University of Cambridge
Contemporary CPU architectures conflate virtualization and protection, imposing virtualization-related performance, programmability, and debuggability penalties on software requiring fine-grained protection. First observed in micro-kernel research, these problems are increasingly apparent in recent attempts to mitigate software vulnerabilities through application compartmentalisation. Capability Hardware Enhanced RISC Instructions (CHERI) extend RISC ISAs to support greater software compartmentalisation. CHERI's hybrid capability model provides fine-grained compartmentalisation within address spaces while maintaining software backward compatibility, which will allow the incremental deployment of fine-grained compartmentalisation in both the authors' most trusted and least trustworthy C-language software stacks.