rust/macros/lib.rs - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0

 //! Crate for all kernel procedural macros.

 #[macro_use]
 mod quote;
 mod concat_idents;
 mod helpers;
 mod module;
 mod paste;
 mod pin_data;
 mod pinned_drop;
 mod vtable;
 mod zeroable;

 use proc_macro::TokenStream;

 /// Declares a kernel module.
 ///
 /// The `type` argument should be a type which implements the [`Module`]
 /// trait. Also accepts various forms of kernel metadata.
 ///
 /// C header: [`include/linux/moduleparam.h`](srctree/include/linux/moduleparam.h)
 ///
 /// [`Module`]: ../kernel/trait.Module.html
 ///
 /// # Examples
 ///
 /// ```ignore
 /// use kernel::prelude::*;
 ///
 /// module!{
 ///     type: MyModule,
 ///     name: "my_kernel_module",
 ///     author: "Rust for Linux Contributors",
 ///     description: "My very own kernel module!",
 ///     license: "GPL",
 /// }
 ///
 /// struct MyModule;
 ///
 /// impl kernel::Module for MyModule {
 ///     fn init() -> Result<Self> {
 ///         // If the parameter is writeable, then the kparam lock must be
 ///         // taken to read the parameter:
 ///         {
 ///             let lock = THIS_MODULE.kernel_param_lock();
 ///             pr_info!("i32 param is:  {}\n", writeable_i32.read(&lock));
 ///         }
 ///         // If the parameter is read only, it can be read without locking
 ///         // the kernel parameters:
 ///         pr_info!("i32 param is:  {}\n", my_i32.read());
 ///         Ok(Self)
 ///     }
 /// }
 /// ```
 ///
 /// # Supported argument types
 ///   - `type`: type which implements the [`Module`] trait (required).
 ///   - `name`: byte array of the name of the kernel module (required).
 ///   - `author`: byte array of the author of the kernel module.
 ///   - `description`: byte array of the description of the kernel module.
 ///   - `license`: byte array of the license of the kernel module (required).
 ///   - `alias`: byte array of alias name of the kernel module.
 #[proc_macro]
 pub fn module(ts: TokenStream) -> TokenStream {
     module::module(ts)
 }

 /// Declares or implements a vtable trait.
 ///
 /// Linux's use of pure vtables is very close to Rust traits, but they differ
 /// in how unimplemented functions are represented. In Rust, traits can provide
 /// default implementation for all non-required methods (and the default
 /// implementation could just return `Error::EINVAL`); Linux typically use C
 /// `NULL` pointers to represent these functions.
 ///
 /// This attribute closes that gap. A trait can be annotated with the
 /// `#[vtable]` attribute. Implementers of the trait will then also have to
 /// annotate the trait with `#[vtable]`. This attribute generates a `HAS_*`
 /// associated constant bool for each method in the trait that is set to true if
 /// the implementer has overridden the associated method.
 ///
 /// For a trait method to be optional, it must have a default implementation.
 /// This is also the case for traits annotated with `#[vtable]`, but in this
 /// case the default implementation will never be executed. The reason for this
 /// is that the functions will be called through function pointers installed in
 /// C side vtables. When an optional method is not implemented on a `#[vtable]`
 /// trait, a NULL entry is installed in the vtable. Thus the default
 /// implementation is never called. Since these traits are not designed to be
 /// used on the Rust side, it should not be possible to call the default
 /// implementation. This is done to ensure that we call the vtable methods
 /// through the C vtable, and not through the Rust vtable. Therefore, the
 /// default implementation should call `kernel::build_error`, which prevents
 /// calls to this function at compile time:
 ///
 /// ```compile_fail
 /// # use kernel::error::VTABLE_DEFAULT_ERROR;
 /// kernel::build_error(VTABLE_DEFAULT_ERROR)
 /// ```
 ///
 /// Note that you might need to import [`kernel::error::VTABLE_DEFAULT_ERROR`].
 ///
 /// This macro should not be used when all functions are required.
 ///
 /// # Examples
 ///
 /// ```ignore
 /// use kernel::error::VTABLE_DEFAULT_ERROR;
 /// use kernel::prelude::*;
 ///
 /// // Declares a `#[vtable]` trait
 /// #[vtable]
 /// pub trait Operations: Send + Sync + Sized {
 ///     fn foo(&self) -> Result<()> {
 ///         kernel::build_error(VTABLE_DEFAULT_ERROR)
 ///     }
 ///
 ///     fn bar(&self) -> Result<()> {
 ///         kernel::build_error(VTABLE_DEFAULT_ERROR)
 ///     }
 /// }
 ///
 /// struct Foo;
 ///
 /// // Implements the `#[vtable]` trait
 /// #[vtable]
 /// impl Operations for Foo {
 ///     fn foo(&self) -> Result<()> {
 /// #        Err(EINVAL)
 ///         // ...
 ///     }
 /// }
 ///
 /// assert_eq!(<Foo as Operations>::HAS_FOO, true);
 /// assert_eq!(<Foo as Operations>::HAS_BAR, false);
 /// ```
 ///
 /// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
 #[proc_macro_attribute]
 pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
     vtable::vtable(attr, ts)
 }

 /// Concatenate two identifiers.
 ///
 /// This is useful in macros that need to declare or reference items with names
 /// starting with a fixed prefix and ending in a user specified name. The resulting
 /// identifier has the span of the second argument.
 ///
 /// # Examples
 ///
 /// ```ignore
 /// use kernel::macro::concat_idents;
 ///
 /// macro_rules! pub_no_prefix {
 ///     ($prefix:ident, $($newname:ident),+) => {
 ///         $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+
 ///     };
 /// }
 ///
 /// pub_no_prefix!(
 ///     binder_driver_return_protocol_,
 ///     BR_OK,
 ///     BR_ERROR,
 ///     BR_TRANSACTION,
 ///     BR_REPLY,
 ///     BR_DEAD_REPLY,
 ///     BR_TRANSACTION_COMPLETE,
 ///     BR_INCREFS,
 ///     BR_ACQUIRE,
 ///     BR_RELEASE,
 ///     BR_DECREFS,
 ///     BR_NOOP,
 ///     BR_SPAWN_LOOPER,
 ///     BR_DEAD_BINDER,
 ///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
 ///     BR_FAILED_REPLY
 /// );
 ///
 /// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
 /// ```
 #[proc_macro]
 pub fn concat_idents(ts: TokenStream) -> TokenStream {
     concat_idents::concat_idents(ts)
 }

 /// Used to specify the pinning information of the fields of a struct.
 ///
 /// This is somewhat similar in purpose as
 /// [pin-project-lite](https://crates.io/crates/pin-project-lite).
 /// Place this macro on a struct definition and then `#[pin]` in front of the attributes of each
 /// field you want to structurally pin.
 ///
 /// This macro enables the use of the [`pin_init!`] macro. When pin-initializing a `struct`,
 /// then `#[pin]` directs the type of initializer that is required.
 ///
 /// If your `struct` implements `Drop`, then you need to add `PinnedDrop` as arguments to this
 /// macro, and change your `Drop` implementation to `PinnedDrop` annotated with
 /// `#[`[`macro@pinned_drop`]`]`, since dropping pinned values requires extra care.
 ///
 /// # Examples
 ///
 /// ```rust,ignore
 /// #[pin_data]
 /// struct DriverData {
 ///     #[pin]
 ///     queue: Mutex<Vec<Command>>,
 ///     buf: Box<[u8; 1024 * 1024]>,
 /// }
 /// ```
 ///
 /// ```rust,ignore
 /// #[pin_data(PinnedDrop)]
 /// struct DriverData {
 ///     #[pin]
 ///     queue: Mutex<Vec<Command>>,
 ///     buf: Box<[u8; 1024 * 1024]>,
 ///     raw_info: *mut Info,
 /// }
 ///
 /// #[pinned_drop]
 /// impl PinnedDrop for DriverData {
 ///     fn drop(self: Pin<&mut Self>) {
 ///         unsafe { bindings::destroy_info(self.raw_info) };
 ///     }
 /// }
 /// ```
 ///
 /// [`pin_init!`]: ../kernel/macro.pin_init.html
 //  ^ cannot use direct link, since `kernel` is not a dependency of `macros`.
 #[proc_macro_attribute]
 pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {
     pin_data::pin_data(inner, item)
 }

 /// Used to implement `PinnedDrop` safely.
 ///
 /// Only works on structs that are annotated via `#[`[`macro@pin_data`]`]`.
 ///
 /// # Examples
 ///
 /// ```rust,ignore
 /// #[pin_data(PinnedDrop)]
 /// struct DriverData {
 ///     #[pin]
 ///     queue: Mutex<Vec<Command>>,
 ///     buf: Box<[u8; 1024 * 1024]>,
 ///     raw_info: *mut Info,
 /// }
 ///
 /// #[pinned_drop]
 /// impl PinnedDrop for DriverData {
 ///     fn drop(self: Pin<&mut Self>) {
 ///         unsafe { bindings::destroy_info(self.raw_info) };
 ///     }
 /// }
 /// ```
 #[proc_macro_attribute]
 pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
     pinned_drop::pinned_drop(args, input)
 }

 /// Paste identifiers together.
 ///
 /// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
 /// single identifier.
 ///
 /// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
 /// literals (lifetimes and documentation strings are not supported). There is a difference in
 /// supported modifiers as well.
 ///
 /// # Example
 ///
 /// ```ignore
 /// use kernel::macro::paste;
 ///
 /// macro_rules! pub_no_prefix {
 ///     ($prefix:ident, $($newname:ident),+) => {
 ///         paste! {
 ///             $(pub(crate) const $newname: u32 = [<$prefix $newname>];)+
 ///         }
 ///     };
 /// }
 ///
 /// pub_no_prefix!(
 ///     binder_driver_return_protocol_,
 ///     BR_OK,
 ///     BR_ERROR,
 ///     BR_TRANSACTION,
 ///     BR_REPLY,
 ///     BR_DEAD_REPLY,
 ///     BR_TRANSACTION_COMPLETE,
 ///     BR_INCREFS,
 ///     BR_ACQUIRE,
 ///     BR_RELEASE,
 ///     BR_DECREFS,
 ///     BR_NOOP,
 ///     BR_SPAWN_LOOPER,
 ///     BR_DEAD_BINDER,
 ///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
 ///     BR_FAILED_REPLY
 /// );
 ///
 /// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
 /// ```
 ///
 /// # Modifiers
 ///
 /// For each identifier, it is possible to attach one or multiple modifiers to
 /// it.
 ///
 /// Currently supported modifiers are:
 /// * `span`: change the span of concatenated identifier to the span of the specified token. By
 /// default the span of the `[< >]` group is used.
 /// * `lower`: change the identifier to lower case.
 /// * `upper`: change the identifier to upper case.
 ///
 /// ```ignore
 /// use kernel::macro::paste;
 ///
 /// macro_rules! pub_no_prefix {
 ///     ($prefix:ident, $($newname:ident),+) => {
 ///         kernel::macros::paste! {
 ///             $(pub(crate) const fn [<$newname:lower:span>]: u32 = [<$prefix $newname:span>];)+
 ///         }
 ///     };
 /// }
 ///
 /// pub_no_prefix!(
 ///     binder_driver_return_protocol_,
 ///     BR_OK,
 ///     BR_ERROR,
 ///     BR_TRANSACTION,
 ///     BR_REPLY,
 ///     BR_DEAD_REPLY,
 ///     BR_TRANSACTION_COMPLETE,
 ///     BR_INCREFS,
 ///     BR_ACQUIRE,
 ///     BR_RELEASE,
 ///     BR_DECREFS,
 ///     BR_NOOP,
 ///     BR_SPAWN_LOOPER,
 ///     BR_DEAD_BINDER,
 ///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
 ///     BR_FAILED_REPLY
 /// );
 ///
 /// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
 /// ```
 ///
 /// # Literals
 ///
 /// Literals can also be concatenated with other identifiers:
 ///
 /// ```ignore
 /// macro_rules! create_numbered_fn {
 ///     ($name:literal, $val:literal) => {
 ///         kernel::macros::paste! {
 ///             fn [<some_ $name _fn $val>]() -> u32 { $val }
 ///         }
 ///     };
 /// }
 ///
 /// create_numbered_fn!("foo", 100);
 ///
 /// assert_eq!(some_foo_fn100(), 100)
 /// ```
 ///
 /// [`paste`]: https://docs.rs/paste/
 #[proc_macro]
 pub fn paste(input: TokenStream) -> TokenStream {
     let mut tokens = input.into_iter().collect();
     paste::expand(&mut tokens);
     tokens.into_iter().collect()
 }

 /// Derives the [`Zeroable`] trait for the given struct.
 ///
 /// This can only be used for structs where every field implements the [`Zeroable`] trait.
 ///
 /// # Examples
 ///
 /// ```rust,ignore
 /// #[derive(Zeroable)]
 /// pub struct DriverData {
 ///     id: i64,
 ///     buf_ptr: *mut u8,
 ///     len: usize,
 /// }
 /// ```
 #[proc_macro_derive(Zeroable)]
 pub fn derive_zeroable(input: TokenStream) -> TokenStream {
     zeroable::derive(input)
 }
	// SPDX-License-Identifier: GPL-2.0

	//! Crate for all kernel procedural macros.

	#[macro_use]
	mod quote;
	mod concat_idents;
	mod helpers;
	mod module;
	mod paste;
	mod pin_data;
	mod pinned_drop;
	mod vtable;
	mod zeroable;

	use proc_macro::TokenStream;

	/// Declares a kernel module.
	///
	/// The `type` argument should be a type which implements the [`Module`]
	/// trait. Also accepts various forms of kernel metadata.
	///
	/// C header: [`include/linux/moduleparam.h`](srctree/include/linux/moduleparam.h)
	///
	/// [`Module`]: ../kernel/trait.Module.html
	///
	/// # Examples
	///
	/// ```ignore
	/// use kernel::prelude::*;
	///
	/// module!{
	/// type: MyModule,
	/// name: "my_kernel_module",
	/// author: "Rust for Linux Contributors",
	/// description: "My very own kernel module!",
	/// license: "GPL",
	/// }
	///
	/// struct MyModule;
	///
	/// impl kernel::Module for MyModule {
	/// fn init() -> Result<Self> {
	/// // If the parameter is writeable, then the kparam lock must be
	/// // taken to read the parameter:
	/// {
	/// let lock = THIS_MODULE.kernel_param_lock();
	/// pr_info!("i32 param is: {}\n", writeable_i32.read(&lock));
	/// }
	/// // If the parameter is read only, it can be read without locking
	/// // the kernel parameters:
	/// pr_info!("i32 param is: {}\n", my_i32.read());
	/// Ok(Self)
	/// }
	/// }
	/// ```
	///
	/// # Supported argument types
	/// - `type`: type which implements the [`Module`] trait (required).
	/// - `name`: byte array of the name of the kernel module (required).
	/// - `author`: byte array of the author of the kernel module.
	/// - `description`: byte array of the description of the kernel module.
	/// - `license`: byte array of the license of the kernel module (required).
	/// - `alias`: byte array of alias name of the kernel module.
	#[proc_macro]
	pub fn module(ts: TokenStream) -> TokenStream {
	module::module(ts)
	}

	/// Declares or implements a vtable trait.
	///
	/// Linux's use of pure vtables is very close to Rust traits, but they differ
	/// in how unimplemented functions are represented. In Rust, traits can provide
	/// default implementation for all non-required methods (and the default
	/// implementation could just return `Error::EINVAL`); Linux typically use C
	/// `NULL` pointers to represent these functions.
	///
	/// This attribute closes that gap. A trait can be annotated with the
	/// `#[vtable]` attribute. Implementers of the trait will then also have to
	/// annotate the trait with `#[vtable]`. This attribute generates a `HAS_*`
	/// associated constant bool for each method in the trait that is set to true if
	/// the implementer has overridden the associated method.
	///
	/// For a trait method to be optional, it must have a default implementation.
	/// This is also the case for traits annotated with `#[vtable]`, but in this
	/// case the default implementation will never be executed. The reason for this
	/// is that the functions will be called through function pointers installed in
	/// C side vtables. When an optional method is not implemented on a `#[vtable]`
	/// trait, a NULL entry is installed in the vtable. Thus the default
	/// implementation is never called. Since these traits are not designed to be
	/// used on the Rust side, it should not be possible to call the default
	/// implementation. This is done to ensure that we call the vtable methods
	/// through the C vtable, and not through the Rust vtable. Therefore, the
	/// default implementation should call `kernel::build_error`, which prevents
	/// calls to this function at compile time:
	///
	/// ```compile_fail
	/// # use kernel::error::VTABLE_DEFAULT_ERROR;
	/// kernel::build_error(VTABLE_DEFAULT_ERROR)
	/// ```
	///
	/// Note that you might need to import [`kernel::error::VTABLE_DEFAULT_ERROR`].
	///
	/// This macro should not be used when all functions are required.
	///
	/// # Examples
	///
	/// ```ignore
	/// use kernel::error::VTABLE_DEFAULT_ERROR;
	/// use kernel::prelude::*;
	///
	/// // Declares a `#[vtable]` trait
	/// #[vtable]
	/// pub trait Operations: Send + Sync + Sized {
	/// fn foo(&self) -> Result<()> {
	/// kernel::build_error(VTABLE_DEFAULT_ERROR)
	/// }
	///
	/// fn bar(&self) -> Result<()> {
	/// kernel::build_error(VTABLE_DEFAULT_ERROR)
	/// }
	/// }
	///
	/// struct Foo;
	///
	/// // Implements the `#[vtable]` trait
	/// #[vtable]
	/// impl Operations for Foo {
	/// fn foo(&self) -> Result<()> {
	/// # Err(EINVAL)
	/// // ...
	/// }
	/// }
	///
	/// assert_eq!(<Foo as Operations>::HAS_FOO, true);
	/// assert_eq!(<Foo as Operations>::HAS_BAR, false);
	/// ```
	///
	/// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
	#[proc_macro_attribute]
	pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
	vtable::vtable(attr, ts)
	}

	/// Concatenate two identifiers.
	///
	/// This is useful in macros that need to declare or reference items with names
	/// starting with a fixed prefix and ending in a user specified name. The resulting
	/// identifier has the span of the second argument.
	///
	/// # Examples
	///
	/// ```ignore
	/// use kernel::macro::concat_idents;
	///
	/// macro_rules! pub_no_prefix {
	/// ($prefix:ident, $($newname:ident),+) => {
	/// $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+
	/// };
	/// }
	///
	/// pub_no_prefix!(
	/// binder_driver_return_protocol_,
	/// BR_OK,
	/// BR_ERROR,
	/// BR_TRANSACTION,
	/// BR_REPLY,
	/// BR_DEAD_REPLY,
	/// BR_TRANSACTION_COMPLETE,
	/// BR_INCREFS,
	/// BR_ACQUIRE,
	/// BR_RELEASE,
	/// BR_DECREFS,
	/// BR_NOOP,
	/// BR_SPAWN_LOOPER,
	/// BR_DEAD_BINDER,
	/// BR_CLEAR_DEATH_NOTIFICATION_DONE,
	/// BR_FAILED_REPLY
	/// );
	///
	/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
	/// ```
	#[proc_macro]
	pub fn concat_idents(ts: TokenStream) -> TokenStream {
	concat_idents::concat_idents(ts)
	}

	/// Used to specify the pinning information of the fields of a struct.
	///
	/// This is somewhat similar in purpose as
	/// [pin-project-lite](https://crates.io/crates/pin-project-lite).
	/// Place this macro on a struct definition and then `#[pin]` in front of the attributes of each
	/// field you want to structurally pin.
	///
	/// This macro enables the use of the [`pin_init!`] macro. When pin-initializing a `struct`,
	/// then `#[pin]` directs the type of initializer that is required.
	///
	/// If your `struct` implements `Drop`, then you need to add `PinnedDrop` as arguments to this
	/// macro, and change your `Drop` implementation to `PinnedDrop` annotated with
	/// `#[`[`macro@pinned_drop`]`]`, since dropping pinned values requires extra care.
	///
	/// # Examples
	///
	/// ```rust,ignore
	/// #[pin_data]
	/// struct DriverData {
	/// #[pin]
	/// queue: Mutex<Vec<Command>>,
	/// buf: Box<[u8; 1024 * 1024]>,
	/// }
	/// ```
	///
	/// ```rust,ignore
	/// #[pin_data(PinnedDrop)]
	/// struct DriverData {
	/// #[pin]
	/// queue: Mutex<Vec<Command>>,
	/// buf: Box<[u8; 1024 * 1024]>,
	/// raw_info: *mut Info,
	/// }
	///
	/// #[pinned_drop]
	/// impl PinnedDrop for DriverData {
	/// fn drop(self: Pin<&mut Self>) {
	/// unsafe { bindings::destroy_info(self.raw_info) };
	/// }
	/// }
	/// ```
	///
	/// [`pin_init!`]: ../kernel/macro.pin_init.html
	// ^ cannot use direct link, since `kernel` is not a dependency of `macros`.
	#[proc_macro_attribute]
	pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {
	pin_data::pin_data(inner, item)
	}

	/// Used to implement `PinnedDrop` safely.
	///
	/// Only works on structs that are annotated via `#[`[`macro@pin_data`]`]`.
	///
	/// # Examples
	///
	/// ```rust,ignore
	/// #[pin_data(PinnedDrop)]
	/// struct DriverData {
	/// #[pin]
	/// queue: Mutex<Vec<Command>>,
	/// buf: Box<[u8; 1024 * 1024]>,
	/// raw_info: *mut Info,
	/// }
	///
	/// #[pinned_drop]
	/// impl PinnedDrop for DriverData {
	/// fn drop(self: Pin<&mut Self>) {
	/// unsafe { bindings::destroy_info(self.raw_info) };
	/// }
	/// }
	/// ```
	#[proc_macro_attribute]
	pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
	pinned_drop::pinned_drop(args, input)
	}

	/// Paste identifiers together.
	///
	/// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
	/// single identifier.
	///
	/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
	/// literals (lifetimes and documentation strings are not supported). There is a difference in
	/// supported modifiers as well.
	///
	/// # Example
	///
	/// ```ignore
	/// use kernel::macro::paste;
	///
	/// macro_rules! pub_no_prefix {
	/// ($prefix:ident, $($newname:ident),+) => {
	/// paste! {
	/// $(pub(crate) const $newname: u32 = [<$prefix $newname>];)+
	/// }
	/// };
	/// }
	///
	/// pub_no_prefix!(
	/// binder_driver_return_protocol_,
	/// BR_OK,
	/// BR_ERROR,
	/// BR_TRANSACTION,
	/// BR_REPLY,
	/// BR_DEAD_REPLY,
	/// BR_TRANSACTION_COMPLETE,
	/// BR_INCREFS,
	/// BR_ACQUIRE,
	/// BR_RELEASE,
	/// BR_DECREFS,
	/// BR_NOOP,
	/// BR_SPAWN_LOOPER,
	/// BR_DEAD_BINDER,
	/// BR_CLEAR_DEATH_NOTIFICATION_DONE,
	/// BR_FAILED_REPLY
	/// );
	///
	/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
	/// ```
	///
	/// # Modifiers
	///
	/// For each identifier, it is possible to attach one or multiple modifiers to
	/// it.
	///
	/// Currently supported modifiers are:
	/// * `span`: change the span of concatenated identifier to the span of the specified token. By
	/// default the span of the `[< >]` group is used.
	/// * `lower`: change the identifier to lower case.
	/// * `upper`: change the identifier to upper case.
	///
	/// ```ignore
	/// use kernel::macro::paste;
	///
	/// macro_rules! pub_no_prefix {
	/// ($prefix:ident, $($newname:ident),+) => {
	/// kernel::macros::paste! {
	/// $(pub(crate) const fn [<$newname:lower:span>]: u32 = [<$prefix $newname:span>];)+
	/// }
	/// };
	/// }
	///
	/// pub_no_prefix!(
	/// binder_driver_return_protocol_,
	/// BR_OK,
	/// BR_ERROR,
	/// BR_TRANSACTION,
	/// BR_REPLY,
	/// BR_DEAD_REPLY,
	/// BR_TRANSACTION_COMPLETE,
	/// BR_INCREFS,
	/// BR_ACQUIRE,
	/// BR_RELEASE,
	/// BR_DECREFS,
	/// BR_NOOP,
	/// BR_SPAWN_LOOPER,
	/// BR_DEAD_BINDER,
	/// BR_CLEAR_DEATH_NOTIFICATION_DONE,
	/// BR_FAILED_REPLY
	/// );
	///
	/// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
	/// ```
	///
	/// # Literals
	///
	/// Literals can also be concatenated with other identifiers:
	///
	/// ```ignore
	/// macro_rules! create_numbered_fn {
	/// ($name:literal, $val:literal) => {
	/// kernel::macros::paste! {
	/// fn [<some_ $name _fn $val>]() -> u32 { $val }
	/// }
	/// };
	/// }
	///
	/// create_numbered_fn!("foo", 100);
	///
	/// assert_eq!(some_foo_fn100(), 100)
	/// ```
	///
	/// [`paste`]: https://docs.rs/paste/
	#[proc_macro]
	pub fn paste(input: TokenStream) -> TokenStream {
	let mut tokens = input.into_iter().collect();
	paste::expand(&mut tokens);
	tokens.into_iter().collect()
	}

	/// Derives the [`Zeroable`] trait for the given struct.
	///
	/// This can only be used for structs where every field implements the [`Zeroable`] trait.
	///
	/// # Examples
	///
	/// ```rust,ignore
	/// #[derive(Zeroable)]
	/// pub struct DriverData {
	/// id: i64,
	/// buf_ptr: *mut u8,
	/// len: usize,
	/// }
	/// ```
	#[proc_macro_derive(Zeroable)]
	pub fn derive_zeroable(input: TokenStream) -> TokenStream {
	zeroable::derive(input)
	}