Function _fetch_page_for_varea

components/mm/mm_anon.c:309–361

get the backup page in kernel for the address in user space */

/* get the backup page in kernel for the address in user space */
static void _fetch_page_for_varea(struct rt_varea *varea, struct rt_aspace_fault_msg *msg, rt_bool_t need_map)
{
    void *paddr;
    char *frame_ka;
    rt_aspace_t curr_aspace = varea->aspace;
    rt_aspace_t backup = _anon_obj_get_backup(varea->mem_obj);

    RDWR_LOCK(curr_aspace);

    /**
     * if the page is already mapped(this may caused by data race while other
     * thread success to take the lock and mapped the page before this), return okay
     */
    paddr = rt_hw_mmu_v2p(curr_aspace, msg->fault_vaddr);
    if (paddr == ARCH_MAP_FAILED)
    {
        if (backup == curr_aspace)
        {
            rt_mm_dummy_mapper.on_page_fault(varea, msg);
            if (msg->response.status != MM_FAULT_STATUS_UNRECOVERABLE)
            {
                /* if backup == curr_aspace, a page fetch always binding with a pte filling */
                _map_page_in_varea(backup, varea, msg, msg->fault_vaddr);
                if (msg->response.status != MM_FAULT_STATUS_UNRECOVERABLE)
                {
                    rt_pages_free(msg->response.vaddr, 0);
                }
            }
        }
        else
        {
            frame_ka = _get_page_from_backup(backup, msg->off);
            if (frame_ka)
            {
                msg->response.vaddr = frame_ka;
                msg->response.size = ARCH_PAGE_SIZE;
                if (!need_map)
                {
                    msg->response.status = MM_FAULT_STATUS_OK;
                }
                else
                {
                    _map_page_in_varea(curr_aspace, varea, msg, msg->fault_vaddr);
                }
            }
        }
    }
    else
    {
        msg->response.status = MM_FAULT_STATUS_OK_MAPPED;
    }
    RDWR_UNLOCK(curr_aspace);
}

static void _anon_page_fault(struct rt_varea *varea, struct rt_aspace_fault_msg *msg)
{