vm_object.c: minor style

[FreeBSD/FreeBSD.git] / sys / vm / vm_phys.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2002-2006 Rice University
 * Copyright (c) 2007 Alan L. Cox <alc@cs.rice.edu>
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by Alan L. Cox,
 * Olivier Crameri, Peter Druschel, Sitaram Iyer, and Juan Navarro.
 *
 * 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 COPYRIGHT HOLDERS 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 COPYRIGHT
 * HOLDERS 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.
 */

/*
 *      Physical memory system implementation
 *
 * Any external functions defined by this module are only to be used by the
 * virtual memory system.
 */

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

#include "opt_ddb.h"
#include "opt_vm.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/domainset.h>
#include <sys/lock.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/rwlock.h>
#include <sys/sbuf.h>
#include <sys/sysctl.h>
#include <sys/tree.h>
#include <sys/vmmeter.h>

#include <ddb/ddb.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_object.h>
#include <vm/vm_page.h>
#include <vm/vm_phys.h>
#include <vm/vm_pagequeue.h>

_Static_assert(sizeof(long) * NBBY >= VM_PHYSSEG_MAX,
    "Too many physsegs.");

#ifdef NUMA
struct mem_affinity __read_mostly *mem_affinity;
int __read_mostly *mem_locality;
#endif

int __read_mostly vm_ndomains = 1;
domainset_t __read_mostly all_domains = DOMAINSET_T_INITIALIZER(0x1);

struct vm_phys_seg __read_mostly vm_phys_segs[VM_PHYSSEG_MAX];
int __read_mostly vm_phys_nsegs;
static struct vm_phys_seg vm_phys_early_segs[8];
static int vm_phys_early_nsegs;

struct vm_phys_fictitious_seg;
static int vm_phys_fictitious_cmp(struct vm_phys_fictitious_seg *,
    struct vm_phys_fictitious_seg *);

RB_HEAD(fict_tree, vm_phys_fictitious_seg) vm_phys_fictitious_tree =
    RB_INITIALIZER(&vm_phys_fictitious_tree);

struct vm_phys_fictitious_seg {
        RB_ENTRY(vm_phys_fictitious_seg) node;
        /* Memory region data */
        vm_paddr_t      start;
        vm_paddr_t      end;
        vm_page_t       first_page;
};

RB_GENERATE_STATIC(fict_tree, vm_phys_fictitious_seg, node,
    vm_phys_fictitious_cmp);

static struct rwlock_padalign vm_phys_fictitious_reg_lock;
MALLOC_DEFINE(M_FICT_PAGES, "vm_fictitious", "Fictitious VM pages");

static struct vm_freelist __aligned(CACHE_LINE_SIZE)
    vm_phys_free_queues[MAXMEMDOM][VM_NFREELIST][VM_NFREEPOOL]
    [VM_NFREEORDER_MAX];

static int __read_mostly vm_nfreelists;

/*
 * These "avail lists" are globals used to communicate boot-time physical
 * memory layout to other parts of the kernel.  Each physically contiguous
 * region of memory is defined by a start address at an even index and an
 * end address at the following odd index.  Each list is terminated by a
 * pair of zero entries.
 *
 * dump_avail tells the dump code what regions to include in a crash dump, and
 * phys_avail is all of the remaining physical memory that is available for
 * the vm system.
 *
 * Initially dump_avail and phys_avail are identical.  Boot time memory
 * allocations remove extents from phys_avail that may still be included
 * in dumps.
 */
vm_paddr_t phys_avail[PHYS_AVAIL_COUNT];
vm_paddr_t dump_avail[PHYS_AVAIL_COUNT];

/*
 * Provides the mapping from VM_FREELIST_* to free list indices (flind).
 */
static int __read_mostly vm_freelist_to_flind[VM_NFREELIST];

CTASSERT(VM_FREELIST_DEFAULT == 0);

#ifdef VM_FREELIST_DMA32
#define VM_DMA32_BOUNDARY       ((vm_paddr_t)1 << 32)
#endif

/*
 * Enforce the assumptions made by vm_phys_add_seg() and vm_phys_init() about
 * the ordering of the free list boundaries.
 */
#if defined(VM_LOWMEM_BOUNDARY) && defined(VM_DMA32_BOUNDARY)
CTASSERT(VM_LOWMEM_BOUNDARY < VM_DMA32_BOUNDARY);
#endif

static int sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS);
SYSCTL_OID(_vm, OID_AUTO, phys_free,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
    sysctl_vm_phys_free, "A",
    "Phys Free Info");

static int sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS);
SYSCTL_OID(_vm, OID_AUTO, phys_segs,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
    sysctl_vm_phys_segs, "A",
    "Phys Seg Info");

#ifdef NUMA
static int sysctl_vm_phys_locality(SYSCTL_HANDLER_ARGS);
SYSCTL_OID(_vm, OID_AUTO, phys_locality,
    CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
    sysctl_vm_phys_locality, "A",
    "Phys Locality Info");
#endif

SYSCTL_INT(_vm, OID_AUTO, ndomains, CTLFLAG_RD,
    &vm_ndomains, 0, "Number of physical memory domains available.");

static vm_page_t vm_phys_alloc_seg_contig(struct vm_phys_seg *seg,
    u_long npages, vm_paddr_t low, vm_paddr_t high, u_long alignment,
    vm_paddr_t boundary);
static void _vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end, int domain);
static void vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end);
static void vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl,
    int order, int tail);

/*
 * Red-black tree helpers for vm fictitious range management.
 */
static inline int
vm_phys_fictitious_in_range(struct vm_phys_fictitious_seg *p,
    struct vm_phys_fictitious_seg *range)
{

        KASSERT(range->start != 0 && range->end != 0,
            ("Invalid range passed on search for vm_fictitious page"));
        if (p->start >= range->end)
                return (1);
        if (p->start < range->start)
                return (-1);

        return (0);
}

static int
vm_phys_fictitious_cmp(struct vm_phys_fictitious_seg *p1,
    struct vm_phys_fictitious_seg *p2)
{

        /* Check if this is a search for a page */
        if (p1->end == 0)
                return (vm_phys_fictitious_in_range(p1, p2));

        KASSERT(p2->end != 0,
    ("Invalid range passed as second parameter to vm fictitious comparison"));

        /* Searching to add a new range */
        if (p1->end <= p2->start)
                return (-1);
        if (p1->start >= p2->end)
                return (1);

        panic("Trying to add overlapping vm fictitious ranges:\n"
            "[%#jx:%#jx] and [%#jx:%#jx]", (uintmax_t)p1->start,
            (uintmax_t)p1->end, (uintmax_t)p2->start, (uintmax_t)p2->end);
}

int
vm_phys_domain_match(int prefer, vm_paddr_t low, vm_paddr_t high)
{
#ifdef NUMA
        domainset_t mask;
        int i;

        if (vm_ndomains == 1 || mem_affinity == NULL)
                return (0);

        DOMAINSET_ZERO(&mask);
        /*
         * Check for any memory that overlaps low, high.
         */
        for (i = 0; mem_affinity[i].end != 0; i++)
                if (mem_affinity[i].start <= high &&
                    mem_affinity[i].end >= low)
                        DOMAINSET_SET(mem_affinity[i].domain, &mask);
        if (prefer != -1 && DOMAINSET_ISSET(prefer, &mask))
                return (prefer);
        if (DOMAINSET_EMPTY(&mask))
                panic("vm_phys_domain_match:  Impossible constraint");
        return (DOMAINSET_FFS(&mask) - 1);
#else
        return (0);
#endif
}

/*
 * Outputs the state of the physical memory allocator, specifically,
 * the amount of physical memory in each free list.
 */
static int
sysctl_vm_phys_free(SYSCTL_HANDLER_ARGS)
{
        struct sbuf sbuf;
        struct vm_freelist *fl;
        int dom, error, flind, oind, pind;

        error = sysctl_wire_old_buffer(req, 0);
        if (error != 0)
                return (error);
        sbuf_new_for_sysctl(&sbuf, NULL, 128 * vm_ndomains, req);
        for (dom = 0; dom < vm_ndomains; dom++) {
                sbuf_printf(&sbuf,"\nDOMAIN %d:\n", dom);
                for (flind = 0; flind < vm_nfreelists; flind++) {
                        sbuf_printf(&sbuf, "\nFREE LIST %d:\n"
                            "\n  ORDER (SIZE)  |  NUMBER"
                            "\n              ", flind);
                        for (pind = 0; pind < VM_NFREEPOOL; pind++)
                                sbuf_printf(&sbuf, "  |  POOL %d", pind);
                        sbuf_printf(&sbuf, "\n--            ");
                        for (pind = 0; pind < VM_NFREEPOOL; pind++)
                                sbuf_printf(&sbuf, "-- --      ");
                        sbuf_printf(&sbuf, "--\n");
                        for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
                                sbuf_printf(&sbuf, "  %2d (%6dK)", oind,
                                    1 << (PAGE_SHIFT - 10 + oind));
                                for (pind = 0; pind < VM_NFREEPOOL; pind++) {
                                fl = vm_phys_free_queues[dom][flind][pind];
                                        sbuf_printf(&sbuf, "  |  %6d",
                                            fl[oind].lcnt);
                                }
                                sbuf_printf(&sbuf, "\n");
                        }
                }
        }
        error = sbuf_finish(&sbuf);
        sbuf_delete(&sbuf);
        return (error);
}

/*
 * Outputs the set of physical memory segments.
 */
static int
sysctl_vm_phys_segs(SYSCTL_HANDLER_ARGS)
{
        struct sbuf sbuf;
        struct vm_phys_seg *seg;
        int error, segind;

        error = sysctl_wire_old_buffer(req, 0);
        if (error != 0)
                return (error);
        sbuf_new_for_sysctl(&sbuf, NULL, 128, req);
        for (segind = 0; segind < vm_phys_nsegs; segind++) {
                sbuf_printf(&sbuf, "\nSEGMENT %d:\n\n", segind);
                seg = &vm_phys_segs[segind];
                sbuf_printf(&sbuf, "start:     %#jx\n",
                    (uintmax_t)seg->start);
                sbuf_printf(&sbuf, "end:       %#jx\n",
                    (uintmax_t)seg->end);
                sbuf_printf(&sbuf, "domain:    %d\n", seg->domain);
                sbuf_printf(&sbuf, "free list: %p\n", seg->free_queues);
        }
        error = sbuf_finish(&sbuf);
        sbuf_delete(&sbuf);
        return (error);
}

/*
 * Return affinity, or -1 if there's no affinity information.
 */
int
vm_phys_mem_affinity(int f, int t)
{

#ifdef NUMA
        if (mem_locality == NULL)
                return (-1);
        if (f >= vm_ndomains || t >= vm_ndomains)
                return (-1);
        return (mem_locality[f * vm_ndomains + t]);
#else
        return (-1);
#endif
}

#ifdef NUMA
/*
 * Outputs the VM locality table.
 */
static int
sysctl_vm_phys_locality(SYSCTL_HANDLER_ARGS)
{
        struct sbuf sbuf;
        int error, i, j;

        error = sysctl_wire_old_buffer(req, 0);
        if (error != 0)
                return (error);
        sbuf_new_for_sysctl(&sbuf, NULL, 128, req);

        sbuf_printf(&sbuf, "\n");

        for (i = 0; i < vm_ndomains; i++) {
                sbuf_printf(&sbuf, "%d: ", i);
                for (j = 0; j < vm_ndomains; j++) {
                        sbuf_printf(&sbuf, "%d ", vm_phys_mem_affinity(i, j));
                }
                sbuf_printf(&sbuf, "\n");
        }
        error = sbuf_finish(&sbuf);
        sbuf_delete(&sbuf);
        return (error);
}
#endif

static void
vm_freelist_add(struct vm_freelist *fl, vm_page_t m, int order, int tail)
{

        m->order = order;
        if (tail)
                TAILQ_INSERT_TAIL(&fl[order].pl, m, listq);
        else
                TAILQ_INSERT_HEAD(&fl[order].pl, m, listq);
        fl[order].lcnt++;
}

static void
vm_freelist_rem(struct vm_freelist *fl, vm_page_t m, int order)
{

        TAILQ_REMOVE(&fl[order].pl, m, listq);
        fl[order].lcnt--;
        m->order = VM_NFREEORDER;
}

/*
 * Create a physical memory segment.
 */
static void
_vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end, int domain)
{
        struct vm_phys_seg *seg;

        KASSERT(vm_phys_nsegs < VM_PHYSSEG_MAX,
            ("vm_phys_create_seg: increase VM_PHYSSEG_MAX"));
        KASSERT(domain >= 0 && domain < vm_ndomains,
            ("vm_phys_create_seg: invalid domain provided"));
        seg = &vm_phys_segs[vm_phys_nsegs++];
        while (seg > vm_phys_segs && (seg - 1)->start >= end) {
                *seg = *(seg - 1);
                seg--;
        }
        seg->start = start;
        seg->end = end;
        seg->domain = domain;
}

static void
vm_phys_create_seg(vm_paddr_t start, vm_paddr_t end)
{
#ifdef NUMA
        int i;

        if (mem_affinity == NULL) {
                _vm_phys_create_seg(start, end, 0);
                return;
        }

        for (i = 0;; i++) {
                if (mem_affinity[i].end == 0)
                        panic("Reached end of affinity info");
                if (mem_affinity[i].end <= start)
                        continue;
                if (mem_affinity[i].start > start)
                        panic("No affinity info for start %jx",
                            (uintmax_t)start);
                if (mem_affinity[i].end >= end) {
                        _vm_phys_create_seg(start, end,
                            mem_affinity[i].domain);
                        break;
                }
                _vm_phys_create_seg(start, mem_affinity[i].end,
                    mem_affinity[i].domain);
                start = mem_affinity[i].end;
        }
#else
        _vm_phys_create_seg(start, end, 0);
#endif
}

/*
 * Add a physical memory segment.
 */
void
vm_phys_add_seg(vm_paddr_t start, vm_paddr_t end)
{
        vm_paddr_t paddr;

        KASSERT((start & PAGE_MASK) == 0,
            ("vm_phys_define_seg: start is not page aligned"));
        KASSERT((end & PAGE_MASK) == 0,
            ("vm_phys_define_seg: end is not page aligned"));

        /*
         * Split the physical memory segment if it spans two or more free
         * list boundaries.
         */
        paddr = start;
#ifdef  VM_FREELIST_LOWMEM
        if (paddr < VM_LOWMEM_BOUNDARY && end > VM_LOWMEM_BOUNDARY) {
                vm_phys_create_seg(paddr, VM_LOWMEM_BOUNDARY);
                paddr = VM_LOWMEM_BOUNDARY;
        }
#endif
#ifdef  VM_FREELIST_DMA32
        if (paddr < VM_DMA32_BOUNDARY && end > VM_DMA32_BOUNDARY) {
                vm_phys_create_seg(paddr, VM_DMA32_BOUNDARY);
                paddr = VM_DMA32_BOUNDARY;
        }
#endif
        vm_phys_create_seg(paddr, end);
}

/*
 * Initialize the physical memory allocator.
 *
 * Requires that vm_page_array is initialized!
 */
void
vm_phys_init(void)
{
        struct vm_freelist *fl;
        struct vm_phys_seg *end_seg, *prev_seg, *seg, *tmp_seg;
        u_long npages;
        int dom, flind, freelist, oind, pind, segind;

        /*
         * Compute the number of free lists, and generate the mapping from the
         * manifest constants VM_FREELIST_* to the free list indices.
         *
         * Initially, the entries of vm_freelist_to_flind[] are set to either
         * 0 or 1 to indicate which free lists should be created.
         */
        npages = 0;
        for (segind = vm_phys_nsegs - 1; segind >= 0; segind--) {
                seg = &vm_phys_segs[segind];
#ifdef  VM_FREELIST_LOWMEM
                if (seg->end <= VM_LOWMEM_BOUNDARY)
                        vm_freelist_to_flind[VM_FREELIST_LOWMEM] = 1;
                else
#endif
#ifdef  VM_FREELIST_DMA32
                if (
#ifdef  VM_DMA32_NPAGES_THRESHOLD
                    /*
                     * Create the DMA32 free list only if the amount of
                     * physical memory above physical address 4G exceeds the
                     * given threshold.
                     */
                    npages > VM_DMA32_NPAGES_THRESHOLD &&
#endif
                    seg->end <= VM_DMA32_BOUNDARY)
                        vm_freelist_to_flind[VM_FREELIST_DMA32] = 1;
                else
#endif
                {
                        npages += atop(seg->end - seg->start);
                        vm_freelist_to_flind[VM_FREELIST_DEFAULT] = 1;
                }
        }
        /* Change each entry into a running total of the free lists. */
        for (freelist = 1; freelist < VM_NFREELIST; freelist++) {
                vm_freelist_to_flind[freelist] +=
                    vm_freelist_to_flind[freelist - 1];
        }
        vm_nfreelists = vm_freelist_to_flind[VM_NFREELIST - 1];
        KASSERT(vm_nfreelists > 0, ("vm_phys_init: no free lists"));
        /* Change each entry into a free list index. */
        for (freelist = 0; freelist < VM_NFREELIST; freelist++)
                vm_freelist_to_flind[freelist]--;

        /*
         * Initialize the first_page and free_queues fields of each physical
         * memory segment.
         */
#ifdef VM_PHYSSEG_SPARSE
        npages = 0;
#endif
        for (segind = 0; segind < vm_phys_nsegs; segind++) {
                seg = &vm_phys_segs[segind];
#ifdef VM_PHYSSEG_SPARSE
                seg->first_page = &vm_page_array[npages];
                npages += atop(seg->end - seg->start);
#else
                seg->first_page = PHYS_TO_VM_PAGE(seg->start);
#endif
#ifdef  VM_FREELIST_LOWMEM
                if (seg->end <= VM_LOWMEM_BOUNDARY) {
                        flind = vm_freelist_to_flind[VM_FREELIST_LOWMEM];
                        KASSERT(flind >= 0,
                            ("vm_phys_init: LOWMEM flind < 0"));
                } else
#endif
#ifdef  VM_FREELIST_DMA32
                if (seg->end <= VM_DMA32_BOUNDARY) {
                        flind = vm_freelist_to_flind[VM_FREELIST_DMA32];
                        KASSERT(flind >= 0,
                            ("vm_phys_init: DMA32 flind < 0"));
                } else
#endif
                {
                        flind = vm_freelist_to_flind[VM_FREELIST_DEFAULT];
                        KASSERT(flind >= 0,
                            ("vm_phys_init: DEFAULT flind < 0"));
                }
                seg->free_queues = &vm_phys_free_queues[seg->domain][flind];
        }

        /*
         * Coalesce physical memory segments that are contiguous and share the
         * same per-domain free queues.
         */
        prev_seg = vm_phys_segs;
        seg = &vm_phys_segs[1];
        end_seg = &vm_phys_segs[vm_phys_nsegs];
        while (seg < end_seg) {
                if (prev_seg->end == seg->start &&
                    prev_seg->free_queues == seg->free_queues) {
                        prev_seg->end = seg->end;
                        KASSERT(prev_seg->domain == seg->domain,
                            ("vm_phys_init: free queues cannot span domains"));
                        vm_phys_nsegs--;
                        end_seg--;
                        for (tmp_seg = seg; tmp_seg < end_seg; tmp_seg++)
                                *tmp_seg = *(tmp_seg + 1);
                } else {
                        prev_seg = seg;
                        seg++;
                }
        }

        /*
         * Initialize the free queues.
         */
        for (dom = 0; dom < vm_ndomains; dom++) {
                for (flind = 0; flind < vm_nfreelists; flind++) {
                        for (pind = 0; pind < VM_NFREEPOOL; pind++) {
                                fl = vm_phys_free_queues[dom][flind][pind];
                                for (oind = 0; oind < VM_NFREEORDER; oind++)
                                        TAILQ_INIT(&fl[oind].pl);
                        }
                }
        }

        rw_init(&vm_phys_fictitious_reg_lock, "vmfctr");
}

/*
 * Register info about the NUMA topology of the system.
 *
 * Invoked by platform-dependent code prior to vm_phys_init().
 */
void
vm_phys_register_domains(int ndomains, struct mem_affinity *affinity,
    int *locality)
{
#ifdef NUMA
        int d, i;

        /*
         * For now the only override value that we support is 1, which
         * effectively disables NUMA-awareness in the allocators.
         */
        d = 0;
        TUNABLE_INT_FETCH("vm.numa.disabled", &d);
        if (d)
                ndomains = 1;

        if (ndomains > 1) {
                vm_ndomains = ndomains;
                mem_affinity = affinity;
                mem_locality = locality;
        }

        for (i = 0; i < vm_ndomains; i++)
                DOMAINSET_SET(i, &all_domains);
#else
        (void)ndomains;
        (void)affinity;
        (void)locality;
#endif
}

/*
 * Split a contiguous, power of two-sized set of physical pages.
 *
 * When this function is called by a page allocation function, the caller
 * should request insertion at the head unless the order [order, oind) queues
 * are known to be empty.  The objective being to reduce the likelihood of
 * long-term fragmentation by promoting contemporaneous allocation and
 * (hopefully) deallocation.
 */
static __inline void
vm_phys_split_pages(vm_page_t m, int oind, struct vm_freelist *fl, int order,
    int tail)
{
        vm_page_t m_buddy;

        while (oind > order) {
                oind--;
                m_buddy = &m[1 << oind];
                KASSERT(m_buddy->order == VM_NFREEORDER,
                    ("vm_phys_split_pages: page %p has unexpected order %d",
                    m_buddy, m_buddy->order));
                vm_freelist_add(fl, m_buddy, oind, tail);
        }
}

/*
 * Add the physical pages [m, m + npages) at the end of a power-of-two aligned
 * and sized set to the specified free list.
 *
 * When this function is called by a page allocation function, the caller
 * should request insertion at the head unless the lower-order queues are
 * known to be empty.  The objective being to reduce the likelihood of long-
 * term fragmentation by promoting contemporaneous allocation and (hopefully)
 * deallocation.
 *
 * The physical page m's buddy must not be free.
 */
static void
vm_phys_enq_range(vm_page_t m, u_int npages, struct vm_freelist *fl, int tail)
{
        u_int n;
        int order;

        KASSERT(npages > 0, ("vm_phys_enq_range: npages is 0"));
        KASSERT(((VM_PAGE_TO_PHYS(m) + npages * PAGE_SIZE) &
            ((PAGE_SIZE << (fls(npages) - 1)) - 1)) == 0,
            ("vm_phys_enq_range: page %p and npages %u are misaligned",
            m, npages));
        do {
                KASSERT(m->order == VM_NFREEORDER,
                    ("vm_phys_enq_range: page %p has unexpected order %d",
                    m, m->order));
                order = ffs(npages) - 1;
                KASSERT(order < VM_NFREEORDER,
                    ("vm_phys_enq_range: order %d is out of range", order));
                vm_freelist_add(fl, m, order, tail);
                n = 1 << order;
                m += n;
                npages -= n;
        } while (npages > 0);
}

/*
 * Set the pool for a contiguous, power of two-sized set of physical pages. 
 */
static void
vm_phys_set_pool(int pool, vm_page_t m, int order)
{
        vm_page_t m_tmp;

        for (m_tmp = m; m_tmp < &m[1 << order]; m_tmp++)
                m_tmp->pool = pool;
}

/*
 * Tries to allocate the specified number of pages from the specified pool
 * within the specified domain.  Returns the actual number of allocated pages
 * and a pointer to each page through the array ma[].
 *
 * The returned pages may not be physically contiguous.  However, in contrast
 * to performing multiple, back-to-back calls to vm_phys_alloc_pages(..., 0),
 * calling this function once to allocate the desired number of pages will
 * avoid wasted time in vm_phys_split_pages().
 *
 * The free page queues for the specified domain must be locked.
 */
int
vm_phys_alloc_npages(int domain, int pool, int npages, vm_page_t ma[])
{
        struct vm_freelist *alt, *fl;
        vm_page_t m;
        int avail, end, flind, freelist, i, need, oind, pind;

        KASSERT(domain >= 0 && domain < vm_ndomains,
            ("vm_phys_alloc_npages: domain %d is out of range", domain));
        KASSERT(pool < VM_NFREEPOOL,
            ("vm_phys_alloc_npages: pool %d is out of range", pool));
        KASSERT(npages <= 1 << (VM_NFREEORDER - 1),
            ("vm_phys_alloc_npages: npages %d is out of range", npages));
        vm_domain_free_assert_locked(VM_DOMAIN(domain));
        i = 0;
        for (freelist = 0; freelist < VM_NFREELIST; freelist++) {
                flind = vm_freelist_to_flind[freelist];
                if (flind < 0)
                        continue;
                fl = vm_phys_free_queues[domain][flind][pool];
                for (oind = 0; oind < VM_NFREEORDER; oind++) {
                        while ((m = TAILQ_FIRST(&fl[oind].pl)) != NULL) {
                                vm_freelist_rem(fl, m, oind);
                                avail = 1 << oind;
                                need = imin(npages - i, avail);
                                for (end = i + need; i < end;)
                                        ma[i++] = m++;
                                if (need < avail) {
                                        /*
                                         * Return excess pages to fl.  Its
                                         * order [0, oind) queues are empty.
                                         */
                                        vm_phys_enq_range(m, avail - need, fl,
                                            1);
                                        return (npages);
                                } else if (i == npages)
                                        return (npages);
                        }
                }
                for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
                        for (pind = 0; pind < VM_NFREEPOOL; pind++) {
                                alt = vm_phys_free_queues[domain][flind][pind];
                                while ((m = TAILQ_FIRST(&alt[oind].pl)) !=
                                    NULL) {
                                        vm_freelist_rem(alt, m, oind);
                                        vm_phys_set_pool(pool, m, oind);
                                        avail = 1 << oind;
                                        need = imin(npages - i, avail);
                                        for (end = i + need; i < end;)
                                                ma[i++] = m++;
                                        if (need < avail) {
                                                /*
                                                 * Return excess pages to fl.
                                                 * Its order [0, oind) queues
                                                 * are empty.
                                                 */
                                                vm_phys_enq_range(m, avail -
                                                    need, fl, 1);
                                                return (npages);
                                        } else if (i == npages)
                                                return (npages);
                                }
                        }
                }
        }
        return (i);
}

/*
 * Allocate a contiguous, power of two-sized set of physical pages
 * from the free lists.
 *
 * The free page queues must be locked.
 */
vm_page_t
vm_phys_alloc_pages(int domain, int pool, int order)
{
        vm_page_t m;
        int freelist;

        for (freelist = 0; freelist < VM_NFREELIST; freelist++) {
                m = vm_phys_alloc_freelist_pages(domain, freelist, pool, order);
                if (m != NULL)
                        return (m);
        }
        return (NULL);
}

/*
 * Allocate a contiguous, power of two-sized set of physical pages from the
 * specified free list.  The free list must be specified using one of the
 * manifest constants VM_FREELIST_*.
 *
 * The free page queues must be locked.
 */
vm_page_t
vm_phys_alloc_freelist_pages(int domain, int freelist, int pool, int order)
{
        struct vm_freelist *alt, *fl;
        vm_page_t m;
        int oind, pind, flind;

        KASSERT(domain >= 0 && domain < vm_ndomains,
            ("vm_phys_alloc_freelist_pages: domain %d is out of range",
            domain));
        KASSERT(freelist < VM_NFREELIST,
            ("vm_phys_alloc_freelist_pages: freelist %d is out of range",
            freelist));
        KASSERT(pool < VM_NFREEPOOL,
            ("vm_phys_alloc_freelist_pages: pool %d is out of range", pool));
        KASSERT(order < VM_NFREEORDER,
            ("vm_phys_alloc_freelist_pages: order %d is out of range", order));

        flind = vm_freelist_to_flind[freelist];
        /* Check if freelist is present */
        if (flind < 0)
                return (NULL);

        vm_domain_free_assert_locked(VM_DOMAIN(domain));
        fl = &vm_phys_free_queues[domain][flind][pool][0];
        for (oind = order; oind < VM_NFREEORDER; oind++) {
                m = TAILQ_FIRST(&fl[oind].pl);
                if (m != NULL) {
                        vm_freelist_rem(fl, m, oind);
                        /* The order [order, oind) queues are empty. */
                        vm_phys_split_pages(m, oind, fl, order, 1);
                        return (m);
                }
        }

        /*
         * The given pool was empty.  Find the largest
         * contiguous, power-of-two-sized set of pages in any
         * pool.  Transfer these pages to the given pool, and
         * use them to satisfy the allocation.
         */
        for (oind = VM_NFREEORDER - 1; oind >= order; oind--) {
                for (pind = 0; pind < VM_NFREEPOOL; pind++) {
                        alt = &vm_phys_free_queues[domain][flind][pind][0];
                        m = TAILQ_FIRST(&alt[oind].pl);
                        if (m != NULL) {
                                vm_freelist_rem(alt, m, oind);
                                vm_phys_set_pool(pool, m, oind);
                                /* The order [order, oind) queues are empty. */
                                vm_phys_split_pages(m, oind, fl, order, 1);
                                return (m);
                        }
                }
        }
        return (NULL);
}

/*
 * Find the vm_page corresponding to the given physical address.
 */
vm_page_t
vm_phys_paddr_to_vm_page(vm_paddr_t pa)
{
        struct vm_phys_seg *seg;
        int segind;

        for (segind = 0; segind < vm_phys_nsegs; segind++) {
                seg = &vm_phys_segs[segind];
                if (pa >= seg->start && pa < seg->end)
                        return (&seg->first_page[atop(pa - seg->start)]);
        }
        return (NULL);
}

vm_page_t
vm_phys_fictitious_to_vm_page(vm_paddr_t pa)
{
        struct vm_phys_fictitious_seg tmp, *seg;
        vm_page_t m;

        m = NULL;
        tmp.start = pa;
        tmp.end = 0;

        rw_rlock(&vm_phys_fictitious_reg_lock);
        seg = RB_FIND(fict_tree, &vm_phys_fictitious_tree, &tmp);
        rw_runlock(&vm_phys_fictitious_reg_lock);
        if (seg == NULL)
                return (NULL);

        m = &seg->first_page[atop(pa - seg->start)];
        KASSERT((m->flags & PG_FICTITIOUS) != 0, ("%p not fictitious", m));

        return (m);
}

static inline void
vm_phys_fictitious_init_range(vm_page_t range, vm_paddr_t start,
    long page_count, vm_memattr_t memattr)
{
        long i;

        bzero(range, page_count * sizeof(*range));
        for (i = 0; i < page_count; i++) {
                vm_page_initfake(&range[i], start + PAGE_SIZE * i, memattr);
                range[i].oflags &= ~VPO_UNMANAGED;
                range[i].busy_lock = VPB_UNBUSIED;
        }
}

int
vm_phys_fictitious_reg_range(vm_paddr_t start, vm_paddr_t end,
    vm_memattr_t memattr)
{
        struct vm_phys_fictitious_seg *seg;
        vm_page_t fp;
        long page_count;
#ifdef VM_PHYSSEG_DENSE
        long pi, pe;
        long dpage_count;
#endif

        KASSERT(start < end,
            ("Start of segment isn't less than end (start: %jx end: %jx)",
            (uintmax_t)start, (uintmax_t)end));

        page_count = (end - start) / PAGE_SIZE;

#ifdef VM_PHYSSEG_DENSE
        pi = atop(start);
        pe = atop(end);
        if (pi >= first_page && (pi - first_page) < vm_page_array_size) {
                fp = &vm_page_array[pi - first_page];
                if ((pe - first_page) > vm_page_array_size) {
                        /*
                         * We have a segment that starts inside
                         * of vm_page_array, but ends outside of it.
                         *
                         * Use vm_page_array pages for those that are
                         * inside of the vm_page_array range, and
                         * allocate the remaining ones.
                         */
                        dpage_count = vm_page_array_size - (pi - first_page);
                        vm_phys_fictitious_init_range(fp, start, dpage_count,
                            memattr);
                        page_count -= dpage_count;
                        start += ptoa(dpage_count);
                        goto alloc;
                }
                /*
                 * We can allocate the full range from vm_page_array,
                 * so there's no need to register the range in the tree.
                 */
                vm_phys_fictitious_init_range(fp, start, page_count, memattr);
                return (0);
        } else if (pe > first_page && (pe - first_page) < vm_page_array_size) {
                /*
                 * We have a segment that ends inside of vm_page_array,
                 * but starts outside of it.
                 */
                fp = &vm_page_array[0];
                dpage_count = pe - first_page;
                vm_phys_fictitious_init_range(fp, ptoa(first_page), dpage_count,
                    memattr);
                end -= ptoa(dpage_count);
                page_count -= dpage_count;
                goto alloc;
        } else if (pi < first_page && pe > (first_page + vm_page_array_size)) {
                /*
                 * Trying to register a fictitious range that expands before
                 * and after vm_page_array.
                 */
                return (EINVAL);
        } else {
alloc:
#endif
                fp = malloc(page_count * sizeof(struct vm_page), M_FICT_PAGES,
                    M_WAITOK);
#ifdef VM_PHYSSEG_DENSE
        }
#endif
        vm_phys_fictitious_init_range(fp, start, page_count, memattr);

        seg = malloc(sizeof(*seg), M_FICT_PAGES, M_WAITOK | M_ZERO);
        seg->start = start;
        seg->end = end;
        seg->first_page = fp;

        rw_wlock(&vm_phys_fictitious_reg_lock);
        RB_INSERT(fict_tree, &vm_phys_fictitious_tree, seg);
        rw_wunlock(&vm_phys_fictitious_reg_lock);

        return (0);
}

void
vm_phys_fictitious_unreg_range(vm_paddr_t start, vm_paddr_t end)
{
        struct vm_phys_fictitious_seg *seg, tmp;
#ifdef VM_PHYSSEG_DENSE
        long pi, pe;
#endif

        KASSERT(start < end,
            ("Start of segment isn't less than end (start: %jx end: %jx)",
            (uintmax_t)start, (uintmax_t)end));

#ifdef VM_PHYSSEG_DENSE
        pi = atop(start);
        pe = atop(end);
        if (pi >= first_page && (pi - first_page) < vm_page_array_size) {
                if ((pe - first_page) <= vm_page_array_size) {
                        /*
                         * This segment was allocated using vm_page_array
                         * only, there's nothing to do since those pages
                         * were never added to the tree.
                         */
                        return;
                }
                /*
                 * We have a segment that starts inside
                 * of vm_page_array, but ends outside of it.
                 *
                 * Calculate how many pages were added to the
                 * tree and free them.
                 */
                start = ptoa(first_page + vm_page_array_size);
        } else if (pe > first_page && (pe - first_page) < vm_page_array_size) {
                /*
                 * We have a segment that ends inside of vm_page_array,
                 * but starts outside of it.
                 */
                end = ptoa(first_page);
        } else if (pi < first_page && pe > (first_page + vm_page_array_size)) {
                /* Since it's not possible to register such a range, panic. */
                panic(
                    "Unregistering not registered fictitious range [%#jx:%#jx]",
                    (uintmax_t)start, (uintmax_t)end);
        }
#endif
        tmp.start = start;
        tmp.end = 0;

        rw_wlock(&vm_phys_fictitious_reg_lock);
        seg = RB_FIND(fict_tree, &vm_phys_fictitious_tree, &tmp);
        if (seg->start != start || seg->end != end) {
                rw_wunlock(&vm_phys_fictitious_reg_lock);
                panic(
                    "Unregistering not registered fictitious range [%#jx:%#jx]",
                    (uintmax_t)start, (uintmax_t)end);
        }
        RB_REMOVE(fict_tree, &vm_phys_fictitious_tree, seg);
        rw_wunlock(&vm_phys_fictitious_reg_lock);
        free(seg->first_page, M_FICT_PAGES);
        free(seg, M_FICT_PAGES);
}

/*
 * Free a contiguous, power of two-sized set of physical pages.
 *
 * The free page queues must be locked.
 */
void
vm_phys_free_pages(vm_page_t m, int order)
{
        struct vm_freelist *fl;
        struct vm_phys_seg *seg;
        vm_paddr_t pa;
        vm_page_t m_buddy;

        KASSERT(m->order == VM_NFREEORDER,
            ("vm_phys_free_pages: page %p has unexpected order %d",
            m, m->order));
        KASSERT(m->pool < VM_NFREEPOOL,
            ("vm_phys_free_pages: page %p has unexpected pool %d",
            m, m->pool));
        KASSERT(order < VM_NFREEORDER,
            ("vm_phys_free_pages: order %d is out of range", order));
        seg = &vm_phys_segs[m->segind];
        vm_domain_free_assert_locked(VM_DOMAIN(seg->domain));
        if (order < VM_NFREEORDER - 1) {
                pa = VM_PAGE_TO_PHYS(m);
                do {
                        pa ^= ((vm_paddr_t)1 << (PAGE_SHIFT + order));
                        if (pa < seg->start || pa >= seg->end)
                                break;
                        m_buddy = &seg->first_page[atop(pa - seg->start)];
                        if (m_buddy->order != order)
                                break;
                        fl = (*seg->free_queues)[m_buddy->pool];
                        vm_freelist_rem(fl, m_buddy, order);
                        if (m_buddy->pool != m->pool)
                                vm_phys_set_pool(m->pool, m_buddy, order);
                        order++;
                        pa &= ~(((vm_paddr_t)1 << (PAGE_SHIFT + order)) - 1);
                        m = &seg->first_page[atop(pa - seg->start)];
                } while (order < VM_NFREEORDER - 1);
        }
        fl = (*seg->free_queues)[m->pool];
        vm_freelist_add(fl, m, order, 1);
}

/*
 * Return the largest possible order of a set of pages starting at m.
 */
static int
max_order(vm_page_t m)
{

        /*
         * Unsigned "min" is used here so that "order" is assigned
         * "VM_NFREEORDER - 1" when "m"'s physical address is zero
         * or the low-order bits of its physical address are zero
         * because the size of a physical address exceeds the size of
         * a long.
         */
        return (min(ffsl(VM_PAGE_TO_PHYS(m) >> PAGE_SHIFT) - 1,
            VM_NFREEORDER - 1));
}

/*
 * Free a contiguous, arbitrarily sized set of physical pages, without
 * merging across set boundaries.
 *
 * The free page queues must be locked.
 */
void
vm_phys_enqueue_contig(vm_page_t m, u_long npages)
{
        struct vm_freelist *fl;
        struct vm_phys_seg *seg;
        vm_page_t m_end;
        int order;

        /*
         * Avoid unnecessary coalescing by freeing the pages in the largest
         * possible power-of-two-sized subsets.
         */
        vm_domain_free_assert_locked(vm_pagequeue_domain(m));
        seg = &vm_phys_segs[m->segind];
        fl = (*seg->free_queues)[m->pool];
        m_end = m + npages;
        /* Free blocks of increasing size. */
        while ((order = max_order(m)) < VM_NFREEORDER - 1 &&
            m + (1 << order) <= m_end) {
                KASSERT(seg == &vm_phys_segs[m->segind],
                    ("%s: page range [%p,%p) spans multiple segments",
                    __func__, m_end - npages, m));
                vm_freelist_add(fl, m, order, 1);
                m += 1 << order;
        }
        /* Free blocks of maximum size. */
        while (m + (1 << order) <= m_end) {
                KASSERT(seg == &vm_phys_segs[m->segind],
                    ("%s: page range [%p,%p) spans multiple segments",
                    __func__, m_end - npages, m));
                vm_freelist_add(fl, m, order, 1);
                m += 1 << order;
        }
        /* Free blocks of diminishing size. */
        while (m < m_end) {
                KASSERT(seg == &vm_phys_segs[m->segind],
                    ("%s: page range [%p,%p) spans multiple segments",
                    __func__, m_end - npages, m));
                order = flsl(m_end - m) - 1;
                vm_freelist_add(fl, m, order, 1);
                m += 1 << order;
        }
}

/*
 * Free a contiguous, arbitrarily sized set of physical pages.
 *
 * The free page queues must be locked.
 */
void
vm_phys_free_contig(vm_page_t m, u_long npages)
{
        int order_start, order_end;
        vm_page_t m_start, m_end;

        vm_domain_free_assert_locked(vm_pagequeue_domain(m));

        m_start = m;
        order_start = max_order(m_start);
        if (order_start < VM_NFREEORDER - 1)
                m_start += 1 << order_start;
        m_end = m + npages;
        order_end = max_order(m_end);
        if (order_end < VM_NFREEORDER - 1)
                m_end -= 1 << order_end;
        /*
         * Avoid unnecessary coalescing by freeing the pages at the start and
         * end of the range last.
         */
        if (m_start < m_end)
                vm_phys_enqueue_contig(m_start, m_end - m_start);
        if (order_start < VM_NFREEORDER - 1)
                vm_phys_free_pages(m, order_start);
        if (order_end < VM_NFREEORDER - 1)
                vm_phys_free_pages(m_end, order_end);
}

/*
 * Scan physical memory between the specified addresses "low" and "high" for a
 * run of contiguous physical pages that satisfy the specified conditions, and
 * return the lowest page in the run.  The specified "alignment" determines
 * the alignment of the lowest physical page in the run.  If the specified
 * "boundary" is non-zero, then the run of physical pages cannot span a
 * physical address that is a multiple of "boundary".
 *
 * "npages" must be greater than zero.  Both "alignment" and "boundary" must
 * be a power of two.
 */
vm_page_t
vm_phys_scan_contig(int domain, u_long npages, vm_paddr_t low, vm_paddr_t high,
    u_long alignment, vm_paddr_t boundary, int options)
{
        vm_paddr_t pa_end;
        vm_page_t m_end, m_run, m_start;
        struct vm_phys_seg *seg;
        int segind;

        KASSERT(npages > 0, ("npages is 0"));
        KASSERT(powerof2(alignment), ("alignment is not a power of 2"));
        KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
        if (low >= high)
                return (NULL);
        for (segind = 0; segind < vm_phys_nsegs; segind++) {
                seg = &vm_phys_segs[segind];
                if (seg->domain != domain)
                        continue;
                if (seg->start >= high)
                        break;
                if (low >= seg->end)
                        continue;
                if (low <= seg->start)
                        m_start = seg->first_page;
                else
                        m_start = &seg->first_page[atop(low - seg->start)];
                if (high < seg->end)
                        pa_end = high;
                else
                        pa_end = seg->end;
                if (pa_end - VM_PAGE_TO_PHYS(m_start) < ptoa(npages))
                        continue;
                m_end = &seg->first_page[atop(pa_end - seg->start)];
                m_run = vm_page_scan_contig(npages, m_start, m_end,
                    alignment, boundary, options);
                if (m_run != NULL)
                        return (m_run);
        }
        return (NULL);
}

/*
 * Search for the given physical page "m" in the free lists.  If the search
 * succeeds, remove "m" from the free lists and return TRUE.  Otherwise, return
 * FALSE, indicating that "m" is not in the free lists.
 *
 * The free page queues must be locked.
 */
boolean_t
vm_phys_unfree_page(vm_page_t m)
{
        struct vm_freelist *fl;
        struct vm_phys_seg *seg;
        vm_paddr_t pa, pa_half;
        vm_page_t m_set, m_tmp;
        int order;

        /*
         * First, find the contiguous, power of two-sized set of free
         * physical pages containing the given physical page "m" and
         * assign it to "m_set".
         */
        seg = &vm_phys_segs[m->segind];
        vm_domain_free_assert_locked(VM_DOMAIN(seg->domain));
        for (m_set = m, order = 0; m_set->order == VM_NFREEORDER &&
            order < VM_NFREEORDER - 1; ) {
                order++;
                pa = m->phys_addr & (~(vm_paddr_t)0 << (PAGE_SHIFT + order));
                if (pa >= seg->start)
                        m_set = &seg->first_page[atop(pa - seg->start)];
                else
                        return (FALSE);
        }
        if (m_set->order < order)
                return (FALSE);
        if (m_set->order == VM_NFREEORDER)
                return (FALSE);
        KASSERT(m_set->order < VM_NFREEORDER,
            ("vm_phys_unfree_page: page %p has unexpected order %d",
            m_set, m_set->order));

        /*
         * Next, remove "m_set" from the free lists.  Finally, extract
         * "m" from "m_set" using an iterative algorithm: While "m_set"
         * is larger than a page, shrink "m_set" by returning the half
         * of "m_set" that does not contain "m" to the free lists.
         */
        fl = (*seg->free_queues)[m_set->pool];
        order = m_set->order;
        vm_freelist_rem(fl, m_set, order);
        while (order > 0) {
                order--;
                pa_half = m_set->phys_addr ^ (1 << (PAGE_SHIFT + order));
                if (m->phys_addr < pa_half)
                        m_tmp = &seg->first_page[atop(pa_half - seg->start)];
                else {
                        m_tmp = m_set;
                        m_set = &seg->first_page[atop(pa_half - seg->start)];
                }
                vm_freelist_add(fl, m_tmp, order, 0);
        }
        KASSERT(m_set == m, ("vm_phys_unfree_page: fatal inconsistency"));
        return (TRUE);
}

/*
 * Allocate a contiguous set of physical pages of the given size
 * "npages" from the free lists.  All of the physical pages must be at
 * or above the given physical address "low" and below the given
 * physical address "high".  The given value "alignment" determines the
 * alignment of the first physical page in the set.  If the given value
 * "boundary" is non-zero, then the set of physical pages cannot cross
 * any physical address boundary that is a multiple of that value.  Both
 * "alignment" and "boundary" must be a power of two.
 */
vm_page_t
vm_phys_alloc_contig(int domain, u_long npages, vm_paddr_t low, vm_paddr_t high,
    u_long alignment, vm_paddr_t boundary)
{
        vm_paddr_t pa_end, pa_start;
        vm_page_t m_run;
        struct vm_phys_seg *seg;
        int segind;

        KASSERT(npages > 0, ("npages is 0"));
        KASSERT(powerof2(alignment), ("alignment is not a power of 2"));
        KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
        vm_domain_free_assert_locked(VM_DOMAIN(domain));
        if (low >= high)
                return (NULL);
        m_run = NULL;
        for (segind = vm_phys_nsegs - 1; segind >= 0; segind--) {
                seg = &vm_phys_segs[segind];
                if (seg->start >= high || seg->domain != domain)
                        continue;
                if (low >= seg->end)
                        break;
                if (low <= seg->start)
                        pa_start = seg->start;
                else
                        pa_start = low;
                if (high < seg->end)
                        pa_end = high;
                else
                        pa_end = seg->end;
                if (pa_end - pa_start < ptoa(npages))
                        continue;
                m_run = vm_phys_alloc_seg_contig(seg, npages, low, high,
                    alignment, boundary);
                if (m_run != NULL)
                        break;
        }
        return (m_run);
}

/*
 * Allocate a run of contiguous physical pages from the free list for the
 * specified segment.
 */
static vm_page_t
vm_phys_alloc_seg_contig(struct vm_phys_seg *seg, u_long npages,
    vm_paddr_t low, vm_paddr_t high, u_long alignment, vm_paddr_t boundary)
{
        struct vm_freelist *fl;
        vm_paddr_t pa, pa_end, size;
        vm_page_t m, m_ret;
        u_long npages_end;
        int oind, order, pind;

        KASSERT(npages > 0, ("npages is 0"));
        KASSERT(powerof2(alignment), ("alignment is not a power of 2"));
        KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
        vm_domain_free_assert_locked(VM_DOMAIN(seg->domain));
        /* Compute the queue that is the best fit for npages. */
        order = flsl(npages - 1);
        /* Search for a run satisfying the specified conditions. */
        size = npages << PAGE_SHIFT;
        for (oind = min(order, VM_NFREEORDER - 1); oind < VM_NFREEORDER;
            oind++) {
                for (pind = 0; pind < VM_NFREEPOOL; pind++) {
                        fl = (*seg->free_queues)[pind];
                        TAILQ_FOREACH(m_ret, &fl[oind].pl, listq) {
                                /*
                                 * Is the size of this allocation request
                                 * larger than the largest block size?
                                 */
                                if (order >= VM_NFREEORDER) {
                                        /*
                                         * Determine if a sufficient number of
                                         * subsequent blocks to satisfy the
                                         * allocation request are free.
                                         */
                                        pa = VM_PAGE_TO_PHYS(m_ret);
                                        pa_end = pa + size;
                                        if (pa_end < pa)
                                                continue;
                                        for (;;) {
                                                pa += 1 << (PAGE_SHIFT +
                                                    VM_NFREEORDER - 1);
                                                if (pa >= pa_end ||
                                                    pa < seg->start ||
                                                    pa >= seg->end)
                                                        break;
                                                m = &seg->first_page[atop(pa -
                                                    seg->start)];
                                                if (m->order != VM_NFREEORDER -
                                                    1)
                                                        break;
                                        }
                                        /* If not, go to the next block. */
                                        if (pa < pa_end)
                                                continue;
                                }

                                /*
                                 * Determine if the blocks are within the
                                 * given range, satisfy the given alignment,
                                 * and do not cross the given boundary.
                                 */
                                pa = VM_PAGE_TO_PHYS(m_ret);
                                pa_end = pa + size;
                                if (pa >= low && pa_end <= high &&
                                    vm_addr_ok(pa, size, alignment, boundary))
                                        goto done;
                        }
                }
        }
        return (NULL);
done:
        for (m = m_ret; m < &m_ret[npages]; m = &m[1 << oind]) {
                fl = (*seg->free_queues)[m->pool];
                vm_freelist_rem(fl, m, oind);
                if (m->pool != VM_FREEPOOL_DEFAULT)
                        vm_phys_set_pool(VM_FREEPOOL_DEFAULT, m, oind);
        }
        /* Return excess pages to the free lists. */
        npages_end = roundup2(npages, 1 << oind);
        if (npages < npages_end) {
                fl = (*seg->free_queues)[VM_FREEPOOL_DEFAULT];
                vm_phys_enq_range(&m_ret[npages], npages_end - npages, fl, 0);
        }
        return (m_ret);
}

/*
 * Return the index of the first unused slot which may be the terminating
 * entry.
 */
static int
vm_phys_avail_count(void)
{
        int i;

        for (i = 0; phys_avail[i + 1]; i += 2)
                continue;
        if (i > PHYS_AVAIL_ENTRIES)
                panic("Improperly terminated phys_avail %d entries", i);

        return (i);
}

/*
 * Assert that a phys_avail entry is valid.
 */
static void
vm_phys_avail_check(int i)
{
        if (phys_avail[i] & PAGE_MASK)
                panic("Unaligned phys_avail[%d]: %#jx", i,
                    (intmax_t)phys_avail[i]);
        if (phys_avail[i+1] & PAGE_MASK)
                panic("Unaligned phys_avail[%d + 1]: %#jx", i,
                    (intmax_t)phys_avail[i]);
        if (phys_avail[i + 1] < phys_avail[i])
                panic("phys_avail[%d] start %#jx < end %#jx", i,
                    (intmax_t)phys_avail[i], (intmax_t)phys_avail[i+1]);
}

/*
 * Return the index of an overlapping phys_avail entry or -1.
 */
#ifdef NUMA
static int
vm_phys_avail_find(vm_paddr_t pa)
{
        int i;

        for (i = 0; phys_avail[i + 1]; i += 2)
                if (phys_avail[i] <= pa && phys_avail[i + 1] > pa)
                        return (i);
        return (-1);
}
#endif

/*
 * Return the index of the largest entry.
 */
int
vm_phys_avail_largest(void)
{
        vm_paddr_t sz, largesz;
        int largest;
        int i;

        largest = 0;
        largesz = 0;
        for (i = 0; phys_avail[i + 1]; i += 2) {
                sz = vm_phys_avail_size(i);
                if (sz > largesz) {
                        largesz = sz;
                        largest = i;
                }
        }

        return (largest);
}

vm_paddr_t
vm_phys_avail_size(int i)
{

        return (phys_avail[i + 1] - phys_avail[i]);
}

/*
 * Split an entry at the address 'pa'.  Return zero on success or errno.
 */
static int
vm_phys_avail_split(vm_paddr_t pa, int i)
{
        int cnt;

        vm_phys_avail_check(i);
        if (pa <= phys_avail[i] || pa >= phys_avail[i + 1])
                panic("vm_phys_avail_split: invalid address");
        cnt = vm_phys_avail_count();
        if (cnt >= PHYS_AVAIL_ENTRIES)
                return (ENOSPC);
        memmove(&phys_avail[i + 2], &phys_avail[i],
            (cnt - i) * sizeof(phys_avail[0]));
        phys_avail[i + 1] = pa;
        phys_avail[i + 2] = pa;
        vm_phys_avail_check(i);
        vm_phys_avail_check(i+2);

        return (0);
}

/*
 * Check if a given physical address can be included as part of a crash dump.
 */
bool
vm_phys_is_dumpable(vm_paddr_t pa)
{
        vm_page_t m;
        int i;

        if ((m = vm_phys_paddr_to_vm_page(pa)) != NULL)
                return ((m->flags & PG_NODUMP) == 0);

        for (i = 0; dump_avail[i] != 0 || dump_avail[i + 1] != 0; i += 2) {
                if (pa >= dump_avail[i] && pa < dump_avail[i + 1])
                        return (true);
        }
        return (false);
}

void
vm_phys_early_add_seg(vm_paddr_t start, vm_paddr_t end)
{
        struct vm_phys_seg *seg;

        if (vm_phys_early_nsegs == -1)
                panic("%s: called after initialization", __func__);
        if (vm_phys_early_nsegs == nitems(vm_phys_early_segs))
                panic("%s: ran out of early segments", __func__);

        seg = &vm_phys_early_segs[vm_phys_early_nsegs++];
        seg->start = start;
        seg->end = end;
}

/*
 * This routine allocates NUMA node specific memory before the page
 * allocator is bootstrapped.
 */
vm_paddr_t
vm_phys_early_alloc(int domain, size_t alloc_size)
{
        int i, mem_index, biggestone;
        vm_paddr_t pa, mem_start, mem_end, size, biggestsize, align;

        KASSERT(domain == -1 || (domain >= 0 && domain < vm_ndomains),
            ("%s: invalid domain index %d", __func__, domain));

        /*
         * Search the mem_affinity array for the biggest address
         * range in the desired domain.  This is used to constrain
         * the phys_avail selection below.
         */
        biggestsize = 0;
        mem_index = 0;
        mem_start = 0;
        mem_end = -1;
#ifdef NUMA
        if (mem_affinity != NULL) {
                for (i = 0;; i++) {
                        size = mem_affinity[i].end - mem_affinity[i].start;
                        if (size == 0)
                                break;
                        if (domain != -1 && mem_affinity[i].domain != domain)
                                continue;
                        if (size > biggestsize) {
                                mem_index = i;
                                biggestsize = size;
                        }
                }
                mem_start = mem_affinity[mem_index].start;
                mem_end = mem_affinity[mem_index].end;
        }
#endif

        /*
         * Now find biggest physical segment in within the desired
         * numa domain.
         */
        biggestsize = 0;
        biggestone = 0;
        for (i = 0; phys_avail[i + 1] != 0; i += 2) {
                /* skip regions that are out of range */
                if (phys_avail[i+1] - alloc_size < mem_start ||
                    phys_avail[i+1] > mem_end)
                        continue;
                size = vm_phys_avail_size(i);
                if (size > biggestsize) {
                        biggestone = i;
                        biggestsize = size;
                }
        }
        alloc_size = round_page(alloc_size);

        /*
         * Grab single pages from the front to reduce fragmentation.
         */
        if (alloc_size == PAGE_SIZE) {
                pa = phys_avail[biggestone];
                phys_avail[biggestone] += PAGE_SIZE;
                vm_phys_avail_check(biggestone);
                return (pa);
        }

        /*
         * Naturally align large allocations.
         */
        align = phys_avail[biggestone + 1] & (alloc_size - 1);
        if (alloc_size + align > biggestsize)
                panic("cannot find a large enough size\n");
        if (align != 0 &&
            vm_phys_avail_split(phys_avail[biggestone + 1] - align,
            biggestone) != 0)
                /* Wasting memory. */
                phys_avail[biggestone + 1] -= align;

        phys_avail[biggestone + 1] -= alloc_size;
        vm_phys_avail_check(biggestone);
        pa = phys_avail[biggestone + 1];
        return (pa);
}

void
vm_phys_early_startup(void)
{
        struct vm_phys_seg *seg;
        int i;

        for (i = 0; phys_avail[i + 1] != 0; i += 2) {
                phys_avail[i] = round_page(phys_avail[i]);
                phys_avail[i + 1] = trunc_page(phys_avail[i + 1]);
        }

        for (i = 0; i < vm_phys_early_nsegs; i++) {
                seg = &vm_phys_early_segs[i];
                vm_phys_add_seg(seg->start, seg->end);
        }
        vm_phys_early_nsegs = -1;

#ifdef NUMA
        /* Force phys_avail to be split by domain. */
        if (mem_affinity != NULL) {
                int idx;

                for (i = 0; mem_affinity[i].end != 0; i++) {
                        idx = vm_phys_avail_find(mem_affinity[i].start);
                        if (idx != -1 &&
                            phys_avail[idx] != mem_affinity[i].start)
                                vm_phys_avail_split(mem_affinity[i].start, idx);
                        idx = vm_phys_avail_find(mem_affinity[i].end);
                        if (idx != -1 &&
                            phys_avail[idx] != mem_affinity[i].end)
                                vm_phys_avail_split(mem_affinity[i].end, idx);
                }
        }
#endif
}

#ifdef DDB
/*
 * Show the number of physical pages in each of the free lists.
 */
DB_SHOW_COMMAND(freepages, db_show_freepages)
{
        struct vm_freelist *fl;
        int flind, oind, pind, dom;

        for (dom = 0; dom < vm_ndomains; dom++) {
                db_printf("DOMAIN: %d\n", dom);
                for (flind = 0; flind < vm_nfreelists; flind++) {
                        db_printf("FREE LIST %d:\n"
                            "\n  ORDER (SIZE)  |  NUMBER"
                            "\n              ", flind);
                        for (pind = 0; pind < VM_NFREEPOOL; pind++)
                                db_printf("  |  POOL %d", pind);
                        db_printf("\n--            ");
                        for (pind = 0; pind < VM_NFREEPOOL; pind++)
                                db_printf("-- --      ");
                        db_printf("--\n");
                        for (oind = VM_NFREEORDER - 1; oind >= 0; oind--) {
                                db_printf("  %2.2d (%6.6dK)", oind,
                                    1 << (PAGE_SHIFT - 10 + oind));
                                for (pind = 0; pind < VM_NFREEPOOL; pind++) {
                                fl = vm_phys_free_queues[dom][flind][pind];
                                        db_printf("  |  %6.6d", fl[oind].lcnt);
                                }
                                db_printf("\n");
                        }
                        db_printf("\n");
                }
                db_printf("\n");
        }
}
#endif