On Wed, Mar 29, 2023 at 12:56 AM Andrii Nakryiko <andrii@xxxxxxxxxx> wrote: > > Add selftests validating BPF_LOG_FIXED behavior, which used to be the > only behavior, and now default rotating BPF verifier log, which returns > just up to last N bytes of full verifier log, instead of returning > -ENOSPC. > > To stress test correctness of in-kernel verifier log logic, we force it > to truncate program's verifier log to all lengths from 1 all the way to > its full size (about 450 bytes today). This was a useful stress test > while developing the feature. > > For both fixed and rotating log modes we expect -ENOSPC if log contents > doesn't fit in user-supplied log buffer. > > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> Acked-by: Lorenz Bauer <lmb@xxxxxxxxxxxxx> > + /* validate BPF_LOG_FIXED works as verifier log used to work, that is: > + * we get -ENOSPC and beginning of the full verifier log. This only > + * works for log_level 2 and log_level 1 + failed program. For log > + * level 2 we don't reset log at all. For log_level 1 + failed program > + * we don't get to verification stats output. With log level 1 > + * for successful program final result will be just verifier stats. > + * But if provided too short log buf, kernel will NULL-out log->ubuf Out of curiousity: why is ubuf NULLed? Is that something we could change?
