netdev - Re: [PATCH v2] media: bpf: add bpf function to report mouse movement

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Message-ID: <4d72a8da-75c5-5050-6f85-c06694ad1b64@iogearbox.net>
Date:   Mon, 26 Nov 2018 01:55:36 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Sean Young <sean@...s.org>, Alexei Starovoitov <ast@...nel.org>,
        Roman Gushchin <guro@...com>, Martin KaFai Lau <kafai@...com>
Cc:     linux-media@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2] media: bpf: add bpf function to report mouse movement

Hi Sean,

On 11/23/2018 12:50 PM, Sean Young wrote:
> Some IR remotes have a directional pad or other pointer-like thing that
> can be used as a mouse. Make it possible to decode these types of IR
> protocols in BPF.
> 
> Cc: netdev@...r.kernel.org
> Signed-off-by: Sean Young <sean@...s.org>

Is this patch targeted at bpf-next tree?

> ---
>  drivers/media/rc/bpf-lirc.c               | 24 +++++++++++++++++++++++
>  include/uapi/linux/bpf.h                  | 17 +++++++++++++++-
>  tools/testing/selftests/bpf/bpf_helpers.h |  2 ++
>  3 files changed, 42 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/rc/bpf-lirc.c b/drivers/media/rc/bpf-lirc.c
> index 8b97fd1f0cea..390a722e6211 100644
> --- a/drivers/media/rc/bpf-lirc.c
> +++ b/drivers/media/rc/bpf-lirc.c
> @@ -59,6 +59,28 @@ static const struct bpf_func_proto rc_keydown_proto = {
>  	.arg4_type = ARG_ANYTHING,
>  };
>  
> +BPF_CALL_3(bpf_rc_pointer_rel, u32*, sample, s32, rel_x, s32, rel_y)
> +{
> +	struct ir_raw_event_ctrl *ctrl;
> +
> +	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
> +
> +	input_report_rel(ctrl->dev->input_dev, REL_X, rel_x);
> +	input_report_rel(ctrl->dev->input_dev, REL_Y, rel_y);
> +	input_sync(ctrl->dev->input_dev);
> +
> +	return 0;
> +}
> +
> +static const struct bpf_func_proto rc_pointer_rel_proto = {
> +	.func	   = bpf_rc_pointer_rel,
> +	.gpl_only  = true,
> +	.ret_type  = RET_INTEGER,
> +	.arg1_type = ARG_PTR_TO_CTX,
> +	.arg2_type = ARG_ANYTHING,
> +	.arg3_type = ARG_ANYTHING,
> +};
> +
>  static const struct bpf_func_proto *
>  lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>  {
> @@ -67,6 +89,8 @@ lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>  		return &rc_repeat_proto;
>  	case BPF_FUNC_rc_keydown:
>  		return &rc_keydown_proto;
> +	case BPF_FUNC_rc_pointer_rel:
> +		return &rc_pointer_rel_proto;
>  	case BPF_FUNC_map_lookup_elem:
>  		return &bpf_map_lookup_elem_proto;
>  	case BPF_FUNC_map_update_elem:
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 23e2031a43d4..3499a1555bbf 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -2268,6 +2268,20 @@ union bpf_attr {
>   *
>   *	Return
>   *		0 on success, or a negative error in case of failure.
> + *
> + * int bpf_rc_pointer_rel(void *ctx, s32 rel_x, s32 rel_y)
> + *	Description
> + *		This helper is used in programs implementing IR decoding, to
> + *		report a successfully decoded pointer movement.
> + *
> + *		The *ctx* should point to the lirc sample as passed into
> + *		the program.
> + *
> + *		This helper is only available is the kernel was compiled with
> + *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
> + *		"**y**".
> + *	Return
> + *		0
>   */
>  #define __BPF_FUNC_MAPPER(FN)		\
>  	FN(unspec),			\
> @@ -2360,7 +2374,8 @@ union bpf_attr {
>  	FN(map_push_elem),		\
>  	FN(map_pop_elem),		\
>  	FN(map_peek_elem),		\
> -	FN(msg_push_data),
> +	FN(msg_push_data),		\
> +	FN(rc_pointer_rel),
>  
>  /* integer value in 'imm' field of BPF_CALL instruction selects which helper
>   * function eBPF program intends to call
> diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
> index 686e57ce40f4..5c900a917fa4 100644
> --- a/tools/testing/selftests/bpf/bpf_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_helpers.h
> @@ -168,6 +168,8 @@ static int (*bpf_skb_vlan_push)(void *ctx, __be16 vlan_proto, __u16 vlan_tci) =
>  	(void *) BPF_FUNC_skb_vlan_push;
>  static int (*bpf_skb_vlan_pop)(void *ctx) =
>  	(void *) BPF_FUNC_skb_vlan_pop;
> +static int (*bpf_rc_pointer_rel)(void *ctx, int rel_x, int rel_y) =
> +	(void *) BPF_FUNC_rc_pointer_rel;
>  
>  /* llvm builtin functions that eBPF C program may use to
>   * emit BPF_LD_ABS and BPF_LD_IND instructions
> 

tools/include/uapi/linux/bpf.h would have to be synced as well here.

Probably would be good to extend the lirc2 BPF kselftest as well?

Thanks,
Daniel