source: mainline/kernel/generic/src/mm/backend_phys.c@ dbb29de

/*
 * Copyright (c) 2006 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - 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.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 */

/** @addtogroup genericmm
 * @{
 */

/**
 * @file
 * @brief       Backend for address space areas backed by continuous physical
 *              memory.
 */

#include <debug.h>
#include <typedefs.h>
#include <mm/as.h>
#include <mm/page.h>
#include <mm/frame.h>
#include <mm/slab.h>
#include <memstr.h>
#include <macros.h>
#include <arch.h>
#include <align.h>

static bool phys_create(as_area_t *);
static void phys_share(as_area_t *);
static void phys_destroy(as_area_t *);

static bool phys_is_resizable(as_area_t *);
static bool phys_is_shareable(as_area_t *);


static int phys_page_fault(as_area_t *, uintptr_t, pf_access_t);

mem_backend_t phys_backend = {
        .create = phys_create,
        .resize = NULL,
        .share = phys_share,
        .destroy = phys_destroy,

        .is_resizable = phys_is_resizable,
        .is_shareable = phys_is_shareable,

        .page_fault = phys_page_fault,
        .frame_free = NULL,
};

bool phys_create(as_area_t *area)
{
        return true;
}

/** Share address space area backed by physical memory.
 *
 * Do actually nothing as sharing of address space areas
 * that are backed up by physical memory is very easy.
 * Note that the function must be defined so that
 * as_area_share() will succeed.
 */
void phys_share(as_area_t *area)
{
        ASSERT(mutex_locked(&area->as->lock));
        ASSERT(mutex_locked(&area->lock));
}


void phys_destroy(as_area_t *area)
{
        mem_backend_data_t *data = &area->backend_data;
        bool last = true;

        if (area->sh_info) {
                mutex_lock(&area->sh_info->lock);
                if (area->sh_info->refcount != 1)
                        last = false;
                mutex_unlock(&area->sh_info->lock);
        }
        
        if (last && data->anonymous)
                frame_free(data->base, data->frames);
}

bool phys_is_resizable(as_area_t *area)
{
        return false;
}

bool phys_is_shareable(as_area_t *area)
{
        return true;
}


/** Service a page fault in the address space area backed by physical memory.
 *
 * The address space area and page tables must be already locked.
 *
 * @param area Pointer to the address space area.
 * @param upage Faulting virtual page.
 * @param access Access mode that caused the fault (i.e. read/write/exec).
 *
 * @return AS_PF_FAULT on failure (i.e. page fault) or AS_PF_OK on success (i.e.
 * serviced).
 */
int phys_page_fault(as_area_t *area, uintptr_t upage, pf_access_t access)
{
        uintptr_t base = area->backend_data.base;

        ASSERT(page_table_locked(AS));
        ASSERT(mutex_locked(&area->lock));
        ASSERT(IS_ALIGNED(upage, PAGE_SIZE));

        if (!as_area_check_access(area, access))
                return AS_PF_FAULT;

        ASSERT(upage - area->base < area->backend_data.frames * FRAME_SIZE);
        page_mapping_insert(AS, upage, base + (upage - area->base),
            as_area_get_flags(area));
        
        if (!used_space_insert(area, upage, 1))
                panic("Cannot insert used space.");

        return AS_PF_OK;
}

/** @}
 */