selftests/bpf: Add exception handling selftests for tp_bpf program

2021-11-08T21:17:55Z

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. The test verifies that task_works and task_works->func are 0. Signed-off-by: Alan Maguire Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/1636131046-5982-3-git-send-email-alan.maguire@oracle.com

kernel/tools/testing/selftests/bpf/prog_tests/exhandler.c, branch linux-6.2.y

selftests/bpf: Add exception handling selftests for tp_bpf program