[PATCH v2 0/2] IR decoding using BPF

[PATCH v2 0/2] IR decoding using BPF

[Sean Young]

The kernel IR decoders support the most widely used IR protocols, but there
are many protocols which are not supported[1]. For example, the
lirc-remotes[2] repo has over 2700 remotes, many of which are not supported
by rc-core. There is a "long tail" of unsupported IR protocols.

IR encoding is done in such a way that some simple circuit can decode it;
therefore, bpf is ideal.

In order to support all these protocols, here we have bpf based IR decoding.
The idea is that user-space can define a decoder in bpf, attach it to
the rc device through the lirc chardev.

Separate work is underway to extend ir-keytable to have an extensive library
of bpf-based decoders, and a much expanded library of rc keymaps.

Another future application would be to compile IRP[3] to a IR BPF program, and
so support virtually every remote without having to write a decoder for each.

Thanks,

Sean Young

[1] http://www.hifi-remote.com/wiki/index.php?title=DecodeIR
[2] https://sourceforge.net/p/lirc-remotes/code/ci/master/tree/remotes/
[3] http://www.hifi-remote.com/wiki/index.php?title=IRP_Notation

Changes since v1:
 - Code review comments from Y Song <ys114321@gmail.com> and
   Randy Dunlap <rdunlap@infradead.org>
 - Re-wrote sample bpf to be selftest
 - Renamed RAWIR_DECODER -> RAWIR_EVENT (Kconfig, context, bpf prog type)
 - Rebase on bpf-next
 - Introduced bpf_rawir_event context structure with simpler access checking

Sean Young (2):
  media: rc: introduce BPF_PROG_RAWIR_EVENT
  bpf: add selftest for rawir_event type program

 drivers/media/rc/Kconfig                      |  10 +
 drivers/media/rc/Makefile                     |   1 +
 drivers/media/rc/bpf-rawir-event.c            | 322 ++++++++++++++++++
 drivers/media/rc/lirc_dev.c                   |  28 ++
 drivers/media/rc/rc-core-priv.h               |  19 ++
 drivers/media/rc/rc-ir-raw.c                  |   3 +
 include/linux/bpf_rcdev.h                     |  30 ++
 include/linux/bpf_types.h                     |   3 +
 include/uapi/linux/bpf.h                      |  55 ++-
 kernel/bpf/syscall.c                          |   7 +
 tools/bpf/bpftool/prog.c                      |   1 +
 tools/include/uapi/linux/bpf.h                |  55 ++-
 tools/lib/bpf/libbpf.c                        |   1 +
 tools/testing/selftests/bpf/Makefile          |   7 +-
 tools/testing/selftests/bpf/bpf_helpers.h     |   6 +
 tools/testing/selftests/bpf/test_rawir.sh     |  37 ++
 .../selftests/bpf/test_rawir_event_kern.c     |  26 ++
 .../selftests/bpf/test_rawir_event_user.c     |  90 +++++
 18 files changed, 696 insertions(+), 5 deletions(-)
 create mode 100644 drivers/media/rc/bpf-rawir-event.c
 create mode 100644 include/linux/bpf_rcdev.h
 create mode 100755 tools/testing/selftests/bpf/test_rawir.sh
 create mode 100644 tools/testing/selftests/bpf/test_rawir_event_kern.c
 create mode 100644 tools/testing/selftests/bpf/test_rawir_event_user.c

-- 
2.17.0

[PATCH v2 1/2] media: rc: introduce BPF_PROG_RAWIR_EVENT

[Sean Young]

Add support for BPF_PROG_RAWIR_EVENT. 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.

The bpf program can be attached to using the bpf(BPF_PROG_ATTACH) syscall;
the target_fd must be the /dev/lircN device.

Signed-off-by: Sean Young <sean@mess.org>
---
 drivers/media/rc/Kconfig           |  10 +
 drivers/media/rc/Makefile          |   1 +
 drivers/media/rc/bpf-rawir-event.c | 322 +++++++++++++++++++++++++++++
 drivers/media/rc/lirc_dev.c        |  28 +++
 drivers/media/rc/rc-core-priv.h    |  19 ++
 drivers/media/rc/rc-ir-raw.c       |   3 +
 include/linux/bpf_rcdev.h          |  30 +++
 include/linux/bpf_types.h          |   3 +
 include/uapi/linux/bpf.h           |  55 ++++-
 kernel/bpf/syscall.c               |   7 +
 10 files changed, 477 insertions(+), 1 deletion(-)
 create mode 100644 drivers/media/rc/bpf-rawir-event.c
 create mode 100644 include/linux/bpf_rcdev.h

diff --git a/drivers/media/rc/Kconfig b/drivers/media/rc/Kconfig
index eb2c3b6eca7f..55747af5b978 100644
--- a/drivers/media/rc/Kconfig
+++ b/drivers/media/rc/Kconfig
@@ -25,6 +25,16 @@ config LIRC
 	   passes raw IR to and from userspace, which is needed for
 	   IR transmitting (aka "blasting") and for the lirc daemon.
 
+config BPF_RAWIR_EVENT
+	bool "Enable attaching BPF programs to lirc devices"
+	depends on BPF_SYSCALL
+	depends on RC_CORE=y
+	depends on LIRC
+	help
+	   Enable this option to make it possible to load custom IR
+	   decoders written in BPF. These decoders are type
+	   BPF_PROG_TYPE_RAW_IR_EVENT.
+
 menuconfig RC_DECODERS
 	bool "Remote controller decoders"
 	depends on RC_CORE
diff --git a/drivers/media/rc/Makefile b/drivers/media/rc/Makefile
index 2e1c87066f6c..74907823bef8 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-$(CONFIG_BPF_RAWIR_EVENT) += bpf-rawir-event.o
 obj-$(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/bpf-rawir-event.c b/drivers/media/rc/bpf-rawir-event.c
new file mode 100644
index 000000000000..8007841977d6
--- /dev/null
+++ b/drivers/media/rc/bpf-rawir-event.c
@@ -0,0 +1,322 @@
+// SPDX-License-Identifier: GPL-2.0
+// bpf-rawir-event.c - handles bpf
+//
+// 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
+ */
+const struct bpf_prog_ops rawir_event_prog_ops = {
+};
+
+BPF_CALL_1(bpf_rc_repeat, struct bpf_rawir_event*, event)
+{
+	struct ir_raw_event_ctrl *ctrl;
+
+	ctrl = container_of(event, struct ir_raw_event_ctrl, bpf_rawir_event);
+
+	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_INTEGER,
+	.arg1_type = ARG_PTR_TO_CTX,
+};
+
+BPF_CALL_4(bpf_rc_keydown, struct bpf_rawir_event*, event, u32, protocol,
+	   u32, scancode, u32, toggle)
+{
+	struct ir_raw_event_ctrl *ctrl;
+
+	ctrl = container_of(event, struct ir_raw_event_ctrl, bpf_rawir_event);
+
+	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_INTEGER,
+	.arg1_type = ARG_PTR_TO_CTX,
+	.arg2_type = ARG_ANYTHING,
+	.arg3_type = ARG_ANYTHING,
+	.arg4_type = ARG_ANYTHING,
+};
+
+static const struct bpf_func_proto *
+rawir_event_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 rawir_event_is_valid_access(int off, int size,
+					enum bpf_access_type type,
+					const struct bpf_prog *prog,
+					struct bpf_insn_access_aux *info)
+{
+	/* struct bpf_rawir_event has two u32 fields */
+	if (type == BPF_WRITE)
+		return false;
+
+	if (size != sizeof(__u32))
+		return false;
+
+	if (!(off == offsetof(struct bpf_rawir_event, duration) ||
+	      off == offsetof(struct bpf_rawir_event, type)))
+		return false;
+
+	return true;
+}
+
+const struct bpf_verifier_ops rawir_event_verifier_ops = {
+	.get_func_proto  = rawir_event_func_proto,
+	.is_valid_access = rawir_event_is_valid_access
+};
+
+#define BPF_MAX_PROGS 64
+
+static int rc_dev_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
+{
+	struct ir_raw_event_ctrl *raw;
+	struct bpf_prog_array __rcu *old_array;
+	struct bpf_prog_array *new_array;
+	int ret, i, size;
+
+	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
+		return -EINVAL;
+
+	ret = mutex_lock_interruptible(&rcdev->lock);
+	if (ret)
+		return ret;
+
+	raw = rcdev->raw;
+
+	if (raw->progs) {
+		size = bpf_prog_array_length(raw->progs);
+		for (i = 0; i < size; i++) {
+			if (prog == raw->progs->progs[i]) {
+				ret = -EEXIST;
+				goto out;
+			}
+		}
+
+		if (size >= BPF_MAX_PROGS) {
+			ret = -E2BIG;
+			goto out;
+		}
+	}
+
+	old_array = raw->progs;
+	ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
+	if (ret < 0)
+		goto out;
+
+	rcu_assign_pointer(raw->progs, new_array);
+	bpf_prog_array_free(old_array);
+out:
+	mutex_unlock(&rcdev->lock);
+	return ret;
+}
+
+static int rc_dev_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
+{
+	struct ir_raw_event_ctrl *raw;
+	struct bpf_prog_array __rcu *old_array;
+	struct bpf_prog_array *new_array;
+	int ret;
+
+	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
+		return -EINVAL;
+
+	ret = mutex_lock_interruptible(&rcdev->lock);
+	if (ret)
+		return ret;
+
+	raw = rcdev->raw;
+
+	old_array = raw->progs;
+	ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
+	if (ret < 0) {
+		bpf_prog_array_delete_safe(old_array, prog);
+	} else {
+		rcu_assign_pointer(raw->progs, new_array);
+		bpf_prog_array_free(old_array);
+	}
+
+	bpf_prog_put(prog);
+	mutex_unlock(&rcdev->lock);
+	return 0;
+}
+
+void rc_dev_bpf_run(struct rc_dev *rcdev, struct ir_raw_event ev)
+{
+	struct ir_raw_event_ctrl *raw = rcdev->raw;
+
+	if (!raw->progs)
+		return;
+
+	if (unlikely(ev.carrier_report)) {
+		raw->bpf_rawir_event.carrier = ev.carrier;
+		raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_CARRIER;
+	} else {
+		raw->bpf_rawir_event.duration = ev.duration;
+
+		if (ev.pulse)
+			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_PULSE;
+		else if (ev.timeout)
+			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_TIMEOUT;
+		else if (ev.reset)
+			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_RESET;
+		else
+			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_SPACE;
+	}
+
+	BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_rawir_event, BPF_PROG_RUN);
+}
+
+void rc_dev_bpf_put(struct rc_dev *rcdev)
+{
+	struct bpf_prog_array *progs = rcdev->raw->progs;
+	int i, size;
+
+	if (!progs)
+		return;
+
+	size = bpf_prog_array_length(progs);
+	for (i = 0; i < size; i++)
+		bpf_prog_put(progs->progs[i]);
+
+	bpf_prog_array_free(rcdev->raw->progs);
+}
+
+int rc_dev_prog_attach(const union bpf_attr *attr)
+{
+	struct bpf_prog *prog;
+	struct rc_dev *rcdev;
+	int ret;
+
+	if (attr->attach_flags)
+		return -EINVAL;
+
+	prog = bpf_prog_get_type(attr->attach_bpf_fd,
+				 BPF_PROG_TYPE_RAWIR_EVENT);
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
+
+	rcdev = rc_dev_get_from_fd(attr->target_fd);
+	if (IS_ERR(rcdev)) {
+		bpf_prog_put(prog);
+		return PTR_ERR(rcdev);
+	}
+
+	ret = rc_dev_bpf_attach(rcdev, prog);
+	if (ret)
+		bpf_prog_put(prog);
+
+	put_device(&rcdev->dev);
+
+	return ret;
+}
+
+int rc_dev_prog_detach(const union bpf_attr *attr)
+{
+	struct bpf_prog *prog;
+	struct rc_dev *rcdev;
+	int ret;
+
+	if (attr->attach_flags)
+		return -EINVAL;
+
+	prog = bpf_prog_get_type(attr->attach_bpf_fd,
+				 BPF_PROG_TYPE_RAWIR_EVENT);
+	if (IS_ERR(prog))
+		return PTR_ERR(prog);
+
+	rcdev = rc_dev_get_from_fd(attr->target_fd);
+	if (IS_ERR(rcdev)) {
+		bpf_prog_put(prog);
+		return PTR_ERR(rcdev);
+	}
+
+	ret = rc_dev_bpf_detach(rcdev, prog);
+
+	bpf_prog_put(prog);
+	put_device(&rcdev->dev);
+
+	return ret;
+}
+
+int rc_dev_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
+{
+	__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
+	struct bpf_prog_array *progs;
+	struct rc_dev *rcdev;
+	u32 cnt, flags = 0;
+	int ret;
+
+	if (attr->query.query_flags)
+		return -EINVAL;
+
+	rcdev = rc_dev_get_from_fd(attr->query.target_fd);
+	if (IS_ERR(rcdev))
+		return PTR_ERR(rcdev);
+
+	if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = mutex_lock_interruptible(&rcdev->lock);
+	if (ret)
+		goto out;
+
+	progs = rcdev->raw->progs;
+	cnt = progs ? bpf_prog_array_length(progs) : 0;
+
+	if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
+		ret = -EFAULT;
+		goto out;
+	}
+	if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
+		ret = -EFAULT;
+		goto out;
+	}
+
+	if (attr->query.prog_cnt != 0 && prog_ids && cnt)
+		ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
+
+out:
+	mutex_unlock(&rcdev->lock);
+	put_device(&rcdev->dev);
+
+	return ret;
+}
diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
index 24e9fbb80e81..c3028d0366d1 100644
--- a/drivers/media/rc/lirc_dev.c
+++ b/drivers/media/rc/lirc_dev.c
@@ -20,6 +20,7 @@
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/device.h>
+#include <linux/file.h>
 #include <linux/idr.h>
 #include <linux/poll.h>
 #include <linux/sched.h>
@@ -816,4 +817,31 @@ void __exit lirc_dev_exit(void)
 	unregister_chrdev_region(lirc_base_dev, RC_DEV_MAX);
 }
 
+struct rc_dev *rc_dev_get_from_fd(int fd)
+{
+	struct rc_dev *dev;
+	struct file *f;
+
+	f = fget_raw(fd);
+	if (!f)
+		return ERR_PTR(-EBADF);
+
+	if (!S_ISCHR(f->f_inode->i_mode) ||
+	    imajor(f->f_inode) != MAJOR(lirc_base_dev)) {
+		fput(f);
+		return ERR_PTR(-EBADF);
+	}
+
+	dev = container_of(f->f_inode->i_cdev, struct rc_dev, lirc_cdev);
+	if (!dev->registered) {
+		fput(f);
+		return ERR_PTR(-ENODEV);
+	}
+
+	get_device(&dev->dev);
+	fput(f);
+
+	return dev;
+}
+
 MODULE_ALIAS("lirc_dev");
diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index e0e6a17460f6..6db579f425f1 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -13,6 +13,7 @@
 #define	MAX_IR_EVENT_SIZE	512
 
 #include <linux/slab.h>
+#include <uapi/linux/bpf.h>
 #include <media/rc-core.h>
 
 /**
@@ -57,6 +58,11 @@ struct ir_raw_event_ctrl {
 	/* raw decoder state follows */
 	struct ir_raw_event prev_ev;
 	struct ir_raw_event this_ev;
+
+#ifdef CONFIG_BPF_RAWIR_EVENT
+	struct bpf_rawir_event		bpf_rawir_event;
+	struct bpf_prog_array		*progs;
+#endif
 	struct nec_dec {
 		int state;
 		unsigned count;
@@ -288,6 +294,7 @@ void ir_lirc_raw_event(struct rc_dev *dev, struct ir_raw_event ev);
 void ir_lirc_scancode_event(struct rc_dev *dev, struct lirc_scancode *lsc);
 int ir_lirc_register(struct rc_dev *dev);
 void ir_lirc_unregister(struct rc_dev *dev);
+struct rc_dev *rc_dev_get_from_fd(int fd);
 #else
 static inline int lirc_dev_init(void) { return 0; }
 static inline void lirc_dev_exit(void) {}
@@ -299,4 +306,16 @@ static inline int ir_lirc_register(struct rc_dev *dev) { return 0; }
 static inline void ir_lirc_unregister(struct rc_dev *dev) { }
 #endif
 
+/*
+ * bpf interface
+ */
+#ifdef CONFIG_BPF_RAWIR_EVENT
+void rc_dev_bpf_put(struct rc_dev *dev);
+void rc_dev_bpf_run(struct rc_dev *dev, struct ir_raw_event ev);
+#else
+static inline void rc_dev_bpf_put(struct rc_dev *dev) { }
+static inline void rc_dev_bpf_run(struct rc_dev *dev, struct ir_raw_event ev)
+{ }
+#endif
+
 #endif /* _RC_CORE_PRIV */
diff --git a/drivers/media/rc/rc-ir-raw.c b/drivers/media/rc/rc-ir-raw.c
index 374f83105a23..25828f15faec 100644
--- a/drivers/media/rc/rc-ir-raw.c
+++ b/drivers/media/rc/rc-ir-raw.c
@@ -32,6 +32,7 @@ static int ir_raw_event_thread(void *data)
 				    handler->protocols || !handler->protocols)
 					handler->decode(raw->dev, ev);
 			ir_lirc_raw_event(raw->dev, ev);
+			rc_dev_bpf_run(raw->dev, ev);
 			raw->prev_ev = ev;
 		}
 		mutex_unlock(&ir_raw_handler_lock);
@@ -623,6 +624,8 @@ void ir_raw_event_unregister(struct rc_dev *dev)
 			handler->raw_unregister(dev);
 	mutex_unlock(&ir_raw_handler_lock);
 
+	rc_dev_bpf_put(dev);
+
 	ir_raw_event_free(dev);
 }
 
diff --git a/include/linux/bpf_rcdev.h b/include/linux/bpf_rcdev.h
new file mode 100644
index 000000000000..17a30f30436a
--- /dev/null
+++ b/include/linux/bpf_rcdev.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BPF_RCDEV_H
+#define _BPF_RCDEV_H
+
+#include <linux/bpf.h>
+#include <uapi/linux/bpf.h>
+
+#ifdef CONFIG_BPF_RAWIR_EVENT
+int rc_dev_prog_attach(const union bpf_attr *attr);
+int rc_dev_prog_detach(const union bpf_attr *attr);
+int rc_dev_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr);
+#else
+static inline int rc_dev_prog_attach(const union bpf_attr *attr)
+{
+	return -EINVAL;
+}
+
+static inline int rc_dev_prog_detach(const union bpf_attr *attr)
+{
+	return -EINVAL;
+}
+
+static inline int rc_dev_prog_query(const union bpf_attr *attr,
+				    union bpf_attr __user *uattr)
+{
+	return -EINVAL;
+}
+#endif
+
+#endif /* _BPF_RCDEV_H */
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index d7df1b323082..667d1d557090 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_BPF_RAWIR_EVENT
+BPF_PROG_TYPE(BPF_PROG_TYPE_RAWIR_EVENT, rawir_event)
+#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 02e4112510f8..8ba1be825af0 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -140,6 +140,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_SK_MSG,
 	BPF_PROG_TYPE_RAW_TRACEPOINT,
 	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+	BPF_PROG_TYPE_RAWIR_EVENT,
 };
 
 enum bpf_attach_type {
@@ -157,6 +158,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_CONNECT,
 	BPF_CGROUP_INET4_POST_BIND,
 	BPF_CGROUP_INET6_POST_BIND,
+	BPF_RAWIR_EVENT,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -1855,6 +1857,35 @@ union bpf_attr {
  *             Egress device index on success, 0 if packet needs to continue
  *             up the stack for further processing or a negative error in case
  *             of failure.
+ *
+ * int bpf_rc_keydown(void *ctx, u32 protocol, u32 scancode, u32 toggle)
+ *	Description
+ *		Report decoded scancode with toggle value. For use in
+ *		BPF_PROG_TYPE_RAWIR_EVENT, to report a successfully
+ *		decoded scancode. This is will generate a keydown event,
+ *		and a keyup event once the scancode is no longer repeated.
+ *
+ *		*ctx* pointer to bpf_rawir_event, *protocol* is decoded
+ *		protocol (see RC_PROTO_* enum).
+ *
+ *		Some protocols include a toggle bit, in case the button
+ *		was released and pressed again between consecutive scancodes,
+ *		copy this bit into *toggle* if it exists, else set to 0.
+ *
+ *     Return
+ *		Always return 0 (for now)
+ *
+ * int bpf_rc_repeat(void *ctx)
+ *	Description
+ *		Repeat the last decoded scancode; some IR protocols like
+ *		NEC have a special IR message for repeat last button,
+ *		in case user is holding a button down; the scancode is
+ *		not repeated.
+ *
+ *		*ctx* pointer to bpf_rawir_event.
+ *
+ *     Return
+ *		Always return 0 (for now)
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -1926,7 +1957,9 @@ union bpf_attr {
 	FN(skb_get_xfrm_state),		\
 	FN(get_stack),			\
 	FN(skb_load_bytes_relative),	\
-	FN(fib_lookup),
+	FN(fib_lookup),			\
+	FN(rc_repeat),			\
+	FN(rc_keydown),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -1993,6 +2026,26 @@ enum bpf_hdr_start_off {
 	BPF_HDR_START_NET,
 };
 
+/*
+ * user accessible mirror of in-kernel ir_raw_event
+ */
+#define BPF_RAWIR_EVENT_SPACE		0
+#define BPF_RAWIR_EVENT_PULSE		1
+#define BPF_RAWIR_EVENT_TIMEOUT		2
+#define BPF_RAWIR_EVENT_RESET		3
+#define BPF_RAWIR_EVENT_CARRIER		4
+#define BPF_RAWIR_EVENT_DUTY_CYCLE	5
+
+struct bpf_rawir_event {
+	union {
+		__u32	duration;
+		__u32	carrier;
+		__u32	duty_cycle;
+	};
+
+	__u32	type;
+};
+
 /* user accessible mirror of in-kernel sk_buff.
  * new fields can only be added to the end of this structure
  */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e2aeb5e89f44..75c089f407c8 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -11,6 +11,7 @@
  */
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
+#include <linux/bpf_rcdev.h>
 #include <linux/btf.h>
 #include <linux/syscalls.h>
 #include <linux/slab.h>
@@ -1567,6 +1568,8 @@ static int bpf_prog_attach(const union bpf_attr *attr)
 	case BPF_SK_SKB_STREAM_PARSER:
 	case BPF_SK_SKB_STREAM_VERDICT:
 		return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, true);
+	case BPF_RAWIR_EVENT:
+		return rc_dev_prog_attach(attr);
 	default:
 		return -EINVAL;
 	}
@@ -1637,6 +1640,8 @@ static int bpf_prog_detach(const union bpf_attr *attr)
 	case BPF_SK_SKB_STREAM_PARSER:
 	case BPF_SK_SKB_STREAM_VERDICT:
 		return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, false);
+	case BPF_RAWIR_EVENT:
+		return rc_dev_prog_detach(attr);
 	default:
 		return -EINVAL;
 	}
@@ -1684,6 +1689,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
 	case BPF_CGROUP_SOCK_OPS:
 	case BPF_CGROUP_DEVICE:
 		break;
+	case BPF_RAWIR_EVENT:
+		return rc_dev_prog_query(attr, uattr);
 	default:
 		return -EINVAL;
 	}
-- 
2.17.0

Re: [PATCH v2 1/2] media: rc: introduce BPF_PROG_RAWIR_EVENT

[Sean Young]

On Tue, May 15, 2018 at 07:50:19PM +0100, Sean Young wrote:
> Add support for BPF_PROG_RAWIR_EVENT. 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.
> 
> The bpf program can be attached to using the bpf(BPF_PROG_ATTACH) syscall;
> the target_fd must be the /dev/lircN device.

The locking of the list of attached bpf programs is broken in various ways.
I'll have to rework this for v3.


Sean

> 
> Signed-off-by: Sean Young <sean@mess.org>
> ---
>  drivers/media/rc/Kconfig           |  10 +
>  drivers/media/rc/Makefile          |   1 +
>  drivers/media/rc/bpf-rawir-event.c | 322 +++++++++++++++++++++++++++++
>  drivers/media/rc/lirc_dev.c        |  28 +++
>  drivers/media/rc/rc-core-priv.h    |  19 ++
>  drivers/media/rc/rc-ir-raw.c       |   3 +
>  include/linux/bpf_rcdev.h          |  30 +++
>  include/linux/bpf_types.h          |   3 +
>  include/uapi/linux/bpf.h           |  55 ++++-
>  kernel/bpf/syscall.c               |   7 +
>  10 files changed, 477 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/media/rc/bpf-rawir-event.c
>  create mode 100644 include/linux/bpf_rcdev.h
> 
> diff --git a/drivers/media/rc/Kconfig b/drivers/media/rc/Kconfig
> index eb2c3b6eca7f..55747af5b978 100644
> --- a/drivers/media/rc/Kconfig
> +++ b/drivers/media/rc/Kconfig
> @@ -25,6 +25,16 @@ config LIRC
>  	   passes raw IR to and from userspace, which is needed for
>  	   IR transmitting (aka "blasting") and for the lirc daemon.
>  
> +config BPF_RAWIR_EVENT
> +	bool "Enable attaching BPF programs to lirc devices"
> +	depends on BPF_SYSCALL
> +	depends on RC_CORE=y
> +	depends on LIRC
> +	help
> +	   Enable this option to make it possible to load custom IR
> +	   decoders written in BPF. These decoders are type
> +	   BPF_PROG_TYPE_RAW_IR_EVENT.
> +
>  menuconfig RC_DECODERS
>  	bool "Remote controller decoders"
>  	depends on RC_CORE
> diff --git a/drivers/media/rc/Makefile b/drivers/media/rc/Makefile
> index 2e1c87066f6c..74907823bef8 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-$(CONFIG_BPF_RAWIR_EVENT) += bpf-rawir-event.o
>  obj-$(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/bpf-rawir-event.c b/drivers/media/rc/bpf-rawir-event.c
> new file mode 100644
> index 000000000000..8007841977d6
> --- /dev/null
> +++ b/drivers/media/rc/bpf-rawir-event.c
> @@ -0,0 +1,322 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// bpf-rawir-event.c - handles bpf
> +//
> +// 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
> + */
> +const struct bpf_prog_ops rawir_event_prog_ops = {
> +};
> +
> +BPF_CALL_1(bpf_rc_repeat, struct bpf_rawir_event*, event)
> +{
> +	struct ir_raw_event_ctrl *ctrl;
> +
> +	ctrl = container_of(event, struct ir_raw_event_ctrl, bpf_rawir_event);
> +
> +	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_INTEGER,
> +	.arg1_type = ARG_PTR_TO_CTX,
> +};
> +
> +BPF_CALL_4(bpf_rc_keydown, struct bpf_rawir_event*, event, u32, protocol,
> +	   u32, scancode, u32, toggle)
> +{
> +	struct ir_raw_event_ctrl *ctrl;
> +
> +	ctrl = container_of(event, struct ir_raw_event_ctrl, bpf_rawir_event);
> +
> +	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_INTEGER,
> +	.arg1_type = ARG_PTR_TO_CTX,
> +	.arg2_type = ARG_ANYTHING,
> +	.arg3_type = ARG_ANYTHING,
> +	.arg4_type = ARG_ANYTHING,
> +};
> +
> +static const struct bpf_func_proto *
> +rawir_event_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 rawir_event_is_valid_access(int off, int size,
> +					enum bpf_access_type type,
> +					const struct bpf_prog *prog,
> +					struct bpf_insn_access_aux *info)
> +{
> +	/* struct bpf_rawir_event has two u32 fields */
> +	if (type == BPF_WRITE)
> +		return false;
> +
> +	if (size != sizeof(__u32))
> +		return false;
> +
> +	if (!(off == offsetof(struct bpf_rawir_event, duration) ||
> +	      off == offsetof(struct bpf_rawir_event, type)))
> +		return false;
> +
> +	return true;
> +}
> +
> +const struct bpf_verifier_ops rawir_event_verifier_ops = {
> +	.get_func_proto  = rawir_event_func_proto,
> +	.is_valid_access = rawir_event_is_valid_access
> +};
> +
> +#define BPF_MAX_PROGS 64
> +
> +static int rc_dev_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
> +{
> +	struct ir_raw_event_ctrl *raw;
> +	struct bpf_prog_array __rcu *old_array;
> +	struct bpf_prog_array *new_array;
> +	int ret, i, size;
> +
> +	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
> +		return -EINVAL;
> +
> +	ret = mutex_lock_interruptible(&rcdev->lock);
> +	if (ret)
> +		return ret;
> +
> +	raw = rcdev->raw;
> +
> +	if (raw->progs) {
> +		size = bpf_prog_array_length(raw->progs);
> +		for (i = 0; i < size; i++) {
> +			if (prog == raw->progs->progs[i]) {
> +				ret = -EEXIST;
> +				goto out;
> +			}
> +		}
> +
> +		if (size >= BPF_MAX_PROGS) {
> +			ret = -E2BIG;
> +			goto out;
> +		}
> +	}
> +
> +	old_array = raw->progs;
> +	ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
> +	if (ret < 0)
> +		goto out;
> +
> +	rcu_assign_pointer(raw->progs, new_array);
> +	bpf_prog_array_free(old_array);
> +out:
> +	mutex_unlock(&rcdev->lock);
> +	return ret;
> +}
> +
> +static int rc_dev_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
> +{
> +	struct ir_raw_event_ctrl *raw;
> +	struct bpf_prog_array __rcu *old_array;
> +	struct bpf_prog_array *new_array;
> +	int ret;
> +
> +	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
> +		return -EINVAL;
> +
> +	ret = mutex_lock_interruptible(&rcdev->lock);
> +	if (ret)
> +		return ret;
> +
> +	raw = rcdev->raw;
> +
> +	old_array = raw->progs;
> +	ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
> +	if (ret < 0) {
> +		bpf_prog_array_delete_safe(old_array, prog);
> +	} else {
> +		rcu_assign_pointer(raw->progs, new_array);
> +		bpf_prog_array_free(old_array);
> +	}
> +
> +	bpf_prog_put(prog);
> +	mutex_unlock(&rcdev->lock);
> +	return 0;
> +}
> +
> +void rc_dev_bpf_run(struct rc_dev *rcdev, struct ir_raw_event ev)
> +{
> +	struct ir_raw_event_ctrl *raw = rcdev->raw;
> +
> +	if (!raw->progs)
> +		return;
> +
> +	if (unlikely(ev.carrier_report)) {
> +		raw->bpf_rawir_event.carrier = ev.carrier;
> +		raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_CARRIER;
> +	} else {
> +		raw->bpf_rawir_event.duration = ev.duration;
> +
> +		if (ev.pulse)
> +			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_PULSE;
> +		else if (ev.timeout)
> +			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_TIMEOUT;
> +		else if (ev.reset)
> +			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_RESET;
> +		else
> +			raw->bpf_rawir_event.type = BPF_RAWIR_EVENT_SPACE;
> +	}
> +
> +	BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_rawir_event, BPF_PROG_RUN);
> +}
> +
> +void rc_dev_bpf_put(struct rc_dev *rcdev)
> +{
> +	struct bpf_prog_array *progs = rcdev->raw->progs;
> +	int i, size;
> +
> +	if (!progs)
> +		return;
> +
> +	size = bpf_prog_array_length(progs);
> +	for (i = 0; i < size; i++)
> +		bpf_prog_put(progs->progs[i]);
> +
> +	bpf_prog_array_free(rcdev->raw->progs);
> +}
> +
> +int rc_dev_prog_attach(const union bpf_attr *attr)
> +{
> +	struct bpf_prog *prog;
> +	struct rc_dev *rcdev;
> +	int ret;
> +
> +	if (attr->attach_flags)
> +		return -EINVAL;
> +
> +	prog = bpf_prog_get_type(attr->attach_bpf_fd,
> +				 BPF_PROG_TYPE_RAWIR_EVENT);
> +	if (IS_ERR(prog))
> +		return PTR_ERR(prog);
> +
> +	rcdev = rc_dev_get_from_fd(attr->target_fd);
> +	if (IS_ERR(rcdev)) {
> +		bpf_prog_put(prog);
> +		return PTR_ERR(rcdev);
> +	}
> +
> +	ret = rc_dev_bpf_attach(rcdev, prog);
> +	if (ret)
> +		bpf_prog_put(prog);
> +
> +	put_device(&rcdev->dev);
> +
> +	return ret;
> +}
> +
> +int rc_dev_prog_detach(const union bpf_attr *attr)
> +{
> +	struct bpf_prog *prog;
> +	struct rc_dev *rcdev;
> +	int ret;
> +
> +	if (attr->attach_flags)
> +		return -EINVAL;
> +
> +	prog = bpf_prog_get_type(attr->attach_bpf_fd,
> +				 BPF_PROG_TYPE_RAWIR_EVENT);
> +	if (IS_ERR(prog))
> +		return PTR_ERR(prog);
> +
> +	rcdev = rc_dev_get_from_fd(attr->target_fd);
> +	if (IS_ERR(rcdev)) {
> +		bpf_prog_put(prog);
> +		return PTR_ERR(rcdev);
> +	}
> +
> +	ret = rc_dev_bpf_detach(rcdev, prog);
> +
> +	bpf_prog_put(prog);
> +	put_device(&rcdev->dev);
> +
> +	return ret;
> +}
> +
> +int rc_dev_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
> +{
> +	__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
> +	struct bpf_prog_array *progs;
> +	struct rc_dev *rcdev;
> +	u32 cnt, flags = 0;
> +	int ret;
> +
> +	if (attr->query.query_flags)
> +		return -EINVAL;
> +
> +	rcdev = rc_dev_get_from_fd(attr->query.target_fd);
> +	if (IS_ERR(rcdev))
> +		return PTR_ERR(rcdev);
> +
> +	if (rcdev->driver_type != RC_DRIVER_IR_RAW) {
> +		ret = -EINVAL;
> +		goto out;
> +	}
> +
> +	ret = mutex_lock_interruptible(&rcdev->lock);
> +	if (ret)
> +		goto out;
> +
> +	progs = rcdev->raw->progs;
> +	cnt = progs ? bpf_prog_array_length(progs) : 0;
> +
> +	if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {
> +		ret = -EFAULT;
> +		goto out;
> +	}
> +	if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
> +		ret = -EFAULT;
> +		goto out;
> +	}
> +
> +	if (attr->query.prog_cnt != 0 && prog_ids && cnt)
> +		ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
> +
> +out:
> +	mutex_unlock(&rcdev->lock);
> +	put_device(&rcdev->dev);
> +
> +	return ret;
> +}
> diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
> index 24e9fbb80e81..c3028d0366d1 100644
> --- a/drivers/media/rc/lirc_dev.c
> +++ b/drivers/media/rc/lirc_dev.c
> @@ -20,6 +20,7 @@
>  #include <linux/module.h>
>  #include <linux/mutex.h>
>  #include <linux/device.h>
> +#include <linux/file.h>
>  #include <linux/idr.h>
>  #include <linux/poll.h>
>  #include <linux/sched.h>
> @@ -816,4 +817,31 @@ void __exit lirc_dev_exit(void)
>  	unregister_chrdev_region(lirc_base_dev, RC_DEV_MAX);
>  }
>  
> +struct rc_dev *rc_dev_get_from_fd(int fd)
> +{
> +	struct rc_dev *dev;
> +	struct file *f;
> +
> +	f = fget_raw(fd);
> +	if (!f)
> +		return ERR_PTR(-EBADF);
> +
> +	if (!S_ISCHR(f->f_inode->i_mode) ||
> +	    imajor(f->f_inode) != MAJOR(lirc_base_dev)) {
> +		fput(f);
> +		return ERR_PTR(-EBADF);
> +	}
> +
> +	dev = container_of(f->f_inode->i_cdev, struct rc_dev, lirc_cdev);
> +	if (!dev->registered) {
> +		fput(f);
> +		return ERR_PTR(-ENODEV);
> +	}
> +
> +	get_device(&dev->dev);
> +	fput(f);
> +
> +	return dev;
> +}
> +
>  MODULE_ALIAS("lirc_dev");
> diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
> index e0e6a17460f6..6db579f425f1 100644
> --- a/drivers/media/rc/rc-core-priv.h
> +++ b/drivers/media/rc/rc-core-priv.h
> @@ -13,6 +13,7 @@
>  #define	MAX_IR_EVENT_SIZE	512
>  
>  #include <linux/slab.h>
> +#include <uapi/linux/bpf.h>
>  #include <media/rc-core.h>
>  
>  /**
> @@ -57,6 +58,11 @@ struct ir_raw_event_ctrl {
>  	/* raw decoder state follows */
>  	struct ir_raw_event prev_ev;
>  	struct ir_raw_event this_ev;
> +
> +#ifdef CONFIG_BPF_RAWIR_EVENT
> +	struct bpf_rawir_event		bpf_rawir_event;
> +	struct bpf_prog_array		*progs;
> +#endif
>  	struct nec_dec {
>  		int state;
>  		unsigned count;
> @@ -288,6 +294,7 @@ void ir_lirc_raw_event(struct rc_dev *dev, struct ir_raw_event ev);
>  void ir_lirc_scancode_event(struct rc_dev *dev, struct lirc_scancode *lsc);
>  int ir_lirc_register(struct rc_dev *dev);
>  void ir_lirc_unregister(struct rc_dev *dev);
> +struct rc_dev *rc_dev_get_from_fd(int fd);
>  #else
>  static inline int lirc_dev_init(void) { return 0; }
>  static inline void lirc_dev_exit(void) {}
> @@ -299,4 +306,16 @@ static inline int ir_lirc_register(struct rc_dev *dev) { return 0; }
>  static inline void ir_lirc_unregister(struct rc_dev *dev) { }
>  #endif
>  
> +/*
> + * bpf interface
> + */
> +#ifdef CONFIG_BPF_RAWIR_EVENT
> +void rc_dev_bpf_put(struct rc_dev *dev);
> +void rc_dev_bpf_run(struct rc_dev *dev, struct ir_raw_event ev);
> +#else
> +static inline void rc_dev_bpf_put(struct rc_dev *dev) { }
> +static inline void rc_dev_bpf_run(struct rc_dev *dev, struct ir_raw_event ev)
> +{ }
> +#endif
> +
>  #endif /* _RC_CORE_PRIV */
> diff --git a/drivers/media/rc/rc-ir-raw.c b/drivers/media/rc/rc-ir-raw.c
> index 374f83105a23..25828f15faec 100644
> --- a/drivers/media/rc/rc-ir-raw.c
> +++ b/drivers/media/rc/rc-ir-raw.c
> @@ -32,6 +32,7 @@ static int ir_raw_event_thread(void *data)
>  				    handler->protocols || !handler->protocols)
>  					handler->decode(raw->dev, ev);
>  			ir_lirc_raw_event(raw->dev, ev);
> +			rc_dev_bpf_run(raw->dev, ev);
>  			raw->prev_ev = ev;
>  		}
>  		mutex_unlock(&ir_raw_handler_lock);
> @@ -623,6 +624,8 @@ void ir_raw_event_unregister(struct rc_dev *dev)
>  			handler->raw_unregister(dev);
>  	mutex_unlock(&ir_raw_handler_lock);
>  
> +	rc_dev_bpf_put(dev);
> +
>  	ir_raw_event_free(dev);
>  }
>  
> diff --git a/include/linux/bpf_rcdev.h b/include/linux/bpf_rcdev.h
> new file mode 100644
> index 000000000000..17a30f30436a
> --- /dev/null
> +++ b/include/linux/bpf_rcdev.h
> @@ -0,0 +1,30 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _BPF_RCDEV_H
> +#define _BPF_RCDEV_H
> +
> +#include <linux/bpf.h>
> +#include <uapi/linux/bpf.h>
> +
> +#ifdef CONFIG_BPF_RAWIR_EVENT
> +int rc_dev_prog_attach(const union bpf_attr *attr);
> +int rc_dev_prog_detach(const union bpf_attr *attr);
> +int rc_dev_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr);
> +#else
> +static inline int rc_dev_prog_attach(const union bpf_attr *attr)
> +{
> +	return -EINVAL;
> +}
> +
> +static inline int rc_dev_prog_detach(const union bpf_attr *attr)
> +{
> +	return -EINVAL;
> +}
> +
> +static inline int rc_dev_prog_query(const union bpf_attr *attr,
> +				    union bpf_attr __user *uattr)
> +{
> +	return -EINVAL;
> +}
> +#endif
> +
> +#endif /* _BPF_RCDEV_H */
> diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
> index d7df1b323082..667d1d557090 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_BPF_RAWIR_EVENT
> +BPF_PROG_TYPE(BPF_PROG_TYPE_RAWIR_EVENT, rawir_event)
> +#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 02e4112510f8..8ba1be825af0 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -140,6 +140,7 @@ enum bpf_prog_type {
>  	BPF_PROG_TYPE_SK_MSG,
>  	BPF_PROG_TYPE_RAW_TRACEPOINT,
>  	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
> +	BPF_PROG_TYPE_RAWIR_EVENT,
>  };
>  
>  enum bpf_attach_type {
> @@ -157,6 +158,7 @@ enum bpf_attach_type {
>  	BPF_CGROUP_INET6_CONNECT,
>  	BPF_CGROUP_INET4_POST_BIND,
>  	BPF_CGROUP_INET6_POST_BIND,
> +	BPF_RAWIR_EVENT,
>  	__MAX_BPF_ATTACH_TYPE
>  };
>  
> @@ -1855,6 +1857,35 @@ union bpf_attr {
>   *             Egress device index on success, 0 if packet needs to continue
>   *             up the stack for further processing or a negative error in case
>   *             of failure.
> + *
> + * int bpf_rc_keydown(void *ctx, u32 protocol, u32 scancode, u32 toggle)
> + *	Description
> + *		Report decoded scancode with toggle value. For use in
> + *		BPF_PROG_TYPE_RAWIR_EVENT, to report a successfully
> + *		decoded scancode. This is will generate a keydown event,
> + *		and a keyup event once the scancode is no longer repeated.
> + *
> + *		*ctx* pointer to bpf_rawir_event, *protocol* is decoded
> + *		protocol (see RC_PROTO_* enum).
> + *
> + *		Some protocols include a toggle bit, in case the button
> + *		was released and pressed again between consecutive scancodes,
> + *		copy this bit into *toggle* if it exists, else set to 0.
> + *
> + *     Return
> + *		Always return 0 (for now)
> + *
> + * int bpf_rc_repeat(void *ctx)
> + *	Description
> + *		Repeat the last decoded scancode; some IR protocols like
> + *		NEC have a special IR message for repeat last button,
> + *		in case user is holding a button down; the scancode is
> + *		not repeated.
> + *
> + *		*ctx* pointer to bpf_rawir_event.
> + *
> + *     Return
> + *		Always return 0 (for now)
>   */
>  #define __BPF_FUNC_MAPPER(FN)		\
>  	FN(unspec),			\
> @@ -1926,7 +1957,9 @@ union bpf_attr {
>  	FN(skb_get_xfrm_state),		\
>  	FN(get_stack),			\
>  	FN(skb_load_bytes_relative),	\
> -	FN(fib_lookup),
> +	FN(fib_lookup),			\
> +	FN(rc_repeat),			\
> +	FN(rc_keydown),
>  
>  /* integer value in 'imm' field of BPF_CALL instruction selects which helper
>   * function eBPF program intends to call
> @@ -1993,6 +2026,26 @@ enum bpf_hdr_start_off {
>  	BPF_HDR_START_NET,
>  };
>  
> +/*
> + * user accessible mirror of in-kernel ir_raw_event
> + */
> +#define BPF_RAWIR_EVENT_SPACE		0
> +#define BPF_RAWIR_EVENT_PULSE		1
> +#define BPF_RAWIR_EVENT_TIMEOUT		2
> +#define BPF_RAWIR_EVENT_RESET		3
> +#define BPF_RAWIR_EVENT_CARRIER		4
> +#define BPF_RAWIR_EVENT_DUTY_CYCLE	5
> +
> +struct bpf_rawir_event {
> +	union {
> +		__u32	duration;
> +		__u32	carrier;
> +		__u32	duty_cycle;
> +	};
> +
> +	__u32	type;
> +};
> +
>  /* user accessible mirror of in-kernel sk_buff.
>   * new fields can only be added to the end of this structure
>   */
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index e2aeb5e89f44..75c089f407c8 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -11,6 +11,7 @@
>   */
>  #include <linux/bpf.h>
>  #include <linux/bpf_trace.h>
> +#include <linux/bpf_rcdev.h>
>  #include <linux/btf.h>
>  #include <linux/syscalls.h>
>  #include <linux/slab.h>
> @@ -1567,6 +1568,8 @@ static int bpf_prog_attach(const union bpf_attr *attr)
>  	case BPF_SK_SKB_STREAM_PARSER:
>  	case BPF_SK_SKB_STREAM_VERDICT:
>  		return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, true);
> +	case BPF_RAWIR_EVENT:
> +		return rc_dev_prog_attach(attr);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -1637,6 +1640,8 @@ static int bpf_prog_detach(const union bpf_attr *attr)
>  	case BPF_SK_SKB_STREAM_PARSER:
>  	case BPF_SK_SKB_STREAM_VERDICT:
>  		return sockmap_get_from_fd(attr, BPF_PROG_TYPE_SK_SKB, false);
> +	case BPF_RAWIR_EVENT:
> +		return rc_dev_prog_detach(attr);
>  	default:
>  		return -EINVAL;
>  	}
> @@ -1684,6 +1689,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
>  	case BPF_CGROUP_SOCK_OPS:
>  	case BPF_CGROUP_DEVICE:
>  		break;
> +	case BPF_RAWIR_EVENT:
> +		return rc_dev_prog_query(attr, uattr);
>  	default:
>  		return -EINVAL;
>  	}
> -- 
> 2.17.0

[PATCH v2 2/2] bpf: add selftest for rawir_event type program

[Sean Young]

This is simple test over rc-loopback.

Signed-off-by: Sean Young <sean@mess.org>
---
 tools/bpf/bpftool/prog.c                      |  1 +
 tools/include/uapi/linux/bpf.h                | 55 +++++++++++-
 tools/lib/bpf/libbpf.c                        |  1 +
 tools/testing/selftests/bpf/Makefile          |  7 +-
 tools/testing/selftests/bpf/bpf_helpers.h     |  6 ++
 tools/testing/selftests/bpf/test_rawir.sh     | 37 ++++++++
 .../selftests/bpf/test_rawir_event_kern.c     | 26 ++++++
 .../selftests/bpf/test_rawir_event_user.c     | 90 +++++++++++++++++++
 8 files changed, 219 insertions(+), 4 deletions(-)
 create mode 100755 tools/testing/selftests/bpf/test_rawir.sh
 create mode 100644 tools/testing/selftests/bpf/test_rawir_event_kern.c
 create mode 100644 tools/testing/selftests/bpf/test_rawir_event_user.c

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 9bdfdf2d3fbe..8889a4ee8577 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -71,6 +71,7 @@ static const char * const prog_type_name[] = {
 	[BPF_PROG_TYPE_SK_MSG]		= "sk_msg",
 	[BPF_PROG_TYPE_RAW_TRACEPOINT]	= "raw_tracepoint",
 	[BPF_PROG_TYPE_CGROUP_SOCK_ADDR] = "cgroup_sock_addr",
+	[BPF_PROG_TYPE_RAWIR_EVENT]	= "rawir_event",
 };
 
 static void print_boot_time(__u64 nsecs, char *buf, unsigned int size)
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 02e4112510f8..8ba1be825af0 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -140,6 +140,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_SK_MSG,
 	BPF_PROG_TYPE_RAW_TRACEPOINT,
 	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+	BPF_PROG_TYPE_RAWIR_EVENT,
 };
 
 enum bpf_attach_type {
@@ -157,6 +158,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_CONNECT,
 	BPF_CGROUP_INET4_POST_BIND,
 	BPF_CGROUP_INET6_POST_BIND,
+	BPF_RAWIR_EVENT,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -1855,6 +1857,35 @@ union bpf_attr {
  *             Egress device index on success, 0 if packet needs to continue
  *             up the stack for further processing or a negative error in case
  *             of failure.
+ *
+ * int bpf_rc_keydown(void *ctx, u32 protocol, u32 scancode, u32 toggle)
+ *	Description
+ *		Report decoded scancode with toggle value. For use in
+ *		BPF_PROG_TYPE_RAWIR_EVENT, to report a successfully
+ *		decoded scancode. This is will generate a keydown event,
+ *		and a keyup event once the scancode is no longer repeated.
+ *
+ *		*ctx* pointer to bpf_rawir_event, *protocol* is decoded
+ *		protocol (see RC_PROTO_* enum).
+ *
+ *		Some protocols include a toggle bit, in case the button
+ *		was released and pressed again between consecutive scancodes,
+ *		copy this bit into *toggle* if it exists, else set to 0.
+ *
+ *     Return
+ *		Always return 0 (for now)
+ *
+ * int bpf_rc_repeat(void *ctx)
+ *	Description
+ *		Repeat the last decoded scancode; some IR protocols like
+ *		NEC have a special IR message for repeat last button,
+ *		in case user is holding a button down; the scancode is
+ *		not repeated.
+ *
+ *		*ctx* pointer to bpf_rawir_event.
+ *
+ *     Return
+ *		Always return 0 (for now)
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -1926,7 +1957,9 @@ union bpf_attr {
 	FN(skb_get_xfrm_state),		\
 	FN(get_stack),			\
 	FN(skb_load_bytes_relative),	\
-	FN(fib_lookup),
+	FN(fib_lookup),			\
+	FN(rc_repeat),			\
+	FN(rc_keydown),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -1993,6 +2026,26 @@ enum bpf_hdr_start_off {
 	BPF_HDR_START_NET,
 };
 
+/*
+ * user accessible mirror of in-kernel ir_raw_event
+ */
+#define BPF_RAWIR_EVENT_SPACE		0
+#define BPF_RAWIR_EVENT_PULSE		1
+#define BPF_RAWIR_EVENT_TIMEOUT		2
+#define BPF_RAWIR_EVENT_RESET		3
+#define BPF_RAWIR_EVENT_CARRIER		4
+#define BPF_RAWIR_EVENT_DUTY_CYCLE	5
+
+struct bpf_rawir_event {
+	union {
+		__u32	duration;
+		__u32	carrier;
+		__u32	duty_cycle;
+	};
+
+	__u32	type;
+};
+
 /* user accessible mirror of in-kernel sk_buff.
  * new fields can only be added to the end of this structure
  */
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index df54c4c9e48a..372269e9053d 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1455,6 +1455,7 @@ static bool bpf_prog_type__needs_kver(enum bpf_prog_type type)
 	case BPF_PROG_TYPE_CGROUP_DEVICE:
 	case BPF_PROG_TYPE_SK_MSG:
 	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
+	case BPF_PROG_TYPE_RAWIR_EVENT:
 		return false;
 	case BPF_PROG_TYPE_UNSPEC:
 	case BPF_PROG_TYPE_KPROBE:
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 438d4f93875b..d4b7a410c333 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -24,7 +24,7 @@ urandom_read: urandom_read.c
 # Order correspond to 'make run_tests' order
 TEST_GEN_PROGS = test_verifier test_tag test_maps test_lru_map test_lpm_map test_progs \
 	test_align test_verifier_log test_dev_cgroup test_tcpbpf_user \
-	test_sock test_btf test_sockmap
+	test_sock test_btf test_sockmap test_rawir_event_user
 
 TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test_obj_id.o \
 	test_pkt_md_access.o test_xdp_redirect.o test_xdp_meta.o sockmap_parse_prog.o     \
@@ -33,7 +33,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
 	sample_map_ret0.o test_tcpbpf_kern.o test_stacktrace_build_id.o \
 	sockmap_tcp_msg_prog.o connect4_prog.o connect6_prog.o test_adjust_tail.o \
 	test_btf_haskv.o test_btf_nokv.o test_sockmap_kern.o test_tunnel_kern.o \
-	test_get_stack_rawtp.o
+	test_get_stack_rawtp.o test_rawir_event_kern.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
@@ -42,7 +42,8 @@ TEST_PROGS := test_kmod.sh \
 	test_xdp_meta.sh \
 	test_offload.py \
 	test_sock_addr.sh \
-	test_tunnel.sh
+	test_tunnel.sh \
+	test_rawir.sh
 
 # Compile but not part of 'make run_tests'
 TEST_GEN_PROGS_EXTENDED = test_libbpf_open test_sock_addr
diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 2375d06c706b..641af70048bd 100644
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -106,6 +106,12 @@ static int (*bpf_get_stack)(void *ctx, void *buf, int size, int flags) =
 static int (*bpf_fib_lookup)(void *ctx, struct bpf_fib_lookup *params,
 			     int plen, __u32 flags) =
 	(void *) BPF_FUNC_fib_lookup;
+static int (*bpf_rc_repeat)(void *ctx) =
+	(void *) BPF_FUNC_rc_repeat;
+static int (*bpf_rc_keydown)(void *ctx, unsigned protocol, unsigned scancode,
+			     unsigned toggle) =
+	(void *) BPF_FUNC_rc_keydown;
+
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions
diff --git a/tools/testing/selftests/bpf/test_rawir.sh b/tools/testing/selftests/bpf/test_rawir.sh
new file mode 100755
index 000000000000..30529e829af1
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_rawir.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Test bpf_rawir_event over rc-loopback. Steps for the test:
+#
+# 1. Find the /dev/lircN device for rc-loopback
+# 2. Attach bpf_rawir_event program which decodes some IR.
+# 3. Send some IR to the same IR device; since it is loopback, this will
+#    end up in the bpf program
+# 4. bpf program should decode IR and report keycode
+# 5. We can read keycode from same /dev/lirc device
+
+GREEN='\033[0;92m'
+RED='\033[0;31m'
+NC='\033[0m' # No Color
+
+modprobe rc-loopback
+
+for i in /sys/class/rc/rc*
+do
+	if grep -q DRV_NAME=rc-loopback $i/uevent
+	then
+		LIRCDEV=$(grep DEVNAME= $i/lirc*/uevent | sed sQDEVNAME=Q/dev/Q)
+	fi
+done
+
+if [ -n $LIRCDEV ];
+then
+	TYPE=rawir_event
+	./test_rawir_event_user $LIRCDEV
+	ret=$?
+        if [ $ret -ne 0 ]; then
+                echo -e ${RED}"FAIL: $TYPE"${NC}
+                return 1
+        fi
+        echo -e ${GREEN}"PASS: $TYPE"${NC}
+fi
diff --git a/tools/testing/selftests/bpf/test_rawir_event_kern.c b/tools/testing/selftests/bpf/test_rawir_event_kern.c
new file mode 100644
index 000000000000..33ba5d30af62
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_rawir_event_kern.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+// test ir decoder
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+#include <linux/bpf.h>
+#include "bpf_helpers.h"
+
+SEC("rawir_event")
+int bpf_decoder(struct bpf_rawir_event *e)
+{
+	if (e->type == BPF_RAWIR_EVENT_PULSE) {
+		/*
+		 * The lirc interface is microseconds, but here we receive
+		 * nanoseconds.
+		 */
+		int microseconds = e->duration / 1000;
+
+		if (microseconds & 0x10000)
+			bpf_rc_keydown(e, 0x40, microseconds & 0xffff, 0);
+	}
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/tools/testing/selftests/bpf/test_rawir_event_user.c b/tools/testing/selftests/bpf/test_rawir_event_user.c
new file mode 100644
index 000000000000..0d1f711b28f1
--- /dev/null
+++ b/tools/testing/selftests/bpf/test_rawir_event_user.c
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: GPL-2.0
+// test ir decoder
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+#include <linux/bpf.h>
+#include <linux/lirc.h>
+#include <assert.h>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <unistd.h>
+#include <poll.h>
+#include <libgen.h>
+#include <sys/resource.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "bpf_util.h"
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+int main(int argc, char **argv)
+{
+	struct bpf_object *obj;
+	int ret, lircfd, progfd, mode;
+	int testir = 0x1dead;
+
+	if (argc != 2) {
+		printf("Usage: %s /dev/lircN\n", argv[0]);
+		return 2;
+	}
+
+	ret = bpf_prog_load("test_rawir_event_kern.o",
+			    BPF_PROG_TYPE_RAWIR_EVENT, &obj, &progfd);
+	if (ret) {
+		printf("Failed to load bpf program\n");
+		return 1;
+	}
+
+	lircfd = open(argv[1], O_RDWR | O_NONBLOCK);
+	if (lircfd == -1) {
+		printf("failed to open lirc device %s: %m\n", argv[1]);
+		return 1;
+	}
+
+	mode = LIRC_MODE_SCANCODE;
+	if (ioctl(lircfd, LIRC_SET_REC_MODE, &mode)) {
+		printf("failed to set rec mode: %m\n");
+		return 1;
+	}
+
+	ret = bpf_prog_attach(progfd, lircfd, BPF_RAWIR_EVENT, 0);
+	if (ret) {
+		printf("Failed to attach bpf to lirc device: %m\n");
+		return 1;
+	}
+
+	/* Write raw IR */
+	ret = write(lircfd, &testir, sizeof(testir));
+	if (ret != sizeof(testir)) {
+		printf("Failed to send test IR message: %m\n");
+		return 1;
+	}
+
+	struct pollfd pfd = { .fd = lircfd, .events = POLLIN };
+
+	poll(&pfd, 1, 100);
+
+	struct lirc_scancode lsc;
+
+	/* Read decoded IR */
+	ret = read(lircfd, &lsc, sizeof(lsc));
+	if (ret != sizeof(lsc)) {
+		printf("Failed to read decoded IR: %m\n");
+		return 1;
+	}
+
+	if (lsc.scancode != 0xdead || lsc.rc_proto != 64) {
+		printf("Incorrect scancode decoded\n");
+		return 1;
+	}
+
+	return 0;
+}
-- 
2.17.0