Merge branch 'bpf-ir-decoder'

Sean Young says:

====================
The kernel IR decoders (drivers/media/rc/ir-*-decoder.c) 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, for which lircd is need to decode the IR .

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.
It might also be possible to support non-button devices such as analog
directional pads or air conditioning remote controls and decode the target
temperature in bpf, and pass that to an input device.

[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 v4:
 - Renamed rc_dev_bpf_{attach,detach,query} to lirc_bpf_{attach,detach,query}
 - Fixed error path in lirc_bpf_query
 - Rebased on bpf-next

Changes since v3:
 - Implemented review comments from Quentin Monnet and Y Song (thanks!)
 - More helpful and better formatted bpf helper documentation
 - Changed back to bpf_prog_array rather than open-coded implementation
 - scancodes can be 64 bit
 - bpf gets passed values in microseconds, not nanoseconds.
   microseconds is more than than enough (IR receivers support carriers upto
   70kHz, at which point a single period is already 14 microseconds). Also,
   this makes it much more consistent with lirc mode2.
 - Since it looks much more like lirc mode2, rename the program type to
   BPF_PROG_TYPE_LIRC_MODE2.
 - Rebased on bpf-next

Changes since v2:
 - Fixed locking issues
 - Improved self-test to cover more cases
 - Rebased on bpf-next again

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
====================
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>

drivers/media/rc/Kconfig

@@ -25,6 +25,19 @@ config LIRC
 	   passes raw IR to and from userspace, which is needed for
 	   IR transmitting (aka "blasting") and for the lirc daemon.
 
+config BPF_LIRC_MODE2
+	bool "Support for eBPF programs attached to lirc devices"
+	depends on BPF_SYSCALL
+	depends on RC_CORE=y
+	depends on LIRC
+	help
+	   Allow attaching eBPF programs to a lirc device using the bpf(2)
+	   syscall command BPF_PROG_ATTACH. This is supported for raw IR
+	   receivers.
+
+	   These eBPF programs can be used to decode IR into scancodes, for
+	   IR protocols not supported by the kernel decoders.
+
 menuconfig RC_DECODERS
 	bool "Remote controller decoders"
 	depends on RC_CORE

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-$(CONFIG_BPF_LIRC_MODE2) += bpf-lirc.o
 obj-$(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

drivers/media/rc/bpf-lirc.c

+// SPDX-License-Identifier: GPL-2.0
+// bpf-lirc.c - handles bpf
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/bpf_lirc.h>
+#include "rc-core-priv.h"
+
+/*
+ * BPF interface for raw IR
+ */
+const struct bpf_prog_ops lirc_mode2_prog_ops = {
+};
+
+BPF_CALL_1(bpf_rc_repeat, u32*, sample)
+{
+	struct ir_raw_event_ctrl *ctrl;
+
+	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
+
+	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,
+};
+
+/*
+ * Currently rc-core does not support 64-bit scancodes, but there are many
+ * known protocols with more than 32 bits. So, define the interface as u64
+ * as a future-proof.
+ */
+BPF_CALL_4(bpf_rc_keydown, u32*, sample, u32, protocol, u64, scancode,
+	   u32, toggle)
+{
+	struct ir_raw_event_ctrl *ctrl;
+
+	ctrl = container_of(sample, struct ir_raw_event_ctrl, bpf_sample);
+
+	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 *
+lirc_mode2_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;
+	case BPF_FUNC_trace_printk:
+		if (capable(CAP_SYS_ADMIN))
+			return bpf_get_trace_printk_proto();
+		/* fall through */
+	default:
+		return NULL;
+	}
+}
+
+static bool lirc_mode2_is_valid_access(int off, int size,
+				       enum bpf_access_type type,
+				       const struct bpf_prog *prog,
+				       struct bpf_insn_access_aux *info)
+{
+	/* We have one field of u32 */
+	return type == BPF_READ && off == 0 && size == sizeof(u32);
+}
+
+const struct bpf_verifier_ops lirc_mode2_verifier_ops = {
+	.get_func_proto  = lirc_mode2_func_proto,
+	.is_valid_access = lirc_mode2_is_valid_access
+};
+
+#define BPF_MAX_PROGS 64
+
+static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
+{
+	struct bpf_prog_array __rcu *old_array;
+	struct bpf_prog_array *new_array;
+	struct ir_raw_event_ctrl *raw;
+	int ret;
+
+	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
+		return -EINVAL;
+
+	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
+	if (ret)
+		return ret;
+
+	raw = rcdev->raw;
+	if (!raw) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+
+	if (raw->progs && bpf_prog_array_length(raw->progs) >= BPF_MAX_PROGS) {
+		ret = -E2BIG;
+		goto unlock;
+	}
+
+	old_array = raw->progs;
+	ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
+	if (ret < 0)
+		goto unlock;
+
+	rcu_assign_pointer(raw->progs, new_array);
+	bpf_prog_array_free(old_array);
+
+unlock:
+	mutex_unlock(&ir_raw_handler_lock);
+	return ret;
+}
+
+static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
+{
+	struct bpf_prog_array __rcu *old_array;
+	struct bpf_prog_array *new_array;
+	struct ir_raw_event_ctrl *raw;
+	int ret;
+
+	if (rcdev->driver_type != RC_DRIVER_IR_RAW)
+		return -EINVAL;
+
+	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
+	if (ret)
+		return ret;
+
+	raw = rcdev->raw;
+	if (!raw) {
+		ret = -ENODEV;
+		goto unlock;
+	}
+
+	old_array = raw->progs;
+	ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
+	/*
+	 * Do not use bpf_prog_array_delete_safe() as we would end up
+	 * with a dummy entry in the array, and the we would free the
+	 * dummy in lirc_bpf_free()
+	 */
+	if (ret)
+		goto unlock;
+
+	rcu_assign_pointer(raw->progs, new_array);
+	bpf_prog_array_free(old_array);
+unlock:
+	mutex_unlock(&ir_raw_handler_lock);
+	return ret;
+}
+
+void lirc_bpf_run(struct rc_dev *rcdev, u32 sample)
+{
+	struct ir_raw_event_ctrl *raw = rcdev->raw;
+
+	raw->bpf_sample = sample;
+
+	if (raw->progs)
+		BPF_PROG_RUN_ARRAY(raw->progs, &raw->bpf_sample, BPF_PROG_RUN);
+}
+
+/*
+ * This should be called once the rc thread has been stopped, so there can be
+ * no concurrent bpf execution.
+ */
+void lirc_bpf_free(struct rc_dev *rcdev)
+{
+	struct bpf_prog **progs;
+
+	if (!rcdev->raw->progs)
+		return;
+
+	progs = rcu_dereference(rcdev->raw->progs)->progs;
+	while (*progs)
+		bpf_prog_put(*progs++);
+
+	bpf_prog_array_free(rcdev->raw->progs);
+}
+
+int lirc_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_LIRC_MODE2);
+	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 = lirc_bpf_attach(rcdev, prog);
+	if (ret)
+		bpf_prog_put(prog);
+
+	put_device(&rcdev->dev);
+
+	return ret;
+}
+
+int lirc_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_LIRC_MODE2);
+	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 = lirc_bpf_detach(rcdev, prog);
+
+	bpf_prog_put(prog);
+	put_device(&rcdev->dev);
+
+	return ret;
+}
+
+int lirc_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 __rcu *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 put;
+	}
+
+	ret = mutex_lock_interruptible(&ir_raw_handler_lock);
+	if (ret)
+		goto put;
+
+	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 unlock;
+	}
+
+	if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) {
+		ret = -EFAULT;
+		goto unlock;
+	}
+
+	if (attr->query.prog_cnt != 0 && prog_ids && cnt)
+		ret = bpf_prog_array_copy_to_user(progs, prog_ids, cnt);
+
+unlock:
+	mutex_unlock(&ir_raw_handler_lock);
+put:
+	put_device(&rcdev->dev);
+
+	return ret;
+}

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>
@@ -104,6 +105,12 @@ void ir_lirc_raw_event(struct rc_dev *dev, struct ir_raw_event ev)
 			TO_US(ev.duration), TO_STR(ev.pulse));
 	}
 
+	/*
+	 * bpf does not care about the gap generated above; that exists
+	 * for backwards compatibility
+	 */
+	lirc_bpf_run(dev, sample);
+
 	spin_lock_irqsave(&dev->lirc_fh_lock, flags);
 	list_for_each_entry(fh, &dev->lirc_fh, list) {
 		if (LIRC_IS_TIMEOUT(sample) && !fh->send_timeout_reports)
@@ -816,4 +823,27 @@ 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 fd f = fdget(fd);
+	struct lirc_fh *fh;
+	struct rc_dev *dev;
+
+	if (!f.file)
+		return ERR_PTR(-EBADF);
+
+	if (f.file->f_op != &lirc_fops) {
+		fdput(f);
+		return ERR_PTR(-EINVAL);
+	}
+
+	fh = f.file->private_data;
+	dev = fh->rc;
+
+	get_device(&dev->dev);
+	fdput(f);
+
+	return dev;
+}
+
 MODULE_ALIAS("lirc_dev");

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_LIRC_MODE2
+	u32				bpf_sample;
+	struct bpf_prog_array __rcu	*progs;
+#endif
 	struct nec_dec {
 		int state;
 		unsigned count;
@@ -126,6 +132,9 @@ struct ir_raw_event_ctrl {
 	} imon;
 };
 
+/* Mutex for locking raw IR processing and handler change */
+extern struct mutex ir_raw_handler_lock;
+
 /* macros for IR decoders */
 static inline bool geq_margin(unsigned d1, unsigned d2, unsigned margin)
 {
@@ -288,6 +297,7 @@ 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 +309,15 @@ 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_LIRC_MODE2
+void lirc_bpf_free(struct rc_dev *dev);
+void lirc_bpf_run(struct rc_dev *dev, u32 sample);
+#else
+static inline void lirc_bpf_free(struct rc_dev *dev) { }
+static inline void lirc_bpf_run(struct rc_dev *dev, u32 sample) { }
+#endif
+
 #endif /* _RC_CORE_PRIV */

drivers/media/rc/rc-ir-raw.c

@@ -14,7 +14,7 @@
 static LIST_HEAD(ir_raw_client_list);
 
 /* Used to handle IR raw handler extensions */
-static DEFINE_MUTEX(ir_raw_handler_lock);
+DEFINE_MUTEX(ir_raw_handler_lock);
 static LIST_HEAD(ir_raw_handler_list);
 static atomic64_t available_protocols = ATOMIC64_INIT(0);
 
@@ -621,9 +621,17 @@ void ir_raw_event_unregister(struct rc_dev *dev)
 	list_for_each_entry(handler, &ir_raw_handler_list, list)
 		if (handler->raw_unregister)
 			handler->raw_unregister(dev);
-	mutex_unlock(&ir_raw_handler_lock);
+
+	lirc_bpf_free(dev);
 
 	ir_raw_event_free(dev);
+
+	/*
+	 * A user can be calling bpf(BPF_PROG_{QUERY|ATTACH|DETACH}), so
+	 * ensure that the raw member is null on unlock; this is how
+	 * "device gone" is checked.
+	 */
+	mutex_unlock(&ir_raw_handler_lock);
 }
 
 /*

include/linux/bpf_lirc.h

+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BPF_LIRC_H
+#define _BPF_LIRC_H
+
+#include <uapi/linux/bpf.h>
+
+#ifdef CONFIG_BPF_LIRC_MODE2
+int lirc_prog_attach(const union bpf_attr *attr);
+int lirc_prog_detach(const union bpf_attr *attr);
+int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr);
+#else
+static inline int lirc_prog_attach(const union bpf_attr *attr)
+{
+	return -EINVAL;
+}
+
+static inline int lirc_prog_detach(const union bpf_attr *attr)
+{
+	return -EINVAL;
+}
+
+static inline int lirc_prog_query(const union bpf_attr *attr,
+				  union bpf_attr __user *uattr)
+{
+	return -EINVAL;
+}
+#endif
+
+#endif /* _BPF_LIRC_H */

include/linux/bpf_types.h

@@ -26,6 +26,9 @@ 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_LIRC_MODE2
+BPF_PROG_TYPE(BPF_PROG_TYPE_LIRC_MODE2, lirc_mode2)
+#endif
 
 BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)

include/uapi/linux/bpf.h

@@ -143,6 +143,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_RAW_TRACEPOINT,
 	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 	BPF_PROG_TYPE_LWT_SEG6LOCAL,
+	BPF_PROG_TYPE_LIRC_MODE2,
 };
 
 enum bpf_attach_type {
@@ -162,6 +163,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_POST_BIND,
 	BPF_CGROUP_UDP4_SENDMSG,
 	BPF_CGROUP_UDP6_SENDMSG,
+	BPF_LIRC_MODE2,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -2005,6 +2007,53 @@ union bpf_attr {
  * 		direct packet access.
  *	Return
  * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded key press with *scancode*,
+ *		*toggle* value in the given *protocol*. The scancode will be
+ *		translated to a keycode using the rc keymap, and reported as
+ *		an input key down event. After a period a key up event is
+ *		generated. This period can be extended by calling either
+ *		**bpf_rc_keydown** () again with the same values, or calling
+ *		**bpf_rc_repeat** ().
+ *
+ *		Some protocols include a toggle bit, in case the button	was
+ *		released and pressed again between consecutive scancodes.
+ *
+ *		The *ctx* should point to the lirc sample as passed into
+ *		the program.
+ *
+ *		The *protocol* is the decoded protocol number (see
+ *		**enum rc_proto** for some predefined values).
+ *
+ *		This helper is only available is the kernel was compiled with
+ *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ *		"**y**".
+ *
+ *	Return
+ *		0
+ *
+ * int bpf_rc_repeat(void *ctx)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded repeat key message. This delays
+ *		the generation of a key up event for previously generated
+ *		key down event.
+ *
+ *		Some IR protocols like NEC have a special IR message for
+ *		repeating last button, for when a button is held down.
+ *
+ *		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),			\
@@ -2083,7 +2132,9 @@ union bpf_attr {
 	FN(lwt_push_encap),		\
 	FN(lwt_seg6_store_bytes),	\
 	FN(lwt_seg6_adjust_srh),	\
-	FN(lwt_seg6_action),
+	FN(lwt_seg6_action),		\
+	FN(rc_repeat),			\
+	FN(rc_keydown),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call

kernel/bpf/core.c

@@ -1616,6 +1616,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
 	int new_prog_cnt, carry_prog_cnt = 0;
 	struct bpf_prog **existing_prog;
 	struct bpf_prog_array *array;
+	bool found_exclude = false;
 	int new_prog_idx = 0;
 
 	/* Figure out how many existing progs we need to carry over to
@@ -1624,14 +1625,20 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
 	if (old_array) {
 		existing_prog = old_array->progs;
 		for (; *existing_prog; existing_prog++) {
-			if (*existing_prog != exclude_prog &&
-			    *existing_prog != &dummy_bpf_prog.prog)
+			if (*existing_prog == exclude_prog) {
+				found_exclude = true;
+				continue;
+			}
+			if (*existing_prog != &dummy_bpf_prog.prog)
 				carry_prog_cnt++;
 			if (*existing_prog == include_prog)
 				return -EEXIST;
 		}
 	}
 
+	if (exclude_prog && !found_exclude)
+		return -ENOENT;
+
 	/* How many progs (not NULL) will be in the new array? */
 	new_prog_cnt = carry_prog_cnt;
 	if (include_prog)

kernel/bpf/syscall.c

@@ -11,6 +11,7 @@
  */
 #include <linux/bpf.h>
 #include <linux/bpf_trace.h>
+#include <linux/bpf_lirc.h>
 #include <linux/btf.h>
 #include <linux/syscalls.h>
 #include <linux/slab.h>
@@ -1582,6 +1583,8 @@ 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_LIRC_MODE2:
+		return lirc_prog_attach(attr);
 	default:
 		return -EINVAL;
 	}
@@ -1654,6 +1657,8 @@ 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_LIRC_MODE2:
+		return lirc_prog_detach(attr);
 	default:
 		return -EINVAL;
 	}
@@ -1703,6 +1708,8 @@ static int bpf_prog_query(const union bpf_attr *attr,
 	case BPF_CGROUP_SOCK_OPS:
 	case BPF_CGROUP_DEVICE:
 		break;
+	case BPF_LIRC_MODE2:
+		return lirc_prog_query(attr, uattr);
 	default:
 		return -EINVAL;
 	}

kernel/trace/bpf_trace.c

@@ -1006,6 +1006,8 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
 
 	old_array = event->tp_event->prog_array;
 	ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
+	if (ret == -ENOENT)
+		goto unlock;
 	if (ret < 0) {
 		bpf_prog_array_delete_safe(old_array, event->prog);
 	} else {

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_LIRC_MODE2]	= "lirc_mode2",
 };
 
 static void print_boot_time(__u64 nsecs, char *buf, unsigned int size)

tools/include/uapi/linux/bpf.h

@@ -143,6 +143,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_RAW_TRACEPOINT,
 	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 	BPF_PROG_TYPE_LWT_SEG6LOCAL,
+	BPF_PROG_TYPE_LIRC_MODE2,
 };
 
 enum bpf_attach_type {
@@ -162,6 +163,7 @@ enum bpf_attach_type {
 	BPF_CGROUP_INET6_POST_BIND,
 	BPF_CGROUP_UDP4_SENDMSG,
 	BPF_CGROUP_UDP6_SENDMSG,
+	BPF_LIRC_MODE2,
 	__MAX_BPF_ATTACH_TYPE
 };
 
@@ -1852,10 +1854,10 @@ union bpf_attr {
  *		If lookup is successful and result shows packet is to be
  *		forwarded, the neighbor tables are searched for the nexthop.
  *		If successful (ie., FIB lookup shows forwarding and nexthop
- *		is resolved), the nexthop address is returned in ipv4_dst,
- *		ipv6_dst or mpls_out based on family, smac is set to mac
- *		address of egress device, dmac is set to nexthop mac address,
- *		rt_metric is set to metric from route.
+ *		is resolved), the nexthop address is returned in ipv4_dst
+ *		or ipv6_dst based on family, smac is set to mac address of
+ *		egress device, dmac is set to nexthop mac address, rt_metric
+ *		is set to metric from route (IPv4/IPv6 only).
  *
  *             *plen* argument is the size of the passed in struct.
  *             *flags* argument can be a combination of one or more of the
@@ -2005,6 +2007,53 @@ union bpf_attr {
  * 		direct packet access.
  *	Return
  * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded key press with *scancode*,
+ *		*toggle* value in the given *protocol*. The scancode will be
+ *		translated to a keycode using the rc keymap, and reported as
+ *		an input key down event. After a period a key up event is
+ *		generated. This period can be extended by calling either
+ *		**bpf_rc_keydown** () again with the same values, or calling
+ *		**bpf_rc_repeat** ().
+ *
+ *		Some protocols include a toggle bit, in case the button	was
+ *		released and pressed again between consecutive scancodes.
+ *
+ *		The *ctx* should point to the lirc sample as passed into
+ *		the program.
+ *
+ *		The *protocol* is the decoded protocol number (see
+ *		**enum rc_proto** for some predefined values).
+ *
+ *		This helper is only available is the kernel was compiled with
+ *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ *		"**y**".
+ *
+ *	Return
+ *		0
+ *
+ * int bpf_rc_repeat(void *ctx)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded repeat key message. This delays
+ *		the generation of a key up event for previously generated
+ *		key down event.
+ *
+ *		Some IR protocols like NEC have a special IR message for
+ *		repeating last button, for when a button is held down.
+ *
+ *		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),			\
@@ -2083,7 +2132,9 @@ union bpf_attr {
 	FN(lwt_push_encap),		\
 	FN(lwt_seg6_store_bytes),	\
 	FN(lwt_seg6_adjust_srh),	\
-	FN(lwt_seg6_action),
+	FN(lwt_seg6_action),		\
+	FN(rc_repeat),			\
+	FN(rc_keydown),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -2537,8 +2588,10 @@ struct bpf_raw_tracepoint_args {
 #define BPF_FIB_LOOKUP_OUTPUT  BIT(1)
 
 struct bpf_fib_lookup {
-	/* input */
-	__u8	family;   /* network family, AF_INET, AF_INET6, AF_MPLS */
+	/* input:  network family for lookup (AF_INET, AF_INET6)
+	 * output: network family of egress nexthop
+	 */
+	__u8	family;
 
 	/* set if lookup is to consider L4 data - e.g., FIB rules */
 	__u8	l4_protocol;
@@ -2554,22 +2607,20 @@ struct bpf_fib_lookup {
 		__u8	tos;		/* AF_INET  */
 		__be32	flowlabel;	/* AF_INET6 */
 
-		/* output: metric of fib result */
-		__u32 rt_metric;
+		/* output: metric of fib result (IPv4/IPv6 only) */
+		__u32	rt_metric;
 	};
 
 	union {
-		__be32		mpls_in;
 		__be32		ipv4_src;
 		__u32		ipv6_src[4];  /* in6_addr; network order */
 	};
 
-	/* input to bpf_fib_lookup, *dst is destination address.
-	 * output: bpf_fib_lookup sets to gateway address
+	/* input to bpf_fib_lookup, ipv{4,6}_dst is destination address in
+	 * network header. output: bpf_fib_lookup sets to gateway address
+	 * if FIB lookup returns gateway route
 	 */
 	union {
-		/* return for MPLS lookups */
-		__be32		mpls_out[4];  /* support up to 4 labels */
 		__be32		ipv4_dst;
 		__u32		ipv6_dst[4];  /* in6_addr; network order */
 	};

tools/include/uapi/linux/lirc.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * lirc.h - linux infrared remote control header file
+ * last modified 2010/07/13 by Jarod Wilson
+ */
+
+#ifndef _LINUX_LIRC_H
+#define _LINUX_LIRC_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+#define PULSE_BIT       0x01000000
+#define PULSE_MASK      0x00FFFFFF
+
+#define LIRC_MODE2_SPACE     0x00000000
+#define LIRC_MODE2_PULSE     0x01000000
+#define LIRC_MODE2_FREQUENCY 0x02000000
+#define LIRC_MODE2_TIMEOUT   0x03000000
+
+#define LIRC_VALUE_MASK      0x00FFFFFF
+#define LIRC_MODE2_MASK      0xFF000000
+
+#define LIRC_SPACE(val) (((val)&LIRC_VALUE_MASK) | LIRC_MODE2_SPACE)
+#define LIRC_PULSE(val) (((val)&LIRC_VALUE_MASK) | LIRC_MODE2_PULSE)
+#define LIRC_FREQUENCY(val) (((val)&LIRC_VALUE_MASK) | LIRC_MODE2_FREQUENCY)
+#define LIRC_TIMEOUT(val) (((val)&LIRC_VALUE_MASK) | LIRC_MODE2_TIMEOUT)
+
+#define LIRC_VALUE(val) ((val)&LIRC_VALUE_MASK)
+#define LIRC_MODE2(val) ((val)&LIRC_MODE2_MASK)
+
+#define LIRC_IS_SPACE(val) (LIRC_MODE2(val) == LIRC_MODE2_SPACE)
+#define LIRC_IS_PULSE(val) (LIRC_MODE2(val) == LIRC_MODE2_PULSE)
+#define LIRC_IS_FREQUENCY(val) (LIRC_MODE2(val) == LIRC_MODE2_FREQUENCY)
+#define LIRC_IS_TIMEOUT(val) (LIRC_MODE2(val) == LIRC_MODE2_TIMEOUT)
+
+/* used heavily by lirc userspace */
+#define lirc_t int
+
+/*** lirc compatible hardware features ***/
+
+#define LIRC_MODE2SEND(x) (x)
+#define LIRC_SEND2MODE(x) (x)
+#define LIRC_MODE2REC(x) ((x) << 16)
+#define LIRC_REC2MODE(x) ((x) >> 16)
+
+#define LIRC_MODE_RAW                  0x00000001
+#define LIRC_MODE_PULSE                0x00000002
+#define LIRC_MODE_MODE2                0x00000004
+#define LIRC_MODE_SCANCODE             0x00000008
+#define LIRC_MODE_LIRCCODE             0x00000010
+
+
+#define LIRC_CAN_SEND_RAW              LIRC_MODE2SEND(LIRC_MODE_RAW)
+#define LIRC_CAN_SEND_PULSE            LIRC_MODE2SEND(LIRC_MODE_PULSE)
+#define LIRC_CAN_SEND_MODE2            LIRC_MODE2SEND(LIRC_MODE_MODE2)
+#define LIRC_CAN_SEND_LIRCCODE         LIRC_MODE2SEND(LIRC_MODE_LIRCCODE)
+
+#define LIRC_CAN_SEND_MASK             0x0000003f
+
+#define LIRC_CAN_SET_SEND_CARRIER      0x00000100
+#define LIRC_CAN_SET_SEND_DUTY_CYCLE   0x00000200
+#define LIRC_CAN_SET_TRANSMITTER_MASK  0x00000400
+
+#define LIRC_CAN_REC_RAW               LIRC_MODE2REC(LIRC_MODE_RAW)
+#define LIRC_CAN_REC_PULSE             LIRC_MODE2REC(LIRC_MODE_PULSE)
+#define LIRC_CAN_REC_MODE2             LIRC_MODE2REC(LIRC_MODE_MODE2)
+#define LIRC_CAN_REC_SCANCODE          LIRC_MODE2REC(LIRC_MODE_SCANCODE)
+#define LIRC_CAN_REC_LIRCCODE          LIRC_MODE2REC(LIRC_MODE_LIRCCODE)
+
+#define LIRC_CAN_REC_MASK              LIRC_MODE2REC(LIRC_CAN_SEND_MASK)
+
+#define LIRC_CAN_SET_REC_CARRIER       (LIRC_CAN_SET_SEND_CARRIER << 16)
+#define LIRC_CAN_SET_REC_DUTY_CYCLE    (LIRC_CAN_SET_SEND_DUTY_CYCLE << 16)
+
+#define LIRC_CAN_SET_REC_DUTY_CYCLE_RANGE 0x40000000
+#define LIRC_CAN_SET_REC_CARRIER_RANGE    0x80000000
+#define LIRC_CAN_GET_REC_RESOLUTION       0x20000000
+#define LIRC_CAN_SET_REC_TIMEOUT          0x10000000
+#define LIRC_CAN_SET_REC_FILTER           0x08000000
+
+#define LIRC_CAN_MEASURE_CARRIER          0x02000000
+#define LIRC_CAN_USE_WIDEBAND_RECEIVER    0x04000000
+
+#define LIRC_CAN_SEND(x) ((x)&LIRC_CAN_SEND_MASK)
+#define LIRC_CAN_REC(x) ((x)&LIRC_CAN_REC_MASK)
+
+#define LIRC_CAN_NOTIFY_DECODE            0x01000000
+
+/*** IOCTL commands for lirc driver ***/
+
+#define LIRC_GET_FEATURES              _IOR('i', 0x00000000, __u32)
+
+#define LIRC_GET_SEND_MODE             _IOR('i', 0x00000001, __u32)
+#define LIRC_GET_REC_MODE              _IOR('i', 0x00000002, __u32)
+#define LIRC_GET_REC_RESOLUTION        _IOR('i', 0x00000007, __u32)
+
+#define LIRC_GET_MIN_TIMEOUT           _IOR('i', 0x00000008, __u32)
+#define LIRC_GET_MAX_TIMEOUT           _IOR('i', 0x00000009, __u32)
+
+/* code length in bits, currently only for LIRC_MODE_LIRCCODE */
+#define LIRC_GET_LENGTH                _IOR('i', 0x0000000f, __u32)
+
+#define LIRC_SET_SEND_MODE             _IOW('i', 0x00000011, __u32)
+#define LIRC_SET_REC_MODE              _IOW('i', 0x00000012, __u32)
+/* Note: these can reset the according pulse_width */
+#define LIRC_SET_SEND_CARRIER          _IOW('i', 0x00000013, __u32)
+#define LIRC_SET_REC_CARRIER           _IOW('i', 0x00000014, __u32)
+#define LIRC_SET_SEND_DUTY_CYCLE       _IOW('i', 0x00000015, __u32)
+#define LIRC_SET_TRANSMITTER_MASK      _IOW('i', 0x00000017, __u32)
+
+/*
+ * when a timeout != 0 is set the driver will send a
+ * LIRC_MODE2_TIMEOUT data packet, otherwise LIRC_MODE2_TIMEOUT is
+ * never sent, timeout is disabled by default
+ */
+#define LIRC_SET_REC_TIMEOUT           _IOW('i', 0x00000018, __u32)
+
+/* 1 enables, 0 disables timeout reports in MODE2 */
+#define LIRC_SET_REC_TIMEOUT_REPORTS   _IOW('i', 0x00000019, __u32)
+
+/*
+ * if enabled from the next key press on the driver will send
+ * LIRC_MODE2_FREQUENCY packets
+ */
+#define LIRC_SET_MEASURE_CARRIER_MODE	_IOW('i', 0x0000001d, __u32)
+
+/*
+ * to set a range use LIRC_SET_REC_CARRIER_RANGE with the
+ * lower bound first and later LIRC_SET_REC_CARRIER with the upper bound
+ */
+#define LIRC_SET_REC_CARRIER_RANGE     _IOW('i', 0x0000001f, __u32)
+
+#define LIRC_SET_WIDEBAND_RECEIVER     _IOW('i', 0x00000023, __u32)
+
+/*
+ * struct lirc_scancode - decoded scancode with protocol for use with
+ *	LIRC_MODE_SCANCODE
+ *
+ * @timestamp: Timestamp in nanoseconds using CLOCK_MONOTONIC when IR
+ *	was decoded.
+ * @flags: should be 0 for transmit. When receiving scancodes,
+ *	LIRC_SCANCODE_FLAG_TOGGLE or LIRC_SCANCODE_FLAG_REPEAT can be set
+ *	depending on the protocol
+ * @rc_proto: see enum rc_proto
+ * @keycode: the translated keycode. Set to 0 for transmit.
+ * @scancode: the scancode received or to be sent
+ */
+struct lirc_scancode {
+	__u64	timestamp;
+	__u16	flags;
+	__u16	rc_proto;
+	__u32	keycode;
+	__u64	scancode;
+};
+
+/* Set if the toggle bit of rc-5 or rc-6 is enabled */
+#define LIRC_SCANCODE_FLAG_TOGGLE	1
+/* Set if this is a nec or sanyo repeat */
+#define LIRC_SCANCODE_FLAG_REPEAT	2
+
+/**
+ * enum rc_proto - the Remote Controller protocol
+ *
+ * @RC_PROTO_UNKNOWN: Protocol not known
+ * @RC_PROTO_OTHER: Protocol known but proprietary
+ * @RC_PROTO_RC5: Philips RC5 protocol
+ * @RC_PROTO_RC5X_20: Philips RC5x 20 bit protocol
+ * @RC_PROTO_RC5_SZ: StreamZap variant of RC5
+ * @RC_PROTO_JVC: JVC protocol
+ * @RC_PROTO_SONY12: Sony 12 bit protocol
+ * @RC_PROTO_SONY15: Sony 15 bit protocol
+ * @RC_PROTO_SONY20: Sony 20 bit protocol
+ * @RC_PROTO_NEC: NEC protocol
+ * @RC_PROTO_NECX: Extended NEC protocol
+ * @RC_PROTO_NEC32: NEC 32 bit protocol
+ * @RC_PROTO_SANYO: Sanyo protocol
+ * @RC_PROTO_MCIR2_KBD: RC6-ish MCE keyboard
+ * @RC_PROTO_MCIR2_MSE: RC6-ish MCE mouse
+ * @RC_PROTO_RC6_0: Philips RC6-0-16 protocol
+ * @RC_PROTO_RC6_6A_20: Philips RC6-6A-20 protocol
+ * @RC_PROTO_RC6_6A_24: Philips RC6-6A-24 protocol
+ * @RC_PROTO_RC6_6A_32: Philips RC6-6A-32 protocol
+ * @RC_PROTO_RC6_MCE: MCE (Philips RC6-6A-32 subtype) protocol
+ * @RC_PROTO_SHARP: Sharp protocol
+ * @RC_PROTO_XMP: XMP protocol
+ * @RC_PROTO_CEC: CEC protocol
+ * @RC_PROTO_IMON: iMon Pad protocol
+ */
+enum rc_proto {
+	RC_PROTO_UNKNOWN	= 0,
+	RC_PROTO_OTHER		= 1,
+	RC_PROTO_RC5		= 2,
+	RC_PROTO_RC5X_20	= 3,
+	RC_PROTO_RC5_SZ		= 4,
+	RC_PROTO_JVC		= 5,
+	RC_PROTO_SONY12		= 6,
+	RC_PROTO_SONY15		= 7,
+	RC_PROTO_SONY20		= 8,
+	RC_PROTO_NEC		= 9,
+	RC_PROTO_NECX		= 10,
+	RC_PROTO_NEC32		= 11,
+	RC_PROTO_SANYO		= 12,
+	RC_PROTO_MCIR2_KBD	= 13,
+	RC_PROTO_MCIR2_MSE	= 14,
+	RC_PROTO_RC6_0		= 15,
+	RC_PROTO_RC6_6A_20	= 16,
+	RC_PROTO_RC6_6A_24	= 17,
+	RC_PROTO_RC6_6A_32	= 18,
+	RC_PROTO_RC6_MCE	= 19,
+	RC_PROTO_SHARP		= 20,
+	RC_PROTO_XMP		= 21,
+	RC_PROTO_CEC		= 22,
+	RC_PROTO_IMON		= 23,
+};
+
+#endif

tools/lib/bpf/libbpf.c

@@ -1462,6 +1462,7 @@ 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_LIRC_MODE2:
 		return false;
 	case BPF_PROG_TYPE_UNSPEC:
 	case BPF_PROG_TYPE_KPROBE:

tools/testing/selftests/bpf/.gitignore

@@ -17,3 +17,4 @@ test_sock_addr
 urandom_read
 test_btf
 test_sockmap
+test_lirc_mode2_user

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_lirc_mode2_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     \
@@ -34,7 +34,7 @@ TEST_GEN_FILES = test_pkt_access.o test_xdp.o test_l4lb.o test_tcp_estats.o test
 	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_sockmap_kern.o test_sockhash_kern.o \
-	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o
+	test_lwt_seg6local.o sendmsg4_prog.o sendmsg6_prog.o test_lirc_mode2_kern.o
 
 # Order correspond to 'make run_tests' order
 TEST_PROGS := test_kmod.sh \
@@ -44,7 +44,8 @@ TEST_PROGS := test_kmod.sh \
 	test_offload.py \
 	test_sock_addr.sh \
 	test_tunnel.sh \
-	test_lwt_seg6local.sh
+	test_lwt_seg6local.sh \
+	test_lirc_mode2.sh
 
 # Compile but not part of 'make run_tests'
 TEST_GEN_PROGS_EXTENDED = test_libbpf_open test_sock_addr

tools/testing/selftests/bpf/bpf_helpers.h

@@ -126,6 +126,11 @@ static int (*bpf_lwt_seg6_action)(void *ctx, unsigned int action, void *param,
 static int (*bpf_lwt_seg6_adjust_srh)(void *ctx, unsigned int offset,
 				      unsigned int len) =
 	(void *) BPF_FUNC_lwt_seg6_adjust_srh;
+static int (*bpf_rc_repeat)(void *ctx) =
+	(void *) BPF_FUNC_rc_repeat;
+static int (*bpf_rc_keydown)(void *ctx, unsigned int protocol,
+			     unsigned long long scancode, unsigned int 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

tools/testing/selftests/bpf/test_lirc_mode2.sh

+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+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=lirc_mode2
+	./test_lirc_mode2_user $LIRCDEV
+	ret=$?
+	if [ $ret -ne 0 ]; then
+		echo -e ${RED}"FAIL: $TYPE"${NC}
+	else
+		echo -e ${GREEN}"PASS: $TYPE"${NC}
+	fi
+fi

tools/testing/selftests/bpf/test_lirc_mode2_kern.c

+// 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 "bpf_helpers.h"
+
+SEC("lirc_mode2")
+int bpf_decoder(unsigned int *sample)
+{
+	if (LIRC_IS_PULSE(*sample)) {
+		unsigned int duration = LIRC_VALUE(*sample);
+
+		if (duration & 0x10000)
+			bpf_rc_keydown(sample, 0x40, duration & 0xffff, 0);
+	}
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";

tools/testing/selftests/bpf/test_lirc_mode2_user.c

+// SPDX-License-Identifier: GPL-2.0
+// test ir decoder
+//
+// Copyright (C) 2018 Sean Young <sean@mess.org>
+
+// A lirc chardev is a device representing a consumer IR (cir) device which
+// can receive infrared signals from remote control and/or transmit IR.
+//
+// IR is sent as a series of pulses and space somewhat like morse code. The
+// BPF program can decode this into scancodes so that rc-core can translate
+// this into input key codes using the rc keymap.
+//
+// This test works by sending IR over rc-loopback, so the IR is processed by
+// BPF and then decoded into scancodes. The lirc chardev must be the one
+// associated with rc-loopback, see the output of ir-keytable(1).
+//
+// The following CONFIG options must be enabled for the test to succeed:
+// CONFIG_RC_CORE=y
+// CONFIG_BPF_RAWIR_EVENT=y
+// CONFIG_RC_LOOPBACK=y
+
+// Steps:
+// 1. Open the /dev/lircN device for rc-loopback (given on command line)
+// 2. Attach bpf_lirc_mode2 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
+
+#include <linux/bpf.h>
+#include <linux/lirc.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <poll.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;
+	u32 prog_ids[10], prog_flags[10], prog_cnt;
+
+	if (argc != 2) {
+		printf("Usage: %s /dev/lircN\n", argv[0]);
+		return 2;
+	}
+
+	ret = bpf_prog_load("test_lirc_mode2_kern.o",
+			    BPF_PROG_TYPE_LIRC_MODE2, &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;
+	}
+
+	/* Let's try detach it before it was ever attached */
+	ret = bpf_prog_detach2(progfd, lircfd, BPF_LIRC_MODE2);
+	if (ret != -1 || errno != ENOENT) {
+		printf("bpf_prog_detach2 not attached should fail: %m\n");
+		return 1;
+	}
+
+	mode = LIRC_MODE_SCANCODE;
+	if (ioctl(lircfd, LIRC_SET_REC_MODE, &mode)) {
+		printf("failed to set rec mode: %m\n");
+		return 1;
+	}
+
+	prog_cnt = 10;
+	ret = bpf_prog_query(lircfd, BPF_LIRC_MODE2, 0, prog_flags, prog_ids,
+			     &prog_cnt);
+	if (ret) {
+		printf("Failed to query bpf programs on lirc device: %m\n");
+		return 1;
+	}
+
+	if (prog_cnt != 0) {
+		printf("Expected nothing to be attached\n");
+		return 1;
+	}
+
+	ret = bpf_prog_attach(progfd, lircfd, BPF_LIRC_MODE2, 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 };
+	struct lirc_scancode lsc;
+
+	poll(&pfd, 1, 100);
+
+	/* 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;
+	}
+
+	prog_cnt = 10;
+	ret = bpf_prog_query(lircfd, BPF_LIRC_MODE2, 0, prog_flags, prog_ids,
+			     &prog_cnt);
+	if (ret) {
+		printf("Failed to query bpf programs on lirc device: %m\n");
+		return 1;
+	}
+
+	if (prog_cnt != 1) {
+		printf("Expected one program to be attached\n");
+		return 1;
+	}
+
+	/* Let's try detaching it now it is actually attached */
+	ret = bpf_prog_detach2(progfd, lircfd, BPF_LIRC_MODE2);
+	if (ret) {
+		printf("bpf_prog_detach2: returned %m\n");
+		return 1;
+	}
+
+	return 0;
+}