Function pmap_advise

freebsd/arm64/arm64/pmap.c:5656–5782

* Apply the given advice to the specified range of addresses within the * given pmap. Depending on the advice, clear the referenced and/or * modified flags in each mapping and set the mapped page's dirty field. */

 *	modified flags in each mapping and set the mapped page's dirty field.
 */
void
pmap_advise(pmap_t pmap, vm_offset_t sva, vm_offset_t eva, int advice)
{
	struct rwlock *lock;
	vm_offset_t va, va_next;
	vm_page_t m;
	pd_entry_t *l0, *l1, *l2, oldl2;
	pt_entry_t *l3, oldl3;

	PMAP_ASSERT_STAGE1(pmap);

	if (advice != MADV_DONTNEED && advice != MADV_FREE)
		return;

	PMAP_LOCK(pmap);
	for (; sva < eva; sva = va_next) {
		l0 = pmap_l0(pmap, sva);
		if (pmap_load(l0) == 0) {
			va_next = (sva + L0_SIZE) & ~L0_OFFSET;
			if (va_next < sva)
				va_next = eva;
			continue;
		}

		va_next = (sva + L1_SIZE) & ~L1_OFFSET;
		if (va_next < sva)
			va_next = eva;
		l1 = pmap_l0_to_l1(l0, sva);
		if (pmap_load(l1) == 0)
			continue;
		if ((pmap_load(l1) & ATTR_DESCR_MASK) == L1_BLOCK) {
			KASSERT(va_next <= eva,
			    ("partial update of non-transparent 1G page "
			    "l1 %#lx sva %#lx eva %#lx va_next %#lx",
			    pmap_load(l1), sva, eva, va_next));
			continue;
		}

		va_next = (sva + L2_SIZE) & ~L2_OFFSET;
		if (va_next < sva)
			va_next = eva;
		l2 = pmap_l1_to_l2(l1, sva);
		oldl2 = pmap_load(l2);
		if (oldl2 == 0)
			continue;
		if ((oldl2 & ATTR_DESCR_MASK) == L2_BLOCK) {
			if ((oldl2 & ATTR_SW_MANAGED) == 0)
				continue;
			lock = NULL;
			if (!pmap_demote_l2_locked(pmap, l2, sva, &lock)) {
				if (lock != NULL)
					rw_wunlock(lock);

				/*
				 * The 2MB page mapping was destroyed.
				 */
				continue;
			}