Re: [PATCH v2 bpf-next 2/2] selftests/bpf: add exception handling selftests for tp_bpf program

[Andrii Nakryiko]

On Fri, Nov 5, 2021 at 10:11 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote:
>
> Exception handling is triggered in BPF tracing programs when
> a NULL pointer is dereferenced; the exception handler zeroes the
> target register and execution of the BPF program progresses.
>
> To test exception handling then, we need to trigger a NULL pointer
> dereference for a field which should never be zero; if it is, the
> only explanation is the exception handler ran.  task->task_works
> is the NULL pointer chosen (for a new task from fork() no work
> is associated), and the task_works->func field should not be zero
> if task_works is non-NULL.  Test verifies task_works and
> task_works->func are 0.
>
> Signed-off-by: Alan Maguire <alan.maguire@xxxxxxxxxx>
> ---
>  tools/testing/selftests/bpf/prog_tests/exhandler.c | 43 ++++++++++++++++++++++
>  tools/testing/selftests/bpf/progs/exhandler_kern.c | 43 ++++++++++++++++++++++
>  2 files changed, 86 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/prog_tests/exhandler.c
>  create mode 100644 tools/testing/selftests/bpf/progs/exhandler_kern.c
>

The test looks good, thank you!

Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>

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