kernel/
lib.rs

1// SPDX-License-Identifier: GPL-2.0
2
3//! The `kernel` crate.
4//!
5//! This crate contains the kernel APIs that have been ported or wrapped for
6//! usage by Rust code in the kernel and is shared by all of them.
7//!
8//! In other words, all the rest of the Rust code in the kernel (e.g. kernel
9//! modules written in Rust) depends on [`core`] and this crate.
10//!
11//! If you need a kernel C API that is not ported or wrapped yet here, then
12//! do so first instead of bypassing this crate.
13
14#![no_std]
15//
16// Please see https://github.com/Rust-for-Linux/linux/issues/2 for details on
17// the unstable features in use.
18//
19// Stable since Rust 1.79.0.
20#![feature(inline_const)]
21//
22// Stable since Rust 1.81.0.
23#![feature(lint_reasons)]
24//
25// Stable since Rust 1.82.0.
26#![feature(raw_ref_op)]
27//
28// Stable since Rust 1.83.0.
29#![feature(const_maybe_uninit_as_mut_ptr)]
30#![feature(const_mut_refs)]
31#![feature(const_ptr_write)]
32#![feature(const_refs_to_cell)]
33//
34// Expected to become stable.
35#![feature(arbitrary_self_types)]
36//
37// `feature(derive_coerce_pointee)` is expected to become stable. Before Rust
38// 1.84.0, it did not exist, so enable the predecessor features.
39#![cfg_attr(CONFIG_RUSTC_HAS_COERCE_POINTEE, feature(derive_coerce_pointee))]
40#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(coerce_unsized))]
41#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(dispatch_from_dyn))]
42#![cfg_attr(not(CONFIG_RUSTC_HAS_COERCE_POINTEE), feature(unsize))]
43
44// Ensure conditional compilation based on the kernel configuration works;
45// otherwise we may silently break things like initcall handling.
46#[cfg(not(CONFIG_RUST))]
47compile_error!("Missing kernel configuration for conditional compilation");
48
49// Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
50extern crate self as kernel;
51
52pub use ffi;
53
54pub mod alloc;
55#[cfg(CONFIG_AUXILIARY_BUS)]
56pub mod auxiliary;
57#[cfg(CONFIG_BLOCK)]
58pub mod block;
59#[doc(hidden)]
60pub mod build_assert;
61pub mod clk;
62#[cfg(CONFIG_CONFIGFS_FS)]
63pub mod configfs;
64pub mod cpu;
65#[cfg(CONFIG_CPU_FREQ)]
66pub mod cpufreq;
67pub mod cpumask;
68pub mod cred;
69pub mod device;
70pub mod device_id;
71pub mod devres;
72pub mod dma;
73pub mod driver;
74#[cfg(CONFIG_DRM = "y")]
75pub mod drm;
76pub mod error;
77pub mod faux;
78#[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]
79pub mod firmware;
80pub mod fs;
81pub mod init;
82pub mod io;
83pub mod ioctl;
84pub mod jump_label;
85#[cfg(CONFIG_KUNIT)]
86pub mod kunit;
87pub mod list;
88pub mod miscdevice;
89pub mod mm;
90#[cfg(CONFIG_NET)]
91pub mod net;
92pub mod of;
93#[cfg(CONFIG_PM_OPP)]
94pub mod opp;
95pub mod page;
96#[cfg(CONFIG_PCI)]
97pub mod pci;
98pub mod pid_namespace;
99pub mod platform;
100pub mod prelude;
101pub mod print;
102pub mod rbtree;
103pub mod revocable;
104pub mod security;
105pub mod seq_file;
106pub mod sizes;
107mod static_assert;
108#[doc(hidden)]
109pub mod std_vendor;
110pub mod str;
111pub mod sync;
112pub mod task;
113pub mod time;
114pub mod tracepoint;
115pub mod transmute;
116pub mod types;
117pub mod uaccess;
118pub mod workqueue;
119pub mod xarray;
120
121#[doc(hidden)]
122pub use bindings;
123pub use macros;
124pub use uapi;
125
126/// Prefix to appear before log messages printed from within the `kernel` crate.
127const __LOG_PREFIX: &[u8] = b"rust_kernel\0";
128
129/// The top level entrypoint to implementing a kernel module.
130///
131/// For any teardown or cleanup operations, your type may implement [`Drop`].
132pub trait Module: Sized + Sync + Send {
133    /// Called at module initialization time.
134    ///
135    /// Use this method to perform whatever setup or registration your module
136    /// should do.
137    ///
138    /// Equivalent to the `module_init` macro in the C API.
139    fn init(module: &'static ThisModule) -> error::Result<Self>;
140}
141
142/// A module that is pinned and initialised in-place.
143pub trait InPlaceModule: Sync + Send {
144    /// Creates an initialiser for the module.
145    ///
146    /// It is called when the module is loaded.
147    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, error::Error>;
148}
149
150impl<T: Module> InPlaceModule for T {
151    fn init(module: &'static ThisModule) -> impl pin_init::PinInit<Self, error::Error> {
152        let initer = move |slot: *mut Self| {
153            let m = <Self as Module>::init(module)?;
154
155            // SAFETY: `slot` is valid for write per the contract with `pin_init_from_closure`.
156            unsafe { slot.write(m) };
157            Ok(())
158        };
159
160        // SAFETY: On success, `initer` always fully initialises an instance of `Self`.
161        unsafe { pin_init::pin_init_from_closure(initer) }
162    }
163}
164
165/// Metadata attached to a [`Module`] or [`InPlaceModule`].
166pub trait ModuleMetadata {
167    /// The name of the module as specified in the `module!` macro.
168    const NAME: &'static crate::str::CStr;
169}
170
171/// Equivalent to `THIS_MODULE` in the C API.
172///
173/// C header: [`include/linux/init.h`](srctree/include/linux/init.h)
174pub struct ThisModule(*mut bindings::module);
175
176// SAFETY: `THIS_MODULE` may be used from all threads within a module.
177unsafe impl Sync for ThisModule {}
178
179impl ThisModule {
180    /// Creates a [`ThisModule`] given the `THIS_MODULE` pointer.
181    ///
182    /// # Safety
183    ///
184    /// The pointer must be equal to the right `THIS_MODULE`.
185    pub const unsafe fn from_ptr(ptr: *mut bindings::module) -> ThisModule {
186        ThisModule(ptr)
187    }
188
189    /// Access the raw pointer for this module.
190    ///
191    /// It is up to the user to use it correctly.
192    pub const fn as_ptr(&self) -> *mut bindings::module {
193        self.0
194    }
195}
196
197#[cfg(not(any(testlib, test)))]
198#[panic_handler]
199fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
200    pr_emerg!("{}\n", info);
201    // SAFETY: FFI call.
202    unsafe { bindings::BUG() };
203}
204
205/// Produces a pointer to an object from a pointer to one of its fields.
206///
207/// # Safety
208///
209/// The pointer passed to this macro, and the pointer returned by this macro, must both be in
210/// bounds of the same allocation.
211///
212/// # Examples
213///
214/// ```
215/// # use kernel::container_of;
216/// struct Test {
217///     a: u64,
218///     b: u32,
219/// }
220///
221/// let test = Test { a: 10, b: 20 };
222/// let b_ptr: *const _ = &test.b;
223/// // SAFETY: The pointer points at the `b` field of a `Test`, so the resulting pointer will be
224/// // in-bounds of the same allocation as `b_ptr`.
225/// let test_alias = unsafe { container_of!(b_ptr, Test, b) };
226/// assert!(core::ptr::eq(&test, test_alias));
227/// ```
228#[macro_export]
229macro_rules! container_of {
230    ($field_ptr:expr, $Container:ty, $($fields:tt)*) => {{
231        let offset: usize = ::core::mem::offset_of!($Container, $($fields)*);
232        let field_ptr = $field_ptr;
233        let container_ptr = field_ptr.byte_sub(offset).cast::<$Container>();
234        $crate::assert_same_type(field_ptr, (&raw const (*container_ptr).$($fields)*).cast_mut());
235        container_ptr
236    }}
237}
238
239/// Helper for [`container_of!`].
240#[doc(hidden)]
241pub fn assert_same_type<T>(_: T, _: T) {}
242
243/// Helper for `.rs.S` files.
244#[doc(hidden)]
245#[macro_export]
246macro_rules! concat_literals {
247    ($( $asm:literal )* ) => {
248        ::core::concat!($($asm),*)
249    };
250}
251
252/// Wrapper around `asm!` configured for use in the kernel.
253///
254/// Uses a semicolon to avoid parsing ambiguities, even though this does not match native `asm!`
255/// syntax.
256// For x86, `asm!` uses intel syntax by default, but we want to use at&t syntax in the kernel.
257#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
258#[macro_export]
259macro_rules! asm {
260    ($($asm:expr),* ; $($rest:tt)*) => {
261        ::core::arch::asm!( $($asm)*, options(att_syntax), $($rest)* )
262    };
263}
264
265/// Wrapper around `asm!` configured for use in the kernel.
266///
267/// Uses a semicolon to avoid parsing ambiguities, even though this does not match native `asm!`
268/// syntax.
269// For non-x86 arches we just pass through to `asm!`.
270#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
271#[macro_export]
272macro_rules! asm {
273    ($($asm:expr),* ; $($rest:tt)*) => {
274        ::core::arch::asm!( $($asm)*, $($rest)* )
275    };
276}
kernel/lib.rs

kernel/
lib.rs
