On Fri, 2025-01-31 at 11:28 -0800, Amery Hung wrote:
> From: Amery Hung <amery.hung@xxxxxxxxxxxxx>
>
> Currently, add_kfunc_call() is only invoked once before the main
> verification loop. Therefore, the verifier could not find the
> bpf_kfunc_btf_tab of a new kfunc call which is not seen in user defined
> struct_ops operators but introduced in gen_prologue or gen_epilogue
> during do_misc_fixup(). Fix this by searching kfuncs in the patching
> instruction buffer and add them to prog->aux->kfunc_tab.
>
> Signed-off-by: Amery Hung <amery.hung@xxxxxxxxxxxxx>
> ---
Acked-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
[...]
> @@ -20397,6 +20412,10 @@ static int convert_ctx_accesses(struct bpf_verifier_env *env)
> return -ENOMEM;
> env->prog = new_prog;
> delta += cnt - 1;
> +
> + ret = add_kfunc_in_insns(env, epilogue_buf, epilogue_cnt - 1);
Rant: the -1 here is a bit confusing, it is second time I forget that
last instruction of the epilogue has to be some kind of control flow,
and last instruction of the prologue has to be first instruction
of the program.
> + if (ret < 0)
> + return ret;
> }
> }
>
[...]
