' is only a tentitive
 * value and must be validated by a pmap_inval_smp_cmpset*() or equivalent
 * function.
 *
 * NOTE: cpu_ccfence() is required to prevent excessive optmization of
 *       of the (ipte) variable.
 *
 * NOTE: We don't bother locking the backing object if it isn't mapped
 *       to anything (backing_list is empty).
 *
 * NOTE: For now guarantee an interlock via iobj->backing_lk if the
 *       object exists and do not shortcut the lock by checking to see
 *       if the list is empty first.
 */
#define PMAP_PAGE_BACKING_SCAN(m, match_pmap, ipmap, iptep, ipte, iva)  \
        if (m->object) {                                                \
                vm_object_t iobj = m->object;                           \
                vm_map_backing_t iba, next_ba;                          \
                struct pmap *ipmap;                                     \
                pt_entry_t ipte;                                        \
                pt_entry_t *iptep;                                      \
                vm_offset_t iva;                                        \
                vm_pindex_t ipindex_start;                              \
                vm_pindex_t ipindex_end;                                \
                                                                        \
                lockmgr(&iobj->backing_lk, LK_SHARED);                  \
                next_ba = TAILQ_FIRST(&iobj->backing_list);             \
                while ((iba = next_ba) != NULL) {                       \
                        next_ba = TAILQ_NEXT(iba, entry);               \
                        ipmap = iba->pmap;                              \
                        if (match_pmap && ipmap != match_pmap)          \
                                continue;                               \
                        ipindex_start = iba->offset >> PAGE_SHIFT;      \
                        ipindex_end = ipindex_start +                   \
                                  ((iba->end - iba->start) >> PAGE_SHIFT); \
                        if (m->pindex < ipindex_start ||                \
                            m->pindex >= ipindex_end) {                 \
                                continue;                               \
                        }                                               \
                        iva = iba->start +                              \
                              ((m->pindex - ipindex_start) << PAGE_SHIFT); \
                        iptep = pmap_pte(ipmap, iva);                   \
                        if (iptep == NULL)                              \
                                continue;                               \
                        ipte = *iptep;                                  \
                        cpu_ccfence();                                  \
                        if (m->phys_addr != (ipte & PG_FRAME))          \
                                continue;                               \

#define PMAP_PAGE_BACKING_RETRY                                         \
                        {                                               \
                                next_ba = iba;                          \
                                continue;                               \
                        }                                               \

#define PMAP_PAGE_BACKING_DONE                                          \
                }                                                       \
                lockmgr(&iobj->backing_lk, LK_RELEASE);                 \
        }                                                               \

struct pmap kernel_pmap;
struct pmap iso_pmap;

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 */
vm_offset_t DMapMaxAddress;
/* Has pmap_init completed? */
__read_frequently static boolean_t pmap_initialized = FALSE;
//static int pgeflag;           /* PG_G or-in */
uint64_t PatMsr;

static int ndmpdp;
static vm_paddr_t dmaplimit;
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
 */
__read_mostly static vm_zone_t pvzone;
__read_mostly static int pmap_pagedaemon_waken = 0;
static struct vm_zone pvzone_store;
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
 */
__read_frequently 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");
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");
int pmap_lock_delay = 100;
SYSCTL_INT(_machdep, OID_AUTO, pmap_lock_delay, CTLFLAG_RW,
    &pmap_lock_delay, 0, "Spin loops");
static int meltdown_mitigation = -1;
TUNABLE_INT("machdep.meltdown_mitigation", &meltdown_mitigation);
SYSCTL_INT(_machdep, OID_AUTO, meltdown_mitigation, CTLFLAG_RW,
    &meltdown_mitigation, 0, "Userland pmap isolation");

static int pmap_nx_enable = -1;         /* -1 = auto */
/* needs manual TUNABLE in early probe, see below */
SYSCTL_INT(_machdep, OID_AUTO, pmap_nx_enable, CTLFLAG_RD,
    &pmap_nx_enable, 0,
    "no-execute support (0=disabled, 1=w/READ, 2=w/READ & WRITE)");

static int pmap_pv_debug = 50;
SYSCTL_INT(_machdep, OID_AUTO, pmap_pv_debug, CTLFLAG_RW,
    &pmap_pv_debug, 0, "");

static long vm_pmap_pv_entries;
SYSCTL_LONG(_vm, OID_AUTO, pmap_pv_entries, CTLFLAG_RD,
    &vm_pmap_pv_entries, 0, "");

/* 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);
extern uint32_t std_fuwordadd32 (volatile uint32_t *base, uint32_t v);
extern uint64_t std_fuwordadd64 (volatile uint64_t *base, uint64_t v);

#if 0
static void pv_hold(pv_entry_t pv);
#endif
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 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, int clrpgbits);
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,
                      vm_pindex_t *pte_placemark, pv_entry_t pt_pv,
                      vm_offset_t va, pt_entry_t *ptep, void *arg __unused);
static void pmap_protect_callback(pmap_t pmap, struct pmap_scan_info *info,
                      vm_pindex_t *pte_placemark, pv_entry_t pt_pv,
                      vm_offset_t va, pt_entry_t *ptep, void *arg __unused);

static void x86_64_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 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);

/*
 * Keep track of pages in the pmap.  The procedure is handed
 * the vm_page->md.pmap_count value prior to an increment or
 * decrement.
 *
 *      t_arm           - Active real memory
 *      t_avm           - Active virtual memory
 *      t_armshr        - Active real memory that is also shared
 *      t_avmshr        - Active virtual memory that is also shared
 *
 * NOTE: At the moment t_avm is effectively just the same as t_arm.
 */
static __inline
void
pmap_page_stats_adding(long prev_count)
{
        globaldata_t gd = mycpu;

        if (prev_count == 0) {
                ++gd->gd_vmtotal.t_arm;
                ++gd->gd_vmtotal.t_avm;
        } else if (prev_count == 1) {
                ++gd->gd_vmtotal.t_armshr;
                ++gd->gd_vmtotal.t_avmshr;
        } else {
                ++gd->gd_vmtotal.t_avmshr;
        }
}

static __inline
void
pmap_page_stats_deleting(long prev_count)
{
        globaldata_t gd = mycpu;

        if (prev_count == 1) {
                --gd->gd_vmtotal.t_arm;
                --gd->gd_vmtotal.t_avm;
        } else if (prev_count == 2) {
                --gd->gd_vmtotal.t_armshr;
                --gd->gd_vmtotal.t_avmshr;
        } else {
                --gd->gd_vmtotal.t_avmshr;
        }
}

/*
 * We have removed a managed pte.  The page might not be hard or soft-busied
 * at this point so we have to be careful.
 *
 * If advanced mode is enabled we can clear PG_MAPPED/WRITEABLE only if
 * MAPPEDMULTI is not set.  This must be done atomically against possible
 * concurrent pmap_enter()s occurring at the same time.  If MULTI is set
 * then the kernel may have to call vm_page_protect() later on to clean
 * the bits up.  This is particularly important for kernel_map/kernel_object
 * mappings due to the expense of scanning the kernel_object's vm_backing's.
 *
 * If advanced mode is not enabled we update our tracking counts and
 * synchronize PG_MAPPED/WRITEABLE later on in pmap_mapped_sync().
 */
static __inline
void
pmap_removed_pte(vm_page_t m, pt_entry_t pte)
{
#ifdef PMAP_ADVANCED
        int flags;
        int nflags;

        flags = m->flags;
        cpu_ccfence();
        while ((flags & PG_MAPPEDMULTI) == 0) {
                nflags = flags & ~(PG_MAPPED | PG_WRITEABLE);
                if (atomic_fcmpset_int(&m->flags, &flags, nflags))
                        break;
        }
#else
        if (pte & pmap->pmap_bits[PG_RW_IDX])
                atomic_add_long(&p->md.writeable_count, -1);
        pmap_page_stats_deleting(atomic_fetchadd_long(&p->md.pmap_count, -1));
#endif
}

/*
 * 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;
}

/*
 * 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));
}

/*
 * 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.
 * We also cache the PTE layer to (hopefully) improve relative lookup
 * speeds.
 *
 * 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(pmap_t pmap, pv_entry_t pv, vm_pindex_t pindex)
{
        if (pindex < pmap_pt_pindex(0)) {
                ;
        } else if (pindex < pmap_pd_pindex(0)) {
                pmap->pm_pvhint_pt = pv;
        }
}

/*
 * Locate the requested pt_entry
 */
static __inline
pv_entry_t
pv_entry_lookup(pmap_t pmap, vm_pindex_t pindex)
{
        pv_entry_t pv;

        if (pindex < pmap_pt_pindex(0))
                return NULL;
#if 1
        if (pindex < pmap_pd_pindex(0))
                pv = pmap->pm_pvhint_pt;
        else
                pv = NULL;
        cpu_ccfence();
        if (pv == NULL || pv->pv_pmap != pmap) {
                pv = pv_entry_rb_tree_RB_LOOKUP(&pmap->pm_pvroot, pindex);
                if (pv)
                        pv_cache(pmap, pv, pindex);
        } else if (pv->pv_pindex != pindex) {
                pv = pv_entry_rb_tree_RB_LOOKUP_REL(&pmap->pm_pvroot,
                                                    pindex, pv);
                if (pv)
                        pv_cache(pmap, pv, pindex);
        }
#else
        pv = pv_entry_rb_tree_RB_LOOKUP(&pmap->pm_pvroot, pindex);
#endif
        return pv;
}

/*
 * 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);
}

/*
 * 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));
}

/*
 * 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));
}

/*
 * Returns the physical address translation from va for a user address.
 * (vm_paddr_t)-1 is returned on failure.
 */
vm_paddr_t
uservtophys(vm_offset_t va)
{
        uint64_t mask = ((1ul << (NPTEPGSHIFT + NPDEPGSHIFT +
                                  NPDPEPGSHIFT + NPML4EPGSHIFT)) - 1);
        vm_paddr_t pa;
        pt_entry_t pte;
        pmap_t pmap;

        pmap = vmspace_pmap(mycpu->gd_curthread->td_lwp->lwp_vmspace);
        pa = (vm_paddr_t)-1;
        if (va < VM_MAX_USER_ADDRESS) {
                pte = kreadmem64(PTmap + ((va >> PAGE_SHIFT) & mask));
                if (pte & pmap->pmap_bits[PG_V_IDX])
                        pa = (pte & PG_FRAME) | (va & PAGE_MASK);
        }
        return pa;
}

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;
        long nkpd_phys;
        int j;

        /*
         * We are running (mostly) V=P at this point
         *
         * Calculate how many 1GB PD entries in our PDP pages are needed
         * for the DMAP.  This is only allocated if the system does not
         * support 1GB pages.  Otherwise ndmpdp is simply a count of
         * the number of 1G terminal entries in our PDP pages are needed.
         *
         * NOTE: Maxmem is in pages
         */
        ndmpdp = (ptoa(Maxmem) + NBPDP - 1) >> PDPSHIFT;
        if (ndmpdp < 4)         /* Minimum 4GB of dirmap */
                ndmpdp = 4;
        KKASSERT(ndmpdp <= NDMPML4E * NPML4EPG);
        DMapMaxAddress = DMAP_MIN_ADDRESS +
                         ((ndmpdp * NPDEPG) << PDRSHIFT);

        /*
         * Starting at KERNBASE - map all 2G worth of page table pages.
         * KERNBASE is offset -2G from the end of kvm.  This will accomodate
         * all KVM allocations above KERNBASE, including the SYSMAPs below.
         *
         * We do this by allocating 2*512 PT pages.  Each PT page can map
         * 2MB, for 2GB total.
         */
        nkpt_base = (NPDPEPG - KPDPI) * NPTEPG; /* typically 2 x 512 */

        /*
         * Starting at the beginning of kvm (VM_MIN_KERNEL_ADDRESS),
         * Calculate how many page table pages we need to preallocate
         * for early vm_map allocations.
         *
         * A few extra won't hurt, they will get used up in the running
         * system.
         *
         * vm_page array
         * initial pventry's
         */
        nkpt_phys = (Maxmem * sizeof(struct vm_page) + NBPDR - 1) / NBPDR;
        nkpt_phys += (Maxmem * sizeof(struct pv_entry) + NBPDR - 1) / NBPDR;
        nkpt_phys += 128;       /* a few extra */

        /*
         * The highest value nkpd_phys can be set to is
         * NKPDPE - (NPDPEPG - KPDPI) (i.e. NKPDPE - 2).
         *
         * Doing so would cause all PD pages to be pre-populated for
         * a maximal KVM space (approximately 16*512 pages, or 32MB.
         * We can save memory by not doing this.
         */
        nkpd_phys = (nkpt_phys + NPDPEPG - 1) / NPDPEPG;

        /*
         * Allocate pages
         *
         * Normally NKPML4E=1-16 (1-16 kernel PDP page)
         * Normally NKPDPE= NKPML4E*512-1 (511 min kernel PD pages)
         *
         * Only allocate enough PD pages
         * NOTE: We allocate all kernel PD pages up-front, typically
         *       ~511G of KVM, requiring 511 PD pages.
         */
        KPTbase = allocpages(firstaddr, nkpt_base);     /* KERNBASE to end */
        KPTphys = allocpages(firstaddr, nkpt_phys);     /* KVA start */
        KPML4phys = allocpages(firstaddr, 1);           /* recursive PML4 map */
        KPDPphys = allocpages(firstaddr, NKPML4E);      /* kernel PDP pages */
        KPDphys = allocpages(firstaddr, nkpd_phys);     /* kernel PD pages */

        /*
         * Alloc PD pages for the area starting at KERNBASE.
         */
        KPDbase = allocpages(firstaddr, NPDPEPG - KPDPI);

        /*
         * Stuff for our DMAP.  Use 2MB pages even when 1GB pages
         * are available in order to allow APU code to adjust page
         * attributes on a fixed grain (see pmap_change_attr()).
         */
        DMPDPphys = allocpages(firstaddr, NDMPML4E);
#if 1
        DMPDphys = allocpages(firstaddr, ndmpdp);
#else
        if ((amd_feature & AMDID_PAGE1GB) == 0)
                DMPDphys = allocpages(firstaddr, ndmpdp);
#endif
        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];
        }

        /*
         * Load PD addresses into the PDP pages for primary KVA space to
         * cover existing page tables.  PD's for KERNBASE are handled in
         * the next loop.
         *
         * expected to pre-populate all of its PDs.  See NKPDPE in vmparam.h.
         */
        for (i = 0; i < nkpd_phys; i++) {
                ((pdp_entry_t *)KPDPphys)[NKPML4E * NPDPEPG - NKPDPE + i] =
                                KPDphys + (i << PAGE_SHIFT);
                ((pdp_entry_t *)KPDPphys)[NKPML4E * NPDPEPG - NKPDPE + i] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_A_IDX];
        }

        /*
         * Load PDs for KERNBASE to the end
         */
        i = (NKPML4E - 1) * NPDPEPG + KPDPI;
        for (j = 0; j < NPDPEPG - KPDPI; ++j) {
                ((pdp_entry_t *)KPDPphys)[i + j] =
                                KPDbase + (j << PAGE_SHIFT);
                ((pdp_entry_t *)KPDPphys)[i + j] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_A_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
         *
         * Stuff for our DMAP.  Use 2MB pages even when 1GB pages
         * are available in order to allow APU code to adjust page
         * attributes on a fixed grain (see pmap_change_attr()).
         */
#if 0
        if ((amd_feature & AMDID_PAGE1GB) == 0)
#endif
        {
                /*
                 * Use 2MB pages
                 */
                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_A_IDX];
                }
        }
#if 0
        else {
                /*
                 * 1GB pages
                 */
                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];
                }
        }
#endif

        /* 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_A_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 << PAGE_SHIFT)) |
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_A_IDX];
        }

        /*
         * Connect the KVA slot up to the PML4
         */
        for (j = 0; j < NKPML4E; ++j) {
                ((pdp_entry_t *)KPML4phys)[KPML4I + j] =
                    KPDPphys + ((vm_paddr_t)j << PAGE_SHIFT);
                ((pdp_entry_t *)KPML4phys)[KPML4I + j] |=
                    pmap_bits_default[PG_RW_IDX] |
                    pmap_bits_default[PG_V_IDX] |
                    pmap_bits_default[PG_A_IDX];
        }
        cpu_mfence();
        cpu_invltlb();
}

/*
 *      Bootstrap the system enough to run with virtual memory.
 *
 *      On x86_64 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.
         */
        x86_64_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;

        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;
        int i;

        /*
         * 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;
        }

        for (i = 0; i < 8; ++i) {
                pt_entry_t pte;

                pte = pat_pte_index[i];
                if (pte & X86_PG_PTE_PAT) {
                        pte &= ~X86_PG_PTE_PAT;
                        pte |= X86_PG_PDE_PAT;
                }
                pat_pde_index[i] = pte;
        }
}

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

        /*
         * Check for SMAP support and enable if available.  Must be done
         * after cr3 is loaded, and on all cores.
         */
        if (cpu_stdext_feature & CPUID_STDEXT_SMAP) {
                load_cr4(rcr4() | CR4_SMAP);
        }
        if (cpu_stdext_feature & CPUID_STDEXT_SMEP) {
                load_cr4(rcr4() | CR4_SMEP);
        }
}

/*
 * Early initialization of 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)
{
        vm_pindex_t initial_pvs;
        vm_pindex_t i;

        /*
         * 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];
#ifdef PMAP_ADVANCED
                m->md.interlock_count = 0;
#else
                m->md.pmap_count = 0;
                m->md.writeable_count = 0;
#endif
        }

        /*
         * 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.
 *
 * Also create the kernel page table template for isolated user
 * pmaps.
 */
static void pmap_init_iso_range(vm_offset_t base, size_t bytes);
static void pmap_init2_iso_pmap(void);
#if 0
static void dump_pmap(pmap_t pmap, pt_entry_t pte, int level, vm_offset_t base);
#endif

void
pmap_init2(void)
{
        vm_pindex_t entry_max;

        /*
         * We can significantly reduce pv_entry_max from historical
         * levels because pv_entry's are no longer use for PTEs at the
         * leafs.  This prevents excessive pcpu caching on many-core
         * boxes (even with the further '/ 16' done in zinitna().
         *
         * Remember, however, that processes can share physical pages
         * with each process still needing the pdp/pd/pt infrstructure
         * (which still use pv_entry's).  And don't just assume that
         * every PT will be completely filled up.  So don't make it
         * too small.
         */
        entry_max = maxproc * 32 + vm_page_array_size / 16;
        TUNABLE_LONG_FETCH("vm.pmap.pv_entries", &entry_max);
        vm_pmap_pv_entries = entry_max;

        /*
         * Subtract out pages already installed in the zone (hack)
         */
        if (entry_max <= MINPV)
                entry_max = MINPV;

        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 0
        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;
        }
#endif
        /*
         * Disable so vm_map_backing iterations do not race
         */
        pmap_dynamic_delete = 0;

        /*
         * Automatic detection of Intel meltdown bug requiring user/kernel
         * mmap isolation.
         *
         * Currently there are so many Intel cpu's impacted that its better
         * to whitelist future Intel CPUs.  Most? AMD cpus are not impacted
         * so the default is off for AMD.
         */
        if (meltdown_mitigation < 0) {
                if (cpu_vendor_id == CPU_VENDOR_INTEL)
                        meltdown_mitigation = 1;
                else
                        meltdown_mitigation = 0;
        }
        if (meltdown_mitigation) {
                kprintf("machdep.meltdown_mitigation enabled to "
                        "protect against (mostly Intel) meltdown bug\n");
                kprintf("system call performance will be impacted\n");
        }

        pmap_init2_iso_pmap();
}

/*
 * Create the isolation pmap template.  Once created, the template
 * is static and its PML4e entries are used to populate the
 * kernel portion of any isolated user pmaps.
 *
 * Our isolation pmap must contain:
 * (1) trampoline area for all cpus
 * (2) common_tss area for all cpus (its part of the trampoline area now)
 * (3) IDT for all cpus
 * (4) GDT for all cpus
 */
static void
pmap_init2_iso_pmap(void)
{
        int n;

        if (bootverbose)
                kprintf("Initialize isolation pmap\n");

        /*
         * Try to use our normal API calls to make this easier.  We have
         * to scrap the shadowed kernel PDPs pmap_pinit() creates for our
         * iso_pmap.
         */
        pmap_pinit(&iso_pmap);
        bzero(iso_pmap.pm_pml4, PAGE_SIZE);

        /*
         * Install areas needed by the cpu and trampoline.
         */
        for (n = 0; n < ncpus; ++n) {
                struct privatespace *ps;

                ps = CPU_prvspace[n];
                pmap_init_iso_range((vm_offset_t)&ps->trampoline,
                                    sizeof(ps->trampoline));
                pmap_init_iso_range((vm_offset_t)&ps->dblstack,
                                    sizeof(ps->dblstack));
                pmap_init_iso_range((vm_offset_t)&ps->dbgstack,
                                    sizeof(ps->dbgstack));
                pmap_init_iso_range((vm_offset_t)&ps->common_tss,
                                    sizeof(ps->common_tss));
                pmap_init_iso_range(r_idt_arr[n].rd_base,
                                    r_idt_arr[n].rd_limit + 1);
        }
        pmap_init_iso_range((register_t)gdt, sizeof(gdt));
        pmap_init_iso_range((vm_offset_t)(int *)btext,
                            (vm_offset_t)(int *)etext -
                             (vm_offset_t)(int *)btext);

#if 0
        kprintf("Dump iso_pmap:\n");
        dump_pmap(&iso_pmap, vtophys(iso_pmap.pm_pml4), 0, 0);
        kprintf("\nDump kernel_pmap:\n");
        dump_pmap(&kernel_pmap, vtophys(kernel_pmap.pm_pml4), 0, 0);
#endif
}

/*
 * This adds a kernel virtual address range to the isolation pmap.
 */
static void
pmap_init_iso_range(vm_offset_t base, size_t bytes)
{
        pv_entry_t pv;
        pv_entry_t pvp;
        pt_entry_t *ptep;
        pt_entry_t pte;
        vm_offset_t va;

        if (bootverbose) {
                kprintf("isolate %016jx-%016jx (%zd)\n",
                        base, base + bytes, bytes);
        }
        va = base & ~(vm_offset_t)PAGE_MASK;
        while (va < base + bytes) {
                if ((va & PDRMASK) == 0 && va + NBPDR <= base + bytes &&
                    (ptep = pmap_pt(&kernel_pmap, va)) != NULL &&
                    (*ptep & kernel_pmap.pmap_bits[PG_V_IDX]) &&
                    (*ptep & kernel_pmap.pmap_bits[PG_PS_IDX])) {
                        /*
                         * Use 2MB pages if possible
                         */
                        pte = *ptep;
                        pv = pmap_allocpte(&iso_pmap, pmap_pd_pindex(va), &pvp);
                        ptep = pv_pte_lookup(pv, (va >> PDRSHIFT) & 511);
                        *ptep = pte;
                        va += NBPDR;
                } else {
                        /*
                         * Otherwise use 4KB pages
                         */
                        pv = pmap_allocpte(&iso_pmap, pmap_pt_pindex(va), &pvp);
                        ptep = pv_pte_lookup(pv, (va >> PAGE_SHIFT) & 511);
                        *ptep = vtophys(va) | kernel_pmap.pmap_bits[PG_RW_IDX] |
                                              kernel_pmap.pmap_bits[PG_V_IDX] |
                                              kernel_pmap.pmap_bits[PG_A_IDX] |
                                              kernel_pmap.pmap_bits[PG_M_IDX];

                        va += PAGE_SIZE;
                }
                pv_put(pv);
                pv_put(pvp);
        }
}

#if 0
/*
 * Useful debugging pmap dumper, do not remove (#if 0 when not in use)
 */
static
void
dump_pmap(pmap_t pmap, pt_entry_t pte, int level, vm_offset_t base)
{
        pt_entry_t *ptp;
        vm_offset_t incr;
        int i;

        switch(level) {
        case 0:                                 /* PML4e page, 512G entries */
                incr = (1LL << 48) / 512;
                break;
        case 1:                                 /* PDP page, 1G entries */
                incr = (1LL << 39) / 512;
                break;
        case 2:                                 /* PD page, 2MB entries */
                incr = (1LL << 30) / 512;
                break;
        case 3:                                 /* PT page, 4KB entries */
                incr = (1LL << 21) / 512;
                break;
        default:
                incr = 0;
                break;
        }

        if (level == 0)
                kprintf("cr3 %016jx @ va=%016jx\n", pte, base);
        ptp = (void *)PHYS_TO_DMAP(pte & ~(pt_entry_t)PAGE_MASK);
        for (i = 0; i < 512; ++i) {
                if (level == 0 && i == 128)
                        base += 0xFFFF000000000000LLU;
                if (ptp[i]) {
                        kprintf("%*.*s ", level * 4, level * 4, "");
                        if (level == 1 && (ptp[i] & 0x180) == 0x180) {
                                kprintf("va=%016jx %3d term %016jx (1GB)\n",
                                        base, i, ptp[i]);
                        } else if (level == 2 && (ptp[i] & 0x180) == 0x180) {
                                kprintf("va=%016jx %3d term %016jx (2MB)\n",
                                        base, i, ptp[i]);
                        } else if (level == 3) {
                                kprintf("va=%016jx %3d term %016jx\n",
                                        base, i, ptp[i]);
                        } else {
                                kprintf("va=%016jx %3d deep %016jx\n",
                                        base, i, ptp[i]);
                                dump_pmap(pmap, ptp[i], level + 1, base);
                        }
                }
                base += incr;
        }
}

#endif

/*
 * Typically used to initialize a fictitious page by vm/device_pager.c
 */
void
pmap_page_init(struct vm_page *m)
{
        vm_page_init(m);
#ifdef PMAP_ADVANCED
        m->md.interlock_count = 0;
#else
        m->md.pmap_count = 0;
        m->md.writeable_count = 0;
#endif
}

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

/*
 * 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 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 the 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)
                        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) {
                                /* 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_pte[(*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_pte,
              sizeof(pat_pte_index));
        bcopy(pat_pde_index, pmap->pmap_cache_bits_pde,
              sizeof(pat_pte_index));
        pmap->pmap_cache_mask_pte = X86_PG_NC_PWT | X86_PG_NC_PCD | X86_PG_PTE_PAT;
        pmap->pmap_cache_mask_pde = X86_PG_NC_PWT | X86_PG_NC_PCD | X86_PG_PDE_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;
        pmap->fuwordadd32 = std_fuwordadd32;
        pmap->fuwordadd64 = std_fuwordadd64;
}
/*
 * 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_pt = NULL;
        pmap->pm_pvhint_unused = 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_pt = NULL;
        pmap->pm_pvhint_unused = 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 * 2,
                                                        VM_SUBSYS_PML4);
                pmap->pm_pml4_iso = (void *)((char *)pmap->pm_pml4 + PAGE_SIZE);
        }

        /*
         * Allocate the PML4e table, 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 << PAGE_SHIFT)) |
                            pmap->pmap_bits[PG_RW_IDX] |
                            pmap->pmap_bits[PG_V_IDX] |
                            pmap->pmap_bits[PG_A_IDX];
                }
                for (j = 0; j < NKPML4E; ++j) {
                        pmap->pm_pml4[KPML4I + j] =
                            (KPDPphys + ((vm_paddr_t)j << PAGE_SHIFT)) |
                            pmap->pmap_bits[PG_RW_IDX] |
                            pmap->pmap_bits[PG_V_IDX] |
                            pmap->pmap_bits[PG_A_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];
        } else {
                KKASSERT(pv->pv_m->flags & PG_MAPPED);
                KKASSERT(pv->pv_m->flags & PG_WRITEABLE);
        }
        KKASSERT(pmap->pm_pml4[255] == 0);

        /*
         * When implementing an isolated userland pmap, a second PML4e table
         * is needed.  We use pmap_pml4_pindex() + 1 for convenience, but
         * note that we do not operate on this table using our API functions
         * so handling of the + 1 case is mostly just to prevent implosions.
         *
         * We install an isolated version of the kernel PDPs into this
         * second PML4e table.  The pmap code will mirror all user PDPs
         * between the primary and secondary PML4e table.
         */
        if ((pv = pmap->pm_pmlpv_iso) == NULL && meltdown_mitigation &&
            pmap != &iso_pmap) {
                pv = pmap_allocpte(pmap, pmap_pml4_pindex() + 1, NULL);
                pmap->pm_pmlpv_iso = pv;
                pmap_kenter((vm_offset_t)pmap->pm_pml4_iso,
                            VM_PAGE_TO_PHYS(pv->pv_m));
                pv_put(pv);

                /*
                 * Install an isolated version of the kernel pmap for
                 * user consumption, using PDPs constructed in iso_pmap.
                 */
                for (j = 0; j < NKPML4E; ++j) {
                        pmap->pm_pml4_iso[KPML4I + j] =
                                iso_pmap.pm_pml4[KPML4I + j];
                }
        } else if (pv) {
                KKASSERT(pv->pv_m->flags & PG_MAPPED);
                KKASSERT(pv->pv_m->flags & PG_WRITEABLE);
        }
}

/*
 * 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, 1);
                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_UNQUEUED);
                vm_page_unwire(p, 0);
                vm_page_flag_clear(p, PG_MAPPED | PG_WRITEABLE);
                vm_page_free(p);
                pmap->pm_pmlpv = NULL;
        }
        if ((pv = pmap->pm_pmlpv_iso) != NULL) {
                if (pv_hold_try(pv) == 0)
                        pv_lock(pv);
                KKASSERT(pv == pmap->pm_pmlpv_iso);
                p = pmap_remove_pv_page(pv, 1);
                pv_free(pv, NULL);
                pv = NULL;      /* safety */
                pmap_kremove((vm_offset_t)pmap->pm_pml4_iso);
                vm_page_busy_wait(p, FALSE, "pgpun");
                KKASSERT(p->flags & PG_UNQUEUED);
                vm_page_unwire(p, 0);
                vm_page_flag_clear(p, PG_MAPPED | PG_WRITEABLE);
                vm_page_free(p);
                pmap->pm_pmlpv_iso = 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 * 2);
                pmap->pm_pml4 = NULL;
                pmap->pm_pml4_iso = 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;
        pt_entry_t *ptep_iso;
        pv_entry_t pv;
        pv_entry_t pvp;
        pt_entry_t v;
        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);

        /*
         * DragonFly doesn't use PV's to represent terminal PTEs any more.
         * The index range is still used for placemarkers, but not for
         * actual pv_entry's.
         */
        KKASSERT(ptepindex >= pmap_pt_pindex(0));

        /*
         * 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!
         *
         * However, its convenient for us to allow the case when creating
         * iso_pmap.  This is a bit of a hack but it simplifies iso_pmap
         * a lot.
         */

        /*
         * 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 */
        pmap_zero_page(VM_PAGE_TO_PHYS(m));
        m->valid = VM_PAGE_BITS_ALL;
        vm_page_flag_set(m, PG_MAPPED | PG_WRITEABLE | PG_UNQUEUED);
        KKASSERT(m->queue == PQ_NONE);

        pv->pv_m = 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_RW_IDX] |
                     pmap->pmap_bits[PG_V_IDX] |
                     pmap->pmap_bits[PG_A_IDX]);
                if (ptepindex < NUPTE_USER)
                        v |= pmap->pmap_bits[PG_U_IDX];
                if (ptepindex < pmap_pt_pindex(0))
                        v |= pmap->pmap_bits[PG_M_IDX];

                ptep = pv_pte_lookup(pvp, ptepindex);
                if (pvp == pmap->pm_pmlpv && pmap->pm_pmlpv_iso)
                        ptep_iso = pv_pte_lookup(pmap->pm_pmlpv_iso, ptepindex);
                else
                        ptep_iso  = NULL;
                if (*ptep & pmap->pmap_bits[PG_V_IDX]) {
                        panic("pmap_allocpte: ptpte present without pv_entry!");
                } else {
                        pt_entry_t pte;

                        pte = atomic_swap_long(ptep, v);
                        if (ptep_iso)
                                atomic_swap_long(ptep_iso, 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_RW_IDX] |
                     pmap->pmap_bits[PG_V_IDX] |
                     pmap->pmap_bits[PG_A_IDX]);
                if (ptepindex < NUPTE_USER)
                        v |= pmap->pmap_bits[PG_U_IDX];
                if (ptepindex < pmap_pt_pindex(0))
                        v |= 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);
}

/*
 * 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.  Two if
         * the pmap has implemented an isolated userland PML4E table.
         * No wired pages should remain.
         */
        int expected_res = 0;

        if ((pmap->pm_flags & PMAP_FLAG_SIMPLE) == 0)
                ++expected_res;
        if (pmap->pm_pmlpv_iso)
                ++expected_res;

#if 1
        if (pmap->pm_stats.resident_count != expected_res ||
            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 == expected_res);
        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.  We always calculate the
                 * normal PML4 here, not the isolated PML4.
                 */
                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.
         *
         * XXX this code is operating on a user page rather than
         *     a page-table page and cannot safely clear the PG_MAPPED
         *     and PG_WRITEABLE bits.  (XXX clearing these bits should
         *     be safe in PMAP_ADVANCED mode).
         *
         * XXX It is unclear if this code ever gets called because we
         *     no longer use pv's to track terminal pages.
         */
        if (pv->pv_pindex < pmap_pt_pindex(0)) {
                pmap_remove_pv_page(pv, 0);
                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.
         *
         * This covers both the normal and the isolated PML4 page.
         */
        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, 1);
        vm_page_busy_wait(p, FALSE, "pmaprl");
        if (p->wire_count != 1) {
                const char *tstr;

                if (pv->pv_pindex >= pmap_pdp_pindex(0))
                        tstr = "PDP";
                else if (pv->pv_pindex >= pmap_pd_pindex(0))
                        tstr = "PD";
                else if (pv->pv_pindex >= pmap_pt_pindex(0))
                        tstr = "PT";
                else
                        tstr = "PTE";

                kprintf("p(%s) p->wire_count was %016lx %d\n",
                        tstr, pv->pv_pindex, p->wire_count);
        }
        KKASSERT(p->wire_count == 1);
        KKASSERT(p->flags & PG_UNQUEUED);

        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.
                 *
                 * This is either the normal or isolated PML4E table.
                 * Only the normal is used in regular operation, the isolated
                 * is only passed in when breaking down the whole pmap.
                 */
                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;
                pml4_entry_t *pdp_iso;

                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);

                /*
                 * Also remove the PDP from the isolated PML4E if the
                 * process uses one.
                 */
                if (pvp == pmap->pm_pmlpv && pmap->pm_pmlpv_iso) {
                        pdp_iso = &pmap->pm_pml4_iso[pdp_index &
                                                ((1ul << NPML4EPGSHIFT) - 1)];
                        pmap_inval_bulk(bulk, (vm_offset_t)-1, pdp_iso, 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 {
                KKASSERT(0);
        }

        /*
         * 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, 1);
                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);
        }
#if !defined(PMAP_ADVANCED)
        else if (destroy == 2) {
                /*
                 * Normal page, remove from pmap and leave the underlying
                 * page untouched.
                 *
                 * XXX REMOVE ME, destroy can no longer be 2.
                 */
                pmap_remove_pv_page(pv, 0);
                pv_free(pv, pvp);
                pv = NULL;              /* safety */
        }
#endif

        /*
         * 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 != &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, int clrpgbits)
{
        vm_page_t m;

        m = pv->pv_m;
        pv->pv_m = NULL;
        if (clrpgbits)
                vm_page_flag_clear(m, PG_MAPPED | PG_WRITEABLE);

        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 *pd, 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;

                for (;;) {
                        pt = pmap_pt(&kernel_pmap, kernel_vm_end);
                        if (pt == NULL)
                                break;
                        if ((*pt & kernel_pmap.pmap_bits[PG_V_IDX]) == 0)
                                break;
                        kernel_vm_end = (kernel_vm_end + PAGE_SIZE * NPTEPG) &
                                        ~(vm_offset_t)(PAGE_SIZE * NPTEPG - 1);
                        if (kernel_vm_end - 1 >= vm_map_max(&kernel_map)) {
                                kernel_vm_end = vm_map_max(&kernel_map);
                                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, (vm_offset_t)(PAGE_SIZE * NPTEPG));
        kend = roundup2(kend, (vm_offset_t)(PAGE_SIZE * NPTEPG));

        if (kend - 1 >= vm_map_max(&kernel_map))
                kend = vm_map_max(&kernel_map);

        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);
                        pd = pmap_pd(&kernel_pmap, kstart);

                        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]);
                        atomic_swap_long(pd, newpd);

#if 0
                        kprintf("NEWPD pd=%p pde=%016jx phys=%016jx\n",
                                pd, newpd, paddr);
#endif

                        continue; /* try again */
                }

                if ((*pt & kernel_pmap.pmap_bits[PG_V_IDX]) != 0) {
                        kstart = (kstart + PAGE_SIZE * NPTEPG) &
                                 ~(vm_offset_t)(PAGE_SIZE * NPTEPG - 1);
                        if (kstart - 1 >= vm_map_max(&kernel_map)) {
                                kstart = vm_map_max(&kernel_map);
                                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]);
                atomic_swap_long(pt, newpt);

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

                if (kstart - 1 >= vm_map_max(&kernel_map)) {
                        kstart = vm_map_max(&kernel_map);
                        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);
}

void
pmap_maybethreaded(pmap_t pmap)
{
        atomic_set_int(&pmap->pm_flags, PMAP_MULTI);
}

/*
 * Called while page is hard-busied to clear the PG_MAPPED and PG_WRITEABLE
 * flags if able.  This can happen when the pmap code is unable to clear
 * the bits in prior actions due to not holding the page hard-busied at
 * the time.
 *
 * When PMAP_ADVANCED is enabled the clearing of PG_MAPPED/WRITEABLE
 * is an optional optimization done when the pte is removed and only
 * if the pte has not been multiply-mapped.  The caller may have to
 * call vm_page_protect() if the bits are still set here.
 *
 * When PMAP_ADVANCED is disabled we check pmap_count to synchronize
 * the clearing of PG_MAPPED etc.  The caller only has to call
 * vm_page_protect() if the page is still actually mapped.
 *
 * This function is expected to be quick.
 */
int
pmap_mapped_sync(vm_page_t m)
{
#if !defined(PMAP_ADVANCED)
        if (m->flags & (PG_MAPPED | PG_WRITEABLE)) {
                if (m->md.pmap_count == 0) {
                        vm_page_flag_clear(m, PG_MAPPED | PG_MAPPEDMULTI |
                                              PG_WRITEABLE);
                }
        }
#endif
        return (m->flags);
}

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

/*
 * Hold a pv without locking it
 */
#if 0
static void
pv_hold(pv_entry_t pv)
{
        atomic_add_int(&pv->pv_hold, 1);
}
#endif

/*
 * 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).
         */
        count = pv->pv_hold;
        cpu_ccfence();
        for (;;) {
                if ((count & PV_HOLD_LOCKED) == 0) {
                        if (atomic_fcmpset_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_fcmpset_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 1
                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 = pv_entry_lookup(pmap, 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) {
                                tsleep_interlock(pmark, 0);
                                atomic_set_long(pmark, PM_PLACEMARK_WAKEUP);
                                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;
                        pnew->pv_flags = 0;
#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;

                        KASSERT(pv == NULL, ("pv insert failed %p->%p", pnew, pv));
                        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 1
                        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 = pv_entry_lookup(pmap, 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) {
                                tsleep_interlock(pmark, 0);
                                atomic_set_long(pmark, PM_PLACEMARK_WAKEUP);
                                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)) {
                        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 = pv_entry_lookup(pmap, 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)) {
                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_pt == pv)
                        pmap->pm_pvhint_pt = NULL;
                if (pmap->pm_pvhint_unused == pv)
                        pmap->pm_pvhint_unused = 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) {
                        if (vm_page_unwire_quick(pvp->pv_m))
                                panic("_pv_free: bad wirecount on pvp");
                }
                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: pv_entries exhausted -- "
                        "suggest increasing vm.pmap_pv_entries above %ld\n",
                        vm_pmap_pv_entries);
                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 *,
                     vm_pindex_t *, pv_entry_t, 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 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);
                        KKASSERT(pte_pv == NULL);
                        ptep = vtopte(info->sva);
                } else {
                        /*
                         * 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);
                        KKASSERT(pte_pv == NULL);
                        pt_pv = pv_get(pmap, pmap_pt_pindex(info->sva),
                                       &pt_placemark);
                        if (pt_pv == NULL) {
#if 0
                                KKASSERT(0);
                                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,
                                                     pt_placemark, pd_pv,
                                                     info->sva, ptep,
                                                     info->arg);
                                        } else {
                                                pv_placemarker_wakeup(pmap,
                                                                  pt_placemark);
                                        }
                                        pv_put(pd_pv);
                                } else {
                                        pv_placemarker_wakeup(pmap,
                                                              pt_placemark);
                                }
#else
                                pv_placemarker_wakeup(pmap, pt_placemark);
#endif
                                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 {
                        KASSERT((oldpte & 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, pte_placemark, pt_pv,
                                   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, PD, and PT
                 * pv_entry's.  pv_entry's are not used for PTEs.
                 */
                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 a shared page table
                 * page (NOT IMPLEMENTED XXX) 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.
                 *
                 *          XXX This should no longer be the case because
                 *          we have pt_placemark.
                 */
                if (pt_pv == NULL) {
#if 0
                        /* XXX REMOVED */
                        /*
                         * 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.
                         */
                        KKASSERT(0);
                        ptep = pv_pte_lookup(pd_pv, pmap_pt_index(sva));
                        if (*ptep & pmap->pmap_bits[PG_V_IDX]) {
                                info->func(pmap, info, pt_placemark, pd_pv,
                                           sva, ptep, info->arg);
                        } else {
                                pv_placemarker_wakeup(pmap, pt_placemark);
                        }
#else
                        pv_placemarker_wakeup(pmap, pt_placemark);
#endif

                        /*
                         * 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) {
                        vm_pindex_t *pte_placemark;
                        pv_entry_t pte_pv;

                        /*
                         * 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 pte_placemark.  pte_pv's won't exist
                         * for leaf pages.
                         *
                         * 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);
                        KKASSERT(pte_pv == NULL);
                        if (error) {
                                if (pd_pv) {
                                        pv_put(pd_pv);  /* lock order */
                                        pd_pv = NULL;
                                }
                                if (pt_pv) {
                                        pv_put(pt_pv);  /* lock order */
                                        pt_pv = NULL;
                                }
                                pv_placemarker_wait(pmap, pte_placemark);
                                va_next = sva;          /* retry */
                                break;
                        }

                        /*
                         * Reload *ptep after successfully locking the
                         * pindex.
                         */
                        cpu_ccfence();
                        oldpte = *ptep;
                        if (oldpte == 0) {
                                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 placemarker
                         * is consumed by the callback.
                         */
                        if (oldpte & pmap->pmap_bits[PG_MANAGED_IDX]) {
                                /*
                                 * Managed pte
                                 */
                                KASSERT((oldpte & pmap->pmap_bits[PG_V_IDX]),
                                    ("badC *ptep %016lx/%016lx sva %016lx",
                                    *ptep, oldpte, sva));
                                /*
                                 * 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_placemark
                                 * and may destroy but will not dispose
                                 * of pt_pv.
                                 */
                                info->func(pmap, info, pte_placemark, pt_pv,
                                           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_placemark
                                 * and may destroy but will not dispose
                                 * of pt_pv.
                                 */
                                KASSERT((oldpte & pmap->pmap_bits[PG_V_IDX]),
                                    ("badD *ptep %016lx/%016lx sva %016lx ",
                                     *ptep, oldpte, sva));
                                info->func(pmap, info, pte_placemark, pt_pv,
                                           sva, ptep, info->arg);
                        }
                        if (pd_pv) {
                                pv_lock(pd_pv);
                                if (vm_page_unwire_quick(pd_pv->pv_m)) {
                                        panic("pmap_scan_callback: "
                                              "bad wirecount on pd_pv");
                                }
                                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;
                        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,
                     vm_pindex_t *pte_placemark, pv_entry_t pt_pv,
                     vm_offset_t va, pt_entry_t *ptep, void *arg __unused)
{
        pt_entry_t pte;
#ifdef PMAP_ADVANCED
        vm_page_t oldm;
#endif

        /*
         * Managed or 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.
         */
#ifdef PMAP_ADVANCED
        pte = *ptep;
        if (pte & pmap->pmap_bits[PG_MANAGED_IDX]) {
                oldm = PHYS_TO_VM_PAGE(pte & PG_FRAME);
                atomic_add_long(&oldm->md.interlock_count, 1);
        } else {
                oldm = NULL;
        }
#endif

        pte = pmap_inval_bulk(info->bulk, va, ptep, 0);
        if (pte & pmap->pmap_bits[PG_MANAGED_IDX]) {
                vm_page_t p;

                p = PHYS_TO_VM_PAGE(pte & PG_FRAME);
                KKASSERT(pte & pmap->pmap_bits[PG_V_IDX]);
                if (pte & pmap->pmap_bits[PG_M_IDX])
                        vm_page_dirty(p);
                if (pte & pmap->pmap_bits[PG_A_IDX])
                        vm_page_flag_set(p, PG_REFERENCED);

                /*
                 * (p) is not hard-busied.
                 *
                 * If PMAP_ADVANCED mode is enabled we can safely
                 * clear PG_MAPPED and PG_WRITEABLE only if PG_MAPPEDMULTI
                 * is not set, atomically.
                 */
                pmap_removed_pte(p, pte);
        }
        if (pte & pmap->pmap_bits[PG_V_IDX]) {
                atomic_add_long(&pmap->pm_stats.resident_count, -1);
                if (pt_pv && vm_page_unwire_quick(pt_pv->pv_m))
                        panic("pmap_remove: insufficient wirecount");
        }
        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);
        pv_placemarker_wakeup(pmap, pte_placemark);
#ifdef PMAP_ADVANCED
        if (oldm) {
                if ((atomic_fetchadd_long(&oldm->md.interlock_count, -1) &
                     0x7FFFFFFFFFFFFFFFLU) == 0x4000000000000001LU) {
                        atomic_clear_long(&oldm->md.interlock_count,
                                          0x4000000000000000LU);
                        wakeup(&oldm->md.interlock_count);
                }
        }
#endif
}

/*
 * 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.
 *
 * The page must be busied by its caller, preventing new ptes from being
 * installed.  This allows us to assert that pmap_count is zero and safely
 * clear the MAPPED and WRITEABLE bits upon completion.
 */
static
void
pmap_remove_all(vm_page_t m)
{
#ifdef PMAP_ADVANCED
        long icount;
#endif
        int retry;

        if (__predict_false(!pmap_initialized))
                return;

        /*
         * pmap_count doesn't cover fictitious pages, but PG_MAPPED does
         * (albeit without certain race protections).
         */
#if 0
        if (m->md.pmap_count == 0)
                return;
#endif
        if ((m->flags & PG_MAPPED) == 0)
                return;

        retry = ticks + hz * 60;
again:
        PMAP_PAGE_BACKING_SCAN(m, NULL, ipmap, iptep, ipte, iva) {
                if (!pmap_inval_smp_cmpset(ipmap, iva, iptep, ipte, 0))
                        PMAP_PAGE_BACKING_RETRY;
                if (ipte & ipmap->pmap_bits[PG_MANAGED_IDX]) {
                        if (ipte & ipmap->pmap_bits[PG_M_IDX])
                                vm_page_dirty(m);
                        if (ipte & ipmap->pmap_bits[PG_A_IDX])
                                vm_page_flag_set(m, PG_REFERENCED);

                        /*
                         * NOTE: m is not hard-busied so it is not safe to
                         *       clear PG_MAPPED and PG_WRITEABLE on the 1->0
                         *       transition against them being set in
                         *       pmap_enter().
                         */
                        pmap_removed_pte(m, ipte);
                }

                /*
                 * Cleanup various tracking counters.  pt_pv can't go away
                 * due to our wired ref.
                 */
                if (ipmap != &kernel_pmap) {
                        pv_entry_t pt_pv;

                        spin_lock_shared(&ipmap->pm_spin);
                        pt_pv = pv_entry_lookup(ipmap, pmap_pt_pindex(iva));
                        spin_unlock_shared(&ipmap->pm_spin);

                        if (pt_pv) {
                                if (vm_page_unwire_quick(pt_pv->pv_m)) {
                                        panic("pmap_remove_all: bad "
                                              "wire_count on pt_pv");
                                }
                                atomic_add_long(
                                        &ipmap->pm_stats.resident_count, -1);
                        }
                }
                if (ipte & ipmap->pmap_bits[PG_W_IDX])
                        atomic_add_long(&ipmap->pm_stats.wired_count, -1);
                if (ipte & ipmap->pmap_bits[PG_G_IDX])
                        cpu_invlpg((void *)iva);
        } PMAP_PAGE_BACKING_DONE;

#ifdef PMAP_ADVANCED
        /*
         * If our scan lost a pte swap race oldm->md.interlock_count might
         * be set from the pmap_enter() code.  If so sleep a little and try
         * again.
         */
        icount = atomic_fetchadd_long(&m->md.interlock_count,
                                      0x8000000000000000LU) +
                 0x8000000000000000LU;
        cpu_ccfence();
        while (icount & 0x3FFFFFFFFFFFFFFFLU) {
                tsleep_interlock(&m->md.interlock_count, 0);
                if (atomic_fcmpset_long(&m->md.interlock_count, &icount,
                                        icount | 0x4000000000000000LU)) {
                        tsleep(&m->md.interlock_count, PINTERLOCKED,
                               "pgunm", 1);
                        icount = m->md.interlock_count;
                        if (retry - ticks > 0)
                                goto again;
                        panic("pmap_remove_all: cannot return interlock_count "
                              "to 0 (%p, %ld)",
                              m, m->md.interlock_count);
                }
        }
#else
        /*
         * pmap_count should be zero but it is possible to race a pmap_enter()
         * replacement (see 'oldm').  Once it is zero it cannot become
         * non-zero because the page is hard-busied.
         */
        if (m->md.pmap_count || m->md.writeable_count) {
                tsleep(&m->md.pmap_count, 0, "pgunm", 1);
                if (retry - ticks > 0)
                        goto again;
                panic("pmap_remove_all: cannot return pmap_count "
                      "to 0 (%p, %ld, %ld)",
                      m, m->md.pmap_count, m->md.writeable_count);
        }
#endif
        vm_page_flag_clear(m, PG_MAPPED | PG_MAPPEDMULTI | PG_WRITEABLE);
}

/*
 * Removes the page from a particular pmap.
 *
 * The page must be busied by the caller.
 */
void
pmap_remove_specific(pmap_t pmap_match, vm_page_t m)
{
        if (__predict_false(!pmap_initialized))
                return;

        /*
         * PG_MAPPED test works for both non-fictitious and fictitious pages.
         */
        if ((m->flags & PG_MAPPED) == 0)
                return;

        PMAP_PAGE_BACKING_SCAN(m, pmap_match, ipmap, iptep, ipte, iva) {
                if (!pmap_inval_smp_cmpset(ipmap, iva, iptep, ipte, 0))
                        PMAP_PAGE_BACKING_RETRY;
                if (ipte & ipmap->pmap_bits[PG_MANAGED_IDX]) {
                        if (ipte & ipmap->pmap_bits[PG_M_IDX])
                                vm_page_dirty(m);
                        if (ipte & ipmap->pmap_bits[PG_A_IDX])
                                vm_page_flag_set(m, PG_REFERENCED);

                        /*
                         * NOTE: m is not hard-busied so it is not safe to
                         *       clear PG_MAPPED and PG_WRITEABLE on the 1->0
                         *       transition against them being set in
                         *       pmap_enter().
                         */
                        pmap_removed_pte(m, ipte);
                }

                /*
                 * Cleanup various tracking counters.  pt_pv can't go away
                 * due to our wired ref.
                 */
                if (ipmap != &kernel_pmap) {
                        pv_entry_t pt_pv;

                        spin_lock_shared(&ipmap->pm_spin);
                        pt_pv = pv_entry_lookup(ipmap, pmap_pt_pindex(iva));
                        spin_unlock_shared(&ipmap->pm_spin);

                        if (pt_pv) {
                                atomic_add_long(
                                        &ipmap->pm_stats.resident_count, -1);
                                if (vm_page_unwire_quick(pt_pv->pv_m)) {
                                        panic("pmap_remove_specific: bad "
                                              "wire_count on pt_pv");
                                }
                        }
                }
                if (ipte & ipmap->pmap_bits[PG_W_IDX])
                        atomic_add_long(&ipmap->pm_stats.wired_count, -1);
                if (ipte & ipmap->pmap_bits[PG_G_IDX])
                        cpu_invlpg((void *)iva);
        } PMAP_PAGE_BACKING_DONE;
}

/*
 * 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,
                      vm_pindex_t *pte_placemark,
                      pv_entry_t pt_pv, vm_offset_t va,
                      pt_entry_t *ptep, void *arg __unused)
{
        pt_entry_t pbits;
        pt_entry_t cbits;
        vm_page_t m;

again:
        pbits = *ptep;
        cpu_ccfence();
        cbits = pbits;
        if (pbits & pmap->pmap_bits[PG_MANAGED_IDX]) {
                cbits &= ~pmap->pmap_bits[PG_A_IDX];
                cbits &= ~pmap->pmap_bits[PG_M_IDX];
        }
        /* 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 "
                                "pt_pv=%p cbits=%08lx\n",
                                va, ptep, pt_pv, cbits
                        );
                }
#endif
                if (pbits != cbits) {
                        if (!pmap_inval_smp_cmpset(pmap, va,
                                                   ptep, pbits, cbits)) {
                                goto again;
                        }
                }
                if (pbits & pmap->pmap_bits[PG_MANAGED_IDX]) {
                        m = PHYS_TO_VM_PAGE(pbits & PG_FRAME);
                        if (pbits & pmap->pmap_bits[PG_A_IDX])
                                vm_page_flag_set(m, PG_REFERENCED);
                        if (pbits & pmap->pmap_bits[PG_M_IDX])
                                vm_page_dirty(m);
#if !defined(PMAP_ADVANCED)
                        if (pbits & pmap->pmap_bits[PG_RW_IDX])
                                atomic_add_long(&m->md.writeable_count, -1);
#endif

                }
        }
        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.
 */
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;
        pt_entry_t origpte;
        vm_paddr_t opa;
        vm_page_t oldm;
        pt_entry_t newpte;
        vm_paddr_t pa;
#if defined(PMAP_ADVANCED)
        int flags;
        int nflags;
#endif

        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 the locked page table page (pt_pv) for our new page table
         * entry, allocating it if necessary.
         *
         * There is no pte_pv for a terminal pte so the terminal pte will
         * be locked via pte_placemark.
         *
         * Only MMU actions by the CPU itself can modify the ptep out from
         * under us.
         *
         * If the pmap is still being initialized we assume existing
         * page tables.
         *
         * NOTE: Kernel mapppings do not track page table pages
         *       (i.e. there is no pt_pv pt_pv structure).
         *
         * NOTE: origpte here is 'tentative', used only to check for
         *       the degenerate case where the entry already exists and
         *       matches.
         */
        if (__predict_false(pmap_initialized == FALSE)) {
                pte_pv = NULL;
                pt_pv = NULL;
                pte_placemark = NULL;
                ptep = vtopte(va);
                origpte = *ptep;
        } else {
                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(pmap, pmap_pt_pindex(va), NULL);
                        ptep = pv_pte_lookup(pt_pv, pmap_pte_index(va));
                }
                origpte = *ptep;
                cpu_ccfence();
        }

        pa = VM_PAGE_TO_PHYS(m);

        /*
         * Calculate the new PTE.
         */
        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 ((m->flags & PG_FICTITIOUS) == 0)
                newpte |= pmap->pmap_bits[PG_MANAGED_IDX];
//      if (pmap == &kernel_pmap)
//              newpte |= pgeflag;
        newpte |= pmap->pmap_cache_bits_pte[m->pat_mode];

        /*
         * 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;
        }

        /*
         * Adjust page flags.  The page is soft-busied or hard-busied, we
         * should be able to safely set PG_* flag bits even with the (shared)
         * soft-busy.
         *
         * The pmap_count and writeable_count is only tracked for
         * non-fictitious pages.  As a bit of a safety, bump pmap_count
         * and set the PG_* bits before mapping the page.  If another part
         * of the system does not properly hard-busy the page (against our
         * soft-busy or hard-busy) in order to remove mappings it might not
         * see the pte that we are about to add and thus will not be able to
         * drop pmap_count to 0.
         *
         * The PG_MAPPED and PG_WRITEABLE flags are set for any type of page.
         *
         * NOTE! PG_MAPPED and PG_WRITEABLE can only be cleared when
         *       the page is hard-busied AND pmap_count is 0.  This
         *       interlocks our setting of the flags here.
         */
        /*vm_page_spin_lock(m);*/
#if !defined(PMAP_ADVANCED)
        if ((m->flags & PG_FICTITIOUS) == 0) {
                pmap_page_stats_adding(
                        atomic_fetchadd_long(&m->md.pmap_count, 1));
                if (newpte & pmap->pmap_bits[PG_RW_IDX])
                        atomic_add_long(&m->md.writeable_count, 1);
        }
#endif

        /*
         * In advanced mode we keep track of single mappings verses
         * multiple mappings in order to avoid unnecessary vm_page_protect()
         * calls (particularly on the kernel_map).
         *
         * If non-advanced mode we track the mapping count for similar effect.
         *
         * Avoid modifying the vm_page as much as possible, conditionalize
         * updates to reduce cache line ping-ponging.
         */
#if defined(PMAP_ADVANCED)
        flags = m->flags;
        cpu_ccfence();
        for (;;) {
                nflags = PG_MAPPED;
                if (newpte & pmap->pmap_bits[PG_RW_IDX])
                        nflags |= PG_WRITEABLE;
                if (flags & PG_MAPPED)
                        nflags |= PG_MAPPEDMULTI;
                if (flags == (flags | nflags))
                        break;
                if (atomic_fcmpset_int(&m->flags, &flags, flags | nflags))
                        break;
        }
#else
        if (newpte & pmap->pmap_bits[PG_RW_IDX]) {
                if ((m->flags & (PG_MAPPED | PG_WRITEABLE)) == 0)
                        vm_page_flag_set(m, PG_MAPPED | PG_WRITEABLE);
        } else {
                if ((m->flags & PG_MAPPED) == 0)
                        vm_page_flag_set(m, PG_MAPPED);
        }
#endif
        /*vm_page_spin_unlock(m);*/

        /*
         * A race can develop when replacing an existing mapping.  The new
         * page has been busied and the pte is placemark-locked, but the
         * old page could be ripped out from under us at any time by
         * a backing scan.
         *
         * When PMAP_ADVANCED is disabled the race is handled by having the
         * backing scans check pmap_count and writeable_count when doing
         * operations that should ensure one becomes 0.
         *
         * When PMAP_ADVANCED is enabled, if we do nothing, a concurrent
         * backing scan may clear PG_WRITEABLE and PG_MAPPED before we can
         * act on oldm.
         */
        opa = origpte & PG_FRAME;
        if (opa && (origpte & pmap->pmap_bits[PG_MANAGED_IDX])) {
                oldm = PHYS_TO_VM_PAGE(opa);
                KKASSERT(opa == oldm->phys_addr);
                KKASSERT(entry != NULL);
#ifdef PMAP_ADVANCED
                atomic_add_long(&oldm->md.interlock_count, 1);
#endif
        } else {
                oldm = NULL;
        }

        /*
         * Swap the new and old PTEs and perform any necessary SMP
         * synchronization.
         */
        if ((prot & VM_PROT_NOSYNC) || (opa == 0 && pt_pv != NULL)) {
                /*
                 * Explicitly permitted to avoid pmap cpu mask synchronization
                 * or the prior content of a non-kernel-related pmap was
                 * invalid.
                 */
                origpte = atomic_swap_long(ptep, newpte);
                if (opa)
                        cpu_invlpg((void *)va);
        } else {
                /*
                 * Not permitted to avoid pmap cpu mask synchronization
                 * or there prior content being replaced or this is a kernel
                 * related pmap.
                 *
                 * Due to other kernel optimizations, we cannot assume a
                 * 0->non_zero transition of *ptep can be done with a swap.
                 */
                origpte = pmap_inval_smp(pmap, va, 1, ptep, newpte);
        }
        opa = origpte & PG_FRAME;

#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

        /*
         * Account for the changes in the pt_pv and pmap.
         *
         * Retain the same wiring count due to replacing an existing page,
         * or bump the wiring count for a new page.
         */
        if (pt_pv && opa == 0) {
                vm_page_wire_quick(pt_pv->pv_m);
                atomic_add_long(&pt_pv->pv_pmap->pm_stats.resident_count, 1);
        }
        if (wired && (origpte & pmap->pmap_bits[PG_W_IDX]) == 0)
                atomic_add_long(&pmap->pm_stats.wired_count, 1);

        /*
         * Account for the removal of the old page.  pmap and pt_pv stats
         * have already been fully adjusted for both.
         *
         * WARNING! oldm is not soft or hard-busied.  The pte at worst can
         *          only be removed out from under us since we hold the
         *          placemarker.  So if it is still there, it must not have
         *          changed.
         *
         * WARNING! When PMAP_ADVANCED is enabled, a backing scan
         *          can clear PG_WRITEABLE and/or PG_MAPPED and rip oldm
         *          away from us, possibly even freeing or paging it, and
         *          not setting our dirtying below.
         *
         *          To deal with this, oldm->md.interlock_count is bumped
         *          to indicate that we might (only might) have won the pte
         *          swap race, and then released below.
         */
        if (opa && (origpte & pmap->pmap_bits[PG_MANAGED_IDX])) {
                KKASSERT(oldm == PHYS_TO_VM_PAGE(opa));
                if (origpte & pmap->pmap_bits[PG_M_IDX])
                        vm_page_dirty(oldm);
                if (origpte & pmap->pmap_bits[PG_A_IDX])
                        vm_page_flag_set(oldm, PG_REFERENCED);

                /*
                 * NOTE: oldm is not hard-busied so it is not safe to
                 *       clear PG_MAPPED and PG_WRITEABLE on the 1->0
                 *       transition against them being set in
                 *       pmap_enter().
                 */
                pmap_removed_pte(oldm, origpte);
        }
#ifdef PMAP_ADVANCED
        if (oldm) {
                if ((atomic_fetchadd_long(&oldm->md.interlock_count, -1) &
                     0x7FFFFFFFFFFFFFFFLU) == 0x4000000000000001LU) {
                        atomic_clear_long(&oldm->md.interlock_count,
                                          0x4000000000000000LU);
                        wakeup(&oldm->md.interlock_count);
                }
        }
#endif

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_placemark)
                pv_placemarker_wakeup(pmap, pte_placemark);
        if (pt_pv)
                pv_put(pt_pv);
}

/*
 * 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);
}

#if 0
#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);
#endif

void
pmap_object_init_pt(pmap_t pmap, vm_map_entry_t entry,
                    vm_offset_t addr, vm_size_t size, int limit)
{
#if 0
        vm_prot_t prot = entry->protection;
        vm_object_t object = entry->ba.object;
        vm_pindex_t pindex = atop(entry->ba.offset + (addr - entry->ba.start));
        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;
        info.object = object;
        info.entry = entry;

        /*
         * By using the NOLK scan, the callback function must be sure
         * to return -1 if the VM page falls out of the object.
         */
        vm_object_hold_shared(object);
        vm_page_rb_tree_RB_SCAN_NOLK(&object->rb_memq, rb_vm_page_scancmp,
                                     pmap_object_init_pt_callback, &info);
        vm_object_drop(object);
#endif
}

#if 0

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;
        int hard_busy;

        /*
         * 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;
        hard_busy = 0;
again:
        if (hard_busy) {
                if (vm_page_busy_try(p, TRUE))
                        return 0;
        } else {
                if (vm_page_sbusy_try(p))
                        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) {
                        if (hard_busy == 0) {
                                vm_page_sbusy_drop(p);
                                hard_busy = 1;
                                goto again;
                        }
                        vm_page_deactivate(p);
                }
                rel_index = p->pindex - info->start_pindex;
                pmap_enter(info->pmap, info->addr + x86_64_ptob(rel_index), p,
                           VM_PROT_READ, FALSE, info->entry);
        }
        if (hard_busy)
                vm_page_wakeup(p);
        else
                vm_page_sbusy_drop(p);

        /*
         * We are using an unlocked scan (that is, the scan expects its
         * current element to remain in the tree on return).  So we have
         * to check here and abort the scan if it isn't.
         */
        if (p->object != info->object)
                return -1;
        lwkt_yield();
        return(0);
}

#endif

/*
 * 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.
 *
 * The address must reside within a vm_map mapped range to ensure that the
 * page table doesn't get ripped out from under us.
 *
 * 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);
}

/*
 * 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.
 *
 * Currently only used to test the 'M'odified bit.  If the page
 * is not PG_WRITEABLE, the 'M'odified bit cannot be set and we
 * return immediately.  Fictitious pages do not track this bit.
 */
static
boolean_t
pmap_testbit(vm_page_t m, int bit)
{
        int res = FALSE;

        if (__predict_false(!pmap_initialized || (m->flags & PG_FICTITIOUS)))
                return FALSE;
        /*
         * Nothing to do if all the mappings are already read-only.
         * The page's [M]odify bits have already been synchronized
         * to the vm_page_t and cleaned out.
         */
#ifdef PMAP_ADVANCED
        if (bit == PG_M_IDX && (m->flags & PG_WRITEABLE) == 0)
                return FALSE;
#else
        if (bit == PG_M_IDX && m->md.writeable_count == 0)
                return FALSE;
#endif

        /*
         * Iterate the mapping
         */
        PMAP_PAGE_BACKING_SCAN(m, NULL, ipmap, iptep, ipte, iva) {
                if (ipte & ipmap->pmap_bits[bit]) {
                        res = TRUE;
                        break;
                }
        } PMAP_PAGE_BACKING_DONE;
        return res;
}

/*
 * This routine is used to modify bits in ptes.  Only one bit should be
 * specified.  PG_RW requires special handling.  This call works with
 * any sort of mapped page.  PG_FICTITIOUS pages might not be optimal.
 *
 * Caller must NOT hold any spin locks
 * Caller must hold (m) hard-busied
 *
 * 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.
 */
static __inline
void
pmap_clearbit(vm_page_t m, int bit_index)
{
        pt_entry_t npte;
        int retry;
#ifdef PMAP_ADVANCED
        long icount;
#endif

        /*
         * Too early in the boot
         */
        if (__predict_false(!pmap_initialized)) {
                if (bit_index == PG_RW_IDX)
                        vm_page_flag_clear(m, PG_WRITEABLE);
                return;
        }
#ifdef PMAP_ADVANCED
        if ((m->flags & (PG_MAPPED | PG_WRITEABLE)) == 0)
                return;
#endif

        /*
         * Being asked to clear other random bits, we don't track them
         * so we have to iterate.
         *
         * When PMAP_ADVANCED is enabled, pmap_clear_reference()
         * is called (into here) with the page hard-busied to check whether
         * the page is still mapped and will clear PG_MAPPED and PG_WRITEABLE
         * if it isn't.
         */
        if (bit_index != PG_RW_IDX) {
#if 0
#ifdef PMAP_ADVANCED
                long icount;

                icount = 0;
#endif
#endif
                PMAP_PAGE_BACKING_SCAN(m, NULL, ipmap, iptep, ipte, iva) {
#if 0
#ifdef PMAP_ADVANCED
                        ++icount;
#endif
#endif
                        if (ipte & ipmap->pmap_bits[bit_index]) {
                                atomic_clear_long(iptep,
                                                  ipmap->pmap_bits[bit_index]);
                        }
                } PMAP_PAGE_BACKING_DONE;
#if 0
#ifdef PMAP_ADVANCED
                if (icount == 0) {
                        icount = atomic_fetchadd_long(&m->md.interlock_count,
                                                      0x8000000000000000LU);
                        if ((icount & 0x3FFFFFFFFFFFFFFFLU) == 0) {
                                vm_page_flag_clear(m, PG_MAPPED |
                                                      PG_MAPPEDMULTI |
                                                      PG_WRITEABLE);
                        }
                }
#endif
#endif
                return;
        }

        /*
         * Being asked to clear the RW bit.
         *
         * Nothing to do if all the mappings are already read-only
         */
#ifdef PMAP_ADVANCED
        if ((m->flags & PG_WRITEABLE) == 0)
                return;
#else
        if (m->md.writeable_count == 0)
                return;
#endif

        /*
         * Iterate the mappings and check.
         */
        retry = ticks + hz * 60;
again:
        /*
         * Clear PG_RW. This also clears PG_M and marks the page dirty if
         * PG_M was set.
         *
         * Since the caller holds the page hard-busied we can safely clear
         * PG_WRITEABLE, and callers expect us to for the PG_RW_IDX path.
         */
        PMAP_PAGE_BACKING_SCAN(m, NULL, ipmap, iptep, ipte, iva) {
#if 0
                if ((ipte & ipmap->pmap_bits[PG_MANAGED_IDX]) == 0)
                        continue;
#endif
                if ((ipte & ipmap->pmap_bits[PG_RW_IDX]) == 0)
                        continue;
                npte = ipte & ~(ipmap->pmap_bits[PG_RW_IDX] |
                                ipmap->pmap_bits[PG_M_IDX]);
                if (!pmap_inval_smp_cmpset(ipmap, iva, iptep, ipte, npte))
                        PMAP_PAGE_BACKING_RETRY;
                if (ipte & ipmap->pmap_bits[PG_M_IDX])
                        vm_page_dirty(m);

                /*
                 * NOTE: m is not hard-busied so it is not safe to
                 *       clear PG_WRITEABLE on the 1->0 transition
                 *       against it being set in pmap_enter().
                 *
                 *       pmap_count and writeable_count are only applicable
                 *       to non-fictitious pages (PG_MANAGED_IDX from pte)
                 */
#if !defined(PMAP_ADVANCED)
                if (ipte & ipmap->pmap_bits[PG_MANAGED_IDX])
                        atomic_add_long(&m->md.writeable_count, -1);
#endif
        } PMAP_PAGE_BACKING_DONE;

#ifdef PMAP_ADVANCED
        /*
         * If our scan lost a pte swap race oldm->md.interlock_count might
         * be set from the pmap_enter() code.  If so sleep a little and try
         * again.
         *
         * Use an atomic op to access interlock_count to ensure ordering.
         */
        icount = atomic_fetchadd_long(&m->md.interlock_count,
                                      0x8000000000000000LU) +
                 0x8000000000000000LU;
        cpu_ccfence();
        while (icount & 0x3FFFFFFFFFFFFFFFLU) {
                tsleep_interlock(&m->md.interlock_count, 0);
                if (atomic_fcmpset_long(&m->md.interlock_count, &icount,
                                        icount | 0x4000000000000000LU)) {
                        tsleep(&m->md.interlock_count, PINTERLOCKED,
                               "pgunm", 1);
                        icount = m->md.interlock_count;
                        if (retry - ticks > 0)
                                goto again;
                        panic("pmap_clearbit: cannot return interlock_count "
                              "to 0 (%p, %ld)",
                              m, m->md.interlock_count);
                }
        }
#else
        /*
         * writeable_count should be zero but it is possible to race
         * a pmap_enter() replacement (see 'oldm').  Once it is zero
         * it cannot become non-zero because the page is hard-busied.
         */
        if (m->md.writeable_count != 0) {
                tsleep(&m->md.writeable_count, 0, "pgwab", 1);
                if (retry - ticks > 0)
                        goto again;
                panic("pmap_clearbit: cannot return writeable_count "
                      "to 0 (%ld)",
                      m->md.writeable_count);
        }
#endif
        vm_page_flag_clear(m, PG_WRITEABLE);
}

/*
 * Lower the permission for all mappings to a given page.
 *
 * Page must be hard-busied by caller.  Because the page is busied by the
 * 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)
{
        int rval = 0;
        pt_entry_t npte;

        if (__predict_false(!pmap_initialized || (m->flags & PG_FICTITIOUS)))
                return rval;
        PMAP_PAGE_BACKING_SCAN(m, NULL, ipmap, iptep, ipte, iva) {
                if (ipte & ipmap->pmap_bits[PG_A_IDX]) {
                        npte = ipte & ~ipmap->pmap_bits[PG_A_IDX];
                        if (!atomic_cmpset_long(iptep, ipte, npte))
                                PMAP_PAGE_BACKING_RETRY;
                        ++rval;
                        if (rval > 4)
                                break;
                }
        } PMAP_PAGE_BACKING_DONE;
        return rval;
}

/*
 *      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 bit on the vm_page.
 *
 * The page must be hard-busied.
 */
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
x86_64_protection_init(void)
{
        uint64_t *kp;
        int prot;

        /*
         * NX supported? (boot time loader.conf override only)
         *
         * -1   Automatic (sets mode 1)
         *  0   Disabled
         *  1   NX implemented, differentiates PROT_READ vs PROT_READ|PROT_EXEC
         *  2   NX implemented for all cases
         */
        TUNABLE_INT_FETCH("machdep.pmap_nx_enable", &pmap_nx_enable);
        if ((amd_feature & AMDID_NX) == 0) {
                pmap_bits_default[PG_NX_IDX] = 0;
                pmap_nx_enable = 0;
        } else if (pmap_nx_enable < 0) {
                pmap_nx_enable = 1;             /* default to mode 1 (READ) */
        }

        /*
         * 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    (pmap_nx_enable mode >= 1)
                         */
                        if (pmap_nx_enable >= 1)
                                *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
                         *                      (pmap_nx_enable mode >= 2)
                         */
                        *kp = pmap_bits_default[PG_RW_IDX];
                        if (pmap_nx_enable >= 2)
                                *kp |= 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;
                }
                ++kp;
        }
}

/*
 * 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_pte[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.
 *
 * If the va is within the DMAP we cannot use vtopte() because the DMAP
 * utilizes 2MB or 1GB pages.  2MB is forced atm so calculate the pd_entry
 * pointer based on that.
 */
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);

        if (va >= DMAP_MIN_ADDRESS && va < DMAP_MAX_ADDRESS) {
                pd_entry_t *pd;

                KKASSERT(va < DMapMaxAddress);
                pd = (pd_entry_t *)PHYS_TO_DMAP(DMPDphys);
                pd += (va - DMAP_MIN_ADDRESS) >> PDRSHIFT;

                while ((long)count > 0) {
                        *pd =
                           (*pd & ~(pd_entry_t)(kernel_pmap.pmap_cache_mask_pde)) |
                           kernel_pmap.pmap_cache_bits_pde[mode];
                        count -= NBPDR / PAGE_SIZE;
                        va += NBPDR;
                        ++pd;
                }
        } else {
                while (count) {
                        pte = vtopte(va);
                        *pte =
                           (*pte & ~(pt_entry_t)(kernel_pmap.pmap_cache_mask_pte)) |
                           kernel_pmap.pmap_cache_bits_pte[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;
                pa = pte & PG_FRAME;
                if (pte & pmap->pmap_bits[PG_MANAGED_IDX])
                        m = PHYS_TO_VM_PAGE(pa);
                else
                        m = NULL;

                /*
                 * 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, or someone else.
                 */
                if (pte & pmap->pmap_bits[PG_A_IDX]) {
                        val |= MINCORE_REFERENCED|MINCORE_REFERENCED_OTHER;
                } else if (m && ((m->flags & PG_REFERENCED) ||
                                 pmap_ts_referenced(m))) {
                        val |= MINCORE_REFERENCED_OTHER;
                        vm_page_flag_set(m, PG_REFERENCED);
                }
        } 
        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;
        thread_t td;

        oldvm = lp->lwp_vmspace;

        if (oldvm != newvm) {
                crit_enter();
                td = curthread;
                KKASSERT((newvm->vm_refcnt & VM_REF_DELETED) == 0);
                lp->lwp_vmspace = newvm;
                if (td->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) {
                                td->td_pcb->pcb_cr3 = vtophys(pmap->pm_pml4);
                                if (meltdown_mitigation && pmap->pm_pmlpv_iso) {
                                        td->td_pcb->pcb_cr3_iso =
                                                vtophys(pmap->pm_pml4_iso);
                                        td->td_pcb->pcb_flags |= PCB_ISOMMU;
                                } else {
                                        td->td_pcb->pcb_cr3_iso = 0;
                                        td->td_pcb->pcb_flags &= ~PCB_ISOMMU;
                                }
                        } else if (pmap->pmap_bits[TYPE_IDX] == EPT_PMAP) {
                                td->td_pcb->pcb_cr3 = KPML4phys;
                                td->td_pcb->pcb_cr3_iso = 0;
                                td->td_pcb->pcb_flags &= ~PCB_ISOMMU;
                        } else {
                                panic("pmap_setlwpvm: unknown pmap type\n");
                        }

                        /*
                         * The MMU separation fields needs to be updated.
                         * (it can't access the pcb directly from the
                         * restricted user pmap).
                         */
                        {
                                struct trampframe *tramp;

                                tramp = &pscpu->trampoline;
                                tramp->tr_pcb_cr3 = td->td_pcb->pcb_cr3;
                                tramp->tr_pcb_cr3_iso = td->td_pcb->pcb_cr3_iso;
                                tramp->tr_pcb_flags = td->td_pcb->pcb_flags;
                                tramp->tr_pcb_rsp = (register_t)td->td_pcb;
                                /* tr_pcb_rsp doesn't change */
                        }

                        /*
                         * In kernel-land we always use the normal PML4E
                         * so the kernel is fully mapped and can also access
                         * user memory.
                         */
                        load_cr3(td->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);

        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)
{
}

/*
 * 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_pgscan_callback - Used by pmap_pgscan to acquire the related
 * VM page and issue a pginfo->callback.
 */
static
void
pmap_pgscan_callback(pmap_t pmap, struct pmap_scan_info *info,
                      vm_pindex_t *pte_placemark,
                      pv_entry_t pt_pv, vm_offset_t va,
                      pt_entry_t *ptep, void *arg)
{
        struct pmap_pgscan_info *pginfo = arg;
        vm_page_t m;
        pt_entry_t pte;

        pte = *ptep;
        cpu_ccfence();

        if (pte & pmap->pmap_bits[PG_MANAGED_IDX]) {
                /*
                 * Try to busy the page while we hold the pte_placemark locked.
                 */
                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 pt_pv
                                 * unlocked.
                                 */
                                pv_placemarker_wakeup(pmap, pte_placemark);
                                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);
                                        if (vm_page_unwire_quick(pt_pv->pv_m)) {
                                                panic("pmap_pgscan: bad wire_"
                                                      "count on pt_pv");
                                        }
                                }
                        } else {
                                vm_page_wakeup(m);
                                pv_placemarker_wakeup(pmap, pte_placemark);
                        }
                } else {
                        ++pginfo->busycount;
                        pv_placemarker_wakeup(pmap, pte_placemark);
                }
        } 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.
 *
 * NOTE: This routine is called without the pmap spin-lock and so can
 *       race changes to *pmark.  Due to the sensitivity of the routine
 *       to possible MULTIPLE interactions from other cpus, and the
 *       overloading of the WAKEUP bit on PM_NOPLACEMARK, we have to
 *       use a cmpset loop to avoid a race that might cause the WAKEUP
 *       bit to be lost.
 *
 * Caller is expected to retry its operation upon return.
 */
static
void
pv_placemarker_wait(pmap_t pmap, vm_pindex_t *pmark)
{
        vm_pindex_t mark;

        mark = *pmark;
        cpu_ccfence();
        while (mark != PM_NOPLACEMARK) {
                tsleep_interlock(pmark, 0);
                if (atomic_fcmpset_long(pmark, &mark,
                                       mark | PM_PLACEMARK_WAKEUP)) {
                        tsleep(pmark, PINTERLOCKED, "pvplw", 0);
                        break;
                }
        }
}

/*
 * 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);
}