On Sun, May 29, 2022 at 3:06 PM Daniel Xu <dxu@xxxxxxxxx> wrote: > > This patchset adds PROG_TEST_RUN support to BPF_PROG_TYPE_KPROBE progs. > On top of being generally useful for unit testing kprobe progs, this > feature more specifically helps solve a relability problem with bpftrace > BEGIN and END probes. > > BEGIN and END probes are run exactly once at the beginning and end of a > bpftrace tracing session, respectively. bpftrace currently implements > the probes by creating two dummy functions and attaching the BEGIN and > END progs, if defined, to those functions and calling the dummy > functions as appropriate. This works pretty well most of the time except > for when distros strip symbols from bpftrace. Every now and then this > happens and users get confused. Having PROG_TEST_RUN support will help > solve this issue by allowing us to directly trigger uprobes from > userspace. > > Admittedly, this is a pretty specific problem and could probably be > solved other ways. However, PROG_TEST_RUN also makes unit testing more > convenient, especially as users start building more complex tracing > applications. So I see this as killing two birds with one stone. We have BPF_PROG_RUN which is an alias of BPF_PROG_TEST_RUN. I guess that's a better name for the BEGIN/END use case. Have you checked out bpf_prog_test_run_raw_tp()? AFAICT, it works as good as kprobe for this use case. Thanks, Song
