Function vm_thread_stack_create

freebsd/vm/vm_glue.c:290–332

* Create the kernel stack (including pcb for i386) for a new thread. */

 * Create the kernel stack (including pcb for i386) for a new thread.
 */
static vm_offset_t
vm_thread_stack_create(struct domainset *ds, int pages)
{
	vm_page_t ma[KSTACK_MAX_PAGES];
	vm_offset_t ks;
	int i;

	/*
	 * Get a kernel virtual address for this thread's kstack.
	 */
#if defined(__mips__)
	/*
	 * We need to align the kstack's mapped address to fit within
	 * a single TLB entry.
	 */
	if (vmem_xalloc(kernel_arena, (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE,
	    PAGE_SIZE * 2, 0, 0, VMEM_ADDR_MIN, VMEM_ADDR_MAX,
	    M_BESTFIT | M_NOWAIT, &ks)) {
		ks = 0;
	}
#else
	ks = kva_alloc((pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
#endif
	if (ks == 0) {
		printf("%s: kstack allocation failed\n", __func__);
		return (0);
	}

	if (KSTACK_GUARD_PAGES != 0) {
		pmap_qremove(ks, KSTACK_GUARD_PAGES);
		ks += KSTACK_GUARD_PAGES * PAGE_SIZE;
	}

	/*
	 * Allocate physical pages to back the stack.
	 */
	vm_thread_stack_back(ds, ks, ma, pages, VM_ALLOC_NORMAL);
	for (i = 0; i < pages; i++)
		vm_page_valid(ma[i]);
	pmap_qenter(ks, ma, pages);

	return (ks);
}

static void
vm_thread_stack_dispose(vm_offset_t ks, int pages)