Function pmap_clear_modify

freebsd/arm/arm/pmap-v6.c:5674–5737

* Clear the modify bits on the specified physical page. */

 *	Clear the modify bits on the specified physical page.
 */
void
pmap_clear_modify(vm_page_t m)
{
	struct md_page *pvh;
	pv_entry_t next_pv, pv;
	pmap_t pmap;
	pt1_entry_t *pte1p, opte1;
	pt2_entry_t *pte2p, opte2;
	vm_offset_t va;

	KASSERT((m->oflags & VPO_UNMANAGED) == 0,
	    ("%s: page %p is not managed", __func__, m));
	vm_page_assert_busied(m);

	if (!pmap_page_is_write_mapped(m))
		return;
	rw_wlock(&pvh_global_lock);
	sched_pin();
	if ((m->flags & PG_FICTITIOUS) != 0)
		goto small_mappings;
	pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
	TAILQ_FOREACH_SAFE(pv, &pvh->pv_list, pv_next, next_pv) {
		va = pv->pv_va;
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pte1p = pmap_pte1(pmap, va);
		opte1 = pte1_load(pte1p);
		if (!(opte1 & PTE1_RO)) {
			if (pmap_demote_pte1(pmap, pte1p, va) &&
			    !pte1_is_wired(opte1)) {
				/*
				 * Write protect the mapping to a
				 * single page so that a subsequent
				 * write access may repromote.
				 */
				va += VM_PAGE_TO_PHYS(m) - pte1_pa(opte1);
				pte2p = pmap_pte2_quick(pmap, va);
				opte2 = pte2_load(pte2p);
				if ((opte2 & PTE2_V)) {
					pte2_set_bit(pte2p, PTE2_NM | PTE2_RO);
					vm_page_dirty(m);
					pmap_tlb_flush(pmap, va);
				}
			}
		}
		PMAP_UNLOCK(pmap);
	}
small_mappings:
	TAILQ_FOREACH(pv, &m->md.pv_list, pv_next) {
		pmap = PV_PMAP(pv);
		PMAP_LOCK(pmap);
		pte1p = pmap_pte1(pmap, pv->pv_va);
		KASSERT(!pte1_is_section(pte1_load(pte1p)), ("%s: found"
		    " a section in page %p's pv list", __func__, m));
		pte2p = pmap_pte2_quick(pmap, pv->pv_va);
		if (pte2_is_dirty(pte2_load(pte2p))) {
			pte2_set_bit(pte2p, PTE2_NM);
			pmap_tlb_flush(pmap, pv->pv_va);