xnu-1699.24.23.tar.gz

[apple/xnu.git] / osfmk / vm / vm_pageout.c

diff --git a/osfmk/vm/vm_pageout.c b/osfmk/vm/vm_pageout.c
index acf4d64bd21732a4cc4f8a3c37be5f2cfe2b3a0b..0761db5ef7d56dff14dcfa13d52c2d5144980662 100644 (file)
--- a/osfmk/vm/vm_pageout.c
+++ b/osfmk/vm/vm_pageout.c
@@ -3956,10 +3956,30 @@ REDISCOVER_ENTRY:
 
                        return KERN_SUCCESS;
                }
+
+               if (entry->is_sub_map) {
+                       vm_map_t        submap;
+
+                       submap = entry->object.sub_map;
+                       local_start = entry->vme_start;
+                       local_offset = entry->offset;
+
+                       vm_map_reference(submap);
+                       vm_map_unlock_read(map);
+
+                       ret = vm_map_create_upl(submap, 
+                                               local_offset + (offset - local_start), 
+                                               upl_size, upl, page_list, count, flags);
+                       vm_map_deallocate(submap);
+
+                       return ret;
+               }
+
                if (entry->object.vm_object == VM_OBJECT_NULL || !entry->object.vm_object->phys_contiguous) {
                        if ((*upl_size/PAGE_SIZE) > MAX_UPL_SIZE)
                                        *upl_size = MAX_UPL_SIZE * PAGE_SIZE;
                }
+
                /*
                 *      Create an object if necessary.
                 */
@@ -3978,6 +3998,42 @@ REDISCOVER_ENTRY:
                                vm_map_unlock_read(map);
                                return KERN_PROTECTION_FAILURE;
                        }
+
+#if !CONFIG_EMBEDDED
+                       local_object = entry->object.vm_object;
+                       if (vm_map_entry_should_cow_for_true_share(entry) &&
+                           local_object->vo_size > *upl_size &&
+                           *upl_size != 0) {
+                               vm_prot_t       prot;
+
+                               /*
+                                * Set up the targeted range for copy-on-write to avoid
+                                * applying true_share/copy_delay to the entire object.
+                                */
+
+                               if (vm_map_lock_read_to_write(map)) {
+                                       goto REDISCOVER_ENTRY;
+                               }
+
+                               vm_map_clip_start(map, entry, vm_map_trunc_page(offset));
+                               vm_map_clip_end(map, entry, vm_map_round_page(offset + *upl_size));
+                               prot = entry->protection & ~VM_PROT_WRITE;
+                               if (override_nx(map, entry->alias) && prot)
+                                       prot |= VM_PROT_EXECUTE;
+                               vm_object_pmap_protect(local_object,
+                                                      entry->offset,
+                                                      entry->vme_end - entry->vme_start,
+                                                      ((entry->is_shared || map->mapped)
+                                                       ? PMAP_NULL
+                                                       : map->pmap),
+                                                      entry->vme_start,
+                                                      prot);
+                               entry->needs_copy = TRUE;
+
+                               vm_map_lock_write_to_read(map);
+                       }
+#endif /* !CONFIG_EMBEDDED */
+
                        if (entry->needs_copy)  {
                                /*
                                 * Honor copy-on-write for COPY_SYMMETRIC
@@ -4012,23 +4068,6 @@ REDISCOVER_ENTRY:
                                goto REDISCOVER_ENTRY;
                        }
                }
-               if (entry->is_sub_map) {
-                       vm_map_t        submap;
-
-                       submap = entry->object.sub_map;
-                       local_start = entry->vme_start;
-                       local_offset = entry->offset;
-
-                       vm_map_reference(submap);
-                       vm_map_unlock_read(map);
-
-                       ret = vm_map_create_upl(submap, 
-                                               local_offset + (offset - local_start), 
-                                               upl_size, upl, page_list, count, flags);
-                       vm_map_deallocate(submap);
-
-                       return ret;
-               }
                if (sync_cow_data) {
                        if (entry->object.vm_object->shadow || entry->object.vm_object->copy) {
                                local_object = entry->object.vm_object;