1 files changed, 79 insertions, 35 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 1eb7768..2cb769d 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -4704,52 +4704,96 @@ pmap_object_init_pt(pmap_t pmap, vm_offset_t addr, vm_object_t object,
 }
 
 /*
- *	Routine:	pmap_change_wiring
- *	Function:	Change the wiring attribute for a map/virtual-address
- *			pair.
- *	In/out conditions:
- *			The mapping must already exist in the pmap.
+ *	Clear the wired attribute from the mappings for the specified range of
+ *	addresses in the given pmap.  Every valid mapping within that range
+ *	must have the wired attribute set.  In contrast, invalid mappings
+ *	cannot have the wired attribute set, so they are ignored.
+ *
+ *	The wired attribute of the page table entry is not a hardware feature,
+ *	so there is no need to invalidate any TLB entries.
  */
 void
-pmap_change_wiring(pmap_t pmap, vm_offset_t va, boolean_t wired)
+pmap_unwire(pmap_t pmap, vm_offset_t sva, vm_offset_t eva)
 {
+	vm_offset_t va_next;
+	pml4_entry_t *pml4e;
+	pdp_entry_t *pdpe;
 	pd_entry_t *pde;
-	pt_entry_t *pte;
+	pt_entry_t *pte, PG_V;
 	boolean_t pv_lists_locked;
 
+	PG_V = pmap_valid_bit(pmap);
 	pv_lists_locked = FALSE;
-
-	/*
-	 * Wiring is not a hardware characteristic so there is no need to
-	 * invalidate TLB.
-	 */
-retry:
+resume:
 	PMAP_LOCK(pmap);
-	pde = pmap_pde(pmap, va);
-	if ((*pde & PG_PS) != 0) {
-		if (!wired != ((*pde & PG_W) == 0)) {
-			if (!pv_lists_locked) {
-				pv_lists_locked = TRUE;
-				if (!rw_try_rlock(&pvh_global_lock)) {
-					PMAP_UNLOCK(pmap);
-					rw_rlock(&pvh_global_lock);
-					goto retry;
+	for (; sva < eva; sva = va_next) {
+		pml4e = pmap_pml4e(pmap, sva);
+		if ((*pml4e & PG_V) == 0) {
+			va_next = (sva + NBPML4) & ~PML4MASK;
+			if (va_next < sva)
+				va_next = eva;
+			continue;
+		}
+		pdpe = pmap_pml4e_to_pdpe(pml4e, sva);
+		if ((*pdpe & PG_V) == 0) {
+			va_next = (sva + NBPDP) & ~PDPMASK;
+			if (va_next < sva)
+				va_next = eva;
+			continue;
+		}
+		va_next = (sva + NBPDR) & ~PDRMASK;
+		if (va_next < sva)
+			va_next = eva;
+		pde = pmap_pdpe_to_pde(pdpe, sva);
+		if ((*pde & PG_V) == 0)
+			continue;
+		if ((*pde & PG_PS) != 0) {
+			if ((*pde & PG_W) == 0)
+				panic("pmap_unwire: pde %#jx is missing PG_W",
+				    (uintmax_t)*pde);
+
+			/*
+			 * Are we unwiring the entire large page?  If not,
+			 * demote the mapping and fall through.
+			 */
+			if (sva + NBPDR == va_next && eva >= va_next) {
+				atomic_clear_long(pde, PG_W);
+				pmap->pm_stats.wired_count -= NBPDR /
+				    PAGE_SIZE;
+				continue;
+			} else {
+				if (!pv_lists_locked) {
+					pv_lists_locked = TRUE;
+					if (!rw_try_rlock(&pvh_global_lock)) {
+						PMAP_UNLOCK(pmap);
+						rw_rlock(&pvh_global_lock);
+						/* Repeat sva. */
+						goto resume;
+					}
 				}
+				if (!pmap_demote_pde(pmap, pde, sva))
+					panic("pmap_unwire: demotion failed");
 			}
-			if (!pmap_demote_pde(pmap, pde, va))
-				panic("pmap_change_wiring: demotion failed");
-		} else
-			goto out;
-	}
-	pte = pmap_pde_to_pte(pde, va);
-	if (wired && (*pte & PG_W) == 0) {
-		pmap->pm_stats.wired_count++;
-		atomic_set_long(pte, PG_W);
-	} else if (!wired && (*pte & PG_W) != 0) {
-		pmap->pm_stats.wired_count--;
-		atomic_clear_long(pte, PG_W);
+		}
+		if (va_next > eva)
+			va_next = eva;
+		for (pte = pmap_pde_to_pte(pde, sva); sva != va_next; pte++,
+		    sva += PAGE_SIZE) {
+			if ((*pte & PG_V) == 0)
+				continue;
+			if ((*pte & PG_W) == 0)
+				panic("pmap_unwire: pte %#jx is missing PG_W",
+				    (uintmax_t)*pte);
+
+			/*
+			 * PG_W must be cleared atomically.  Although the pmap
+			 * lock synchronizes access to PG_W, another processor
+			 * could be setting PG_M and/or PG_A concurrently.
+			 */
+			atomic_clear_long(pte, PG_W);
+			pmap->pm_stats.wired_count--;
+		}
 	}
-out:
 	if (pv_lists_locked)
 		rw_runlock(&pvh_global_lock);
 	PMAP_UNLOCK(pmap);