Message-ID: <20180516135511.cvcyb7td2jn3pqfs@gofer.mess.org>
Date:   Wed, 16 May 2018 14:55:11 +0100
From:   Sean Young <sean@...s.org>
To:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        Matthias Reichl <hias@...us.com>,
        Devin Heitmueller <dheitmueller@...nellabs.com>,
        Y Song <ys114321@...il.com>
Subject: Re: [PATCH v2 1/2] media: rc: introduce BPF_PROG_RAWIR_EVENT

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@...s.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@...s.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

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