This is a "hello world" project to play with Rust inline assembly. Inline assembly was introduced with Rust 1.59 release (2022-02-24) and this is an attempt to learn more about it.

Inspiration from this little project also comes from @iMilnb and the C From Scratch video series, mainly this show https://www.youtube.com/watch?v=F-Ow6-uH6Mc

The goal of the project is to show:

• How to call the write and uname syscall directly using assembly.
• How to use raw pointers and a bit of FFI (Foreign Fonction Interface) to share data.
• Usage of unsafe in such cases.
• Implementation of the From trait to convert data from the C style structure to the Rust one. This part is shamefully more or less copied from the uname crate.

The asm directory contains a "hello world" example written in assembly and was used as a reference for the project.

The project uses x86_64 assembly and is targeting a Linux x86_64 operating system. It means that it will not be able to run on another platform or CPU.

Of course, tracing the program with stace shows the syscalls explicitly requested with inline assembly :

execve("./target/debug/asm", ["./target/debug/asm"], 0x7fff86007bb0 /* 90 vars */) = 0
...
...
write(1, "Hello from: ", 12Hello from: )            = 12
write(1, "\360\237\246\211 Uggla !!!\n", 15🦉 Uggla !!!
) = 15
uname({sysname="Linux", nodename="ugglalaptop", ...}) = 0
...
...
exit_group(0)                           = ?
+++ exited with 0 +++

1. Clone the project

  git clone https://github.com/uggla/asm.git

2. Go to the project directory

  cd asm

3. Build and run the program

cargo build
./target/debug/asm

4. Build hello.asm within asm directory (optional)
   Install make, gcc and nasm on your system using your system package manager. Then execute :

cd asm
make
./hello

 uggla   main  ~  workspace  rust  asm  ./target/debug/asm
Hello from: 🦉 Uggla !!!
UnameInfo {
    sysname: "Linux",
    nodename: "ugglalaptop",
    release: "5.16.18-200.fc35.x86_64",
    version: "#1 SMP PREEMPT Mon Mar 28 14:10:07 UTC 2022",
    machine: "x86_64",
    domainname: "(none)",
}