static
int
vm_region_expand( struct vm_region *vmr, unsigned npages ) {
unsigned new_pages;
int res;
unsigned i;
unsigned old_pages;
old_pages = vm_page_array_num( vmr->vmr_pages );
new_pages = npages - old_pages;
//trivial case, nothing to do.
if( new_pages == 0 )
return 0;
//see if we can back this loan with storage.
res = swap_reserve( new_pages );
if( res )
return res;
//attempt to rezize the vmr_pages array.
res = vm_page_array_setsize( vmr->vmr_pages, npages );
if( res ) {
swap_unreserve( new_pages );
return res;
}
//initialize each of the newly created vm_pages to NULL.
for( i = old_pages; i < npages; ++i )
vm_page_array_set( vmr->vmr_pages, i, NULL );
return 0;
}
/*
* vm_object_setsize: change the size of a vm_object.
*/
int
vm_object_setsize(struct addrspace *as, struct vm_object *vmo, unsigned npages)
{
int result;
unsigned i;
struct lpage *lp;
KASSERT(vmo != NULL);
KASSERT(vmo->vmo_lpages != NULL);
if (npages < lpage_array_num(vmo->vmo_lpages)) {
for (i=npages; i<lpage_array_num(vmo->vmo_lpages); i++) {
lp = lpage_array_get(vmo->vmo_lpages, i);
if (lp != NULL) {
KASSERT(as != NULL);
/* remove any tlb entry for this mapping */
mmu_unmap(as, vmo->vmo_base+PAGE_SIZE*i);
lpage_destroy(lp);
}
else {
swap_unreserve(1);
}
}
result = lpage_array_setsize(vmo->vmo_lpages, npages);
/* shrinking an array shouldn't fail */
KASSERT(result==0);
}
else if (npages > lpage_array_num(vmo->vmo_lpages)) {
int oldsize = lpage_array_num(vmo->vmo_lpages);
unsigned newpages = npages - oldsize;
result = swap_reserve(newpages);
if (result) {
return result;
}
result = lpage_array_setsize(vmo->vmo_lpages, npages);
if (result) {
swap_unreserve(newpages);
return result;
}
for (i=oldsize; i<npages; i++) {
lpage_array_set(vmo->vmo_lpages, i, NULL);
}
}
return 0;
}
struct vm_region *
vm_region_create( size_t npages ) {
int res;
struct vm_region *vmr;
unsigned i;
int err;
//see if we can reserve npages of swap first.
err = swap_reserve( npages );
if( err )
return NULL;
//attempt to create the vm_region
vmr = kmalloc( sizeof( struct vm_region ) );
if( vmr == NULL )
return NULL;
//create the vm_pages.
vmr->vmr_pages = vm_page_array_create();
if( vmr->vmr_pages == NULL ) {
kfree( vmr );
swap_unreserve( npages );
return NULL;
}
//set the base address to point to an invalid virtual address.
vmr->vmr_base = 0xdeadbeef;
//adjust the array to hold npages.
res = vm_page_array_setsize( vmr->vmr_pages, npages );
if( res ) {
vm_page_array_destroy( vmr->vmr_pages );
kfree( vmr );
swap_unreserve( npages );
return NULL;
}
//initialize all the pages to NULL.
for( i = 0; i < npages; ++i )
vm_page_array_set( vmr->vmr_pages, i, NULL );
return vmr;
}
/*
* vm_object_create: Allocate a new vm_object with nothing in it.
* Returns: new vm_object on success, NULL on error.
*/
struct vm_object *
vm_object_create(size_t npages)
{
struct vm_object *vmo;
unsigned i;
int result;
result = swap_reserve(npages);
if (result != 0) {
return NULL;
}
vmo = kmalloc(sizeof(struct vm_object));
if (vmo == NULL) {
swap_unreserve(npages);
return NULL;
}
vmo->vmo_lpages = lpage_array_create();
if (vmo->vmo_lpages == NULL) {
kfree(vmo);
swap_unreserve(npages);
return NULL;
}
vmo->vmo_base = 0xdeafbeef; /* make sure these */
vmo->vmo_lower_redzone = 0xdeafbeef; /* get filled in later */
/* add the requested number of zerofilled pages */
result = lpage_array_setsize(vmo->vmo_lpages, npages);
if (result) {
lpage_array_destroy(vmo->vmo_lpages);
kfree(vmo);
swap_unreserve(npages);
return NULL;
}
for (i=0; i<npages; i++) {
lpage_array_set(vmo->vmo_lpages, i, NULL);
}
return vmo;
}
static
int
vm_region_shrink( struct vm_region *vmr, unsigned npages ) {
unsigned i;
struct vm_page *vmp;
for( i = npages; i < vm_page_array_num( vmr->vmr_pages ); ++i ) {
vmp = vm_page_array_get( vmr->vmr_pages, i );
if( vmp == NULL ) {
swap_unreserve( 1 );
continue;
}
//unmap tlb entries.
vm_unmap( vmr->vmr_base + PAGE_SIZE * i );
//destroy the page.
vm_page_destroy( vmp );
}
return vm_page_array_setsize( vmr->vmr_pages, npages );
}
