macros/
lib.rs

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// Stable since Rust 1.88.0 under a different name, `proc_macro_span_file`,
10// which was added in Rust 1.88.0. This is why `cfg_attr` is used here, i.e.
11// to avoid depending on the full `proc_macro_span` on Rust >= 1.88.0.
12#![cfg_attr(not(CONFIG_RUSTC_HAS_SPAN_FILE), feature(proc_macro_span))]
13
14#[macro_use]
15mod quote;
16mod concat_idents;
17mod export;
18mod fmt;
19mod helpers;
20mod kunit;
21mod module;
22mod paste;
23mod vtable;
24
25use proc_macro::TokenStream;
26
27/// Declares a kernel module.
28///
29/// The `type` argument should be a type which implements the [`Module`]
30/// trait. Also accepts various forms of kernel metadata.
31///
32/// The `params` field describe module parameters. Each entry has the form
33///
34/// ```ignore
35/// parameter_name: type {
36///     default: default_value,
37///     description: "Description",
38/// }
39/// ```
40///
41/// `type` may be one of
42///
43/// - [`i8`]
44/// - [`u8`]
45/// - [`i8`]
46/// - [`u8`]
47/// - [`i16`]
48/// - [`u16`]
49/// - [`i32`]
50/// - [`u32`]
51/// - [`i64`]
52/// - [`u64`]
53/// - [`isize`]
54/// - [`usize`]
55///
56/// C header: [`include/linux/moduleparam.h`](srctree/include/linux/moduleparam.h)
57///
58/// [`Module`]: ../kernel/trait.Module.html
59///
60/// # Examples
61///
62/// ```
63/// use kernel::prelude::*;
64///
65/// module!{
66///     type: MyModule,
67///     name: "my_kernel_module",
68///     authors: ["Rust for Linux Contributors"],
69///     description: "My very own kernel module!",
70///     license: "GPL",
71///     alias: ["alternate_module_name"],
72///     params: {
73///         my_parameter: i64 {
74///             default: 1,
75///             description: "This parameter has a default of 1",
76///         },
77///     },
78/// }
79///
80/// struct MyModule(i32);
81///
82/// impl kernel::Module for MyModule {
83///     fn init(_module: &'static ThisModule) -> Result<Self> {
84///         let foo: i32 = 42;
85///         pr_info!("I contain:  {}\n", foo);
86///         pr_info!("i32 param is:  {}\n", module_parameters::my_parameter.read());
87///         Ok(Self(foo))
88///     }
89/// }
90/// # fn main() {}
91/// ```
92///
93/// ## Firmware
94///
95/// The following example shows how to declare a kernel module that needs
96/// to load binary firmware files. You need to specify the file names of
97/// the firmware in the `firmware` field. The information is embedded
98/// in the `modinfo` section of the kernel module. For example, a tool to
99/// build an initramfs uses this information to put the firmware files into
100/// the initramfs image.
101///
102/// ```
103/// use kernel::prelude::*;
104///
105/// module!{
106///     type: MyDeviceDriverModule,
107///     name: "my_device_driver_module",
108///     authors: ["Rust for Linux Contributors"],
109///     description: "My device driver requires firmware",
110///     license: "GPL",
111///     firmware: ["my_device_firmware1.bin", "my_device_firmware2.bin"],
112/// }
113///
114/// struct MyDeviceDriverModule;
115///
116/// impl kernel::Module for MyDeviceDriverModule {
117///     fn init(_module: &'static ThisModule) -> Result<Self> {
118///         Ok(Self)
119///     }
120/// }
121/// # fn main() {}
122/// ```
123///
124/// # Supported argument types
125///   - `type`: type which implements the [`Module`] trait (required).
126///   - `name`: ASCII string literal of the name of the kernel module (required).
127///   - `authors`: array of ASCII string literals of the authors of the kernel module.
128///   - `description`: string literal of the description of the kernel module.
129///   - `license`: ASCII string literal of the license of the kernel module (required).
130///   - `alias`: array of ASCII string literals of the alias names of the kernel module.
131///   - `firmware`: array of ASCII string literals of the firmware files of
132///     the kernel module.
133#[proc_macro]
134pub fn module(ts: TokenStream) -> TokenStream {
135    module::module(ts)
136}
137
138/// Declares or implements a vtable trait.
139///
140/// Linux's use of pure vtables is very close to Rust traits, but they differ
141/// in how unimplemented functions are represented. In Rust, traits can provide
142/// default implementation for all non-required methods (and the default
143/// implementation could just return `Error::EINVAL`); Linux typically use C
144/// `NULL` pointers to represent these functions.
145///
146/// This attribute closes that gap. A trait can be annotated with the
147/// `#[vtable]` attribute. Implementers of the trait will then also have to
148/// annotate the trait with `#[vtable]`. This attribute generates a `HAS_*`
149/// associated constant bool for each method in the trait that is set to true if
150/// the implementer has overridden the associated method.
151///
152/// For a trait method to be optional, it must have a default implementation.
153/// This is also the case for traits annotated with `#[vtable]`, but in this
154/// case the default implementation will never be executed. The reason for this
155/// is that the functions will be called through function pointers installed in
156/// C side vtables. When an optional method is not implemented on a `#[vtable]`
157/// trait, a NULL entry is installed in the vtable. Thus the default
158/// implementation is never called. Since these traits are not designed to be
159/// used on the Rust side, it should not be possible to call the default
160/// implementation. This is done to ensure that we call the vtable methods
161/// through the C vtable, and not through the Rust vtable. Therefore, the
162/// default implementation should call `build_error!`, which prevents
163/// calls to this function at compile time:
164///
165/// ```compile_fail
166/// # // Intentionally missing `use`s to simplify `rusttest`.
167/// build_error!(VTABLE_DEFAULT_ERROR)
168/// ```
169///
170/// Note that you might need to import [`kernel::error::VTABLE_DEFAULT_ERROR`].
171///
172/// This macro should not be used when all functions are required.
173///
174/// # Examples
175///
176/// ```
177/// use kernel::error::VTABLE_DEFAULT_ERROR;
178/// use kernel::prelude::*;
179///
180/// // Declares a `#[vtable]` trait
181/// #[vtable]
182/// pub trait Operations: Send + Sync + Sized {
183///     fn foo(&self) -> Result<()> {
184///         build_error!(VTABLE_DEFAULT_ERROR)
185///     }
186///
187///     fn bar(&self) -> Result<()> {
188///         build_error!(VTABLE_DEFAULT_ERROR)
189///     }
190/// }
191///
192/// struct Foo;
193///
194/// // Implements the `#[vtable]` trait
195/// #[vtable]
196/// impl Operations for Foo {
197///     fn foo(&self) -> Result<()> {
198/// #        Err(EINVAL)
199///         // ...
200///     }
201/// }
202///
203/// assert_eq!(<Foo as Operations>::HAS_FOO, true);
204/// assert_eq!(<Foo as Operations>::HAS_BAR, false);
205/// ```
206///
207/// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
208#[proc_macro_attribute]
209pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
210    vtable::vtable(attr, ts)
211}
212
213/// Export a function so that C code can call it via a header file.
214///
215/// Functions exported using this macro can be called from C code using the declaration in the
216/// appropriate header file. It should only be used in cases where C calls the function through a
217/// header file; cases where C calls into Rust via a function pointer in a vtable (such as
218/// `file_operations`) should not use this macro.
219///
220/// This macro has the following effect:
221///
222/// * Disables name mangling for this function.
223/// * Verifies at compile-time that the function signature matches the declaration in the header
224///   file.
225///
226/// You must declare the signature of the Rust function in a header file that is included by
227/// `rust/bindings/bindings_helper.h`.
228///
229/// This macro is *not* the same as the C macros `EXPORT_SYMBOL_*`. All Rust symbols are currently
230/// automatically exported with `EXPORT_SYMBOL_GPL`.
231#[proc_macro_attribute]
232pub fn export(attr: TokenStream, ts: TokenStream) -> TokenStream {
233    export::export(attr, ts)
234}
235
236/// Like [`core::format_args!`], but automatically wraps arguments in [`kernel::fmt::Adapter`].
237///
238/// This macro allows generating `fmt::Arguments` while ensuring that each argument is wrapped with
239/// `::kernel::fmt::Adapter`, which customizes formatting behavior for kernel logging.
240///
241/// Named arguments used in the format string (e.g. `{foo}`) are detected and resolved from local
242/// bindings. All positional and named arguments are automatically wrapped.
243///
244/// This macro is an implementation detail of other kernel logging macros like [`pr_info!`] and
245/// should not typically be used directly.
246///
247/// [`kernel::fmt::Adapter`]: ../kernel/fmt/struct.Adapter.html
248/// [`pr_info!`]: ../kernel/macro.pr_info.html
249#[proc_macro]
250pub fn fmt(input: TokenStream) -> TokenStream {
251    fmt::fmt(input)
252}
253
254/// Concatenate two identifiers.
255///
256/// This is useful in macros that need to declare or reference items with names
257/// starting with a fixed prefix and ending in a user specified name. The resulting
258/// identifier has the span of the second argument.
259///
260/// # Examples
261///
262/// ```
263/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
264/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
265/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
266/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
267/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
268/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
269/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
270/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
271/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
272/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
273/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
274/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
275/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
276/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
277/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
278/// use kernel::macros::concat_idents;
279///
280/// macro_rules! pub_no_prefix {
281///     ($prefix:ident, $($newname:ident),+) => {
282///         $(pub(crate) const $newname: u32 = concat_idents!($prefix, $newname);)+
283///     };
284/// }
285///
286/// pub_no_prefix!(
287///     binder_driver_return_protocol_,
288///     BR_OK,
289///     BR_ERROR,
290///     BR_TRANSACTION,
291///     BR_REPLY,
292///     BR_DEAD_REPLY,
293///     BR_TRANSACTION_COMPLETE,
294///     BR_INCREFS,
295///     BR_ACQUIRE,
296///     BR_RELEASE,
297///     BR_DECREFS,
298///     BR_NOOP,
299///     BR_SPAWN_LOOPER,
300///     BR_DEAD_BINDER,
301///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
302///     BR_FAILED_REPLY
303/// );
304///
305/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
306/// ```
307#[proc_macro]
308pub fn concat_idents(ts: TokenStream) -> TokenStream {
309    concat_idents::concat_idents(ts)
310}
311
312/// Paste identifiers together.
313///
314/// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
315/// single identifier.
316///
317/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
318/// literals (lifetimes and documentation strings are not supported). There is a difference in
319/// supported modifiers as well.
320///
321/// # Examples
322///
323/// ```
324/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
325/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
326/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
327/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
328/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
329/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
330/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
331/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
332/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
333/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
334/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
335/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
336/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
337/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
338/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
339/// macro_rules! pub_no_prefix {
340///     ($prefix:ident, $($newname:ident),+) => {
341///         ::kernel::macros::paste! {
342///             $(pub(crate) const $newname: u32 = [<$prefix $newname>];)+
343///         }
344///     };
345/// }
346///
347/// pub_no_prefix!(
348///     binder_driver_return_protocol_,
349///     BR_OK,
350///     BR_ERROR,
351///     BR_TRANSACTION,
352///     BR_REPLY,
353///     BR_DEAD_REPLY,
354///     BR_TRANSACTION_COMPLETE,
355///     BR_INCREFS,
356///     BR_ACQUIRE,
357///     BR_RELEASE,
358///     BR_DECREFS,
359///     BR_NOOP,
360///     BR_SPAWN_LOOPER,
361///     BR_DEAD_BINDER,
362///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
363///     BR_FAILED_REPLY
364/// );
365///
366/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
367/// ```
368///
369/// # Modifiers
370///
371/// For each identifier, it is possible to attach one or multiple modifiers to
372/// it.
373///
374/// Currently supported modifiers are:
375/// * `span`: change the span of concatenated identifier to the span of the specified token. By
376///   default the span of the `[< >]` group is used.
377/// * `lower`: change the identifier to lower case.
378/// * `upper`: change the identifier to upper case.
379///
380/// ```
381/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
382/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
383/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
384/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
385/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
386/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
387/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
388/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
389/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
390/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
391/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
392/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
393/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
394/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
395/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
396/// macro_rules! pub_no_prefix {
397///     ($prefix:ident, $($newname:ident),+) => {
398///         ::kernel::macros::paste! {
399///             $(pub(crate) const fn [<$newname:lower:span>]() -> u32 { [<$prefix $newname:span>] })+
400///         }
401///     };
402/// }
403///
404/// pub_no_prefix!(
405///     binder_driver_return_protocol_,
406///     BR_OK,
407///     BR_ERROR,
408///     BR_TRANSACTION,
409///     BR_REPLY,
410///     BR_DEAD_REPLY,
411///     BR_TRANSACTION_COMPLETE,
412///     BR_INCREFS,
413///     BR_ACQUIRE,
414///     BR_RELEASE,
415///     BR_DECREFS,
416///     BR_NOOP,
417///     BR_SPAWN_LOOPER,
418///     BR_DEAD_BINDER,
419///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
420///     BR_FAILED_REPLY
421/// );
422///
423/// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
424/// ```
425///
426/// # Literals
427///
428/// Literals can also be concatenated with other identifiers:
429///
430/// ```
431/// macro_rules! create_numbered_fn {
432///     ($name:literal, $val:literal) => {
433///         ::kernel::macros::paste! {
434///             fn [<some_ $name _fn $val>]() -> u32 { $val }
435///         }
436///     };
437/// }
438///
439/// create_numbered_fn!("foo", 100);
440///
441/// assert_eq!(some_foo_fn100(), 100)
442/// ```
443///
444/// [`paste`]: https://docs.rs/paste/
445#[proc_macro]
446pub fn paste(input: TokenStream) -> TokenStream {
447    let mut tokens = input.into_iter().collect();
448    paste::expand(&mut tokens);
449    tokens.into_iter().collect()
450}
451
452/// Registers a KUnit test suite and its test cases using a user-space like syntax.
453///
454/// This macro should be used on modules. If `CONFIG_KUNIT` (in `.config`) is `n`, the target module
455/// is ignored.
456///
457/// # Examples
458///
459/// ```ignore
460/// # use kernel::prelude::*;
461/// #[kunit_tests(kunit_test_suit_name)]
462/// mod tests {
463///     #[test]
464///     fn foo() {
465///         assert_eq!(1, 1);
466///     }
467///
468///     #[test]
469///     fn bar() {
470///         assert_eq!(2, 2);
471///     }
472/// }
473/// ```
474#[proc_macro_attribute]
475pub fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {
476    kunit::kunit_tests(attr, ts)
477}
macros/lib.rs

macros/
lib.rs
