Re: [PATCH RFC 2/3] samples/bpf: Add define __EMITTING_BPF__ when building BPF

[David Miller]

From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Date: Fri, 16 Jun 2017 12:24:06 +0200

> On 06/16/2017 12:35 AM, David Daney wrote:
>> ... this allows gating of inline assembly code that causes llvm to
>> fail when emitting BPF.
>>
>> Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> 
> I don't have a better idea at the moment, perhaps there could be
> a clang rewrite plugin that would ignore all inline assembly code
> since this is never used from BPF progs. Hmm. Really ugly that
> we have to add this __EMITTING_BPF__ into arch asm files, but I
> don't have a better idea for an immediate workaround right now ...
> I would really prefer if we could avoid just for the sake of the
> kernel samples going down the road of adding a
> !defined(__EMITTING_BPF__)
> into a uapi asm header for mips, though. Is this coming from
> networking sample code or rather tracing?

The problem is that we include the arch include/asm files at all.

When we build bpf stuff, we should have a set of asm/ files
specifically for builds targetting BPF.

Let's just fix this right and stop putting all of these hacks in.

Thank you.