From: Yonghong Song <yhs@fb.com>
To: Martin Lau <kafai@fb.com>, "bpf@vger.kernel.org" <bpf@vger.kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
David Miller <davem@davemloft.net>,
Kernel Team <Kernel-team@fb.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next 04/13] bpf: Support bitfield read access in btf_struct_access
Date: Mon, 16 Dec 2019 22:05:47 +0000 [thread overview]
Message-ID: <906ffb48-1122-e63f-b8fc-e619e7be3310@fb.com> (raw)
In-Reply-To: <20191214004746.1652586-1-kafai@fb.com>
On 12/13/19 4:47 PM, Martin KaFai Lau wrote:
> This patch allows bitfield access as a scalar. It currently limits
> the access to sizeof(u64) and upto the end of the struct. It is needed
> in a later bpf-tcp-cc example that reads bitfield from
> inet_connection_sock and tcp_sock.
>
> Signed-off-by: Martin KaFai Lau <kafai@fb.com>
> ---
> kernel/bpf/btf.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
> index 6e652643849b..011194831499 100644
> --- a/kernel/bpf/btf.c
> +++ b/kernel/bpf/btf.c
> @@ -3744,10 +3744,6 @@ int btf_struct_access(struct bpf_verifier_log *log,
> }
>
> for_each_member(i, t, member) {
> - if (btf_member_bitfield_size(t, member))
> - /* bitfields are not supported yet */
> - continue;
> -
> /* offset of the field in bytes */
> moff = btf_member_bit_offset(t, member) / 8;
> if (off + size <= moff)
> @@ -3757,6 +3753,15 @@ int btf_struct_access(struct bpf_verifier_log *log,
> if (off < moff)
> continue;
>
> + if (btf_member_bitfield_size(t, member)) {
> + if (off == moff &&
> + !(btf_member_bit_offset(t, member) % 8) &&
This check '!(btf_member_bit_offset(t, member) % 8)' is not needed.
> + size <= sizeof(u64) &&
This one is not needed since verifier gets 'size' from load/store
instructions which is guaranteed to be <= sizeof(u64).
> + off + size <= t->size)
> + return SCALAR_VALUE;
> + continue;
> + }
> +
> /* type of the field */
> mtype = btf_type_by_id(btf_vmlinux, member->type);
> mname = __btf_name_by_offset(btf_vmlinux, member->name_off);
>
next prev parent reply other threads:[~2019-12-16 22:06 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-14 0:47 [PATCH bpf-next 00/13] Introduce BPF STRUCT_OPS Martin KaFai Lau
2019-12-14 0:47 ` [PATCH bpf-next 01/13] bpf: Save PTR_TO_BTF_ID register state when spilling to stack Martin KaFai Lau
2019-12-16 19:48 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 02/13] bpf: Avoid storing modifier to info->btf_id Martin KaFai Lau
2019-12-16 21:34 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 03/13] bpf: Add enum support to btf_ctx_access() Martin KaFai Lau
2019-12-16 21:36 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 04/13] bpf: Support bitfield read access in btf_struct_access Martin KaFai Lau
2019-12-16 22:05 ` Yonghong Song [this message]
2019-12-14 0:47 ` [PATCH bpf-next 05/13] bpf: Introduce BPF_PROG_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-17 6:14 ` Yonghong Song
2019-12-18 16:41 ` Martin Lau
2019-12-14 0:47 ` [PATCH bpf-next 06/13] bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-17 7:48 ` [Potential Spoof] " Yonghong Song
2019-12-20 7:22 ` Martin Lau
2019-12-20 16:52 ` Martin Lau
2019-12-20 18:41 ` Andrii Nakryiko
2019-12-14 0:47 ` [PATCH bpf-next 07/13] bpf: tcp: Support tcp_congestion_ops in bpf Martin KaFai Lau
2019-12-17 17:36 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 08/13] bpf: Add BPF_FUNC_tcp_send_ack helper Martin KaFai Lau
2019-12-17 17:41 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 09/13] bpf: Add BPF_FUNC_jiffies Martin KaFai Lau
2019-12-14 1:59 ` Eric Dumazet
2019-12-14 19:25 ` Neal Cardwell
2019-12-16 19:30 ` Martin Lau
2019-12-17 8:26 ` Jakub Sitnicki
2019-12-17 18:22 ` Martin Lau
2019-12-17 21:04 ` Eric Dumazet
2019-12-18 9:03 ` Jakub Sitnicki
2019-12-16 19:14 ` Martin Lau
2019-12-16 19:33 ` Eric Dumazet
2019-12-16 21:17 ` Martin Lau
2019-12-16 23:08 ` Alexei Starovoitov
2019-12-17 0:34 ` Eric Dumazet
2019-12-14 0:48 ` [PATCH bpf-next 10/13] bpf: Synch uapi bpf.h to tools/ Martin KaFai Lau
2019-12-14 0:48 ` [PATCH bpf-next 11/13] bpf: libbpf: Add STRUCT_OPS support Martin KaFai Lau
2019-12-18 3:07 ` Andrii Nakryiko
2019-12-18 7:03 ` Martin Lau
2019-12-18 7:20 ` Martin Lau
2019-12-18 16:36 ` Andrii Nakryiko
2019-12-18 16:34 ` Andrii Nakryiko
2019-12-18 17:33 ` Martin Lau
2019-12-18 18:14 ` Andrii Nakryiko
2019-12-18 20:19 ` Martin Lau
2019-12-19 8:53 ` Toke Høiland-Jørgensen
2019-12-19 20:49 ` Andrii Nakryiko
2019-12-20 10:16 ` Toke Høiland-Jørgensen
2019-12-20 17:34 ` Andrii Nakryiko
2019-12-14 0:48 ` [PATCH bpf-next 12/13] bpf: Add bpf_dctcp example Martin KaFai Lau
2019-12-14 0:48 ` [PATCH bpf-next 13/13] bpf: Add bpf_cubic example Martin KaFai Lau
2019-12-14 2:26 ` [PATCH bpf-next 00/13] Introduce BPF STRUCT_OPS Eric Dumazet
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