o Relax locking assertions for vm_page_find_least()

[FreeBSD/FreeBSD.git] / sys / arm / arm / pmap-v6.c

/* From: $NetBSD: pmap.c,v 1.148 2004/04/03 04:35:48 bsh Exp $ */
/*-
 * Copyright 2011 Semihalf
 * Copyright 2004 Olivier Houchard.
 * Copyright 2003 Wasabi Systems, Inc.
 * All rights reserved.
 *
 * Written by Steve C. Woodford for Wasabi Systems, 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 for the NetBSD Project by
 *      Wasabi Systems, Inc.
 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
 *    or promote products derived from this software without specific prior
 *    written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``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 WASABI SYSTEMS, INC
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * From: FreeBSD: src/sys/arm/arm/pmap.c,v 1.113 2009/07/24 13:50:29
 */

/*-
 * Copyright (c) 2002-2003 Wasabi Systems, Inc.
 * Copyright (c) 2001 Richard Earnshaw
 * Copyright (c) 2001-2002 Christopher Gilbert
 * All rights reserved.
 *
 * 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. The name of the company nor the name of the author may be used to
 *    endorse or promote products derived from this software without specific
 *    prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*-
 * Copyright (c) 1999 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Charles M. Hannum.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

/*-
 * Copyright (c) 1994-1998 Mark Brinicombe.
 * Copyright (c) 1994 Brini.
 * All rights reserved.
 *
 * This code is derived from software written for Brini by Mark Brinicombe
 *
 * 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 Mark Brinicombe.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR 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
 *
 * RiscBSD kernel project
 *
 * pmap.c
 *
 * Machine dependant vm stuff
 *
 * Created      : 20/09/94
 */

/*
 * Special compilation symbols
 * PMAP_DEBUG           - Build in pmap_debug_level code
 */
/* Include header files */

#include "opt_vm.h"
#include "opt_pmap.h"

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/lock.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/msgbuf.h>
#include <sys/mutex.h>
#include <sys/vmmeter.h>
#include <sys/mman.h>
#include <sys/rwlock.h>
#include <sys/smp.h>
#include <sys/sched.h>
#include <sys/sysctl.h>

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

#include <machine/md_var.h>
#include <machine/cpu.h>
#include <machine/cpufunc.h>
#include <machine/pcb.h>

#ifdef DEBUG
extern int last_fault_code;
#endif

#ifdef PMAP_DEBUG
#define PDEBUG(_lev_,_stat_) \
        if (pmap_debug_level >= (_lev_)) \
                ((_stat_))
#define dprintf printf

int pmap_debug_level = 0;
#define PMAP_INLINE
#else   /* PMAP_DEBUG */
#define PDEBUG(_lev_,_stat_) /* Nothing */
#define dprintf(x, arg...)
#define PMAP_INLINE __inline
#endif  /* PMAP_DEBUG */

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

#ifdef ARM_L2_PIPT
#define pmap_l2cache_wbinv_range(va, pa, size) cpu_l2cache_wbinv_range((pa), (size))
#define pmap_l2cache_inv_range(va, pa, size) cpu_l2cache_inv_range((pa), (size))
#else
#define pmap_l2cache_wbinv_range(va, pa, size) cpu_l2cache_wbinv_range((va), (size))
#define pmap_l2cache_inv_range(va, pa, size) cpu_l2cache_inv_range((va), (size))
#endif

extern struct pv_addr systempage;

/*
 * Internal function prototypes
 */

static void             pmap_free_pv_chunk(struct pv_chunk *pc);
static void             pmap_free_pv_entry(pmap_t pmap, pv_entry_t pv);
static pv_entry_t       pmap_get_pv_entry(pmap_t pmap, boolean_t try);
static vm_page_t        pmap_pv_reclaim(pmap_t locked_pmap);

static void             pmap_enter_locked(pmap_t, vm_offset_t, vm_page_t,
    vm_prot_t, boolean_t, int);
static vm_paddr_t       pmap_extract_locked(pmap_t pmap, vm_offset_t va);
static void             pmap_alloc_l1(pmap_t);
static void             pmap_free_l1(pmap_t);

static int              pmap_clearbit(struct vm_page *, u_int);

static struct l2_bucket *pmap_get_l2_bucket(pmap_t, vm_offset_t);
static struct l2_bucket *pmap_alloc_l2_bucket(pmap_t, vm_offset_t);
static void             pmap_free_l2_bucket(pmap_t, struct l2_bucket *, u_int);
static vm_offset_t      kernel_pt_lookup(vm_paddr_t);

static MALLOC_DEFINE(M_VMPMAP, "pmap", "PMAP L1");

vm_offset_t virtual_avail;      /* VA of first avail page (after kernel bss) */
vm_offset_t virtual_end;        /* VA of last avail page (end of kernel AS) */
vm_offset_t pmap_curmaxkvaddr;
vm_paddr_t kernel_l1pa;

vm_offset_t kernel_vm_end = 0;

vm_offset_t vm_max_kernel_address;

struct pmap kernel_pmap_store;

static pt_entry_t *csrc_pte, *cdst_pte;
static vm_offset_t csrcp, cdstp;
static struct mtx cmtx;

static void             pmap_init_l1(struct l1_ttable *, pd_entry_t *);
/*
 * These routines are called when the CPU type is identified to set up
 * the PTE prototypes, cache modes, etc.
 *
 * The variables are always here, just in case LKMs need to reference
 * them (though, they shouldn't).
 */
static void pmap_set_prot(pt_entry_t *pte, vm_prot_t prot, uint8_t user);
pt_entry_t      pte_l1_s_cache_mode;
pt_entry_t      pte_l1_s_cache_mode_pt;

pt_entry_t      pte_l2_l_cache_mode;
pt_entry_t      pte_l2_l_cache_mode_pt;

pt_entry_t      pte_l2_s_cache_mode;
pt_entry_t      pte_l2_s_cache_mode_pt;

struct msgbuf *msgbufp = 0;

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

extern void bcopy_page(vm_offset_t, vm_offset_t);
extern void bzero_page(vm_offset_t);

char *_tmppt;

/*
 * Metadata for L1 translation tables.
 */
struct l1_ttable {
        /* Entry on the L1 Table list */
        SLIST_ENTRY(l1_ttable) l1_link;

        /* Entry on the L1 Least Recently Used list */
        TAILQ_ENTRY(l1_ttable) l1_lru;

        /* Track how many domains are allocated from this L1 */
        volatile u_int l1_domain_use_count;

        /*
         * A free-list of domain numbers for this L1.
         * We avoid using ffs() and a bitmap to track domains since ffs()
         * is slow on ARM.
         */
        u_int8_t l1_domain_first;
        u_int8_t l1_domain_free[PMAP_DOMAINS];

        /* Physical address of this L1 page table */
        vm_paddr_t l1_physaddr;

        /* KVA of this L1 page table */
        pd_entry_t *l1_kva;
};

/*
 * Convert a virtual address into its L1 table index. That is, the
 * index used to locate the L2 descriptor table pointer in an L1 table.
 * This is basically used to index l1->l1_kva[].
 *
 * Each L2 descriptor table represents 1MB of VA space.
 */
#define L1_IDX(va)              (((vm_offset_t)(va)) >> L1_S_SHIFT)

/*
 * L1 Page Tables are tracked using a Least Recently Used list.
 *  - New L1s are allocated from the HEAD.
 *  - Freed L1s are added to the TAIl.
 *  - Recently accessed L1s (where an 'access' is some change to one of
 *    the userland pmaps which owns this L1) are moved to the TAIL.
 */
static TAILQ_HEAD(, l1_ttable) l1_lru_list;
/*
 * A list of all L1 tables
 */
static SLIST_HEAD(, l1_ttable) l1_list;
static struct mtx l1_lru_lock;

/*
 * The l2_dtable tracks L2_BUCKET_SIZE worth of L1 slots.
 *
 * This is normally 16MB worth L2 page descriptors for any given pmap.
 * Reference counts are maintained for L2 descriptors so they can be
 * freed when empty.
 */
struct l2_dtable {
        /* The number of L2 page descriptors allocated to this l2_dtable */
        u_int l2_occupancy;

        /* List of L2 page descriptors */
        struct l2_bucket {
                pt_entry_t *l2b_kva;    /* KVA of L2 Descriptor Table */
                vm_paddr_t l2b_phys;    /* Physical address of same */
                u_short l2b_l1idx;      /* This L2 table's L1 index */
                u_short l2b_occupancy;  /* How many active descriptors */
        } l2_bucket[L2_BUCKET_SIZE];
};

/* pmap_kenter_internal flags */
#define KENTER_CACHE    0x1
#define KENTER_USER     0x2

/*
 * Given an L1 table index, calculate the corresponding l2_dtable index
 * and bucket index within the l2_dtable.
 */
#define L2_IDX(l1idx)           (((l1idx) >> L2_BUCKET_LOG2) & \
                                 (L2_SIZE - 1))
#define L2_BUCKET(l1idx)        ((l1idx) & (L2_BUCKET_SIZE - 1))

/*
 * Given a virtual address, this macro returns the
 * virtual address required to drop into the next L2 bucket.
 */
#define L2_NEXT_BUCKET(va)      (((va) & L1_S_FRAME) + L1_S_SIZE)

/*
 * We try to map the page tables write-through, if possible.  However, not
 * all CPUs have a write-through cache mode, so on those we have to sync
 * the cache when we frob page tables.
 *
 * We try to evaluate this at compile time, if possible.  However, it's
 * not always possible to do that, hence this run-time var.
 */
int     pmap_needs_pte_sync;

/*
 * Macro to determine if a mapping might be resident in the
 * instruction cache and/or TLB
 */
#define PV_BEEN_EXECD(f)  (((f) & (PVF_REF | PVF_EXEC)) == (PVF_REF | PVF_EXEC))

/*
 * Macro to determine if a mapping might be resident in the
 * data cache and/or TLB
 */
#define PV_BEEN_REFD(f)   (((f) & PVF_REF) != 0)

#ifndef PMAP_SHPGPERPROC
#define PMAP_SHPGPERPROC 200
#endif

#define pmap_is_current(pm)     ((pm) == pmap_kernel() || \
            curproc->p_vmspace->vm_map.pmap == (pm))

/*
 * Data for the pv entry allocation mechanism
 */
static TAILQ_HEAD(pch, pv_chunk) pv_chunks = TAILQ_HEAD_INITIALIZER(pv_chunks);
static int pv_entry_count, pv_entry_max, pv_entry_high_water;
static int shpgperproc = PMAP_SHPGPERPROC;

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

static __inline struct pv_chunk *
pv_to_chunk(pv_entry_t pv)
{

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

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

CTASSERT(sizeof(struct pv_chunk) == PAGE_SIZE);
CTASSERT(_NPCM == 8);
CTASSERT(_NPCPV == 252);

#define PC_FREE0_6      0xfffffffful    /* Free values for index 0 through 6 */
#define PC_FREE7        0x0ffffffful    /* Free values for index 7 */

static const uint32_t pc_freemask[_NPCM] = {
        PC_FREE0_6, PC_FREE0_6, PC_FREE0_6,
        PC_FREE0_6, PC_FREE0_6, PC_FREE0_6,
        PC_FREE0_6, PC_FREE7
};

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

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

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

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

static long pv_entry_frees, pv_entry_allocs;
static int pv_entry_spare;

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

uma_zone_t l2zone;
static uma_zone_t l2table_zone;
static vm_offset_t pmap_kernel_l2dtable_kva;
static vm_offset_t pmap_kernel_l2ptp_kva;
static vm_paddr_t pmap_kernel_l2ptp_phys;
static struct rwlock pvh_global_lock;

int l1_mem_types[] = {
        ARM_L1S_STRONG_ORD,
        ARM_L1S_DEVICE_NOSHARE,
        ARM_L1S_DEVICE_SHARE,
        ARM_L1S_NRML_NOCACHE,
        ARM_L1S_NRML_IWT_OWT,
        ARM_L1S_NRML_IWB_OWB,
        ARM_L1S_NRML_IWBA_OWBA
};

int l2l_mem_types[] = {
        ARM_L2L_STRONG_ORD,
        ARM_L2L_DEVICE_NOSHARE,
        ARM_L2L_DEVICE_SHARE,
        ARM_L2L_NRML_NOCACHE,
        ARM_L2L_NRML_IWT_OWT,
        ARM_L2L_NRML_IWB_OWB,
        ARM_L2L_NRML_IWBA_OWBA
};

int l2s_mem_types[] = {
        ARM_L2S_STRONG_ORD,
        ARM_L2S_DEVICE_NOSHARE,
        ARM_L2S_DEVICE_SHARE,
        ARM_L2S_NRML_NOCACHE,
        ARM_L2S_NRML_IWT_OWT,
        ARM_L2S_NRML_IWB_OWB,
        ARM_L2S_NRML_IWBA_OWBA
};

/*
 * This list exists for the benefit of pmap_map_chunk().  It keeps track
 * of the kernel L2 tables during bootstrap, so that pmap_map_chunk() can
 * find them as necessary.
 *
 * Note that the data on this list MUST remain valid after initarm() returns,
 * as pmap_bootstrap() uses it to contruct L2 table metadata.
 */
SLIST_HEAD(, pv_addr) kernel_pt_list = SLIST_HEAD_INITIALIZER(kernel_pt_list);

static void
pmap_init_l1(struct l1_ttable *l1, pd_entry_t *l1pt)
{
        int i;

        l1->l1_kva = l1pt;
        l1->l1_domain_use_count = 0;
        l1->l1_domain_first = 0;

        for (i = 0; i < PMAP_DOMAINS; i++)
                l1->l1_domain_free[i] = i + 1;

        /*
         * Copy the kernel's L1 entries to each new L1.
         */
        if (l1pt != pmap_kernel()->pm_l1->l1_kva)
                memcpy(l1pt, pmap_kernel()->pm_l1->l1_kva, L1_TABLE_SIZE);

        if ((l1->l1_physaddr = pmap_extract(pmap_kernel(), (vm_offset_t)l1pt)) == 0)
                panic("pmap_init_l1: can't get PA of L1 at %p", l1pt);
        SLIST_INSERT_HEAD(&l1_list, l1, l1_link);
        TAILQ_INSERT_TAIL(&l1_lru_list, l1, l1_lru);
}

static vm_offset_t
kernel_pt_lookup(vm_paddr_t pa)
{
        struct pv_addr *pv;

        SLIST_FOREACH(pv, &kernel_pt_list, pv_list) {
                if (pv->pv_pa == pa)
                        return (pv->pv_va);
        }
        return (0);
}

void
pmap_pte_init_mmu_v6(void)
{

        if (PTE_PAGETABLE >= 3)
                pmap_needs_pte_sync = 1;
        pte_l1_s_cache_mode = l1_mem_types[PTE_CACHE];
        pte_l2_l_cache_mode = l2l_mem_types[PTE_CACHE];
        pte_l2_s_cache_mode = l2s_mem_types[PTE_CACHE];

        pte_l1_s_cache_mode_pt = l1_mem_types[PTE_PAGETABLE];
        pte_l2_l_cache_mode_pt = l2l_mem_types[PTE_PAGETABLE];
        pte_l2_s_cache_mode_pt = l2s_mem_types[PTE_PAGETABLE];

}

/*
 * Allocate an L1 translation table for the specified pmap.
 * This is called at pmap creation time.
 */
static void
pmap_alloc_l1(pmap_t pm)
{
        struct l1_ttable *l1;
        u_int8_t domain;

        /*
         * Remove the L1 at the head of the LRU list
         */
        mtx_lock(&l1_lru_lock);
        l1 = TAILQ_FIRST(&l1_lru_list);
        TAILQ_REMOVE(&l1_lru_list, l1, l1_lru);

        /*
         * Pick the first available domain number, and update
         * the link to the next number.
         */
        domain = l1->l1_domain_first;
        l1->l1_domain_first = l1->l1_domain_free[domain];

        /*
         * If there are still free domain numbers in this L1,
         * put it back on the TAIL of the LRU list.
         */
        if (++l1->l1_domain_use_count < PMAP_DOMAINS)
                TAILQ_INSERT_TAIL(&l1_lru_list, l1, l1_lru);

        mtx_unlock(&l1_lru_lock);

        /*
         * Fix up the relevant bits in the pmap structure
         */
        pm->pm_l1 = l1;
        pm->pm_domain = domain + 1;
}

/*
 * Free an L1 translation table.
 * This is called at pmap destruction time.
 */
static void
pmap_free_l1(pmap_t pm)
{
        struct l1_ttable *l1 = pm->pm_l1;

        mtx_lock(&l1_lru_lock);

        /*
         * If this L1 is currently on the LRU list, remove it.
         */
        if (l1->l1_domain_use_count < PMAP_DOMAINS)
                TAILQ_REMOVE(&l1_lru_list, l1, l1_lru);

        /*
         * Free up the domain number which was allocated to the pmap
         */
        l1->l1_domain_free[pm->pm_domain - 1] = l1->l1_domain_first;
        l1->l1_domain_first = pm->pm_domain - 1;
        l1->l1_domain_use_count--;

        /*
         * The L1 now must have at least 1 free domain, so add
         * it back to the LRU list. If the use count is zero,
         * put it at the head of the list, otherwise it goes
         * to the tail.
         */
        if (l1->l1_domain_use_count == 0) {
                TAILQ_INSERT_HEAD(&l1_lru_list, l1, l1_lru);
        }       else
                TAILQ_INSERT_TAIL(&l1_lru_list, l1, l1_lru);

        mtx_unlock(&l1_lru_lock);
}

/*
 * Returns a pointer to the L2 bucket associated with the specified pmap
 * and VA, or NULL if no L2 bucket exists for the address.
 */
static PMAP_INLINE struct l2_bucket *
pmap_get_l2_bucket(pmap_t pm, vm_offset_t va)
{
        struct l2_dtable *l2;
        struct l2_bucket *l2b;
        u_short l1idx;

        l1idx = L1_IDX(va);

        if ((l2 = pm->pm_l2[L2_IDX(l1idx)]) == NULL ||
            (l2b = &l2->l2_bucket[L2_BUCKET(l1idx)])->l2b_kva == NULL)
                return (NULL);

        return (l2b);
}

/*
 * Returns a pointer to the L2 bucket associated with the specified pmap
 * and VA.
 *
 * If no L2 bucket exists, perform the necessary allocations to put an L2
 * bucket/page table in place.
 *
 * Note that if a new L2 bucket/page was allocated, the caller *must*
 * increment the bucket occupancy counter appropriately *before*
 * releasing the pmap's lock to ensure no other thread or cpu deallocates
 * the bucket/page in the meantime.
 */
static struct l2_bucket *
pmap_alloc_l2_bucket(pmap_t pm, vm_offset_t va)
{
        struct l2_dtable *l2;
        struct l2_bucket *l2b;
        u_short l1idx;

        l1idx = L1_IDX(va);

        PMAP_ASSERT_LOCKED(pm);
        rw_assert(&pvh_global_lock, RA_WLOCKED);
        if ((l2 = pm->pm_l2[L2_IDX(l1idx)]) == NULL) {
                /*
                 * No mapping at this address, as there is
                 * no entry in the L1 table.
                 * Need to allocate a new l2_dtable.
                 */
                PMAP_UNLOCK(pm);
                rw_wunlock(&pvh_global_lock);
                if ((l2 = uma_zalloc(l2table_zone, M_NOWAIT)) == NULL) {
                        rw_wlock(&pvh_global_lock);
                        PMAP_LOCK(pm);
                        return (NULL);
                }
                rw_wlock(&pvh_global_lock);
                PMAP_LOCK(pm);
                if (pm->pm_l2[L2_IDX(l1idx)] != NULL) {
                        /*
                         * Someone already allocated the l2_dtable while
                         * we were doing the same.
                         */
                        uma_zfree(l2table_zone, l2);
                        l2 = pm->pm_l2[L2_IDX(l1idx)];
                } else {
                        bzero(l2, sizeof(*l2));
                        /*
                         * Link it into the parent pmap
                         */
                        pm->pm_l2[L2_IDX(l1idx)] = l2;
                }
        }

        l2b = &l2->l2_bucket[L2_BUCKET(l1idx)];

        /*
         * Fetch pointer to the L2 page table associated with the address.
         */
        if (l2b->l2b_kva == NULL) {
                pt_entry_t *ptep;

                /*
                 * No L2 page table has been allocated. Chances are, this
                 * is because we just allocated the l2_dtable, above.
                 */
                PMAP_UNLOCK(pm);
                rw_wunlock(&pvh_global_lock);
                ptep = uma_zalloc(l2zone, M_NOWAIT);
                rw_wlock(&pvh_global_lock);
                PMAP_LOCK(pm);
                if (l2b->l2b_kva != 0) {
                        /* We lost the race. */
                        uma_zfree(l2zone, ptep);
                        return (l2b);
                }
                l2b->l2b_phys = vtophys(ptep);
                if (ptep == NULL) {
                        /*
                         * Oops, no more L2 page tables available at this
                         * time. We may need to deallocate the l2_dtable
                         * if we allocated a new one above.
                         */
                        if (l2->l2_occupancy == 0) {
                                pm->pm_l2[L2_IDX(l1idx)] = NULL;
                                uma_zfree(l2table_zone, l2);
                        }
                        return (NULL);
                }

                l2->l2_occupancy++;
                l2b->l2b_kva = ptep;
                l2b->l2b_l1idx = l1idx;
        }

        return (l2b);
}

static PMAP_INLINE void
pmap_free_l2_ptp(pt_entry_t *l2)
{
        uma_zfree(l2zone, l2);
}
/*
 * One or more mappings in the specified L2 descriptor table have just been
 * invalidated.
 *
 * Garbage collect the metadata and descriptor table itself if necessary.
 *
 * The pmap lock must be acquired when this is called (not necessary
 * for the kernel pmap).
 */
static void
pmap_free_l2_bucket(pmap_t pm, struct l2_bucket *l2b, u_int count)
{
        struct l2_dtable *l2;
        pd_entry_t *pl1pd, l1pd;
        pt_entry_t *ptep;
        u_short l1idx;


        /*
         * Update the bucket's reference count according to how many
         * PTEs the caller has just invalidated.
         */
        l2b->l2b_occupancy -= count;

        /*
         * Note:
         *
         * Level 2 page tables allocated to the kernel pmap are never freed
         * as that would require checking all Level 1 page tables and
         * removing any references to the Level 2 page table. See also the
         * comment elsewhere about never freeing bootstrap L2 descriptors.
         *
         * We make do with just invalidating the mapping in the L2 table.
         *
         * This isn't really a big deal in practice and, in fact, leads
         * to a performance win over time as we don't need to continually
         * alloc/free.
         */
        if (l2b->l2b_occupancy > 0 || pm == pmap_kernel())
                return;

        /*
         * There are no more valid mappings in this level 2 page table.
         * Go ahead and NULL-out the pointer in the bucket, then
         * free the page table.
         */
        l1idx = l2b->l2b_l1idx;
        ptep = l2b->l2b_kva;
        l2b->l2b_kva = NULL;

        pl1pd = &pm->pm_l1->l1_kva[l1idx];

        /*
         * If the L1 slot matches the pmap's domain
         * number, then invalidate it.
         */
        l1pd = *pl1pd & (L1_TYPE_MASK | L1_C_DOM_MASK);
        if (l1pd == (L1_C_DOM(pm->pm_domain) | L1_TYPE_C)) {
                *pl1pd = 0;
                PTE_SYNC(pl1pd);
        }

        /*
         * Release the L2 descriptor table back to the pool cache.
         */
        pmap_free_l2_ptp(ptep);

        /*
         * Update the reference count in the associated l2_dtable
         */
        l2 = pm->pm_l2[L2_IDX(l1idx)];
        if (--l2->l2_occupancy > 0)
                return;

        /*
         * There are no more valid mappings in any of the Level 1
         * slots managed by this l2_dtable. Go ahead and NULL-out
         * the pointer in the parent pmap and free the l2_dtable.
         */
        pm->pm_l2[L2_IDX(l1idx)] = NULL;
        uma_zfree(l2table_zone, l2);
}

/*
 * Pool cache constructors for L2 descriptor tables, metadata and pmap
 * structures.
 */
static int
pmap_l2ptp_ctor(void *mem, int size, void *arg, int flags)
{
        struct l2_bucket *l2b;
        pt_entry_t *ptep, pte;
        vm_offset_t va = (vm_offset_t)mem & ~PAGE_MASK;

        /*
         * The mappings for these page tables were initially made using
         * pmap_kenter() by the pool subsystem. Therefore, the cache-
         * mode will not be right for page table mappings. To avoid
         * polluting the pmap_kenter() code with a special case for
         * page tables, we simply fix up the cache-mode here if it's not
         * correct.
         */
        l2b = pmap_get_l2_bucket(pmap_kernel(), va);
        ptep = &l2b->l2b_kva[l2pte_index(va)];
        pte = *ptep;

        cpu_idcache_wbinv_range(va, PAGE_SIZE);
        pmap_l2cache_wbinv_range(va, pte & L2_S_FRAME, PAGE_SIZE);
        if ((pte & L2_S_CACHE_MASK) != pte_l2_s_cache_mode_pt) {
                /*
                 * Page tables must have the cache-mode set to
                 * Write-Thru.
                 */
                *ptep = (pte & ~L2_S_CACHE_MASK) | pte_l2_s_cache_mode_pt;
                PTE_SYNC(ptep);
                cpu_tlb_flushD_SE(va);
                cpu_cpwait();
        }

        memset(mem, 0, L2_TABLE_SIZE_REAL);
        return (0);
}

/*
 * Modify pte bits for all ptes corresponding to the given physical address.
 * We use `maskbits' rather than `clearbits' because we're always passing
 * constants and the latter would require an extra inversion at run-time.
 */
static int
pmap_clearbit(struct vm_page *pg, u_int maskbits)
{
        struct l2_bucket *l2b;
        struct pv_entry *pv;
        pt_entry_t *ptep, npte, opte;
        pmap_t pm;
        vm_offset_t va;
        u_int oflags;
        int count = 0;

        rw_wlock(&pvh_global_lock);

        if (maskbits & PVF_WRITE)
                maskbits |= PVF_MOD;
        /*
         * Clear saved attributes (modify, reference)
         */
        pg->md.pvh_attrs &= ~(maskbits & (PVF_MOD | PVF_REF));

        if (TAILQ_EMPTY(&pg->md.pv_list)) {
                rw_wunlock(&pvh_global_lock);
                return (0);
        }

        /*
         * Loop over all current mappings setting/clearing as appropos
         */
        TAILQ_FOREACH(pv, &pg->md.pv_list, pv_list) {
                va = pv->pv_va;
                pm = PV_PMAP(pv);
                oflags = pv->pv_flags;
                pv->pv_flags &= ~maskbits;

                PMAP_LOCK(pm);

                l2b = pmap_get_l2_bucket(pm, va);

                ptep = &l2b->l2b_kva[l2pte_index(va)];
                npte = opte = *ptep;

                if ((maskbits & (PVF_WRITE|PVF_MOD)) && L2_S_WRITABLE(opte)) {
                        vm_page_dirty(pg);

                        /* make the pte read only */
                        npte |= L2_APX;
                }

                if (maskbits & PVF_REF) {
                        /*
                         * Make the PTE invalid so that we will take a
                         * page fault the next time the mapping is
                         * referenced.
                         */
                        npte &= ~L2_TYPE_MASK;
                        npte |= L2_TYPE_INV;
                }

                CTR4(KTR_PMAP,"clearbit: pmap:%p bits:%x pte:%x->%x",
                    pm, maskbits, opte, npte);
                if (npte != opte) {
                        count++;
                        *ptep = npte;
                        PTE_SYNC(ptep);
                        /* Flush the TLB entry if a current pmap. */
                        if (PV_BEEN_EXECD(oflags))
                                cpu_tlb_flushID_SE(pv->pv_va);
                        else if (PV_BEEN_REFD(oflags))
                                cpu_tlb_flushD_SE(pv->pv_va);
                }

                PMAP_UNLOCK(pm);

        }

        if (maskbits & PVF_WRITE)
                vm_page_aflag_clear(pg, PGA_WRITEABLE);
        rw_wunlock(&pvh_global_lock);
        return (count);
}

/*
 * main pv_entry manipulation functions:
 *   pmap_enter_pv: enter a mapping onto a vm_page list
 *   pmap_remove_pv: remove a mappiing from a vm_page list
 *
 * NOTE: pmap_enter_pv expects to lock the pvh itself
 *       pmap_remove_pv expects the caller to lock the pvh before calling
 */

/*
 * pmap_enter_pv: enter a mapping onto a vm_page's PV list
 *
 * => caller should hold the proper lock on pvh_global_lock
 * => caller should have pmap locked
 * => we will (someday) gain the lock on the vm_page's PV list
 * => caller should adjust ptp's wire_count before calling
 * => caller should not adjust pmap's wire_count
 */
static void
pmap_enter_pv(struct vm_page *pg, struct pv_entry *pve, pmap_t pm,
    vm_offset_t va, u_int flags)
{

        rw_assert(&pvh_global_lock, RA_WLOCKED);

        PMAP_ASSERT_LOCKED(pm);
        pve->pv_va = va;
        pve->pv_flags = flags;

        TAILQ_INSERT_HEAD(&pg->md.pv_list, pve, pv_list);
        pg->md.pvh_attrs |= flags & (PVF_REF | PVF_MOD);
        if (pve->pv_flags & PVF_WIRED)
                ++pm->pm_stats.wired_count;
        vm_page_aflag_set(pg, PGA_REFERENCED);
}

/*
 *
 * pmap_find_pv: Find a pv entry
 *
 * => caller should hold lock on vm_page
 */
static PMAP_INLINE struct pv_entry *
pmap_find_pv(struct vm_page *pg, pmap_t pm, vm_offset_t va)
{
        struct pv_entry *pv;

        rw_assert(&pvh_global_lock, RA_WLOCKED);
        TAILQ_FOREACH(pv, &pg->md.pv_list, pv_list)
            if (pm == PV_PMAP(pv) && va == pv->pv_va)
                    break;
        return (pv);
}

/*
 * vector_page_setprot:
 *
 *      Manipulate the protection of the vector page.
 */
void
vector_page_setprot(int prot)
{
        struct l2_bucket *l2b;
        pt_entry_t *ptep;

        l2b = pmap_get_l2_bucket(pmap_kernel(), vector_page);

        ptep = &l2b->l2b_kva[l2pte_index(vector_page)];

        pmap_set_prot(ptep, prot|VM_PROT_EXECUTE, 0);

        cpu_tlb_flushD_SE(vector_page);
        cpu_cpwait();
}

static void
pmap_set_prot(pt_entry_t *ptep, vm_prot_t prot, uint8_t user)
{

        *ptep &= ~L2_S_PROT_MASK;

        if (!(prot & VM_PROT_EXECUTE))
                *ptep |= L2_XN;

        *ptep |= L2_APX;
        *ptep |= L2_S_PROT_R;

        if (user)
                *ptep |= L2_S_PROT_U;

        if (prot & VM_PROT_WRITE)
                *ptep &= ~(L2_APX);
        else if (user)
                *ptep &= ~(L2_S_PROT_R);
}

/*
 * pmap_remove_pv: try to remove a mapping from a pv_list
 *
 * => caller should hold proper lock on pmap_main_lock
 * => pmap should be locked
 * => caller should hold lock on vm_page [so that attrs can be adjusted]
 * => caller should adjust ptp's wire_count and free PTP if needed
 * => caller should NOT adjust pmap's wire_count
 * => we return the removed pve
 */

static void
pmap_nuke_pv(struct vm_page *pg, pmap_t pm, struct pv_entry *pve)
{

        rw_assert(&pvh_global_lock, RA_WLOCKED);
        PMAP_ASSERT_LOCKED(pm);

        TAILQ_REMOVE(&pg->md.pv_list, pve, pv_list);

        if (pve->pv_flags & PVF_WIRED)
                --pm->pm_stats.wired_count;

        if (pg->md.pvh_attrs & PVF_MOD)
                vm_page_dirty(pg);

        if (TAILQ_FIRST(&pg->md.pv_list) == NULL)
                pg->md.pvh_attrs &= ~PVF_REF;
        else
                vm_page_aflag_set(pg, PGA_REFERENCED);

        if (pve->pv_flags & PVF_WRITE) {
                TAILQ_FOREACH(pve, &pg->md.pv_list, pv_list)
                    if (pve->pv_flags & PVF_WRITE)
                            break;
                if (!pve) {
                        pg->md.pvh_attrs &= ~PVF_MOD;
                        vm_page_aflag_clear(pg, PGA_WRITEABLE);
                }
        }
}

static struct pv_entry *
pmap_remove_pv(struct vm_page *pg, pmap_t pm, vm_offset_t va)
{
        struct pv_entry *pve;

        rw_assert(&pvh_global_lock, RA_WLOCKED);
        pve = TAILQ_FIRST(&pg->md.pv_list);

        while (pve) {
                if (PV_PMAP(pve) == pm && pve->pv_va == va) {   /* match? */
                        pmap_nuke_pv(pg, pm, pve);
                        break;
                }
                pve = TAILQ_NEXT(pve, pv_list);
        }

        return(pve);                            /* return removed pve */
}

/*
 *
 * pmap_modify_pv: Update pv flags
 *
 * => caller should hold lock on vm_page [so that attrs can be adjusted]
 * => caller should NOT adjust pmap's wire_count
 * => we return the old flags
 *
 * Modify a physical-virtual mapping in the pv table
 */
static u_int
pmap_modify_pv(struct vm_page *pg, pmap_t pm, vm_offset_t va,
    u_int clr_mask, u_int set_mask)
{
        struct pv_entry *npv;
        u_int flags, oflags;

        PMAP_ASSERT_LOCKED(pm);
        rw_assert(&pvh_global_lock, RA_WLOCKED);
        if ((npv = pmap_find_pv(pg, pm, va)) == NULL)
                return (0);

        /*
         * There is at least one VA mapping this page.
         */

        if (clr_mask & (PVF_REF | PVF_MOD))
                pg->md.pvh_attrs |= set_mask & (PVF_REF | PVF_MOD);

        oflags = npv->pv_flags;
        npv->pv_flags = flags = (oflags & ~clr_mask) | set_mask;

        if ((flags ^ oflags) & PVF_WIRED) {
                if (flags & PVF_WIRED)
                        ++pm->pm_stats.wired_count;
                else
                        --pm->pm_stats.wired_count;
        }
        if ((oflags & PVF_WRITE) && !(flags & PVF_WRITE)) {
                TAILQ_FOREACH(npv, &pg->md.pv_list, pv_list) {
                        if (npv->pv_flags & PVF_WRITE)
                                break;
                }
                if (!npv) {
                        pg->md.pvh_attrs &= ~PVF_MOD;
                        vm_page_aflag_clear(pg, PGA_WRITEABLE);
                }
        }

        return (oflags);
}

/* Function to set the debug level of the pmap code */
#ifdef PMAP_DEBUG
void
pmap_debug(int level)
{
        pmap_debug_level = level;
        dprintf("pmap_debug: level=%d\n", pmap_debug_level);
}
#endif  /* PMAP_DEBUG */

void
pmap_pinit0(struct pmap *pmap)
{
        PDEBUG(1, printf("pmap_pinit0: pmap = %08x\n", (u_int32_t) pmap));

        dprintf("pmap_pinit0: pmap = %08x, pm_pdir = %08x\n",
                (u_int32_t) pmap, (u_int32_t) pmap->pm_pdir);
        bcopy(kernel_pmap, pmap, sizeof(*pmap));
        bzero(&pmap->pm_mtx, sizeof(pmap->pm_mtx));
        PMAP_LOCK_INIT(pmap);
}

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

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

static vm_offset_t
pmap_ptelist_alloc(vm_offset_t *head)
{
        pt_entry_t *pte;
        vm_offset_t va;

        va = *head;
        if (va == 0)
                return (va);    /* Out of memory */
        pte = vtopte(va);
        *head = *pte;
        if ((*head & L2_TYPE_MASK) != L2_TYPE_INV)
                panic("%s: va is not L2_TYPE_INV!", __func__);
        *pte = 0;
        return (va);
}

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

        if ((va & L2_TYPE_MASK) != L2_TYPE_INV)
                panic("%s: freeing va that is not L2_TYPE INV!", __func__);
        pte = vtopte(va);
        *pte = *head;           /* virtual! L2_TYPE is L2_TYPE_INV though */
        *head = va;
}

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

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

/*
 *      Initialize the pmap module.
 *      Called by vm_init, to initialize any structures that the pmap
 *      system needs to map virtual memory.
 */
void
pmap_init(void)
{

        PDEBUG(1, printf("pmap_init: phys_start = %08x\n", PHYSADDR));

        l2zone = uma_zcreate("L2 Table", L2_TABLE_SIZE_REAL, pmap_l2ptp_ctor,
            NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM | UMA_ZONE_NOFREE);
        l2table_zone = uma_zcreate("L2 Table", sizeof(struct l2_dtable), NULL,
            NULL, NULL, NULL, UMA_ALIGN_PTR, UMA_ZONE_VM | UMA_ZONE_NOFREE);

        /*
         * Initialize the address space for the pv chunks.
         */

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

        pv_maxchunks = MAX(pv_entry_max / _NPCPV, maxproc);
        pv_chunkbase = (struct pv_chunk *)kmem_alloc_nofault(kernel_map,
            PAGE_SIZE * pv_maxchunks);

        if (pv_chunkbase == NULL)
                panic("pmap_init: not enough kvm for pv chunks");

        pmap_ptelist_init(&pv_vafree, pv_chunkbase, pv_maxchunks);

        /*
         * Now it is safe to enable pv_table recording.
         */
        PDEBUG(1, printf("pmap_init: done!\n"));
}

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

int
pmap_fault_fixup(pmap_t pm, vm_offset_t va, vm_prot_t ftype, int user)
{
        struct l2_dtable *l2;
        struct l2_bucket *l2b;
        pd_entry_t *pl1pd, l1pd;
        pt_entry_t *ptep, pte;
        vm_paddr_t pa;
        u_int l1idx;
        int rv = 0;

        l1idx = L1_IDX(va);
        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pm);

        /*
         * If there is no l2_dtable for this address, then the process
         * has no business accessing it.
         *
         * Note: This will catch userland processes trying to access
         * kernel addresses.
         */
        l2 = pm->pm_l2[L2_IDX(l1idx)];
        if (l2 == NULL)
                goto out;

        /*
         * Likewise if there is no L2 descriptor table
         */
        l2b = &l2->l2_bucket[L2_BUCKET(l1idx)];
        if (l2b->l2b_kva == NULL)
                goto out;

        /*
         * Check the PTE itself.
         */
        ptep = &l2b->l2b_kva[l2pte_index(va)];
        pte = *ptep;
        if (pte == 0)
                goto out;

        /*
         * Catch a userland access to the vector page mapped at 0x0
         */
        if (user && !(pte & L2_S_PROT_U))
                goto out;
        if (va == vector_page)
                goto out;

        pa = l2pte_pa(pte);
        CTR5(KTR_PMAP, "pmap_fault_fix: pmap:%p va:%x pte:0x%x ftype:%x user:%x",
            pm, va, pte, ftype, user);
        if ((ftype & VM_PROT_WRITE) && !(L2_S_WRITABLE(pte))) {
                /*
                 * This looks like a good candidate for "page modified"
                 * emulation...
                 */
                struct pv_entry *pv;
                struct vm_page *pg;

                /* Extract the physical address of the page */
                if ((pg = PHYS_TO_VM_PAGE(pa)) == NULL) {
                        goto out;
                }
                /* Get the current flags for this page. */

                pv = pmap_find_pv(pg, pm, va);
                if (pv == NULL) {
                        goto out;
                }

                /*
                 * Do the flags say this page is writable? If not then it
                 * is a genuine write fault. If yes then the write fault is
                 * our fault as we did not reflect the write access in the
                 * PTE. Now we know a write has occurred we can correct this
                 * and also set the modified bit
                 */
                if ((pv->pv_flags & PVF_WRITE) == 0) {
                        goto out;
                }
                pg->md.pvh_attrs |= PVF_REF | PVF_MOD;
                vm_page_dirty(pg);
                pv->pv_flags |= PVF_REF | PVF_MOD;

                /* Re-enable write permissions for the page */
                *ptep = (pte & ~L2_TYPE_MASK) | L2_S_PROTO;
                pmap_set_prot(ptep, VM_PROT_WRITE, *ptep & L2_S_PROT_U);
                CTR1(KTR_PMAP, "pmap_fault_fix: new pte:0x%x", pte);
                PTE_SYNC(ptep);
                rv = 1;
        } else if ((pte & L2_TYPE_MASK) == L2_TYPE_INV) {
                /*
                 * This looks like a good candidate for "page referenced"
                 * emulation.
                 */
                struct pv_entry *pv;
                struct vm_page *pg;

                /* Extract the physical address of the page */
                if ((pg = PHYS_TO_VM_PAGE(pa)) == NULL)
                        goto out;
                /* Get the current flags for this page. */

                pv = pmap_find_pv(pg, pm, va);
                if (pv == NULL)
                        goto out;

                pg->md.pvh_attrs |= PVF_REF;
                pv->pv_flags |= PVF_REF;


                *ptep = (pte & ~L2_TYPE_MASK) | L2_S_PROTO;
                PTE_SYNC(ptep);
                rv = 1;
        }

        /*
         * We know there is a valid mapping here, so simply
         * fix up the L1 if necessary.
         */
        pl1pd = &pm->pm_l1->l1_kva[l1idx];
        l1pd = l2b->l2b_phys | L1_C_DOM(pm->pm_domain) | L1_C_PROTO;
        if (*pl1pd != l1pd) {
                *pl1pd = l1pd;
                PTE_SYNC(pl1pd);
                rv = 1;
        }

#ifdef DEBUG
        /*
         * If 'rv == 0' at this point, it generally indicates that there is a
         * stale TLB entry for the faulting address. This happens when two or
         * more processes are sharing an L1. Since we don't flush the TLB on
         * a context switch between such processes, we can take domain faults
         * for mappings which exist at the same VA in both processes. EVEN IF
         * WE'VE RECENTLY FIXED UP THE CORRESPONDING L1 in pmap_enter(), for
         * example.
         *
         * This is extremely likely to happen if pmap_enter() updated the L1
         * entry for a recently entered mapping. In this case, the TLB is
         * flushed for the new mapping, but there may still be TLB entries for
         * other mappings belonging to other processes in the 1MB range
         * covered by the L1 entry.
         *
         * Since 'rv == 0', we know that the L1 already contains the correct
         * value, so the fault must be due to a stale TLB entry.
         *
         * Since we always need to flush the TLB anyway in the case where we
         * fixed up the L1, or frobbed the L2 PTE, we effectively deal with
         * stale TLB entries dynamically.
         *
         * However, the above condition can ONLY happen if the current L1 is
         * being shared. If it happens when the L1 is unshared, it indicates
         * that other parts of the pmap are not doing their job WRT managing
         * the TLB.
         */
        if (rv == 0 && pm->pm_l1->l1_domain_use_count == 1) {
                printf("fixup: pm %p, va 0x%08x, ftype %d - nothing to do!\n",
                    pm, va, ftype);
                printf("fixup: l2 %p, l2b %p, ptep %p, pl1pd %p\n",
                    l2, l2b, ptep, pl1pd);
                printf("fixup: pte 0x%x, l1pd 0x%x, last code 0x%x\n",
                    pte, l1pd, last_fault_code);
#ifdef DDB
                Debugger();
#endif
        }
#endif

        cpu_tlb_flushID_SE(va);
        cpu_cpwait();

        rv = 1;

out:
        rw_wunlock(&pvh_global_lock);
        PMAP_UNLOCK(pm);
        return (rv);
}

void
pmap_postinit(void)
{
        struct l2_bucket *l2b;
        struct l1_ttable *l1;
        pd_entry_t *pl1pt;
        pt_entry_t *ptep, pte;
        vm_offset_t va, eva;
        u_int loop, needed;

        needed = (maxproc / PMAP_DOMAINS) + ((maxproc % PMAP_DOMAINS) ? 1 : 0);
        needed -= 1;
        l1 = malloc(sizeof(*l1) * needed, M_VMPMAP, M_WAITOK);

        for (loop = 0; loop < needed; loop++, l1++) {
                /* Allocate a L1 page table */
                va = (vm_offset_t)contigmalloc(L1_TABLE_SIZE, M_VMPMAP, 0, 0x0,
                    0xffffffff, L1_TABLE_SIZE, 0);

                if (va == 0)
                        panic("Cannot allocate L1 KVM");

                eva = va + L1_TABLE_SIZE;
                pl1pt = (pd_entry_t *)va;

                while (va < eva) {
                                l2b = pmap_get_l2_bucket(pmap_kernel(), va);
                                ptep = &l2b->l2b_kva[l2pte_index(va)];
                                pte = *ptep;
                                pte = (pte & ~L2_S_CACHE_MASK) | pte_l2_s_cache_mode_pt;
                                *ptep = pte;
                                PTE_SYNC(ptep);
                                cpu_tlb_flushD_SE(va);

                                va += PAGE_SIZE;
                }
                pmap_init_l1(l1, pl1pt);
        }
#ifdef DEBUG
        printf("pmap_postinit: Allocated %d static L1 descriptor tables\n",
            needed);
#endif
}

/*
 * This is used to stuff certain critical values into the PCB where they
 * can be accessed quickly from cpu_switch() et al.
 */
void
pmap_set_pcb_pagedir(pmap_t pm, struct pcb *pcb)
{
        struct l2_bucket *l2b;

        pcb->pcb_pagedir = pm->pm_l1->l1_physaddr;
        pcb->pcb_dacr = (DOMAIN_CLIENT << (PMAP_DOMAIN_KERNEL * 2)) |
            (DOMAIN_CLIENT << (pm->pm_domain * 2));

        if (vector_page < KERNBASE) {
                pcb->pcb_pl1vec = &pm->pm_l1->l1_kva[L1_IDX(vector_page)];
                l2b = pmap_get_l2_bucket(pm, vector_page);
                pcb->pcb_l1vec = l2b->l2b_phys | L1_C_PROTO |
                    L1_C_DOM(pm->pm_domain) | L1_C_DOM(PMAP_DOMAIN_KERNEL);
        } else
                pcb->pcb_pl1vec = NULL;
}

void
pmap_activate(struct thread *td)
{
        pmap_t pm;
        struct pcb *pcb;

        pm = vmspace_pmap(td->td_proc->p_vmspace);
        pcb = td->td_pcb;

        critical_enter();
        pmap_set_pcb_pagedir(pm, pcb);

        if (td == curthread) {
                u_int cur_dacr, cur_ttb;

                __asm __volatile("mrc p15, 0, %0, c2, c0, 0" : "=r"(cur_ttb));
                __asm __volatile("mrc p15, 0, %0, c3, c0, 0" : "=r"(cur_dacr));

                cur_ttb &= ~(L1_TABLE_SIZE - 1);

                if (cur_ttb == (u_int)pcb->pcb_pagedir &&
                    cur_dacr == pcb->pcb_dacr) {
                        /*
                         * No need to switch address spaces.
                         */
                        critical_exit();
                        return;
                }


                /*
                 * We MUST, I repeat, MUST fix up the L1 entry corresponding
                 * to 'vector_page' in the incoming L1 table before switching
                 * to it otherwise subsequent interrupts/exceptions (including
                 * domain faults!) will jump into hyperspace.
                 */
                if (pcb->pcb_pl1vec) {
                        *pcb->pcb_pl1vec = pcb->pcb_l1vec;
                }

                cpu_domains(pcb->pcb_dacr);
                cpu_setttb(pcb->pcb_pagedir);
        }
        critical_exit();
}

static int
pmap_set_pt_cache_mode(pd_entry_t *kl1, vm_offset_t va)
{
        pd_entry_t *pdep, pde;
        pt_entry_t *ptep, pte;
        vm_offset_t pa;
        int rv = 0;

        /*
         * Make sure the descriptor itself has the correct cache mode
         */
        pdep = &kl1[L1_IDX(va)];
        pde = *pdep;

        if (l1pte_section_p(pde)) {
                if ((pde & L1_S_CACHE_MASK) != pte_l1_s_cache_mode_pt) {
                        *pdep = (pde & ~L1_S_CACHE_MASK) |
                            pte_l1_s_cache_mode_pt;
                        PTE_SYNC(pdep);
                        rv = 1;
                }
        } else {
                pa = (vm_paddr_t)(pde & L1_C_ADDR_MASK);
                ptep = (pt_entry_t *)kernel_pt_lookup(pa);
                if (ptep == NULL)
                        panic("pmap_bootstrap: No L2 for L2 @ va %p\n", ptep);

                ptep = &ptep[l2pte_index(va)];
                pte = *ptep;
                if ((pte & L2_S_CACHE_MASK) != pte_l2_s_cache_mode_pt) {
                        *ptep = (pte & ~L2_S_CACHE_MASK) |
                            pte_l2_s_cache_mode_pt;
                        PTE_SYNC(ptep);
                        rv = 1;
                }
        }

        return (rv);
}

static void
pmap_alloc_specials(vm_offset_t *availp, int pages, vm_offset_t *vap,
    pt_entry_t **ptep)
{
        vm_offset_t va = *availp;
        struct l2_bucket *l2b;

        if (ptep) {
                l2b = pmap_get_l2_bucket(pmap_kernel(), va);
                if (l2b == NULL)
                        panic("pmap_alloc_specials: no l2b for 0x%x", va);

                *ptep = &l2b->l2b_kva[l2pte_index(va)];
        }

        *vap = va;
        *availp = va + (PAGE_SIZE * pages);
}

/*
 *      Bootstrap the system enough to run with virtual memory.
 *
 *      On the arm 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]
 */
#define PMAP_STATIC_L2_SIZE 16

void
pmap_bootstrap(vm_offset_t firstaddr, struct pv_addr *l1pt)
{
        static struct l1_ttable static_l1;
        static struct l2_dtable static_l2[PMAP_STATIC_L2_SIZE];
        struct l1_ttable *l1 = &static_l1;
        struct l2_dtable *l2;
        struct l2_bucket *l2b;
        pd_entry_t pde;
        pd_entry_t *kernel_l1pt = (pd_entry_t *)l1pt->pv_va;
        pt_entry_t *ptep;
        vm_paddr_t pa;
        vm_offset_t va;
        vm_size_t size;
        int l1idx, l2idx, l2next = 0;

        PDEBUG(1, printf("firstaddr = %08x, lastaddr = %08x\n",
            firstaddr, vm_max_kernel_address));

        virtual_avail = firstaddr;
        kernel_pmap->pm_l1 = l1;
        kernel_l1pa = l1pt->pv_pa;

        /*
         * Scan the L1 translation table created by initarm() and create
         * the required metadata for all valid mappings found in it.
         */
        for (l1idx = 0; l1idx < (L1_TABLE_SIZE / sizeof(pd_entry_t)); l1idx++) {
                pde = kernel_l1pt[l1idx];

                /*
                 * We're only interested in Coarse mappings.
                 * pmap_extract() can deal with section mappings without
                 * recourse to checking L2 metadata.
                 */
                if ((pde & L1_TYPE_MASK) != L1_TYPE_C)
                        continue;

                /*
                 * Lookup the KVA of this L2 descriptor table
                 */
                pa = (vm_paddr_t)(pde & L1_C_ADDR_MASK);
                ptep = (pt_entry_t *)kernel_pt_lookup(pa);

                if (ptep == NULL) {
                        panic("pmap_bootstrap: No L2 for va 0x%x, pa 0x%lx",
                            (u_int)l1idx << L1_S_SHIFT, (long unsigned int)pa);
                }

                /*
                 * Fetch the associated L2 metadata structure.
                 * Allocate a new one if necessary.
                 */
                if ((l2 = kernel_pmap->pm_l2[L2_IDX(l1idx)]) == NULL) {
                        if (l2next == PMAP_STATIC_L2_SIZE)
                                panic("pmap_bootstrap: out of static L2s");
                        kernel_pmap->pm_l2[L2_IDX(l1idx)] = l2 =
                            &static_l2[l2next++];
                }

                /*
                 * One more L1 slot tracked...
                 */
                l2->l2_occupancy++;

                /*
                 * Fill in the details of the L2 descriptor in the
                 * appropriate bucket.
                 */
                l2b = &l2->l2_bucket[L2_BUCKET(l1idx)];
                l2b->l2b_kva = ptep;
                l2b->l2b_phys = pa;
                l2b->l2b_l1idx = l1idx;

                /*
                 * Establish an initial occupancy count for this descriptor
                 */
                for (l2idx = 0;
                    l2idx < (L2_TABLE_SIZE_REAL / sizeof(pt_entry_t));
                    l2idx++) {
                        if ((ptep[l2idx] & L2_TYPE_MASK) != L2_TYPE_INV) {
                                l2b->l2b_occupancy++;
                        }
                }

                /*
                 * Make sure the descriptor itself has the correct cache mode.
                 * If not, fix it, but whine about the problem. Port-meisters
                 * should consider this a clue to fix up their initarm()
                 * function. :)
                 */
                if (pmap_set_pt_cache_mode(kernel_l1pt, (vm_offset_t)ptep)) {
                        printf("pmap_bootstrap: WARNING! wrong cache mode for "
                            "L2 pte @ %p\n", ptep);
                }
        }


        /*
         * Ensure the primary (kernel) L1 has the correct cache mode for
         * a page table. Bitch if it is not correctly set.
         */
        for (va = (vm_offset_t)kernel_l1pt;
            va < ((vm_offset_t)kernel_l1pt + L1_TABLE_SIZE); va += PAGE_SIZE) {
                if (pmap_set_pt_cache_mode(kernel_l1pt, va))
                        printf("pmap_bootstrap: WARNING! wrong cache mode for "
                            "primary L1 @ 0x%x\n", va);
        }

        cpu_dcache_wbinv_all();
        cpu_l2cache_wbinv_all();
        cpu_tlb_flushID();
        cpu_cpwait();

        PMAP_LOCK_INIT(kernel_pmap);
        CPU_FILL(&kernel_pmap->pm_active);
        kernel_pmap->pm_domain = PMAP_DOMAIN_KERNEL;
        TAILQ_INIT(&kernel_pmap->pm_pvchunk);

        /*
         * Initialize the global pv list lock.
         */
        rw_init(&pvh_global_lock, "pmap pv global");

        /*
         * Reserve some special page table entries/VA space for temporary
         * mapping of pages.
         */

        pmap_alloc_specials(&virtual_avail, 1, &csrcp, &csrc_pte);
        pmap_set_pt_cache_mode(kernel_l1pt, (vm_offset_t)csrc_pte);
        pmap_alloc_specials(&virtual_avail, 1, &cdstp, &cdst_pte);
        pmap_set_pt_cache_mode(kernel_l1pt, (vm_offset_t)cdst_pte);
        size = ((vm_max_kernel_address - pmap_curmaxkvaddr) + L1_S_OFFSET) /
            L1_S_SIZE;
        pmap_alloc_specials(&virtual_avail,
            round_page(size * L2_TABLE_SIZE_REAL) / PAGE_SIZE,
            &pmap_kernel_l2ptp_kva, NULL);

        size = (size + (L2_BUCKET_SIZE - 1)) / L2_BUCKET_SIZE;
        pmap_alloc_specials(&virtual_avail,
            round_page(size * sizeof(struct l2_dtable)) / PAGE_SIZE,
            &pmap_kernel_l2dtable_kva, NULL);

        pmap_alloc_specials(&virtual_avail,
            1, (vm_offset_t*)&_tmppt, NULL);
        pmap_alloc_specials(&virtual_avail,
            MAXDUMPPGS, (vm_offset_t *)&crashdumpmap, NULL);
        SLIST_INIT(&l1_list);
        TAILQ_INIT(&l1_lru_list);
        mtx_init(&l1_lru_lock, "l1 list lock", NULL, MTX_DEF);
        pmap_init_l1(l1, kernel_l1pt);
        cpu_dcache_wbinv_all();
        cpu_l2cache_wbinv_all();

        virtual_avail = round_page(virtual_avail);
        virtual_end = vm_max_kernel_address;
        kernel_vm_end = pmap_curmaxkvaddr;
        arm_nocache_startaddr = vm_max_kernel_address;
        mtx_init(&cmtx, "TMP mappings mtx", NULL, MTX_DEF);

        pmap_set_pcb_pagedir(kernel_pmap, thread0.td_pcb);
}

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

/*
 * Release any resources held by the given physical map.
 * Called when a pmap initialized by pmap_pinit is being released.
 * Should only be called if the map contains no valid mappings.
 */
void
pmap_release(pmap_t pmap)
{
        struct pcb *pcb;

        cpu_idcache_wbinv_all();
        cpu_l2cache_wbinv_all();
        cpu_tlb_flushID();
        cpu_cpwait();
        if (vector_page < KERNBASE) {
                struct pcb *curpcb = PCPU_GET(curpcb);
                pcb = thread0.td_pcb;
                if (pmap_is_current(pmap)) {
                        /*
                         * Frob the L1 entry corresponding to the vector
                         * page so that it contains the kernel pmap's domain
                         * number. This will ensure pmap_remove() does not
                         * pull the current vector page out from under us.
                         */
                        critical_enter();
                        *pcb->pcb_pl1vec = pcb->pcb_l1vec;
                        cpu_domains(pcb->pcb_dacr);
                        cpu_setttb(pcb->pcb_pagedir);
                        critical_exit();
                }
                pmap_remove(pmap, vector_page, vector_page + PAGE_SIZE);
                /*
                 * Make sure cpu_switch(), et al, DTRT. This is safe to do
                 * since this process has no remaining mappings of its own.
                 */
                curpcb->pcb_pl1vec = pcb->pcb_pl1vec;
                curpcb->pcb_l1vec = pcb->pcb_l1vec;
                curpcb->pcb_dacr = pcb->pcb_dacr;
                curpcb->pcb_pagedir = pcb->pcb_pagedir;

        }
        pmap_free_l1(pmap);
        PMAP_LOCK_DESTROY(pmap);

        dprintf("pmap_release()\n");
}



/*
 * Helper function for pmap_grow_l2_bucket()
 */
static __inline int
pmap_grow_map(vm_offset_t va, pt_entry_t cache_mode, vm_paddr_t *pap)
{
        struct l2_bucket *l2b;
        pt_entry_t *ptep;
        vm_paddr_t pa;
        struct vm_page *pg;

        pg = vm_page_alloc(NULL, 0, VM_ALLOC_NOOBJ | VM_ALLOC_WIRED);
        if (pg == NULL)
                return (1);
        pa = VM_PAGE_TO_PHYS(pg);

        if (pap)
                *pap = pa;

        l2b = pmap_get_l2_bucket(pmap_kernel(), va);

        ptep = &l2b->l2b_kva[l2pte_index(va)];
        *ptep = L2_S_PROTO | pa | cache_mode;
        pmap_set_prot(ptep, VM_PROT_READ | VM_PROT_WRITE, 0);
        PTE_SYNC(ptep);

        return (0);
}

/*
 * This is the same as pmap_alloc_l2_bucket(), except that it is only
 * used by pmap_growkernel().
 */
static __inline struct l2_bucket *
pmap_grow_l2_bucket(pmap_t pm, vm_offset_t va)
{
        struct l2_dtable *l2;
        struct l2_bucket *l2b;
        struct l1_ttable *l1;
        pd_entry_t *pl1pd;
        u_short l1idx;
        vm_offset_t nva;

        l1idx = L1_IDX(va);

        if ((l2 = pm->pm_l2[L2_IDX(l1idx)]) == NULL) {
                /*
                 * No mapping at this address, as there is
                 * no entry in the L1 table.
                 * Need to allocate a new l2_dtable.
                 */
                nva = pmap_kernel_l2dtable_kva;
                if ((nva & PAGE_MASK) == 0) {
                        /*
                         * Need to allocate a backing page
                         */
                        if (pmap_grow_map(nva, pte_l2_s_cache_mode, NULL))
                                return (NULL);
                }

                l2 = (struct l2_dtable *)nva;
                nva += sizeof(struct l2_dtable);

                if ((nva & PAGE_MASK) < (pmap_kernel_l2dtable_kva &
                    PAGE_MASK)) {
                        /*
                         * The new l2_dtable straddles a page boundary.
                         * Map in another page to cover it.
                         */
                        if (pmap_grow_map(nva, pte_l2_s_cache_mode, NULL))
                                return (NULL);
                }

                pmap_kernel_l2dtable_kva = nva;

                /*
                 * Link it into the parent pmap
                 */
                pm->pm_l2[L2_IDX(l1idx)] = l2;
                memset(l2, 0, sizeof(*l2));
        }

        l2b = &l2->l2_bucket[L2_BUCKET(l1idx)];

        /*
         * Fetch pointer to the L2 page table associated with the address.
         */
        if (l2b->l2b_kva == NULL) {
                pt_entry_t *ptep;

                /*
                 * No L2 page table has been allocated. Chances are, this
                 * is because we just allocated the l2_dtable, above.
                 */
                nva = pmap_kernel_l2ptp_kva;
                ptep = (pt_entry_t *)nva;
                if ((nva & PAGE_MASK) == 0) {
                        /*
                         * Need to allocate a backing page
                         */
                        if (pmap_grow_map(nva, pte_l2_s_cache_mode_pt,
                            &pmap_kernel_l2ptp_phys))
                                return (NULL);
                }
                memset(ptep, 0, L2_TABLE_SIZE_REAL);
                l2->l2_occupancy++;
                l2b->l2b_kva = ptep;
                l2b->l2b_l1idx = l1idx;
                l2b->l2b_phys = pmap_kernel_l2ptp_phys;

                pmap_kernel_l2ptp_kva += L2_TABLE_SIZE_REAL;
                pmap_kernel_l2ptp_phys += L2_TABLE_SIZE_REAL;
        }

        /* Distribute new L1 entry to all other L1s */
        SLIST_FOREACH(l1, &l1_list, l1_link) {
                        pl1pd = &l1->l1_kva[L1_IDX(va)];
                        *pl1pd = l2b->l2b_phys | L1_C_DOM(PMAP_DOMAIN_KERNEL) |
                            L1_C_PROTO;
                        PTE_SYNC(pl1pd);
        }

        return (l2b);
}


/*
 * grow the number of kernel page table entries, if needed
 */
void
pmap_growkernel(vm_offset_t addr)
{
        pmap_t kpm = pmap_kernel();

        if (addr <= pmap_curmaxkvaddr)
                return;         /* we are OK */

        /*
         * whoops!   we need to add kernel PTPs
         */

        /* Map 1MB at a time */
        for (; pmap_curmaxkvaddr < addr; pmap_curmaxkvaddr += L1_S_SIZE)
                pmap_grow_l2_bucket(kpm, pmap_curmaxkvaddr);

        /*
         * flush out the cache, expensive but growkernel will happen so
         * rarely
         */
        cpu_dcache_wbinv_all();
        cpu_l2cache_wbinv_all();
        cpu_tlb_flushD();
        cpu_cpwait();
        kernel_vm_end = pmap_curmaxkvaddr;
}


/*
 * Remove all pages from specified address space
 * this aids process exit speeds.  Also, this code
 * is special cased for current process only, but
 * can have the more generic (and slightly slower)
 * mode enabled.  This is much faster than pmap_remove
 * in the case of running down an entire address space.
 */
void
pmap_remove_pages(pmap_t pmap)
{
        struct pv_entry *pv;
        struct l2_bucket *l2b = NULL;
        vm_page_t m;
        pt_entry_t *pt;
        struct pv_chunk *pc, *npc;
        uint32_t inuse, bitmask;
        int allfree, bit, field, idx;
 
        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pmap);

        TAILQ_FOREACH_SAFE(pc, &pmap->pm_pvchunk, pc_list, npc) {
                allfree = 1;
                for (field = 0; field < _NPCM; field++) {
                        inuse = ~pc->pc_map[field] & pc_freemask[field];
                        while (inuse != 0) {
                                bit = ffs(inuse) - 1;
                                bitmask = 1ul << bit;
                                idx = field * sizeof(inuse) * NBBY + bit;
                                pv = &pc->pc_pventry[idx];
                                inuse &= ~bitmask;
                                if (pv->pv_flags & PVF_WIRED) {
                                        /* Cannot remove wired pages now. */
                                        allfree = 0;
                                        continue;
                                }
                                l2b = pmap_get_l2_bucket(pmap, pv->pv_va);
                                KASSERT(l2b != NULL, ("No L2 bucket in pmap_remove_pages"));
                                pt = &l2b->l2b_kva[l2pte_index(pv->pv_va)];
                                m = PHYS_TO_VM_PAGE(*pt & L2_ADDR_MASK);
                                KASSERT((vm_offset_t)m >= KERNBASE, ("Trying to access non-existent page va %x pte %x", pv->pv_va, *pt));
                                *pt = 0;
                                PTE_SYNC(pt);

                                /* Mark free */
                                PV_STAT(pv_entry_frees++);
                                PV_STAT(pv_entry_spare++);
                                pv_entry_count--;
                                pmap->pm_stats.resident_count--;
                                pc->pc_map[field] |= bitmask;
                                pmap_nuke_pv(m, pmap, pv);
                                pmap_free_l2_bucket(pmap, l2b, 1);
                        }
                }
                if (allfree) {
                        TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
                        pmap_free_pv_chunk(pc);
                }

        }

        rw_wunlock(&pvh_global_lock);
        cpu_tlb_flushID();
        cpu_cpwait();
        PMAP_UNLOCK(pmap);
}


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

#ifdef ARM_HAVE_SUPERSECTIONS
/* Map a super section into the KVA. */

void
pmap_kenter_supersection(vm_offset_t va, uint64_t pa, int flags)
{
        pd_entry_t pd = L1_S_PROTO | L1_S_SUPERSEC | (pa & L1_SUP_FRAME) |
            (((pa >> 32) & 0xf) << 20) | L1_S_PROT(PTE_KERNEL,
            VM_PROT_READ|VM_PROT_WRITE) | L1_S_DOM(PMAP_DOMAIN_KERNEL);
        struct l1_ttable *l1;
        vm_offset_t va0, va_end;

        KASSERT(((va | pa) & L1_SUP_OFFSET) == 0,
            ("Not a valid super section mapping"));
        if (flags & SECTION_CACHE)
                pd |= pte_l1_s_cache_mode;
        else if (flags & SECTION_PT)
                pd |= pte_l1_s_cache_mode_pt;

        va0 = va & L1_SUP_FRAME;
        va_end = va + L1_SUP_SIZE;
        SLIST_FOREACH(l1, &l1_list, l1_link) {
                va = va0;
                for (; va < va_end; va += L1_S_SIZE) {
                        l1->l1_kva[L1_IDX(va)] = pd;
                        PTE_SYNC(&l1->l1_kva[L1_IDX(va)]);
                }
        }
}
#endif

/* Map a section into the KVA. */

void
pmap_kenter_section(vm_offset_t va, vm_offset_t pa, int flags)
{
        pd_entry_t pd = L1_S_PROTO | pa | L1_S_PROT(PTE_KERNEL,
            VM_PROT_READ|VM_PROT_WRITE) | L1_S_DOM(PMAP_DOMAIN_KERNEL);
        struct l1_ttable *l1;

        KASSERT(((va | pa) & L1_S_OFFSET) == 0,
            ("Not a valid section mapping"));
        if (flags & SECTION_CACHE)
                pd |= pte_l1_s_cache_mode;
        else if (flags & SECTION_PT)
                pd |= pte_l1_s_cache_mode_pt;

        SLIST_FOREACH(l1, &l1_list, l1_link) {
                l1->l1_kva[L1_IDX(va)] = pd;
                PTE_SYNC(&l1->l1_kva[L1_IDX(va)]);
        }
}

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

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

/*
 * add a wired page to the kva
 * note that in order for the mapping to take effect -- you
 * should do a invltlb after doing the pmap_kenter...
 */
static PMAP_INLINE void
pmap_kenter_internal(vm_offset_t va, vm_offset_t pa, int flags)
{
        struct l2_bucket *l2b;
        pt_entry_t *pte;
        pt_entry_t opte;

        PDEBUG(1, printf("pmap_kenter: va = %08x, pa = %08x\n",
            (uint32_t) va, (uint32_t) pa));


        l2b = pmap_get_l2_bucket(pmap_kernel(), va);
        if (l2b == NULL)
                l2b = pmap_grow_l2_bucket(pmap_kernel(), va);
        KASSERT(l2b != NULL, ("No L2 Bucket"));

        pte = &l2b->l2b_kva[l2pte_index(va)];
        opte = *pte;
        if (l2pte_valid(opte)) {
                cpu_tlb_flushD_SE(va);
                cpu_cpwait();
        } else {
                if (opte == 0)
                        l2b->l2b_occupancy++;
        }

        if (flags & KENTER_CACHE) {
                *pte = L2_S_PROTO | pa | pte_l2_s_cache_mode;
                pmap_set_prot(pte, VM_PROT_READ | VM_PROT_WRITE,
                    flags & KENTER_USER);
        } else {
                *pte = L2_S_PROTO | pa;
                pmap_set_prot(pte, VM_PROT_READ|VM_PROT_WRITE|VM_PROT_EXECUTE,
                    0);
        }

        PDEBUG(1, printf("pmap_kenter: pte = %08x, opte = %08x, npte = %08x\n",
            (uint32_t) pte, opte, *pte));
        PTE_SYNC(pte);
        cpu_cpwait();
}

void
pmap_kenter(vm_offset_t va, vm_paddr_t pa)
{
        pmap_kenter_internal(va, pa, KENTER_CACHE);
}

void
pmap_kenter_nocache(vm_offset_t va, vm_paddr_t pa)
{

        pmap_kenter_internal(va, pa, 0);
}

void
pmap_kenter_user(vm_offset_t va, vm_paddr_t pa)
{

        pmap_kenter_internal(va, pa, KENTER_CACHE|KENTER_USER);
        /*
         * Call pmap_fault_fixup now, to make sure we'll have no exception
         * at the first use of the new address, or bad things will happen,
         * as we use one of these addresses in the exception handlers.
         */
        pmap_fault_fixup(pmap_kernel(), va, VM_PROT_READ|VM_PROT_WRITE, 1);
}

vm_paddr_t
pmap_kextract(vm_offset_t va)
{

        return (pmap_extract_locked(kernel_pmap, va));
}

/*
 * remove a page from the kernel pagetables
 */
void
pmap_kremove(vm_offset_t va)
{
        struct l2_bucket *l2b;
        pt_entry_t *pte, opte;

        l2b = pmap_get_l2_bucket(pmap_kernel(), va);
        if (!l2b)
                return;
        KASSERT(l2b != NULL, ("No L2 Bucket"));
        pte = &l2b->l2b_kva[l2pte_index(va)];
        opte = *pte;
        if (l2pte_valid(opte)) {
                va = va & ~PAGE_MASK;
                cpu_tlb_flushD_SE(va);
                cpu_cpwait();
                *pte = 0;
                PTE_SYNC(pte);
        }
}


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

        PDEBUG(1, printf("pmap_map: virt = %08x, start = %08x, end = %08x, "
            "prot = %d\n", (uint32_t) *virt, (uint32_t) start, (uint32_t) end,
            prot));

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

/*
 * Add a list of wired pages to the kva
 * this routine is only used for temporary
 * kernel mappings that do not need to have
 * page modification or references recorded.
 * Note that old mappings are simply written
 * over.  The page *must* be wired.
 */
void
pmap_qenter(vm_offset_t va, vm_page_t *m, int count)
{
        int i;

        for (i = 0; i < count; i++) {
                pmap_kenter_internal(va, VM_PAGE_TO_PHYS(m[i]),
                    KENTER_CACHE);
                va += PAGE_SIZE;
        }
}


/*
 * this routine jerks page mappings from the
 * kernel -- it is meant only for temporary mappings.
 */
void
pmap_qremove(vm_offset_t va, int count)
{
        int i;

        for (i = 0; i < count; i++) {
                if (vtophys(va))
                        pmap_kremove(va);

                va += PAGE_SIZE;
        }
}


/*
 * pmap_object_init_pt 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.
 */
void
pmap_object_init_pt(pmap_t pmap, vm_offset_t addr, vm_object_t object,
    vm_pindex_t pindex, vm_size_t size)
{

        VM_OBJECT_ASSERT_WLOCKED(object);
        KASSERT(object->type == OBJT_DEVICE || object->type == OBJT_SG,
            ("pmap_object_init_pt: non-device object"));
}


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

        if (!pmap_get_pde_pte(pmap, addr, &pde, &pte))
                return (FALSE);
        KASSERT(pte != NULL, ("Valid mapping but no pte ?"));
        if (*pte == 0)
                return (TRUE);
        return (FALSE);
}

/*
 * Fetch pointers to the PDE/PTE for the given pmap/VA pair.
 * Returns TRUE if the mapping exists, else FALSE.
 *
 * NOTE: This function is only used by a couple of arm-specific modules.
 * It is not safe to take any pmap locks here, since we could be right
 * in the middle of debugging the pmap anyway...
 *
 * It is possible for this routine to return FALSE even though a valid
 * mapping does exist. This is because we don't lock, so the metadata
 * state may be inconsistent.
 *
 * NOTE: We can return a NULL *ptp in the case where the L1 pde is
 * a "section" mapping.
 */
boolean_t
pmap_get_pde_pte(pmap_t pm, vm_offset_t va, pd_entry_t **pdp, pt_entry_t **ptp)
{
        struct l2_dtable *l2;
        pd_entry_t *pl1pd, l1pd;
        pt_entry_t *ptep;
        u_short l1idx;

        if (pm->pm_l1 == NULL)
                return (FALSE);

        l1idx = L1_IDX(va);
        *pdp = pl1pd = &pm->pm_l1->l1_kva[l1idx];
        l1pd = *pl1pd;

        if (l1pte_section_p(l1pd)) {
                *ptp = NULL;
                return (TRUE);
        }

        if (pm->pm_l2 == NULL)
                return (FALSE);

        l2 = pm->pm_l2[L2_IDX(l1idx)];

        if (l2 == NULL ||
            (ptep = l2->l2_bucket[L2_BUCKET(l1idx)].l2b_kva) == NULL) {
                return (FALSE);
        }

        *ptp = &ptep[l2pte_index(va)];
        return (TRUE);
}

/*
 *      Routine:        pmap_remove_all
 *      Function:
 *              Removes this physical page from
 *              all physical maps in which it resides.
 *              Reflects back modify bits to the pager.
 *
 *      Notes:
 *              Original versions of this routine were very
 *              inefficient because they iteratively called
 *              pmap_remove (slow...)
 */
void
pmap_remove_all(vm_page_t m)
{
        pv_entry_t pv;
        pmap_t pmap;
        pt_entry_t *ptep;
        struct l2_bucket *l2b;
        boolean_t flush = FALSE;
        pmap_t curpm;
        int flags = 0;

        KASSERT((m->flags & PG_FICTITIOUS) == 0,
            ("pmap_remove_all: page %p is fictitious", m));

        if (TAILQ_EMPTY(&m->md.pv_list))
                return;
        rw_wlock(&pvh_global_lock);
        curpm = vmspace_pmap(curproc->p_vmspace);
        while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
                pmap = PV_PMAP(pv);
                if (flush == FALSE && (pmap == curpm ||
                    pmap == pmap_kernel()))
                        flush = TRUE;

                PMAP_LOCK(pmap);
                l2b = pmap_get_l2_bucket(pmap, pv->pv_va);
                KASSERT(l2b != NULL, ("No l2 bucket"));
                ptep = &l2b->l2b_kva[l2pte_index(pv->pv_va)];
                if (L2_S_WRITABLE(*ptep))
                        vm_page_dirty(m);
                *ptep = 0;
                if (pmap_is_current(pmap))
                        PTE_SYNC(ptep);
                pmap_free_l2_bucket(pmap, l2b, 1);
                pmap->pm_stats.resident_count--;
                flags |= pv->pv_flags;
                pmap_nuke_pv(m, pmap, pv);
                pmap_free_pv_entry(pmap, pv);
                PMAP_UNLOCK(pmap);
        }
        m->md.pvh_attrs &= ~(PVF_MOD | PVF_REF);

        if (flush) {
                if (PV_BEEN_EXECD(flags))
                        cpu_tlb_flushID();
                else
                        cpu_tlb_flushD();
        }
        vm_page_aflag_clear(m, PGA_WRITEABLE);
        rw_wunlock(&pvh_global_lock);
}

int
pmap_change_attr(vm_offset_t sva, vm_size_t len, int mode)
{
        vm_offset_t base, offset, tmpva;
        vm_size_t size;
        struct l2_bucket *l2b;
        pt_entry_t *ptep, pte;
        vm_offset_t next_bucket;

        PMAP_LOCK(kernel_pmap);

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

#ifdef checkit
        /*
         * Only supported on kernel virtual addresses, including the direct
         * map but excluding the recursive map.
         */
        if (base < DMAP_MIN_ADDRESS) {
                PMAP_UNLOCK(kernel_pmap);
                return (EINVAL);
        }
#endif
        for (tmpva = base; tmpva < base + size; ) {
                next_bucket = L2_NEXT_BUCKET(tmpva);
                if (next_bucket > base + size)
                        next_bucket = base + size;

                l2b = pmap_get_l2_bucket(kernel_pmap, tmpva);
                if (l2b == NULL) {
                        tmpva = next_bucket;
                        continue;
                }

                ptep = &l2b->l2b_kva[l2pte_index(tmpva)];

                if (*ptep == 0) {
                        PMAP_UNLOCK(kernel_pmap);
                        return(EINVAL);
                }

                pte = *ptep &~ L2_S_CACHE_MASK;
                cpu_idcache_wbinv_range(tmpva, PAGE_SIZE);
                pmap_l2cache_wbinv_range(tmpva, pte & L2_S_FRAME, PAGE_SIZE);
                *ptep = pte;
                cpu_tlb_flushID_SE(tmpva);

                dprintf("%s: for va:%x ptep:%x pte:%x\n",
                    __func__, tmpva, (uint32_t)ptep, pte);
                tmpva += PAGE_SIZE;
        }

        PMAP_UNLOCK(kernel_pmap);

        return (0);
}

/*
 *      Set the physical protection on the
 *      specified range of this map as requested.
 */
void
pmap_protect(pmap_t pm, vm_offset_t sva, vm_offset_t eva, vm_prot_t prot)
{
        struct l2_bucket *l2b;
        pt_entry_t *ptep, pte;
        vm_offset_t next_bucket;
        u_int flags;
        int flush;

        if ((prot & VM_PROT_READ) == 0) {
                pmap_remove(pm, sva, eva);
                return;
        }

        if (prot & VM_PROT_WRITE) {
                /*
                 * If this is a read->write transition, just ignore it and let
                 * vm_fault() take care of it later.
                 */
                return;
        }

        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pm);

        /*
         * OK, at this point, we know we're doing write-protect operation.
         * If the pmap is active, write-back the range.
         */

        flush = ((eva - sva) >= (PAGE_SIZE * 4)) ? 0 : -1;
        flags = 0;

        while (sva < eva) {
                next_bucket = L2_NEXT_BUCKET(sva);
                if (next_bucket > eva)
                        next_bucket = eva;

                l2b = pmap_get_l2_bucket(pm, sva);
                if (l2b == NULL) {
                        sva = next_bucket;
                        continue;
                }

                ptep = &l2b->l2b_kva[l2pte_index(sva)];

                while (sva < next_bucket) {
                        if ((pte = *ptep) != 0 && L2_S_WRITABLE(pte)) {
                                struct vm_page *pg;
                                u_int f;

                                pg = PHYS_TO_VM_PAGE(l2pte_pa(pte));
                                pmap_set_prot(ptep, prot, !(pm == pmap_kernel()));
                                PTE_SYNC(ptep);

                                f = pmap_modify_pv(pg, pm, sva,
                                    PVF_WRITE, 0);
                                if (f & PVF_WRITE)
                                        vm_page_dirty(pg);

                                if (flush >= 0) {
                                        flush++;
                                        flags |= f;
                                } else
                                if (PV_BEEN_EXECD(f))
                                        cpu_tlb_flushID_SE(sva);
                                else
                                if (PV_BEEN_REFD(f))
                                        cpu_tlb_flushD_SE(sva);
                        }

                        sva += PAGE_SIZE;
                        ptep++;
                }
        }


        if (flush) {
                if (PV_BEEN_EXECD(flags))
                        cpu_tlb_flushID();
                else
                if (PV_BEEN_REFD(flags))
                        cpu_tlb_flushD();
        }
        rw_wunlock(&pvh_global_lock);

        PMAP_UNLOCK(pm);
}


/*
 *      Insert the given physical page (p) at
 *      the specified virtual address (v) in the
 *      target physical map with the protection requested.
 *
 *      If specified, the page will be wired down, meaning
 *      that the related pte can not be reclaimed.
 *
 *      NB:  This is the only routine which MAY NOT lazy-evaluate
 *      or lose information.  That is, this routine must actually
 *      insert this page into the given map NOW.
 */

void
pmap_enter(pmap_t pmap, vm_offset_t va, vm_prot_t access, vm_page_t m,
    vm_prot_t prot, boolean_t wired)
{

        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pmap);
        pmap_enter_locked(pmap, va, m, prot, wired, M_WAITOK);
        PMAP_UNLOCK(pmap);
        rw_wunlock(&pvh_global_lock);
}

/*
 *      The pvh global and pmap locks must be held.
 */
static void
pmap_enter_locked(pmap_t pmap, vm_offset_t va, vm_page_t m, vm_prot_t prot,
    boolean_t wired, int flags)
{
        struct l2_bucket *l2b = NULL;
        struct vm_page *opg;
        struct pv_entry *pve = NULL;
        pt_entry_t *ptep, npte, opte;
        u_int nflags;
        u_int oflags;
        vm_paddr_t pa;
        u_char user;

        PMAP_ASSERT_LOCKED(pmap);
        rw_assert(&pvh_global_lock, RA_WLOCKED);
        if (va == vector_page) {
                pa = systempage.pv_pa;
                m = NULL;
        } else {
                KASSERT((m->oflags & (VPO_UNMANAGED | VPO_BUSY)) != 0 ||
                    (flags & M_NOWAIT) != 0,
                    ("pmap_enter_locked: page %p is not busy", m));
                pa = VM_PAGE_TO_PHYS(m);
        }

        user = 0;
        /*
         * Make sure userland mappings get the right permissions
         */
        if (pmap != pmap_kernel() && va != vector_page)
                user = 1;

        nflags = 0;

        if (prot & VM_PROT_WRITE)
                nflags |= PVF_WRITE;
        if (prot & VM_PROT_EXECUTE)
                nflags |= PVF_EXEC;
        if (wired)
                nflags |= PVF_WIRED;

        PDEBUG(1, printf("pmap_enter: pmap = %08x, va = %08x, m = %08x, prot = %x, "
            "wired = %x\n", (uint32_t) pmap, va, (uint32_t) m, prot, wired));

        if (pmap == pmap_kernel()) {
                l2b = pmap_get_l2_bucket(pmap, va);
                if (l2b == NULL)
                        l2b = pmap_grow_l2_bucket(pmap, va);
        } else {
do_l2b_alloc:
                l2b = pmap_alloc_l2_bucket(pmap, va);
                if (l2b == NULL) {
                        if (flags & M_WAITOK) {
                                PMAP_UNLOCK(pmap);
                                rw_wunlock(&pvh_global_lock);
                                VM_WAIT;
                                rw_wlock(&pvh_global_lock);
                                PMAP_LOCK(pmap);
                                goto do_l2b_alloc;
                        }
                        return;
                }
        }

        ptep = &l2b->l2b_kva[l2pte_index(va)];

        opte = *ptep;
        npte = pa;
        oflags = 0;
        if (opte) {
                /*
                 * There is already a mapping at this address.
                 * If the physical address is different, lookup the
                 * vm_page.
                 */
                if (l2pte_pa(opte) != pa)
                        opg = PHYS_TO_VM_PAGE(l2pte_pa(opte));
                else
                        opg = m;
        } else
                opg = NULL;

        if ((prot & (VM_PROT_ALL)) ||
            (!m || m->md.pvh_attrs & PVF_REF)) {
                /*
                 * - The access type indicates that we don't need
                 *   to do referenced emulation.
                 * OR
                 * - The physical page has already been referenced
                 *   so no need to re-do referenced emulation here.
                 */
                npte |= L2_S_PROTO;
#ifdef SMP
                npte |= L2_SHARED;
#endif

                nflags |= PVF_REF;

                if (m && ((prot & VM_PROT_WRITE) != 0 ||
                    (m->md.pvh_attrs & PVF_MOD))) {
                        /*
                         * This is a writable mapping, and the
                         * page's mod state indicates it has
                         * already been modified. Make it
                         * writable from the outset.
                         */
                        nflags |= PVF_MOD;
                        if (!(m->md.pvh_attrs & PVF_MOD))
                                vm_page_dirty(m);
                }
                if (m && opte)
                        vm_page_aflag_set(m, PGA_REFERENCED);
        } else {
                /*
                 * Need to do page referenced emulation.
                 */
                npte &= ~L2_TYPE_MASK;
                npte |= L2_TYPE_INV;
        }

        npte |= L2_APX;
        npte |= L2_S_PROT_R;
        if (user)
                npte |= L2_S_PROT_U;

        if (prot & VM_PROT_WRITE) {
                npte &= ~(L2_APX);

                if (m != NULL &&
                    (m->oflags & VPO_UNMANAGED) == 0)
                        vm_page_aflag_set(m, PGA_WRITEABLE);
        } else if (user)
                npte &= ~(L2_S_PROT_R);

        if (!(prot & VM_PROT_EXECUTE) && m)
                npte |= L2_XN;

        if (m->md.pv_memattr != VM_MEMATTR_UNCACHEABLE)
                npte |= pte_l2_s_cache_mode;

        if (m && m == opg) {
                /*
                 * We're changing the attrs of an existing mapping.
                 */
                oflags = pmap_modify_pv(m, pmap, va,
                    PVF_WRITE | PVF_EXEC | PVF_WIRED |
                    PVF_MOD | PVF_REF, nflags);
        } else {
                /*
                 * New mapping, or changing the backing page
                 * of an existing mapping.
                 */
                if (opg) {
                        /*
                         * Replacing an existing mapping with a new one.
                         * It is part of our managed memory so we
                         * must remove it from the PV list
                         */
                        if ((pve = pmap_remove_pv(opg, pmap, va))) {
                            oflags = pve->pv_flags;

                            if (m && ((m->oflags & VPO_UNMANAGED)))
                                pmap_free_pv_entry(pmap, pve);
                        }
                }

                if ((m && !(m->oflags & VPO_UNMANAGED))) {
                        if ((!pve) && (pve = pmap_get_pv_entry(pmap, FALSE)) == NULL)
                                panic("pmap_enter: no pv entries");

                        KASSERT(va < kmi.clean_sva || va >= kmi.clean_eva,
                        ("pmap_enter: managed mapping within the clean submap"));
                        KASSERT(pve != NULL, ("No pv"));
                        pmap_enter_pv(m, pve, pmap, va, nflags);
                }
        }

        /*
         * Keep the stats up to date
         */
        if (opte == 0) {
                l2b->l2b_occupancy++;
                pmap->pm_stats.resident_count++;
        }

        CTR5(KTR_PMAP,"enter: pmap:%p va:%x prot:%x pte:%x->%x",
            pmap, va, prot, opte, npte);
        /*
         * If this is just a wiring change, the two PTEs will be
         * identical, so there's no need to update the page table.
         */
        if (npte != opte) {
                boolean_t is_cached = pmap_is_current(pmap);

                *ptep = npte;
                PTE_SYNC(ptep);
                if (is_cached) {
                        /*
                         * We only need to frob the cache/tlb if this pmap
                         * is current
                         */
                        if (L1_IDX(va) != L1_IDX(vector_page) &&
                            l2pte_valid(npte)) {
                                /*
                                 * This mapping is likely to be accessed as
                                 * soon as we return to userland. Fix up the
                                 * L1 entry to avoid taking another
                                 * page/domain fault.
                                 */
                                pd_entry_t *pl1pd, l1pd;

                                pl1pd = &pmap->pm_l1->l1_kva[L1_IDX(va)];
                                l1pd = l2b->l2b_phys | L1_C_DOM(pmap->pm_domain) |
                                    L1_C_PROTO;
                                if (*pl1pd != l1pd) {
                                        *pl1pd = l1pd;
                                        PTE_SYNC(pl1pd);
                                }
                        }
                }

                if (PV_BEEN_EXECD(oflags))
                        cpu_tlb_flushID_SE(va);
                else if (PV_BEEN_REFD(oflags))
                        cpu_tlb_flushD_SE(va);
        }

        if ((pmap != pmap_kernel()) && (pmap == &curproc->p_vmspace->vm_pmap))
                cpu_icache_sync_range(va, PAGE_SIZE);
}

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

        VM_OBJECT_ASSERT_LOCKED(m_start->object);

        psize = atop(end - start);
        m = m_start;
        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pmap);
        while (m != NULL && (diff = m->pindex - m_start->pindex) < psize) {
                pmap_enter_locked(pmap, start + ptoa(diff), m, prot &
                    (VM_PROT_READ | VM_PROT_EXECUTE), FALSE, M_NOWAIT);
                m = TAILQ_NEXT(m, listq);
        }
        PMAP_UNLOCK(pmap);
        rw_wunlock(&pvh_global_lock);
}

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

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

        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pmap);
        pmap_enter_locked(pmap, va, m, prot & (VM_PROT_READ | VM_PROT_EXECUTE),
            FALSE, M_NOWAIT);
        PMAP_UNLOCK(pmap);
        rw_wunlock(&pvh_global_lock);
}

/*
 *      Routine:        pmap_change_wiring
 *      Function:       Change the wiring attribute for a map/virtual-address
 *                      pair.
 *      In/out conditions:
 *                      The mapping must already exist in the pmap.
 */
void
pmap_change_wiring(pmap_t pmap, vm_offset_t va, boolean_t wired)
{
        struct l2_bucket *l2b;
        pt_entry_t *ptep, pte;
        vm_page_t pg;

        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pmap);
        l2b = pmap_get_l2_bucket(pmap, va);
        KASSERT(l2b, ("No l2b bucket in pmap_change_wiring"));
        ptep = &l2b->l2b_kva[l2pte_index(va)];
        pte = *ptep;
        pg = PHYS_TO_VM_PAGE(l2pte_pa(pte));
        if (pg)
                pmap_modify_pv(pg, pmap, va, PVF_WIRED, wired);
        rw_wunlock(&pvh_global_lock);
        PMAP_UNLOCK(pmap);
}


/*
 *      Copy the range specified by src_addr/len
 *      from the source map to the range dst_addr/len
 *      in the destination map.
 *
 *      This routine is only advisory and need not do anything.
 */
void
pmap_copy(pmap_t dst_pmap, pmap_t src_pmap, vm_offset_t dst_addr,
    vm_size_t len, vm_offset_t src_addr)
{
}


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

        PMAP_LOCK(pmap);
        pa = pmap_extract_locked(pmap, va);
        PMAP_UNLOCK(pmap);
        return (pa);
}

static vm_paddr_t
pmap_extract_locked(pmap_t pmap, vm_offset_t va)
{
        struct l2_dtable *l2;
        pd_entry_t l1pd;
        pt_entry_t *ptep, pte;
        vm_paddr_t pa;
        u_int l1idx;

        if (pmap != kernel_pmap)
                PMAP_ASSERT_LOCKED(pmap);
        l1idx = L1_IDX(va);
        l1pd = pmap->pm_l1->l1_kva[l1idx];
        if (l1pte_section_p(l1pd)) {
                /*
                 * These should only happen for the kernel pmap.
                 */
                KASSERT(pmap == kernel_pmap, ("unexpected section"));
                /* XXX: what to do about the bits > 32 ? */
                if (l1pd & L1_S_SUPERSEC)
                        pa = (l1pd & L1_SUP_FRAME) | (va & L1_SUP_OFFSET);
                else
                        pa = (l1pd & L1_S_FRAME) | (va & L1_S_OFFSET);
        } else {
                /*
                 * Note that we can't rely on the validity of the L1
                 * descriptor as an indication that a mapping exists.
                 * We have to look it up in the L2 dtable.
                 */
                l2 = pmap->pm_l2[L2_IDX(l1idx)];
                if (l2 == NULL ||
                    (ptep = l2->l2_bucket[L2_BUCKET(l1idx)].l2b_kva) == NULL)
                        return (0);
                pte = ptep[l2pte_index(va)];
                if (pte == 0)
                        return (0);
                switch (pte & L2_TYPE_MASK) {
                case L2_TYPE_L:
                        pa = (pte & L2_L_FRAME) | (va & L2_L_OFFSET);
                        break;
                default:
                        pa = (pte & L2_S_FRAME) | (va & L2_S_OFFSET);
                        break;
                }
        }
        return (pa);
}

/*
 * Atomically extract and hold the physical page with the given
 * pmap and virtual address pair if that mapping permits the given
 * protection.
 *
 */
vm_page_t
pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
{
        struct l2_dtable *l2;
        pd_entry_t l1pd;
        pt_entry_t *ptep, pte;
        vm_paddr_t pa, paddr;
        vm_page_t m = NULL;
        u_int l1idx;
        l1idx = L1_IDX(va);
        paddr = 0;

        PMAP_LOCK(pmap);
retry:
        l1pd = pmap->pm_l1->l1_kva[l1idx];
        if (l1pte_section_p(l1pd)) {
                /*
                 * These should only happen for pmap_kernel()
                 */
                KASSERT(pmap == pmap_kernel(), ("huh"));
                /* XXX: what to do about the bits > 32 ? */
                if (l1pd & L1_S_SUPERSEC)
                        pa = (l1pd & L1_SUP_FRAME) | (va & L1_SUP_OFFSET);
                else
                        pa = (l1pd & L1_S_FRAME) | (va & L1_S_OFFSET);
                if (vm_page_pa_tryrelock(pmap, pa & PG_FRAME, &paddr))
                        goto retry;
                if (L1_S_WRITABLE(l1pd) || (prot & VM_PROT_WRITE) == 0) {
                        m = PHYS_TO_VM_PAGE(pa);
                        vm_page_hold(m);
                }
        } else {
                /*
                 * Note that we can't rely on the validity of the L1
                 * descriptor as an indication that a mapping exists.
                 * We have to look it up in the L2 dtable.
                 */
                l2 = pmap->pm_l2[L2_IDX(l1idx)];

                if (l2 == NULL ||
                    (ptep = l2->l2_bucket[L2_BUCKET(l1idx)].l2b_kva) == NULL) {
                        PMAP_UNLOCK(pmap);
                        return (NULL);
                }

                ptep = &ptep[l2pte_index(va)];
                pte = *ptep;

                if (pte == 0) {
                        PMAP_UNLOCK(pmap);
                        return (NULL);
                } else if ((prot & VM_PROT_WRITE) && (pte & L2_APX)) {
                        PMAP_UNLOCK(pmap);
                        return (NULL);
                } else {
                        switch (pte & L2_TYPE_MASK) {
                        case L2_TYPE_L:
                                panic("extract and hold section mapping");
                                break;
                        default:
                                pa = (pte & L2_S_FRAME) | (va & L2_S_OFFSET);
                                break;
                        }
                        if (vm_page_pa_tryrelock(pmap, pa & PG_FRAME, &paddr))
                                goto retry;
                        m = PHYS_TO_VM_PAGE(pa);
                        vm_page_hold(m);
                }

        }

        PMAP_UNLOCK(pmap);
        PA_UNLOCK_COND(paddr);
        return (m);
}

/*
 * Initialize a preallocated and zeroed pmap structure,
 * such as one in a vmspace structure.
 */

int
pmap_pinit(pmap_t pmap)
{
        PDEBUG(1, printf("pmap_pinit: pmap = %08x\n", (uint32_t) pmap));

        PMAP_LOCK_INIT(pmap);
        pmap_alloc_l1(pmap);
        bzero(pmap->pm_l2, sizeof(pmap->pm_l2));

        CPU_ZERO(&pmap->pm_active);

        TAILQ_INIT(&pmap->pm_pvchunk);
        bzero(&pmap->pm_stats, sizeof pmap->pm_stats);
        pmap->pm_stats.resident_count = 1;
        if (vector_page < KERNBASE) {
                pmap_enter(pmap, vector_page,
                    VM_PROT_READ, PHYS_TO_VM_PAGE(systempage.pv_pa),
                    VM_PROT_READ, 1);
        }
        return (1);
}


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

/*
 * We are in a serious low memory condition.  Resort to
 * drastic measures to free some pages so we can allocate
 * another pv entry chunk.
 */
static vm_page_t
pmap_pv_reclaim(pmap_t locked_pmap)
{
        struct pch newtail;
        struct pv_chunk *pc;
        struct l2_bucket *l2b = NULL;
        pmap_t pmap;
        pt_entry_t *pt;
        pv_entry_t pv;
        vm_offset_t va;
        vm_page_t free, m, m_pc;
        uint32_t inuse;
        int bit, field, freed, idx;

        PMAP_ASSERT_LOCKED(locked_pmap);
        pmap = NULL;
        free = m_pc = NULL;
        TAILQ_INIT(&newtail);
        while ((pc = TAILQ_FIRST(&pv_chunks)) != NULL && (pv_vafree == 0 ||
            free == NULL)) {
                TAILQ_REMOVE(&pv_chunks, pc, pc_lru);
                if (pmap != pc->pc_pmap) {
                        if (pmap != NULL) {
                                cpu_tlb_flushID();
                                cpu_cpwait();
                                if (pmap != locked_pmap)
                                        PMAP_UNLOCK(pmap);
                        }
                        pmap = pc->pc_pmap;
                        /* Avoid deadlock and lock recursion. */
                        if (pmap > locked_pmap)
                                PMAP_LOCK(pmap);
                        else if (pmap != locked_pmap && !PMAP_TRYLOCK(pmap)) {
                                pmap = NULL;
                                TAILQ_INSERT_TAIL(&newtail, pc, pc_lru);
                                continue;
                        }
                }

                /*
                 * Destroy every non-wired, 4 KB page mapping in the chunk.
                 */
                freed = 0;
                for (field = 0; field < _NPCM; field++) {
                        for (inuse = ~pc->pc_map[field] & pc_freemask[field];
                            inuse != 0; inuse &= ~(1UL << bit)) {
                                bit = ffs(inuse) - 1;
                                idx = field * sizeof(inuse) * NBBY + bit;
                                pv = &pc->pc_pventry[idx];
                                if (pv->pv_flags & PVF_WIRED)
                                        continue;

                                va = pv->pv_va;
                                l2b = pmap_get_l2_bucket(pmap, va);
                                KASSERT(l2b != NULL, ("No l2 bucket"));
                                pt = &l2b->l2b_kva[l2pte_index(va)];
                                m = PHYS_TO_VM_PAGE(l2pte_pa(*pt));
                                KASSERT((vm_offset_t)m >= KERNBASE,
                                    ("Trying to access non-existent page "
                                     "va %x pte %x in %s", va, *pt));
                                *pt = 0;
                                PTE_SYNC(pt);
                                pmap_nuke_pv(m, pmap, pv);
                                pc->pc_map[field] |= 1UL << bit;
                                freed++;
                        }
                }

                if (freed == 0) {
                        TAILQ_INSERT_TAIL(&newtail, pc, pc_lru);
                        continue;
                }
                /* Every freed mapping is for a 4 KB page. */
                pmap->pm_stats.resident_count -= freed;
                PV_STAT(pv_entry_frees += freed);
                PV_STAT(pv_entry_spare += freed);
                pv_entry_count -= freed;
                TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
                for (field = 0; field < _NPCM; field++)
                        if (pc->pc_map[field] != pc_freemask[field]) {
                                TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc,
                                    pc_list);
                                TAILQ_INSERT_TAIL(&newtail, pc, pc_lru);

                                /*
                                 * One freed pv entry in locked_pmap is
                                 * sufficient.
                                 */
                                if (pmap == locked_pmap)
                                        goto out;
                                break;
                        }
                if (field == _NPCM) {
                        PV_STAT(pv_entry_spare -= _NPCPV);
                        PV_STAT(pc_chunk_count--);
                        PV_STAT(pc_chunk_frees++);
                        /* Entire chunk is free; return it. */
                        m_pc = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)pc));
                        pmap_qremove((vm_offset_t)pc, 1);
                        pmap_ptelist_free(&pv_vafree, (vm_offset_t)pc);
                        break;
                }
        }
out:
        TAILQ_CONCAT(&pv_chunks, &newtail, pc_lru);
        if (pmap != NULL) {
                cpu_tlb_flushID();
                cpu_cpwait();
                if (pmap != locked_pmap)
                        PMAP_UNLOCK(pmap);
        }
        return (m_pc);
}

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

        rw_assert(&pvh_global_lock, RA_WLOCKED);
        PMAP_ASSERT_LOCKED(pmap);
        PV_STAT(pv_entry_frees++);
        PV_STAT(pv_entry_spare++);
        pv_entry_count--;
        pc = pv_to_chunk(pv);
        idx = pv - &pc->pc_pventry[0];
        field = idx / (sizeof(u_long) * NBBY);
        bit = idx % (sizeof(u_long) * NBBY);
        pc->pc_map[field] |= 1ul << bit;
        for (idx = 0; idx < _NPCM; idx++)
                if (pc->pc_map[idx] != pc_freemask[idx]) {
                        /*
                         * 98% of the time, pc is already at the head of the
                         * list.  If it isn't already, move it to the head.
                         */
                        if (__predict_false(TAILQ_FIRST(&pmap->pm_pvchunk) !=
                            pc)) {
                                TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
                                TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc,
                                    pc_list);
                        }
                        return;
                }
        TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
        pmap_free_pv_chunk(pc);
}

static void
pmap_free_pv_chunk(struct pv_chunk *pc)
{
        vm_page_t m;

        TAILQ_REMOVE(&pv_chunks, pc, pc_lru);
        PV_STAT(pv_entry_spare -= _NPCPV);
        PV_STAT(pc_chunk_count--);
        PV_STAT(pc_chunk_frees++);
        /* entire chunk is free, return it */
        m = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)pc));
        pmap_qremove((vm_offset_t)pc, 1);
        vm_page_unwire(m, 0);
        vm_page_free(m);
        pmap_ptelist_free(&pv_vafree, (vm_offset_t)pc);

}

static pv_entry_t
pmap_get_pv_entry(pmap_t pmap, boolean_t try)
{
        static const struct timeval printinterval = { 60, 0 };
        static struct timeval lastprint;
        struct pv_chunk *pc;
        pv_entry_t pv;
        vm_page_t m;
        int bit, field, idx;

        rw_assert(&pvh_global_lock, RA_WLOCKED);
        PMAP_ASSERT_LOCKED(pmap);
        PV_STAT(pv_entry_allocs++);
        pv_entry_count++;

        if (pv_entry_count > pv_entry_high_water)
                if (ratecheck(&lastprint, &printinterval))
                        printf("%s: Approaching the limit on PV entries.\n",
                            __func__);
retry:
        pc = TAILQ_FIRST(&pmap->pm_pvchunk);
        if (pc != NULL) {
                for (field = 0; field < _NPCM; field++) {
                        if (pc->pc_map[field]) {
                                bit = ffs(pc->pc_map[field]) - 1;
                                break;
                        }
                }
                if (field < _NPCM) {
                        idx = field * sizeof(pc->pc_map[field]) * NBBY + bit;
                        pv = &pc->pc_pventry[idx];
                        pc->pc_map[field] &= ~(1ul << bit);
                        /* If this was the last item, move it to tail */
                        for (field = 0; field < _NPCM; field++)
                                if (pc->pc_map[field] != 0) {
                                        PV_STAT(pv_entry_spare--);
                                        return (pv);    /* not full, return */
                                }
                        TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
                        TAILQ_INSERT_TAIL(&pmap->pm_pvchunk, pc, pc_list);
                        PV_STAT(pv_entry_spare--);
                        return (pv);
                }
        }
        /*
         * Access to the ptelist "pv_vafree" is synchronized by the pvh
         * global lock.  If "pv_vafree" is currently non-empty, it will
         * remain non-empty until pmap_ptelist_alloc() completes.
         */
        if (pv_vafree == 0 || (m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
            VM_ALLOC_NOOBJ | VM_ALLOC_WIRED)) == NULL) {
                if (try) {
                        pv_entry_count--;
                        PV_STAT(pc_chunk_tryfail++);
                        return (NULL);
                }
                m = pmap_pv_reclaim(pmap);
                if (m == NULL)
                        goto retry;
        }
        PV_STAT(pc_chunk_count++);
        PV_STAT(pc_chunk_allocs++);
        pc = (struct pv_chunk *)pmap_ptelist_alloc(&pv_vafree);
        pmap_qenter((vm_offset_t)pc, &m, 1);
        pc->pc_pmap = pmap;
        pc->pc_map[0] = pc_freemask[0] & ~1ul;  /* preallocated bit 0 */
        for (field = 1; field < _NPCM; field++)
                pc->pc_map[field] = pc_freemask[field];
        TAILQ_INSERT_TAIL(&pv_chunks, pc, pc_lru);
        pv = &pc->pc_pventry[0];
        TAILQ_INSERT_HEAD(&pmap->pm_pvchunk, pc, pc_list);
        PV_STAT(pv_entry_spare += _NPCPV - 1);
        return (pv);
}

/*
 *      Remove the given range of addresses from the specified map.
 *
 *      It is assumed that the start and end are properly
 *      rounded to the page size.
 */
#define PMAP_REMOVE_CLEAN_LIST_SIZE     3
void
pmap_remove(pmap_t pm, vm_offset_t sva, vm_offset_t eva)
{
        struct l2_bucket *l2b;
        vm_offset_t next_bucket;
        pt_entry_t *ptep;
        u_int total;
        u_int mappings, is_exec, is_refd;
        int flushall = 0;


        /*
         * we lock in the pmap => pv_head direction
         */

        rw_wlock(&pvh_global_lock);
        PMAP_LOCK(pm);
        total = 0;
        while (sva < eva) {
                /*
                 * Do one L2 bucket's worth at a time.
                 */
                next_bucket = L2_NEXT_BUCKET(sva);
                if (next_bucket > eva)
                        next_bucket = eva;

                l2b = pmap_get_l2_bucket(pm, sva);
                if (l2b == NULL) {
                        sva = next_bucket;
                        continue;
                }

                ptep = &l2b->l2b_kva[l2pte_index(sva)];
                mappings = 0;

                while (sva < next_bucket) {
                        struct vm_page *pg;
                        pt_entry_t pte;
                        vm_paddr_t pa;

                        pte = *ptep;

                        if (pte == 0) {
                                /*
                                 * Nothing here, move along
                                 */
                                sva += PAGE_SIZE;
                                ptep++;
                                continue;
                        }

                        pm->pm_stats.resident_count--;
                        pa = l2pte_pa(pte);
                        is_exec = 0;
                        is_refd = 1;

                        /*
                         * Update flags. In a number of circumstances,
                         * we could cluster a lot of these and do a
                         * number of sequential pages in one go.
                         */
                        if ((pg = PHYS_TO_VM_PAGE(pa)) != NULL) {
                                struct pv_entry *pve;

                                pve = pmap_remove_pv(pg, pm, sva);
                                if (pve) {
                                        is_exec = PV_BEEN_EXECD(pve->pv_flags);
                                        is_refd = PV_BEEN_REFD(pve->pv_flags);
                                        pmap_free_pv_entry(pm, pve);
                                }
                        }

                        if (pmap_is_current(pm)) {
                                total++;
                                if (total < PMAP_REMOVE_CLEAN_LIST_SIZE) {
                                        if (is_exec)
                                                cpu_tlb_flushID_SE(sva);
                                        else if (is_refd)
                                                cpu_tlb_flushD_SE(sva);
                                } else if (total == PMAP_REMOVE_CLEAN_LIST_SIZE) {
                                        flushall = 1;
                                }
                        }
                        *ptep = 0;
                        PTE_SYNC(ptep);

                        sva += PAGE_SIZE;
                        ptep++;
                        mappings++;
                }

                pmap_free_l2_bucket(pm, l2b, mappings);
        }

        rw_wunlock(&pvh_global_lock);
        if (flushall)
                cpu_tlb_flushID();
        PMAP_UNLOCK(pm);
}

/*
 * pmap_zero_page()
 *
 * Zero a given physical page by mapping it at a page hook point.
 * In doing the zero page op, the page we zero is mapped cachable, as with
 * StrongARM accesses to non-cached pages are non-burst making writing
 * _any_ bulk data very slow.
 */
static void
pmap_zero_page_gen(vm_page_t pg, int off, int size)
{

        vm_paddr_t phys = VM_PAGE_TO_PHYS(pg);
        if (!TAILQ_EMPTY(&pg->md.pv_list))
                panic("pmap_zero_page: page has mappings");

        mtx_lock(&cmtx);
        /*
         * Hook in the page, zero it, invalidate the TLB as needed.
         *
         * Note the temporary zero-page mapping must be a non-cached page in
         * order to work without corruption when write-allocate is enabled.
         */
        *cdst_pte = L2_S_PROTO | phys | pte_l2_s_cache_mode;
        pmap_set_prot(cdst_pte, VM_PROT_WRITE, 0);
        PTE_SYNC(cdst_pte);
        cpu_tlb_flushD_SE(cdstp);
        cpu_cpwait();
        if (off || size != PAGE_SIZE)
                bzero((void *)(cdstp + off), size);
        else
                bzero_page(cdstp);

        /*
         * Although aliasing is not possible if we use 
         * cdstp temporary mappings with memory that 
         * will be mapped later as non-cached or with write-through 
         * caches we might end up overwriting it when calling wbinv_all
         * So make sure caches are clean after copy operation
         */
        cpu_idcache_wbinv_range(cdstp, size);
        pmap_l2cache_wbinv_range(cdstp, phys, size);

        mtx_unlock(&cmtx);
}

/*
 *      pmap_zero_page zeros the specified hardware page by mapping
 *      the page into KVM and using bzero to clear its contents.
 */
void
pmap_zero_page(vm_page_t m)
{
        pmap_zero_page_gen(m, 0, PAGE_SIZE);
}


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

        pmap_zero_page_gen(m, off, size);
}


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

        pmap_zero_page(m);
}

/*
 *      pmap_copy_page copies the specified (machine independent)
 *      page by mapping the page into virtual memory and using
 *      bcopy to copy the page, one machine dependent page at a
 *      time.
 */

/*
 * pmap_copy_page()
 *
 * Copy one physical page into another, by mapping the pages into
 * hook points. The same comment regarding cachability as in
 * pmap_zero_page also applies here.
 */
void
pmap_copy_page_generic(vm_paddr_t src, vm_paddr_t dst)
{
        /*
         * Hold the source page's lock for the duration of the copy
         * so that no other mappings can be created while we have a
         * potentially aliased mapping.
         * Map the pages into the page hook points, copy them, and purge
         * the cache for the appropriate page. Invalidate the TLB
         * as required.
         */
        mtx_lock(&cmtx);

        /* For ARMv6 using System bit is deprecated and mapping with AP
         * bits set to 0x0 makes page not accessible. csrc_pte is mapped
         * read/write until proper mapping defines are created for ARMv6.
         */
        *csrc_pte = L2_S_PROTO | src | pte_l2_s_cache_mode;
        pmap_set_prot(csrc_pte, VM_PROT_READ, 0);
        PTE_SYNC(csrc_pte);

        *cdst_pte = L2_S_PROTO | dst | pte_l2_s_cache_mode;
        pmap_set_prot(cdst_pte, VM_PROT_READ | VM_PROT_WRITE, 0);
        PTE_SYNC(cdst_pte);

        cpu_tlb_flushD_SE(csrcp);
        cpu_tlb_flushD_SE(cdstp);
        cpu_cpwait();

        /*
         * Although aliasing is not possible if we use 
         * cdstp temporary mappings with memory that 
         * will be mapped later as non-cached or with write-through 
         * caches we might end up overwriting it when calling wbinv_all
         * So make sure caches are clean after copy operation
         */
        bcopy_page(csrcp, cdstp);

        cpu_idcache_wbinv_range(cdstp, PAGE_SIZE);
        pmap_l2cache_wbinv_range(cdstp, dst, PAGE_SIZE);

        mtx_unlock(&cmtx);
}

int unmapped_buf_allowed = 1;

void
pmap_copy_pages(vm_page_t ma[], vm_offset_t a_offset, vm_page_t mb[],
    vm_offset_t b_offset, int xfersize)
{
        vm_page_t a_pg, b_pg;
        vm_offset_t a_pg_offset, b_pg_offset;
        int cnt;

        mtx_lock(&cmtx);
        while (xfersize > 0) {
                a_pg = ma[a_offset >> PAGE_SHIFT];
                a_pg_offset = a_offset & PAGE_MASK;
                cnt = min(xfersize, PAGE_SIZE - a_pg_offset);
                b_pg = mb[b_offset >> PAGE_SHIFT];
                b_pg_offset = b_offset & PAGE_MASK;
                cnt = min(cnt, PAGE_SIZE - b_pg_offset);
                *csrc_pte = L2_S_PROTO | VM_PAGE_TO_PHYS(a_pg) |
                    pte_l2_s_cache_mode;
                pmap_set_prot(csrc_pte, VM_PROT_READ, 0);
                PTE_SYNC(csrc_pte);
                *cdst_pte = L2_S_PROTO | VM_PAGE_TO_PHYS(b_pg) |
                    pte_l2_s_cache_mode;
                pmap_set_prot(cdst_pte, VM_PROT_READ | VM_PROT_WRITE, 0);
                PTE_SYNC(cdst_pte);
                cpu_tlb_flushD_SE(csrcp);
                cpu_tlb_flushD_SE(cdstp);
                cpu_cpwait();
                bcopy((char *)csrcp + a_pg_offset, (char *)cdstp + b_pg_offset,
                    cnt);
                cpu_idcache_wbinv_range(cdstp + b_pg_offset, cnt);
                pmap_l2cache_wbinv_range(cdstp + b_pg_offset,
                    VM_PAGE_TO_PHYS(b_pg) + b_pg_offset, cnt);
                xfersize -= cnt;
                a_offset += cnt;
                b_offset += cnt;
        }
        mtx_unlock(&cmtx);
}

void
pmap_copy_page(vm_page_t src, vm_page_t dst)
{

        if (_arm_memcpy && PAGE_SIZE >= _min_memcpy_size &&
            _arm_memcpy((void *)VM_PAGE_TO_PHYS(dst),
            (void *)VM_PAGE_TO_PHYS(src), PAGE_SIZE, IS_PHYSICAL) == 0)
                return;

        pmap_copy_page_generic(VM_PAGE_TO_PHYS(src), VM_PAGE_TO_PHYS(dst));
}

/*
 * this routine returns true if a physical page resides
 * in the given pmap.
 */
boolean_t
pmap_page_exists_quick(pmap_t pmap, vm_page_t m)
{
        pv_entry_t pv;
        int loops = 0;
        boolean_t rv;

        KASSERT((m->oflags & VPO_UNMANAGED) == 0,
            ("pmap_page_exists_quick: page %p is not managed", m));
        rv = FALSE;
        rw_wlock(&pvh_global_lock);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                if (PV_PMAP(pv) == pmap) {
                        rv = TRUE;
                        break;
                }
                loops++;
                if (loops >= 16)
                        break;
        }

        rw_wunlock(&pvh_global_lock);
        return (rv);
}

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

        count = 0;
        if ((m->flags & PG_FICTITIOUS) != 0)
                return (count);
        rw_wlock(&pvh_global_lock);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list)
                if ((pv->pv_flags & PVF_WIRED) != 0)
                        count++;
        rw_wunlock(&pvh_global_lock);
        return (count);
}

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

        KASSERT((m->oflags & VPO_UNMANAGED) == 0,
            ("pmap_is_referenced: page %p is not managed", m));
        return ((m->md.pvh_attrs & PVF_REF) != 0);
}

/*
 *      pmap_ts_referenced:
 *
 *      Return the count of reference bits for a page, clearing all of them.
 */
int
pmap_ts_referenced(vm_page_t m)
{

        KASSERT((m->oflags & VPO_UNMANAGED) == 0,
            ("pmap_ts_referenced: page %p is not managed", m));
        return (pmap_clearbit(m, PVF_REF));
}


boolean_t
pmap_is_modified(vm_page_t m)
{

        KASSERT((m->oflags & VPO_UNMANAGED) == 0,
            ("pmap_is_modified: page %p is not managed", m));
        if (m->md.pvh_attrs & PVF_MOD)
                return (TRUE);

        return(FALSE);
}


/*
 *      Clear the modify bits on the specified physical page.
 */
void
pmap_clear_modify(vm_page_t m)
{

        KASSERT((m->oflags & VPO_UNMANAGED) == 0,
            ("pmap_clear_modify: page %p is not managed", m));
        VM_OBJECT_ASSERT_WLOCKED(m->object);
        KASSERT((m->oflags & VPO_BUSY) == 0,
            ("pmap_clear_modify: page %p is busy", m));

        /*
         * If the page is not PGA_WRITEABLE, then no mappings can be modified.
         * If the object containing the page is locked and the page is not
         * VPO_BUSY, then PGA_WRITEABLE cannot be concurrently set.
         */
        if ((m->aflags & PGA_WRITEABLE) == 0)
                return;

        if (m->md.pvh_attrs & PVF_MOD)
                pmap_clearbit(m, PVF_MOD);
}


/*
 *      pmap_clear_reference:
 *
 *      Clear the reference bit on the specified physical page.
 */
void
pmap_clear_reference(vm_page_t m)
{

        KASSERT((m->oflags & VPO_UNMANAGED) == 0,
            ("pmap_clear_reference: page %p is not managed", m));
        if (m->md.pvh_attrs & PVF_REF)
                pmap_clearbit(m, PVF_REF);
}


/*
 * Clear the write and modified bits in each of the given page's mappings.
 */
void
pmap_remove_write(vm_page_t m)
{
        KASSERT((m->oflags & VPO_UNMANAGED) == 0,
            ("pmap_remove_write: page %p is not managed", m));

        /*
         * If the page is not VPO_BUSY, then PGA_WRITEABLE cannot be set by
         * another thread while the object is locked.  Thus, if PGA_WRITEABLE
         * is clear, no page table entries need updating.
         */
        VM_OBJECT_ASSERT_WLOCKED(m->object);
        if ((m->oflags & VPO_BUSY) != 0 ||
            (m->aflags & PGA_WRITEABLE) != 0)
                pmap_clearbit(m, PVF_WRITE);
}


/*
 * perform the pmap work for mincore
 */
int
pmap_mincore(pmap_t pmap, vm_offset_t addr, vm_paddr_t *locked_pa)
{
        struct l2_bucket *l2b;
        pt_entry_t *ptep, pte;
        vm_paddr_t pa;
        vm_page_t m;
        int val;
        boolean_t managed;

        PMAP_LOCK(pmap);
retry:
        l2b = pmap_get_l2_bucket(pmap, addr);
        if (l2b == NULL) {
                val = 0;
                goto out;
        }
        ptep = &l2b->l2b_kva[l2pte_index(addr)];
        pte = *ptep;
        if (!l2pte_valid(pte)) {
                val = 0;
                goto out;
        }
        val = MINCORE_INCORE;
        if (L2_S_WRITABLE(pte))
                val |= MINCORE_MODIFIED | MINCORE_MODIFIED_OTHER;
        managed = FALSE;
        pa = l2pte_pa(pte);
        m = PHYS_TO_VM_PAGE(pa);
        if (m != NULL && (m->oflags & VPO_UNMANAGED) == 0)
                managed = TRUE;
        if (managed) {
                /*
                 * The ARM pmap tries to maintain a per-mapping
                 * reference bit.  The trouble is that it's kept in
                 * the PV entry, not the PTE, so it's costly to access
                 * here.  You would need to acquire the pvh global
                 * lock, call pmap_find_pv(), and introduce a custom
                 * version of vm_page_pa_tryrelock() that releases and
                 * reacquires the pvh global lock.  In the end, I
                 * doubt it's worthwhile.  This may falsely report
                 * the given address as referenced.
                 */
                if ((m->md.pvh_attrs & PVF_REF) != 0)
                        val |= MINCORE_REFERENCED | MINCORE_REFERENCED_OTHER;
        }
        if ((val & (MINCORE_MODIFIED_OTHER | MINCORE_REFERENCED_OTHER)) !=
            (MINCORE_MODIFIED_OTHER | MINCORE_REFERENCED_OTHER) && managed) {
                /* Ensure that "PHYS_TO_VM_PAGE(pa)->object" doesn't change. */
                if (vm_page_pa_tryrelock(pmap, pa, locked_pa))
                        goto retry;
        } else
out:
                PA_UNLOCK_COND(*locked_pa);
        PMAP_UNLOCK(pmap);
        return (val);
}

void
pmap_sync_icache(pmap_t pm, vm_offset_t va, vm_size_t sz)
{
}

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


/*
 * 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(vm_offset_t pa, vm_size_t size)
{
        vm_offset_t va, tmpva, offset;

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

        GIANT_REQUIRED;

        va = kmem_alloc_nofault(kernel_map, size);
        if (!va)
                panic("pmap_mapdev: Couldn't alloc kernel virtual memory");
        for (tmpva = va; size > 0;) {
                pmap_kenter_internal(tmpva, pa, 0);
                size -= PAGE_SIZE;
                tmpva += PAGE_SIZE;
                pa += PAGE_SIZE;
        }

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

/*
 * pmap_map_section:
 *
 *      Create a single section mapping.
 */
void
pmap_map_section(vm_offset_t l1pt, vm_offset_t va, vm_offset_t pa,
    int prot, int cache)
{
        pd_entry_t *pde = (pd_entry_t *) l1pt;
        pd_entry_t fl;

        KASSERT(((va | pa) & L1_S_OFFSET) == 0, ("ouin2"));

        fl = l1_mem_types[cache];

        pde[va >> L1_S_SHIFT] = L1_S_PROTO | pa |
            L1_S_PROT(PTE_KERNEL, prot) | fl | L1_S_DOM(PMAP_DOMAIN_KERNEL);
        PTE_SYNC(&pde[va >> L1_S_SHIFT]);
}

/*
 * pmap_link_l2pt:
 *
 *      Link the L2 page table specified by l2pv.pv_pa into the L1
 *      page table at the slot for "va".
 */
void
pmap_link_l2pt(vm_offset_t l1pt, vm_offset_t va, struct pv_addr *l2pv)
{
        pd_entry_t *pde = (pd_entry_t *) l1pt, proto;
        u_int slot = va >> L1_S_SHIFT;

        proto = L1_S_DOM(PMAP_DOMAIN_KERNEL) | L1_C_PROTO;

#ifdef VERBOSE_INIT_ARM
        printf("pmap_link_l2pt: pa=0x%x va=0x%x\n", l2pv->pv_pa, l2pv->pv_va);
#endif

        pde[slot + 0] = proto | (l2pv->pv_pa + 0x000);
        PTE_SYNC(&pde[slot]);

        SLIST_INSERT_HEAD(&kernel_pt_list, l2pv, pv_list);

}

/*
 * pmap_map_entry
 *
 *      Create a single page mapping.
 */
void
pmap_map_entry(vm_offset_t l1pt, vm_offset_t va, vm_offset_t pa, int prot,
    int cache)
{
        pd_entry_t *pde = (pd_entry_t *) l1pt;
        pt_entry_t fl;
        pt_entry_t *pte;

        KASSERT(((va | pa) & PAGE_MASK) == 0, ("ouin"));

        fl = l2s_mem_types[cache];

        if ((pde[va >> L1_S_SHIFT] & L1_TYPE_MASK) != L1_TYPE_C)
                panic("pmap_map_entry: no L2 table for VA 0x%08x", va);

        pte = (pt_entry_t *) kernel_pt_lookup(pde[L1_IDX(va)] & L1_C_ADDR_MASK);

        if (pte == NULL)
                panic("pmap_map_entry: can't find L2 table for VA 0x%08x", va);

        pte[l2pte_index(va)] = L2_S_PROTO | pa | fl;
        pmap_set_prot(&pte[l2pte_index(va)], prot, 0);
        PTE_SYNC(&pte[l2pte_index(va)]);
}

/*
 * pmap_map_chunk:
 *
 *      Map a chunk of memory using the most efficient mappings
 *      possible (section. large page, small page) into the
 *      provided L1 and L2 tables at the specified virtual address.
 */
vm_size_t
pmap_map_chunk(vm_offset_t l1pt, vm_offset_t va, vm_offset_t pa,
    vm_size_t size, int prot, int type)
{
        pd_entry_t *pde = (pd_entry_t *) l1pt;
        pt_entry_t *pte, f1, f2s, f2l;
        vm_size_t resid;
        int i;

        resid = (size + (PAGE_SIZE - 1)) & ~(PAGE_SIZE - 1);

        if (l1pt == 0)
                panic("pmap_map_chunk: no L1 table provided");

#ifdef VERBOSE_INIT_ARM
        printf("pmap_map_chunk: pa=0x%x va=0x%x size=0x%x resid=0x%x "
            "prot=0x%x type=%d\n", pa, va, size, resid, prot, type);
#endif

        f1 = l1_mem_types[type];
        f2l = l2l_mem_types[type];
        f2s = l2s_mem_types[type];

        size = resid;

        while (resid > 0) {
                /* See if we can use a section mapping. */
                if (L1_S_MAPPABLE_P(va, pa, resid)) {
#ifdef VERBOSE_INIT_ARM
                        printf("S");
#endif
                        pde[va >> L1_S_SHIFT] = L1_S_PROTO | pa |
                            L1_S_PROT(PTE_KERNEL, prot) | f1 |
                            L1_S_DOM(PMAP_DOMAIN_KERNEL);
                        PTE_SYNC(&pde[va >> L1_S_SHIFT]);
                        va += L1_S_SIZE;
                        pa += L1_S_SIZE;
                        resid -= L1_S_SIZE;
                        continue;
                }

                /*
                 * Ok, we're going to use an L2 table.  Make sure
                 * one is actually in the corresponding L1 slot
                 * for the current VA.
                 */
                if ((pde[va >> L1_S_SHIFT] & L1_TYPE_MASK) != L1_TYPE_C)
                        panic("pmap_map_chunk: no L2 table for VA 0x%08x", va);

                pte = (pt_entry_t *) kernel_pt_lookup(
                    pde[L1_IDX(va)] & L1_C_ADDR_MASK);
                if (pte == NULL)
                        panic("pmap_map_chunk: can't find L2 table for VA"
                            "0x%08x", va);
                /* See if we can use a L2 large page mapping. */
                if (L2_L_MAPPABLE_P(va, pa, resid)) {
#ifdef VERBOSE_INIT_ARM
                        printf("L");
#endif
                        for (i = 0; i < 16; i++) {
                                pte[l2pte_index(va) + i] =
                                    L2_L_PROTO | pa |
                                    L2_L_PROT(PTE_KERNEL, prot) | f2l;
                                PTE_SYNC(&pte[l2pte_index(va) + i]);
                        }
                        va += L2_L_SIZE;
                        pa += L2_L_SIZE;
                        resid -= L2_L_SIZE;
                        continue;
                }

                /* Use a small page mapping. */
#ifdef VERBOSE_INIT_ARM
                printf("P");
#endif
                pte[l2pte_index(va)] = L2_S_PROTO | pa | f2s;
                pmap_set_prot(&pte[l2pte_index(va)], prot, 0);
                PTE_SYNC(&pte[l2pte_index(va)]);
                va += PAGE_SIZE;
                pa += PAGE_SIZE;
                resid -= PAGE_SIZE;
        }
#ifdef VERBOSE_INIT_ARM
        printf("\n");
#endif
        return (size);

}

/********************** Static device map routines ***************************/

static const struct pmap_devmap *pmap_devmap_table;

/*
 * Register the devmap table.  This is provided in case early console
 * initialization needs to register mappings created by bootstrap code
 * before pmap_devmap_bootstrap() is called.
 */
void
pmap_devmap_register(const struct pmap_devmap *table)
{

        pmap_devmap_table = table;
}

/*
 * Map all of the static regions in the devmap table, and remember
 * the devmap table so other parts of the kernel can look up entries
 * later.
 */
void
pmap_devmap_bootstrap(vm_offset_t l1pt, const struct pmap_devmap *table)
{
        int i;

        pmap_devmap_table = table;

        for (i = 0; pmap_devmap_table[i].pd_size != 0; i++) {
#ifdef VERBOSE_INIT_ARM
                printf("devmap: %08x -> %08x @ %08x\n",
                    pmap_devmap_table[i].pd_pa,
                    pmap_devmap_table[i].pd_pa +
                        pmap_devmap_table[i].pd_size - 1,
                    pmap_devmap_table[i].pd_va);
#endif
                pmap_map_chunk(l1pt, pmap_devmap_table[i].pd_va,
                    pmap_devmap_table[i].pd_pa,
                    pmap_devmap_table[i].pd_size,
                    pmap_devmap_table[i].pd_prot,
                    pmap_devmap_table[i].pd_cache);
        }
}

const struct pmap_devmap *
pmap_devmap_find_pa(vm_paddr_t pa, vm_size_t size)
{
        int i;

        if (pmap_devmap_table == NULL)
                return (NULL);

        for (i = 0; pmap_devmap_table[i].pd_size != 0; i++) {
                if (pa >= pmap_devmap_table[i].pd_pa &&
                    pa + size <= pmap_devmap_table[i].pd_pa +
                                 pmap_devmap_table[i].pd_size)
                        return (&pmap_devmap_table[i]);
        }

        return (NULL);
}

const struct pmap_devmap *
pmap_devmap_find_va(vm_offset_t va, vm_size_t size)
{
        int i;

        if (pmap_devmap_table == NULL)
                return (NULL);

        for (i = 0; pmap_devmap_table[i].pd_size != 0; i++) {
                if (va >= pmap_devmap_table[i].pd_va &&
                    va + size <= pmap_devmap_table[i].pd_va +
                                 pmap_devmap_table[i].pd_size)
                        return (&pmap_devmap_table[i]);
        }

        return (NULL);
}

int
pmap_dmap_iscurrent(pmap_t pmap)
{
        return(pmap_is_current(pmap));
}

void
pmap_page_set_memattr(vm_page_t m, vm_memattr_t ma)
{
        /* 
         * Remember the memattr in a field that gets used to set the appropriate
         * bits in the PTEs as mappings are established.
         */
        m->md.pv_memattr = ma;

        /*
         * It appears that this function can only be called before any mappings
         * for the page are established on ARM.  If this ever changes, this code
         * will need to walk the pv_list and make each of the existing mappings
         * uncacheable, being careful to sync caches and PTEs (and maybe
         * invalidate TLB?) for any current mapping it modifies.
         */
        if (m->md.pv_kva != 0 || TAILQ_FIRST(&m->md.pv_list) != NULL)
                panic("Can't change memattr on page with existing mappings");
}