From: Jakub Sitnicki <jakub@cloudflare.com>
To: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
bpf <bpf@vger.kernel.org>, Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
kernel-team <kernel-team@cloudflare.com>,
Yonghong Song <yhs@fb.com>
Subject: Re: [PATCH bpf-next v2 2/2] selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup
Date: Thu, 17 Feb 2022 17:11:13 +0100 [thread overview]
Message-ID: <87fsohea8q.fsf@cloudflare.com> (raw)
In-Reply-To: <e0999e46e5332ca79bdfe4d9b9d7f17e4366a340.camel@linux.ibm.com>
On Thu, Feb 17, 2022 at 03:18 PM +01, Ilya Leoshkevich wrote:
> On Wed, 2022-02-16 at 13:44 -0800, Andrii Nakryiko wrote:
>> On Wed, Feb 9, 2022 at 10:43 AM Jakub Sitnicki <jakub@cloudflare.com>
>> wrote:
[...]
>> > + /* Load from remote_port field with zero padding (backward
>> > compatibility) */
>> > + val_u32 = *(__u32 *)&ctx->remote_port;
>> > + if (val_u32 != bpf_htonl(bpf_ntohs(SRC_PORT) << 16))
>> > + return SK_DROP;
>> > +
>>
>> Jakub, can you please double check that your patch set doesn't break
>> big-endian architectures? I've noticed that our s390x test runner is
>> now failing in the sk_lookup selftest. See [0]. Also CC'ing Ilya.
>
> I agree that this looks like an endianness issue. The new check seems
> to make little sense on big-endian to me, so I would just #ifdef it
> out.
We have a very similar check for a load from context in
progs/test_sock_fields.c, which is not causing problems:
static __noinline bool sk_dst_port__load_word(struct bpf_sock *sk)
{
__u32 *word = (__u32 *)&sk->dst_port;
return word[0] == bpf_htonl(0xcafe0000);
}
So I think I just messed something up here. Will dig into it.
[...]
next prev parent reply other threads:[~2022-02-17 16:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-09 18:43 [PATCH bpf-next v2 0/2] Split bpf_sk_lookup remote_port field Jakub Sitnicki
2022-02-09 18:43 ` [PATCH bpf-next v2 1/2] bpf: Make remote_port field in struct bpf_sk_lookup 16-bit wide Jakub Sitnicki
2022-02-09 18:43 ` [PATCH bpf-next v2 2/2] selftests/bpf: Cover 4-byte load from remote_port in bpf_sk_lookup Jakub Sitnicki
2022-02-16 21:44 ` Andrii Nakryiko
2022-02-17 14:18 ` Ilya Leoshkevich
2022-02-17 16:11 ` Jakub Sitnicki [this message]
2022-02-19 14:37 ` Jakub Sitnicki
2022-02-21 18:34 ` Jakub Sitnicki
2022-02-09 19:50 ` [PATCH bpf-next v2 0/2] Split bpf_sk_lookup remote_port field patchwork-bot+netdevbpf
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