Re: [PATCH v7 bpf-next 06/10] tracepoint: compute num_args at build time

On Wed, 28 Mar 2018 10:10:34 -0700
Alexei Starovoitov [off-list ref] wrote:

quoted

and have:

	u64 tp_offset = (u64)tp - (u64)_sdata;

	if (WARN_ON(tp_offset > UINT_MAX)
		return -EINVAL;

	 btp->tp_offset = (u32)tp_offset;  

above math has to be build time constant, so warn_on likely
won't work.

Right, it would require a BUILD_BUG_ON.

imo the whole thing is too fragile and obscure.
I suggest to compress this 8 bytes * num_of_tracepoints later.
Especially would be good to do it in one way for
bpf_raw_event_map, ftrace and other places.

Fair enough. We can defer this shrinkage to another time. I only
suggested it here over your concern for the added bloat.

-- Steve