Function rt_varea_fix_private_locked

components/mm/mm_anon.c:555–629

* replace an existing mapping to a private one, this is identical to: * => aspace_unmap(ex_varea, ) * => aspace_map() */

 * => aspace_map()
 */
int rt_varea_fix_private_locked(rt_varea_t ex_varea, void *pa,
                                struct rt_aspace_fault_msg *msg,
                                rt_bool_t dont_copy)
{
    /**
     * todo: READ -> WRITE lock here
     */
    void *page;
    void *fault_vaddr;
    rt_aspace_t aspace;
    rt_mem_obj_t ex_obj;
    int rc = MM_FAULT_FIXABLE_FALSE;
    ex_obj = ex_varea->mem_obj;

    if (ex_obj)
    {
        fault_vaddr = msg->fault_vaddr;
        aspace = ex_varea->aspace;
        RT_ASSERT(!!aspace);

        /**
         * todo: what if multiple pages are required?
         */
        if (aspace->private_object == ex_obj)
        {
            RT_ASSERT(0 && "recursion");
        }
        else if (ex_obj->page_read)
        {
            page = rt_pages_alloc_tagged(0, RT_PAGE_PICK_AFFID(fault_vaddr), PAGE_ANY_AVAILABLE);
            if (page)
            {
                /** setup message & fetch the data from source object */
                if (!dont_copy)
                {
                    struct rt_aspace_io_msg io_msg;
                    rt_mm_io_msg_init(&io_msg, msg->off, msg->fault_vaddr, page);
                    ex_obj->page_read(ex_varea, &io_msg);
                    /**
                     * Note: if ex_obj have mapped into varea, it's still okay since
                     * we will override it latter
                     */
                    if (io_msg.response.status != MM_FAULT_STATUS_UNRECOVERABLE)
                    {
                        rc = _override_map(ex_varea, aspace, fault_vaddr, msg, page);
                    }
                    else
                    {
                        rt_pages_free(page, 0);
                        LOG_I("%s: page read(va=%p) fault from %s(start=%p,size=%p)", __func__,
                            msg->fault_vaddr, VAREA_NAME(ex_varea), ex_varea->start, ex_varea->size);
                    }
                }
                else
                {
                    rc = _override_map(ex_varea, aspace, fault_vaddr, msg, page);
                }
            }