A README.md explaining how to run bpftool tests. Signed-off-by: Manu Bretelle <chantr4@xxxxxxxxx> --- .../selftests/bpf/bpftool_tests/README.md | 91 +++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 tools/testing/selftests/bpf/bpftool_tests/README.md diff --git a/tools/testing/selftests/bpf/bpftool_tests/README.md b/tools/testing/selftests/bpf/bpftool_tests/README.md new file mode 100644 index 000000000000..8ee5d656f6f8 --- /dev/null +++ b/tools/testing/selftests/bpf/bpftool_tests/README.md @@ -0,0 +1,91 @@ +## About the testing Framework + +The testing framework uses [RUST's testing framework](https://doc.rust-lang.org/rustc/tests/index.html) +and [libbpf-rs](https://docs.rs/libbpf-rs/latest/libbpf_rs/). + +The former takes care of scheduling tests and reporting their successes/failures. +The latter is used to load bpf programs, maps, and possibly interact with them +programatically through libbpf API. +This allows us to set the environment we want to test and check that `bpftool` +does what we expect. + +This document assumes you have [`cargo` and `rust` installed](https://doc.rust-lang.org/cargo/getting-started/installation.html). + +## Testing bpftool + +This should be no different than typical [`cargo test`](https://doc.rust-lang.org/cargo/commands/cargo-test.html) +but there is a few subtleties to consider when running `bpftool` tests: + +1. bpftool needs to run with root privileges for the most part. So the runner needs to run as root. +1. each tests load a program, possibly modify it, and check expectations. In order to be deterministic, tests need to run serially. + +### Environment variable + +A few environment variable can be used to control the behaviour of the tests: +- `RUST_TEST_THREADS`: This should be set to 1 to run one test at a time and avoid tests to step onto each others. +- `BPFTOOL_PATH`: Allow passing an alternate location for `bpftool`. Default: `/usr/sbin/bpftool` + +### Running the test suite + +Here are a few options to make this happen: + +``` +# build the test binary, extract the test executable location +# and run it with sudo, 1 test at a time. +eval sudo BPFTOOL_PATH=$(pwd)/../bpftool RUST_TEST_THREADS=1 \ + $(cargo test --no-run \ + --message-format=json | jq '. | select(.executable != null ).executable' \ + ) +``` + +or alternatively, one can use the [`CARGO_TARGET_<triple>_RUNNER` environment variable](https://doc.rust-lang.org/cargo/reference/environment-variables.html#:~:text=CARGO_TARGET_%3Ctriple%3E_RUNNER). + +The benefit of that approach is that compilation errors will show directly in the terminal. + +``` +CARGO_TARGET_X86_64_UNKNOWN_LINUX_GNU_RUNNER="sudo -E" \ + BPFTOOL_PATH=$(pwd)/../bpftool \ + RUST_TEST_THREADS=1 \ + cargo test +``` + +### Running tests against built kernel/bpftool + +Using [vmtest](https://github.com/danobi/vmtest): + +``` +$ KERNEL_REPO=~/devel/bpf-next/ +$ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "BPFTOOL_PATH=$KERNEL_REPO/tools/bpf/bpftool/bpftool RUST_TEST_THREADS=1 cargo test" +=> bzImage +===> Booting +===> Setting up VM +===> Running command + Finished test [unoptimized + debuginfo] target(s) in 2.06s + Running unittests src/main.rs (target/debug/deps/bpftool_tests-afa5a7eef3cdeafb) + +running 11 tests +test bpftool_tests::run_bpftool ... ok +test bpftool_tests::run_bpftool_map_dump_id ... ok +test bpftool_tests::run_bpftool_map_list ... ok +test bpftool_tests::run_bpftool_map_pids ... ok +test bpftool_tests::run_bpftool_prog_list ... ok +test bpftool_tests::run_bpftool_prog_pids ... ok +test bpftool_tests::run_bpftool_prog_show_id ... ok +test bpftool_tests::run_bpftool_struct_ops_can_unregister_id ... ok +test bpftool_tests::run_bpftool_struct_ops_can_unregister_name ... ok +test bpftool_tests::run_bpftool_struct_ops_dump_name ... ok +test bpftool_tests::run_bpftool_struct_ops_list ... ok + +test result: ok. 11 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 1.88s +``` + +the return code will be 0 on success, non-zero otherwise. + + +## Caveat + +Currently, libbpf-sys crate either uses a vendored libbpf, or the system one. +This could possibly limit tests against features that are being introduced. + +That being said, this is not a blocker now, and can be fixed upstream. +https://github.com/libbpf/libbpf-sys/issues/70 tracks this on libbpf-sys side. -- 2.39.3
