Microarchitectural attacks pose an increasing threat to system security. They enable attackers to extract sensitive information such as cryptographic keys, website usage patterns, or keystrokes. Software-level defenses, such as constant-time implementations, mitigate some attack vectors but impose significant challenges on developers. Operating-system-level mitigations, such as page coloring and memory isolation, address these threats but require intricate kernel modifications and time-consuming workflows, making prototyping new defenses complex. In this paper, we present MAPAlloc (Microarchitectural Prototyping Allocator), a flexible, cross-architecture framework for rapidly prototyping memory allocation-based defenses and attacks on Linux systems. Using a simple domain-specific language, MAPAlloc allows for precise control over physical memory allocation on x86, ARMv8, and RISC-V. MAPAlloc enables quick implementation and evaluation of mitigations such as page coloring and novel techniques like layered page coloring, increasing the number of cache colors from 32 to 256 on modern CPUs. We demonstrate MAPAlloc's versatility through case studies that prevent Prime+Probe and DRAMA attacks and reverse-engineer the AMD Zen 4 complex cache-indexing function for use in layered page coloring. Additionally, we prototype a Prime+Probe attack with an incomplete non-linear slice function from previous work by limiting the physical memory using MAPAlloc. Without MAPAlloc, such defense and attack prototypes require complicated modifications of the Linux kernel, making them hard to develop and test. Thus, MAPAlloc is an essential framework for simplifying research in microarchitectural security.
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