Change Details

``` It is possible that VA right before the current anonymous clustering location was unmapped, e.g. this could happen when the malloc allocations interleave with explicit mmaps of the anonymous memory, and frees/unmaps. In this case, try to compact the clustering allocations by starting not from map->anon_loc, but at the end of the map entry right below it. This should make no change in alloc effects for cases where no free of the anon memory occurs. The only overhead I see is from the additional splay for vm_map entry tree. ```

``` It is possible that VA right before the current anonymous clustering location was unmapped, e.g. this could happen when the malloc allocations interleave with explicit mmaps of the anonymous memory, and frees/unmaps. Mark anon mappings with a new map entry flag MAP_ENTRY_ANON_LOC_UPD, and update the map->anon_loc with the previous entry' end if freed entry is flagged. ``` ``` ASLR: add a new mode for anonymous clustering control The value 3 for vm.cluster_anon still initializes the clustering point at the image creation, and never update it. So, all virtual address allocations are performed using an address-ordered, first-fit policy, just like we do when ASLR is turned off. ``` ``` vm_map_find(): the address hint is almost always non-zero Adopt to the observation and fix cluster mode 1 by enabling clustering if hint is zero or less then current clustering location. ```

``` It is possible that VA right before the current anonymous clustering location was unmapped, e.g. this could happen when the malloc allocations interleave with explicit mmaps of the anonymous memory, and frees/unmaps. In this case, try to compact the clustering allocations by starting not fromMark anon mappings with a new map->anon_loc entry flag MAP_ENTRY_ANON_LOC_UPD, but at the end of the map entry rightand below it.update the map->anon_loc with the previous entry' end if freed entry is flagged. ``` ``` ASLR: add a new mode for anonymous clustering control This should make no change in alloc effects for cases where no free ofThe value 3 for vm.cluster_anon still initializes the clustering point the anon memory occurs. The only overhead I see is from theat the image creation, and never update it. So, all virtual additionalress splay for vm_map entry treeallocations are performed using an address-ordered, first-fit policy, just like we do when ASLR is turned off. ``` ``` vm_map_find(): the address hint is almost always non-zero Adopt to the observation and fix cluster mode 1 by enabling clustering if hint is zero or less then current clustering location. ```