With -Z emit-stack-sizes we can get the stack sizes of each function in the final firmware. This could be used to analyze stack usage to fix stack-overflows. This could be made into a small util. Currently this issue will be used to document the (hacky) process:

Steps:

1. use nightly
2. add to the linker script SECTIONS (need to be added to runners/embedded/ld/cortex-m-rt_0.6.15_link.x):

  /* `INFO` makes the section not allocatable so it won't be loaded into memory */
  .stack_sizes (INFO) :
  {
    KEEP(*(.stack_sizes));
  }

3. add strip = false to release profile
4. compile with RUSTFLAGS="-Z emit-stack-sizes" make flash-develop EXTRA_FEATURES=... (from utils/nrf-builder)
5. use the following script to get the functions (path may need to be adjusted):

#!/usr/bin/env cargo

//! ```cargo
//! [package]
//! edition = "2021"
//! [dependencies]
//! stack-sizes = "0.5.0"
//! ```

use std::fs::read;

use stack_sizes::analyze_executable;
fn main() {
    let path = "../nitrokey-3-firmware/target/thumbv7em-none-eabihf/release/nrf52_runner";
    let data = read(path).unwrap();
    let functions = analyze_executable(&data).unwrap();
    let mut sorted: Vec<_> = functions.defined.into_values().collect();
    sorted.sort_by_key(|f| f.stack().unwrap_or(0));
    println!("{sorted:#?}");
}