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
14mod concat_idents;
15mod export;
16mod fmt;
17mod helpers;
18mod kunit;
19mod module;
20mod paste;
21mod vtable;
22
23use proc_macro::TokenStream;
24
25use syn::parse_macro_input;
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/// ```ignore
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(input: TokenStream) -> TokenStream {
135    module::module(parse_macro_input!(input))
136        .unwrap_or_else(|e| e.into_compile_error())
137        .into()
138}
139
140/// Declares or implements a vtable trait.
141///
142/// Linux's use of pure vtables is very close to Rust traits, but they differ
143/// in how unimplemented functions are represented. In Rust, traits can provide
144/// default implementation for all non-required methods (and the default
145/// implementation could just return `Error::EINVAL`); Linux typically use C
146/// `NULL` pointers to represent these functions.
147///
148/// This attribute closes that gap. A trait can be annotated with the
149/// `#[vtable]` attribute. Implementers of the trait will then also have to
150/// annotate the trait with `#[vtable]`. This attribute generates a `HAS_*`
151/// associated constant bool for each method in the trait that is set to true if
152/// the implementer has overridden the associated method.
153///
154/// For a trait method to be optional, it must have a default implementation.
155/// This is also the case for traits annotated with `#[vtable]`, but in this
156/// case the default implementation will never be executed. The reason for this
157/// is that the functions will be called through function pointers installed in
158/// C side vtables. When an optional method is not implemented on a `#[vtable]`
159/// trait, a `NULL` entry is installed in the vtable. Thus the default
160/// implementation is never called. Since these traits are not designed to be
161/// used on the Rust side, it should not be possible to call the default
162/// implementation. This is done to ensure that we call the vtable methods
163/// through the C vtable, and not through the Rust vtable. Therefore, the
164/// default implementation should call `build_error!`, which prevents
165/// calls to this function at compile time:
166///
167/// ```compile_fail
168/// # // Intentionally missing `use`s to simplify `rusttest`.
169/// build_error!(VTABLE_DEFAULT_ERROR)
170/// ```
171///
172/// Note that you might need to import [`kernel::error::VTABLE_DEFAULT_ERROR`].
173///
174/// This macro should not be used when all functions are required.
175///
176/// # Examples
177///
178/// ```
179/// use kernel::error::VTABLE_DEFAULT_ERROR;
180/// use kernel::prelude::*;
181///
182/// // Declares a `#[vtable]` trait
183/// #[vtable]
184/// pub trait Operations: Send + Sync + Sized {
185///     fn foo(&self) -> Result<()> {
186///         build_error!(VTABLE_DEFAULT_ERROR)
187///     }
188///
189///     fn bar(&self) -> Result<()> {
190///         build_error!(VTABLE_DEFAULT_ERROR)
191///     }
192/// }
193///
194/// struct Foo;
195///
196/// // Implements the `#[vtable]` trait
197/// #[vtable]
198/// impl Operations for Foo {
199///     fn foo(&self) -> Result<()> {
200/// #        Err(EINVAL)
201///         // ...
202///     }
203/// }
204///
205/// assert_eq!(<Foo as Operations>::HAS_FOO, true);
206/// assert_eq!(<Foo as Operations>::HAS_BAR, false);
207/// ```
208///
209/// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
210#[proc_macro_attribute]
211pub fn vtable(attr: TokenStream, input: TokenStream) -> TokenStream {
212    parse_macro_input!(attr as syn::parse::Nothing);
213    vtable::vtable(parse_macro_input!(input))
214        .unwrap_or_else(|e| e.into_compile_error())
215        .into()
216}
217
218/// Export a function so that C code can call it via a header file.
219///
220/// Functions exported using this macro can be called from C code using the declaration in the
221/// appropriate header file. It should only be used in cases where C calls the function through a
222/// header file; cases where C calls into Rust via a function pointer in a vtable (such as
223/// `file_operations`) should not use this macro.
224///
225/// This macro has the following effect:
226///
227/// * Disables name mangling for this function.
228/// * Verifies at compile-time that the function signature matches the declaration in the header
229///   file.
230///
231/// You must declare the signature of the Rust function in a header file that is included by
232/// `rust/bindings/bindings_helper.h`.
233///
234/// This macro is *not* the same as the C macros `EXPORT_SYMBOL_*`. All Rust symbols are currently
235/// automatically exported with `EXPORT_SYMBOL_GPL`.
236#[proc_macro_attribute]
237pub fn export(attr: TokenStream, input: TokenStream) -> TokenStream {
238    parse_macro_input!(attr as syn::parse::Nothing);
239    export::export(parse_macro_input!(input)).into()
240}
241
242/// Like [`core::format_args!`], but automatically wraps arguments in [`kernel::fmt::Adapter`].
243///
244/// This macro allows generating `fmt::Arguments` while ensuring that each argument is wrapped with
245/// `::kernel::fmt::Adapter`, which customizes formatting behavior for kernel logging.
246///
247/// Named arguments used in the format string (e.g. `{foo}`) are detected and resolved from local
248/// bindings. All positional and named arguments are automatically wrapped.
249///
250/// This macro is an implementation detail of other kernel logging macros like [`pr_info!`] and
251/// should not typically be used directly.
252///
253/// [`kernel::fmt::Adapter`]: ../kernel/fmt/struct.Adapter.html
254/// [`pr_info!`]: ../kernel/macro.pr_info.html
255#[proc_macro]
256pub fn fmt(input: TokenStream) -> TokenStream {
257    fmt::fmt(input.into()).into()
258}
259
260/// Concatenate two identifiers.
261///
262/// This is useful in macros that need to declare or reference items with names
263/// starting with a fixed prefix and ending in a user specified name. The resulting
264/// identifier has the span of the second argument.
265///
266/// # Examples
267///
268/// ```
269/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
270/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
271/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
272/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
273/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
274/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
275/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
276/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
277/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
278/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
279/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
280/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
281/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
282/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
283/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
284/// use kernel::macros::concat_idents;
285///
286/// macro_rules! pub_no_prefix {
287///     ($prefix:ident, $($newname:ident),+) => {
288///         $(pub(crate) const $newname: u32 = concat_idents!($prefix, $newname);)+
289///     };
290/// }
291///
292/// pub_no_prefix!(
293///     binder_driver_return_protocol_,
294///     BR_OK,
295///     BR_ERROR,
296///     BR_TRANSACTION,
297///     BR_REPLY,
298///     BR_DEAD_REPLY,
299///     BR_TRANSACTION_COMPLETE,
300///     BR_INCREFS,
301///     BR_ACQUIRE,
302///     BR_RELEASE,
303///     BR_DECREFS,
304///     BR_NOOP,
305///     BR_SPAWN_LOOPER,
306///     BR_DEAD_BINDER,
307///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
308///     BR_FAILED_REPLY
309/// );
310///
311/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
312/// ```
313#[proc_macro]
314pub fn concat_idents(input: TokenStream) -> TokenStream {
315    concat_idents::concat_idents(parse_macro_input!(input)).into()
316}
317
318/// Paste identifiers together.
319///
320/// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
321/// single identifier.
322///
323/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
324/// literals (lifetimes and documentation strings are not supported). There is a difference in
325/// supported modifiers as well.
326///
327/// # Examples
328///
329/// ```
330/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
331/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
332/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
333/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
334/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
335/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
336/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
337/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
338/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
339/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
340/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
341/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
342/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
343/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
344/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
345/// macro_rules! pub_no_prefix {
346///     ($prefix:ident, $($newname:ident),+) => {
347///         ::kernel::macros::paste! {
348///             $(pub(crate) const $newname: u32 = [<$prefix $newname>];)+
349///         }
350///     };
351/// }
352///
353/// pub_no_prefix!(
354///     binder_driver_return_protocol_,
355///     BR_OK,
356///     BR_ERROR,
357///     BR_TRANSACTION,
358///     BR_REPLY,
359///     BR_DEAD_REPLY,
360///     BR_TRANSACTION_COMPLETE,
361///     BR_INCREFS,
362///     BR_ACQUIRE,
363///     BR_RELEASE,
364///     BR_DECREFS,
365///     BR_NOOP,
366///     BR_SPAWN_LOOPER,
367///     BR_DEAD_BINDER,
368///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
369///     BR_FAILED_REPLY
370/// );
371///
372/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
373/// ```
374///
375/// # Modifiers
376///
377/// For each identifier, it is possible to attach one or multiple modifiers to
378/// it.
379///
380/// Currently supported modifiers are:
381/// * `span`: change the span of concatenated identifier to the span of the specified token. By
382///   default the span of the `[< >]` group is used.
383/// * `lower`: change the identifier to lower case.
384/// * `upper`: change the identifier to upper case.
385///
386/// ```
387/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
388/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
389/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
390/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
391/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
392/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
393/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
394/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
395/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
396/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
397/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
398/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
399/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
400/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
401/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
402/// macro_rules! pub_no_prefix {
403///     ($prefix:ident, $($newname:ident),+) => {
404///         ::kernel::macros::paste! {
405///             $(pub(crate) const fn [<$newname:lower:span>]() -> u32 { [<$prefix $newname:span>] })+
406///         }
407///     };
408/// }
409///
410/// pub_no_prefix!(
411///     binder_driver_return_protocol_,
412///     BR_OK,
413///     BR_ERROR,
414///     BR_TRANSACTION,
415///     BR_REPLY,
416///     BR_DEAD_REPLY,
417///     BR_TRANSACTION_COMPLETE,
418///     BR_INCREFS,
419///     BR_ACQUIRE,
420///     BR_RELEASE,
421///     BR_DECREFS,
422///     BR_NOOP,
423///     BR_SPAWN_LOOPER,
424///     BR_DEAD_BINDER,
425///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
426///     BR_FAILED_REPLY
427/// );
428///
429/// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
430/// ```
431///
432/// # Literals
433///
434/// Literals can also be concatenated with other identifiers:
435///
436/// ```
437/// macro_rules! create_numbered_fn {
438///     ($name:literal, $val:literal) => {
439///         ::kernel::macros::paste! {
440///             fn [<some_ $name _fn $val>]() -> u32 { $val }
441///         }
442///     };
443/// }
444///
445/// create_numbered_fn!("foo", 100);
446///
447/// assert_eq!(some_foo_fn100(), 100)
448/// ```
449///
450/// [`paste`]: https://docs.rs/paste/
451#[proc_macro]
452pub fn paste(input: TokenStream) -> TokenStream {
453    let mut tokens = proc_macro2::TokenStream::from(input).into_iter().collect();
454    paste::expand(&mut tokens);
455    tokens
456        .into_iter()
457        .collect::<proc_macro2::TokenStream>()
458        .into()
459}
460
461/// Registers a KUnit test suite and its test cases using a user-space like syntax.
462///
463/// This macro should be used on modules. If `CONFIG_KUNIT` (in `.config`) is `n`, the target module
464/// is ignored.
465///
466/// # Examples
467///
468/// ```ignore
469/// # use kernel::prelude::*;
470/// #[kunit_tests(kunit_test_suit_name)]
471/// mod tests {
472///     #[test]
473///     fn foo() {
474///         assert_eq!(1, 1);
475///     }
476///
477///     #[test]
478///     fn bar() {
479///         assert_eq!(2, 2);
480///     }
481/// }
482/// ```
483#[proc_macro_attribute]
484pub fn kunit_tests(attr: TokenStream, input: TokenStream) -> TokenStream {
485    kunit::kunit_tests(parse_macro_input!(attr), parse_macro_input!(input))
486        .unwrap_or_else(|e| e.into_compile_error())
487        .into()
488}
macros/lib.rs

macros/
lib.rs
