From: David Ahern <dsahern@gmail•com>
To: Jesper Dangaard Brouer <brouer@redhat•com>,
David Ahern <dsahern@kernel•org>
Cc: netdev@vger•kernel.org, davem@davemloft•net, kuba@kernel•org,
toke@redhat•com, daniel@iogearbox•net, john.fastabend@gmail•com,
ast@kernel•org, kafai@fb•com, songliubraving@fb•com, yhs@fb•com,
andriin@fb•com
Subject: Re: [PATCH bpf-next 1/5] bpf: Handle 8-byte values in DEVMAP and DEVMAP_HASH
Date: Wed, 27 May 2020 07:56:25 -0600 [thread overview]
Message-ID: <c58f11be-af67-baff-bd70-753ca84de0dd@gmail.com> (raw)
In-Reply-To: <20200527122612.579fbb25@carbon>
On 5/27/20 4:26 AM, Jesper Dangaard Brouer wrote:
>> @@ -108,9 +118,13 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
>> u64 cost = 0;
>> int err;
>>
>> - /* check sanity of attributes */
>> + /* check sanity of attributes. 2 value sizes supported:
>> + * 4 bytes: ifindex
>> + * 8 bytes: ifindex + prog fd
>> + */
>> if (attr->max_entries == 0 || attr->key_size != 4 ||
>> - attr->value_size != 4 || attr->map_flags & ~DEV_CREATE_FLAG_MASK)
>> + (attr->value_size != 4 && attr->value_size != 8) ||
>
> IMHO we really need to leverage BTF here, as I'm sure we need to do more
> extensions, and this size matching will get more and more unmaintainable.
>
> With BTF in place, dumping the map via bpftool, will also make the
> fields "self-documenting".
>
> I will try to implement something that uses BTF for this case (and cpumap).
>
as mentioned in a past response, BTF does not make any fields special
and this code should not assume it either. You need to know precisely
which 4 bytes is the program fd that needs to be looked up, and that
AFAIK is beyond the scope of BTF.
next prev parent reply other threads:[~2020-05-27 13:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-27 1:09 [PATCH bpf-next 0/5] bpf: Add support for XDP programs in DEVMAP entries David Ahern
2020-05-27 1:09 ` [PATCH bpf-next 1/5] bpf: Handle 8-byte values in DEVMAP and DEVMAP_HASH David Ahern
2020-05-27 10:26 ` Jesper Dangaard Brouer
2020-05-27 13:56 ` David Ahern [this message]
2020-05-27 14:57 ` Toke Høiland-Jørgensen
2020-05-27 15:24 ` David Ahern
2020-05-27 14:27 ` David Ahern
2020-05-27 15:30 ` Jesper Dangaard Brouer
2020-05-27 18:38 ` David Ahern
2020-05-27 1:09 ` [PATCH bpf-next 2/5] bpf: Add support to attach bpf program to a devmap entry David Ahern
2020-05-27 10:01 ` Toke Høiland-Jørgensen
2020-05-27 14:02 ` David Ahern
2020-05-27 14:58 ` Toke Høiland-Jørgensen
2020-05-27 1:09 ` [PATCH bpf-next 3/5] xdp: Add xdp_txq_info to xdp_buff David Ahern
2020-05-27 1:09 ` [PATCH bpf-next 4/5] bpftool: Add SEC name for xdp programs attached to device map David Ahern
2020-05-27 10:02 ` Toke Høiland-Jørgensen
2020-05-27 14:03 ` David Ahern
2020-05-27 15:01 ` Toke Høiland-Jørgensen
2020-05-27 15:43 ` Jesper Dangaard Brouer
2020-05-27 1:09 ` [PATCH bpf-next 5/5] selftest: Add tests for XDP programs in devmap entries David Ahern
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