failure linking module `perf_event` template in bpf-linker

[yskelg]

Following the README guide, you need to install bpf-linker on the aarch64 environment as follows.

Right, I've been tested aya-rs on my Apple M2 VMware Fusion Eenvironment with Fedora 40.

$ uname -a
Linux fedora 6.11.0-0.rc1.20240729gitdc1c8034e31b.16.fc41.aarch64+debug #1 SMP PREEMPT_DYNAMIC Tue Jul 30 05:03:16 KST 2024 aarch64 GNU/Linux

I have confirmed that this works well with the XDP template.

If your target is aarch64-unknown-linux-gnu (i.e. Linux on Apple Silicon) you will have to use the external LLVM method.

So, I build with external LLVM method option.

$ cargo install bpf-linker --no-default-features

But, there seems to be error: failure linking module /home/paran/perf-aya-rs/perf-aya-rs-ebpf/../target/bpfel-unknown-none/debug/deps/perf_aya_rs-58caae9717f08677.perf_aya_rs.4b0d608d0cf878c2-cgu.0.rcgu.o

This is my log when linking failed.

$ cargo generate https://github.com/aya-rs/aya-template
⚠️   Favorite `https://github.com/aya-rs/aya-template` not found in config, using it as a git repository: https://github.com/aya-rs/aya-template
🤷   Project Name: perf-aya-rs
🔧   Destination: /home/paran/perf-aya-rs ...
🔧   project-name: perf-aya-rs ...
🔧   Generating template ...
✔ 🤷   Which type of eBPF program? · perf_event
🔧   Moving generated files into: `/home/paran/perf-aya-rs`...
🔧   Initializing a fresh Git repository
✨   Done! New project created /home/paran/perf-aya-rs

$ cd perf-aya-rs/
$ cargo xtask build-ebpf
   ...
   Compiling xtask v0.1.0 (/home/paran/perf-aya-rs/xtask)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 45.50s
     Running `target/debug/xtask build-ebpf`
   ...
   Compiling core v0.0.0 (/home/paran/.rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/core)
   ...
   Compiling rustc-std-workspace-core v1.99.0 (/home/paran/.rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/rustlib/src/rust/library/rustc-std-workspace-core)
   ...
   Compiling perf-aya-rs-common v0.1.0 (/home/paran/perf-aya-rs/perf-aya-rs-common)
   Compiling aya-log-ebpf v0.1.0
   Compiling perf-aya-rs-ebpf v0.1.0 (/home/paran/perf-aya-rs/perf-aya-rs-ebpf)
error: linking with `bpf-linker` failed: exit status: 2
  |
  = note: LC_ALL="C" PATH="/home/paran/.rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/rustlib/aarch64-unknown-linux-gnu/bin:/home/paran/.rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/rustlib/aarch64-unknown-linux-gnu/bin:/home/paran/.rustup/toolchains/nightly-aarch64-unknown-linux-gnu/lib/rustlib/aarch64-unknown-linux-gnu/bin:/home/paran/.cargo/bin:/home/paran/.local/bin:/home/paran/bin:/usr/lib64/ccache:/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin:/home/paran/bin:/home/paran/usr/bin:/home/paran/bin:/home/paran/usr/bin" VSLANG="1033" "bpf-linker" "--export-symbols" "/tmp/rustcW2rljA/symbols" "/tmp/rustcW2rljA/symbols.o" "/home/paran/perf-aya-rs/perf-aya-rs-ebpf/../target/bpfel-unknown-none/debug/deps/perf_aya_rs-58caae9717f08677.perf_aya_rs.4b0d608d0cf878c2-cgu.0.rcgu.o" "--cpu" "generic" "-o" "/home/paran/perf-aya-rs/perf-aya-rs-ebpf/../target/bpfel-unknown-none/debug/deps/perf_aya_rs-58caae9717f08677" "-O3" "--debug"
  = note: error: failure linking module /home/paran/perf-aya-rs/perf-aya-rs-ebpf/../target/bpfel-unknown-none/debug/deps/perf_aya_rs-58caae9717f08677.perf_aya_rs.4b0d608d0cf878c2-cgu.0.rcgu.o

error: could not compile `perf-aya-rs-ebpf` (bin "perf-aya-rs") due to 1 previous error
thread 'main' panicked at xtask/src/build_ebpf.rs:65:5:
assertion failed: status.success()
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

Do you know anyone who could help with this, or could you provide some hints for debugging it myself?

I think it would be great if I could looking into it and contribute to this issue.

[OmriSteiner]

I ran into this earlier. I believe this is due to Rust nightly upgrading to LLVM 19 and bpf-linker using LLVM 18.

214 was merged and a new version of bpf-linker is available, so that should probably solve it.

Either that or roll back to rust nightly 2024-07-31 (or earlier).