1 // SPDX-License-Identifier: GPL-2.0
2 
3 //! Crate for all kernel procedural macros.
4 
5 // When fixdep scans this, it will find this string `CONFIG_RUSTC_VERSION_TEXT`
6 // and thus add a dependency on `include/config/RUSTC_VERSION_TEXT`, which is
7 // touched by Kconfig when the version string from the compiler changes.
8 
9 #[macro_use]
10 mod quote;
11 mod concat_idents;
12 mod helpers;
13 mod module;
14 mod paste;
15 mod pin_data;
16 mod pinned_drop;
17 mod vtable;
18 mod zeroable;
19 
20 use proc_macro::TokenStream;
21 
22 /// Declares a kernel module.
23 ///
24 /// The `type` argument should be a type which implements the [`Module`]
25 /// trait. Also accepts various forms of kernel metadata.
26 ///
27 /// C header: [`include/linux/moduleparam.h`](srctree/include/linux/moduleparam.h)
28 ///
29 /// [`Module`]: ../kernel/trait.Module.html
30 ///
31 /// # Examples
32 ///
33 /// ```ignore
34 /// use kernel::prelude::*;
35 ///
36 /// module!{
37 ///     type: MyModule,
38 ///     name: "my_kernel_module",
39 ///     author: "Rust for Linux Contributors",
40 ///     description: "My very own kernel module!",
41 ///     license: "GPL",
42 ///     alias: ["alternate_module_name"],
43 /// }
44 ///
45 /// struct MyModule;
46 ///
47 /// impl kernel::Module for MyModule {
48 ///     fn init() -> Result<Self> {
49 ///         // If the parameter is writeable, then the kparam lock must be
50 ///         // taken to read the parameter:
51 ///         {
52 ///             let lock = THIS_MODULE.kernel_param_lock();
53 ///             pr_info!("i32 param is:  {}\n", writeable_i32.read(&lock));
54 ///         }
55 ///         // If the parameter is read only, it can be read without locking
56 ///         // the kernel parameters:
57 ///         pr_info!("i32 param is:  {}\n", my_i32.read());
58 ///         Ok(Self)
59 ///     }
60 /// }
61 /// ```
62 ///
63 /// ## Firmware
64 ///
65 /// The following example shows how to declare a kernel module that needs
66 /// to load binary firmware files. You need to specify the file names of
67 /// the firmware in the `firmware` field. The information is embedded
68 /// in the `modinfo` section of the kernel module. For example, a tool to
69 /// build an initramfs uses this information to put the firmware files into
70 /// the initramfs image.
71 ///
72 /// ```ignore
73 /// use kernel::prelude::*;
74 ///
75 /// module!{
76 ///     type: MyDeviceDriverModule,
77 ///     name: "my_device_driver_module",
78 ///     author: "Rust for Linux Contributors",
79 ///     description: "My device driver requires firmware",
80 ///     license: "GPL",
81 ///     firmware: ["my_device_firmware1.bin", "my_device_firmware2.bin"],
82 /// }
83 ///
84 /// struct MyDeviceDriverModule;
85 ///
86 /// impl kernel::Module for MyDeviceDriverModule {
87 ///     fn init() -> Result<Self> {
88 ///         Ok(Self)
89 ///     }
90 /// }
91 /// ```
92 ///
93 /// # Supported argument types
94 ///   - `type`: type which implements the [`Module`] trait (required).
95 ///   - `name`: ASCII string literal of the name of the kernel module (required).
96 ///   - `author`: string literal of the author of the kernel module.
97 ///   - `description`: string literal of the description of the kernel module.
98 ///   - `license`: ASCII string literal of the license of the kernel module (required).
99 ///   - `alias`: array of ASCII string literals of the alias names of the kernel module.
100 ///   - `firmware`: array of ASCII string literals of the firmware files of
101 ///     the kernel module.
102 #[proc_macro]
module(ts: TokenStream) -> TokenStream103 pub fn module(ts: TokenStream) -> TokenStream {
104     module::module(ts)
105 }
106 
107 /// Declares or implements a vtable trait.
108 ///
109 /// Linux's use of pure vtables is very close to Rust traits, but they differ
110 /// in how unimplemented functions are represented. In Rust, traits can provide
111 /// default implementation for all non-required methods (and the default
112 /// implementation could just return `Error::EINVAL`); Linux typically use C
113 /// `NULL` pointers to represent these functions.
114 ///
115 /// This attribute closes that gap. A trait can be annotated with the
116 /// `#[vtable]` attribute. Implementers of the trait will then also have to
117 /// annotate the trait with `#[vtable]`. This attribute generates a `HAS_*`
118 /// associated constant bool for each method in the trait that is set to true if
119 /// the implementer has overridden the associated method.
120 ///
121 /// For a trait method to be optional, it must have a default implementation.
122 /// This is also the case for traits annotated with `#[vtable]`, but in this
123 /// case the default implementation will never be executed. The reason for this
124 /// is that the functions will be called through function pointers installed in
125 /// C side vtables. When an optional method is not implemented on a `#[vtable]`
126 /// trait, a NULL entry is installed in the vtable. Thus the default
127 /// implementation is never called. Since these traits are not designed to be
128 /// used on the Rust side, it should not be possible to call the default
129 /// implementation. This is done to ensure that we call the vtable methods
130 /// through the C vtable, and not through the Rust vtable. Therefore, the
131 /// default implementation should call `kernel::build_error`, which prevents
132 /// calls to this function at compile time:
133 ///
134 /// ```compile_fail
135 /// # use kernel::error::VTABLE_DEFAULT_ERROR;
136 /// kernel::build_error(VTABLE_DEFAULT_ERROR)
137 /// ```
138 ///
139 /// Note that you might need to import [`kernel::error::VTABLE_DEFAULT_ERROR`].
140 ///
141 /// This macro should not be used when all functions are required.
142 ///
143 /// # Examples
144 ///
145 /// ```ignore
146 /// use kernel::error::VTABLE_DEFAULT_ERROR;
147 /// use kernel::prelude::*;
148 ///
149 /// // Declares a `#[vtable]` trait
150 /// #[vtable]
151 /// pub trait Operations: Send + Sync + Sized {
152 ///     fn foo(&self) -> Result<()> {
153 ///         kernel::build_error(VTABLE_DEFAULT_ERROR)
154 ///     }
155 ///
156 ///     fn bar(&self) -> Result<()> {
157 ///         kernel::build_error(VTABLE_DEFAULT_ERROR)
158 ///     }
159 /// }
160 ///
161 /// struct Foo;
162 ///
163 /// // Implements the `#[vtable]` trait
164 /// #[vtable]
165 /// impl Operations for Foo {
166 ///     fn foo(&self) -> Result<()> {
167 /// #        Err(EINVAL)
168 ///         // ...
169 ///     }
170 /// }
171 ///
172 /// assert_eq!(<Foo as Operations>::HAS_FOO, true);
173 /// assert_eq!(<Foo as Operations>::HAS_BAR, false);
174 /// ```
175 ///
176 /// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
177 #[proc_macro_attribute]
vtable(attr: TokenStream, ts: TokenStream) -> TokenStream178 pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
179     vtable::vtable(attr, ts)
180 }
181 
182 /// Concatenate two identifiers.
183 ///
184 /// This is useful in macros that need to declare or reference items with names
185 /// starting with a fixed prefix and ending in a user specified name. The resulting
186 /// identifier has the span of the second argument.
187 ///
188 /// # Examples
189 ///
190 /// ```ignore
191 /// use kernel::macro::concat_idents;
192 ///
193 /// macro_rules! pub_no_prefix {
194 ///     ($prefix:ident, $($newname:ident),+) => {
195 ///         $(pub(crate) const $newname: u32 = kernel::macros::concat_idents!($prefix, $newname);)+
196 ///     };
197 /// }
198 ///
199 /// pub_no_prefix!(
200 ///     binder_driver_return_protocol_,
201 ///     BR_OK,
202 ///     BR_ERROR,
203 ///     BR_TRANSACTION,
204 ///     BR_REPLY,
205 ///     BR_DEAD_REPLY,
206 ///     BR_TRANSACTION_COMPLETE,
207 ///     BR_INCREFS,
208 ///     BR_ACQUIRE,
209 ///     BR_RELEASE,
210 ///     BR_DECREFS,
211 ///     BR_NOOP,
212 ///     BR_SPAWN_LOOPER,
213 ///     BR_DEAD_BINDER,
214 ///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
215 ///     BR_FAILED_REPLY
216 /// );
217 ///
218 /// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
219 /// ```
220 #[proc_macro]
concat_idents(ts: TokenStream) -> TokenStream221 pub fn concat_idents(ts: TokenStream) -> TokenStream {
222     concat_idents::concat_idents(ts)
223 }
224 
225 /// Used to specify the pinning information of the fields of a struct.
226 ///
227 /// This is somewhat similar in purpose as
228 /// [pin-project-lite](https://crates.io/crates/pin-project-lite).
229 /// Place this macro on a struct definition and then `#[pin]` in front of the attributes of each
230 /// field you want to structurally pin.
231 ///
232 /// This macro enables the use of the [`pin_init!`] macro. When pin-initializing a `struct`,
233 /// then `#[pin]` directs the type of initializer that is required.
234 ///
235 /// If your `struct` implements `Drop`, then you need to add `PinnedDrop` as arguments to this
236 /// macro, and change your `Drop` implementation to `PinnedDrop` annotated with
237 /// `#[`[`macro@pinned_drop`]`]`, since dropping pinned values requires extra care.
238 ///
239 /// # Examples
240 ///
241 /// ```rust,ignore
242 /// #[pin_data]
243 /// struct DriverData {
244 ///     #[pin]
245 ///     queue: Mutex<Vec<Command>>,
246 ///     buf: Box<[u8; 1024 * 1024]>,
247 /// }
248 /// ```
249 ///
250 /// ```rust,ignore
251 /// #[pin_data(PinnedDrop)]
252 /// struct DriverData {
253 ///     #[pin]
254 ///     queue: Mutex<Vec<Command>>,
255 ///     buf: Box<[u8; 1024 * 1024]>,
256 ///     raw_info: *mut Info,
257 /// }
258 ///
259 /// #[pinned_drop]
260 /// impl PinnedDrop for DriverData {
261 ///     fn drop(self: Pin<&mut Self>) {
262 ///         unsafe { bindings::destroy_info(self.raw_info) };
263 ///     }
264 /// }
265 /// ```
266 ///
267 /// [`pin_init!`]: ../kernel/macro.pin_init.html
268 //  ^ cannot use direct link, since `kernel` is not a dependency of `macros`.
269 #[proc_macro_attribute]
pin_data(inner: TokenStream, item: TokenStream) -> TokenStream270 pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream {
271     pin_data::pin_data(inner, item)
272 }
273 
274 /// Used to implement `PinnedDrop` safely.
275 ///
276 /// Only works on structs that are annotated via `#[`[`macro@pin_data`]`]`.
277 ///
278 /// # Examples
279 ///
280 /// ```rust,ignore
281 /// #[pin_data(PinnedDrop)]
282 /// struct DriverData {
283 ///     #[pin]
284 ///     queue: Mutex<Vec<Command>>,
285 ///     buf: Box<[u8; 1024 * 1024]>,
286 ///     raw_info: *mut Info,
287 /// }
288 ///
289 /// #[pinned_drop]
290 /// impl PinnedDrop for DriverData {
291 ///     fn drop(self: Pin<&mut Self>) {
292 ///         unsafe { bindings::destroy_info(self.raw_info) };
293 ///     }
294 /// }
295 /// ```
296 #[proc_macro_attribute]
pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream297 pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream {
298     pinned_drop::pinned_drop(args, input)
299 }
300 
301 /// Paste identifiers together.
302 ///
303 /// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
304 /// single identifier.
305 ///
306 /// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
307 /// literals (lifetimes and documentation strings are not supported). There is a difference in
308 /// supported modifiers as well.
309 ///
310 /// # Example
311 ///
312 /// ```ignore
313 /// use kernel::macro::paste;
314 ///
315 /// macro_rules! pub_no_prefix {
316 ///     ($prefix:ident, $($newname:ident),+) => {
317 ///         paste! {
318 ///             $(pub(crate) const $newname: u32 = [<$prefix $newname>];)+
319 ///         }
320 ///     };
321 /// }
322 ///
323 /// pub_no_prefix!(
324 ///     binder_driver_return_protocol_,
325 ///     BR_OK,
326 ///     BR_ERROR,
327 ///     BR_TRANSACTION,
328 ///     BR_REPLY,
329 ///     BR_DEAD_REPLY,
330 ///     BR_TRANSACTION_COMPLETE,
331 ///     BR_INCREFS,
332 ///     BR_ACQUIRE,
333 ///     BR_RELEASE,
334 ///     BR_DECREFS,
335 ///     BR_NOOP,
336 ///     BR_SPAWN_LOOPER,
337 ///     BR_DEAD_BINDER,
338 ///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
339 ///     BR_FAILED_REPLY
340 /// );
341 ///
342 /// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
343 /// ```
344 ///
345 /// # Modifiers
346 ///
347 /// For each identifier, it is possible to attach one or multiple modifiers to
348 /// it.
349 ///
350 /// Currently supported modifiers are:
351 /// * `span`: change the span of concatenated identifier to the span of the specified token. By
352 ///   default the span of the `[< >]` group is used.
353 /// * `lower`: change the identifier to lower case.
354 /// * `upper`: change the identifier to upper case.
355 ///
356 /// ```ignore
357 /// use kernel::macro::paste;
358 ///
359 /// macro_rules! pub_no_prefix {
360 ///     ($prefix:ident, $($newname:ident),+) => {
361 ///         kernel::macros::paste! {
362 ///             $(pub(crate) const fn [<$newname:lower:span>]: u32 = [<$prefix $newname:span>];)+
363 ///         }
364 ///     };
365 /// }
366 ///
367 /// pub_no_prefix!(
368 ///     binder_driver_return_protocol_,
369 ///     BR_OK,
370 ///     BR_ERROR,
371 ///     BR_TRANSACTION,
372 ///     BR_REPLY,
373 ///     BR_DEAD_REPLY,
374 ///     BR_TRANSACTION_COMPLETE,
375 ///     BR_INCREFS,
376 ///     BR_ACQUIRE,
377 ///     BR_RELEASE,
378 ///     BR_DECREFS,
379 ///     BR_NOOP,
380 ///     BR_SPAWN_LOOPER,
381 ///     BR_DEAD_BINDER,
382 ///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
383 ///     BR_FAILED_REPLY
384 /// );
385 ///
386 /// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
387 /// ```
388 ///
389 /// # Literals
390 ///
391 /// Literals can also be concatenated with other identifiers:
392 ///
393 /// ```ignore
394 /// macro_rules! create_numbered_fn {
395 ///     ($name:literal, $val:literal) => {
396 ///         kernel::macros::paste! {
397 ///             fn [<some_ $name _fn $val>]() -> u32 { $val }
398 ///         }
399 ///     };
400 /// }
401 ///
402 /// create_numbered_fn!("foo", 100);
403 ///
404 /// assert_eq!(some_foo_fn100(), 100)
405 /// ```
406 ///
407 /// [`paste`]: https://docs.rs/paste/
408 #[proc_macro]
paste(input: TokenStream) -> TokenStream409 pub fn paste(input: TokenStream) -> TokenStream {
410     let mut tokens = input.into_iter().collect();
411     paste::expand(&mut tokens);
412     tokens.into_iter().collect()
413 }
414 
415 /// Derives the [`Zeroable`] trait for the given struct.
416 ///
417 /// This can only be used for structs where every field implements the [`Zeroable`] trait.
418 ///
419 /// # Examples
420 ///
421 /// ```rust,ignore
422 /// #[derive(Zeroable)]
423 /// pub struct DriverData {
424 ///     id: i64,
425 ///     buf_ptr: *mut u8,
426 ///     len: usize,
427 /// }
428 /// ```
429 #[proc_macro_derive(Zeroable)]
derive_zeroable(input: TokenStream) -> TokenStream430 pub fn derive_zeroable(input: TokenStream) -> TokenStream {
431     zeroable::derive(input)
432 }
433