Function pmap_enter_quick_locked

freebsd/amd64/amd64/pmap.c:7259–7350

}

static vm_page_t
pmap_enter_quick_locked(pmap_t pmap, vm_offset_t va, vm_page_t m,
    vm_prot_t prot, vm_page_t mpte, struct rwlock **lockp)
{
	pt_entry_t newpte, *pte, PG_V;

	KASSERT(va < kmi.clean_sva || va >= kmi.clean_eva ||
	    (m->oflags & VPO_UNMANAGED) != 0,
	    ("pmap_enter_quick_locked: managed mapping within the clean submap"));
	PG_V = pmap_valid_bit(pmap);
	PMAP_LOCK_ASSERT(pmap, MA_OWNED);

	/*
	 * In the case that a page table page is not
	 * resident, we are creating it here.
	 */
	if (va < VM_MAXUSER_ADDRESS) {
		vm_pindex_t ptepindex;
		pd_entry_t *ptepa;

		/*
		 * Calculate pagetable page index
		 */
		ptepindex = pmap_pde_pindex(va);
		if (mpte && (mpte->pindex == ptepindex)) {
			mpte->ref_count++;
		} else {
			/*
			 * Get the page directory entry
			 */
			ptepa = pmap_pde(pmap, va);

			/*
			 * If the page table page is mapped, we just increment
			 * the hold count, and activate it.  Otherwise, we
			 * attempt to allocate a page table page.  If this
			 * attempt fails, we don't retry.  Instead, we give up.
			 */
			if (ptepa && (*ptepa & PG_V) != 0) {
				if (*ptepa & PG_PS)
					return (NULL);
				mpte = PHYS_TO_VM_PAGE(*ptepa & PG_FRAME);
				mpte->ref_count++;
			} else {
				/*
				 * Pass NULL instead of the PV list lock
				 * pointer, because we don't intend to sleep.
				 */
				mpte = pmap_allocpte_alloc(pmap, ptepindex,
				    NULL, va);
				if (mpte == NULL)
					return (mpte);
			}
		}
		pte = (pt_entry_t *)PHYS_TO_DMAP(VM_PAGE_TO_PHYS(mpte));
		pte = &pte[pmap_pte_index(va)];
	} else {
		mpte = NULL;