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`], [`alloc`] 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#![feature(arbitrary_self_types)]
 16#![feature(coerce_unsized)]
 17#![feature(dispatch_from_dyn)]
 18#![feature(inline_const)]
 19#![feature(lint_reasons)]
 20#![feature(unsize)]
 21
 22// Ensure conditional compilation based on the kernel configuration works;
 23// otherwise we may silently break things like initcall handling.
 24#[cfg(not(CONFIG_RUST))]
 25compile_error!("Missing kernel configuration for conditional compilation");
 26
 27// Allow proc-macros to refer to `::kernel` inside the `kernel` crate (this crate).
 28extern crate self as kernel;
 29
 30pub use ffi;
 31
 32pub mod alloc;
 33#[cfg(CONFIG_BLOCK)]
 34pub mod block;
 35mod build_assert;
 36pub mod cred;
 37pub mod device;
 38pub mod error;
 39#[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]
 40pub mod firmware;
 41pub mod fs;
 42pub mod init;
 43pub mod ioctl;
 44pub mod jump_label;
 45#[cfg(CONFIG_KUNIT)]
 46pub mod kunit;
 47pub mod list;
 48pub mod miscdevice;
 49#[cfg(CONFIG_NET)]
 50pub mod net;
 51pub mod page;
 52pub mod pid_namespace;
 53pub mod prelude;
 54pub mod print;
 55pub mod rbtree;
 56pub mod security;
 57pub mod seq_file;
 58pub mod sizes;
 59mod static_assert;
 60#[doc(hidden)]
 61pub mod std_vendor;
 62pub mod str;
 63pub mod sync;
 64pub mod task;
 65pub mod time;
 66pub mod tracepoint;
 67pub mod transmute;
 68pub mod types;
 69pub mod uaccess;
 70pub mod workqueue;
 71
 72#[doc(hidden)]
 73pub use bindings;
 74pub use macros;
 75pub use uapi;
 76
 77#[doc(hidden)]
 78pub use build_error::build_error;
 79
 80/// Prefix to appear before log messages printed from within the `kernel` crate.
 81const __LOG_PREFIX: &[u8] = b"rust_kernel\0";
 82
 83/// The top level entrypoint to implementing a kernel module.
 84///
 85/// For any teardown or cleanup operations, your type may implement [`Drop`].
 86pub trait Module: Sized + Sync + Send {
 87    /// Called at module initialization time.
 88    ///
 89    /// Use this method to perform whatever setup or registration your module
 90    /// should do.
 91    ///
 92    /// Equivalent to the `module_init` macro in the C API.
 93    fn init(module: &'static ThisModule) -> error::Result<Self>;
 94}
 95
 96/// A module that is pinned and initialised in-place.
 97pub trait InPlaceModule: Sync + Send {
 98    /// Creates an initialiser for the module.
 99    ///
100    /// It is called when the module is loaded.
101    fn init(module: &'static ThisModule) -> impl init::PinInit<Self, error::Error>;
102}
103
104impl<T: Module> InPlaceModule for T {
105    fn init(module: &'static ThisModule) -> impl init::PinInit<Self, error::Error> {
106        let initer = move |slot: *mut Self| {
107            let m = <Self as Module>::init(module)?;
108
109            // SAFETY: `slot` is valid for write per the contract with `pin_init_from_closure`.
110            unsafe { slot.write(m) };
111            Ok(())
112        };
113
114        // SAFETY: On success, `initer` always fully initialises an instance of `Self`.
115        unsafe { init::pin_init_from_closure(initer) }
116    }
117}
118
119/// Equivalent to `THIS_MODULE` in the C API.
120///
121/// C header: [`include/linux/init.h`](srctree/include/linux/init.h)
122pub struct ThisModule(*mut bindings::module);
123
124// SAFETY: `THIS_MODULE` may be used from all threads within a module.
125unsafe impl Sync for ThisModule {}
126
127impl ThisModule {
128    /// Creates a [`ThisModule`] given the `THIS_MODULE` pointer.
129    ///
130    /// # Safety
131    ///
132    /// The pointer must be equal to the right `THIS_MODULE`.
133    pub const unsafe fn from_ptr(ptr: *mut bindings::module) -> ThisModule {
134        ThisModule(ptr)
135    }
136
137    /// Access the raw pointer for this module.
138    ///
139    /// It is up to the user to use it correctly.
140    pub const fn as_ptr(&self) -> *mut bindings::module {
141        self.0
142    }
143}
144
145#[cfg(not(any(testlib, test)))]
146#[panic_handler]
147fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
148    pr_emerg!("{}\n", info);
149    // SAFETY: FFI call.
150    unsafe { bindings::BUG() };
151}
152
153/// Produces a pointer to an object from a pointer to one of its fields.
154///
155/// # Safety
156///
157/// The pointer passed to this macro, and the pointer returned by this macro, must both be in
158/// bounds of the same allocation.
159///
160/// # Examples
161///
162/// ```
163/// # use kernel::container_of;
164/// struct Test {
165///     a: u64,
166///     b: u32,
167/// }
168///
169/// let test = Test { a: 10, b: 20 };
170/// let b_ptr = &test.b;
171/// // SAFETY: The pointer points at the `b` field of a `Test`, so the resulting pointer will be
172/// // in-bounds of the same allocation as `b_ptr`.
173/// let test_alias = unsafe { container_of!(b_ptr, Test, b) };
174/// assert!(core::ptr::eq(&test, test_alias));
175/// ```
176#[macro_export]
177macro_rules! container_of {
178    ($ptr:expr, $type:ty, $($f:tt)*) => {{
179        let ptr = $ptr as *const _ as *const u8;
180        let offset: usize = ::core::mem::offset_of!($type, $($f)*);
181        ptr.sub(offset) as *const $type
182    }}
183}
184
185/// Helper for `.rs.S` files.
186#[doc(hidden)]
187#[macro_export]
188macro_rules! concat_literals {
189    ($( $asm:literal )* ) => {
190        ::core::concat!($($asm),*)
191    };
192}
193
194/// Wrapper around `asm!` configured for use in the kernel.
195///
196/// Uses a semicolon to avoid parsing ambiguities, even though this does not match native `asm!`
197/// syntax.
198// For x86, `asm!` uses intel syntax by default, but we want to use at&t syntax in the kernel.
199#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
200#[macro_export]
201macro_rules! asm {
202    ($($asm:expr),* ; $($rest:tt)*) => {
203        ::core::arch::asm!( $($asm)*, options(att_syntax), $($rest)* )
204    };
205}
206
207/// Wrapper around `asm!` configured for use in the kernel.
208///
209/// Uses a semicolon to avoid parsing ambiguities, even though this does not match native `asm!`
210/// syntax.
211// For non-x86 arches we just pass through to `asm!`.
212#[cfg(not(any(target_arch = "x86", target_arch = "x86_64")))]
213#[macro_export]
214macro_rules! asm {
215    ($($asm:expr),* ; $($rest:tt)*) => {
216        ::core::arch::asm!( $($asm)*, $($rest)* )
217    };
218}