dhcpcd: update README.DRAGONFLY

[dragonfly.git] / sys / vm / vm_kern.c

/*
 * (MPSAFE)
 *
 * 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.
 *
 *      from: @(#)vm_kern.c     8.3 (Berkeley) 1/12/94
 *
 *
 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
 * All rights reserved.
 *
 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
 *
 * 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.
 *
 * $FreeBSD: src/sys/vm/vm_kern.c,v 1.61.2.2 2002/03/12 18:25:26 tegge Exp $
 */

/*
 *      Kernel memory management.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>

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

static struct vm_map kernel_map_store;
static struct vm_map clean_map_store;
static struct vm_map buffer_map_store;

struct vm_map *kernel_map = &kernel_map_store;
struct vm_map *clean_map = &clean_map_store;
struct vm_map *buffer_map = &buffer_map_store;

static __inline
int
KMVMCPU(int kmflags)
{
        if ((kmflags & KM_CPU_SPEC) == 0)
                return 0;
        return VM_ALLOC_CPU(KM_GETCPU(kmflags));
}

/*
 * Allocate pageable swap-backed anonymous memory
 */
void *
kmem_alloc_swapbacked(kmem_anon_desc_t *kp, vm_size_t size, vm_subsys_t id)
{
        int error;
        vm_pindex_t npages;

        size = round_page(size);
        npages = size / PAGE_SIZE;

        if (kp->map == NULL)
                kp->map = kernel_map;
        kp->data = vm_map_min(kernel_map);
        kp->size = size;
        kp->object = vm_object_allocate(OBJT_DEFAULT, npages);

        error = vm_map_find(kp->map, kp->object, NULL, 0,
                            &kp->data, size,
                            PAGE_SIZE, TRUE,
                            VM_MAPTYPE_NORMAL, id,
                            VM_PROT_ALL, VM_PROT_ALL, 0);
        if (error) {
                kprintf("kmem_alloc_swapbacked: %zd bytes failed %d\n",
                        size, error);
                kp->data = (vm_offset_t)0;
                kmem_free_swapbacked(kp);
                return NULL;
        }
        return ((void *)(intptr_t)kp->data);
}

void
kmem_free_swapbacked(kmem_anon_desc_t *kp)
{
        if (kp->data) {
                /*
                 * The object will be deallocated by kmem_free().
                 */
                kmem_free(kp->map, kp->data, kp->size);
                kp->data = (vm_offset_t)0;
        } else {
                /*
                 * Failure during allocation, object must be deallocated
                 * manually.
                 */
                vm_object_deallocate(kp->object);
        }
        kp->object = NULL;
}

/*
 * Allocate pageable memory to the kernel's address map.  "map" must
 * be kernel_map or a submap of kernel_map.  Caller must adjust map or
 * enter VM pages itself.
 *
 * No requirements.
 */
vm_offset_t
kmem_alloc_pageable(vm_map_t map, vm_size_t size, vm_subsys_t id)
{
        vm_offset_t addr;
        int result;

        size = round_page(size);
        addr = vm_map_min(map);
        result = vm_map_find(map, NULL, NULL,
                             (vm_offset_t) 0, &addr, size,
                             PAGE_SIZE, TRUE,
                             VM_MAPTYPE_NORMAL, id,
                             VM_PROT_ALL, VM_PROT_ALL, 0);
        if (result != KERN_SUCCESS)
                return (0);
        return (addr);
}

/*
 * Same as kmem_alloc_pageable, except that it create a nofault entry.
 *
 * No requirements.
 */
vm_offset_t
kmem_alloc_nofault(vm_map_t map, vm_size_t size, vm_subsys_t id,
                   vm_size_t align)
{
        vm_offset_t addr;
        int result;

        size = round_page(size);
        addr = vm_map_min(map);
        result = vm_map_find(map, NULL, NULL,
                             (vm_offset_t) 0, &addr, size,
                             align, TRUE,
                             VM_MAPTYPE_NORMAL, id,
                             VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
        if (result != KERN_SUCCESS)
                return (0);
        return (addr);
}

/*
 * Allocate wired-down memory in the kernel's address map or a submap.
 *
 * No requirements.
 */
vm_offset_t
kmem_alloc3(vm_map_t map, vm_size_t size, vm_subsys_t id, int kmflags)
{
        vm_offset_t addr;
        vm_offset_t gstart;
        vm_offset_t i;
        int count;
        int cow;

        size = round_page(size);

        if (kmflags & KM_KRESERVE)
                count = vm_map_entry_kreserve(MAP_RESERVE_COUNT);
        else
                count = vm_map_entry_reserve(MAP_RESERVE_COUNT);

        if (kmflags & KM_STACK) {
                cow = MAP_IS_KSTACK;
                gstart = PAGE_SIZE;
        } else {
                cow = 0;
                gstart = 0;
        }

        /*
         * Use the kernel object for wired-down kernel pages. Assume that no
         * region of the kernel object is referenced more than once.
         *
         * Locate sufficient space in the map.  This will give us the final
         * virtual address for the new memory, and thus will tell us the
         * offset within the kernel map.
         */
        vm_map_lock(map);
        if (vm_map_findspace(map, vm_map_min(map), size, PAGE_SIZE, 0, &addr)) {
                vm_map_unlock(map);
                if (kmflags & KM_KRESERVE)
                        vm_map_entry_krelease(count);
                else
                        vm_map_entry_release(count);
                return (0);
        }
        vm_object_hold(kernel_object);
        vm_object_reference_locked(kernel_object);
        vm_map_insert(map, &count,
                      kernel_object, NULL,
                      addr, NULL,
                      addr, addr + size,
                      VM_MAPTYPE_NORMAL, id,
                      VM_PROT_ALL, VM_PROT_ALL, cow);
        vm_object_drop(kernel_object);

        vm_map_unlock(map);
        if (kmflags & KM_KRESERVE)
                vm_map_entry_krelease(count);
        else
                vm_map_entry_release(count);

        /*
         * Guarantee that there are pages already in this object before
         * calling vm_map_kernel_wiring().  This is to prevent the following
         * scenario:
         *
         * 1) Threads have swapped out, so that there is a pager for the
         * kernel_object. 2) The kmsg zone is empty, and so we are
         * kmem_allocing a new page for it. 3) vm_map_kernel_wiring() calls
         * vm_fault(); there is no page, but there is a pager, so we call
         * pager_data_request.  But the kmsg zone is empty, so we must
         * kmem_alloc. 4) goto 1 5) Even if the kmsg zone is not empty: when
         * we get the data back from the pager, it will be (very stale)
         * non-zero data.  kmem_alloc is defined to return zero-filled memory.
         *
         * We're intentionally not activating the pages we allocate to prevent a
         * race with page-out.  vm_map_kernel_wiring() will wire the pages.
         */
        vm_object_hold(kernel_object);
        for (i = gstart; i < size; i += PAGE_SIZE) {
                vm_page_t mem;

                mem = vm_page_grab(kernel_object, OFF_TO_IDX(addr + i),
                                   VM_ALLOC_FORCE_ZERO | VM_ALLOC_NORMAL |
                                   VM_ALLOC_RETRY | KMVMCPU(kmflags));
                vm_page_unqueue_nowakeup(mem);
                vm_page_wakeup(mem);
        }
        vm_object_drop(kernel_object);

        /*
         * And finally, mark the data as pageable or non-pageable (unwiring
         * or wiring the pages), according to the passed-in kmflags.
         *
         * NOTE: vm_map_kernel_wiring() handles any kstack guard.
         */
        vm_map_kernel_wiring(map, addr, addr + size, kmflags);

        return (addr);
}

/*
 * Release a region of kernel virtual memory allocated with kmem_alloc,
 * and return the physical pages associated with that region.
 *
 * WARNING!  If the caller entered pages into the region using pmap_kenter()
 * it must remove the pages using pmap_kremove[_quick]() before freeing the
 * underlying kmem, otherwise resident_count will be mistabulated.
 *
 * No requirements.
 */
void
kmem_free(vm_map_t map, vm_offset_t addr, vm_size_t size)
{
        vm_map_remove(map, trunc_page(addr), round_page(addr + size));
}

/*
 * Used to break a system map into smaller maps, usually to reduce
 * contention and to provide large KVA spaces for subsystems like the
 * buffer cache.
 *
 *      parent          Map to take range from
 *      result  
 *      size            Size of range to find
 *      min, max        Returned endpoints of map
 *      pageable        Can the region be paged
 *
 * No requirements.
 */
void
kmem_suballoc(vm_map_t parent, vm_map_t result,
              vm_offset_t *min, vm_offset_t *max, vm_size_t size)
{
        int ret;

        size = round_page(size);

        *min = (vm_offset_t) vm_map_min(parent);
        ret = vm_map_find(parent, NULL, NULL,
                          (vm_offset_t) 0, min, size,
                          PAGE_SIZE, TRUE,
                          VM_MAPTYPE_UNSPECIFIED, VM_SUBSYS_SYSMAP,
                          VM_PROT_ALL, VM_PROT_ALL, 0);
        if (ret != KERN_SUCCESS) {
                kprintf("kmem_suballoc: bad status return of %d.\n", ret);
                panic("kmem_suballoc");
        }
        *max = *min + size;
        pmap_reference(vm_map_pmap(parent));
        vm_map_init(result, *min, *max, vm_map_pmap(parent));
        if ((ret = vm_map_submap(parent, *min, *max, result)) != KERN_SUCCESS)
                panic("kmem_suballoc: unable to change range to submap");
}

/*
 * Allocates pageable memory from a sub-map of the kernel.  If the submap
 * has no room, the caller sleeps waiting for more memory in the submap.
 *
 * No requirements.
 */
vm_offset_t
kmem_alloc_wait(vm_map_t map, vm_size_t size, vm_subsys_t id)
{
        vm_offset_t addr;
        int count;

        size = round_page(size);

        count = vm_map_entry_reserve(MAP_RESERVE_COUNT);

        for (;;) {
                /*
                 * To make this work for more than one map, use the map's lock
                 * to lock out sleepers/wakers.
                 */
                vm_map_lock(map);
                if (vm_map_findspace(map, vm_map_min(map),
                                     size, PAGE_SIZE, 0, &addr) == 0) {
                        break;
                }
                /* no space now; see if we can ever get space */
                if (vm_map_max(map) - vm_map_min(map) < size) {
                        vm_map_entry_release(count);
                        vm_map_unlock(map);
                        return (0);
                }
                vm_map_unlock(map);
                tsleep(map, 0, "kmaw", 0);
        }
        vm_map_insert(map, &count,
                      NULL, NULL,
                      (vm_offset_t)0, NULL,
                      addr, addr + size,
                      VM_MAPTYPE_NORMAL, id,
                      VM_PROT_ALL, VM_PROT_ALL, 0);
        vm_map_unlock(map);
        vm_map_entry_release(count);

        return (addr);
}

/*
 *  Allocates a region from the kernel address map and physical pages
 *  within the specified address range to the kernel object.  Creates a
 *  wired mapping from this region to these pages, and returns the
 *  region's starting virtual address.  The allocated pages are not
 *  necessarily physically contiguous.  If M_ZERO is specified through the
 *  given flags, then the pages are zeroed before they are mapped.
 */
vm_offset_t
kmem_alloc_attr(vm_map_t map, vm_size_t size, vm_subsys_t id,
                int flags, vm_paddr_t low,
                vm_paddr_t high, vm_memattr_t memattr)
{
        vm_offset_t addr, i, offset;
        vm_page_t m;
        int count;

        size = round_page(size);
        count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
        vm_map_lock(map);
        if (vm_map_findspace(map, vm_map_min(map), size, PAGE_SIZE,
                             flags, &addr)) {
                vm_map_unlock(map);
                vm_map_entry_release(count);
                return (0);
        }
        offset = addr - vm_map_min(kernel_map);
        vm_object_hold(kernel_object);
        vm_object_reference_locked(kernel_object);
        vm_map_insert(map, &count,
                      kernel_object, NULL,
                      offset, NULL,
                      addr, addr + size,
                      VM_MAPTYPE_NORMAL, id,
                      VM_PROT_ALL, VM_PROT_ALL, 0);
        vm_map_unlock(map);
        vm_map_entry_release(count);
        vm_object_drop(kernel_object);
        for (i = 0; i < size; i += PAGE_SIZE) {
                m = vm_page_alloc_contig(low, high, PAGE_SIZE, 0,
                                         PAGE_SIZE, memattr);
                if (!m) {
                        return (0);
                }
                vm_object_hold(kernel_object);
                vm_page_insert(m, kernel_object, OFF_TO_IDX(offset + i));
                vm_object_drop(kernel_object);
                if (flags & M_ZERO)
                        pmap_zero_page(VM_PAGE_TO_PHYS(m));
                m->valid = VM_PAGE_BITS_ALL;
        }

        /* wire the pages */
        vm_map_kernel_wiring(map, addr, addr + size, 0);

        return (addr);
}


/*
 * Returns memory to a submap of the kernel, and wakes up any processes
 * waiting for memory in that map.
 *
 * No requirements.
 */
void
kmem_free_wakeup(vm_map_t map, vm_offset_t addr, vm_size_t size)
{
        int count;

        count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
        vm_map_lock(map);
        vm_map_delete(map, trunc_page(addr), round_page(addr + size), &count);
        wakeup(map);
        vm_map_unlock(map);
        vm_map_entry_release(count);
}

/*
 * Create the kernel_ma for (KvaStart,KvaEnd) and insert mappings to
 * cover areas already allocated or reserved thus far.
 *
 * The areas (virtual_start, virtual_end) and (virtual2_start, virtual2_end)
 * are available so the cutouts are the areas around these ranges between
 * KvaStart and KvaEnd.
 *
 * Depend on the zalloc bootstrap cache to get our vm_map_entry_t.
 * Called from the low level boot code only.
 */
void
kmem_init(void)
{
        vm_offset_t addr;
        vm_map_t m;
        int count;

        m = kernel_map;
        vm_map_init(m, KvaStart, KvaEnd, kernel_pmap);
        vm_map_lock(m);
        /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
        m->system_map = 1;
        count = vm_map_entry_reserve(MAP_RESERVE_COUNT);
        addr = KvaStart;
        if (virtual2_start) {
                if (addr < virtual2_start) {
                        vm_map_insert(m, &count,
                                      NULL, NULL,
                                      (vm_offset_t) 0, NULL,
                                      addr, virtual2_start,
                                      VM_MAPTYPE_NORMAL, VM_SUBSYS_RESERVED,
                                      VM_PROT_ALL, VM_PROT_ALL, 0);
                }
                addr = virtual2_end;
        }
        if (addr < virtual_start) {
                vm_map_insert(m, &count,
                              NULL, NULL,
                              (vm_offset_t) 0, NULL,
                              addr, virtual_start,
                              VM_MAPTYPE_NORMAL, VM_SUBSYS_RESERVED,
                              VM_PROT_ALL, VM_PROT_ALL, 0);
        }
        addr = virtual_end;
        if (addr < KvaEnd) {
                vm_map_insert(m, &count,
                              NULL, NULL,
                              (vm_offset_t) 0, NULL,
                              addr, KvaEnd,
                              VM_MAPTYPE_NORMAL, VM_SUBSYS_RESERVED,
                              VM_PROT_ALL, VM_PROT_ALL, 0);
        }
        /* ... and ending with the completion of the above `insert' */
        vm_map_unlock(m);
        vm_map_entry_release(count);
}

/*
 * No requirements.
 */
static int
kvm_size(SYSCTL_HANDLER_ARGS)
{
        unsigned long ksize = KvaSize;

        return sysctl_handle_long(oidp, &ksize, 0, req);
}
SYSCTL_PROC(_vm, OID_AUTO, kvm_size, CTLTYPE_ULONG|CTLFLAG_RD,
    0, 0, kvm_size, "LU", "Size of KVM");
 
/*
 * No requirements.
 */
static int
kvm_free(SYSCTL_HANDLER_ARGS)
{
        unsigned long kfree = virtual_end - kernel_vm_end;

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