On Tue, 2024-01-02 at 11:00 -0800, Andrii Nakryiko wrote: > Add a few extra cases of global funcs with context arguments. This time > rely on "arg:ctx" decl_tag (__arg_ctx macro), but put it next to > "classic" cases where context argument has to be of an exact type that > BPF verifier expects (e.g., bpf_user_pt_regs_t for kprobe/uprobe). > > Colocating all these cases separately from other global func args that > rely on arg:xxx decl tags (in verifier_global_subprogs.c) allows for > simpler backwards compatibility testing on old kernels. All the cases in > test_global_func_ctx_args.c are supposed to work on older kernels, which > was manually validated during development. > > Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx> > Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> > --- At first I thought that we would need to add a new CI job that would run these tests for some older kernel version. However, the transformation of the sub-program parameters happens unconditionally. So it should be possible to read BTF for some of the programs after they are loaded and check if transformation is applied as expected. Thus allowing to check __arg_ctx handling on libbpf side w/o the need to run on old kernel. I think it's worth it to add such test, wdyt?
