On Thu, Apr 15, 2021 at 12:16 AM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > On Wed, Apr 14, 2021 at 2:21 AM Florent Revest <revest@xxxxxxxxxxxx> wrote: > > > > On Wed, Apr 14, 2021 at 1:21 AM Andrii Nakryiko > > <andrii.nakryiko@xxxxxxxxx> wrote: > > > > > > On Mon, Apr 12, 2021 at 8:38 AM Florent Revest <revest@xxxxxxxxxxxx> wrote: > > > > > > > > This exercises most of the format specifiers. > > > > > > > > Signed-off-by: Florent Revest <revest@xxxxxxxxxxxx> > > > > Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > > > > --- > > > > > > As I mentioned on another patch, we probably need negative tests even > > > more than positive ones. > > > > Agreed. > > > > > I think an easy and nice way to do this is to have a separate BPF > > > skeleton where fmt string and arguments are provided through read-only > > > global variables, so that user-space can re-use the same BPF skeleton > > > to simulate multiple cases. BPF program itself would just call > > > bpf_snprintf() and store the returned result. > > > > Ah, great idea! I was thinking of having one skeleton for each but it > > would be a bit much indeed. > > > > Because the format string needs to be in a read only map though, I > > hope it can be modified from userspace before loading. I'll try it out > > and see :) if it doesn't work I'll just use more skeletons > > You need read-only variables (const volatile my_type). Their contents > are statically verified by BPF verifier, yet user-space can pre-setup > it at runtime. Thanks :) v4 has negative fmt tests
