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

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Message-Id: <20181123115040.13725-1-sean@mess.org>
Date:   Fri, 23 Nov 2018 11:50:40 +0000
From:   Sean Young <sean@...s.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Roman Gushchin <guro@...com>, Martin KaFai Lau <kafai@...com>
Cc:     linux-media@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH v2] media: bpf: add bpf function to report mouse movement

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>
---
 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
-- 
2.19.1