rust: add `macros` crate
This crate contains all the procedural macros ("proc macros")
shared by all the kernel.
Procedural macros allow to create syntax extensions. They run at
compile-time and can consume as well as produce Rust syntax.
For instance, the `module!` macro that is used by Rust modules
is implemented here. It allows to easily declare the equivalent
information to the `MODULE_*` macros in C modules, e.g.:
module! {
type: RustMinimal,
name: b"rust_minimal",
author: b"Rust for Linux Contributors",
description: b"Rust minimal sample",
license: b"GPL",
}
Co-developed-by: Alex Gaynor <alex.gaynor@gmail.com>
Signed-off-by: Alex Gaynor <alex.gaynor@gmail.com>
Co-developed-by: Finn Behrens <me@kloenk.de>
Signed-off-by: Finn Behrens <me@kloenk.de>
Co-developed-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Signed-off-by: Adam Bratschi-Kaye <ark.email@gmail.com>
Co-developed-by: Wedson Almeida Filho <wedsonaf@google.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@google.com>
Co-developed-by: Sumera Priyadarsini <sylphrenadin@gmail.com>
Signed-off-by: Sumera Priyadarsini <sylphrenadin@gmail.com>
Co-developed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Gary Guo <gary@garyguo.net>
Co-developed-by: Matthew Bakhtiari <dev@mtbk.me>
Signed-off-by: Matthew Bakhtiari <dev@mtbk.me>
Co-developed-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Signed-off-by: Björn Roy Baron <bjorn3_gh@protonmail.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Miguel Ojeda
parent
db958dcf88
commit
1fbde52bde
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@ -0,0 +1,51 @@
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// SPDX-License-Identifier: GPL-2.0
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use proc_macro::{token_stream, TokenTree};
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pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> {
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if let Some(TokenTree::Ident(ident)) = it.next() {
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Some(ident.to_string())
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} else {
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None
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}
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}
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pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> {
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if let Some(TokenTree::Literal(literal)) = it.next() {
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Some(literal.to_string())
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} else {
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None
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}
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}
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pub(crate) fn try_byte_string(it: &mut token_stream::IntoIter) -> Option<String> {
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try_literal(it).and_then(|byte_string| {
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if byte_string.starts_with("b\"") && byte_string.ends_with('\"') {
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Some(byte_string[2..byte_string.len() - 1].to_string())
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} else {
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None
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}
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})
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}
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pub(crate) fn expect_ident(it: &mut token_stream::IntoIter) -> String {
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try_ident(it).expect("Expected Ident")
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}
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pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char {
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if let TokenTree::Punct(punct) = it.next().expect("Reached end of token stream for Punct") {
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punct.as_char()
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} else {
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panic!("Expected Punct");
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}
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}
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pub(crate) fn expect_byte_string(it: &mut token_stream::IntoIter) -> String {
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try_byte_string(it).expect("Expected byte string")
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}
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pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
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if it.next().is_some() {
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panic!("Expected end");
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}
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}
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@ -0,0 +1,72 @@
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// SPDX-License-Identifier: GPL-2.0
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//! Crate for all kernel procedural macros.
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mod helpers;
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mod module;
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use proc_macro::TokenStream;
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/// Declares a kernel module.
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///
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/// The `type` argument should be a type which implements the [`Module`]
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/// trait. Also accepts various forms of kernel metadata.
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///
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/// C header: [`include/linux/moduleparam.h`](../../../include/linux/moduleparam.h)
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///
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/// [`Module`]: ../kernel/trait.Module.html
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///
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/// # Examples
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///
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/// ```ignore
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/// use kernel::prelude::*;
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///
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/// module!{
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/// type: MyModule,
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/// name: b"my_kernel_module",
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/// author: b"Rust for Linux Contributors",
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/// description: b"My very own kernel module!",
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/// license: b"GPL",
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/// params: {
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/// my_i32: i32 {
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/// default: 42,
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/// permissions: 0o000,
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/// description: b"Example of i32",
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/// },
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/// writeable_i32: i32 {
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/// default: 42,
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/// permissions: 0o644,
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/// description: b"Example of i32",
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/// },
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/// },
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/// }
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///
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/// struct MyModule;
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///
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/// impl kernel::Module for MyModule {
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/// fn init() -> Result<Self> {
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/// // If the parameter is writeable, then the kparam lock must be
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/// // taken to read the parameter:
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/// {
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/// let lock = THIS_MODULE.kernel_param_lock();
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/// pr_info!("i32 param is: {}\n", writeable_i32.read(&lock));
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/// }
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/// // If the parameter is read only, it can be read without locking
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/// // the kernel parameters:
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/// pr_info!("i32 param is: {}\n", my_i32.read());
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/// Ok(Self)
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/// }
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/// }
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/// ```
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///
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/// # Supported argument types
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/// - `type`: type which implements the [`Module`] trait (required).
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/// - `name`: byte array of the name of the kernel module (required).
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/// - `author`: byte array of the author of the kernel module.
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/// - `description`: byte array of the description of the kernel module.
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/// - `license`: byte array of the license of the kernel module (required).
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/// - `alias`: byte array of alias name of the kernel module.
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#[proc_macro]
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pub fn module(ts: TokenStream) -> TokenStream {
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module::module(ts)
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}
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@ -0,0 +1,282 @@
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// SPDX-License-Identifier: GPL-2.0
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use crate::helpers::*;
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use proc_macro::{token_stream, Literal, TokenStream, TokenTree};
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use std::fmt::Write;
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struct ModInfoBuilder<'a> {
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module: &'a str,
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counter: usize,
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buffer: String,
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}
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impl<'a> ModInfoBuilder<'a> {
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fn new(module: &'a str) -> Self {
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ModInfoBuilder {
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module,
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counter: 0,
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buffer: String::new(),
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}
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}
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fn emit_base(&mut self, field: &str, content: &str, builtin: bool) {
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let string = if builtin {
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// Built-in modules prefix their modinfo strings by `module.`.
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format!(
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"{module}.{field}={content}\0",
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module = self.module,
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field = field,
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content = content
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)
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} else {
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// Loadable modules' modinfo strings go as-is.
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format!("{field}={content}\0", field = field, content = content)
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};
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write!(
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&mut self.buffer,
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"
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{cfg}
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#[doc(hidden)]
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#[link_section = \".modinfo\"]
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#[used]
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pub static __{module}_{counter}: [u8; {length}] = *{string};
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",
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cfg = if builtin {
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"#[cfg(not(MODULE))]"
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} else {
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"#[cfg(MODULE)]"
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},
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module = self.module.to_uppercase(),
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counter = self.counter,
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length = string.len(),
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string = Literal::byte_string(string.as_bytes()),
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)
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.unwrap();
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self.counter += 1;
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}
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fn emit_only_builtin(&mut self, field: &str, content: &str) {
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self.emit_base(field, content, true)
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}
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fn emit_only_loadable(&mut self, field: &str, content: &str) {
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self.emit_base(field, content, false)
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}
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fn emit(&mut self, field: &str, content: &str) {
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self.emit_only_builtin(field, content);
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self.emit_only_loadable(field, content);
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}
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}
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#[derive(Debug, Default)]
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struct ModuleInfo {
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type_: String,
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license: String,
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name: String,
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author: Option<String>,
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description: Option<String>,
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alias: Option<String>,
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}
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impl ModuleInfo {
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fn parse(it: &mut token_stream::IntoIter) -> Self {
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let mut info = ModuleInfo::default();
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const EXPECTED_KEYS: &[&str] =
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&["type", "name", "author", "description", "license", "alias"];
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const REQUIRED_KEYS: &[&str] = &["type", "name", "license"];
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let mut seen_keys = Vec::new();
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loop {
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let key = match it.next() {
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Some(TokenTree::Ident(ident)) => ident.to_string(),
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Some(_) => panic!("Expected Ident or end"),
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None => break,
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};
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if seen_keys.contains(&key) {
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panic!(
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"Duplicated key \"{}\". Keys can only be specified once.",
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key
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);
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}
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assert_eq!(expect_punct(it), ':');
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match key.as_str() {
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"type" => info.type_ = expect_ident(it),
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"name" => info.name = expect_byte_string(it),
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"author" => info.author = Some(expect_byte_string(it)),
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"description" => info.description = Some(expect_byte_string(it)),
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"license" => info.license = expect_byte_string(it),
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"alias" => info.alias = Some(expect_byte_string(it)),
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_ => panic!(
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"Unknown key \"{}\". Valid keys are: {:?}.",
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key, EXPECTED_KEYS
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),
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}
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assert_eq!(expect_punct(it), ',');
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seen_keys.push(key);
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}
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expect_end(it);
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for key in REQUIRED_KEYS {
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if !seen_keys.iter().any(|e| e == key) {
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panic!("Missing required key \"{}\".", key);
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}
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}
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let mut ordered_keys: Vec<&str> = Vec::new();
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for key in EXPECTED_KEYS {
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if seen_keys.iter().any(|e| e == key) {
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ordered_keys.push(key);
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}
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}
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if seen_keys != ordered_keys {
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panic!(
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"Keys are not ordered as expected. Order them like: {:?}.",
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ordered_keys
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);
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}
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info
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}
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}
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pub(crate) fn module(ts: TokenStream) -> TokenStream {
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let mut it = ts.into_iter();
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let info = ModuleInfo::parse(&mut it);
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let mut modinfo = ModInfoBuilder::new(info.name.as_ref());
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if let Some(author) = info.author {
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modinfo.emit("author", &author);
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}
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if let Some(description) = info.description {
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modinfo.emit("description", &description);
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}
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modinfo.emit("license", &info.license);
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if let Some(alias) = info.alias {
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modinfo.emit("alias", &alias);
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}
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// Built-in modules also export the `file` modinfo string.
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let file =
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std::env::var("RUST_MODFILE").expect("Unable to fetch RUST_MODFILE environmental variable");
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modinfo.emit_only_builtin("file", &file);
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format!(
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"
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/// The module name.
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///
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/// Used by the printing macros, e.g. [`info!`].
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const __LOG_PREFIX: &[u8] = b\"{name}\\0\";
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/// The \"Rust loadable module\" mark, for `scripts/is_rust_module.sh`.
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//
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// This may be best done another way later on, e.g. as a new modinfo
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// key or a new section. For the moment, keep it simple.
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#[cfg(MODULE)]
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#[doc(hidden)]
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#[used]
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static __IS_RUST_MODULE: () = ();
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static mut __MOD: Option<{type_}> = None;
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// SAFETY: `__this_module` is constructed by the kernel at load time and will not be
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// freed until the module is unloaded.
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#[cfg(MODULE)]
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static THIS_MODULE: kernel::ThisModule = unsafe {{
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kernel::ThisModule::from_ptr(&kernel::bindings::__this_module as *const _ as *mut _)
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}};
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#[cfg(not(MODULE))]
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static THIS_MODULE: kernel::ThisModule = unsafe {{
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kernel::ThisModule::from_ptr(core::ptr::null_mut())
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}};
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// Loadable modules need to export the `{{init,cleanup}}_module` identifiers.
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#[cfg(MODULE)]
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#[doc(hidden)]
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#[no_mangle]
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pub extern \"C\" fn init_module() -> core::ffi::c_int {{
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__init()
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}}
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#[cfg(MODULE)]
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#[doc(hidden)]
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#[no_mangle]
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pub extern \"C\" fn cleanup_module() {{
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__exit()
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}}
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// Built-in modules are initialized through an initcall pointer
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// and the identifiers need to be unique.
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#[cfg(not(MODULE))]
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#[cfg(not(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS))]
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#[doc(hidden)]
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#[link_section = \"{initcall_section}\"]
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#[used]
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pub static __{name}_initcall: extern \"C\" fn() -> core::ffi::c_int = __{name}_init;
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#[cfg(not(MODULE))]
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#[cfg(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)]
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core::arch::global_asm!(
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r#\".section \"{initcall_section}\", \"a\"
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__{name}_initcall:
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.long __{name}_init - .
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.previous
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\"#
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);
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#[cfg(not(MODULE))]
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#[doc(hidden)]
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#[no_mangle]
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pub extern \"C\" fn __{name}_init() -> core::ffi::c_int {{
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__init()
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}}
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#[cfg(not(MODULE))]
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#[doc(hidden)]
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#[no_mangle]
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pub extern \"C\" fn __{name}_exit() {{
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__exit()
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}}
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fn __init() -> core::ffi::c_int {{
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match <{type_} as kernel::Module>::init(&THIS_MODULE) {{
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Ok(m) => {{
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unsafe {{
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__MOD = Some(m);
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}}
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return 0;
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}}
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Err(e) => {{
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return e.to_kernel_errno();
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}}
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}}
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}}
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fn __exit() {{
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unsafe {{
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// Invokes `drop()` on `__MOD`, which should be used for cleanup.
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__MOD = None;
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}}
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}}
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{modinfo}
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",
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type_ = info.type_,
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name = info.name,
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modinfo = modinfo.buffer,
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initcall_section = ".initcall6.init"
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)
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.parse()
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.expect("Error parsing formatted string into token stream.")
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}
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