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/*-

 * Copyright (c) 2005-2009, Kohsuke Ohtani

 * 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.

 * 3. Neither the name of the author nor the names of any co-contributors

 *    may be used to endorse or promote products derived from this software

 *    without specific prior written permission.

 *

 * 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.

 */

/*

 * page.c - physical page allocator

 */

/*

 * Simple list-based page allocator:

 *

 * When the remaining page is exhausted, what should we do ?

 * If the system can stop with panic() here, the error check of

 * many portions in kernel is not necessary, and kernel code can

 * become more simple. But, in general, even if a page is

 * exhausted, a kernel can not be stopped but it should return an

 * error and continue processing.  If the memory becomes short

 * during boot time, kernel and drivers can use panic() in that

 * case.

 */

#include <kernel.h>

#include <page.h>

#include <sched.h>

#include <hal.h>

/*

 * The page structure is put on the head of the first page of

 * each free block.

 */

struct page {

        struct page        *next;

        struct page        *prev;

        vsize_t                size;                /* number of bytes of this block */

};

static struct page        page_head;        /* first free block */

static psize_t                total_size;        /* size of memory in the system */

static psize_t                used_size;        /* current used size */

static psize_t                bootdisk_size;        /* size of the boot disk */

/*

 * page_alloc - allocate continuous pages of the specified size.

 *

 * This routine returns the physical address of a new free page

 * block, or returns NULL on failure. The requested size is

 * automatically round up to the page boundary.  The allocated

 * memory is _not_ filled with 0.

 */

paddr_t

page_alloc(psize_t psize)

{

        struct page *blk, *tmp;

        vsize_t size;

        ASSERT(psize != 0);

        sched_lock();

        /*

         * Find the free block that has enough size.

         */

        size = round_page(psize);

        blk = &page_head;

        do {

                blk = blk->next;

                if (blk == &page_head) {

                        sched_unlock();

                        DPRINTF(("page_alloc: out of memory\n"));

                        return 0;        /* Not found. */

                }

        } while (blk->size < size);

        /*

         * If found block size is exactly same with requested,

         * just remove it from a free list. Otherwise, the

         * found block is divided into two and first half is

         * used for allocation.

         */

        if (blk->size == size) {

                blk->prev->next = blk->next;

                blk->next->prev = blk->prev;

        } else {

                tmp = (struct page *)((vaddr_t)blk + size);

                tmp->size = blk->size - size;

                tmp->prev = blk->prev;

                tmp->next = blk->next;

                blk->prev->next = tmp;

                blk->next->prev = tmp;

        }

        used_size += (psize_t)size;

        sched_unlock();

        return kvtop(blk);

}

/*

 * Free page block.

 *

 * This allocator does not maintain the size of allocated page

 * block. The caller must provide the size information of the

 * block.

 */

void

page_free(paddr_t paddr, psize_t psize)

{

        struct page *blk, *prev;

        vsize_t size;

        ASSERT(psize != 0);

        sched_lock();

        size = round_page(psize);

        blk = ptokv(paddr);

        /*

         * Find the target position in list.

         */

        for (prev = &page_head; prev->next < blk; prev = prev->next) {

                if (prev->next == &page_head)

                        break;

        }

        /*

         * Insert new block into list.

         */

        blk->size = size;

        blk->prev = prev;

        blk->next = prev->next;

        prev->next->prev = blk;

        prev->next = blk;

        /*

         * If the adjoining block is free, it combines and

         * is made on block.

         */

        if (blk->next != &page_head &&

            ((vaddr_t)blk + blk->size) == (vaddr_t)blk->next) {

                blk->size += blk->next->size;

                blk->next = blk->next->next;

                blk->next->prev = blk;

        }

        if (blk->prev != &page_head &&

            (vaddr_t)blk->prev + blk->prev->size == (vaddr_t)blk) {

                blk->prev->size += blk->size;

                blk->prev->next = blk->next;

                blk->next->prev = blk->prev;

        }

        used_size -= (psize_t)size;

        sched_unlock();

}

/*

 * The function to reserve pages in specific address.

 */

int

page_reserve(paddr_t paddr, psize_t psize)

{

        struct page *blk, *tmp;

        vaddr_t start, end;

        vsize_t size;

        if (psize == 0)

                return 0;

        start = trunc_page((vaddr_t)ptokv(paddr));

        end = round_page((vaddr_t)ptokv(paddr + psize));

        size = end - start;

        /*

         * Find the block which includes specified block.

         */

        blk = page_head.next;

        for (;;) {

                if (blk == &page_head)

                        return ENOMEM;

                if ((vaddr_t)blk <= start

                    && end <= (vaddr_t)blk + blk->size)

                        break;

                blk = blk->next;

        }

        if ((vaddr_t)blk == start && blk->size == size) {

                /*

                 * Unlink the block from free list.

                 */

                blk->prev->next = blk->next;

                blk->next->prev = blk->prev;

        } else {

                /*

                 * Split this block.

                 */

                if ((vaddr_t)blk + blk->size != end) {

                        tmp = (struct page *)end;

                        tmp->size = (vaddr_t)blk + blk->size - end;

                        tmp->next = blk->next;

                        tmp->prev = blk;

                        blk->size -= tmp->size;

                        blk->next->prev = tmp;

                        blk->next = tmp;

                }

                if ((vaddr_t)blk == start) {

                        blk->prev->next = blk->next;

                        blk->next->prev = blk->prev;

                } else

                        blk->size = start - (vaddr_t)blk;

        }

        used_size += (psize_t)size;

        return 0;

}

void

page_info(struct meminfo *info)

{

        info->total = total_size;

        info->free = total_size - used_size;

        info->bootdisk = bootdisk_size;

#ifndef CONFIG_ROMBOOT

        /*

         * The boot disk is placed at RAM.

         */

        info->free -= bootdisk_size;

#endif

}

/*

 * Initialize page allocator.

 * page_init() must be called prior to other memory manager's

 * initializations.

 */

void

page_init(void)

{

        struct physmem *ram;

        struct bootinfo *bi;

        int i;

        machine_bootinfo(&bi);

        total_size = 0;

        bootdisk_size = 0;

        page_head.next = page_head.prev = &page_head;

        /*

         * First, create a free list from the boot information.

         */

        for (i = 0; i < bi->nr_rams; i++) {

                ram = &bi->ram[i];

                if (ram->type == MT_USABLE) {

                        page_free(ram->base, ram->size);

                        total_size += ram->size;

                }

        }

        /*

         * Then, reserve un-usable memory.

         */

        for (i = 0; i < bi->nr_rams; i++) {

                ram = &bi->ram[i];

                switch (ram->type) {

                case MT_BOOTDISK:

                        bootdisk_size += ram->size;

                        /* FALLTHROUGH */

                case MT_MEMHOLE:

                        total_size -= ram->size;

                        /* FALLTHROUGH */

                case MT_RESERVED:

                        if (page_reserve(ram->base, ram->size))

                                panic("page_init");

                        break;

                }

        }

        used_size = 0;

        DPRINTF(("Memory size=%ld\n", total_size));

}