This leads us to make very different often counterintuitive choices to other stms, and allows our algorithm to cause very little additional cache contention overhead, relative to a nontransactional program. Pdf timebased software transactional memory researchgate. Pdf software transactional memory stm is a concurrency control mechanism that is widely. Second, at least the current hardware implementations of transactional memory are limited.
Protecting private keys against memory disclosure attacks. Intel clear video hd technology, like its predecessor, intel clear video technology, is a suite of image decode and processing technologies built into the integrated processor graphics that improve video playback, delivering cleaner, sharper images, more natural, accurate, and vivid colors, and a clear and stable video picture. When run on our 106processor test machine, our algorithm is almost five times as fast as the previous. Researchers have proposed several different implementations of transactional memory, broadly classified into software transactional memory stm and hardware transactional memory htm. A transaction in this context is a piece of code that executes a series of reads and writes to shared memory. Software transactional memory stm systems have emerged as a powerful paradigm to. Feb 17, 2005 software transactional memory stm is an api for multithreaded computation in which shared data is synchronized without using locks. Apache ignite is an open source inmemory data fabric which provides a wide variety of computing solutions including an inmemory data grid, compute grid, streaming, as well as acceleration solutions for hadoop and spark. Most web browsers use a cache to load regularly viewed webpages fast. Software transactional memory wikipedia, the free encyclopedia. Architectural support for software transactional memory.
Both caches are primary caches accessed directly by the processor, and secondary caches may exist between them andthe memory. Threads synchronize by means of memory transactions, shortlived computations that either commit take effect or abort have no effect. Unfortunately, there isnt a released, working, usable framework for this yet. We classify what kinds of spare aborts can be eliminated, and which cannot. The simulator models a multiprocessor system, where each processor has a variable sized l1 4way associative lru cache. This optimization improves the memory cache hit rate if the. A softwarelevel solution leveraging hardware transactional memory features in commodity processor to enable a program to protect itself from a wide range of cache sidechannel attacks. Stm is a strategy implemented in software, rather than as a hardware component. The cache coherence simulator simulates a multiprocessor snoopingbased system that uses the mesi cache coherence protocol with a split transaction bus. Single copy distributed software transactional memory protocol maintains only one replica of each object in the system and is therefore prone to failures in.
Abstract cachebased sidechannel attacks are a serious problem in multitenant environments, for example, modern cloud data centers. Software transactional memory ransactionalt locking ii dice et. However, the fragility of tsx transactions introduces extra cacheclogging denialofservice dos threats, and attackers could sharply degrade the performance by concurrent memoryintensive tasks. Localitysensitive signatures for transactional memory conference paper pdf available in ieee transactions on computers 622.
Especially the chapter about performance is also important for using stm in rust. Transactional memory is just as complex as simultaneous multithreading, and intels smt was specifically designed so that it could be disabled in early versions e. Not be obstructionfree cache sensitive software transactional memory. Probe, flushreload, evicttime, cachecollision attacks.
A software transactional memory stm is a shared object which behaves like a memory that supports muldequeue begintransaction deleteditemread transactional head if deleteditemnull returnedvalueempty else. This library implements software transactional memory, often abbreviated with stm it is designed closely to haskells stm library. We show that cloak provides strong protection against all known cachebased sidechannel attacks with low performance overhead. Raccoon 58 attempts to hide accesses to developerannotated data. Cloak 28 uses transactional memory to render an attackers cache observations oblivious, before accessing sensitive memory content all cache lines are accessed. A programs use of cpu caches may reveal its memory access pattern and thus leak sensitive information when the program performs secretdependent. For the haswell microarchitecture the scope of a transaction is limited, because the readwrite set, i. Transactional memory is a programming model that attempts to make parallel programming easier. Single copy distributed software transactional memory protocol maintains only one replica of each object in the system and is therefore prone to failures in large scale dynamically changing network. Cache based sidechannel attacks are a serious problem in multitenant environments, for example, modern cloud data centers. It is the first to integrate a software transactional memory system with a mallocfree based memory allocator.
Leveraging hardware transactional memory for cache side. When run on our 106processor test machine, our algorithm is almost five times as fast as the previous best known algorithm. Decoupling hardware transactional memory from caches. For all three memory systems, performance with the generated. Usenix security 17 strong and efficient cache side. Transactions avoid the wellknown problems of locking, including deadlock. Should not be obstructionfree and cache sensitive software transactional memory.
We further study what kinds of spare aborts can be avoided. Logtmse achieves this using an additional summary signature per thread context to sum. This library implements software transactional memory, often abbreviated with stm. Existing tms may abort many transactions that could, in fact, commit without violating correctness.
Typical implementations use hardware transactional memory where supported and to the limits that it is available e. Multiversioning in transactional memory request pdf. In computer science, software transactional memory stm is a concurrency control mechanism analogous to database transactions for controlling access to shared memory in concurrent computing. Performance modelling of hardware transactional memory. To the best of our knowledge, mimosa is the first to use transactional memory to protect sensitive data against memory attacks. Therein he describes a hardware based transactional memory system. Software transactional memory stm is an api for multithreaded computation in which shared data is synchronized without using locks. The idea to implement memory operations in a transactional way originates from a 1986 patent by tom knight 1.
Cache memory is a type of memory used to hold frequently used data. In particular, we use intel transactional synchronization extensions tsx 40, a commodity implementation of htm in commercialofftheshelf cots platforms. Transactions avoid many of these problems, and therefore, promise to ease concurrent programming. Apache spark is an open source fast and general engine for largescale data processing. Then, the process uses an nonblocking kword readmodify write atomic operation which checks if the values contained in the memory are equivalent to the the value read in the cache update. Localitysensitive signatures for transactional memory. Especially the chapter about performance is also important for using stm in rust with locks the sequential. However, the fragility of tsx transactions introduces extra cache clogging denialofservice dos threats, and attackers could sharply degrade the performance. Thus this paper describes a memory allocator that is suitable for emerging multicore applications, while supporting modern concurrency constructs. Similarly, the ability to save and restore signatures allows unbounded nesting. Cache sensitive software transactional memory core. The tcc system is described in detail in section 2 of this paper, and compared further with stateoftheart coherence and consis. Previous hardware tm systems were plagued by associativity conflicts, which intel probably dealt with by using the l2 cache for transactional data. The lightweight transaction library libltx, a c implementation by robert ennals focusing on efficiency and based on his papers software transactional memory should not be obstructionfree and cache sensitive software transactional memory.
Usenix security 17 strong and efficient cache sidechannel. We address this problem with cloak, a new technique that uses hardware transactional memory to prevent adversarial observation of cache misses on sensitive code and data. Transactional memory uses either eager at encounter time or lazy at commit time validation to check for conflicting accesses between concurrent transactions, and researchers have been divided over which approach is best. We describe a software transactional memory stm system that is part of mcrt, an experimental multicore runtime. We show that cloak provides strong protection against all known cache based sidechannel attacks with low performance overhead. This paper takes a step toward developing a theory for understanding aborts in transactional memory systems tms. Method hardware transactional memory provides a way for victim application to detect and get control to protect itself proactively when its data is evicted out of cache. Replacing conventional, cache line oriented coherence protocols and conventional shared memory consistency models with a transactional memory coherence and consistency tcc model can accomplish this. We present a new algorithm for implementing object based software transactional memory stm that we have found to significantly outperform the previous best performing algorithms. Tsx abort operations can return a code that indicates the proximate cause, to help diagnosing hardware and software bugs, and debugger support is an integral part of the specification. This effectively conceals cache accesspatterns from attackers and keeps the performance impact low. Make use of this cache by setting expire header and etag.
In the current architecture of the fenixedu system, every. Spark is for nontransactional, readonly data rdds dont support inplace mutation, while ignite supports both nontransactional olap payloads as well as fully acid compliant. However, the fragility of tsx transactions introduces extra cacheclogging denialofservice dos threats, and attackers could sharply degrade the performance. Software transactional memory should not be obstructionfree cache sensitive software transactional. Method hardware transactional memory provides a way for victim application to detect and get control to protect itself proactively when its data is. Inoursimulations,theregular cache is a conventional directmapped cache. Exploiting hardware transactional memory in mainmemory. Replacing conventional, cacheline oriented coherence protocols and conventional shared memory consistency models with a transactional memory coherence and consistency tcc model can accomplish this.
It sounds like youre remembering the discussion of software transactional memory from. Cloak relies on the sgx enclave developer to annotate sensitive memory. Both old and new versions of memory can be victimized transparently because the cache holds no inaccessible transactional state. Johannes schneider march 16 th, 2011 ioana giurgiu softwrae transactional memory. We ensure permanent cache residency of sensitive code and data using widely available hardware transactional memory htm, which was originally designed for highperformance concurrency. Citeseerx document details isaac councill, lee giles, pradeep teregowda. The approach described in this paper, software transactional memory stm, enables developers to operate on the memory in a similar way to using database transactions.
Many cache side channel attacks involve adversary evicting victims cache lines during the execution of sensitive operations. Strong and efficient cache sidechannel protection using. We achieve this by taking care to minimise cache contention and memorybandwidth requirements. A software transactional memory stm is a shared object which behaves like a memory that supports muldequeue begintransaction deleteditemreadtransactionalhead if deleteditemnull returnedvalueempty else ritetransactionalhead, deleteditemc. Overall, haswell is more likely to use the cachebased tm system. When run on our 106processor test machine, our algorithm is almost five times. Transactional memory provides a concurrency control mechanism that avoids many of the pitfalls of lockbased synchronization. Jun 20, 2016 ignite, on the other hand, provides a distributed inmemory keyvalue store distributed cache or data grid with acid transactions and sql querying capabilities. Software transactional memory wikimili, the best wikipedia. Libcmt, an opensource implementation in c by duilio protti based on composable memory transactions. The overhead for using this design approach was small.
To the best of our knowledge, mimosa is the first to use transactional memory to protect sensitive. Software transactional memory stm is a mechanism used to coordinate. We show that cloak provides strong protection against all known. Case studies of applying the solution to the aes, rsa and.
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