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aya+ebpf: Add integration test for reading perf_events from bpf program
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,56 @@ | ||
| #![no_std] | ||
| #![no_main] | ||
|
|
||
| use aya_bpf::{ | ||
| bindings::bpf_perf_event_value, | ||
| helpers::bpf_get_smp_processor_id, | ||
| macros::{map, perf_event}, | ||
| maps::PerfEventArray, | ||
| programs::PerfEventContext, | ||
| }; | ||
|
|
||
| #[repr(C)] | ||
| struct EventData { | ||
| value: u64, | ||
| cpu_id: u32, | ||
| tag: u8, | ||
| } | ||
|
|
||
| /// Input map: file descriptors of the perf events, obtained by calling | ||
| /// `perf_event_open` in user space. | ||
| #[map] | ||
| static mut DESCRIPTORS: PerfEventArray<i32> = PerfEventArray::with_max_entries(1, 0); | ||
|
|
||
| #[map] | ||
| static mut OUTPUT: PerfEventArray<EventData> = PerfEventArray::with_max_entries(1, 0); | ||
|
|
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| #[perf_event] | ||
| pub fn on_perf_event(ctx: PerfEventContext) -> i64 { | ||
| match read_event().map(|res| write_output(&ctx, res)) { | ||
| Ok(_) => 0, | ||
| Err(e) => e, | ||
| } | ||
| } | ||
|
|
||
| fn read_event() -> Result<EventData, i64> { | ||
| // read the event value using the file descriptor in the DESCRIPTORS array | ||
| let event: bpf_perf_event_value = unsafe { DESCRIPTORS.read_current_cpu() }?; | ||
|
|
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| let cpu_id = unsafe { bpf_get_smp_processor_id() }; | ||
| let res = EventData { | ||
| value: event.counter, | ||
| cpu_id, | ||
| tag: 0xAB, | ||
| }; | ||
| Ok(res) | ||
| } | ||
|
|
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| fn write_output(ctx: &PerfEventContext, output: EventData) -> Result<(), i64> { | ||
| unsafe { OUTPUT.output_current_cpu(ctx, &output) } | ||
| } | ||
|
|
||
| #[cfg(not(test))] | ||
| #[panic_handler] | ||
| fn panic(_info: &core::panic::PanicInfo) -> ! { | ||
| loop {} | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,82 @@ | ||
| use std::os::fd::OwnedFd; | ||
|
|
||
| use aya::maps::PerfEventArray; | ||
| use aya::programs::perf_event::{perf_event_open, PerfEventScope}; | ||
| use aya::programs::{PerfTypeId, SamplePolicy}; | ||
| use aya_obj::generated::perf_sw_ids; | ||
| use test_log::test; | ||
|
|
||
| #[derive(Debug)] | ||
| #[repr(C)] | ||
| struct EventData { | ||
| value: u64, | ||
| cpu_id: u32, | ||
| tag: u8, | ||
| } | ||
|
|
||
| #[test] | ||
| fn perf_event_read_from_kernel() { | ||
| // load bpf program | ||
| let mut bpf = Bpf::load(PERF_EVENTS); | ||
| let mut descriptors = PerfEventArray::<i32>::try_from(bpf.map_mut("DESCRIPTORS").unwrap()).unwrap(); | ||
| let mut bpf_output = PerfEventArray::<EventData>::try_from(bpf.map_mut("OUTPUT").unwrap()).unwrap(); | ||
|
|
||
| // open a perf_event | ||
| // Beware: this returns an `OwnedFd`, which means that the file descriptor is closed at the end of the scope | ||
| let event_fd: OwnedFd = perf_event_open( | ||
| PERF_TYPE_HARDWARE, | ||
| PERF_COUNT_HW_INSTRUCTIONS, | ||
| PerfEventScope::CallingProcessAnyCpu, | ||
| None, | ||
| None, | ||
| 0, | ||
| ) | ||
| .unwrap(); | ||
|
|
||
| // pass pointer to bpf array | ||
| descriptors.set(0, event_fd.into()); | ||
|
|
||
| // load program | ||
| let program: &mut PerfEvent = bpf.program_mut("on_perf_event").unwrap().try_into().unwrap(); | ||
| program.load().expect("failed to load the bpf program"); | ||
|
|
||
| // get buffer to poll the events | ||
| const BUF_PAGE_COUNT: u32 = 1; | ||
| let buf = bpf_output | ||
| .open(0, Some(buf_page_count)) | ||
| .expect("failed to open output buffer to poll events"); | ||
|
|
||
| // attach program | ||
| const CPU_ID: u32 = 0; | ||
| program.attach( | ||
| PerfTypeId::Software, | ||
| perf_sw_ids::PERF_COUNT_SW_CPU_CLOCK as u64, | ||
| PerfEventScope::AllProcessesOneCpu { cpu: CPU_ID }, | ||
| SamplePolicy::Frequency(1), | ||
| ); | ||
|
|
||
| // sleep a little bit, then poll the values from the buffer | ||
| std::thread::sleep(Duration::from_secs(2)); | ||
| assert!( | ||
| buf.readable(), | ||
| "the buffer should have been filled by the bpf program" | ||
| ); | ||
|
|
||
| // read the events and check that the returned data is correct | ||
| let mut events_data = [BytesMut, BUF_PAGE_COUNT] = std::array::from_fn(|_| BytesMut::new()); | ||
| let event_stats = buf | ||
| .read_events(&mut events_data) | ||
| .expect("failed to poll events"); | ||
|
|
||
| for data_buf in events_data.iter_mut().take(events_stats.read) { | ||
| // You must ensure that the definition of the struct (here `EventData`) is the same | ||
| // in the userspace and in the bpf program. | ||
| let ptr = data_buf.as_ptr() as *const EventData; | ||
| let data: EventData = unsafe { ptr.read_unaligned() }; | ||
|
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| assert_eq!(data.cpu_id, CPU_ID, "unexpected data: {}", data); | ||
| assert_eq!(data.tag, 0xAB, "unexpected data: {}", data); | ||
| } | ||
|
|
||
| Ok(()) | ||
| } |