Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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}