From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jakub Kicinski <kubakici@wp.pl>
Subject: Re: [PATCH bpf-next] bpf: introduce BPF_JIT_ALWAYS_ON config
Date: Mon, 8 Jan 2018 16:02:25 -0800
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        <1f0c1df2-3e27-a0ef-90b2-41ce499af14b@iogearbox.net>
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Cc: Alexei Starovoitov <ast@kernel.org>, davem@davemloft.net,
        torvalds@linux-foundation.org, jannh@google.com,
        alan@linux.intel.com, netdev@vger.kernel.org, kernel-team@fb.com
To: Daniel Borkmann <daniel@iogearbox.net>
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On Mon, 8 Jan 2018 22:59:04 +0100, Daniel Borkmann wrote:
> > @@ -1453,6 +1457,11 @@ struct bpf_prog *bpf_prog_select_runtime(struct bpf_prog *fp, int *err)
> >  	 */
> >  	*err = bpf_check_tail_call(fp);
> >  
> > +#ifdef CONFIG_BPF_JIT_ALWAYS_ON
> > +	if (!fp->jited)
> > +		*err = -ENOTSUPP;
> > +#endif  

I think programs JITed for offload won't have fp->jited set, but
those are pretty safe from CPU bugs.  Should we set fp->jited = 1; in
bpf_prog_offload_compile()?  Just throwing "&& !bpf_prog_is_dev_bound()"
in here seems cleaner to me.

FWIW if you have netdevsim compiled and recent iproute2, this will
work to check:

# ip link add type netdevsim
# ip link set netdevsim0 xdpoffload obj ~/xdp/pass.o