Project Description
Rust language is on the way to enter linux kernel, use this hackweek to explore and learn what this could bring us (or not).
Goal for this Hackweek
No fixed goals, learn as much as possible, but some topics for inspiration:
- set up compilation and testing environment
- try to understand some aspects of the implementation
- locking primitives
- unsafe memory operations
- passing C <-> rust data structures
- higher level aspects
- limitations of current implementation, eg. can other subsystems be adapted for rust
- differences when designing interconnected data structures C vs rust
- example drivers and code
- analyze existing example driver
- try to write own
- analyze generated assembly object code
Resources
- https://doc.rust-lang.org/book/ rust language documentation
- v7 https://lore.kernel.org/lkml/20220523020209.11810-1-ojeda@kernel.org/
- https://github.com/Rust-for-Linux/linux.git -- linux sources with rust patches
- rust kernel API https://rust-for-linux.github.io/docs/kernel/
- TBD slack/IRC channel for discussions
- TBD lwn.net articles about the progress
Skill level:
- rust coding - beginner to expert
- rust enthusiasm - skeptic to fanatic
- linux kernel - intermediate to expert
Howtos
Rust
You can use rustup
tool to install the versions manually (package available in openSUSE), we require 1.61
, this is also available in openSUSE.
```
rustup toolchain install 1.61
rustup default 1.61
rustup toolchain list
stable-x8664-unknown-linux-gnu nightly-x8664-unknown-linux-gnu 1.61-x86_64-unknown-linux-gnu (default) ```
The linux+rust support
- must read -- https://github.com/Rust-for-Linux/linux/blob/rust/Documentation/rust/quick-start.rst
- use this -- development repository (https://github.com/Rust-for-Linux/linux.git)
- do not use -- linux-next (https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git) -- rust patchset is there but compilation does not work with 1.60,
Linux
Checkout the Rust-for-Linux git tree, all make
commands need to be run as make LLVM=1
so the llvm support is detected even for configuration phase
make LLVM=1 defconfig
scripts/enable CONFIG_RUST
andmake LLVM=1 oldconfig
make LLVM=1 menuconfig
, navigate to General to enable rust and to Kernel hacking to enable all examplesmake LLVM=1 -j 16
to start build
Drivers, config options:
- ANDROIDBINDERIPC_RUST
- GPIOPL061RUST
- SAMPLES_RUST -- check all
- RUST_* namespace, various safety and debugging options
This project is part of:
Hack Week 21
Activity
Comments
Be the first to comment!
Similar Projects
early stage kdump support by mbrugger
Project Description
When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.
Goal for the Hackweeks
- Investigate if this is possible and the implications it would have (done in HW21)
- Hack up a PoC (done in HW22 and HW23)
- Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).
update HW23
- I was able to include the crash kernel into the kernel Image.
- I'll need to find a way to load that from
init/main.c:start_kernel()
probably afterkcsan_init()
- I workaround for a smoke test was to hack
kexec_file_load()
systemcall which has two problems:- My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
- As the crash kernel is part of init.data it will be already stale once I can call
kexec_file_load()
from user-space.
The solution is probably to rewrite the POC so that the invocation can be done from init.text (that's my theory) but I'm not sure if I can reuse the kexec infrastructure in the kernel from there, which I rely on heavily.
update HW24
- Day1
- rebased on v6.12 with no problems others then me breaking the config
- setting up a new compilation and qemu/virtme env
- getting desperate as nothing works that used to work
- Day 2
- getting to call the invocation of loading the early kernel from
__init
afterkcsan_init()
- getting to call the invocation of loading the early kernel from
Day 3
- fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
- code refactoring
- I'm now able to load the crash kernel
- When using virtme I can boot into the crash kernel, also it doesn't boot completely (major milestone!), crash in
elfcorehdr_read_notes()
Day 4
- crash systems crashes (no pun intended) in
copy_old_mempage()
link; will need to understand elfcorehdr... - call path
vmcore_init() -> parse_crash_elf_headers() -> elfcorehdr_read() -> read_from_oldmem() -> copy_oldmem_page() -> copy_to_iter()
- crash systems crashes (no pun intended) in
Day 5
- hacking
arch/arm64/kernel/crash_dump.c:copy_old_mempage()
to see if crash system really starts. It does. - fun fact: retested with more reserved memory and with UEFI FW, host kernel crashes in init but directly starts the crash kernel, so it works (somehow) \o/
- hacking
TODOs
- fix elfcorehdr so that we actually can make use of all this...
- test where in the boot
__init()
chain we can/should callkexec_early_dump()