Rust support for seL4 userspace

This repository contains crates for supporting the use of Rust in seL4 userspace. So far, this includes:

• Rust bindings for the seL4 API (source)
• A runtime for root tasks (source)
• A runtime for seL4 Microkit protection domains (source)
• A CapDL-based system initializer (source and docs)
• A loader for the seL4 kernel (source and docs)
• Custom rustc target specifications for seL4 userspace (JSON and docs)
• Many more crates for use in seL4 userspace

The ./hacking directory contains scripts for developing and testing these crates using Nix and, optionally, Docker.

This work is funded by the seL4 Foundation.

Rendered rustdoc

https://sel4.github.io/rust-sel4/

Compatible versions of related seL4 Foundation projects

This project builds upon seL4 and the seL4 Microkit. In particular, this project works with the following versions of those related projects:

• seL4, when used without Microkit: 1c7a0cb549021bc0781b49aa69359ee8d035981c (github.com/coliasgroup/seL4:rust, an ancestor of github.com/seL4/seL4:master).
• seL4, when used with Microkit: 7b8c552b36fe13b8a846b06a659c23697b7df926 (github.com/coliasgroup/seL4:rust-microkit, not an ancestor of github.com/seL4/seL4:master). For now, Microkit (both upstream trunk and the branch used by this project) requires a patch on top of upstream seL4 trunk.
• seL4 Microkit: 004e340a38d1ed7bf9d1a0223aff8475bba6e6e8 (github.com/coliasgroup/microkit:rust, not an ancestor of github.com/seL4/microkit:main). For now, this project requires a few patches to upstream Microkit trunk which have not yet be upstreamed.

Demos

• Simple root task: https://github.com/seL4/rust-root-task-demo
• Simple system using the seL4 Microkit: https://github.com/seL4/rust-microkit-demo
• HTTP server using the seL4 Microkit: https://github.com/seL4/rust-microkit-http-server-demo

Overview of crates

General crates

• sel4: Straightforward, pure-Rust bindings to the seL4 API.
• sel4-sys: Raw bindings to the seL4 API, generated from the libsel4 headers and interface definition files. This crate is not intended to be used directly by application code, but rather serves as a basis for the sel4 crate's implementation.
• sel4-config: Macros and constants corresponding to the seL4 kernel configuration. Can be used by all targets (i.e. in all of: application code, build scripts, and build-time tools).
• sel4-platform-info: Constants corresponding to the contents of platform_info.h. Can be used by all targets.
• sel4-sync: Synchronization constructs using seL4 IPC. Currently only supports notification-based mutexes.
• sel4-logging: Log implementation for the log crate.
• sel4-externally-shared: Abstractions for interacting with data structures in shared memory.
• sel4-shared-ring-buffer: Implementation of shared data structures used in the seL4 Device Driver Framework.
• sel4-async-*: Crates for leveraging async Rust in seL4 userspace.

Runtime crates

• Root task:
  • sel4-root-task: A runtime for root tasks that supports thread-local storage and unwinding, and provides a global allocator.
• seL4 Microkit:
  • sel4-microkit: A runtime for seL4 Microkit protection domains, including an implementation of libmicrokit and abstractions for IPC.

Programs

• sel4-capdl-initializer: A CapDL-based system initializer.
• sel4-kernel-loader: A loader for the seL4 kernel, similar in purpose to elfloader.

Integrating these crates into your project

The best way to learn how to integrate these crates into your project is to check out these concrete examples of their use listed above.

These crates are not yet hosted on crates.io. Use them either as Git or path Cargo dependencies.

Some of these crates depend, at build time, on external components and configuration. In all cases, information for locating these dependencies is passed to the dependant crates via environment variables which are interpreted by build.rs scripts. Here is a list of environment variables that the crates which use them:

• sel4-config and sel4-sys, whose dependants include sel4, sel4-root-task, sel4-microkit, and many more, use $SEL4_INCLUDE_DIRS (defaulting to $SEL4_PREFIX/libsel4/include if $SEL4_PREFIX is set) which must contain a colon-separated list of include paths for the libsel4 headers. See the the sel4 crate's rustdoc for more information.
• sel4-platform-info, whose dependants include sel4-kernel-loader, uses $SEL4_PLATFORM_INFO (defaulting to $SEL4_PREFIX/support/platform_gen.yaml if $SEL4_PREFIX is set) which must contain the path of the platform_gen.yaml file from the seL4 kernel build system.
• sel4-kernel-loader uses $SEL4_KERNEL (defaulting to $SEL4_PREFIX/bin/kernel.elf if $SEL4_PREFIX is set) which must contain the path of the seL4 kernel (as an ELF executable). Furthermore, if $SEL4_KERNEL_LOADER_CONFIG is set, then sel4-kernel-loader overrides the default configuration with one in the provided JSON file. Note that no configuration options are actually implemented yet.

Quick start for running the tests in this repository

The only requirements for building and running the tests in this repository are Linux, Make, rustup, and Nix. This repository contains scripts for setting up a Docker container with a suitable development environment in case you aren't on Linux or don't want to install Nix.

First, clone this repository:

git clone https://github.com/seL4/rust-sel4
cd rust-sel4

If you are using Docker, build, run, and enter a Docker container for development. This container mounts this repository's top-level at /work.

cd hacking/docker && make run && make exec

At this repository's top-level directory, build and simulate a simple seL4-based system with a root task written in Rust (this will take a few minutes):

make example

Build and run all of this repository's automated tests:

make run-tests