Function pmap_allocpte_nosleep

freebsd/amd64/amd64/pmap.c:4392–4515

* The ptepindexes, i.e. page indices, of the page table pages encountered * while translating virtual address va are defined as follows: * - for the page table page (last level), * ptepindex = pmap_pde_pindex(va) = va >> PDRSHIFT, * in other words, it is just the index of the PDE that maps the page * table page. * - for the page directory page, * ptepindex = NUPDE (number of u

 * since it is statically allocated by pmap_pinit() and not by pmap_allocpte().
 */
static vm_page_t
pmap_allocpte_nosleep(pmap_t pmap, vm_pindex_t ptepindex, struct rwlock **lockp,
    vm_offset_t va)
{
	vm_pindex_t pml5index, pml4index;
	pml5_entry_t *pml5, *pml5u;
	pml4_entry_t *pml4, *pml4u;
	pdp_entry_t *pdp;
	pd_entry_t *pd;
	vm_page_t m, pdpg;
	pt_entry_t PG_A, PG_M, PG_RW, PG_V;

	PMAP_LOCK_ASSERT(pmap, MA_OWNED);

	PG_A = pmap_accessed_bit(pmap);
	PG_M = pmap_modified_bit(pmap);
	PG_V = pmap_valid_bit(pmap);
	PG_RW = pmap_rw_bit(pmap);

	/*
	 * Allocate a page table page.
	 */
	if ((m = vm_page_alloc(NULL, ptepindex, VM_ALLOC_NOOBJ |
	    VM_ALLOC_WIRED | VM_ALLOC_ZERO)) == NULL)
		return (NULL);
	if ((m->flags & PG_ZERO) == 0)
		pmap_zero_page(m);

	/*
	 * Map the pagetable page into the process address space, if
	 * it isn't already there.
	 */
	if (ptepindex >= NUPDE + NUPDPE + NUPML4E) {
		MPASS(pmap_is_la57(pmap));

		pml5index = pmap_pml5e_index(va);
		pml5 = &pmap->pm_pmltop[pml5index];
		KASSERT((*pml5 & PG_V) == 0,
		    ("pmap %p va %#lx pml5 %#lx", pmap, va, *pml5));
		*pml5 = VM_PAGE_TO_PHYS(m) | PG_U | PG_RW | PG_V | PG_A | PG_M;

		if (pmap->pm_pmltopu != NULL && pml5index < NUPML5E) {
			if (pmap->pm_ucr3 != PMAP_NO_CR3)
				*pml5 |= pg_nx;

			pml5u = &pmap->pm_pmltopu[pml5index];
			*pml5u = VM_PAGE_TO_PHYS(m) | PG_U | PG_RW | PG_V |
			    PG_A | PG_M;
		}
	} else if (ptepindex >= NUPDE + NUPDPE) {
		pml4index = pmap_pml4e_index(va);
		/* Wire up a new PDPE page */
		pml4 = pmap_allocpte_getpml4(pmap, lockp, va, true);
		if (pml4 == NULL) {
			vm_page_unwire_noq(m);
			vm_page_free_zero(m);
			return (NULL);
		}