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 1.87.0.
10#![feature(extract_if)]
11//
12// Stable since Rust 1.88.0 under a different name, `proc_macro_span_file`,
13// which was added in Rust 1.88.0. This is why `cfg_attr` is used here, i.e.
14// to avoid depending on the full `proc_macro_span` on Rust >= 1.88.0.
15#![cfg_attr(not(CONFIG_RUSTC_HAS_SPAN_FILE), feature(proc_macro_span))]
16
17mod concat_idents;
18mod export;
19mod fmt;
20mod for_lt;
21mod helpers;
22mod kunit;
23mod module;
24mod paste;
25mod vtable;
26
27use proc_macro::TokenStream;
28
29use syn::parse_macro_input;
30
31/// Declares a kernel module.
32///
33/// The `type` argument should be a type which implements the [`Module`]
34/// trait. Also accepts various forms of kernel metadata.
35///
36/// The `params` field describe module parameters. Each entry has the form
37///
38/// ```ignore
39/// parameter_name: type {
40///     default: default_value,
41///     description: "Description",
42/// }
43/// ```
44///
45/// `type` may be one of
46///
47/// - [`i8`]
48/// - [`u8`]
49/// - [`i8`]
50/// - [`u8`]
51/// - [`i16`]
52/// - [`u16`]
53/// - [`i32`]
54/// - [`u32`]
55/// - [`i64`]
56/// - [`u64`]
57/// - [`isize`]
58/// - [`usize`]
59/// - [`bool`]
60///
61/// C header: [`include/linux/moduleparam.h`](srctree/include/linux/moduleparam.h)
62///
63/// [`Module`]: ../kernel/trait.Module.html
64///
65/// # Examples
66///
67/// ```ignore
68/// use kernel::prelude::*;
69///
70/// module!{
71///     type: MyModule,
72///     name: "my_kernel_module",
73///     authors: ["Rust for Linux Contributors"],
74///     description: "My very own kernel module!",
75///     license: "GPL",
76///     alias: ["alternate_module_name"],
77///     params: {
78///         my_parameter: i64 {
79///             default: 1,
80///             description: "This parameter has a default of 1",
81///         },
82///     },
83/// }
84///
85/// struct MyModule(i32);
86///
87/// impl kernel::Module for MyModule {
88///     fn init(_module: &'static ThisModule) -> Result<Self> {
89///         let foo: i32 = 42;
90///         pr_info!("I contain:  {}\n", foo);
91///         pr_info!("i32 param is:  {}\n", module_parameters::my_parameter.read());
92///         Ok(Self(foo))
93///     }
94/// }
95/// # fn main() {}
96/// ```
97///
98/// ## Firmware
99///
100/// The following example shows how to declare a kernel module that needs
101/// to load binary firmware files. You need to specify the file names of
102/// the firmware in the `firmware` field. The information is embedded
103/// in the `modinfo` section of the kernel module. For example, a tool to
104/// build an initramfs uses this information to put the firmware files into
105/// the initramfs image.
106///
107/// ```
108/// use kernel::prelude::*;
109///
110/// module!{
111///     type: MyDeviceDriverModule,
112///     name: "my_device_driver_module",
113///     authors: ["Rust for Linux Contributors"],
114///     description: "My device driver requires firmware",
115///     license: "GPL",
116///     firmware: ["my_device_firmware1.bin", "my_device_firmware2.bin"],
117/// }
118///
119/// struct MyDeviceDriverModule;
120///
121/// impl kernel::Module for MyDeviceDriverModule {
122///     fn init(_module: &'static ThisModule) -> Result<Self> {
123///         Ok(Self)
124///     }
125/// }
126/// # fn main() {}
127/// ```
128///
129/// # Supported argument types
130///   - `type`: type which implements the [`Module`] trait (required).
131///   - `name`: ASCII string literal of the name of the kernel module (required).
132///   - `authors`: array of ASCII string literals of the authors of the kernel module.
133///   - `description`: string literal of the description of the kernel module.
134///   - `license`: ASCII string literal of the license of the kernel module (required).
135///   - `alias`: array of ASCII string literals of the alias names of the kernel module.
136///   - `firmware`: array of ASCII string literals of the firmware files of
137///     the kernel module.
138#[proc_macro]
139pub fn module(input: TokenStream) -> TokenStream {
140    module::module(parse_macro_input!(input))
141        .unwrap_or_else(|e| e.into_compile_error())
142        .into()
143}
144
145/// Declares or implements a vtable trait.
146///
147/// Linux's use of pure vtables is very close to Rust traits, but they differ
148/// in how unimplemented functions are represented. In Rust, traits can provide
149/// default implementation for all non-required methods (and the default
150/// implementation could just return `Error::EINVAL`); Linux typically use C
151/// `NULL` pointers to represent these functions.
152///
153/// This attribute closes that gap. A trait can be annotated with the
154/// `#[vtable]` attribute. Implementers of the trait will then also have to
155/// annotate the trait with `#[vtable]`. This attribute generates a `HAS_*`
156/// associated constant bool for each method in the trait that is set to true if
157/// the implementer has overridden the associated method.
158///
159/// For a trait method to be optional, it must have a default implementation.
160/// This is also the case for traits annotated with `#[vtable]`, but in this
161/// case the default implementation will never be executed. The reason for this
162/// is that the functions will be called through function pointers installed in
163/// C side vtables. When an optional method is not implemented on a `#[vtable]`
164/// trait, a `NULL` entry is installed in the vtable. Thus the default
165/// implementation is never called. Since these traits are not designed to be
166/// used on the Rust side, it should not be possible to call the default
167/// implementation. This is done to ensure that we call the vtable methods
168/// through the C vtable, and not through the Rust vtable. Therefore, the
169/// default implementation should call `build_error!`, which prevents
170/// calls to this function at compile time:
171///
172/// ```compile_fail
173/// # // Intentionally missing `use`s to simplify `rusttest`.
174/// build_error!(VTABLE_DEFAULT_ERROR)
175/// ```
176///
177/// Note that you might need to import [`kernel::error::VTABLE_DEFAULT_ERROR`].
178///
179/// This macro should not be used when all functions are required.
180///
181/// Additionally, this macro automatically handles the `OwnerModule`
182/// associated type: on the trait side, `type OwnerModule: ModuleMetadata;`
183/// is added as a required associated type if not already defined; on the
184/// impl side, `type OwnerModule = LocalModule;` is automatically inserted
185/// if not explicitly defined.
186///
187/// # Examples
188///
189/// ```
190/// use kernel::error::VTABLE_DEFAULT_ERROR;
191/// use kernel::prelude::*;
192///
193/// # struct LocalModule;
194/// # impl kernel::ModuleMetadata for LocalModule {
195/// #     const NAME: &'static kernel::str::CStr = c"vtable_doctest";
196/// #
197/// #     // SAFETY: This doctest runs on the host: there is no `THIS_MODULE`.
198/// #     const THIS_MODULE: kernel::ThisModule = unsafe {
199/// #         kernel::ThisModule::from_ptr(core::ptr::null_mut())
200/// #     };
201/// # }
202/// #
203/// # fn main() {
204/// // Declares a `#[vtable]` trait
205/// #[vtable]
206/// pub trait Operations: Send + Sync + Sized {
207///     fn foo(&self) -> Result<()> {
208///         build_error!(VTABLE_DEFAULT_ERROR)
209///     }
210///
211///     fn bar(&self) -> Result<()> {
212///         build_error!(VTABLE_DEFAULT_ERROR)
213///     }
214/// }
215///
216/// struct Foo;
217///
218/// // Implements the `#[vtable]` trait
219/// #[vtable]
220/// impl Operations for Foo {
221///     fn foo(&self) -> Result<()> {
222/// #        Err(EINVAL)
223///         // ...
224///     }
225/// }
226///
227/// assert_eq!(<Foo as Operations>::HAS_FOO, true);
228/// assert_eq!(<Foo as Operations>::HAS_BAR, false);
229/// # }
230/// ```
231///
232/// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
233#[proc_macro_attribute]
234pub fn vtable(attr: TokenStream, input: TokenStream) -> TokenStream {
235    parse_macro_input!(attr as syn::parse::Nothing);
236    vtable::vtable(parse_macro_input!(input))
237        .unwrap_or_else(|e| e.into_compile_error())
238        .into()
239}
240
241/// Export a function so that C code can call it via a header file.
242///
243/// Functions exported using this macro can be called from C code using the declaration in the
244/// appropriate header file. It should only be used in cases where C calls the function through a
245/// header file; cases where C calls into Rust via a function pointer in a vtable (such as
246/// `file_operations`) should not use this macro.
247///
248/// This macro has the following effect:
249///
250/// * Disables name mangling for this function.
251/// * Verifies at compile-time that the function signature matches the declaration in the header
252///   file.
253///
254/// You must declare the signature of the Rust function in a header file that is included by
255/// `rust/bindings/bindings_helper.h`.
256///
257/// This macro is *not* the same as the C macros `EXPORT_SYMBOL_*`. All Rust symbols are currently
258/// automatically exported with `EXPORT_SYMBOL_GPL`.
259#[proc_macro_attribute]
260pub fn export(attr: TokenStream, input: TokenStream) -> TokenStream {
261    parse_macro_input!(attr as syn::parse::Nothing);
262    export::export(parse_macro_input!(input)).into()
263}
264
265/// Like [`core::format_args!`], but automatically wraps arguments in [`kernel::fmt::Adapter`].
266///
267/// This macro allows generating `fmt::Arguments` while ensuring that each argument is wrapped with
268/// `::kernel::fmt::Adapter`, which customizes formatting behavior for kernel logging.
269///
270/// Named arguments used in the format string (e.g. `{foo}`) are detected and resolved from local
271/// bindings. All positional and named arguments are automatically wrapped.
272///
273/// This macro is an implementation detail of other kernel logging macros like [`pr_info!`] and
274/// should not typically be used directly.
275///
276/// [`kernel::fmt::Adapter`]: ../kernel/fmt/struct.Adapter.html
277/// [`pr_info!`]: ../kernel/macro.pr_info.html
278#[proc_macro]
279pub fn fmt(input: TokenStream) -> TokenStream {
280    fmt::fmt(input.into()).into()
281}
282
283/// Concatenate two identifiers.
284///
285/// This is useful in macros that need to declare or reference items with names
286/// starting with a fixed prefix and ending in a user specified name. The resulting
287/// identifier has the span of the second argument.
288///
289/// # Examples
290///
291/// ```
292/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
293/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
294/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
295/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
296/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
297/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
298/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
299/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
300/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
301/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
302/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
303/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
304/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
305/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
306/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
307/// use kernel::macros::concat_idents;
308///
309/// macro_rules! pub_no_prefix {
310///     ($prefix:ident, $($newname:ident),+) => {
311///         $(pub(crate) const $newname: u32 = concat_idents!($prefix, $newname);)+
312///     };
313/// }
314///
315/// pub_no_prefix!(
316///     binder_driver_return_protocol_,
317///     BR_OK,
318///     BR_ERROR,
319///     BR_TRANSACTION,
320///     BR_REPLY,
321///     BR_DEAD_REPLY,
322///     BR_TRANSACTION_COMPLETE,
323///     BR_INCREFS,
324///     BR_ACQUIRE,
325///     BR_RELEASE,
326///     BR_DECREFS,
327///     BR_NOOP,
328///     BR_SPAWN_LOOPER,
329///     BR_DEAD_BINDER,
330///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
331///     BR_FAILED_REPLY
332/// );
333///
334/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
335/// ```
336#[proc_macro]
337pub fn concat_idents(input: TokenStream) -> TokenStream {
338    concat_idents::concat_idents(parse_macro_input!(input)).into()
339}
340
341/// Paste identifiers together.
342///
343/// Within the `paste!` macro, identifiers inside `[<` and `>]` are concatenated together to form a
344/// single identifier.
345///
346/// This is similar to the [`paste`] crate, but with pasting feature limited to identifiers and
347/// literals (lifetimes and documentation strings are not supported). There is a difference in
348/// supported modifiers as well.
349///
350/// # Examples
351///
352/// ```
353/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
354/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
355/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
356/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
357/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
358/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
359/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
360/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
361/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
362/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
363/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
364/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
365/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
366/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
367/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
368/// macro_rules! pub_no_prefix {
369///     ($prefix:ident, $($newname:ident),+) => {
370///         ::kernel::macros::paste! {
371///             $(pub(crate) const $newname: u32 = [<$prefix $newname>];)+
372///         }
373///     };
374/// }
375///
376/// pub_no_prefix!(
377///     binder_driver_return_protocol_,
378///     BR_OK,
379///     BR_ERROR,
380///     BR_TRANSACTION,
381///     BR_REPLY,
382///     BR_DEAD_REPLY,
383///     BR_TRANSACTION_COMPLETE,
384///     BR_INCREFS,
385///     BR_ACQUIRE,
386///     BR_RELEASE,
387///     BR_DECREFS,
388///     BR_NOOP,
389///     BR_SPAWN_LOOPER,
390///     BR_DEAD_BINDER,
391///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
392///     BR_FAILED_REPLY
393/// );
394///
395/// assert_eq!(BR_OK, binder_driver_return_protocol_BR_OK);
396/// ```
397///
398/// # Modifiers
399///
400/// For each identifier, it is possible to attach one or multiple modifiers to
401/// it.
402///
403/// Currently supported modifiers are:
404/// * `span`: change the span of concatenated identifier to the span of the specified token. By
405///   default the span of the `[< >]` group is used.
406/// * `lower`: change the identifier to lower case.
407/// * `upper`: change the identifier to upper case.
408///
409/// ```
410/// # const binder_driver_return_protocol_BR_OK: u32 = 0;
411/// # const binder_driver_return_protocol_BR_ERROR: u32 = 1;
412/// # const binder_driver_return_protocol_BR_TRANSACTION: u32 = 2;
413/// # const binder_driver_return_protocol_BR_REPLY: u32 = 3;
414/// # const binder_driver_return_protocol_BR_DEAD_REPLY: u32 = 4;
415/// # const binder_driver_return_protocol_BR_TRANSACTION_COMPLETE: u32 = 5;
416/// # const binder_driver_return_protocol_BR_INCREFS: u32 = 6;
417/// # const binder_driver_return_protocol_BR_ACQUIRE: u32 = 7;
418/// # const binder_driver_return_protocol_BR_RELEASE: u32 = 8;
419/// # const binder_driver_return_protocol_BR_DECREFS: u32 = 9;
420/// # const binder_driver_return_protocol_BR_NOOP: u32 = 10;
421/// # const binder_driver_return_protocol_BR_SPAWN_LOOPER: u32 = 11;
422/// # const binder_driver_return_protocol_BR_DEAD_BINDER: u32 = 12;
423/// # const binder_driver_return_protocol_BR_CLEAR_DEATH_NOTIFICATION_DONE: u32 = 13;
424/// # const binder_driver_return_protocol_BR_FAILED_REPLY: u32 = 14;
425/// macro_rules! pub_no_prefix {
426///     ($prefix:ident, $($newname:ident),+) => {
427///         ::kernel::macros::paste! {
428///             $(pub(crate) const fn [<$newname:lower:span>]() -> u32 { [<$prefix $newname:span>] })+
429///         }
430///     };
431/// }
432///
433/// pub_no_prefix!(
434///     binder_driver_return_protocol_,
435///     BR_OK,
436///     BR_ERROR,
437///     BR_TRANSACTION,
438///     BR_REPLY,
439///     BR_DEAD_REPLY,
440///     BR_TRANSACTION_COMPLETE,
441///     BR_INCREFS,
442///     BR_ACQUIRE,
443///     BR_RELEASE,
444///     BR_DECREFS,
445///     BR_NOOP,
446///     BR_SPAWN_LOOPER,
447///     BR_DEAD_BINDER,
448///     BR_CLEAR_DEATH_NOTIFICATION_DONE,
449///     BR_FAILED_REPLY
450/// );
451///
452/// assert_eq!(br_ok(), binder_driver_return_protocol_BR_OK);
453/// ```
454///
455/// # Literals
456///
457/// Literals can also be concatenated with other identifiers:
458///
459/// ```
460/// macro_rules! create_numbered_fn {
461///     ($name:literal, $val:literal) => {
462///         ::kernel::macros::paste! {
463///             fn [<some_ $name _fn $val>]() -> u32 { $val }
464///         }
465///     };
466/// }
467///
468/// create_numbered_fn!("foo", 100);
469///
470/// assert_eq!(some_foo_fn100(), 100)
471/// ```
472///
473/// [`paste`]: https://docs.rs/paste/
474#[proc_macro]
475pub fn paste(input: TokenStream) -> TokenStream {
476    let mut tokens = proc_macro2::TokenStream::from(input).into_iter().collect();
477    paste::expand(&mut tokens);
478    tokens
479        .into_iter()
480        .collect::<proc_macro2::TokenStream>()
481        .into()
482}
483
484/// Registers a KUnit test suite and its test cases using a user-space like syntax.
485///
486/// This macro should be used on modules. If `CONFIG_KUNIT` (in `.config`) is `n`, the target module
487/// is ignored.
488///
489/// # Examples
490///
491/// ```ignore
492/// # use kernel::prelude::*;
493/// #[kunit_tests(kunit_test_suit_name)]
494/// mod tests {
495///     #[test]
496///     fn foo() {
497///         assert_eq!(1, 1);
498///     }
499///
500///     #[test]
501///     fn bar() {
502///         assert_eq!(2, 2);
503///     }
504/// }
505/// ```
506#[proc_macro_attribute]
507pub fn kunit_tests(attr: TokenStream, input: TokenStream) -> TokenStream {
508    kunit::kunit_tests(parse_macro_input!(attr), parse_macro_input!(input))
509        .unwrap_or_else(|e| e.into_compile_error())
510        .into()
511}
512
513/// Obtain a type that implements [`ForLt`] for the given higher-ranked type.
514///
515/// Please refer to the documentation of the [`ForLt`] trait.
516///
517/// [`ForLt`]: trait.ForLt.html
518#[proc_macro]
519#[allow(non_snake_case)]
520pub fn ForLt(input: TokenStream) -> TokenStream {
521    for_lt::for_lt(parse_macro_input!(input)).into()
522}
523
524/// Obtain a type that implements [`CovariantForLt`] (and [`ForLt`]) for the given higher-ranked
525/// type.
526///
527/// Unlike [`ForLt!`], this macro additionally proves that the type is covariant over the lifetime,
528/// providing a safe [`CovariantForLt::cast_ref`] method.
529///
530/// Please refer to the documentation of the [`CovariantForLt`] trait.
531///
532/// [`CovariantForLt`]: trait.CovariantForLt.html
533/// [`CovariantForLt::cast_ref`]: trait.CovariantForLt.html#method.cast_ref
534/// [`ForLt`]: trait.ForLt.html
535#[proc_macro]
536#[allow(non_snake_case)]
537pub fn CovariantForLt(input: TokenStream) -> TokenStream {
538    for_lt::covariant_for_lt(parse_macro_input!(input)).into()
539}
macros/lib.rs

macros/
lib.rs
