A few months ago I was reading this article about coroutines in game development and how they are great tools for writing scripts (as in movie scripts) in the same language as the game engine. Until then I heard about coroutines but never really gave them a thought, this piqued my curiosity.
A new online Learn course has been published offering an Introduction To Embedded Systems Programming.
Every year since 2015, a team of dedicated individuals led by Eric Wastl organizes an online programming challenge called: Advent of Code. The concept is simple yet brilliant: from December 1st to 25th, every day a new small programming exercise is published on the adventofcode.com website. This year we want to join the fun, and bring a little bit of extra motivation for a good cause.
Today I want to share a great story about why many NVIDIA products are now running formally verified SPARK code. This blog post is in part a teaser for the case study that NVIDIA and AdaCore published today. Our journey begins with the NVIDIA Security Team. Like many other security oriented teams in our industry today, they were looking for a measurable answer to the increasingly hostile cybersecurity environment and started questioning their software development and verification strategies.
Writing secure software in C is hard. It takes just one missed edge case to lead to a serious security vulnerability, and finding such edge cases is difficult. This blog post discusses a recent vulnerability in a popular SHA-3 library and how the same problems were avoided in my own SHA-3 library written in SPARK.
While implementing application logic in Ada or SPARK is an improvement over a pure C project, its weakest link is still the C code in the SDK. On the other hand, there are many libraries, board support packages, and SDKs written in Rust, easily usable with Cargo. So instead of building the Ada application on top of a C base, one could use a Rust base instead to combine the large catalog of ready-to-use software with Rust's safety features, providing a much more solid base for an Ada project.
Security is only as strong as its strongest link. That's important to keep in mind for software security, with its long chain of links, from design to development to deployment. Last year, members of NVIDIA's Offensive Security Research team (aka "red team") presented at DEF CON 29 their results on the evaluation of the security of a firmware written in SPARK and running on RISC-V. The ended up not finding vulnerabilities in the code, but in the RISC-V ISA instead. This year, the same team presented at DEF CON 30 a retrospective on the security evaluation of 17 high-impact projects since 2020. TL;DR: using SPARK makes a big difference for security, compared to using C/C++.
We have added several new convenience features that help work with comments and string literals in Ada code.
Fuzzing Out Bugs in Safety-Critical Embedded Software: Paul Butcher from AdaCore talks to Brandon Lewis from Embedded Toolbox
For years in this blog my colleagues and I have published examples, demos, and how-to’s on Ada/SPARK embedded (as in bare-metal) development. Most of the time, if not always, we focused on one way of doing things: to start from scratch and write everything in Ada/SPARK, from the low level drivers to the application. While this way of doing Ada/SPARK embedded will yield the best results in terms of software quality, it might not be the most efficient in all cases. In this blog post I want to present an alternative method to introduce Ada/SPARK into your embedded development projects.
After two years of virtual events, we are very happy to report that the High Integrity Software Conference (HIS) will be making a physical comeback on Tuesday 11th October 2022 at the Bristol Marriott Hotel City Centre, Bristol, UK. Since 2014, AdaCore has been co-organising the event with Capgemini Engineering (previously known as Altran Technologies, SA). The success and growth of the conference have ensured it remains a regular fixture for returning delegates, and the exciting lineup for this year's event will ensure HIS 2022 is no exception!
We are pleased to announce the publication of the initial draft of the Ferrocene Language Specification (FLS) - a qualification-oriented document that details the Rust language as it specifically relates to Ferrocene.
We're happy to announce our the second edition of our programming competition, the Ada/SPARK Crate Of The Year Award! We believe the Alire package manager is a game changer for Ada/SPARK, so we want to use this competition to reward the people contributing to the ecosystem.
When an enthusiastic Ada programmer and a SPARK expert pair up to prove the most "stupid" sorting algorithm, lessons are learned! Join us in this eye-opening journey.
Today we have two exciting announcements for the future of the Ada/SPARK ecosystem.
A retrospective on learning Ada and developing a tool with it in 2021 from 2021 Ada Crate of the Year Winner Paul Jarrett.
As I explained in a blog post a couple of years ago, pointers are subjected to a strict ownership policy in SPARK. It prevents aliasing and allows for an efficient formal verification model. Of course, it comes at the cost of restrictions which might not be applicable to all usage. In particular, while ownership makes it possible to represent certain recursive data-structures, those involving cycles or sharing are de-facto forbidden. This is a choice, and not every proof tool did the same. For example, the WP plug-in of Frama-C supports pointers with arbitrary aliasing. If some information about the separation of memory cells is necessary to verify a program, then the user shall give the annotation explicitly. I have investigated modeling pointers with aliasing in SPARK as indices in a big memory array. I will present the results of my experiments in this blog post. We will see that, while such a representation is indeed possible modulo some hiding in SPARK, it can quickly become rather heavy in practice.
A few weeks ago a piece of code went viral in the online dev community. The “Quite OK Image Format” (QOI) is a fast, lossless image compression designed to have a very simple implementation (about 300 lines of C). Shortly, a few alternative implementations popped up here and there, and in this kind of situation we are eager to show what Ada/SPARK can bring to the table.
In this second post of the Ada GameDev series we will see how to create game maps and export them to a format that is compatible with the GESTE library.
Manuel Hatzl is the winner of the 2021 SPARK Crate of the year! In this blog post he shares his experience using Ada/SPARK and how he created the spark_unbound library
In this first entry of the series, I want to present my GEneric Sprite and Tile Engine (GESTE) project. The goal of GESTE is to bring the rendering and anesthetic of 8bit era game consoles to modern microcontrollers.
The GNAT light runtime library is a version of the runtime library targeted at embedded platforms and certification, which has been certified for use at the highest levels of criticality in several industrial domains. It contains around 180 units focused mostly on I/O, numerics, text manipulation, memory operations. We have used SPARK to prove the correctness of 40 of them: that the code is free of runtime errors, and that it satisfies its functional specifications.
For over 25 years, AdaCore has been committed to supporting the needs of safety- and mission-critical industries. This started with an emphasis on the Ada programming language and its toolchain, and over the years has been extended to many other technologies. AdaCore’s product offerings today include support for the Ada language and its formally verifiable SPARK subset, C and C++, and Simulink and Stateflow models. We have accomplished this while addressing the requirements of various safety standards such as DO-178B/C, EN 50128, ECSS-E-ST-40C / ECSS-Q-ST-80C, IEC 61508 and ISO 26262.
Like previous years, AdaCore will participate in FOSDEM. Once again the event will be online only, but this won’t prevent us from celebrating Open Source software and it is an opportunity for even more people to participate around the world.
In June of 2021 we announced the launch of a new programming competition called Ada/SPARK Crate Of The Year Awards. We believe the Alire source package manager is a game changer for Ada/SPARK, so we want to use this competition to reward the people contributing to the ecosystem. Today we are pleased to announce the results. But first, we want to congratulate all the participants, and the Alire community at large, for reaching 200 crates in the ecosystem in January of this year. We truly believe in a bright future for the Ada/SPARK open-source ecosystem with Alire at the forefront. Reaching this milestone is a great sign, inside and outside the Ada/SPARK community, of the evolution and the energy of the ecosystem.
SPARKNaCl is a SPARK version of the TweetNaCl cryptographic library, developed by formal methods and security expert Rod Chapman. For two years now, Rod has been developing and optimizing this open-source cryptographic library while preserving the automatic type-safety proof across code changes and tool updates. He has recently given a talk about this experience that I highly recommend.
Through the HICLASS UK research group, AdaCore has been developing security-focused software development tools that are aligned with the objectives stated within the avionics security standards. In addition, they have been developing further guidelines that describe how vulnerability identification and security assurance activities can be described within a Plan for Security Aspects of Certification.
A couple years ago I started to tackle what was probably my most daunting project at the time, an embedded USB Device stack written 100% in Ada.
A few days ago, someone asked on the Ada Drivers Library repository how to add support for the SAMD21 micro-controller. Nowadays, I would rather recommend people to contribute this kind of micro-controller support project to the Alire ecosystem. I started to write a few instructions on how to get started, but it quickly became a blog-worthy piece of text.
The developers of CycloneTCP library at Oryx Embedded partnered with AdaCore to replace the TCP part of the C codebase by SPARK code, and used the SPARK tools to prove both that the code is not vulnerable to the usual runtime errors (like buffer overflow) and that it correctly implements the TCP automaton specified in RFC 793. As part of this work, we found two subtle bugs related to memory management and concurrency. This work has been accepted for publication at the upcoming IEEE SecDev 2021 conference.
This blog entry shows how to define an abstract data type that allows tasks to block on objects of the type, waiting for resumption signals from other components, for at most a specified amount of time per object. This "timeout" capability has been available in Ada from the beginning, via select statements containing timed entry calls. But what about developers working within the Ravenscar and Jorvik tasking subsets? Select statements and timed calls are not included within either profile. This new abstraction will provide some of the functionality of timed entry calls, with an implementation consistent with the Ravenscar and Jorvik subsets.
When I do Object Oriented Programming with Ada, I tend to follow a design pattern that makes it easier for me and hopefully also for people reading my code.
NVIDIA has been using SPARK for some time now to develop safety- and security-critical firmware applications. At the recent DEF CON 29, hackers Zabrocki and Matrosov presented how they went about attacking NVIDIA firmware written in SPARK but ended up attacking the RISC-V ISA instead!Zabrocki starts by explaining the context for their red teaming exercise at NVIDIA, followed by a description of SPARK and their evaluation of the language from a security attack perspective. He shows how they used an extension of Ghidra to decompile the binary code generated by GNAT and describes the vulnerability they identified in the RISC-V ISA thanks to that decompilation. Matrosov goes on to explain how they glitched the NVIDIA chip to exploit this vulnerability. Finally, Zabrocki talks about projects used to harden RISC-V platforms.
Part of AdaCore's ongoing efforts under the HICLASS project is to demonstrate how the SPARK technology can play an integral part in the security-hardening of existing software libraries written in other non-security-oriented programming languages such as C. This blog post presents the first white paper under this work-stream, “Security-Hardening Software Libraries with Ada and SPARK”.
We're happy to announce our new programming competition, the Ada/SPARK Crate Of The Year Award! We believe the Alire package manager is a game changer for Ada/SPARK, so we want to use this competition to reward the people contributing to the ecosystem.
This post continues our adventures with SPARKNaCl - our verified SPARK version of the TweetNaCl cryptographic library. This time, we'll be looking at yet more performance improvement via proof-driven "operator narrowing", porting the library to GNAT Community 2021, and the effect that has on proof and performance of the code.
Women make up roughly 38% of the global workforce, yet they constitute only 10–20% of the engineering workforce. In the U.S., numbers suggest that 40% of women who graduate with engineering degrees never enter the profession or eventually leave it. Why? The reasons vary but primarily involve socio-economic constraints on women in general, workplace inequities, and lack of support for work-life balance. Sadly, history itself has often failed to properly acknowledge the instrumental contributions of women inventors, scientists, and mathematicians who have helped solve some of our world's toughest challenges. How can young women emulate their successes if they don't even know about them?
As we've seen previously in Ada 2022 support in GNAT, the support for Ada 2022 is now mostly there for everyone to take advantage of. We're now crossing fingers for this new revision to be officially stamped by ISO in 2022.
We are happy to announce that the GNAT Community 2021 release is now available via https://www.adacore.com/download. Here are some release highlights:
The Ada 2022 draft defines a new tasking profile named Jorvik (pronounced “Yourvick”), based directly on the standard Ravenscar profile. Jorvik relaxes certain restrictions in order to increase expressive power for real-time/embedded Ada and SPARK applications. We will explore the details in this blog entry.
I am following the evolution of the embedded Rust community and in particular the work of James Munns from Ferrous-Systems. One of the projects that caught my attention is bbqueue, a single producer, single consumer, lockless, thread safe queue, based on BipBuffers.
Ada has a concurrency construct known as “entry families” that, in some cases, is just what we need to express a concise, clear solution.
In the integrated development environment, GNAT Studio, there is now a plugin that inserts the generated Global contracts inline with the code.
Following my last blog entry, further experiments show how the performance of SPARKNaCl can be doubled (again), plus analysis of worst-case stack usage and code size at all optimization levels.
This blog goes into the details of both measuring and improving the runtime performance of SPARKNaCl on a real "bare metal" embedded target, and comparing results with those for the original "TweetNaCl" C implementation.
Like previous years, AdaCore will participate in FOSDEM. This time the event will be online only, but this won’t prevent us from celebrating Open Source software. AdaCore engineers will give two talks in the Safety and Open Source devroom, a topic at the heart of AdaCore since its inception.
Beyond the great look, the Mini SAM M4 provide a powerful 120 Mhz Microchip SAMD51 Cortex-M microcontroller, a couple of LEDs and a user button. Let's program it with Ada.
Using GNAT Pro with containerization technologies, such as Docker, is so easy, a whale could do it!
In this blog post I want to present a new tool that allows one to very quickly and easily start Ada programming on any ARM Cortex-M or RISC-V microcontroller.