From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Sami Tolvanen <samitolvanen@google.com>
Cc: "Björn Töpel" <bjorn.topel@intel.com>,
"Yonghong Song" <yhs@fb.com>,
"Alexei Starovoitov" <ast@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Kees Cook" <keescook@chromium.org>, "Martin Lau" <kafai@fb.com>,
"Song Liu" <songliubraving@fb.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"bpf@vger.kernel.org" <bpf@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Jesper Dangaard Brouer" <brouer@redhat.com>
Subject: Re: [PATCH] bpf: validate bpf_func when BPF_JIT is enabled
Date: Thu, 12 Sep 2019 11:46:39 +0100 [thread overview]
Message-ID: <87sgp1ssfk.fsf@toke.dk> (raw)
In-Reply-To: <CABCJKufCwjXQ6a4oLjywDmxY2apUZ1yop-5+qty82bfwV-QTAA@mail.gmail.com>
Sami Tolvanen <samitolvanen@google.com> writes:
> On Wed, Sep 11, 2019 at 5:09 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>>
>> Björn Töpel <bjorn.topel@intel.com> writes:
>> > I ran the "xdp_rxq_info" sample with and without Sami's patch:
>>
>> Thanks for doing this!
>
> Yes, thanks for testing this Björn!
>
>> Or (1/22998700 - 1/23923874) * 10**9 == 1.7 nanoseconds of overhead.
>>
>> I guess that is not *too* bad; but it's still chipping away at
>> performance; anything we could do to lower the overhead?
>
> The check is already rather minimal, but I could move this to a static
> inline function to help ensure the compiler doesn't generate an
> additional function call for this. I'm also fine with gating this
> behind a separate config option, but I'm not sure if that's worth it.
> Any thoughts?
I think it would be good if you do both. I'm a bit worried that XDP
performance will end up in a "death by a thousand paper cuts" situation,
so I'd rather push back on even relatively small overheads like this; so
being able to turn it off in the config would be good.
Can you share more details about what the "future CFI checking" is
likely to look like?
-Toke
next prev parent reply other threads:[~2019-09-12 10:52 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-09 22:32 [PATCH] bpf: validate bpf_func when BPF_JIT is enabled Sami Tolvanen
2019-09-10 8:37 ` Yonghong Song
2019-09-10 17:22 ` Sami Tolvanen
2019-09-11 7:42 ` Yonghong Song
2019-09-11 10:39 ` Björn Töpel
2019-09-11 12:09 ` Toke Høiland-Jørgensen
2019-09-11 21:07 ` Sami Tolvanen
2019-09-12 10:46 ` Toke Høiland-Jørgensen [this message]
2019-09-12 22:01 ` Sami Tolvanen
2019-09-13 12:19 ` Toke Høiland-Jørgensen
2019-09-11 20:29 ` Sami Tolvanen
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