  The Internet of Things (IoT) is an ongoing technological revolution. Embedded
processors are the processing engines of smart IoT devices. For decades, these
processors were mainly based on the Arm instruction set architecture (ISA). In
recent years, the free and open RISC-V ISA standard has attracted the attention
of industry and academia and is becoming the mainstream. Data security and user
privacy protection are common challenges faced by all IoT devices. In order to
deal with foreseeable security threats, the RISC-V community is studying
security solutions aimed at achieving a root of trust (RoT) and ensuring that
sensitive information on RISC-V devices is not tampered with or leaked. Many
RISC-V security research projects are underway, but the academic community has
not yet conducted a comprehensive survey of RISC-V security solutions. In order
to fill this research gap, this paper presents an in-depth survey on RISC-V
security technologies. This paper summarizes the representative security
mechanisms of RISC-V hardware and architecture. Based on our survey, we predict
the future research and development directions of RISC-V security. We hope that
our research can inspire RISC-V researchers and developers.
