Aggressive memory density scaling causes modern DRAM devices to suffer from RowHammer, a phenomenon where rapidly activating a DRAM row can cause bit-flips in physically-nearby rows. Recent studies demonstrate that modern DRAM chips, including chips previously marketed as RowHammer-safe, are even more vulnerable to RowHammer than older chips. Many works show that attackers can exploit RowHammer bit-flips to reliably mount system-level attacks to escalate privilege and leak private data. Therefore, it is critical to ensure RowHammer-safe operation on all DRAM-based systems. Unfortunately, state-of-the-art RowHammer mitigation mechanisms face two major challenges. First, they incur increasingly higher performance and/or area overheads when applied to more vulnerable DRAM chips. Second, they require either proprietary information about or modifications to the DRAM chip design. In this paper, we show that it is possible to efficiently and scalably prevent RowHammer bit-flips without knowledge of or modification to DRAM internals. We introduce BlockHammer, a low-cost, effective, and easy-to-adopt RowHammer mitigation mechanism that overcomes the two key challenges by selectively throttling memory accesses that could otherwise cause RowHammer bit-flips. The key idea of BlockHammer is to (1) track row activation rates using area-efficient Bloom filters and (2) use the tracking data to ensure that no row is ever activated rapidly enough to induce RowHammer bit-flips. By doing so, BlockHammer (1) makes it impossible for a RowHammer bit-flip to occur and (2) greatly reduces a RowHammer attack's impact on the performance of co-running benign applications. Compared to state-of-the-art RowHammer mitigation mechanisms, BlockHammer provides competitive performance and energy when the system is not under a RowHammer attack and significantly better performance and energy when the system is under attack.

中文翻译：

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BlockHammer：通过将快速访问的DRAM行列入黑名单，以低成本防止RowHammer

激进的存储器密度缩放使现代DRAM设备遭受RowHammer的折磨，这种现象是快速激活DRAM行会导致物理上相邻的行发生位翻转。最近的研究表明，现代DRAM芯片（包括以前以RowHammer-safe形式销售的芯片）比旧式芯片更容易受到RowHammer的攻击。许多工作表明，攻击者可以利用RowHammer的位翻转来可靠地进行系统级攻击，以提升特权并泄漏私人数据。因此，确保所有基于DRAM的系统上的RowHammer安全操作至关重要。不幸的是，最先进的RowHammer缓解机制面临两个主要挑战。首先，当将它们应用于更脆弱的DRAM芯片时，它们会带来越来越高的性能和/或面积开销。第二，它们需要有关DRAM芯片设计的专有信息或进行修改。在本文中，我们表明，无需了解或修改DRAM内部结构，就可以有效且可扩展地防止RowHammer位翻转。我们介绍了BlockHammer，这是一种低成本，有效且易于采用的RowHammer缓解机制，通过有选择地限制可能导致RowHammer比特翻转的内存访问，克服了两个关键挑战。BlockHammer的关键思想是（1）使用面积效率高的Bloom过滤器跟踪行激活速率，以及（2）使用跟踪数据来确保没有足够快的行被激活以引起RowHammer比特翻转。这样，BlockHammer（1）使得RowHammer的位翻转不可能发生，而（2）大大减少了RowHammer的攻击。对共同运行的良性应用程序的性能的影响。与最新的RowHammer缓解机制相比，BlockHammer在系统未受到RowHammer攻击时可提供具有竞争力的性能和能量，而在系统受到攻击时则可提供更好的性能和能量。