Rework memguard(9) to reserve significantly more KVA to detect

use-after-free over a longer time.  Also release the backing pages of
a guarded allocation at free(9) time to reduce the overhead of using
memguard(9).  Allow setting and varying the malloc type at run-time.
Add knobs to allow:

 - randomly guarding memory
 - adding un-backed KVA guard pages to detect underflow and overflow
 - a lower limit on the size of allocations that are guarded

Reviewed by:    alc
Reviewed by:    brueffer, Ulrich Spörlein <uqs spoerlein net> (man page)
Silence from:   -arch
Approved by:    zml (mentor)
MFC after:      1 month

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/vm/vm_extern.h b/sys/vm/vm_extern.h
index ca6d49c..8a0a400 100644
--- a/sys/vm/vm_extern.h
+++ b/sys/vm/vm_extern.h
@@ -53,6 +53,7 @@ void kmem_free(vm_map_t, vm_offset_t, vm_size_t);
 void kmem_free_wakeup(vm_map_t, vm_offset_t, vm_size_t);
 void kmem_init(vm_offset_t, vm_offset_t);
 vm_offset_t kmem_malloc(vm_map_t map, vm_size_t size, int flags);
+int kmem_back(vm_map_t, vm_offset_t, vm_size_t, int);
 vm_map_t kmem_suballoc(vm_map_t, vm_offset_t *, vm_offset_t *, vm_size_t,
     boolean_t);
 void swapout_procs(int);