/*      $NetBSD: uvm_km.c,v 1.168 2026/06/28 03:31:31 kbowling Exp $    */

/*
 * Copyright (c) 1997 Charles D. Cranor and Washington University.
 * Copyright (c) 1991, 1993, The Regents of the University of California.
 *
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * The Mach Operating System project at Carnegie-Mellon University.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *      @(#)vm_kern.c   8.3 (Berkeley) 1/12/94
 * from: Id: uvm_km.c,v 1.1.2.14 1998/02/06 05:19:27 chs Exp
 *
 *
 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Permission to use, copy, modify and distribute this software and
 * its documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 *
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 *
 * Carnegie Mellon requests users of this software to return to
 *
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 *
 * any improvements or extensions that they make and grant Carnegie the
 * rights to redistribute these changes.
 */

/*
 * uvm_km.c: handle kernel memory allocation and management
 */

/*
 * overview of kernel memory management:
 *
 * the kernel virtual address space is mapped by "kernel_map."   kernel_map
 * starts at VM_MIN_KERNEL_ADDRESS and goes to VM_MAX_KERNEL_ADDRESS.
 * note that VM_MIN_KERNEL_ADDRESS is equal to vm_map_min(kernel_map).
 *
 * the kernel_map has several "submaps."   submaps can only appear in
 * the kernel_map (user processes can't use them).   submaps "take over"
 * the management of a sub-range of the kernel's address space.  submaps
 * are typically allocated at boot time and are never released.   kernel
 * virtual address space that is mapped by a submap is locked by the
 * submap's lock -- not the kernel_map's lock.
 *
 * thus, the useful feature of submaps is that they allow us to break
 * up the locking and protection of the kernel address space into smaller
 * chunks.
 *
 * the vm system has several standard kernel submaps/arenas, including:
 *   kmem_arena => used for kmem/pool (memoryallocators(9))
 *   pager_map => used to map "buf" structures into kernel space
 *   exec_map => used during exec to handle exec args
 *   etc...
 *
 * The kmem_arena is a "special submap", as it lives in a fixed map entry
 * within the kernel_map and is controlled by vmem(9).
 *
 * the kernel allocates its private memory out of special uvm_objects whose
 * reference count is set to UVM_OBJ_KERN (thus indicating that the objects
 * are "special" and never die).   all kernel objects should be thought of
 * as large, fixed-sized, sparsely populated uvm_objects.   each kernel
 * object is equal to the size of kernel virtual address space (i.e. the
 * value "VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS").
 *
 * note that just because a kernel object spans the entire kernel virtual
 * address space doesn't mean that it has to be mapped into the entire space.
 * large chunks of a kernel object's space go unused either because
 * that area of kernel VM is unmapped, or there is some other type of
 * object mapped into that range (e.g. a vnode).    for submap's kernel
 * objects, the only part of the object that can ever be populated is the
 * offsets that are managed by the submap.
 *
 * note that the "offset" in a kernel object is always the kernel virtual
 * address minus the VM_MIN_KERNEL_ADDRESS (aka vm_map_min(kernel_map)).
 * example:
 *   suppose VM_MIN_KERNEL_ADDRESS is 0xf8000000 and the kernel does a
 *   uvm_km_alloc(kernel_map, PAGE_SIZE) [allocate 1 wired down page in the
 *   kernel map].    if uvm_km_alloc returns virtual address 0xf8235000,
 *   then that means that the page at offset 0x235000 in kernel_object is
 *   mapped at 0xf8235000.
 *
 * kernel object have one other special property: when the kernel virtual
 * memory mapping them is unmapped, the backing memory in the object is
 * freed right away.   this is done with the uvm_km_pgremove() function.
 * this has to be done because there is no backing store for kernel pages
 * and no need to save them after they are no longer referenced.
 *
 * Generic arenas:
 *
 * kmem_arena:
 *      Main arena controlling the kernel KVA used by other arenas.
 *
 * kmem_va_arena:
 *      Implements quantum caching in order to speedup allocations and
 *      reduce fragmentation.  The pool(9), unless created with a custom
 *      meta-data allocator, and kmem(9) subsystems use this arena.
 *
 * Arenas for meta-data allocations are used by vmem(9) and pool(9).
 * These arenas cannot use quantum cache.  However, kmem_va_meta_arena
 * compensates this by importing larger chunks from kmem_arena.
 *
 * kmem_va_meta_arena:
 *      Space for meta-data.
 *
 * kmem_meta_arena:
 *      Imports from kmem_va_meta_arena.  Allocations from this arena are
 *      backed with the pages.
 *
 * Arena stacking:
 *
 *      kmem_arena
 *              kmem_va_arena
 *              kmem_va_meta_arena
 *                      kmem_meta_arena
 */

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: uvm_km.c,v 1.168 2026/06/28 03:31:31 kbowling Exp $");

#include "opt_uvmhist.h"

#include "opt_kmempages.h"

#ifndef NKMEMPAGES
#define NKMEMPAGES 0
#endif

/*
 * Defaults for lower and upper-bounds for the kmem_arena page count.
 * Can be overridden by kernel config options.
 */
#ifndef NKMEMPAGES_MIN
#define NKMEMPAGES_MIN NKMEMPAGES_MIN_DEFAULT
#endif

#ifndef NKMEMPAGES_MAX
#define NKMEMPAGES_MAX NKMEMPAGES_MAX_DEFAULT
#endif


#include <sys/param.h>
#include <sys/systm.h>
#include <sys/atomic.h>
#include <sys/proc.h>
#include <sys/pool.h>
#include <sys/vmem.h>
#include <sys/vmem_impl.h>
#include <sys/kmem.h>
#include <sys/msan.h>

#include <uvm/uvm.h>

/*
 * global data structures
 */

struct vm_map *kernel_map = NULL;

/*
 * local data structures
 */

static struct vm_map            kernel_map_store;
static struct vm_map_entry      kernel_image_mapent_store;
static struct vm_map_entry      kernel_kmem_mapent_store;

size_t nkmempages = 0;
vaddr_t kmembase;
vsize_t kmemsize;

static struct vmem kmem_arena_store;
vmem_t *kmem_arena = NULL;
static struct vmem kmem_va_arena_store;
vmem_t *kmem_va_arena;

/*
 * kmeminit_nkmempages: calculate the size of kmem_arena.
 */
void
kmeminit_nkmempages(void)
{
        size_t npages;

        if (nkmempages != 0) {
                /*
                 * It's already been set (by us being here before)
                 * bail out now;
                 */
                return;
        }

#if defined(NKMEMPAGES_MAX_UNLIMITED) && !defined(KMSAN)
        /*
         * The extra 1/9 here is to account for uvm_km_va_starved_p()
         * wanting to keep 10% of kmem virtual space free.
         * The intent is that on "unlimited" platforms we should be able
         * to allocate all of physical memory as kmem without behaving
         * as though we running short of kmem virtual space.
         */
        npages = (physmem * 10) / 9;
#else

#if defined(KMSAN)
        npages = (physmem / 4);
#elif defined(PMAP_MAP_POOLPAGE)
        npages = (physmem / 4);
#else
        npages = (physmem / 3) * 2;
#endif /* defined(PMAP_MAP_POOLPAGE) */

#if !defined(NKMEMPAGES_MAX_UNLIMITED)
        if (npages > NKMEMPAGES_MAX)
                npages = NKMEMPAGES_MAX;
#endif

#endif

        if (npages < NKMEMPAGES_MIN)
                npages = NKMEMPAGES_MIN;

        nkmempages = npages;
}

/*
 * uvm_km_bootstrap: init kernel maps and objects to reflect reality (i.e.
 * KVM already allocated for text, data, bss, and static data structures).
 *
 * => KVM is defined by VM_MIN_KERNEL_ADDRESS/VM_MAX_KERNEL_ADDRESS.
 *    we assume that [vmin -> start] has already been allocated and that
 *    "end" is the end.
 */

void
uvm_km_bootstrap(vaddr_t start, vaddr_t end)
{
        bool kmem_arena_small;
        vaddr_t base = VM_MIN_KERNEL_ADDRESS;
        struct uvm_map_args args;
        int error;

        UVMHIST_FUNC(__func__);
        UVMHIST_CALLARGS(maphist, "start=%#jx end=%#jx", start, end, 0,0);

        kmeminit_nkmempages();
        kmemsize = (vsize_t)nkmempages * PAGE_SIZE;
        kmem_arena_small = kmemsize < 64 * 1024 * 1024;

        UVMHIST_LOG(maphist, "kmemsize=%#jx", kmemsize, 0,0,0);

        /*
         * next, init kernel memory objects.
         */

        /* kernel_object: for pageable anonymous kernel memory */
        uvm_kernel_object = uao_create(VM_MAX_KERNEL_ADDRESS -
                                VM_MIN_KERNEL_ADDRESS, UAO_FLAG_KERNOBJ);

        /*
         * init the map and reserve any space that might already
         * have been allocated kernel space before installing.
         */

        uvm_map_setup(&kernel_map_store, base, end, VM_MAP_PAGEABLE);
        kernel_map_store.pmap = pmap_kernel();
        if (start != base) {
                error = uvm_map_prepare(&kernel_map_store,
                    base, start - base,
                    NULL, UVM_UNKNOWN_OFFSET, 0,
                    UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
                                UVM_ADV_RANDOM, UVM_FLAG_FIXED), &args);
                if (!error) {
                        kernel_image_mapent_store.flags =
                            UVM_MAP_KERNEL | UVM_MAP_STATIC | UVM_MAP_NOMERGE;
                        error = uvm_map_enter(&kernel_map_store, &args,
                            &kernel_image_mapent_store);
                }

                if (error)
                        panic(
                            "uvm_km_bootstrap: could not reserve space for kernel");

                kmembase = args.uma_start + args.uma_size;
        } else {
                kmembase = base;
        }

        error = uvm_map_prepare(&kernel_map_store,
            kmembase, kmemsize,
            NULL, UVM_UNKNOWN_OFFSET, 0,
            UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
                        UVM_ADV_RANDOM, UVM_FLAG_FIXED), &args);
        if (!error) {
                kernel_kmem_mapent_store.flags =
                    UVM_MAP_KERNEL | UVM_MAP_STATIC | UVM_MAP_NOMERGE;
                error = uvm_map_enter(&kernel_map_store, &args,
                    &kernel_kmem_mapent_store);
        }

        if (error)
                panic("uvm_km_bootstrap: could not reserve kernel kmem");

        /*
         * install!
         */

        kernel_map = &kernel_map_store;

        pool_subsystem_init();

        kmem_arena = vmem_init(&kmem_arena_store, "kmem",
            kmembase, kmemsize, PAGE_SIZE, NULL, NULL, NULL,
            0, VM_NOSLEEP | VM_BOOTSTRAP, IPL_VM);
#ifdef PMAP_GROWKERNEL
        /*
         * kmem_arena VA allocations happen independently of uvm_map.
         * grow kernel to accommodate the kmem_arena.
         */
        if (uvm_maxkaddr < kmembase + kmemsize) {
                uvm_maxkaddr = pmap_growkernel(kmembase + kmemsize);
                KASSERTMSG(uvm_maxkaddr >= kmembase + kmemsize,
                    "%#"PRIxVADDR" %#"PRIxVADDR" %#"PRIxVSIZE,
                    uvm_maxkaddr, kmembase, kmemsize);
        }
#endif

        vmem_subsystem_init(kmem_arena);

        UVMHIST_LOG(maphist, "kmem vmem created (base=%#jx, size=%#jx",
            kmembase, kmemsize, 0,0);

        kmem_va_arena = vmem_init(&kmem_va_arena_store, "kva",
            0, 0, PAGE_SIZE, vmem_alloc, vmem_free, kmem_arena,
            (kmem_arena_small ? 4 : VMEM_QCACHE_IDX_MAX) * PAGE_SIZE,
            VM_NOSLEEP, IPL_VM);

        UVMHIST_LOG(maphist, "<- done", 0,0,0,0);
}

/*
 * uvm_km_init: init the kernel maps virtual memory caches
 * and start the pool/kmem allocator.
 */
void
uvm_km_init(void)
{
        kmem_init();
}

/*
 * uvm_km_suballoc: allocate a submap in the kernel map.   once a submap
 * is allocated all references to that area of VM must go through it.  this
 * allows the locking of VAs in kernel_map to be broken up into regions.
 *
 * => if `fixed' is true, *vmin specifies where the region described
 *   pager_map => used to map "buf" structures into kernel space
 *      by the submap must start
 * => if submap is non NULL we use that as the submap, otherwise we
 *      alloc a new map
 */

struct vm_map *
uvm_km_suballoc(struct vm_map *map, vaddr_t *vmin /* IN/OUT */,
    vaddr_t *vmax /* OUT */, vsize_t size, int flags, bool fixed,
    struct vm_map *submap)
{
        int mapflags = UVM_FLAG_NOMERGE | (fixed ? UVM_FLAG_FIXED : 0);
        UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);

        KASSERT(vm_map_pmap(map) == pmap_kernel());

        size = round_page(size);        /* round up to pagesize */

        /*
         * first allocate a blank spot in the parent map
         */

        if (uvm_map(map, vmin, size, NULL, UVM_UNKNOWN_OFFSET, 0,
            UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_NONE,
            UVM_ADV_RANDOM, mapflags)) != 0) {
                panic("%s: unable to allocate space in parent map", __func__);
        }

        /*
         * set VM bounds (vmin is filled in by uvm_map)
         */

        *vmax = *vmin + size;

        /*
         * add references to pmap and create or init the submap
         */

        pmap_reference(vm_map_pmap(map));
        if (submap == NULL) {
                submap = kmem_alloc(sizeof(*submap), KM_SLEEP);
        }
        uvm_map_setup(submap, *vmin, *vmax, flags);
        submap->pmap = vm_map_pmap(map);

        /*
         * now let uvm_map_submap plug in it...
         */

        if (uvm_map_submap(map, *vmin, *vmax, submap) != 0)
                panic("uvm_km_suballoc: submap allocation failed");

        return(submap);
}

/*
 * uvm_km_pgremove: remove pages from a kernel uvm_object and KVA.
 */

void
uvm_km_pgremove(vaddr_t startva, vaddr_t endva)
{
        struct uvm_object * const uobj = uvm_kernel_object;
        const voff_t start = startva - vm_map_min(kernel_map);
        const voff_t end = endva - vm_map_min(kernel_map);
        struct vm_page *pg;
        voff_t curoff, nextoff;
        int swpgonlydelta = 0;
        UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);

        KASSERT(VM_MIN_KERNEL_ADDRESS <= startva);
        KASSERT(startva < endva);
        KASSERT(endva <= VM_MAX_KERNEL_ADDRESS);

        rw_enter(uobj->vmobjlock, RW_WRITER);
        pmap_remove(pmap_kernel(), startva, endva);
        pmap_update(pmap_kernel());
        for (curoff = start; curoff < end; curoff = nextoff) {
                nextoff = curoff + PAGE_SIZE;
                pg = uvm_pagelookup(uobj, curoff);
                if (pg != NULL && pg->flags & PG_BUSY) {
                        uvm_pagewait(pg, uobj->vmobjlock, "km_pgrm");
                        rw_enter(uobj->vmobjlock, RW_WRITER);
                        nextoff = curoff;
                        continue;
                }

                /*
                 * free the swap slot, then the page.
                 */

                if (pg == NULL &&
                    uao_find_swslot(uobj, curoff >> PAGE_SHIFT) > 0) {
                        swpgonlydelta++;
                }
                uao_dropswap(uobj, curoff >> PAGE_SHIFT);
                if (pg != NULL) {
                        uvm_pagefree(pg);
                }
        }
        rw_exit(uobj->vmobjlock);

        if (swpgonlydelta > 0) {
                KASSERT(uvmexp.swpgonly >= swpgonlydelta);
                atomic_add_int(&uvmexp.swpgonly, -swpgonlydelta);
        }
}


/*
 * uvm_km_pgremove_intrsafe: like uvm_km_pgremove(), but for non object backed
 *    regions.
 *
 * => when you unmap a part of anonymous kernel memory you want to toss
 *    the pages right away.    (this is called from uvm_unmap_...).
 * => none of the pages will ever be busy, and none of them will ever
 *    be on the active or inactive queues (because they have no object).
 */

void
uvm_km_pgremove_intrsafe(struct vm_map *map, vaddr_t start, vaddr_t end)
{
#define __PGRM_BATCH 16
        struct vm_page *pg;
        paddr_t pa[__PGRM_BATCH];
        int npgrm, i;
        vaddr_t va, batch_vastart;

        UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);

        KASSERT(VM_MAP_IS_KERNEL(map));
        KASSERTMSG(vm_map_min(map) <= start,
            "vm_map_min(map) [%#"PRIxVADDR"] <= start [%#"PRIxVADDR"]"
            " (size=%#"PRIxVSIZE")",
            vm_map_min(map), start, end - start);
        KASSERT(start < end);
        KASSERT(end <= vm_map_max(map));

        for (va = start; va < end;) {
                batch_vastart = va;
                /* create a batch of at most __PGRM_BATCH pages to free */
                for (i = 0;
                     i < __PGRM_BATCH && va < end;
                     va += PAGE_SIZE) {
                        if (!pmap_extract(pmap_kernel(), va, &pa[i])) {
                                continue;
                        }
                        i++;
                }
                npgrm = i;
                /* now remove the mappings */
                pmap_kremove(batch_vastart, va - batch_vastart);
                pmap_update(pmap_kernel());
                /* and free the pages */
                for (i = 0; i < npgrm; i++) {
                        pg = PHYS_TO_VM_PAGE(pa[i]);
                        KASSERT(pg);
                        KASSERT(pg->uobject == NULL);
                        KASSERT(pg->uanon == NULL);
                        KASSERT((pg->flags & PG_BUSY) == 0);
                        uvm_pagefree(pg);
                }
        }
#undef __PGRM_BATCH
}

#if defined(DEBUG)
void
uvm_km_check_empty(struct vm_map *map, vaddr_t start, vaddr_t end)
{
        vaddr_t va;
        UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);

        KDASSERT(VM_MAP_IS_KERNEL(map));
        KDASSERT(vm_map_min(map) <= start);
        KDASSERT(start < end);
        KDASSERT(end <= vm_map_max(map));

        for (va = start; va < end; va += PAGE_SIZE) {
                paddr_t pa;

                if (pmap_extract(pmap_kernel(), va, &pa)) {
                        panic("uvm_km_check_empty: va %p has pa %#llx",
                            (void *)va, (long long)pa);
                }
                /*
                 * kernel_object should not have pages for the corresponding
                 * region.  check it.
                 *
                 * why trylock?  because:
                 * - caller might not want to block.
                 * - we can recurse when allocating radix_node for
                 *   kernel_object.
                 */
                if (rw_tryenter(uvm_kernel_object->vmobjlock, RW_READER)) {
                        struct vm_page *pg;

                        pg = uvm_pagelookup(uvm_kernel_object,
                            va - vm_map_min(kernel_map));
                        rw_exit(uvm_kernel_object->vmobjlock);
                        if (pg) {
                                panic("uvm_km_check_empty: "
                                    "has page hashed at %p",
                                    (const void *)va);
                        }
                }
        }
}
#endif /* defined(DEBUG) */

/*
 * uvm_km_alloc: allocate an area of kernel memory.
 *
 * => NOTE: we can return 0 even if we can wait if there is not enough
 *      free VM space in the map... caller should be prepared to handle
 *      this case.
 * => we return KVA of memory allocated
 */

vaddr_t
uvm_km_alloc(struct vm_map *map, vsize_t size, vsize_t align, uvm_flag_t flags)
{
        vaddr_t kva, loopva;
        vaddr_t offset;
        vsize_t loopsize;
        struct vm_page *pg;
        struct uvm_object *obj;
        int pgaflags;
        vm_prot_t prot, vaprot;
        UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);

        KASSERT(vm_map_pmap(map) == pmap_kernel());
        KASSERT((flags & UVM_KMF_TYPEMASK) == UVM_KMF_WIRED ||
                (flags & UVM_KMF_TYPEMASK) == UVM_KMF_PAGEABLE ||
                (flags & UVM_KMF_TYPEMASK) == UVM_KMF_VAONLY);
        KASSERT((flags & UVM_KMF_VAONLY) != 0 || (flags & UVM_KMF_COLORMATCH) == 0);
        KASSERT((flags & UVM_KMF_COLORMATCH) == 0 || (flags & UVM_KMF_VAONLY) != 0);

        /*
         * setup for call
         */

        kva = vm_map_min(map);  /* hint */
        size = round_page(size);
        obj = (flags & UVM_KMF_PAGEABLE) ? uvm_kernel_object : NULL;
        UVMHIST_LOG(maphist,"  (map=%#jx, obj=%#jx, size=%#jx, flags=%#jx)",
            (uintptr_t)map, (uintptr_t)obj, size, flags);

        /*
         * allocate some virtual space
         */

        vaprot = (flags & UVM_KMF_EXEC) ? UVM_PROT_ALL : UVM_PROT_RW;
        if (__predict_false(uvm_map(map, &kva, size, obj, UVM_UNKNOWN_OFFSET,
            align, UVM_MAPFLAG(vaprot, UVM_PROT_ALL, UVM_INH_NONE,
            UVM_ADV_RANDOM,
            (flags & (UVM_KMF_TRYLOCK | UVM_KMF_NOWAIT | UVM_KMF_WAITVA
             | UVM_KMF_COLORMATCH)))) != 0)) {
                UVMHIST_LOG(maphist, "<- done (no VM)",0,0,0,0);
                return(0);
        }

        /*
         * if all we wanted was VA, return now
         */

        if (flags & (UVM_KMF_VAONLY | UVM_KMF_PAGEABLE)) {
                UVMHIST_LOG(maphist,"<- done valloc (kva=%#jx)", kva,0,0,0);
                return(kva);
        }

        /*
         * recover object offset from virtual address
         */

        offset = kva - vm_map_min(kernel_map);
        UVMHIST_LOG(maphist, "  kva=%#jx, offset=%#jx", kva, offset,0,0);

        /*
         * now allocate and map in the memory... note that we are the only ones
         * whom should ever get a handle on this area of VM.
         */

        loopva = kva;
        loopsize = size;

        pgaflags = UVM_FLAG_COLORMATCH;
        if (flags & UVM_KMF_NOWAIT)
                pgaflags |= UVM_PGA_USERESERVE;
        if (flags & UVM_KMF_ZERO)
                pgaflags |= UVM_PGA_ZERO;
        prot = VM_PROT_READ | VM_PROT_WRITE;
        if (flags & UVM_KMF_EXEC)
                prot |= VM_PROT_EXECUTE;
        while (loopsize) {
                KASSERTMSG(!pmap_extract(pmap_kernel(), loopva, NULL),
                    "loopva=%#"PRIxVADDR, loopva);

                pg = uvm_pagealloc_strat(NULL, offset, NULL, pgaflags,
#ifdef UVM_KM_VMFREELIST
                   UVM_PGA_STRAT_ONLY, UVM_KM_VMFREELIST
#else
                   UVM_PGA_STRAT_NORMAL, 0
#endif
                   );

                /*
                 * out of memory?
                 */

                if (__predict_false(pg == NULL)) {
                        if ((flags & UVM_KMF_NOWAIT) ||
                            ((flags & UVM_KMF_CANFAIL) && !uvm_reclaimable())) {
                                /* free everything! */
                                uvm_km_free(map, kva, size,
                                    flags & UVM_KMF_TYPEMASK);
                                return (0);
                        } else {
                                uvm_wait("km_getwait2");        /* sleep here */
                                continue;
                        }
                }

                pg->flags &= ~PG_BUSY;  /* new page */
                UVM_PAGE_OWN(pg, NULL);

                /*
                 * map it in
                 */

                pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg),
                    prot, PMAP_KMPAGE);
                loopva += PAGE_SIZE;
                offset += PAGE_SIZE;
                loopsize -= PAGE_SIZE;
        }

        pmap_update(pmap_kernel());

        if ((flags & UVM_KMF_ZERO) == 0) {
                kmsan_orig((void *)kva, size, KMSAN_TYPE_UVM, __RET_ADDR);
                kmsan_mark((void *)kva, size, KMSAN_STATE_UNINIT);
        }

        UVMHIST_LOG(maphist,"<- done (kva=%#jx)", kva,0,0,0);
        return(kva);
}

/*
 * uvm_km_protect: change the protection of an allocated area
 */

int
uvm_km_protect(struct vm_map *map, vaddr_t addr, vsize_t size, vm_prot_t prot)
{
        return uvm_map_protect(map, addr, addr + round_page(size), prot, false);
}

/*
 * uvm_km_free: free an area of kernel memory
 */

void
uvm_km_free(struct vm_map *map, vaddr_t addr, vsize_t size, uvm_flag_t flags)
{
        UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);

        KASSERT((flags & UVM_KMF_TYPEMASK) == UVM_KMF_WIRED ||
                (flags & UVM_KMF_TYPEMASK) == UVM_KMF_PAGEABLE ||
                (flags & UVM_KMF_TYPEMASK) == UVM_KMF_VAONLY);
        KASSERT((addr & PAGE_MASK) == 0);
        KASSERT(vm_map_pmap(map) == pmap_kernel());

        size = round_page(size);

        if (flags & UVM_KMF_PAGEABLE) {
                uvm_km_pgremove(addr, addr + size);
        } else if (flags & UVM_KMF_WIRED) {
                /*
                 * Note: uvm_km_pgremove_intrsafe() extracts mapping, thus
                 * remove it after.  See comment below about KVA visibility.
                 */
                uvm_km_pgremove_intrsafe(map, addr, addr + size);
        }

        /*
         * Note: pmap_update() for the mappings was done inside
         * uvm_km_pgremove*() above (before any page frees).
         * VAONLY below tells uvm_unmap_remove() to skip pmap work.
         */

        uvm_unmap1(map, addr, addr + size, UVM_FLAG_VAONLY);
}

/* Sanity; must specify both or none. */
#if (defined(PMAP_MAP_POOLPAGE) || defined(PMAP_UNMAP_POOLPAGE)) && \
    (!defined(PMAP_MAP_POOLPAGE) || !defined(PMAP_UNMAP_POOLPAGE))
#error Must specify MAP and UNMAP together.
#endif

#if defined(PMAP_ALLOC_POOLPAGE) && \
    !defined(PMAP_MAP_POOLPAGE) && !defined(PMAP_UNMAP_POOLPAGE)
#error Must specify ALLOC with MAP and UNMAP
#endif

int
uvm_km_kmem_alloc(vmem_t *vm, vmem_size_t size, vm_flag_t flags,
    vmem_addr_t *addr)
{
        struct vm_page *pg;
        vmem_addr_t va;
        int rc;
        vaddr_t loopva;
        vsize_t loopsize;

        size = round_page(size);

#if defined(PMAP_MAP_POOLPAGE)
        if (size == PAGE_SIZE) {
again:
#ifdef PMAP_ALLOC_POOLPAGE
                pg = PMAP_ALLOC_POOLPAGE((flags & VM_SLEEP) ?
                   0 : UVM_PGA_USERESERVE);
#else
                pg = uvm_pagealloc(NULL, 0, NULL,
                   (flags & VM_SLEEP) ? 0 : UVM_PGA_USERESERVE);
#endif /* PMAP_ALLOC_POOLPAGE */
                if (__predict_false(pg == NULL)) {
                        if (flags & VM_SLEEP) {
                                uvm_wait("plpg");
                                goto again;
                        }
                        return ENOMEM;
                }
                va = PMAP_MAP_POOLPAGE(VM_PAGE_TO_PHYS(pg));
                KASSERT(va != 0);
                *addr = va;
                return 0;
        }
#endif /* PMAP_MAP_POOLPAGE */

        rc = vmem_alloc(vm, size, flags, &va);
        if (rc != 0)
                return rc;

#ifdef PMAP_GROWKERNEL
        /*
         * These VA allocations happen independently of uvm_map
         * so this allocation must not extend beyond the current limit.
         */
        KASSERTMSG(uvm_maxkaddr >= va + size,
            "%#"PRIxVADDR" %#"PRIxPTR" %#zx",
            uvm_maxkaddr, va, size);
#endif

        loopva = va;
        loopsize = size;

        while (loopsize) {
                paddr_t pa __diagused;
                KASSERTMSG(!pmap_extract(pmap_kernel(), loopva, &pa),
                    "loopva=%#"PRIxVADDR" loopsize=%#"PRIxVSIZE
                    " pa=%#"PRIxPADDR" vmem=%p",
                    loopva, loopsize, pa, vm);

                pg = uvm_pagealloc(NULL, loopva, NULL,
                    UVM_FLAG_COLORMATCH
                    | ((flags & VM_SLEEP) ? 0 : UVM_PGA_USERESERVE));
                if (__predict_false(pg == NULL)) {
                        if (flags & VM_SLEEP) {
                                uvm_wait("plpg");
                                continue;
                        } else {
                                uvm_km_pgremove_intrsafe(kernel_map, va,
                                    va + size);
                                vmem_free(vm, va, size);
                                return ENOMEM;
                        }
                }

                pg->flags &= ~PG_BUSY;  /* new page */
                UVM_PAGE_OWN(pg, NULL);
                pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg),
                    VM_PROT_READ|VM_PROT_WRITE, PMAP_KMPAGE);

                loopva += PAGE_SIZE;
                loopsize -= PAGE_SIZE;
        }
        pmap_update(pmap_kernel());

        *addr = va;

        return 0;
}

void
uvm_km_kmem_free(vmem_t *vm, vmem_addr_t addr, size_t size)
{

        size = round_page(size);
#if defined(PMAP_UNMAP_POOLPAGE)
        if (size == PAGE_SIZE) {
                paddr_t pa;

                pa = PMAP_UNMAP_POOLPAGE(addr);
                uvm_pagefree(PHYS_TO_VM_PAGE(pa));
                return;
        }
#endif /* PMAP_UNMAP_POOLPAGE */
        uvm_km_pgremove_intrsafe(kernel_map, addr, addr + size);
        pmap_update(pmap_kernel());

        vmem_free(vm, addr, size);
}

bool
uvm_km_va_starved_p(void)
{
        vmem_size_t total;
        vmem_size_t free;

        if (kmem_arena == NULL)
                return false;

        total = vmem_size(kmem_arena, VMEM_ALLOC|VMEM_FREE);
        free = vmem_size(kmem_arena, VMEM_FREE);

        return (free < (total / 10));
}