18 research outputs found
Completeness for a First-order Abstract Separation Logic
Existing work on theorem proving for the assertion language of separation
logic (SL) either focuses on abstract semantics which are not readily available
in most applications of program verification, or on concrete models for which
completeness is not possible. An important element in concrete SL is the
points-to predicate which denotes a singleton heap. SL with the points-to
predicate has been shown to be non-recursively enumerable. In this paper, we
develop a first-order SL, called FOASL, with an abstracted version of the
points-to predicate. We prove that FOASL is sound and complete with respect to
an abstract semantics, of which the standard SL semantics is an instance. We
also show that some reasoning principles involving the points-to predicate can
be approximated as FOASL theories, thus allowing our logic to be used for
reasoning about concrete program verification problems. We give some example
theories that are sound with respect to different variants of separation logics
from the literature, including those that are incompatible with Reynolds's
semantics. In the experiment we demonstrate our FOASL based theorem prover
which is able to handle a large fragment of separation logic with heap
semantics as well as non-standard semantics.Comment: This is an extended version of the APLAS 2016 paper with the same
titl
Leaf: Modularity for Temporary Sharing in Separation Logic (Extended Version)
In concurrent verification, separation logic provides a strong story for
handling both resources that are owned exclusively and resources that are
shared persistently (i.e., forever). However, the situation is more complicated
for temporarily shared state, where state might be shared and then later
reclaimed as exclusive. We believe that a framework for temporarily-shared
state should meet two key goals not adequately met by existing techniques. One,
it should allow and encourage users to verify new sharing strategies. Two, it
should provide an abstraction where users manipulate shared state in a way
agnostic to the means with which it is shared.
We present Leaf, a library in the Iris separation logic which accomplishes
both of these goals by introducing a novel operator, which we call guarding,
that allows one proposition to represent a shared version of another. We
demonstrate that Leaf meets these two goals through a modular case study: we
verify a reader-writer lock that supports shared state, and a hash table built
on top of it that uses shared state
Composing Interfering Abstract Protocols
The undisciplined use of shared mutable state can be a source of program errors when aliases unsafely interfere with each other.
While protocol-based techniques to reason about interference abound, they do not address two practical concerns: the decidability of protocol composition and its integration with protocol abstraction.
We show that our composition procedure is decidable and that it ensures safe interference even when composing abstract protocols.
To evaluate the expressiveness of our protocol framework for safe shared memory interference, we show how this same protocol framework can be used to model safe, typeful message-passing concurrency idioms
SteelCore: An extensible concurrent separation logic for effectful dependently typed programs
Much recent research has been devoted to modeling effects within type theory. Building on this work, we observe that effectful type theories can provide a foundation on which to build semantics for more complex programming constructs and program logics, extending the reasoning principles that apply within the host effectful type theory itself. Concretely, our main contribution is a semantics for concurrent separation logic (CSL) within the F* proof assistant in a manner that enables dependently typed, effectful F* programs to make use of concurrency and to be specified and verified using a full-featured, extensible CSL. In contrast to prior approaches, we directly derive the partial-correctness Hoare rules for CSL from the denotation of computations in the effectful semantics of non-deterministically interleaved atomic actions. Demonstrating the flexibility of our semantics, we build generic, verified libraries that support various concurrency constructs, ranging from dynamically allocated, storable spin locks, to protocol-indexed channels. We conclude that our effectful semantics provides a simple yet expressive basis on which to layer domain-specific languages and logics for verified, concurrent programming.Fil: Swamy, Nikhil. Microsoft Research; Estados UnidosFil: Rastogi, Aseem. Microsoft Research; IndiaFil: Fromherz, Aymeric. University of Carnegie Mellon; Estados UnidosFil: Merigoux, Denis. Institut National de Recherche en Informatique et en Automatique; FranciaFil: Ahman, Danel. University of Ljubljana; EsloveniaFil: MartÃnez, Guido. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas. Universidad Nacional de Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y de Sistemas; Argentin