mirror of https://github.com/aya-rs/aya
Merge pull request #467 from MatteoNardi/relocation_tests
Add integration tests for BTF relocationspull/482/head
Alessandro Decina
2 years ago
committed by
GitHub
commit
4cc0ea09e0
@ -1,74 +1,21 @@
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use log::info;
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use libtest_mimic::{Arguments, Trial};
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mod tests;
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use tests::IntegrationTest;
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use clap::Parser;
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#[derive(Debug, Parser)]
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#[clap(author, version, about, long_about = None)]
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#[clap(propagate_version = true)]
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pub struct RunOptions {
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#[clap(short, long, value_parser)]
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tests: Option<Vec<String>>,
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}
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#[derive(Debug, Parser)]
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struct Cli {
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#[clap(subcommand)]
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command: Option<Command>,
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}
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#[derive(Debug, Parser)]
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enum Command {
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/// Run one or more tests: ... -- run -t test1 -t test2
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Run(RunOptions),
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/// List all the tests: ... -- list
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List,
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}
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macro_rules! exec_test {
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($test:expr) => {{
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info!("Running {}", $test.name);
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($test.test_fn)();
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}};
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}
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macro_rules! exec_all_tests {
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() => {{
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for t in inventory::iter::<IntegrationTest> {
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exec_test!(t)
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}
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}};
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}
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fn main() -> anyhow::Result<()> {
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fn main() {
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env_logger::init();
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let cli = Cli::parse();
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match &cli.command {
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Some(Command::Run(opts)) => match &opts.tests {
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Some(tests) => {
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for t in inventory::iter::<IntegrationTest> {
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if tests.contains(&t.name.into()) {
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exec_test!(t)
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}
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}
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}
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None => {
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exec_all_tests!()
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}
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},
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Some(Command::List) => {
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for t in inventory::iter::<IntegrationTest> {
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info!("{}", t.name);
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}
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}
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None => {
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exec_all_tests!()
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}
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}
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let mut args = Arguments::from_args();
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// Force to run single-threaded
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args.test_threads = Some(1);
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let tests = inventory::iter::<IntegrationTest>
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.into_iter()
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.map(|test| {
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Trial::test(test.name, move || {
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(test.test_fn)();
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Ok(())
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})
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})
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.collect();
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libtest_mimic::run(&args, tests).exit();
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}
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@ -0,0 +1,256 @@
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use anyhow::{Context, Result};
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use std::{path::PathBuf, process::Command, thread::sleep, time::Duration};
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use tempfile::TempDir;
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use aya::{maps::Array, programs::TracePoint, BpfLoader, Btf, Endianness};
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use super::{integration_test, IntegrationTest};
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#[integration_test]
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fn relocate_field() {
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let test = RelocationTest {
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local_definition: r#"
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struct foo {
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__u8 a;
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__u8 b;
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__u8 c;
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__u8 d;
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};
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"#,
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target_btf: r#"
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struct foo {
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__u8 a;
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__u8 c;
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__u8 b;
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__u8 d;
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} s1;
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"#,
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relocation_code: r#"
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__u8 memory[] = {1, 2, 3, 4};
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__u32 value = BPF_CORE_READ((struct foo *)&memory, c);
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"#,
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}
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.build()
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.unwrap();
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assert_eq!(test.run().unwrap(), 2);
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assert_eq!(test.run_no_btf().unwrap(), 3);
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}
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#[integration_test]
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fn relocate_enum() {
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let test = RelocationTest {
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local_definition: r#"
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enum foo { D = 1 };
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"#,
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target_btf: r#"
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enum foo { D = 4 } e1;
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"#,
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relocation_code: r#"
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__u32 value = bpf_core_enum_value(enum foo, D);
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"#,
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}
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.build()
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.unwrap();
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assert_eq!(test.run().unwrap(), 4);
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assert_eq!(test.run_no_btf().unwrap(), 1);
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}
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#[integration_test]
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fn relocate_pointer() {
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let test = RelocationTest {
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local_definition: r#"
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struct foo {};
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struct bar { struct foo *f; };
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"#,
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target_btf: r#"
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struct foo {};
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struct bar { struct foo *f; };
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"#,
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relocation_code: r#"
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__u8 memory[] = {42, 0, 0, 0, 0, 0, 0, 0};
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struct foo *f = BPF_CORE_READ((struct bar *)&memory, f);
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__u32 value = ((__u64) f);
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"#,
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}
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.build()
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.unwrap();
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assert_eq!(test.run().unwrap(), 42);
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assert_eq!(test.run_no_btf().unwrap(), 42);
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}
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/// Utility code for running relocation tests:
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/// - Generates the eBPF program using probided local definition and relocation code
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/// - Generates the BTF from the target btf code
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struct RelocationTest {
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/// Data structure definition, local to the eBPF program and embedded in the eBPF bytecode
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local_definition: &'static str,
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/// Target data structure definition. What the vmlinux would actually contain.
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target_btf: &'static str,
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/// Code executed by the eBPF program to test the relocation.
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/// The format should be:
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// __u8 memory[] = { ... };
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// __u32 value = BPF_CORE_READ((struct foo *)&memory, ...);
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//
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// The generated code will be executed by attaching a tracepoint to sched_switch
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// and emitting `__u32 value` an a map. See the code template below for more details.
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relocation_code: &'static str,
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}
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impl RelocationTest {
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/// Build a RelocationTestRunner
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fn build(&self) -> Result<RelocationTestRunner> {
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Ok(RelocationTestRunner {
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ebpf: self.build_ebpf()?,
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btf: self.build_btf()?,
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})
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}
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/// - Generate the source eBPF filling a template
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/// - Compile it with clang
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fn build_ebpf(&self) -> Result<Vec<u8>> {
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let local_definition = self.local_definition;
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let relocation_code = self.relocation_code;
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let (_tmp_dir, compiled_file) = compile(&format!(
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r#"
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#include <linux/bpf.h>
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#include <bpf/bpf_core_read.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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{local_definition}
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struct {{
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__uint(type, BPF_MAP_TYPE_ARRAY);
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__type(key, __u32);
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__type(value, __u32);
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__uint(max_entries, 1);
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}} output_map SEC(".maps");
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SEC("tracepoint/bpf_prog") int bpf_prog(void *ctx) {{
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__u32 key = 0;
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{relocation_code}
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bpf_map_update_elem(&output_map, &key, &value, BPF_ANY);
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return 0;
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}}
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char _license[] SEC("license") = "GPL";
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"#
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))
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.context("Failed to compile eBPF program")?;
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let bytecode =
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std::fs::read(compiled_file).context("Error reading compiled eBPF program")?;
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Ok(bytecode)
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}
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/// - Generate the target BTF source with a mock main()
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/// - Compile it with clang
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/// - Extract the BTF with llvm-objcopy
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fn build_btf(&self) -> Result<Btf> {
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let target_btf = self.target_btf;
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let relocation_code = self.relocation_code;
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// BTF files can be generated and inspected with these commands:
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// $ clang -c -g -O2 -target bpf target.c
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// $ pahole --btf_encode_detached=target.btf -V target.o
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// $ bpftool btf dump file ./target.btf format c
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let (tmp_dir, compiled_file) = compile(&format!(
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r#"
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#include <linux/bpf.h>
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#include <bpf/bpf_core_read.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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{target_btf}
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int main() {{
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// This is needed to make sure to emit BTF for the defined types,
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// it could be dead code eliminated if we don't.
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{relocation_code};
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return value;
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}}
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"#
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))
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.context("Failed to compile BTF")?;
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Command::new("llvm-objcopy")
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.current_dir(tmp_dir.path())
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.args(["--dump-section", ".BTF=target.btf"])
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.arg(compiled_file)
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.status()
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.context("Failed to run llvm-objcopy")?
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.success()
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.then_some(())
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.context("Failed to extract BTF")?;
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let btf = Btf::parse_file(tmp_dir.path().join("target.btf"), Endianness::default())
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.context("Error parsing generated BTF")?;
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Ok(btf)
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}
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}
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/// Compile an eBPF program and return the path of the compiled object.
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/// Also returns a TempDir handler, dropping it will clear the created dicretory.
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fn compile(source_code: &str) -> Result<(TempDir, PathBuf)> {
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let tmp_dir = tempfile::tempdir().context("Error making temp dir")?;
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let source = tmp_dir.path().join("source.c");
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std::fs::write(&source, source_code).context("Writing bpf program failed")?;
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Command::new("clang")
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.current_dir(&tmp_dir)
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.args(["-c", "-g", "-O2", "-target", "bpf"])
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// NOTE: these tests depend on libbpf, LIBBPF_INCLUDE must point its headers.
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// This is set automatically by the integration-test xtask.
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.args([
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"-I",
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&std::env::var("LIBBPF_INCLUDE").context("LIBBPF_INCLUDE not set")?,
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])
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.arg(&source)
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.status()
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.context("Failed to run clang")?
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.success()
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.then_some(())
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.context("Failed to compile eBPF source")?;
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Ok((tmp_dir, source.with_extension("o")))
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}
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struct RelocationTestRunner {
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ebpf: Vec<u8>,
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btf: Btf,
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}
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impl RelocationTestRunner {
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/// Run test and return the output value
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fn run(&self) -> Result<u32> {
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self.run_internal(true).context("Error running with BTF")
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}
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/// Run without loading btf
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fn run_no_btf(&self) -> Result<u32> {
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self.run_internal(false)
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.context("Error running without BTF")
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}
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fn run_internal(&self, with_relocations: bool) -> Result<u32> {
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let mut loader = BpfLoader::new();
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if with_relocations {
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loader.btf(Some(&self.btf));
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} else {
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loader.btf(None);
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}
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let mut bpf = loader.load(&self.ebpf).context("Loading eBPF failed")?;
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let program: &mut TracePoint = bpf
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.program_mut("bpf_prog")
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.context("bpf_prog not found")?
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.try_into()
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.context("program not a tracepoint")?;
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program.load().context("Loading tracepoint failed")?;
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// Attach to sched_switch and wait some time to make sure it executed at least once
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program
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.attach("sched", "sched_switch")
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.context("attach failed")?;
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sleep(Duration::from_millis(1000));
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// To inspect the loaded eBPF bytecode, increse the timeout and run:
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// $ sudo bpftool prog dump xlated name bpf_prog
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let output_map: Array<_, u32> = bpf.take_map("output_map").unwrap().try_into().unwrap();
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let key = 0;
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output_map.get(&key, 0).context("Getting key 0 failed")
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}
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}
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