1// SPDX-License-Identifier: GPL-2.0
  2
  3//! Crate for all kernel procedural macros.
  4
  5#[macro_use]
  6mod quote;
  7mod concat_idents;
  8mod helpers;
  9mod module;
 10mod paste;
 11mod pin_data;
 12mod pinned_drop;
 13mod vtable;
 14mod zeroable;
 15
 16use proc_macro::TokenStream;
 17
 18/// Declares a kernel module.
 19///
 20/// The `type` argument should be a type which implements the [`Module`]
 21/// trait. Also accepts various forms of kernel metadata.
 22///
 23/// C header: [`include/linux/moduleparam.h`](srctree/include/linux/moduleparam.h)
 24///
 25/// [`Module`]: ../kernel/trait.Module.html
 26///
 27/// # Examples
 28///
 29/// ```ignore
 30/// use kernel::prelude::*;
 31///
 32/// module!{
 33///     type: MyModule,
 34///     name: "my_kernel_module",
 35///     author: "Rust for Linux Contributors",
 36///     description: "My very own kernel module!",
 37///     license: "GPL",
 38///     params: {
 39///        my_i32: i32 {
 40///            default: 42,
 41///            permissions: 0o000,
 42///            description: "Example of i32",
 43///        },
 44///        writeable_i32: i32 {
 45///            default: 42,
 46///            permissions: 0o644,
 47///            description: "Example of i32",
 48///        },
 49///    },
 50/// }
 51///
 52/// struct MyModule;
 53///
 54/// impl kernel::Module for MyModule {
 55///     fn init() -> Result<Self> {
 56///         // If the parameter is writeable, then the kparam lock must be
 57///         // taken to read the parameter:
 58///         {
 59///             let lock = THIS_MODULE.kernel_param_lock();
 60///             pr_info!("i32 param is:  {}\n", writeable_i32.read(&lock));
 61///         }
 62///         // If the parameter is read only, it can be read without locking
 63///         // the kernel parameters:
 64///         pr_info!("i32 param is:  {}\n", my_i32.read());
 65///         Ok(Self)
 66///     }
 67/// }
 68/// ```
 69///
 70/// # Supported argument types
 71///   - `type`: type which implements the [`Module`] trait (required).
 72///   - `name`: byte array of the name of the kernel module (required).
 73///   - `author`: byte array of the author of the kernel module.
 74///   - `description`: byte array of the description of the kernel module.
 75///   - `license`: byte array of the license of the kernel module (required).
 76///   - `alias`: byte array of alias name of the kernel module.
 77#[proc_macro]
 78pub fn module(ts: TokenStream) -> TokenStream {
 79    module::module(ts)
 80}
 81
 82/// Declares or implements a vtable trait.
 83///
 84/// Linux's use of pure vtables is very close to Rust traits, but they differ
 85/// in how unimplemented functions are represented. In Rust, traits can provide
 86/// default implementation for all non-required methods (and the default
 87/// implementation could just return `Error::EINVAL`); Linux typically use C
 88/// `NULL` pointers to represent these functions.
 89///
 90/// This attribute closes that gap. A trait can be annotated with the
 91/// `#[vtable]` attribute. Implementers of the trait will then also have to
 92/// annotate the trait with `#[vtable]`. This attribute generates a `HAS_*`
 93/// associated constant bool for each method in the trait that is set to true if
 94/// the implementer has overridden the associated method.
 95///
 96/// For a trait method to be optional, it must have a default implementation.
 97/// This is also the case for traits annotated with `#[vtable]`, but in this
 98/// case the default implementation will never be executed. The reason for this
 99/// is that the functions will be called through function pointers installed in
100/// C side vtables. When an optional method is not implemented on a `#[vtable]`
101/// trait, a NULL entry is installed in the vtable. Thus the default
102/// implementation is never called. Since these traits are not designed to be
103/// used on the Rust side, it should not be possible to call the default
104/// implementation. This is done to ensure that we call the vtable methods
105/// through the C vtable, and not through the Rust vtable. Therefore, the
106/// default implementation should call `kernel::build_error`, which prevents
107/// calls to this function at compile time:
108///
109/// ```compile_fail
110/// # use kernel::error::VTABLE_DEFAULT_ERROR;
111/// kernel::build_error(VTABLE_DEFAULT_ERROR)
112/// ```
113///
114/// Note that you might need to import [`kernel::error::VTABLE_DEFAULT_ERROR`].
115///
116/// This macro should not be used when all functions are required.
117///
118/// # Examples
119///
120/// ```ignore
121/// use kernel::error::VTABLE_DEFAULT_ERROR;
122/// use kernel::prelude::*;
123///
124/// // Declares a `#[vtable]` trait
125/// #[vtable]
126/// pub trait Operations: Send + Sync + Sized {
127///     fn foo(&self) -> Result<()> {
128///         kernel::build_error(VTABLE_DEFAULT_ERROR)
129///     }
130///
131///     fn bar(&self) -> Result<()> {
132///         kernel::build_error(VTABLE_DEFAULT_ERROR)
133///     }
134/// }
135///
136/// struct Foo;
137///
138/// // Implements the `#[vtable]` trait
139/// #[vtable]
140/// impl Operations for Foo {
141///     fn foo(&self) -> Result<()> {
142/// #        Err(EINVAL)
143///         // ...
144///     }
145/// }
146///
147/// assert_eq!(<Foo as Operations>::HAS_FOO, true);
148/// assert_eq!(<Foo as Operations>::HAS_BAR, false);
149/// ```
150///
151/// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
152#[proc_macro_attribute]
153pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
154    vtable::vtable(attr, ts)
155}
156
157/// Concatenate two identifiers.
158///
159/// This is useful in macros that need to declare or reference items with names
160/// starting with a fixed prefix and ending in a user specified name. The resulting
161/// identifier has the span of the second argument.
162///
163/// # Examples
164///
165/// ```ignore
166/// use kernel::macro::concat_idents;
167///
168/// macro_rules! pub_no_prefix {
169///     ($prefix:ident, $($newname:ident),+) => {
170///         $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+
171///     };
172/// }
173///
174/// pub_no_prefix!(
175///     binder_driver_return_protocol_,
176///     BR_OK,
177///     BR_ERROR,
178///     BR_TRANSACTION,
179///     BR_REPLY,
180///     BR_DEAD_REPLY,
181///     BR_TRANSACTION_COMPLETE,
182///     BR_INCREFS,
183///     BR_ACQUIRE,
184///     BR_RELEASE,
185///     BR_DECREFS,
186///     BR_NOOP,
187///     BR_SPAWN_LOOPER,
188///     BR_DEAD_BINDER,
189///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
190///     BR_FAILED_REPLY
191/// );
192///
193/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
194/// ```
195#[proc_macro]
196pub fn concat_idents(ts: TokenStream) -> TokenStream {
197    concat_idents::concat_idents(ts)
198}
199
200/// Used to specify the pinning information of the fields of a struct.
201///
202/// This is somewhat similar in purpose as
203/// [pin-project-lite](https://crates.io/crates/pin-project-lite).
204/// Place this macro on a struct definition and then `#[pin]` in front of the attributes of each
205/// field you want to structurally pin.
206///
207/// This macro enables the use of the [`pin_init!`] macro. When pin-initializing a `struct`,
208/// then `#[pin]` directs the type of initializer that is required.
209///
210/// If your `struct` implements `Drop`, then you need to add `PinnedDrop` as arguments to this
211/// macro, and change your `Drop` implementation to `PinnedDrop` annotated with
212/// `#[`[`macro@pinned_drop`]`]`, since dropping pinned values requires extra care.
213///
214/// # Examples
215///
216/// ```rust,ignore
217/// #[pin_data]
218/// struct DriverData {
219///     #[pin]
220///     queue: Mutex<Vec<Command>>,
221///     buf: Box<[u8; 1024 * 1024]>,
222/// }
223/// ```
224///
225/// ```rust,ignore
226/// #[pin_data(PinnedDrop)]
227/// struct DriverData {
228///     #[pin]
229///     queue: Mutex<Vec<Command>>,
230///     buf: Box<[u8; 1024 * 1024]>,
231///     raw_info: *mut Info,
232/// }
233///
234/// #[pinned_drop]
235/// impl PinnedDrop for DriverData {
236///     fn drop(self: Pin<&mut Self>) {
237///         unsafe { bindings::destroy_info(self.raw_info) };
238///     }
239/// }
240/// ```
241///
242/// [`pin_init!`]: ../kernel/macro.pin_init.html
243//  ^ cannot use direct link, since `kernel` is not a dependency of `macros`.
244#[proc_macro_attribute]
245pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {
246    pin_data::pin_data(inner, item)
247}
248
249/// Used to implement `PinnedDrop` safely.
250///
251/// Only works on structs that are annotated via `#[`[`macro@pin_data`]`]`.
252///
253/// # Examples
254///
255/// ```rust,ignore
256/// #[pin_data(PinnedDrop)]
257/// struct DriverData {
258///     #[pin]
259///     queue: Mutex<Vec<Command>>,
260///     buf: Box<[u8; 1024 * 1024]>,
261///     raw_info: *mut Info,
262/// }
263///
264/// #[pinned_drop]
265/// impl PinnedDrop for DriverData {
266///     fn drop(self: Pin<&mut Self>) {
267///         unsafe { bindings::destroy_info(self.raw_info) };
268///     }
269/// }
270/// ```
271#[proc_macro_attribute]
272pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
273    pinned_drop::pinned_drop(args, input)
274}
275
276/// Paste identifiers together.
277///
278/// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
279/// single identifier.
280///
281/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
282/// literals (lifetimes and documentation strings are not supported). There is a difference in
283/// supported modifiers as well.
284///
285/// # Example
286///
287/// ```ignore
288/// use kernel::macro::paste;
289///
290/// macro_rules! pub_no_prefix {
291///     ($prefix:ident, $($newname:ident),+) => {
292///         paste! {
293///             $(pub(crate) const $newname: u32 = [<$prefix $newname>];)+
294///         }
295///     };
296/// }
297///
298/// pub_no_prefix!(
299///     binder_driver_return_protocol_,
300///     BR_OK,
301///     BR_ERROR,
302///     BR_TRANSACTION,
303///     BR_REPLY,
304///     BR_DEAD_REPLY,
305///     BR_TRANSACTION_COMPLETE,
306///     BR_INCREFS,
307///     BR_ACQUIRE,
308///     BR_RELEASE,
309///     BR_DECREFS,
310///     BR_NOOP,
311///     BR_SPAWN_LOOPER,
312///     BR_DEAD_BINDER,
313///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
314///     BR_FAILED_REPLY
315/// );
316///
317/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
318/// ```
319///
320/// # Modifiers
321///
322/// For each identifier, it is possible to attach one or multiple modifiers to
323/// it.
324///
325/// Currently supported modifiers are:
326/// * `span`: change the span of concatenated identifier to the span of the specified token. By
327/// default the span of the `[< >]` group is used.
328/// * `lower`: change the identifier to lower case.
329/// * `upper`: change the identifier to upper case.
330///
331/// ```ignore
332/// use kernel::macro::paste;
333///
334/// macro_rules! pub_no_prefix {
335///     ($prefix:ident, $($newname:ident),+) => {
336///         kernel::macros::paste! {
337///             $(pub(crate) const fn [<$newname:lower:span>]: u32 = [<$prefix $newname:span>];)+
338///         }
339///     };
340/// }
341///
342/// pub_no_prefix!(
343///     binder_driver_return_protocol_,
344///     BR_OK,
345///     BR_ERROR,
346///     BR_TRANSACTION,
347///     BR_REPLY,
348///     BR_DEAD_REPLY,
349///     BR_TRANSACTION_COMPLETE,
350///     BR_INCREFS,
351///     BR_ACQUIRE,
352///     BR_RELEASE,
353///     BR_DECREFS,
354///     BR_NOOP,
355///     BR_SPAWN_LOOPER,
356///     BR_DEAD_BINDER,
357///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
358///     BR_FAILED_REPLY
359/// );
360///
361/// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
362/// ```
363///
364/// # Literals
365///
366/// Literals can also be concatenated with other identifiers:
367///
368/// ```ignore
369/// macro_rules! create_numbered_fn {
370///     ($name:literal, $val:literal) => {
371///         kernel::macros::paste! {
372///             fn [<some_ $name _fn $val>]() -> u32 { $val }
373///         }
374///     };
375/// }
376///
377/// create_numbered_fn!("foo", 100);
378///
379/// assert_eq!(some_foo_fn100(), 100)
380/// ```
381///
382/// [`paste`]: https://docs.rs/paste/
383#[proc_macro]
384pub fn paste(input: TokenStream) -> TokenStream {
385    let mut tokens = input.into_iter().collect();
386    paste::expand(&mut tokens);
387    tokens.into_iter().collect()
388}
389
390/// Derives the [`Zeroable`] trait for the given struct.
391///
392/// This can only be used for structs where every field implements the [`Zeroable`] trait.
393///
394/// # Examples
395///
396/// ```rust,ignore
397/// #[derive(Zeroable)]
398/// pub struct DriverData {
399///     id: i64,
400///     buf_ptr: *mut u8,
401///     len: usize,
402/// }
403/// ```
404#[proc_macro_derive(Zeroable)]
405pub fn derive_zeroable(input: TokenStream) -> TokenStream {
406    zeroable::derive(input)
407}