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diff --git a/sys/vm/vm_map.h b/sys/vm/vm_map.h
--- a/sys/vm/vm_map.h
+++ b/sys/vm/vm_map.h
@@ -148,6 +148,7 @@
#define MAP_ENTRY_STACK_GAP_DN 0x00020000
#define MAP_ENTRY_STACK_GAP_UP 0x00040000
#define MAP_ENTRY_HEADER 0x00080000
+#define MAP_ENTRY_ANON_LOC_UPD 0x00400000
#define MAP_ENTRY_SPLIT_BOUNDARY_MASK 0x00300000
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -159,6 +159,12 @@
#define PROC_VMSPACE_LOCK(p) do { } while (0)
#define PROC_VMSPACE_UNLOCK(p) do { } while (0)
+static int cluster_anon = 1;
+SYSCTL_INT(_vm, OID_AUTO, cluster_anon, CTLFLAG_RW,
+ &cluster_anon, 0,
+ "Cluster anonymous mappings: "
+ "0 = no, 1 = yes if no hint, 2 = always, 3 = keep anon_loc const");
+
/*
* VM_MAP_RANGE_CHECK: [ internal use only ]
*
@@ -1700,6 +1706,12 @@
return (KERN_INVALID_ARGUMENT);
protoeflags |= bidx << MAP_ENTRY_SPLIT_BOUNDARY_SHIFT;
}
+ if (cluster_anon == 1 || cluster_anon == 2) {
+ if ((object == NULL || (cow & (MAP_INHERIT_SHARE |
+ MAP_STACK_GROWS_UP | MAP_STACK_GROWS_DOWN |
+ MAP_ENTRY_GUARD)) == 0) && max != PROT_NONE)
+ protoeflags |= MAP_ENTRY_ANON_LOC_UPD;
+ }
cred = NULL;
if ((cow & (MAP_ACC_NO_CHARGE | MAP_NOFAULT | MAP_CREATE_GUARD)) != 0)
@@ -1975,11 +1987,6 @@
static const int aslr_pages_rnd_64[2] = {0x1000, 0x10};
static const int aslr_pages_rnd_32[2] = {0x100, 0x4};
-static int cluster_anon = 1;
-SYSCTL_INT(_vm, OID_AUTO, cluster_anon, CTLFLAG_RW,
- &cluster_anon, 0,
- "Cluster anonymous mappings: 0 = no, 1 = yes if no hint, 2 = always");
-
static bool
clustering_anon_allowed(vm_offset_t addr, int cow)
{
@@ -1995,6 +2002,12 @@
}
}
+static bool
+clustering_anon_loc_const(void)
+{
+ return (cluster_anon == 3);
+}
+
static long aslr_restarts;
SYSCTL_LONG(_vm, OID_AUTO, aslr_restarts, CTLFLAG_RD,
&aslr_restarts, 0,
@@ -2226,7 +2239,7 @@
rv = vm_map_insert(map, object, offset, *addr, *addr + length,
prot, max, cow);
}
- if (rv == KERN_SUCCESS && update_anon)
+ if (rv == KERN_SUCCESS && update_anon && !clustering_anon_loc_const())
map->anon_loc = *addr + length;
done:
vm_map_unlock(map);
@@ -3970,8 +3983,9 @@
entry->object.vm_object != NULL)
pmap_map_delete(map->pmap, entry->start, entry->end);
- if (entry->end == map->anon_loc)
- map->anon_loc = entry->start;
+ if (entry->end == map->anon_loc &&
+ (entry->eflags & MAP_ENTRY_ANON_LOC_UPD) != 0)
+ map->anon_loc = vm_map_entry_pred(entry)->end;
/*
* Delete the entry only after removing all pmap

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