rust: add `build_error` crate

[linux-block.git] / rust / kernel / lib.rs

// SPDX-License-Identifier: GPL-2.0

//! The `kernel` crate.
//!
//! This crate contains the kernel APIs that have been ported or wrapped for
//! usage by Rust code in the kernel and is shared by all of them.
//!
//! In other words, all the rest of the Rust code in the kernel (e.g. kernel
//! modules written in Rust) depends on [`core`], [`alloc`] and this crate.
//!
//! If you need a kernel C API that is not ported or wrapped yet here, then
//! do so first instead of bypassing this crate.

#![no_std]
#![feature(allocator_api)]
#![feature(core_ffi_c)]

// Ensure conditional compilation based on the kernel configuration works;
// otherwise we may silently break things like initcall handling.
#[cfg(not(CONFIG_RUST))]
compile_error!("Missing kernel configuration for conditional compilation");

#[cfg(not(test))]
#[cfg(not(testlib))]
mod allocator;
pub mod error;
pub mod prelude;
pub mod print;
mod static_assert;
#[doc(hidden)]
pub mod std_vendor;
pub mod str;

#[doc(hidden)]
pub use bindings;
pub use macros;

/// Prefix to appear before log messages printed from within the `kernel` crate.
const __LOG_PREFIX: &[u8] = b"rust_kernel\0";

/// The top level entrypoint to implementing a kernel module.
///
/// For any teardown or cleanup operations, your type may implement [`Drop`].
pub trait Module: Sized + Sync {
    /// Called at module initialization time.
    ///
    /// Use this method to perform whatever setup or registration your module
    /// should do.
    ///
    /// Equivalent to the `module_init` macro in the C API.
    fn init(module: &'static ThisModule) -> error::Result<Self>;
}

/// Equivalent to `THIS_MODULE` in the C API.
///
/// C header: `include/linux/export.h`
pub struct ThisModule(*mut bindings::module);

// SAFETY: `THIS_MODULE` may be used from all threads within a module.
unsafe impl Sync for ThisModule {}

impl ThisModule {
    /// Creates a [`ThisModule`] given the `THIS_MODULE` pointer.
    ///
    /// # Safety
    ///
    /// The pointer must be equal to the right `THIS_MODULE`.
    pub const unsafe fn from_ptr(ptr: *mut bindings::module) -> ThisModule {
        ThisModule(ptr)
    }
}

#[cfg(not(any(testlib, test)))]
#[panic_handler]
fn panic(info: &core::panic::PanicInfo<'_>) -> ! {
    pr_emerg!("{}\n", info);
    // SAFETY: FFI call.
    unsafe { bindings::BUG() };
    // Bindgen currently does not recognize `__noreturn` so `BUG` returns `()`
    // instead of `!`. See <https://github.com/rust-lang/rust-bindgen/issues/2094>.
    loop {}
}