ProcessorFuzz

Tool

ProcessorFuzz is a processor fuzzing tool that guides input generation with a CSR-transition coverage metric. It monitors transitions in Control and Status Registers (CSRs), treating CSR changes as signals that execution has reached new processor states. The tool is described as HDL-agnostic and requiring no instrumentation in the processor design. It was evaluated on the Rocket, BOOM, and BlackParrot open-source RISC-V processors, where it triggered ground-truth bugs 1.23× faster on average than DIFUZZRTL and exposed eight new RISC-V core bugs plus one reference-model bug.

First seen 5/28/2026

Last seen 9/10/2026

Evidence 97 chunks

Wiki v5

WIKI

Overview

ProcessorFuzz is a processor fuzzer introduced to improve RTL processor verification using fuzzing feedback based on processor Control and Status Registers (CSRs). The paper listing for “ProcessorFuzz: Processor Fuzzing with Control and Status Registers Guidance” names Sadullah Canakci, Chathura Rajapaksha, Leila Delshadtehrani, Anoop Mysore Nataraja, Michael Bedford Taylor, Manuel Egele, and Ajay Joshi as authors, and lists the work in IEEE HOST 2023, pages 1–12. [publication]

The work is motivated by the increasing difficulty of finding processor bugs before manufacturing. Its abstract notes that undiscovered microarchitectural bugs can become security vulnerabilities, side channels, or functional bugs, and that earlier RTL hardware-fuzzing approaches can suffer from limited HDL support and misleading coverage signals. [motivation]

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NEIGHBORHOOD

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RELATIONSHIPS

50 connections

DiFuzzRTL ← compares with 100% 18e

ProcessorFuzz is compared against DIFUZZRTL, showing it triggers bugs 1.23x faster on average.

Control and Status Registers uses → 100% 12e

ProcessorFuzz monitors transitions in Control and Status Registers to guide the fuzzer.

ISA Simulation uses → 100% 9e

ProcessorFuzz uses an ISA simulator to collect CSR transition coverage.

Spike ISA simulator uses → 100% 9e

ProcessorFuzz uses the Spike ISA simulator to capture CSR transitions.

differential testing implements → 97% 7e

ProcessorFuzz uses differential testing with ISA simulation as a reference.

mutation engine uses → 100% 7e

ProcessorFuzz employs a mutation engine to generate new test inputs.

Coverage-based Greybox Fuzzing implements → 95% 6e

ProcessorFuzz implements coverage-based greybox fuzzing adapted for hardware processors.

CSR-transition coverage uses → 100% 5e

ProcessorFuzz uses CSR-Transition Coverage as its novel coverage metric to guide fuzzing.

RTL Simulation uses → 100% 5e

ProcessorFuzz runs RTL simulation to collect extended trace logs for comparison.

extended ISA trace log uses → 100% 4e

ProcessorFuzz generates and processes extended ISA trace logs containing CSR values.

Processor Fuzzing implements → 100% 4e

ProcessorFuzz is a processor fuzzing tool.

CSR-transition coverage implements → 100% 4e

ProcessorFuzz implements the CSR-transition coverage metric to guide fuzzing.

ProcessorFuzz paper ← introduces 100% 4e

The ProcessorFuzz paper introduces the ProcessorFuzz tool.

ISA simulation uses → 100% 4e

ProcessorFuzz uses ISA simulation to rapidly evaluate test inputs for coverage.

Verilator uses → 100% 4e

ProcessorFuzz uses Verilator for RTL simulation of processor designs.

ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers ← introduces 100% 4e

The work presents ProcessorFuzz as a new processor fuzzing tool.

Transition Unit uses → 100% 4e

ProcessorFuzz employs a Transition Unit to extract and evaluate CSR transitions.

BOOM evaluates → 100% 4e

ProcessorFuzz was evaluated on the BOOM open-source RISC-V processor.

Dromajo uses → 100% 4e

ProcessorFuzz uses Dromajo as a reference model for BlackParrot core verification.

Differential Testing implements → 100% 3e

ProcessorFuzz uses differential testing by comparing RTL and ISA simulation outputs.

Coverage-based Greybox Fuzzing implements → 95% 3e

ProcessorFuzz uses coverage-guided fuzzing with CSR-transition coverage metric

BlackParrot evaluates → 100% 3e

ProcessorFuzz was evaluated on the BlackParrot open-source RISC-V processor.

seed corpus uses → 100% 3e

ProcessorFuzz starts with a seed corpus of test programs.

Physical Memory Protection mentions → 85% 3e

ProcessorFuzz discovered a bug in Dromajo related to Physical Memory Protection checks.

Rocket Core evaluates → 100% 3e

ProcessorFuzz was evaluated on the Rocket open-source RISC-V processor.

Transition Map uses → 100% 3e

ProcessorFuzz uses the Transition Map to store and check CSR transitions.

hardware fuzzing implements → 100% 3e

ProcessorFuzz is a hardware fuzzer that implements hardware fuzzing for processor verification.

ProcessorFuzz: Processor Fuzzing with Control and Status Registers Guidance ← introduces 100% 3e

The paper presents the ProcessorFuzz tool for processor fuzzing guided by control and status registers.

CSR-transition coverage implements → 100% 2e

ProcessorFuzz implements the CSR-transition coverage metric as its core feedback mechanism.

assembly program test input uses → 100% 2e

ProcessorFuzz uses assembly programs as test inputs for fuzzing.

Control and Status Register uses → 100% 2e

ProcessorFuzz uses Control and Status Register transitions to guide fuzzing.

pre-silicon verification uses → 95% 2e

ProcessorFuzz targets pre-silicon verification of processor designs.

Seed Scheduling uses → 85% 2e

ProcessorFuzz uses coverage feedback to guide seed scheduling

RISC-V uses → 95% 2e

ProcessorFuzz is evaluated on RISC-V processor implementations

BlackParrot Core evaluates → 100% 2e

ProcessorFuzz was evaluated on the BlackParrot Core processor.

Hardware fuzzing uses → 100% 2e

ProcessorFuzz is a hardware fuzzing tool for processor RTL verification.

RFUZZ compares with → 85% 2e

RFuzz is cited as related hardware fuzzing research.

RTL simulation uses → 100% 2e

ProcessorFuzz launches RTL simulation for inputs that pass the ISA simulation filter.

privilege mode mentions → 90% 2e

ProcessorFuzz tracks privilege mode transitions as part of CSR-transition coverage.

golden model uses → 90% 2e

ProcessorFuzz relies on a golden model (ISA simulator) to detect bugs via trace comparison.

Differential Testing uses → 90% 2e

ProcessorFuzz uses differential testing by comparing ISA and RTL simulation traces

fflags CSR mentions → 100% 2e

ProcessorFuzz monitors fflags CSR transitions for floating-point state tracking.

Processor Fuzzing implements → 98% 2e

ProcessorFuzz is specifically tailored for fuzzing processors

Time-to-Exposure uses → 95% 2e

Time-to-Exposure is used as a metric to evaluate ProcessorFuzz

Rocket Core evaluates → 100% 2e

ProcessorFuzz was evaluated on the Rocket Core processor.

Sadullah Canakci authored by → 100% 2e

ProcessorFuzz is proposed by Sadullah Canakci as part of his dissertation

mstatus CSR mentions → 100% 2e

ProcessorFuzz monitors mstatus CSR transitions as part of its coverage metric.

Fine-Grained Code Analysis for Processor Fuzzing ← compares with 98% 2e

The paper compares its results against ProcessorFuzz in branch coverage and bug discovery.

Floating-Point Unit Verification evaluates → 90% 2e

ProcessorFuzz can be configured to focus on floating-point unit verification.

RISC-V ISA uses → 95% 2e

ProcessorFuzz targets RISC-V based processors designed in different HDLs.

LINKED ENTITIES

5 links

ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers INTRODUCES Extracted graph relationship

CSR-transition coverage metric USES Extracted graph relationship

CSRs USES Extracted graph relationship

Processor Fuzzing IMPLEMENTS Extracted graph relationship

DiFuzzRTL COMPARES_WITH Extracted graph relationship

CITATIONS

8 sources

8 citations — click to expand

[1] publication ProcessorFuzz: Processor Fuzzing with Control and Status Registers Guidance - researchr publication

[2] motivation ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI

[3] csr-transition ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI

[4] hdl-agnostic ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI

[5] evaluation-targets ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI

[6] difuzzrtl-comparison ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI

[7] bug-results ProcessorFuzz: Guiding Processor Fuzzing using Control and Status Registers | DeepAI

[8] later-context FuSS: Coverage-Directed Hardware Fuzzing with Selective Symbolic Execution