def iadd(self, old, args, value):
assert len(args) == 2
assert value == 1
ref, perm, perm_inv = old
refval = ref(args[0])
owned = perm(args[0], refval)
idx = perm_inv(args[0], args[1])
ref = util.partial_update(ref, (args[0],), refval + 1)
# We are modeling the ownership with three functions,
# 1) a refcount number: the number of objects owned by `owner`
# 2) a function with the property that the first `refval` objects owned by `owner`
# 3) a function that is the inverse of 2)
# For example, consider 5 'ownable' objects in the system,
# Where `owner` has 2 objects: 3 and 2. The state might look like:
#--------------------------
# 3 | 2 | 1 | 4 | 5
#--------------------------
# ^
# refval
# Now, iadd is incrementing the refcnt by allocating args[2]
# To do this we have to swap the current position of args[2] with the
# Slot at refval.
# For example, if args[1] is 5, we update the state by swapping the `1`
# at index refval with the index of args[1].
#--------------------------
# 3 | 2 | 5 | 4 | 1
#--------------------------
# ^
# refval
# Write the new value (args[1]) into position refval and maintain the
# inverse function
perm = util.partial_update(perm, (args[0], refval), args[1])
perm_inv = util.partial_update(perm_inv, (args[0], args[1]), refval)
# Write the previous value of refval to the previous location of args[1]
perm = util.partial_update(perm, (args[0], idx), owned)
perm_inv = util.partial_update(perm_inv, (args[0], owned), idx)
return (ref, perm, perm_inv)
def isub(self, old, args, value):
assert len(args) == 2
assert value == 1
ref, perm, perm_inv = old
ref = util.partial_update(ref, (args[0],), ref(args[0]) - 1)
refval = ref(args[0])
owned = perm(args[0], refval)
idx = perm_inv(args[0], args[1])
perm = util.partial_update(perm, (args[0], refval), args[1])
perm_inv = util.partial_update(perm_inv, (args[0], args[1]), refval)
perm = util.partial_update(perm, (args[0], idx), owned)
perm_inv = util.partial_update(perm_inv, (args[0], owned), idx)
return (ref, perm, perm_inv)
def set(self, old, args, value):
# "raw" assignment of a lambda without any accessor arguments
if isinstance(value, types.FunctionType):
assert not args
return lambda *args: value(*args, oldfn=old)
elif self.get_arity() == 0:
# assignment to a value
return value
else:
# assignment with value with partial arguments
return util.partial_update(old, args, value)
def isub(self, old, args, value):
assert len(args) == 2
assert value == 1
ref, perm1, perm2, perm_inv = old
ref = util.partial_update(ref, (args[0],), ref(args[0]) - 1)
refval = ref(args[0])
owned_x = perm1(args[0], refval)
owned_y = perm2(args[0], refval)
idx = perm_inv(args[0], *args[1])
perm1 = util.partial_update(perm1, (args[0], refval), args[1][0])
perm2 = util.partial_update(perm2, (args[0], refval), args[1][1])
perm_inv = util.partial_update(perm_inv, (args[0], args[1][0], args[1][1]), refval)
perm1 = util.partial_update(perm1, (args[0], idx), owned_x)
perm2 = util.partial_update(perm2, (args[0], idx), owned_y)
perm_inv = util.partial_update(perm_inv, (args[0], owned_x, owned_y), idx)
return (ref, perm1, perm2, perm_inv)
def hvm_invalidate_tlb(ctx, pid):
uf = ctx.globals['#tlbinv']
ctx.globals['#tlbinv'] = util.partial_update(uf, (pid, ), z3.BoolVal(True))