Adding a selftest for someone else's fix

Note: This will be a casual blog, so excuse my language. It’s mostly stuff for documentation (for my brain). The goal lore.kernel.org is the conversation I came across earlier today. I want to quickly send in a selftest before the original author does to better my understanding of the verifier. Finding out what the fix actually did We will be doing this by backtracing from the function to the function I am familiar with, bpf_check, then we will be finding out how to hit this function by writing a relevant selftest. We will first check if there exists something similar to the selftest we want already, and if it does, we will maybe extend it. “Backtracing” for (i = 0; i < st_ops_desc->arg_info[member_idx].cnt; i++) { A few things, st_ops_desc is a struct of type bpf_struct_ops_desc and arg_info is of the type bpf_struct_ops_arg_info struct bpf_struct_ops_arg_info { struct bpf_ctx_arg_aux *info; u32 cnt; }; That is the info field we want. /* reg_type info for ctx arguments */ struct…