iq-scm / tamago

TamaGo - ARM/RISC-V bare metal Go

TamaGo - bare metal Go for ARM/RISC-V SoCs

tamago | https://github.com/usbarmory/tamago

Copyright (c) WithSecure Corporation
https://foundry.withsecure.com

Introduction

TamaGo is a framework that enables compilation and execution of unencumbered Go applications on bare metal ARM/RISC-V System-on-Chip (SoC) components.

The projects spawns from the desire of reducing the attack surface of embedded systems firmware by removing any runtime dependency on C code and Operating Systems.

The TamaGo framework consists of the following components:

• A modified Go distribution which extends GOOS support to the tamago target, allowing bare metal execution.

• Go packages for SoC driver support.

• Go packages for board support.

The modifications are meant to be minimal for both the Go distribution (< ~4000 LOC changed) and the target application (one import required), with a clean separation from other architectures.

Strong emphasis is placed on code re-use from existing architectures already included within the standard Go runtime, see Internals.

Both aspects are motivated by the desire of providing a framework that allows secure Go firmware development on embedded systems.

Current release level

The current release for the TamaGo modified Go distribution is tamago1.20.4, which adds GOOS=tamago support to go1.20.4.

Binary releases for amd64 and armv7l Linux hosts are available.

Documentation

The main documentation can be found on the project wiki.

The package API documentation can be found on pkg.go.dev.

Supported ARM hardware

The following table summarizes currently supported ARM SoCs and boards (GOOS=tamago GOARCH=arm).

SoC	Board	SoC package	Board package
NXP i.MX6ULZ	USB armory Mk II	imx6ul	usbarmory/mk2
NXP i.MX6ULL	MCIMX6ULL-EVK	imx6ul	mx6ullevk
BCM2835	Raspberry Pi Zero	bcm2835	pi/pizero
BCM2835	Raspberry Pi 1 Model A+	bcm2835	pi/pi1
BCM2835	Raspberry Pi 1 Model B+	bcm2835	pi/pi1
BCM2836	Raspberry Pi 2 Model B	bcm2835	pi/pi2

Supported RISC-V hardware

The following table summarizes currently supported RISC-V SoCs and boards (GOOS=tamago GOARCH=riscv64).

SoC	Board	SoC package	Board package
SiFive FU540	QEMU sifive_u	fu540	qemu/sifive_u

Compiling

Go applications are simply required to import, the relevant board package to ensure that hardware initialization and runtime support takes place:

import (
	// Example for USB armory Mk II
	_ "github.com/usbarmory/tamago/board/usbarmory/mk2"
)

Build the TamaGo compiler (or use the latest binary release):

wget https://github.com/usbarmory/tamago-go/archive/refs/tags/latest.zip
unzip latest.zip
cd tamago-go-latest/src && ./all.bash
cd ../bin && export TAMAGO=`pwd`/go

Go applications can be compiled with the compiler built in the previous step, with the addition of a few flags/variables:

# Example for USB armory Mk II
GO_EXTLINK_ENABLED=0 CGO_ENABLED=0 GOOS=tamago GOARM=7 GOARCH=arm \
  ${TAMAGO} build -ldflags "-T 0x80010000 -E _rt0_arm_tamago -R 0x1000"

# Example for QEMU RISC-V sifive_u
GO_EXTLINK_ENABLED=0 CGO_ENABLED=0 GOOS=tamago GOARCH=riscv64 \
  ${TAMAGO} build -ldflags "-T 0x80010000 -E _rt0_riscv64_tamago -R 0x1000"

See the respective board package README file for compilation information for each specific target.

Executing and debugging

See the respective board package README file for execution and debugging information for each specific target (real or emulated).

The example application provides sample driver usage and instructions for native as well as emulated execution.

An emulated run of the example application can be launched as follows:

git clone https://github.com/usbarmory/tamago-example
cd tamago-example && make qemu

Applications using TamaGo

• GoKey - the bare metal Go smartcard
• GoTEE - Go Trusted Execution Environment
• armory-drive - USB encrypted drive
• armory-ums - USB Mass Storage firmware
• armory-boot - primary bootloader
• tamago-example - TamaGo example application

External drivers using TamaGo

• imx-usbserial - i.MX Serial over USB driver
• imx-usbnet - i.MX Ethernet over USB driver
• imx-enet - i.MX Ethernet driver

Additional resources

• Package API
• Internals
• Go stdlib support
• FAQ
• TamaGo presentation

Maintainers

Andrea Barisani
[email protected] | [email protected]

Andrej Rosano
[email protected] | [email protected]

License

tamago | https://github.com/usbarmory/tamago
Copyright (c) WithSecure Corporation

This project is distributed under the BSD-style license found in the LICENSE file.

The TamaGo logo is adapted from the Go gopher designed by Renee French and licensed under the Creative Commons 3.0 Attributions license. Go Gopher vector illustration by Hugo Arganda.