Tagged memory and minion cores in the lowRISC SoC
The lowRISC project, which aims to create and manufacture a fully open-source system-on-chip (SoC) and development board, has released a document on its plans to incorporate tagged memory and minion cores into the SoC. Minion cores are separate I/O processors that can be used to implement various I/O protocols without requiring additional hardware in the design.
"Tagged memory associates metadata with each memory location and can be used to implement
fine-grained memory access restrictions. Attacks which hijack control flow can be prevented by
using this protection to restrict writes to memory locations containing return addresses, function
pointers, and vtable pointers. Importantly, we anticipate this can be implemented with a worst-
case performance overhead of a few percent and a similarly low area cost. This fine-grained
memory protection can be used automatically by the compiler, meaning improved security is
available to existing programs without source code modifications. We intend to provide tagged
memory alongside security features which are already commonly deployed such as secure boot,
encrypted off-chip memory, and cryptographic accelerators."