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[FreeBSD/FreeBSD.git] / sys / i386 / i386 / pmap.c

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

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

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

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

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

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

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

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

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

#ifndef PMAP_SHPGPERPROC
#define PMAP_SHPGPERPROC 200
#endif

#if defined(DIAGNOSTIC)
#define PMAP_DIAGNOSTIC
#endif

#if !defined(PMAP_DIAGNOSTIC)
#define PMAP_INLINE __inline
#else
#define PMAP_INLINE
#endif

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

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

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

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

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

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

static int nkpt;
vm_offset_t kernel_vm_end;
extern u_int32_t KERNend;

#ifdef PAE
static uma_zone_t pdptzone;
#endif

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

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

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

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

#ifdef SMP
extern pt_entry_t *SMPpt;
#endif
static pt_entry_t *PMAP1 = 0, *PMAP2;
static pt_entry_t *PADDR1 = 0, *PADDR2;
#ifdef SMP
static int PMAP1cpu;
static int PMAP1changedcpu;
SYSCTL_INT(_debug, OID_AUTO, PMAP1changedcpu, CTLFLAG_RD, 
           &PMAP1changedcpu, 0,
           "Number of times pmap_pte_quick changed CPU with same PMAP1");
#endif
static int PMAP1changed;
SYSCTL_INT(_debug, OID_AUTO, PMAP1changed, CTLFLAG_RD, 
           &PMAP1changed, 0,
           "Number of times pmap_pte_quick changed PMAP1");
static int PMAP1unchanged;
SYSCTL_INT(_debug, OID_AUTO, PMAP1unchanged, CTLFLAG_RD, 
           &PMAP1unchanged, 0,
           "Number of times pmap_pte_quick didn't change PMAP1");
static struct mtx PMAP2mutex;

static void     free_pv_entry(pmap_t pmap, pv_entry_t pv);
static pv_entry_t get_pv_entry(pmap_t locked_pmap, int try);

static vm_page_t pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va,
    vm_page_t m, vm_prot_t prot, vm_page_t mpte);
static int pmap_remove_pte(pmap_t pmap, pt_entry_t *ptq, vm_offset_t sva);
static void pmap_remove_page(struct pmap *pmap, vm_offset_t va);
static void pmap_remove_entry(struct pmap *pmap, vm_page_t m,
                                        vm_offset_t va);
static void pmap_insert_entry(pmap_t pmap, vm_offset_t va, vm_page_t m);
static boolean_t pmap_try_insert_pv_entry(pmap_t pmap, vm_offset_t va,
    vm_page_t m);

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

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

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

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

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

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

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

        virtual_end = VM_MAX_KERNEL_ADDRESS;

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

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

        va = virtual_avail;
        pte = vtopte(va);

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

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

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

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

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

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

        virtual_avail = va;

        *CMAP1 = 0;

#ifdef XBOX
        /* FIXME: This is gross, but needed for the XBOX. Since we are in such
         * an early stadium, we cannot yet neatly map video memory ... :-(
         * Better fixes are very welcome! */
        if (!arch_i386_is_xbox)
#endif
        for (i = 0; i < NKPT; i++)
                PTD[i] = 0;

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

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

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

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

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

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

        if (pgeflag == 0)
                return;

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

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

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

        TAILQ_INIT(&m->md.pv_list);
        m->md.pv_list_count = 0;
}

#ifdef PAE

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

static void *
pmap_pdpt_allocf(uma_zone_t zone, int bytes, u_int8_t *flags, int wait)
{
        *flags = UMA_SLAB_PRIV;
        return (contigmalloc(PAGE_SIZE, M_PMAPPDPT, 0, 0x0ULL, 0xffffffffULL,
            1, 0));
}
#endif

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

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

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

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

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

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


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

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

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


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

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

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

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

        /* If we don't support PAT, map extended modes to older ones. */
        if (!(cpu_feature & CPUID_PAT)) {
                switch (mode) {
                case PAT_UNCACHEABLE:
                case PAT_WRITE_THROUGH:
                case PAT_WRITE_BACK:
                        break;
                case PAT_UNCACHED:
                case PAT_WRITE_COMBINING:
                case PAT_WRITE_PROTECTED:
                        mode = PAT_UNCACHEABLE;
                        break;
                }
        }
        
        /* Map the caching mode to a PAT index. */
        switch (mode) {
#ifdef PAT_WORKS
        case PAT_UNCACHEABLE:
                pat_index = 3;
                break;
        case PAT_WRITE_THROUGH:
                pat_index = 1;
                break;
        case PAT_WRITE_BACK:
                pat_index = 0;
                break;
        case PAT_UNCACHED:
                pat_index = 2;
                break;
        case PAT_WRITE_COMBINING:
                pat_index = 5;
                break;
        case PAT_WRITE_PROTECTED:
                pat_index = 4;
                break;
#else
        case PAT_UNCACHED:
        case PAT_UNCACHEABLE:
        case PAT_WRITE_PROTECTED:
                pat_index = 3;
                break;
        case PAT_WRITE_THROUGH:
                pat_index = 1;
                break;
        case PAT_WRITE_BACK:
                pat_index = 0;
                break;
        case PAT_WRITE_COMBINING:
                pat_index = 2;
                break;
#endif
        default:
                panic("Unknown caching mode %d\n", mode);
        }       

        /* Map the 3-bit index value into the PAT, PCD, and PWT bits. */
        cache_bits = 0;
        if (pat_index & 0x4)
                cache_bits |= pat_flag;
        if (pat_index & 0x2)
                cache_bits |= PG_NC_PCD;
        if (pat_index & 0x1)
                cache_bits |= PG_NC_PWT;
        return (cache_bits);
}
#ifdef SMP
/*
 * For SMP, these functions have to use the IPI mechanism for coherence.
 */
void
pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
{
        u_int cpumask;
        u_int other_cpus;

        if (smp_started) {
                if (!(read_eflags() & PSL_I))
                        panic("%s: interrupts disabled", __func__);
                mtx_lock_spin(&smp_ipi_mtx);
        } else
                critical_enter();
        /*
         * We need to disable interrupt preemption but MUST NOT have
         * interrupts disabled here.
         * XXX we may need to hold schedlock to get a coherent pm_active
         * XXX critical sections disable interrupts again
         */
        if (pmap == kernel_pmap || pmap->pm_active == all_cpus) {
                invlpg(va);
                smp_invlpg(va);
        } else {
                cpumask = PCPU_GET(cpumask);
                other_cpus = PCPU_GET(other_cpus);
                if (pmap->pm_active & cpumask)
                        invlpg(va);
                if (pmap->pm_active & other_cpus)
                        smp_masked_invlpg(pmap->pm_active & other_cpus, va);
        }
        if (smp_started)
                mtx_unlock_spin(&smp_ipi_mtx);
        else
                critical_exit();
}

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

        if (smp_started) {
                if (!(read_eflags() & PSL_I))
                        panic("%s: interrupts disabled", __func__);
                mtx_lock_spin(&smp_ipi_mtx);
        } else
                critical_enter();
        /*
         * We need to disable interrupt preemption but MUST NOT have
         * interrupts disabled here.
         * XXX we may need to hold schedlock to get a coherent pm_active
         * XXX critical sections disable interrupts again
         */
        if (pmap == kernel_pmap || pmap->pm_active == all_cpus) {
                for (addr = sva; addr < eva; addr += PAGE_SIZE)
                        invlpg(addr);
                smp_invlpg_range(sva, eva);
        } else {
                cpumask = PCPU_GET(cpumask);
                other_cpus = PCPU_GET(other_cpus);
                if (pmap->pm_active & cpumask)
                        for (addr = sva; addr < eva; addr += PAGE_SIZE)
                                invlpg(addr);
                if (pmap->pm_active & other_cpus)
                        smp_masked_invlpg_range(pmap->pm_active & other_cpus,
                            sva, eva);
        }
        if (smp_started)
                mtx_unlock_spin(&smp_ipi_mtx);
        else
                critical_exit();
}

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

        if (smp_started) {
                if (!(read_eflags() & PSL_I))
                        panic("%s: interrupts disabled", __func__);
                mtx_lock_spin(&smp_ipi_mtx);
        } else
                critical_enter();
        /*
         * We need to disable interrupt preemption but MUST NOT have
         * interrupts disabled here.
         * XXX we may need to hold schedlock to get a coherent pm_active
         * XXX critical sections disable interrupts again
         */
        if (pmap == kernel_pmap || pmap->pm_active == all_cpus) {
                invltlb();
                smp_invltlb();
        } else {
                cpumask = PCPU_GET(cpumask);
                other_cpus = PCPU_GET(other_cpus);
                if (pmap->pm_active & cpumask)
                        invltlb();
                if (pmap->pm_active & other_cpus)
                        smp_masked_invltlb(pmap->pm_active & other_cpus);
        }
        if (smp_started)
                mtx_unlock_spin(&smp_ipi_mtx);
        else
                critical_exit();
}

void
pmap_invalidate_cache(void)
{

        if (smp_started) {
                if (!(read_eflags() & PSL_I))
                        panic("%s: interrupts disabled", __func__);
                mtx_lock_spin(&smp_ipi_mtx);
        } else
                critical_enter();
        /*
         * We need to disable interrupt preemption but MUST NOT have
         * interrupts disabled here.
         * XXX we may need to hold schedlock to get a coherent pm_active
         * XXX critical sections disable interrupts again
         */
        wbinvd();
        smp_cache_flush();
        if (smp_started)
                mtx_unlock_spin(&smp_ipi_mtx);
        else
                critical_exit();
}
#else /* !SMP */
/*
 * Normal, non-SMP, 486+ invalidation functions.
 * We inline these within pmap.c for speed.
 */
PMAP_INLINE void
pmap_invalidate_page(pmap_t pmap, vm_offset_t va)
{

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

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

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

PMAP_INLINE void
pmap_invalidate_all(pmap_t pmap)
{

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

PMAP_INLINE void
pmap_invalidate_cache(void)
{

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

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

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

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

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

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

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

static __inline void
invlcaddr(void *caddr)
{

        invlpg((u_int)caddr);
}

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

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

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

        rtval = 0;
        PMAP_LOCK(pmap);
        pde = pmap->pm_pdir[va >> PDRSHIFT];
        if (pde != 0) {
                if ((pde & PG_PS) != 0) {
                        rtval = (pde & ~PDRMASK) | (va & PDRMASK);
                        PMAP_UNLOCK(pmap);
                        return rtval;
                }
                pte = pmap_pte(pmap, va);
                rtval = (*pte & PG_FRAME) | (va & PAGE_MASK);
                pmap_pte_release(pte);
        }
        PMAP_UNLOCK(pmap);
        return (rtval);
}

/*
 *      Routine:        pmap_extract_and_hold
 *      Function:
 *              Atomically extract and hold the physical page
 *              with the given pmap and virtual address pair
 *              if that mapping permits the given protection.
 */
vm_page_t
pmap_extract_and_hold(pmap_t pmap, vm_offset_t va, vm_prot_t prot)
{
        pd_entry_t pde;
        pt_entry_t pte;
        vm_page_t m;

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

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

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

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

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

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

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

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

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

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


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

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

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

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

/***************************************************
 * Page table page management routines.....
 ***************************************************/

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

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

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

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

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

        vm_page_free_zero(m);
        atomic_subtract_int(&cnt.v_wire_count, 1);
        return 1;
}

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

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

void
pmap_pinit0(pmap_t pmap)
{

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

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

        PMAP_LOCK_INIT(pmap);

        /*
         * No need to allocate page table space yet but we do need a valid
         * page directory table.
         */
        if (pmap->pm_pdir == NULL) {
                pmap->pm_pdir = (pd_entry_t *)kmem_alloc_nofault(kernel_map,
                    NBPTD);
#ifdef PAE
                pmap->pm_pdpt = uma_zalloc(pdptzone, M_WAITOK | M_ZERO);
                KASSERT(((vm_offset_t)pmap->pm_pdpt &
                    ((NPGPTD * sizeof(pdpt_entry_t)) - 1)) == 0,
                    ("pmap_pinit: pdpt misaligned"));
                KASSERT(pmap_kextract((vm_offset_t)pmap->pm_pdpt) < (4ULL<<30),
                    ("pmap_pinit: pdpt above 4g"));
#endif
        }

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

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

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

        mtx_lock_spin(&allpmaps_lock);
        LIST_INSERT_HEAD(&allpmaps, pmap, pm_list);
        mtx_unlock_spin(&allpmaps_lock);
        /* Wire in kernel global address entries. */
        /* XXX copies current process, does not fill in MPPTDI */
        bcopy(PTD + KPTDI, pmap->pm_pdir + KPTDI, nkpt * sizeof(pd_entry_t));
#ifdef SMP
        pmap->pm_pdir[MPPTDI] = PTD[MPPTDI];
#endif

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

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

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

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

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

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

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

        pmap->pm_stats.resident_count++;

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

        return m;
}

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

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

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

        /*
         * This supports switching from a 4MB page to a
         * normal 4K page.
         */
        if (ptepa & PG_PS) {
                pmap->pm_pdir[ptepindex] = 0;
                ptepa = 0;
                pmap->pm_stats.resident_count -= NBPDR / PAGE_SIZE;
                pmap_invalidate_all(kernel_pmap);
        }

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


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

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

void pmap_lazyfix_action(void);

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

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

static void
pmap_lazyfix_self(u_int mymask)
{

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


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

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

#else   /* SMP */

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

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

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

        KASSERT(pmap->pm_stats.resident_count == 0,
            ("pmap_release: pmap resident count %ld != 0",
            pmap->pm_stats.resident_count));

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

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

        bzero(pmap->pm_pdir + PTDPTDI, (nkpt + NPGPTD) *
            sizeof(*pmap->pm_pdir));
#ifdef SMP
        pmap->pm_pdir[MPPTDI] = 0;
#endif

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

        vm_page_lock_queues();
        for (i = 0; i < NPGPTD; i++) {
                m = ptdpg[i];
#ifdef PAE
                KASSERT(VM_PAGE_TO_PHYS(m) == (pmap->pm_pdpt[i] & PG_FRAME),
                    ("pmap_release: got wrong ptd page"));
#endif
                m->wire_count--;
                atomic_subtract_int(&cnt.v_wire_count, 1);
                vm_page_free_zero(m);
        }
        vm_page_unlock_queues();
        PMAP_LOCK_DESTROY(pmap);
}
\f
static int
kvm_size(SYSCTL_HANDLER_ARGS)
{
        unsigned long ksize = VM_MAX_KERNEL_ADDRESS - KERNBASE;

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

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

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

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

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

                /*
                 * This index is bogus, but out of the way
                 */
                nkpg = vm_page_alloc(NULL, nkpt,
                    VM_ALLOC_NOOBJ | VM_ALLOC_SYSTEM | VM_ALLOC_WIRED);
                if (!nkpg)
                        panic("pmap_growkernel: no memory to grow kernel");

                nkpt++;

                pmap_zero_page(nkpg);
                ptppaddr = VM_PAGE_TO_PHYS(nkpg);
                newpdir = (pd_entry_t) (ptppaddr | PG_V | PG_RW | PG_A | PG_M);
                pdir_pde(PTD, kernel_vm_end) = newpdir;

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


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

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

static __inline struct pv_chunk *
pv_to_chunk(pv_entry_t pv)
{

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

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

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

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

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

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

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

static long pv_entry_frees, pv_entry_allocs;
static int pv_entry_spare;

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

static int pmap_collect_inactive, pmap_collect_active;

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

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

        sched_pin();
        TAILQ_FOREACH(m, &vpq->pl, pageq) {
                if (m->hold_count || m->busy || (m->flags & PG_BUSY))
                        continue;
                TAILQ_FOREACH_SAFE(pv, &m->md.pv_list, pv_list, next_pv) {
                        va = pv->pv_va;
                        pmap = PV_PMAP(pv);
                        /* Avoid deadlock and lock recursion. */
                        if (pmap > locked_pmap)
                                PMAP_LOCK(pmap);
                        else if (pmap != locked_pmap && !PMAP_TRYLOCK(pmap))
                                continue;
                        pmap->pm_stats.resident_count--;
                        pte = pmap_pte_quick(pmap, va);
                        tpte = pte_load_clear(pte);
                        KASSERT((tpte & PG_W) == 0,
                            ("pmap_collect: wired pte %#jx", (uintmax_t)tpte));
                        if (tpte & PG_A)
                                vm_page_flag_set(m, PG_REFERENCED);
                        if (tpte & PG_M) {
                                KASSERT((tpte & PG_RW),
        ("pmap_collect: modified page not writable: va: %#x, pte: %#jx",
                                    va, (uintmax_t)tpte));
                                vm_page_dirty(m);
                        }
                        pmap_invalidate_page(pmap, va);
                        TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
                        if (TAILQ_EMPTY(&m->md.pv_list))
                                vm_page_flag_clear(m, PG_WRITEABLE);
                        m->md.pv_list_count--;
                        pmap_unuse_pt(pmap, va);
                        free_pv_entry(pmap, pv);
                        if (pmap != locked_pmap)
                                PMAP_UNLOCK(pmap);
                }
        }
        sched_unpin();
}


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

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

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

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

static void
pmap_remove_entry(pmap_t pmap, vm_page_t m, vm_offset_t va)
{
        pv_entry_t pv;

        PMAP_LOCK_ASSERT(pmap, MA_OWNED);
        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                if (pmap == PV_PMAP(pv) && va == pv->pv_va)
                        break;
        }
        KASSERT(pv != NULL, ("pmap_remove_entry: pv not found"));
        TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
        m->md.pv_list_count--;
        if (TAILQ_EMPTY(&m->md.pv_list))
                vm_page_flag_clear(m, PG_WRITEABLE);
        free_pv_entry(pmap, pv);
}

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

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

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

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

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

        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        PMAP_LOCK_ASSERT(pmap, MA_OWNED);
        oldpte = pte_load_clear(ptq);
        if (oldpte & PG_W)
                pmap->pm_stats.wired_count -= 1;
        /*
         * Machines that don't support invlpg, also don't support
         * PG_G.
         */
        if (oldpte & PG_G)
                pmap_invalidate_page(kernel_pmap, va);
        pmap->pm_stats.resident_count -= 1;
        if (oldpte & PG_MANAGED) {
                m = PHYS_TO_VM_PAGE(oldpte);
                if (oldpte & PG_M) {
                        KASSERT((oldpte & PG_RW),
        ("pmap_remove_pte: modified page not writable: va: %#x, pte: %#jx",
                            va, (uintmax_t)oldpte));
                        vm_page_dirty(m);
                }
                if (oldpte & PG_A)
                        vm_page_flag_set(m, PG_REFERENCED);
                pmap_remove_entry(pmap, m, va);
        }
        return (pmap_unuse_pt(pmap, va));
}

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

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

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

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

        anyvalid = 0;

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

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

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

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

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

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

                /*
                 * Check for large page.
                 */
                if ((ptpaddr & PG_PS) != 0) {
                        pmap->pm_pdir[pdirindex] = 0;
                        pmap->pm_stats.resident_count -= NBPDR / PAGE_SIZE;
                        anyvalid = 1;
                        continue;
                }

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

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

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

/*
 *      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 *pte, tpte;

#if defined(PMAP_DIAGNOSTIC)
        /*
         * XXX This makes pmap_remove_all() illegal for non-managed pages!
         */
        if (m->flags & PG_FICTITIOUS) {
                panic("pmap_remove_all: illegal for unmanaged page, va: 0x%x",
                    VM_PAGE_TO_PHYS(m));
        }
#endif
        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        sched_pin();
        while ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
                pmap = PV_PMAP(pv);
                PMAP_LOCK(pmap);
                pmap->pm_stats.resident_count--;
                pte = pmap_pte_quick(pmap, pv->pv_va);
                tpte = pte_load_clear(pte);
                if (tpte & PG_W)
                        pmap->pm_stats.wired_count--;
                if (tpte & PG_A)
                        vm_page_flag_set(m, PG_REFERENCED);

                /*
                 * Update the vm_page_t clean and reference bits.
                 */
                if (tpte & PG_M) {
                        KASSERT((tpte & PG_RW),
        ("pmap_remove_all: modified page not writable: va: %#x, pte: %#jx",
                            pv->pv_va, (uintmax_t)tpte));
                        vm_page_dirty(m);
                }
                pmap_invalidate_page(pmap, pv->pv_va);
                TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
                m->md.pv_list_count--;
                pmap_unuse_pt(pmap, pv->pv_va);
                free_pv_entry(pmap, pv);
                PMAP_UNLOCK(pmap);
        }
        vm_page_flag_clear(m, PG_WRITEABLE);
        sched_unpin();
}

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

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

        if (prot & VM_PROT_WRITE)
                return;

        anychanged = 0;

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

                pdnxt = (sva + NBPDR) & ~PDRMASK;

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

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

                /*
                 * Check for large page.
                 */
                if ((ptpaddr & PG_PS) != 0) {
                        pmap->pm_pdir[pdirindex] &= ~(PG_M|PG_RW);
                        anychanged = 1;
                        continue;
                }

                if (pdnxt > eva)
                        pdnxt = eva;

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

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

                        pbits &= ~(PG_RW | PG_M);

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

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

        va &= PG_FRAME;
#ifdef PMAP_DIAGNOSTIC
        if (va > VM_MAX_KERNEL_ADDRESS)
                panic("pmap_enter: toobig");
        if ((va >= UPT_MIN_ADDRESS) && (va < UPT_MAX_ADDRESS))
                panic("pmap_enter: invalid to pmap_enter page table pages (va: 0x%x)", va);
#endif

        mpte = NULL;

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

        /*
         * In the case that a page table page is not
         * resident, we are creating it here.
         */
        if (va < VM_MAXUSER_ADDRESS) {
                mpte = pmap_allocpte(pmap, va, M_WAITOK);
        }
#if 0 && defined(PMAP_DIAGNOSTIC)
        else {
                pd_entry_t *pdeaddr = pmap_pde(pmap, va);
                origpte = *pdeaddr;
                if ((origpte & PG_V) == 0) { 
                        panic("pmap_enter: invalid kernel page table page, pdir=%p, pde=%p, va=%p\n",
                                pmap->pm_pdir[PTDPTDI], origpte, va);
                }
        }
#endif

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

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

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

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

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

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

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

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

validate:
        /*
         * Now validate mapping with desired protection/wiring.
         */
        newpte = (pt_entry_t)(pa | PG_V);
        if ((prot & VM_PROT_WRITE) != 0)
                newpte |= PG_RW;
        if (wired)
                newpte |= PG_W;
        if (va < VM_MAXUSER_ADDRESS)
                newpte |= PG_U;
        if (pmap == kernel_pmap)
                newpte |= pgeflag;

        /*
         * if the mapping or permission bits are different, we need
         * to update the pte.
         */
        if ((origpte & ~(PG_M|PG_A)) != newpte) {
                if (origpte & PG_V) {
                        invlva = FALSE;
                        origpte = pte_load_store(pte, newpte | PG_A);
                        if (origpte & PG_A) {
                                if (origpte & PG_MANAGED)
                                        vm_page_flag_set(om, PG_REFERENCED);
                                if (opa != VM_PAGE_TO_PHYS(m))
                                        invlva = TRUE;
                        }
                        if (origpte & PG_M) {
                                KASSERT((origpte & PG_RW),
        ("pmap_enter: modified page not writable: va: %#x, pte: %#jx",
                                    va, (uintmax_t)origpte));
                                if ((origpte & PG_MANAGED) != 0)
                                        vm_page_dirty(om);
                                if ((prot & VM_PROT_WRITE) == 0)
                                        invlva = TRUE;
                        }
                        if (invlva)
                                pmap_invalidate_page(pmap, va);
                } else
                        pte_store(pte, newpte | PG_A);
        }
        sched_unpin();
        vm_page_unlock_queues();
        PMAP_UNLOCK(pmap);
}

/*
 * 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, mpte;
        vm_pindex_t diff, psize;

        VM_OBJECT_LOCK_ASSERT(m_start->object, MA_OWNED);
        psize = atop(end - start);
        mpte = NULL;
        m = m_start;
        PMAP_LOCK(pmap);
        while (m != NULL && (diff = m->pindex - m_start->pindex) < psize) {
                mpte = pmap_enter_quick_locked(pmap, start + ptoa(diff), m,
                    prot, mpte);
                m = TAILQ_NEXT(m, listq);
        }
        PMAP_UNLOCK(pmap);
}

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

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

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

static vm_page_t
pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
    vm_prot_t prot, vm_page_t mpte)
{
        pt_entry_t *pte;
        vm_paddr_t pa;

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

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

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

                        /*
                         * If the page table page is mapped, we just increment
                         * the hold count, and activate it.
                         */
                        if (ptepa) {
                                if (ptepa & PG_PS)
                                        panic("pmap_enter_quick: unexpected mapping into 4MB page");
                                mpte = PHYS_TO_VM_PAGE(ptepa);
                                mpte->wire_count++;
                        } else {
                                mpte = _pmap_allocpte(pmap, ptepindex,
                                    M_NOWAIT);
                                if (mpte == NULL)
                                        return (mpte);
                        }
                }
        } else {
                mpte = NULL;
        }

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

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

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

        pa = VM_PAGE_TO_PHYS(m);

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

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

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

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

        VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
        KASSERT(object->type == OBJT_DEVICE,
            ("pmap_object_init_pt: non-device object"));
        if (pseflag && 
            ((addr & (NBPDR - 1)) == 0) && ((size & (NBPDR - 1)) == 0)) {
                int i;
                vm_page_t m[1];
                unsigned int ptepindex;
                int npdes;
                pd_entry_t ptepa;

                PMAP_LOCK(pmap);
                if (pmap->pm_pdir[ptepindex = (addr >> PDRSHIFT)])
                        goto out;
                PMAP_UNLOCK(pmap);
retry:
                p = vm_page_lookup(object, pindex);
                if (p != NULL) {
                        if (vm_page_sleep_if_busy(p, FALSE, "init4p"))
                                goto retry;
                } else {
                        p = vm_page_alloc(object, pindex, VM_ALLOC_NORMAL);
                        if (p == NULL)
                                return;
                        m[0] = p;

                        if (vm_pager_get_pages(object, m, 1, 0) != VM_PAGER_OK) {
                                vm_page_lock_queues();
                                vm_page_free(p);
                                vm_page_unlock_queues();
                                return;
                        }

                        p = vm_page_lookup(object, pindex);
                        vm_page_lock_queues();
                        vm_page_wakeup(p);
                        vm_page_unlock_queues();
                }

                ptepa = VM_PAGE_TO_PHYS(p);
                if (ptepa & (NBPDR - 1))
                        return;

                p->valid = VM_PAGE_BITS_ALL;

                PMAP_LOCK(pmap);
                pmap->pm_stats.resident_count += size >> PAGE_SHIFT;
                npdes = size >> PDRSHIFT;
                for(i = 0; i < npdes; i++) {
                        pde_store(&pmap->pm_pdir[ptepindex],
                            ptepa | PG_U | PG_RW | PG_V | PG_PS);
                        ptepa += NBPDR;
                        ptepindex += 1;
                }
                pmap_invalidate_all(pmap);
out:
                PMAP_UNLOCK(pmap);
        }
}

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

        PMAP_LOCK(pmap);
        pte = pmap_pte(pmap, va);

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

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



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

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

        if (dst_addr != src_addr)
                return;

        if (!pmap_is_current(src_pmap))
                return;

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

                if (addr >= UPT_MIN_ADDRESS)
                        panic("pmap_copy: invalid to pmap_copy page tables");

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

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

                srcmpte = PHYS_TO_VM_PAGE(srcptepaddr);
                if (srcmpte->wire_count == 0)
                        panic("pmap_copy: source page table page is unused");

                if (pdnxt > end_addr)
                        pdnxt = end_addr;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

                                pte = vtopte(pv->pv_va);
                                tpte = *pte;

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

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

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

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

                                pmap->pm_stats.resident_count--;

                                pte_clear(pte);

                                /*
                                 * Update the vm_page_t clean/reference bits.
                                 */
                                if (tpte & PG_M)
                                        vm_page_dirty(m);

                                /* Mark free */
                                PV_STAT(pv_entry_frees++);
                                PV_STAT(pv_entry_spare++);
                                pv_entry_count--;
                                pc->pc_map[field] |= bitmask;
                                m->md.pv_list_count--;
                                TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
                                if (TAILQ_EMPTY(&m->md.pv_list))
                                        vm_page_flag_clear(m, PG_WRITEABLE);

                                pmap_unuse_pt(pmap, pv->pv_va);
                        }
                }
                if (allfree) {
                        PV_STAT(pv_entry_spare -= _NPCPV);
                        PV_STAT(pc_chunk_count--);
                        PV_STAT(pc_chunk_frees++);
                        TAILQ_REMOVE(&pmap->pm_pvchunk, pc, pc_list);
                        m = PHYS_TO_VM_PAGE(pmap_kextract((vm_offset_t)pc));
                        pmap_qremove((vm_offset_t)pc, 1);
                        vm_page_unwire(m, 0);
                        vm_page_free(m);
                        pmap_ptelist_free(&pv_vafree, (vm_offset_t)pc);
                }
        }
        sched_unpin();
        vm_page_unlock_queues();
        pmap_invalidate_all(pmap);
        PMAP_UNLOCK(pmap);
}

/*
 *      pmap_is_modified:
 *
 *      Return whether or not the specified physical page was modified
 *      in any physical maps.
 */
boolean_t
pmap_is_modified(vm_page_t m)
{
        pv_entry_t pv;
        pt_entry_t *pte;
        pmap_t pmap;
        boolean_t rv;

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

        sched_pin();
        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                pmap = PV_PMAP(pv);
                PMAP_LOCK(pmap);
                pte = pmap_pte_quick(pmap, pv->pv_va);
                rv = (*pte & PG_M) != 0;
                PMAP_UNLOCK(pmap);
                if (rv)
                        break;
        }
        sched_unpin();
        return (rv);
}

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

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

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

        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        if ((m->flags & PG_FICTITIOUS) != 0 ||
            (m->flags & PG_WRITEABLE) == 0)
                return;
        sched_pin();
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                pmap = PV_PMAP(pv);
                PMAP_LOCK(pmap);
                pte = pmap_pte_quick(pmap, pv->pv_va);
retry:
                oldpte = *pte;
                if ((oldpte & PG_RW) != 0) {
                        /*
                         * Regardless of whether a pte is 32 or 64 bits
                         * in size, PG_RW and PG_M are among the least
                         * significant 32 bits.
                         */
                        if (!atomic_cmpset_int((u_int *)pte, oldpte,
                            oldpte & ~(PG_RW | PG_M)))
                                goto retry;
                        if ((oldpte & PG_M) != 0)
                                vm_page_dirty(m);
                        pmap_invalidate_page(pmap, pv->pv_va);
                }
                PMAP_UNLOCK(pmap);
        }
        vm_page_flag_clear(m, PG_WRITEABLE);
        sched_unpin();
}

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

        if (m->flags & PG_FICTITIOUS)
                return (rtval);
        sched_pin();
        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        if ((pv = TAILQ_FIRST(&m->md.pv_list)) != NULL) {
                pvf = pv;
                do {
                        pvn = TAILQ_NEXT(pv, pv_list);
                        TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
                        TAILQ_INSERT_TAIL(&m->md.pv_list, pv, pv_list);
                        pmap = PV_PMAP(pv);
                        PMAP_LOCK(pmap);
                        pte = pmap_pte_quick(pmap, pv->pv_va);
                        if ((*pte & PG_A) != 0) {
                                atomic_clear_int((u_int *)pte, PG_A);
                                pmap_invalidate_page(pmap, pv->pv_va);
                                rtval++;
                                if (rtval > 4)
                                        pvn = NULL;
                        }
                        PMAP_UNLOCK(pmap);
                } while ((pv = pvn) != NULL && pv != pvf);
        }
        sched_unpin();
        return (rtval);
}

/*
 *      Clear the modify bits on the specified physical page.
 */
void
pmap_clear_modify(vm_page_t m)
{
        pv_entry_t pv;
        pmap_t pmap;
        pt_entry_t *pte;

        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        if ((m->flags & PG_FICTITIOUS) != 0)
                return;
        sched_pin();
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                pmap = PV_PMAP(pv);
                PMAP_LOCK(pmap);
                pte = pmap_pte_quick(pmap, pv->pv_va);
                if ((*pte & PG_M) != 0) {
                        /*
                         * Regardless of whether a pte is 32 or 64 bits
                         * in size, PG_M is among the least significant
                         * 32 bits. 
                         */
                        atomic_clear_int((u_int *)pte, PG_M);
                        pmap_invalidate_page(pmap, pv->pv_va);
                }
                PMAP_UNLOCK(pmap);
        }
        sched_unpin();
}

/*
 *      pmap_clear_reference:
 *
 *      Clear the reference bit on the specified physical page.
 */
void
pmap_clear_reference(vm_page_t m)
{
        pv_entry_t pv;
        pmap_t pmap;
        pt_entry_t *pte;

        mtx_assert(&vm_page_queue_mtx, MA_OWNED);
        if ((m->flags & PG_FICTITIOUS) != 0)
                return;
        sched_pin();
        TAILQ_FOREACH(pv, &m->md.pv_list, pv_list) {
                pmap = PV_PMAP(pv);
                PMAP_LOCK(pmap);
                pte = pmap_pte_quick(pmap, pv->pv_va);
                if ((*pte & PG_A) != 0) {
                        /*
                         * Regardless of whether a pte is 32 or 64 bits
                         * in size, PG_A is among the least significant
                         * 32 bits. 
                         */
                        atomic_clear_int((u_int *)pte, PG_A);
                        pmap_invalidate_page(pmap, pv->pv_va);
                }
                PMAP_UNLOCK(pmap);
        }
        sched_unpin();
}

/*
 * Miscellaneous support routines follow
 */

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

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

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

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

void *
pmap_mapdev(vm_paddr_t pa, vm_size_t size)
{

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

void *
pmap_mapbios(vm_paddr_t pa, vm_size_t size)
{

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

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

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

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

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

        /* Only supported on kernel virtual addresses. */
        if (base <= VM_MAXUSER_ADDRESS)
                return (EINVAL);

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

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

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

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

/*
 * perform the pmap work for mincore
 */
int
pmap_mincore(pmap_t pmap, vm_offset_t addr)
{
        pt_entry_t *ptep, pte;
        vm_page_t m;
        int val = 0;
        
        PMAP_LOCK(pmap);
        ptep = pmap_pte(pmap, addr);
        pte = (ptep != NULL) ? *ptep : 0;
        pmap_pte_release(ptep);
        PMAP_UNLOCK(pmap);

        if (pte != 0) {
                vm_paddr_t pa;

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

                pa = pte & PG_FRAME;

                m = PHYS_TO_VM_PAGE(pa);

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

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

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

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

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

        addr = (addr + PDRMASK) & ~PDRMASK;
        return addr;
}


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

        sx_slock(&allproc_lock);
        LIST_FOREACH(p, &allproc, p_list) {
                if (p->p_pid != pid)
                        continue;

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

#if defined(DEBUG)

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

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

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

}

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

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