/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c)2006,2007,2008,2009 YAMAMOTO Takashi,
 * Copyright (c) 2013 EMC Corp.
 * All rights reserved.
 *
 * 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.
 */

/*
 * From:
 *      $NetBSD: vmem_impl.h,v 1.2 2013/01/29 21:26:24 para Exp $
 *      $NetBSD: subr_vmem.c,v 1.83 2013/03/06 11:20:10 yamt Exp $
 */

/*
 * reference:
 * -    Magazines and Vmem: Extending the Slab Allocator
 *      to Many CPUs and Arbitrary Resources
 *      http://www.usenix.org/event/usenix01/bonwick.html
 */

#include <sys/cdefs.h>

#ifdef _KERNEL

#include "opt_ddb.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/queue.h>
#include <sys/callout.h>
#include <sys/hash.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/smp.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/taskqueue.h>
#include <sys/vmem.h>
#include <sys/vmmeter.h>

#include "opt_vm.h"

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

#else   /* _KERNEL */

#include <sys/types.h>
#include <sys/queue.h>
#include <sys/hash.h>
#include <sys/vmem.h>
#include <assert.h>
#include <errno.h>
#include <pthread.h>
#include <pthread_np.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>

#define KASSERT(a, b)
#define MPASS(a)
#define WITNESS_WARN(a, b, c)
#define panic(...) assert(0)

#endif  /* _KERNEL */

#define VMEM_OPTORDER           5
#define VMEM_OPTVALUE           (1 << VMEM_OPTORDER)
#define VMEM_MAXORDER                                           \
    (VMEM_OPTVALUE - 1 + sizeof(vmem_size_t) * NBBY - VMEM_OPTORDER)

#define VMEM_HASHSIZE_MIN       16
#define VMEM_HASHSIZE_MAX       131072

#define VMEM_QCACHE_IDX_MAX     16

#define VMEM_FITMASK    (M_BESTFIT | M_FIRSTFIT | M_NEXTFIT)

#define QC_NAME_MAX     16

/*
 * Data structures private to vmem.
 */
#ifdef _KERNEL

#define VMEM_FLAGS      (M_NOWAIT | M_WAITOK | M_USE_RESERVE | M_NOVM | \
    M_BESTFIT | M_FIRSTFIT | M_NEXTFIT)

#define BT_FLAGS        (M_NOWAIT | M_WAITOK | M_USE_RESERVE | M_NOVM)

MALLOC_DEFINE(M_VMEM, "vmem", "vmem internal structures");

#else   /* _KERNEL */

/* bit-compat with kernel */
#define M_ZERO          0
#define M_NOVM          0
#define M_USE_RESERVE   0

#define VMEM_FLAGS      (M_NOWAIT | M_BESTFIT | M_FIRSTFIT | M_NEXTFIT)

#define BT_FLAGS        0

#endif  /* _KERNEL */

typedef struct vmem_btag bt_t;

TAILQ_HEAD(vmem_seglist, vmem_btag);
LIST_HEAD(vmem_freelist, vmem_btag);
LIST_HEAD(vmem_hashlist, vmem_btag);

#ifdef _KERNEL
struct qcache {
        uma_zone_t      qc_cache;
        vmem_t          *qc_vmem;
        vmem_size_t     qc_size;
        char            qc_name[QC_NAME_MAX];
};
typedef struct qcache qcache_t;
#define QC_POOL_TO_QCACHE(pool) ((qcache_t *)(pool->pr_qcache))
#endif

#define VMEM_NAME_MAX   16

/* boundary tag */
struct vmem_btag {
        TAILQ_ENTRY(vmem_btag) bt_seglist;
        union {
                LIST_ENTRY(vmem_btag) u_freelist; /* BT_TYPE_FREE */
                LIST_ENTRY(vmem_btag) u_hashlist; /* BT_TYPE_BUSY */
        } bt_u;
#define bt_hashlist     bt_u.u_hashlist
#define bt_freelist     bt_u.u_freelist
        vmem_addr_t     bt_start;
        vmem_size_t     bt_size;
        int             bt_type;
};

/* vmem arena */
struct vmem {
#ifdef _KERNEL
        struct mtx_padalign     vm_lock;
        struct cv               vm_cv;
#else
        pthread_mutex_t         vm_lock;
        pthread_cond_t          vm_cv;
#endif
        char                    vm_name[VMEM_NAME_MAX+1];
        LIST_ENTRY(vmem)        vm_alllist;
        struct vmem_hashlist    vm_hash0[VMEM_HASHSIZE_MIN];
        struct vmem_freelist    vm_freelist[VMEM_MAXORDER];
        struct vmem_seglist     vm_seglist;
        struct vmem_hashlist    *vm_hashlist;
        vmem_size_t             vm_hashsize;

        /* Constant after init */
        vmem_size_t             vm_qcache_max;
        vmem_size_t             vm_quantum_mask;
        vmem_size_t             vm_import_quantum;
        int                     vm_quantum_shift;

        /* Written on alloc/free */
        LIST_HEAD(, vmem_btag)  vm_freetags;
        int                     vm_nfreetags;
        int                     vm_nbusytag;
        vmem_size_t             vm_inuse;
        vmem_size_t             vm_size;
        vmem_size_t             vm_limit;
        struct vmem_btag        vm_cursor;

        /* Used on import. */
        vmem_import_t           *vm_importfn;
        vmem_release_t          *vm_releasefn;
        void                    *vm_arg;

        /* Space exhaustion callback. */
        vmem_reclaim_t          *vm_reclaimfn;

#ifdef _KERNEL
        /* quantum cache */
        qcache_t                vm_qcache[VMEM_QCACHE_IDX_MAX];
#endif
};

#define BT_TYPE_SPAN            1       /* Allocated from importfn */
#define BT_TYPE_SPAN_STATIC     2       /* vmem_add() or create. */
#define BT_TYPE_FREE            3       /* Available space. */
#define BT_TYPE_BUSY            4       /* Used space. */
#define BT_TYPE_CURSOR          5       /* Cursor for nextfit allocations. */
#define BT_ISSPAN_P(bt) ((bt)->bt_type <= BT_TYPE_SPAN_STATIC)

#define BT_END(bt)      ((bt)->bt_start + (bt)->bt_size - 1)

#ifdef _KERNEL
#if defined(DIAGNOSTIC)
static int enable_vmem_check = 0;
SYSCTL_INT(_debug, OID_AUTO, vmem_check, CTLFLAG_RWTUN,
    &enable_vmem_check, 0, "Enable vmem check");
static void vmem_check(vmem_t *);
#endif

static struct callout   vmem_periodic_ch;
static int              vmem_periodic_interval;
static struct task      vmem_periodic_wk;

static struct mtx_padalign __exclusive_cache_line vmem_list_lock;
static uma_zone_t vmem_zone;

#else   /* _KERNEL */
static pthread_mutex_t vmem_list_lock = PTHREAD_MUTEX_INITIALIZER;

#endif  /* _KERNEL */

static LIST_HEAD(, vmem) vmem_list = LIST_HEAD_INITIALIZER(vmem_list);

/* ---- misc */
#ifdef _KERNEL
#define VMEM_LIST_LOCK()                mtx_lock(&vmem_list_lock)
#define VMEM_LIST_UNLOCK()              mtx_unlock(&vmem_list_lock)

#define VMEM_CONDVAR_INIT(vm, wchan)    cv_init(&vm->vm_cv, wchan)
#define VMEM_CONDVAR_DESTROY(vm)        cv_destroy(&vm->vm_cv)
#define VMEM_CONDVAR_WAIT(vm)           cv_wait(&vm->vm_cv, &vm->vm_lock)
#define VMEM_CONDVAR_BROADCAST(vm)      cv_broadcast(&vm->vm_cv)

#define VMEM_LOCK(vm)           mtx_lock(&vm->vm_lock)
#define VMEM_UNLOCK(vm)         mtx_unlock(&vm->vm_lock)
#define VMEM_LOCK_INIT(vm, name) mtx_init(&vm->vm_lock, (name), NULL, MTX_DEF)
#define VMEM_LOCK_DESTROY(vm)   mtx_destroy(&vm->vm_lock)
#define VMEM_ASSERT_LOCKED(vm)  mtx_assert(&vm->vm_lock, MA_OWNED);
#else   /* _KERNEL */
#define VMEM_LIST_LOCK()                pthread_mutex_lock(&vmem_list_lock)
#define VMEM_LIST_UNLOCK()              pthread_mutex_unlock(&vmem_list_lock)

#define VMEM_CONDVAR_INIT(vm, wchan)    pthread_cond_init(&vm->vm_cv, NULL)
#define VMEM_CONDVAR_DESTROY(vm)        pthread_cond_destroy(&vm->vm_cv)
#define VMEM_CONDVAR_WAIT(vm)   pthread_cond_wait(&vm->vm_cv, &vm->vm_lock)
#define VMEM_CONDVAR_BROADCAST(vm)      pthread_cond_broadcast(&vm->vm_cv)

#define VMEM_LOCK(vm)           pthread_mutex_lock(&vm->vm_lock)
#define VMEM_UNLOCK(vm)         pthread_mutex_unlock(&vm->vm_lock)
#define VMEM_LOCK_INIT(vm, name) pthread_mutex_init(&vm->vm_lock, NULL)
#define VMEM_LOCK_DESTROY(vm)   pthread_mutex_destroy(&vm->vm_lock)
#define VMEM_ASSERT_LOCKED(vm)  pthread_mutex_isowned_np(&vm->vm_lock)
#endif  /* _KERNEL */

#define VMEM_ALIGNUP(addr, align)       (-(-(addr) & -(align)))

#define VMEM_CROSS_P(addr1, addr2, boundary) \
        ((((addr1) ^ (addr2)) & -(boundary)) != 0)

#define ORDER2SIZE(order)       ((order) < VMEM_OPTVALUE ?      \
        (vmem_size_t)((order) + 1) :                            \
        (vmem_size_t)1 << ((order) - (VMEM_OPTVALUE - VMEM_OPTORDER - 1)))
#define SIZE2ORDER(size)        ((size) <= VMEM_OPTVALUE ?      \
        (int)((size) - 1) :                                     \
        (flsl(size) + (VMEM_OPTVALUE - VMEM_OPTORDER - 2)))

/*
 * Maximum number of boundary tags that may be required to satisfy an
 * allocation.  Two may be required to import.  Another two may be
 * required to clip edges.
 */
#define BT_MAXALLOC     4

/*
 * Max free limits the number of locally cached boundary tags.  We
 * just want to avoid hitting the zone allocator for every call.
 */
#define BT_MAXFREE      (BT_MAXALLOC * 8)

#ifdef _KERNEL
/* Allocator for boundary tags. */
static uma_zone_t vmem_bt_zone;

/* boot time arena storage. */
static struct vmem kernel_arena_storage;
static struct vmem buffer_arena_storage;
static struct vmem transient_arena_storage;
vmem_t *kernel_arena = &kernel_arena_storage;
vmem_t *buffer_arena = &buffer_arena_storage;
vmem_t *transient_arena = &transient_arena_storage;

#ifdef DEBUG_MEMGUARD
static struct vmem memguard_arena_storage;
vmem_t *memguard_arena = &memguard_arena_storage;
#endif  /* DEBUG_MEMGUARD */
#endif  /* _KERNEL */

static bool
bt_isbusy(bt_t *bt)
{
        return (bt->bt_type == BT_TYPE_BUSY);
}

static bool
bt_isfree(bt_t *bt)
{
        return (bt->bt_type == BT_TYPE_FREE);
}

/*
 * Fill the vmem's boundary tag cache.  We guarantee that boundary tag
 * allocation will not fail once bt_fill() passes.  To do so we cache
 * at least the maximum possible tag allocations in the arena.
 */
static __noinline int
_bt_fill(vmem_t *vm, int flags __unused)
{
        bt_t *bt;

        VMEM_ASSERT_LOCKED(vm);

#ifdef _KERNEL
        /*
         * Only allow the kernel arena and arenas derived from kernel arena to
         * dip into reserve tags.  They are where new tags come from.
         */
        flags &= BT_FLAGS;
        if (vm != kernel_arena && vm->vm_arg != kernel_arena)
                flags &= ~M_USE_RESERVE;
#endif

        /*
         * Loop until we meet the reserve.  To minimize the lock shuffle
         * and prevent simultaneous fills we first try a NOWAIT regardless
         * of the caller's flags.  Specify M_NOVM so we don't recurse while
         * holding a vmem lock.
         */
        while (vm->vm_nfreetags < BT_MAXALLOC) {
#ifdef _KERNEL
                bt = uma_zalloc(vmem_bt_zone,
                    (flags & M_USE_RESERVE) | M_NOWAIT | M_NOVM);
#else
                bt = malloc(sizeof(struct vmem_btag));
#endif
                if (bt == NULL) {
#ifdef _KERNEL
                        VMEM_UNLOCK(vm);
                        bt = uma_zalloc(vmem_bt_zone, flags);
                        VMEM_LOCK(vm);
#endif
                        if (bt == NULL)
                                break;
                }
                LIST_INSERT_HEAD(&vm->vm_freetags, bt, bt_freelist);
                vm->vm_nfreetags++;
        }

        if (vm->vm_nfreetags < BT_MAXALLOC)
                return ENOMEM;

        return 0;
}

static inline int
bt_fill(vmem_t *vm, int flags)
{
        if (vm->vm_nfreetags >= BT_MAXALLOC)
                return (0);
        return (_bt_fill(vm, flags));
}

/*
 * Pop a tag off of the freetag stack.
 */
static bt_t *
bt_alloc(vmem_t *vm)
{
        bt_t *bt;

        VMEM_ASSERT_LOCKED(vm);
        bt = LIST_FIRST(&vm->vm_freetags);
        MPASS(bt != NULL);
        LIST_REMOVE(bt, bt_freelist);
        vm->vm_nfreetags--;

        return bt;
}

/*
 * Trim the per-vmem free list.  Returns with the lock released to
 * avoid allocator recursions.
 */
static void
bt_freetrim(vmem_t *vm, int freelimit)
{
        LIST_HEAD(, vmem_btag) freetags;
        bt_t *bt;

        LIST_INIT(&freetags);
        VMEM_ASSERT_LOCKED(vm);
        while (vm->vm_nfreetags > freelimit) {
                bt = LIST_FIRST(&vm->vm_freetags);
                LIST_REMOVE(bt, bt_freelist);
                vm->vm_nfreetags--;
                LIST_INSERT_HEAD(&freetags, bt, bt_freelist);
        }
        VMEM_UNLOCK(vm);
        while ((bt = LIST_FIRST(&freetags)) != NULL) {
                LIST_REMOVE(bt, bt_freelist);
#ifdef  _KERNEL
                uma_zfree(vmem_bt_zone, bt);
#else
                free(bt);
#endif
        }
}

static inline void
bt_free(vmem_t *vm, bt_t *bt)
{

        VMEM_ASSERT_LOCKED(vm);
        MPASS(LIST_FIRST(&vm->vm_freetags) != bt);
        LIST_INSERT_HEAD(&vm->vm_freetags, bt, bt_freelist);
        vm->vm_nfreetags++;
}

/*
 * Hide MAXALLOC tags before dropping the arena lock to ensure that a
 * concurrent allocation attempt does not grab them.
 */
static void
bt_save(vmem_t *vm)
{
        KASSERT(vm->vm_nfreetags >= BT_MAXALLOC,
            ("%s: insufficient free tags %d", __func__, vm->vm_nfreetags));
        vm->vm_nfreetags -= BT_MAXALLOC;
}

static void
bt_restore(vmem_t *vm)
{
        vm->vm_nfreetags += BT_MAXALLOC;
}

/*
 * freelist[0] ... [1, 1]
 * freelist[1] ... [2, 2]
 *  :
 * freelist[29] ... [30, 30]
 * freelist[30] ... [31, 31]
 * freelist[31] ... [32, 63]
 * freelist[33] ... [64, 127]
 *  :
 * freelist[n] ... [(1 << (n - 26)), (1 << (n - 25)) - 1]
 *  :
 */

static struct vmem_freelist *
bt_freehead_tofree(vmem_t *vm, vmem_size_t size)
{
        const vmem_size_t qsize = size >> vm->vm_quantum_shift;
        const int idx = SIZE2ORDER(qsize);

        MPASS(size != 0 && qsize != 0);
        MPASS((size & vm->vm_quantum_mask) == 0);
        MPASS(idx >= 0);
        MPASS(idx < VMEM_MAXORDER);

        return &vm->vm_freelist[idx];
}

/*
 * bt_freehead_toalloc: return the freelist for the given size and allocation
 * strategy.
 *
 * For M_FIRSTFIT, return the list in which any blocks are large enough
 * for the requested size.  otherwise, return the list which can have blocks
 * large enough for the requested size.
 */
static struct vmem_freelist *
bt_freehead_toalloc(vmem_t *vm, vmem_size_t size, int strat)
{
        const vmem_size_t qsize = size >> vm->vm_quantum_shift;
        int idx = SIZE2ORDER(qsize);

        MPASS(size != 0 && qsize != 0);
        MPASS((size & vm->vm_quantum_mask) == 0);

        if (strat == M_FIRSTFIT && ORDER2SIZE(idx) != qsize) {
                idx++;
                /* check too large request? */
        }
        MPASS(idx >= 0);
        MPASS(idx < VMEM_MAXORDER);

        return &vm->vm_freelist[idx];
}

/* ---- boundary tag hash */

static struct vmem_hashlist *
bt_hashhead(vmem_t *vm, vmem_addr_t addr)
{
        struct vmem_hashlist *list;
        unsigned int hash;

        hash = hash32_buf(&addr, sizeof(addr), 0);
        list = &vm->vm_hashlist[hash % vm->vm_hashsize];

        return list;
}

static bt_t *
bt_lookupbusy(vmem_t *vm, vmem_addr_t addr)
{
        struct vmem_hashlist *list;
        bt_t *bt;

        VMEM_ASSERT_LOCKED(vm);
        list = bt_hashhead(vm, addr); 
        LIST_FOREACH(bt, list, bt_hashlist) {
                if (bt->bt_start == addr) {
                        break;
                }
        }

        return bt;
}

static void
bt_rembusy(vmem_t *vm, bt_t *bt)
{

        VMEM_ASSERT_LOCKED(vm);
        MPASS(vm->vm_nbusytag > 0);
        vm->vm_inuse -= bt->bt_size;
        vm->vm_nbusytag--;
        LIST_REMOVE(bt, bt_hashlist);
}

static void
bt_insbusy(vmem_t *vm, bt_t *bt)
{
        struct vmem_hashlist *list;

        VMEM_ASSERT_LOCKED(vm);
        MPASS(bt->bt_type == BT_TYPE_BUSY);

        list = bt_hashhead(vm, bt->bt_start);
        LIST_INSERT_HEAD(list, bt, bt_hashlist);
        vm->vm_nbusytag++;
        vm->vm_inuse += bt->bt_size;
}

/* ---- boundary tag list */

static void
bt_remseg(vmem_t *vm, bt_t *bt)
{

        MPASS(bt->bt_type != BT_TYPE_CURSOR);
        TAILQ_REMOVE(&vm->vm_seglist, bt, bt_seglist);
        bt_free(vm, bt);
}

static void
bt_insseg(vmem_t *vm, bt_t *bt, bt_t *prev)
{

        TAILQ_INSERT_AFTER(&vm->vm_seglist, prev, bt, bt_seglist);
}

static void
bt_insseg_tail(vmem_t *vm, bt_t *bt)
{

        TAILQ_INSERT_TAIL(&vm->vm_seglist, bt, bt_seglist);
}

static void
bt_remfree(vmem_t *vm __unused, bt_t *bt)
{

        MPASS(bt->bt_type == BT_TYPE_FREE);

        LIST_REMOVE(bt, bt_freelist);
}

static void
bt_insfree(vmem_t *vm, bt_t *bt)
{
        struct vmem_freelist *list;

        list = bt_freehead_tofree(vm, bt->bt_size);
        LIST_INSERT_HEAD(list, bt, bt_freelist);
}

/* ---- vmem internal functions */

#ifdef _KERNEL
/*
 * Import from the arena into the quantum cache in UMA.
 *
 * We use VMEM_ADDR_QCACHE_MIN instead of 0: uma_zalloc() returns 0 to indicate
 * failure, so UMA can't be used to cache a resource with value 0.
 */
static int
qc_import(void *arg, void **store, int cnt, int domain, int flags)
{
        qcache_t *qc;
        vmem_addr_t addr;
        int i;

        KASSERT((flags & M_WAITOK) == 0, ("blocking allocation"));

        qc = arg;
        for (i = 0; i < cnt; i++) {
                if (vmem_xalloc(qc->qc_vmem, qc->qc_size, 0, 0, 0,
                    VMEM_ADDR_QCACHE_MIN, VMEM_ADDR_MAX, flags, &addr) != 0)
                        break;
                store[i] = (void *)addr;
        }
        return (i);
}

/*
 * Release memory from the UMA cache to the arena.
 */
static void
qc_release(void *arg, void **store, int cnt)
{
        qcache_t *qc;
        int i;

        qc = arg;
        for (i = 0; i < cnt; i++)
                vmem_xfree(qc->qc_vmem, (vmem_addr_t)store[i], qc->qc_size);
}

static void
qc_init(vmem_t *vm, vmem_size_t qcache_max)
{
        qcache_t *qc;
        vmem_size_t size;
        int qcache_idx_max;
        int i;

        MPASS((qcache_max & vm->vm_quantum_mask) == 0);
        qcache_idx_max = MIN(qcache_max >> vm->vm_quantum_shift,
            VMEM_QCACHE_IDX_MAX);
        vm->vm_qcache_max = qcache_idx_max << vm->vm_quantum_shift;
        for (i = 0; i < qcache_idx_max; i++) {
                qc = &vm->vm_qcache[i];
                size = (i + 1) << vm->vm_quantum_shift;
                snprintf(qc->qc_name, sizeof(qc->qc_name), "%s-%zu",
                    vm->vm_name, size);
                qc->qc_vmem = vm;
                qc->qc_size = size;
                qc->qc_cache = uma_zcache_create(qc->qc_name, size,
                    NULL, NULL, NULL, NULL, qc_import, qc_release, qc, 0);
                MPASS(qc->qc_cache);
        }
}

static void
qc_destroy(vmem_t *vm)
{
        int qcache_idx_max;
        int i;

        qcache_idx_max = vm->vm_qcache_max >> vm->vm_quantum_shift;
        for (i = 0; i < qcache_idx_max; i++)
                uma_zdestroy(vm->vm_qcache[i].qc_cache);
}

static void
qc_drain(vmem_t *vm)
{
        int qcache_idx_max;
        int i;

        qcache_idx_max = vm->vm_qcache_max >> vm->vm_quantum_shift;
        for (i = 0; i < qcache_idx_max; i++)
                uma_zone_reclaim(vm->vm_qcache[i].qc_cache, UMA_RECLAIM_DRAIN);
}

#ifndef UMA_USE_DMAP

static struct mtx_padalign __exclusive_cache_line vmem_bt_lock;

/*
 * vmem_bt_alloc:  Allocate a new page of boundary tags.
 *
 * On architectures with UMA_USE_DMAP there is no recursion; no address
 * space need be allocated to allocate boundary tags.  For the others, we
 * must handle recursion.  Boundary tags are necessary to allocate new
 * boundary tags.
 *
 * UMA guarantees that enough tags are held in reserve to allocate a new
 * page of kva.  We dip into this reserve by specifying M_USE_RESERVE only
 * when allocating the page to hold new boundary tags.  In this way the
 * reserve is automatically filled by the allocation that uses the reserve.
 * 
 * We still have to guarantee that the new tags are allocated atomically since
 * many threads may try concurrently.  The bt_lock provides this guarantee.
 * We convert WAITOK allocations to NOWAIT and then handle the blocking here
 * on failure.  It's ok to return NULL for a WAITOK allocation as UMA will
 * loop again after checking to see if we lost the race to allocate.
 *
 * There is a small race between vmem_bt_alloc() returning the page and the
 * zone lock being acquired to add the page to the zone.  For WAITOK
 * allocations we just pause briefly.  NOWAIT may experience a transient
 * failure.  To alleviate this we permit a small number of simultaneous
 * fills to proceed concurrently so NOWAIT is less likely to fail unless
 * we are really out of KVA.
 */
static void *
vmem_bt_alloc(uma_zone_t zone, vm_size_t bytes, int domain, uint8_t *pflag,
    int wait)
{
        vmem_addr_t addr;

        *pflag = UMA_SLAB_KERNEL;

        /*
         * Single thread boundary tag allocation so that the address space
         * and memory are added in one atomic operation.
         */
        mtx_lock(&vmem_bt_lock);
        if (vmem_xalloc(vm_dom[domain].vmd_kernel_arena, bytes, 0, 0, 0,
            VMEM_ADDR_MIN, VMEM_ADDR_MAX,
            M_NOWAIT | M_NOVM | M_USE_RESERVE | M_BESTFIT, &addr) == 0) {
                if (kmem_back_domain(domain, kernel_object, addr, bytes,
                    M_NOWAIT | M_USE_RESERVE) == 0) {
                        mtx_unlock(&vmem_bt_lock);
                        return ((void *)addr);
                }
                vmem_xfree(vm_dom[domain].vmd_kernel_arena, addr, bytes);
                mtx_unlock(&vmem_bt_lock);
                /*
                 * Out of memory, not address space.  This may not even be
                 * possible due to M_USE_RESERVE page allocation.
                 */
                if (wait & M_WAITOK)
                        vm_wait_domain(domain);
                return (NULL);
        }
        mtx_unlock(&vmem_bt_lock);
        /*
         * We're either out of address space or lost a fill race.
         */
        if (wait & M_WAITOK)
                pause("btalloc", 1);

        return (NULL);
}
#endif

void
vmem_startup(void)
{

        mtx_init(&vmem_list_lock, "vmem list lock", NULL, MTX_DEF);
        vmem_zone = uma_zcreate("vmem",
            sizeof(struct vmem), NULL, NULL, NULL, NULL,
            UMA_ALIGN_PTR, 0);
        vmem_bt_zone = uma_zcreate("vmem btag",
            sizeof(struct vmem_btag), NULL, NULL, NULL, NULL,
            UMA_ALIGN_PTR, UMA_ZONE_VM);
#ifndef UMA_USE_DMAP
        mtx_init(&vmem_bt_lock, "btag lock", NULL, MTX_DEF);
        uma_prealloc(vmem_bt_zone, BT_MAXALLOC);
        /*
         * Reserve enough tags to allocate new tags.  We allow multiple
         * CPUs to attempt to allocate new tags concurrently to limit
         * false restarts in UMA.  vmem_bt_alloc() allocates from a per-domain
         * arena, which may involve importing a range from the kernel arena,
         * so we need to keep at least 2 * BT_MAXALLOC tags reserved.
         */
        uma_zone_reserve(vmem_bt_zone, 2 * BT_MAXALLOC * mp_ncpus);
        uma_zone_set_allocf(vmem_bt_zone, vmem_bt_alloc);
#endif
}

static int
vmem_rehash(vmem_t *vm, vmem_size_t newhashsize)
{
        bt_t *bt;
        struct vmem_hashlist *newhashlist;
        struct vmem_hashlist *oldhashlist;
        vmem_size_t i, oldhashsize;

        MPASS(newhashsize > 0);

        newhashlist = malloc(sizeof(struct vmem_hashlist) * newhashsize,
            M_VMEM, M_NOWAIT);
        if (newhashlist == NULL)
                return ENOMEM;
        for (i = 0; i < newhashsize; i++) {
                LIST_INIT(&newhashlist[i]);
        }

        VMEM_LOCK(vm);
        oldhashlist = vm->vm_hashlist;
        oldhashsize = vm->vm_hashsize;
        vm->vm_hashlist = newhashlist;
        vm->vm_hashsize = newhashsize;
        if (oldhashlist == NULL) {
                VMEM_UNLOCK(vm);
                return 0;
        }
        for (i = 0; i < oldhashsize; i++) {
                while ((bt = LIST_FIRST(&oldhashlist[i])) != NULL) {
                        bt_rembusy(vm, bt);
                        bt_insbusy(vm, bt);
                }
        }
        VMEM_UNLOCK(vm);

        if (oldhashlist != vm->vm_hash0)
                free(oldhashlist, M_VMEM);

        return 0;
}

static void
vmem_periodic_kick(void *dummy)
{

        taskqueue_enqueue(taskqueue_thread, &vmem_periodic_wk);
}

static void
vmem_periodic(void *unused, int pending)
{
        vmem_t *vm;
        vmem_size_t desired;
        vmem_size_t current;

        VMEM_LIST_LOCK();
        LIST_FOREACH(vm, &vmem_list, vm_alllist) {
#ifdef DIAGNOSTIC
                /* Convenient time to verify vmem state. */
                if (enable_vmem_check == 1) {
                        VMEM_LOCK(vm);
                        vmem_check(vm);
                        VMEM_UNLOCK(vm);
                }
#endif
                desired = 1 << flsl(vm->vm_nbusytag);
                desired = MIN(MAX(desired, VMEM_HASHSIZE_MIN),
                    VMEM_HASHSIZE_MAX);
                current = vm->vm_hashsize;

                /* Grow in powers of two.  Shrink less aggressively. */
                if (desired >= current * 2 || desired * 4 <= current)
                        vmem_rehash(vm, desired);

                /*
                 * Periodically wake up threads waiting for resources,
                 * so they could ask for reclamation again.
                 */
                VMEM_CONDVAR_BROADCAST(vm);
        }
        VMEM_LIST_UNLOCK();

        callout_reset(&vmem_periodic_ch, vmem_periodic_interval,
            vmem_periodic_kick, NULL);
}

static void
vmem_start_callout(void *unused)
{

        TASK_INIT(&vmem_periodic_wk, 0, vmem_periodic, NULL);
        vmem_periodic_interval = hz * 10;
        callout_init(&vmem_periodic_ch, 1);
        callout_reset(&vmem_periodic_ch, vmem_periodic_interval,
            vmem_periodic_kick, NULL);
}
SYSINIT(vfs, SI_SUB_CONFIGURE, SI_ORDER_ANY, vmem_start_callout, NULL);
#endif  /* _KERNEL */

static void
vmem_add1(vmem_t *vm, vmem_addr_t addr, vmem_size_t size, int type)
{
        bt_t *btfree, *btprev, *btspan;

        VMEM_ASSERT_LOCKED(vm);
        MPASS(type == BT_TYPE_SPAN || type == BT_TYPE_SPAN_STATIC);
        MPASS((size & vm->vm_quantum_mask) == 0);

        if (vm->vm_releasefn == NULL) {
                /*
                 * The new segment will never be released, so see if it is
                 * contiguous with respect to an existing segment.  In this case
                 * a span tag is not needed, and it may be possible now or in
                 * the future to coalesce the new segment with an existing free
                 * segment.
                 */
                btprev = TAILQ_LAST(&vm->vm_seglist, vmem_seglist);
                if ((!bt_isbusy(btprev) && !bt_isfree(btprev)) ||
                    btprev->bt_start + btprev->bt_size != addr)
                        btprev = NULL;
        } else {
                btprev = NULL;
        }

        if (btprev == NULL || bt_isbusy(btprev)) {
                if (btprev == NULL) {
                        btspan = bt_alloc(vm);
                        btspan->bt_type = type;
                        btspan->bt_start = addr;
                        btspan->bt_size = size;
                        bt_insseg_tail(vm, btspan);
                }

                btfree = bt_alloc(vm);
                btfree->bt_type = BT_TYPE_FREE;
                btfree->bt_start = addr;
                btfree->bt_size = size;
                bt_insseg_tail(vm, btfree);
                bt_insfree(vm, btfree);
        } else {
                bt_remfree(vm, btprev);
                btprev->bt_size += size;
                bt_insfree(vm, btprev);
        }

        vm->vm_size += size;
}

static void
vmem_destroy1(vmem_t *vm)
{
        bt_t *bt;

#ifdef  _KERNEL
        /*
         * Drain per-cpu quantum caches.
         */
        qc_destroy(vm);
#endif

        /*
         * The vmem should now only contain empty segments.
         */
        VMEM_LOCK(vm);
        MPASS(vm->vm_nbusytag == 0);

        TAILQ_REMOVE(&vm->vm_seglist, &vm->vm_cursor, bt_seglist);
        while ((bt = TAILQ_FIRST(&vm->vm_seglist)) != NULL)
                bt_remseg(vm, bt);

        if (vm->vm_hashlist != NULL && vm->vm_hashlist != vm->vm_hash0) {
#ifdef _KERNEL
                free(vm->vm_hashlist, M_VMEM);
#else
                free(vm->vm_hashlist);
#endif
        }

        bt_freetrim(vm, 0);

        VMEM_CONDVAR_DESTROY(vm);
        VMEM_LOCK_DESTROY(vm);
#ifdef _KERNEL
        uma_zfree(vmem_zone, vm);
#else
        free(vm);
#endif
}

static int
vmem_import(vmem_t *vm, vmem_size_t size, vmem_size_t align, int flags)
{
        vmem_addr_t addr;
        int error;

        if (vm->vm_importfn == NULL)
                return (EINVAL);

        /*
         * To make sure we get a span that meets the alignment we double it
         * and add the size to the tail.  This slightly overestimates.
         */
        if (align != vm->vm_quantum_mask + 1)
                size = (align * 2) + size;
        size = roundup(size, vm->vm_import_quantum);

        if (vm->vm_limit != 0 && vm->vm_limit < vm->vm_size + size)
                return (ENOMEM);

        bt_save(vm);
        VMEM_UNLOCK(vm);
        error = (vm->vm_importfn)(vm->vm_arg, size, flags, &addr);
        VMEM_LOCK(vm);
        bt_restore(vm);
        if (error)
                return (ENOMEM);

        vmem_add1(vm, addr, size, BT_TYPE_SPAN);

        return 0;
}

/*
 * vmem_fit: check if a bt can satisfy the given restrictions.
 *
 * it's a caller's responsibility to ensure the region is big enough
 * before calling us.
 */
static int
vmem_fit(const bt_t *bt, vmem_size_t size, vmem_size_t align,
    vmem_size_t phase, vmem_size_t nocross, vmem_addr_t minaddr,
    vmem_addr_t maxaddr, vmem_addr_t *addrp)
{
        vmem_addr_t start;
        vmem_addr_t end;

        MPASS(size > 0);
        MPASS(bt->bt_size >= size); /* caller's responsibility */

        /*
         * XXX assumption: vmem_addr_t and vmem_size_t are
         * unsigned integer of the same size.
         */

        start = bt->bt_start;
        if (start < minaddr) {
                start = minaddr;
        }
        end = BT_END(bt);
        if (end > maxaddr)
                end = maxaddr;
        if (start > end) 
                return (ENOMEM);

        start = VMEM_ALIGNUP(start - phase, align) + phase;
        if (start < bt->bt_start)
                start += align;
        if (VMEM_CROSS_P(start, start + size - 1, nocross)) {
                MPASS(align < nocross);
                start = VMEM_ALIGNUP(start - phase, nocross) + phase;
        }
        if (start <= end && end - start >= size - 1) {
                MPASS((start & (align - 1)) == phase);
                MPASS(!VMEM_CROSS_P(start, start + size - 1, nocross));
                MPASS(minaddr <= start);
                MPASS(maxaddr == 0 || start + size - 1 <= maxaddr);
                MPASS(bt->bt_start <= start);
                MPASS(BT_END(bt) - start >= size - 1);
                *addrp = start;

                return (0);
        }
        return (ENOMEM);
}

/*
 * vmem_clip:  Trim the boundary tag edges to the requested start and size.
 */
static void
vmem_clip(vmem_t *vm, bt_t *bt, vmem_addr_t start, vmem_size_t size)
{
        bt_t *btnew;
        bt_t *btprev;

        VMEM_ASSERT_LOCKED(vm);
        MPASS(bt->bt_type == BT_TYPE_FREE);
        MPASS(bt->bt_size >= size);
        bt_remfree(vm, bt);
        if (bt->bt_start != start) {
                btprev = bt_alloc(vm);
                btprev->bt_type = BT_TYPE_FREE;
                btprev->bt_start = bt->bt_start;
                btprev->bt_size = start - bt->bt_start;
                bt->bt_start = start;
                bt->bt_size -= btprev->bt_size;
                bt_insfree(vm, btprev);
                bt_insseg(vm, btprev,
                    TAILQ_PREV(bt, vmem_seglist, bt_seglist));
        }
        MPASS(bt->bt_start == start);
        if (bt->bt_size != size && bt->bt_size - size > vm->vm_quantum_mask) {
                /* split */
                btnew = bt_alloc(vm);
                btnew->bt_type = BT_TYPE_BUSY;
                btnew->bt_start = bt->bt_start;
                btnew->bt_size = size;
                bt->bt_start = bt->bt_start + size;
                bt->bt_size -= size;
                bt_insfree(vm, bt);
                bt_insseg(vm, btnew,
                    TAILQ_PREV(bt, vmem_seglist, bt_seglist));
                bt_insbusy(vm, btnew);
                bt = btnew;
        } else {
                bt->bt_type = BT_TYPE_BUSY;
                bt_insbusy(vm, bt);
        }
        MPASS(bt->bt_size >= size);
}

static int
vmem_try_fetch(vmem_t *vm, const vmem_size_t size, vmem_size_t align, int flags)
{
        vmem_size_t avail;

        VMEM_ASSERT_LOCKED(vm);

        /*
         * XXX it is possible to fail to meet xalloc constraints with the
         * imported region.  It is up to the user to specify the
         * import quantum such that it can satisfy any allocation.
         */
        if (vmem_import(vm, size, align, flags) == 0)
                return (1);

        /*
         * Try to free some space from the quantum cache or reclaim
         * functions if available.
         */
        if (vm->vm_qcache_max != 0 || vm->vm_reclaimfn != NULL) {
                avail = vm->vm_size - vm->vm_inuse;
                bt_save(vm);
                VMEM_UNLOCK(vm);
#ifdef _KERNEL
                if (vm->vm_qcache_max != 0)
                        qc_drain(vm);
#endif
                if (vm->vm_reclaimfn != NULL)
                        vm->vm_reclaimfn(vm, flags);
                VMEM_LOCK(vm);
                bt_restore(vm);
                /* If we were successful retry even NOWAIT. */
                if (vm->vm_size - vm->vm_inuse > avail)
                        return (1);
        }
        if ((flags & M_NOWAIT) != 0)
                return (0);
        bt_save(vm);
        VMEM_CONDVAR_WAIT(vm);
        bt_restore(vm);
        return (1);
}

static int
vmem_try_release(vmem_t *vm, struct vmem_btag *bt, const bool remfree)
{
        struct vmem_btag *prev;

        MPASS(bt->bt_type == BT_TYPE_FREE);

        if (vm->vm_releasefn == NULL)
                return (0);

        prev = TAILQ_PREV(bt, vmem_seglist, bt_seglist);
        MPASS(prev != NULL);
        MPASS(prev->bt_type != BT_TYPE_FREE);

        if (prev->bt_type == BT_TYPE_SPAN && prev->bt_size == bt->bt_size) {
                vmem_addr_t spanaddr;
                vmem_size_t spansize;

                MPASS(prev->bt_start == bt->bt_start);
                spanaddr = prev->bt_start;
                spansize = prev->bt_size;
                if (remfree)
                        bt_remfree(vm, bt);
                bt_remseg(vm, bt);
                bt_remseg(vm, prev);
                vm->vm_size -= spansize;
                VMEM_CONDVAR_BROADCAST(vm);
                bt_freetrim(vm, BT_MAXFREE);
                vm->vm_releasefn(vm->vm_arg, spanaddr, spansize);
                return (1);
        }
        return (0);
}

static int
vmem_xalloc_nextfit(vmem_t *vm, const vmem_size_t size, vmem_size_t align,
    const vmem_size_t phase, const vmem_size_t nocross, int flags,
    vmem_addr_t *addrp)
{
        struct vmem_btag *bt, *cursor, *next, *prev;
        int error;

        error = ENOMEM;
        VMEM_LOCK(vm);

        /*
         * Make sure we have enough tags to complete the operation.
         */
        if (bt_fill(vm, flags) != 0)
                goto out;

retry:
        /*
         * Find the next free tag meeting our constraints.  If one is found,
         * perform the allocation.
         */
        for (cursor = &vm->vm_cursor, bt = TAILQ_NEXT(cursor, bt_seglist);
            bt != cursor; bt = TAILQ_NEXT(bt, bt_seglist)) {
                if (bt == NULL)
                        bt = TAILQ_FIRST(&vm->vm_seglist);
                if (bt->bt_type == BT_TYPE_FREE && bt->bt_size >= size &&
                    (error = vmem_fit(bt, size, align, phase, nocross,
                    VMEM_ADDR_MIN, VMEM_ADDR_MAX, addrp)) == 0) {
                        vmem_clip(vm, bt, *addrp, size);
                        break;
                }
        }

        /*
         * Try to coalesce free segments around the cursor.  If we succeed, and
         * have not yet satisfied the allocation request, try again with the
         * newly coalesced segment.
         */
        if ((next = TAILQ_NEXT(cursor, bt_seglist)) != NULL &&
            (prev = TAILQ_PREV(cursor, vmem_seglist, bt_seglist)) != NULL &&
            next->bt_type == BT_TYPE_FREE && prev->bt_type == BT_TYPE_FREE &&
            prev->bt_start + prev->bt_size == next->bt_start) {
                prev->bt_size += next->bt_size;
                bt_remfree(vm, next);
                bt_remseg(vm, next);

                /*
                 * The coalesced segment might be able to satisfy our request.
                 * If not, we might need to release it from the arena.
                 */
                if (error == ENOMEM && prev->bt_size >= size &&
                    (error = vmem_fit(prev, size, align, phase, nocross,
                    VMEM_ADDR_MIN, VMEM_ADDR_MAX, addrp)) == 0) {
                        vmem_clip(vm, prev, *addrp, size);
                        bt = prev;
                } else
                        (void)vmem_try_release(vm, prev, true);
        }

        /*
         * If the allocation was successful, advance the cursor.
         */
        if (error == 0) {
                TAILQ_REMOVE(&vm->vm_seglist, cursor, bt_seglist);
                for (; bt != NULL && bt->bt_start < *addrp + size;
                    bt = TAILQ_NEXT(bt, bt_seglist))
                        ;
                if (bt != NULL)
                        TAILQ_INSERT_BEFORE(bt, cursor, bt_seglist);
                else
                        TAILQ_INSERT_HEAD(&vm->vm_seglist, cursor, bt_seglist);
        }

        /*
         * Attempt to bring additional resources into the arena.  If that fails
         * and M_WAITOK is specified, sleep waiting for resources to be freed.
         */
        if (error == ENOMEM && vmem_try_fetch(vm, size, align, flags))
                goto retry;

out:
        VMEM_UNLOCK(vm);
        return (error);
}

/* ---- vmem API */

void
vmem_set_import(vmem_t *vm, vmem_import_t *importfn,
     vmem_release_t *releasefn, void *arg, vmem_size_t import_quantum)
{

        VMEM_LOCK(vm);
        KASSERT(vm->vm_size == 0, ("%s: arena is non-empty", __func__));
        vm->vm_importfn = importfn;
        vm->vm_releasefn = releasefn;
        vm->vm_arg = arg;
        vm->vm_import_quantum = import_quantum;
        VMEM_UNLOCK(vm);
}

void
vmem_set_limit(vmem_t *vm, vmem_size_t limit)
{

        VMEM_LOCK(vm);
        vm->vm_limit = limit;
        VMEM_UNLOCK(vm);
}

void
vmem_set_reclaim(vmem_t *vm, vmem_reclaim_t *reclaimfn)
{

        VMEM_LOCK(vm);
        vm->vm_reclaimfn = reclaimfn;
        VMEM_UNLOCK(vm);
}

/*
 * vmem_init: Initializes vmem arena.
 */
vmem_t *
vmem_init(vmem_t *vm, const char *name, vmem_addr_t base, vmem_size_t size,
    vmem_size_t quantum, vmem_size_t qcache_max, int flags)
{
        vmem_size_t i;

#ifdef _KERNEL
        MPASS(quantum > 0);
        MPASS((quantum & (quantum - 1)) == 0);
#else
        assert(quantum == 0);
        assert(qcache_max == 0);
        quantum = 1;
#endif

        bzero(vm, sizeof(*vm));

        VMEM_CONDVAR_INIT(vm, name);
        VMEM_LOCK_INIT(vm, name);
        vm->vm_nfreetags = 0;
        LIST_INIT(&vm->vm_freetags);
        strlcpy(vm->vm_name, name, sizeof(vm->vm_name));
        vm->vm_quantum_mask = quantum - 1;
        vm->vm_quantum_shift = flsl(quantum) - 1;
        vm->vm_nbusytag = 0;
        vm->vm_size = 0;
        vm->vm_limit = 0;
        vm->vm_inuse = 0;
#ifdef _KERNEL
        qc_init(vm, qcache_max);
#else
        (void)qcache_max;
#endif

        TAILQ_INIT(&vm->vm_seglist);
        vm->vm_cursor.bt_start = vm->vm_cursor.bt_size = 0;
        vm->vm_cursor.bt_type = BT_TYPE_CURSOR;
        TAILQ_INSERT_TAIL(&vm->vm_seglist, &vm->vm_cursor, bt_seglist);

        for (i = 0; i < VMEM_MAXORDER; i++)
                LIST_INIT(&vm->vm_freelist[i]);

        memset(&vm->vm_hash0, 0, sizeof(vm->vm_hash0));
        vm->vm_hashsize = VMEM_HASHSIZE_MIN;
        vm->vm_hashlist = vm->vm_hash0;

        if (size != 0) {
                if (vmem_add(vm, base, size, flags) != 0) {
                        vmem_destroy1(vm);
                        return NULL;
                }
        }

        VMEM_LIST_LOCK();
        LIST_INSERT_HEAD(&vmem_list, vm, vm_alllist);
        VMEM_LIST_UNLOCK();

        return vm;
}

/*
 * vmem_create: create an arena.
 */
vmem_t *
vmem_create(const char *name, vmem_addr_t base, vmem_size_t size,
    vmem_size_t quantum, vmem_size_t qcache_max, int flags)
{

        vmem_t *vm;

#ifdef _KERNEL
        vm = uma_zalloc(vmem_zone, flags & (M_WAITOK|M_NOWAIT));
#else
        assert(quantum == 0);
        assert(qcache_max == 0);
        vm = malloc(sizeof(vmem_t));
#endif
        if (vm == NULL)
                return (NULL);
        if (vmem_init(vm, name, base, size, quantum, qcache_max,
            flags) == NULL)
                return (NULL);
        return (vm);
}

void
vmem_destroy(vmem_t *vm)
{
        VMEM_LIST_LOCK();
        LIST_REMOVE(vm, vm_alllist);
        VMEM_LIST_UNLOCK();

        vmem_destroy1(vm);
}

vmem_size_t
vmem_roundup_size(vmem_t *vm, vmem_size_t size)
{

        return (size + vm->vm_quantum_mask) & ~vm->vm_quantum_mask;
}

/*
 * vmem_alloc: allocate resource from the arena.
 */
int
vmem_alloc(vmem_t *vm, vmem_size_t size, int flags, vmem_addr_t *addrp)
{
        const int strat __unused = flags & VMEM_FITMASK;

        flags &= VMEM_FLAGS;
        MPASS(size > 0);
        MPASS(strat == M_BESTFIT || strat == M_FIRSTFIT || strat == M_NEXTFIT);
        if ((flags & M_NOWAIT) == 0)
                WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "vmem_alloc");

#ifdef _KERNEL
        if (size <= vm->vm_qcache_max) {
                qcache_t *qc;

                /*
                 * Resource 0 cannot be cached, so avoid a blocking allocation
                 * in qc_import() and give the vmem_xalloc() call below a chance
                 * to return 0.
                 */
                qc = &vm->vm_qcache[(size - 1) >> vm->vm_quantum_shift];
                *addrp = (vmem_addr_t)uma_zalloc(qc->qc_cache,
                    (flags & ~M_WAITOK) | M_NOWAIT);
                if (__predict_true(*addrp != 0))
                        return (0);
        }
#endif

        return (vmem_xalloc(vm, size, 0, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX,
            flags, addrp));
}

int
vmem_xalloc(vmem_t *vm, const vmem_size_t size0, vmem_size_t align,
    const vmem_size_t phase, const vmem_size_t nocross,
    const vmem_addr_t minaddr, const vmem_addr_t maxaddr, int flags,
    vmem_addr_t *addrp)
{
        const vmem_size_t size = vmem_roundup_size(vm, size0);
        struct vmem_freelist *list;
        struct vmem_freelist *first;
        struct vmem_freelist *end;
        bt_t *bt;
        int error;
        int strat;

        flags &= VMEM_FLAGS;
        strat = flags & VMEM_FITMASK;
        MPASS(size0 > 0);
        MPASS(size > 0);
        MPASS(strat == M_BESTFIT || strat == M_FIRSTFIT || strat == M_NEXTFIT);
        MPASS((flags & (M_NOWAIT|M_WAITOK)) != (M_NOWAIT|M_WAITOK));
        if ((flags & M_NOWAIT) == 0)
                WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, "vmem_xalloc");
        MPASS((align & vm->vm_quantum_mask) == 0);
        MPASS((align & (align - 1)) == 0);
        MPASS((phase & vm->vm_quantum_mask) == 0);
        MPASS((nocross & vm->vm_quantum_mask) == 0);
        MPASS((nocross & (nocross - 1)) == 0);
        MPASS((align == 0 && phase == 0) || phase < align);
        MPASS(nocross == 0 || nocross >= size);
        MPASS(minaddr <= maxaddr);
        MPASS(!VMEM_CROSS_P(phase, phase + size - 1, nocross));
        if (strat == M_NEXTFIT)
                MPASS(minaddr == VMEM_ADDR_MIN && maxaddr == VMEM_ADDR_MAX);

        if (align == 0)
                align = vm->vm_quantum_mask + 1;
        *addrp = 0;

        /*
         * Next-fit allocations don't use the freelists.
         */
        if (strat == M_NEXTFIT)
                return (vmem_xalloc_nextfit(vm, size0, align, phase, nocross,
                    flags, addrp));

        end = &vm->vm_freelist[VMEM_MAXORDER];
        /*
         * choose a free block from which we allocate.
         */
        first = bt_freehead_toalloc(vm, size, strat);
        VMEM_LOCK(vm);

        /*
         * Make sure we have enough tags to complete the operation.
         */
        error = bt_fill(vm, flags);
        if (error != 0)
                goto out;
        for (;;) {
                /*
                 * Scan freelists looking for a tag that satisfies the
                 * allocation.  If we're doing BESTFIT we may encounter
                 * sizes below the request.  If we're doing FIRSTFIT we
                 * inspect only the first element from each list.
                 */
                for (list = first; list < end; list++) {
                        LIST_FOREACH(bt, list, bt_freelist) {
                                if (bt->bt_size >= size) {
                                        error = vmem_fit(bt, size, align, phase,
                                            nocross, minaddr, maxaddr, addrp);
                                        if (error == 0) {
                                                vmem_clip(vm, bt, *addrp, size);
                                                goto out;
                                        }
                                }
                                /* FIRST skips to the next list. */
                                if (strat == M_FIRSTFIT)
                                        break;
                        }
                }

                /*
                 * Retry if the fast algorithm failed.
                 */
                if (strat == M_FIRSTFIT) {
                        strat = M_BESTFIT;
                        first = bt_freehead_toalloc(vm, size, strat);
                        continue;
                }

                /*
                 * Try a few measures to bring additional resources into the
                 * arena.  If all else fails, we will sleep waiting for
                 * resources to be freed.
                 */
                if (!vmem_try_fetch(vm, size, align, flags)) {
                        error = ENOMEM;
                        break;
                }
        }
out:
        VMEM_UNLOCK(vm);
        if (error != 0 && (flags & M_NOWAIT) == 0)
                panic("failed to allocate waiting allocation\n");

        return (error);
}

/*
 * vmem_free: free the resource to the arena.
 */
void
vmem_free(vmem_t *vm, vmem_addr_t addr, vmem_size_t size)
{
        MPASS(size > 0);

#ifdef _KERNEL
        if (size <= vm->vm_qcache_max &&
            __predict_true(addr >= VMEM_ADDR_QCACHE_MIN)) {
                qcache_t *qc;

                qc = &vm->vm_qcache[(size - 1) >> vm->vm_quantum_shift];
                uma_zfree(qc->qc_cache, (void *)addr);
        } else
#endif
                vmem_xfree(vm, addr, size);
}

void
vmem_xfree(vmem_t *vm, vmem_addr_t addr, vmem_size_t size __unused)
{
        bt_t *bt;
        bt_t *t;

        MPASS(size > 0);

        VMEM_LOCK(vm);
        bt = bt_lookupbusy(vm, addr);
        MPASS(bt != NULL);
        MPASS(bt->bt_start == addr);
        MPASS(bt->bt_size == vmem_roundup_size(vm, size) ||
            bt->bt_size - vmem_roundup_size(vm, size) <= vm->vm_quantum_mask);
        MPASS(bt->bt_type == BT_TYPE_BUSY);
        bt_rembusy(vm, bt);
        bt->bt_type = BT_TYPE_FREE;

        /* coalesce */
        t = TAILQ_NEXT(bt, bt_seglist);
        if (t != NULL && t->bt_type == BT_TYPE_FREE) {
                MPASS(BT_END(bt) < t->bt_start);        /* YYY */
                bt->bt_size += t->bt_size;
                bt_remfree(vm, t);
                bt_remseg(vm, t);
        }
        t = TAILQ_PREV(bt, vmem_seglist, bt_seglist);
        if (t != NULL && t->bt_type == BT_TYPE_FREE) {
                MPASS(BT_END(t) < bt->bt_start);        /* YYY */
                bt->bt_size += t->bt_size;
                bt->bt_start = t->bt_start;
                bt_remfree(vm, t);
                bt_remseg(vm, t);
        }

        if (!vmem_try_release(vm, bt, false)) {
                bt_insfree(vm, bt);
                VMEM_CONDVAR_BROADCAST(vm);
                bt_freetrim(vm, BT_MAXFREE);
        }
}

/*
 * vmem_add:
 *
 */
int
vmem_add(vmem_t *vm, vmem_addr_t addr, vmem_size_t size, int flags)
{
        int error;

        flags &= VMEM_FLAGS;

        VMEM_LOCK(vm);
        error = bt_fill(vm, flags);
        if (error == 0)
                vmem_add1(vm, addr, size, BT_TYPE_SPAN_STATIC);
        VMEM_UNLOCK(vm);

        return (error);
}

/*
 * vmem_size: information about arenas size
 */
vmem_size_t
vmem_size(vmem_t *vm, int typemask)
{
        int i;

        switch (typemask) {
        case VMEM_ALLOC:
                return vm->vm_inuse;
        case VMEM_FREE:
                return vm->vm_size - vm->vm_inuse;
        case VMEM_FREE|VMEM_ALLOC:
                return vm->vm_size;
        case VMEM_MAXFREE:
                VMEM_LOCK(vm);
                for (i = VMEM_MAXORDER - 1; i >= 0; i--) {
                        if (LIST_EMPTY(&vm->vm_freelist[i]))
                                continue;
                        VMEM_UNLOCK(vm);
                        return ((vmem_size_t)ORDER2SIZE(i) <<
                            vm->vm_quantum_shift);
                }
                VMEM_UNLOCK(vm);
                return (0);
        default:
                panic("vmem_size");
                return (0);
        }
}

/* ---- debug */

#ifdef _KERNEL
#if defined(DDB) || defined(DIAGNOSTIC)

static void bt_dump(const bt_t *, int (*)(const char *, ...)
    __printflike(1, 2));

static const char *
bt_type_string(int type)
{

        switch (type) {
        case BT_TYPE_BUSY:
                return "busy";
        case BT_TYPE_FREE:
                return "free";
        case BT_TYPE_SPAN:
                return "span";
        case BT_TYPE_SPAN_STATIC:
                return "static span";
        case BT_TYPE_CURSOR:
                return "cursor";
        default:
                break;
        }
        return "BOGUS";
}

static void
bt_dump(const bt_t *bt, int (*pr)(const char *, ...))
{

        (*pr)("\t%p: %jx %jx, %d(%s)\n",
            bt, (intmax_t)bt->bt_start, (intmax_t)bt->bt_size,
            bt->bt_type, bt_type_string(bt->bt_type));
}

static void
vmem_dump(const vmem_t *vm , int (*pr)(const char *, ...) __printflike(1, 2))
{
        const bt_t *bt;
        int i;

        (*pr)("vmem %p '%s'\n", vm, vm->vm_name);
        TAILQ_FOREACH(bt, &vm->vm_seglist, bt_seglist) {
                bt_dump(bt, pr);
        }

        for (i = 0; i < VMEM_MAXORDER; i++) {
                const struct vmem_freelist *fl = &vm->vm_freelist[i];

                if (LIST_EMPTY(fl)) {
                        continue;
                }

                (*pr)("freelist[%d]\n", i);
                LIST_FOREACH(bt, fl, bt_freelist) {
                        bt_dump(bt, pr);
                }
        }
}

#endif /* defined(DDB) || defined(DIAGNOSTIC) */

#if defined(DDB)
#include <ddb/ddb.h>

static bt_t *
vmem_whatis_lookup(vmem_t *vm, vmem_addr_t addr)
{
        bt_t *bt;

        TAILQ_FOREACH(bt, &vm->vm_seglist, bt_seglist) {
                if (BT_ISSPAN_P(bt)) {
                        continue;
                }
                if (bt->bt_start <= addr && addr <= BT_END(bt)) {
                        return bt;
                }
        }

        return NULL;
}

void
vmem_whatis(vmem_addr_t addr, int (*pr)(const char *, ...))
{
        vmem_t *vm;

        LIST_FOREACH(vm, &vmem_list, vm_alllist) {
                bt_t *bt;

                bt = vmem_whatis_lookup(vm, addr);
                if (bt == NULL) {
                        continue;
                }
                (*pr)("%p is %p+%zu in VMEM '%s' (%s)\n",
                    (void *)addr, (void *)bt->bt_start,
                    (vmem_size_t)(addr - bt->bt_start), vm->vm_name,
                    (bt->bt_type == BT_TYPE_BUSY) ? "allocated" : "free");
        }
}

void
vmem_printall(const char *modif, int (*pr)(const char *, ...))
{
        const vmem_t *vm;

        LIST_FOREACH(vm, &vmem_list, vm_alllist) {
                vmem_dump(vm, pr);
        }
}

void
vmem_print(vmem_addr_t addr, const char *modif, int (*pr)(const char *, ...))
{
        const vmem_t *vm = (const void *)addr;

        vmem_dump(vm, pr);
}

DB_SHOW_COMMAND(vmemdump, vmemdump)
{

        if (!have_addr) {
                db_printf("usage: show vmemdump <addr>\n");
                return;
        }

        vmem_dump((const vmem_t *)addr, db_printf);
}

DB_SHOW_ALL_COMMAND(vmemdump, vmemdumpall)
{
        const vmem_t *vm;

        LIST_FOREACH(vm, &vmem_list, vm_alllist)
                vmem_dump(vm, db_printf);
}

DB_SHOW_COMMAND(vmem, vmem_summ)
{
        const vmem_t *vm = (const void *)addr;
        const bt_t *bt;
        size_t ft[VMEM_MAXORDER], ut[VMEM_MAXORDER];
        size_t fs[VMEM_MAXORDER], us[VMEM_MAXORDER];
        int ord;

        if (!have_addr) {
                db_printf("usage: show vmem <addr>\n");
                return;
        }

        db_printf("vmem %p '%s'\n", vm, vm->vm_name);
        db_printf("\tquantum:\t%zu\n", vm->vm_quantum_mask + 1);
        db_printf("\tsize:\t%zu\n", vm->vm_size);
        db_printf("\tinuse:\t%zu\n", vm->vm_inuse);
        db_printf("\tfree:\t%zu\n", vm->vm_size - vm->vm_inuse);
        db_printf("\tbusy tags:\t%d\n", vm->vm_nbusytag);
        db_printf("\tfree tags:\t%d\n", vm->vm_nfreetags);

        memset(&ft, 0, sizeof(ft));
        memset(&ut, 0, sizeof(ut));
        memset(&fs, 0, sizeof(fs));
        memset(&us, 0, sizeof(us));
        TAILQ_FOREACH(bt, &vm->vm_seglist, bt_seglist) {
                ord = SIZE2ORDER(bt->bt_size >> vm->vm_quantum_shift);
                if (bt->bt_type == BT_TYPE_BUSY) {
                        ut[ord]++;
                        us[ord] += bt->bt_size;
                } else if (bt->bt_type == BT_TYPE_FREE) {
                        ft[ord]++;
                        fs[ord] += bt->bt_size;
                }
        }
        db_printf("\t\t\tinuse\tsize\t\tfree\tsize\n");
        for (ord = 0; ord < VMEM_MAXORDER; ord++) {
                if (ut[ord] == 0 && ft[ord] == 0)
                        continue;
                db_printf("\t%-15zu %zu\t%-15zu %zu\t%-16zu\n",
                    ORDER2SIZE(ord) << vm->vm_quantum_shift,
                    ut[ord], us[ord], ft[ord], fs[ord]);
        }
}

DB_SHOW_ALL_COMMAND(vmem, vmem_summall)
{
        const vmem_t *vm;

        LIST_FOREACH(vm, &vmem_list, vm_alllist)
                vmem_summ((db_expr_t)vm, TRUE, count, modif);
}
#endif /* defined(DDB) */

#define vmem_printf printf

#if defined(DIAGNOSTIC)

static bool
vmem_check_sanity(vmem_t *vm)
{
        const bt_t *bt, *bt2;

        MPASS(vm != NULL);

        TAILQ_FOREACH(bt, &vm->vm_seglist, bt_seglist) {
                if (bt->bt_start > BT_END(bt)) {
                        printf("corrupted tag\n");
                        bt_dump(bt, vmem_printf);
                        return false;
                }
        }
        TAILQ_FOREACH(bt, &vm->vm_seglist, bt_seglist) {
                if (bt->bt_type == BT_TYPE_CURSOR) {
                        if (bt->bt_start != 0 || bt->bt_size != 0) {
                                printf("corrupted cursor\n");
                                return false;
                        }
                        continue;
                }
                TAILQ_FOREACH(bt2, &vm->vm_seglist, bt_seglist) {
                        if (bt == bt2) {
                                continue;
                        }
                        if (bt2->bt_type == BT_TYPE_CURSOR) {
                                continue;
                        }
                        if (BT_ISSPAN_P(bt) != BT_ISSPAN_P(bt2)) {
                                continue;
                        }
                        if (bt->bt_start <= BT_END(bt2) &&
                            bt2->bt_start <= BT_END(bt)) {
                                printf("overwrapped tags\n");
                                bt_dump(bt, vmem_printf);
                                bt_dump(bt2, vmem_printf);
                                return false;
                        }
                }
        }

        return true;
}

static void
vmem_check(vmem_t *vm)
{

        if (!vmem_check_sanity(vm)) {
                panic("insanity vmem %p", vm);
        }
}

#endif /* defined(DIAGNOSTIC) */
#endif /* _KERNEL */