source: mainline/generic/src/ddi/ddi.c@ 9a8d91b

/*
 * 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.
 */

#include <ddi/ddi.h>
#include <ddi/ddi_arg.h>
#include <proc/task.h>
#include <security/cap.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <mm/as.h>
#include <synch/spinlock.h>
#include <arch.h>
#include <align.h>
#include <errno.h>

/** Map piece of physical memory into virtual address space of specified task.
 *
 * @param id Task ID of the destination task.
 * @param pf Physical frame address of the starting frame.
 * @param vp Virtual page address of the starting page.
 * @param pages Number of pages to map.
 * @param writable If true, the mapping will be created writable.
 *
 * @return 0 on success, EPERM if the caller lacks capabilities to use this syscall,
 *         ENOENT if there is no task matching the specified ID and ENOMEM if
 *         there was a problem in creating address space area.
 */
static int ddi_map_physmem(task_id_t id, __address pf, __address vp, count_t pages, bool writable)
{
        ipl_t ipl;
        cap_t caps;
        task_t *t;
        int flags;
        count_t i;
        
        /*
         * Make sure the caller is authorised to make this syscall.
         */
        caps = cap_get(TASK);
        if (!(caps & CAP_MEM_MANAGER))
                return EPERM;
        
        ipl = interrupts_disable();
        spinlock_lock(&tasks_lock);
        
        t = task_find_by_id(id);
        
        if (!t) {
                /*
                 * There is no task with the specified ID.
                 */
                spinlock_unlock(&tasks_lock);
                interrupts_restore(ipl);
                return ENOENT;
        }

        /*
         * TODO: We are currently lacking support for task destroying.
         * Once it is added to the kernel, we must take care to
         * synchronize in a way that prevents race conditions here.
         */
        
        /* Lock the task and release the lock protecting tasks_btree. */
        spinlock_lock(&t->lock);
        spinlock_unlock(&tasks_lock);
        
        flags = AS_AREA_DEVICE | AS_AREA_READ;
        if (writable)
                flags |= AS_AREA_WRITE;
        if (!as_area_create(t->as, flags, pages * PAGE_SIZE, vp)) {
                /*
                 * The address space area could not have been created.
                 * We report it using ENOMEM.
                 */
                spinlock_unlock(&t->lock);
                interrupts_restore(ipl);
                return ENOMEM;
        }
        
        /* Initialize page tables. */
        for (i = 0; i < pages; i++)
                as_set_mapping(t->as, vp + i * PAGE_SIZE, pf + i * FRAME_SIZE);

        spinlock_unlock(&t->lock);
        interrupts_restore(ipl);
        return 0;
}

/** Wrapper for SYS_MAP_PHYSMEM syscall.
 *
 * @param User space address of DDI argument structure.
 *
 * @return 0 on success, otherwise it returns error code found in errno.h
 */ 
__native sys_map_physmem(ddi_arg_t *uspace_ddi_arg)
{
        ddi_arg_t arg;
        
        copy_from_uspace(&arg, uspace_ddi_arg, sizeof(ddi_arg_t));
        return (__native) ddi_map_physmem((task_id_t) arg.task_id, ALIGN_DOWN((__address) arg.phys_base, FRAME_SIZE),
                                          ALIGN_DOWN((__address) arg.virt_base, PAGE_SIZE), (count_t) arg.pages,
                                          (bool) arg.writable);
}