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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Lawrence Brakmo <brakmo@fb.com>
Cc: netdev <netdev@vger.kernel.org>, Kernel Team <kernel-team@fb.com>,
	Blake Matheny <bmatheny@fb.com>, Alexei Starovoitov <ast@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Neal Cardwell <ncardwell@google.com>,
	Yuchung Cheng <ycheng@google.com>
Subject: Re: [PATCH bpf-next v6 03/11] bpf: Add write access to tcp_sock and sock fields
Date: Fri, 19 Jan 2018 19:54:45 -0800	[thread overview]
Message-ID: <20180120035443.sfm54gmdwfqw734s@ast-mbp> (raw)
In-Reply-To: <20180120014548.2941040-4-brakmo@fb.com>

On Fri, Jan 19, 2018 at 05:45:40PM -0800, Lawrence Brakmo wrote:
> This patch adds a macro, SOCK_OPS_SET_FIELD, for writing to
> struct tcp_sock or struct sock fields. This required adding a new
> field "temp" to struct bpf_sock_ops_kern for temporary storage that
> is used by sock_ops_convert_ctx_access. It is used to store and recover
> the contents of a register, so the register can be used to store the
> address of the sk. Since we cannot overwrite the dst_reg because it
> contains the pointer to ctx, nor the src_reg since it contains the value
> we want to store, we need an extra register to contain the address
> of the sk.
> 
> Also adds the macro SOCK_OPS_GET_OR_SET_FIELD that calls one of the
> GET or SET macros depending on the value of the TYPE field.
> 
> Signed-off-by: Lawrence Brakmo <brakmo@fb.com>

Acked-by: Alexei Starovoitov <ast@kernel.org>

that is really clever way of doing inline writes into fields.
I suspect we will be using this approach in other places.

  reply	other threads:[~2018-01-20  3:54 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-20  1:45 [PATCH bpf-next v6 00/11] bpf: More sock_ops callbacks Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 01/11] bpf: Make SOCK_OPS_GET_TCP size independent Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 02/11] bpf: Make SOCK_OPS_GET_TCP struct independent Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 03/11] bpf: Add write access to tcp_sock and sock fields Lawrence Brakmo
2018-01-20  3:54   ` Alexei Starovoitov [this message]
2018-01-20  1:45 ` [PATCH bpf-next v6 04/11] bpf: Support passing args to sock_ops bpf function Lawrence Brakmo
2018-01-24  1:11   ` Daniel Borkmann
2018-01-24  1:30     ` Lawrence Brakmo
2018-01-24  1:34       ` Daniel Borkmann
2018-01-20  1:45 ` [PATCH bpf-next v6 05/11] bpf: Adds field bpf_sock_ops_cb_flags to tcp_sock Lawrence Brakmo
2018-01-20  3:52   ` Alexei Starovoitov
2018-01-20  7:50     ` Lawrence Brakmo
2018-01-23 17:29     ` Eric Dumazet
2018-01-20  1:45 ` [PATCH bpf-next v6 06/11] bpf: Add sock_ops RTO callback Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 07/11] bpf: Add support for reading sk_state and more Lawrence Brakmo
2018-01-24  1:05   ` Daniel Borkmann
2018-01-24  1:27     ` Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 08/11] bpf: Add sock_ops R/W access to tclass & sk_txhash Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 09/11] bpf: Add BPF_SOCK_OPS_RETRANS_CB Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 10/11] bpf: Add BPF_SOCK_OPS_STATE_CB Lawrence Brakmo
2018-01-20  1:45 ` [PATCH bpf-next v6 11/11] bpf: add selftest for tcpbpf Lawrence Brakmo
2018-01-20  3:59   ` Alexei Starovoitov

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