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Subject[PATCH v1 1/4] media: rc: introduce BPF_PROG_IR_DECODER
Date
Add support for BPF_PROG_IR_DECODER. This type of BPF program can call
rc_keydown() to reported decoded IR scancodes, or rc_repeat() to report
that the last key should be repeated.

Signed-off-by: Sean Young <sean@mess.org>
---
drivers/media/rc/Kconfig | 8 +++
drivers/media/rc/Makefile | 1 +
drivers/media/rc/ir-bpf-decoder.c | 93 +++++++++++++++++++++++++++++++
include/linux/bpf_types.h | 3 +
include/uapi/linux/bpf.h | 16 +++++-
5 files changed, 120 insertions(+), 1 deletion(-)
create mode 100644 drivers/media/rc/ir-bpf-decoder.c

diff --git a/drivers/media/rc/Kconfig b/drivers/media/rc/Kconfig
index eb2c3b6eca7f..10ad6167d87c 100644
--- a/drivers/media/rc/Kconfig
+++ b/drivers/media/rc/Kconfig
@@ -120,6 +120,14 @@ config IR_IMON_DECODER
remote control and you would like to use it with a raw IR
receiver, or if you wish to use an encoder to transmit this IR.

+config IR_BPF_DECODER
+ bool "Enable IR raw decoder using BPF"
+ depends on BPF_SYSCALL
+ depends on RC_CORE=y
+ help
+ Enable this option to make it possible to load custom IR
+ decoders written in BPF.
+
endif #RC_DECODERS

menuconfig RC_DEVICES
diff --git a/drivers/media/rc/Makefile b/drivers/media/rc/Makefile
index 2e1c87066f6c..12e1118430d0 100644
--- a/drivers/media/rc/Makefile
+++ b/drivers/media/rc/Makefile
@@ -5,6 +5,7 @@ obj-y += keymaps/
obj-$(CONFIG_RC_CORE) += rc-core.o
rc-core-y := rc-main.o rc-ir-raw.o
rc-core-$(CONFIG_LIRC) += lirc_dev.o
+rc-core-$(CONFIG_IR_BPF_DECODER) += ir-bpf-decoder.o
obj-$(CONFIG_IR_NEC_DECODER) += ir-nec-decoder.o
obj-$(CONFIG_IR_RC5_DECODER) += ir-rc5-decoder.o
obj-$(CONFIG_IR_RC6_DECODER) += ir-rc6-decoder.o
diff --git a/drivers/media/rc/ir-bpf-decoder.c b/drivers/media/rc/ir-bpf-decoder.c
new file mode 100644
index 000000000000..aaa5e208b1a5
--- /dev/null
+++ b/drivers/media/rc/ir-bpf-decoder.c
@@ -0,0 +1,93 @@
+// SPDX-License-Identifier: GPL-2.0
+// ir-bpf-decoder.c - handles bpf decoders
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include "rc-core-priv.h"
+
+/*
+ * BPF interface for raw IR decoder
+ */
+const struct bpf_prog_ops ir_decoder_prog_ops = {
+};
+
+BPF_CALL_1(bpf_rc_repeat, struct ir_raw_event*, event)
+{
+ struct ir_raw_event_ctrl *ctrl;
+
+ ctrl = container_of(event, struct ir_raw_event_ctrl, prev_ev);
+
+ rc_repeat(ctrl->dev);
+ return 0;
+}
+
+static const struct bpf_func_proto rc_repeat_proto = {
+ .func = bpf_rc_repeat,
+ .gpl_only = true, // rc_repeat is EXPORT_SYMBOL_GPL
+ .ret_type = RET_VOID,
+ .arg1_type = ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_4(bpf_rc_keydown, struct ir_raw_event*, event, u32, protocol,
+ u32, scancode, u32, toggle)
+{
+ struct ir_raw_event_ctrl *ctrl;
+
+ ctrl = container_of(event, struct ir_raw_event_ctrl, prev_ev);
+ rc_keydown(ctrl->dev, protocol, scancode, toggle != 0);
+ return 0;
+}
+
+static const struct bpf_func_proto rc_keydown_proto = {
+ .func = bpf_rc_keydown,
+ .gpl_only = true, // rc_keydown is EXPORT_SYMBOL_GPL
+ .ret_type = RET_VOID,
+ .arg1_type = ARG_PTR_TO_CTX,
+ .arg2_type = ARG_ANYTHING,
+ .arg3_type = ARG_ANYTHING,
+ .arg4_type = ARG_ANYTHING,
+};
+
+static const struct bpf_func_proto *ir_decoder_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
+{
+ switch (func_id) {
+ case BPF_FUNC_rc_repeat:
+ return &rc_repeat_proto;
+ case BPF_FUNC_rc_keydown:
+ return &rc_keydown_proto;
+ case BPF_FUNC_map_lookup_elem:
+ return &bpf_map_lookup_elem_proto;
+ case BPF_FUNC_map_update_elem:
+ return &bpf_map_update_elem_proto;
+ case BPF_FUNC_map_delete_elem:
+ return &bpf_map_delete_elem_proto;
+ case BPF_FUNC_ktime_get_ns:
+ return &bpf_ktime_get_ns_proto;
+ case BPF_FUNC_tail_call:
+ return &bpf_tail_call_proto;
+ case BPF_FUNC_get_prandom_u32:
+ return &bpf_get_prandom_u32_proto;
+ default:
+ return NULL;
+ }
+}
+
+static bool ir_decoder_is_valid_access(int off, int size,
+ enum bpf_access_type type,
+ const struct bpf_prog *prog,
+ struct bpf_insn_access_aux *info)
+{
+ if (type == BPF_WRITE)
+ return false;
+ if (off < 0 || off + size > sizeof(struct ir_raw_event))
+ return false;
+
+ return true;
+}
+
+const struct bpf_verifier_ops ir_decoder_verifier_ops = {
+ .get_func_proto = ir_decoder_func_proto,
+ .is_valid_access = ir_decoder_is_valid_access
+};
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 2b28fcf6f6ae..ee5355715ee0 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -25,6 +25,9 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_RAW_TRACEPOINT, raw_tracepoint)
#ifdef CONFIG_CGROUP_BPF
BPF_PROG_TYPE(BPF_PROG_TYPE_CGROUP_DEVICE, cg_dev)
#endif
+#ifdef CONFIG_IR_BPF_DECODER
+BPF_PROG_TYPE(BPF_PROG_TYPE_RAWIR_DECODER, ir_decoder)
+#endif

BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c5ec89732a8d..6ad053e831c0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -137,6 +137,7 @@ enum bpf_prog_type {
BPF_PROG_TYPE_SK_MSG,
BPF_PROG_TYPE_RAW_TRACEPOINT,
BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+ BPF_PROG_TYPE_RAWIR_DECODER,
};

enum bpf_attach_type {
@@ -755,6 +756,17 @@ union bpf_attr {
* @addr: pointer to struct sockaddr to bind socket to
* @addr_len: length of sockaddr structure
* Return: 0 on success or negative error code
+ *
+ * int bpf_rc_keydown(ctx, protocol, scancode, toggle)
+ * Report decoded scancode with toggle value
+ * @ctx: pointer to ctx
+ * @protocol: decoded protocol
+ * @scancode: decoded scancode
+ * @toggle: set to 1 if button was toggled, else 0
+ *
+ * int bpf_rc_repeat(ctx)
+ * Repeat the last decoded scancode
+ * @ctx: pointer to ctx
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -821,7 +833,9 @@ union bpf_attr {
FN(msg_apply_bytes), \
FN(msg_cork_bytes), \
FN(msg_pull_data), \
- FN(bind),
+ FN(bind), \
+ FN(rc_repeat), \
+ FN(rc_keydown),

/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
--
2.17.0
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