rust: add `macros` crate (1fbde52b) · Commits · jan.koester / Linux

rust/macros/helpers.rs

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		// SPDX-License-Identifier: GPL-2.0

		use proc_macro::{token_stream, TokenTree};

		pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> {
		if let Some(TokenTree::Ident(ident)) = it.next() {
		Some(ident.to_string())
		} else {
		None
		}
		}

		pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> {
		if let Some(TokenTree::Literal(literal)) = it.next() {
		Some(literal.to_string())
		} else {
		None
		}
		}

		pub(crate) fn try_byte_string(it: &mut token_stream::IntoIter) -> Option<String> {
		try_literal(it).and_then(\|byte_string\| {
		if byte_string.starts_with("b\"") && byte_string.ends_with('\"') {
		Some(byte_string[2..byte_string.len() - 1].to_string())
		} else {
		None
		}
		})
		}

		pub(crate) fn expect_ident(it: &mut token_stream::IntoIter) -> String {
		try_ident(it).expect("Expected Ident")
		}

		pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char {
		if let TokenTree::Punct(punct) = it.next().expect("Reached end of token stream for Punct") {
		punct.as_char()
		} else {
		panic!("Expected Punct");
		}
		}

		pub(crate) fn expect_byte_string(it: &mut token_stream::IntoIter) -> String {
		try_byte_string(it).expect("Expected byte string")
		}

		pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
		if it.next().is_some() {
		panic!("Expected end");
		}
		}

rust/macros/lib.rs

0 → 100644

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		// SPDX-License-Identifier: GPL-2.0

		//! Crate for all kernel procedural macros.

		mod helpers;
		mod module;

		use proc_macro::TokenStream;

		/// Declares a kernel module.
		///
		/// The `type` argument should be a type which implements the [`Module`]
		/// trait. Also accepts various forms of kernel metadata.
		///
		/// C header: [`include/linux/moduleparam.h`](../../../include/linux/moduleparam.h)
		///
		/// [`Module`]: ../kernel/trait.Module.html
		///
		/// # Examples
		///
		/// ```ignore
		/// use kernel::prelude::*;
		///
		/// module!{
		/// type: MyModule,
		/// name: b"my_kernel_module",
		/// author: b"Rust for Linux Contributors",
		/// description: b"My very own kernel module!",
		/// license: b"GPL",
		/// params: {
		/// my_i32: i32 {
		/// default: 42,
		/// permissions: 0o000,
		/// description: b"Example of i32",
		/// },
		/// writeable_i32: i32 {
		/// default: 42,
		/// permissions: 0o644,
		/// description: b"Example of i32",
		/// },
		/// },
		/// }
		///
		/// struct MyModule;
		///
		/// impl kernel::Module for MyModule {
		/// fn init() -> Result<Self> {
		/// // If the parameter is writeable, then the kparam lock must be
		/// // taken to read the parameter:
		/// {
		/// let lock = THIS_MODULE.kernel_param_lock();
		/// pr_info!("i32 param is: {}\n", writeable_i32.read(&lock));
		/// }
		/// // If the parameter is read only, it can be read without locking
		/// // the kernel parameters:
		/// pr_info!("i32 param is: {}\n", my_i32.read());
		/// Ok(Self)
		/// }
		/// }
		/// ```
		///
		/// # Supported argument types
		/// - `type`: type which implements the [`Module`] trait (required).
		/// - `name`: byte array of the name of the kernel module (required).
		/// - `author`: byte array of the author of the kernel module.
		/// - `description`: byte array of the description of the kernel module.
		/// - `license`: byte array of the license of the kernel module (required).
		/// - `alias`: byte array of alias name of the kernel module.
		#[proc_macro]
		pub fn module(ts: TokenStream) -> TokenStream {
		module::module(ts)
		}

rust/macros/module.rs

0 → 100644

+282 −0

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		// SPDX-License-Identifier: GPL-2.0

		use crate::helpers::*;
		use proc_macro::{token_stream, Literal, TokenStream, TokenTree};
		use std::fmt::Write;

		struct ModInfoBuilder<'a> {
		module: &'a str,
		counter: usize,
		buffer: String,
		}

		impl<'a> ModInfoBuilder<'a> {
		fn new(module: &'a str) -> Self {
		ModInfoBuilder {
		module,
		counter: 0,
		buffer: String::new(),
		}
		}

		fn emit_base(&mut self, field: &str, content: &str, builtin: bool) {
		let string = if builtin {
		// Built-in modules prefix their modinfo strings by `module.`.
		format!(
		"{module}.{field}={content}\0",
		module = self.module,
		field = field,
		content = content
		)
		} else {
		// Loadable modules' modinfo strings go as-is.
		format!("{field}={content}\0", field = field, content = content)
		};

		write!(
		&mut self.buffer,
		"
		{cfg}
		#[doc(hidden)]
		#[link_section = \".modinfo\"]
		#[used]
		pub static __{module}_{counter}: [u8; {length}] = *{string};
		",
		cfg = if builtin {
		"#[cfg(not(MODULE))]"
		} else {
		"#[cfg(MODULE)]"
		},
		module = self.module.to_uppercase(),
		counter = self.counter,
		length = string.len(),
		string = Literal::byte_string(string.as_bytes()),
		)
		.unwrap();

		self.counter += 1;
		}

		fn emit_only_builtin(&mut self, field: &str, content: &str) {
		self.emit_base(field, content, true)
		}

		fn emit_only_loadable(&mut self, field: &str, content: &str) {
		self.emit_base(field, content, false)
		}

		fn emit(&mut self, field: &str, content: &str) {
		self.emit_only_builtin(field, content);
		self.emit_only_loadable(field, content);
		}
		}

		#[derive(Debug, Default)]
		struct ModuleInfo {
		type_: String,
		license: String,
		name: String,
		author: Option<String>,
		description: Option<String>,
		alias: Option<String>,
		}

		impl ModuleInfo {
		fn parse(it: &mut token_stream::IntoIter) -> Self {
		let mut info = ModuleInfo::default();

		const EXPECTED_KEYS: &[&str] =
		&["type", "name", "author", "description", "license", "alias"];
		const REQUIRED_KEYS: &[&str] = &["type", "name", "license"];
		let mut seen_keys = Vec::new();

		loop {
		let key = match it.next() {
		Some(TokenTree::Ident(ident)) => ident.to_string(),
		Some(_) => panic!("Expected Ident or end"),
		None => break,
		};

		if seen_keys.contains(&key) {
		panic!(
		"Duplicated key \"{}\". Keys can only be specified once.",
		key
		);
		}

		assert_eq!(expect_punct(it), ':');

		match key.as_str() {
		"type" => info.type_ = expect_ident(it),
		"name" => info.name = expect_byte_string(it),
		"author" => info.author = Some(expect_byte_string(it)),
		"description" => info.description = Some(expect_byte_string(it)),
		"license" => info.license = expect_byte_string(it),
		"alias" => info.alias = Some(expect_byte_string(it)),
		_ => panic!(
		"Unknown key \"{}\". Valid keys are: {:?}.",
		key, EXPECTED_KEYS
		),
		}

		assert_eq!(expect_punct(it), ',');

		seen_keys.push(key);
		}

		expect_end(it);

		for key in REQUIRED_KEYS {
		if !seen_keys.iter().any(\|e\| e == key) {
		panic!("Missing required key \"{}\".", key);
		}
		}

		let mut ordered_keys: Vec<&str> = Vec::new();
		for key in EXPECTED_KEYS {
		if seen_keys.iter().any(\|e\| e == key) {
		ordered_keys.push(key);
		}
		}

		if seen_keys != ordered_keys {
		panic!(
		"Keys are not ordered as expected. Order them like: {:?}.",
		ordered_keys
		);
		}

		info
		}
		}

		pub(crate) fn module(ts: TokenStream) -> TokenStream {
		let mut it = ts.into_iter();

		let info = ModuleInfo::parse(&mut it);

		let mut modinfo = ModInfoBuilder::new(info.name.as_ref());
		if let Some(author) = info.author {
		modinfo.emit("author", &author);
		}
		if let Some(description) = info.description {
		modinfo.emit("description", &description);
		}
		modinfo.emit("license", &info.license);
		if let Some(alias) = info.alias {
		modinfo.emit("alias", &alias);
		}

		// Built-in modules also export the `file` modinfo string.
		let file =
		std::env::var("RUST_MODFILE").expect("Unable to fetch RUST_MODFILE environmental variable");
		modinfo.emit_only_builtin("file", &file);

		format!(
		"
		/// The module name.
		///
		/// Used by the printing macros, e.g. [`info!`].
		const __LOG_PREFIX: &[u8] = b\"{name}\\0\";

		/// The \"Rust loadable module\" mark, for `scripts/is_rust_module.sh`.
		//
		// This may be best done another way later on, e.g. as a new modinfo
		// key or a new section. For the moment, keep it simple.
		#[cfg(MODULE)]
		#[doc(hidden)]
		#[used]
		static __IS_RUST_MODULE: () = ();

		static mut __MOD: Option<{type_}> = None;

		// SAFETY: `__this_module` is constructed by the kernel at load time and will not be
		// freed until the module is unloaded.
		#[cfg(MODULE)]
		static THIS_MODULE: kernel::ThisModule = unsafe {{
		kernel::ThisModule::from_ptr(&kernel::bindings::__this_module as const _ as mut _)
		}};
		#[cfg(not(MODULE))]
		static THIS_MODULE: kernel::ThisModule = unsafe {{
		kernel::ThisModule::from_ptr(core::ptr::null_mut())
		}};

		// Loadable modules need to export the `{{init,cleanup}}_module` identifiers.
		#[cfg(MODULE)]
		#[doc(hidden)]
		#[no_mangle]
		pub extern \"C\" fn init_module() -> core::ffi::c_int {{
		__init()
		}}

		#[cfg(MODULE)]
		#[doc(hidden)]
		#[no_mangle]
		pub extern \"C\" fn cleanup_module() {{
		__exit()
		}}

		// Built-in modules are initialized through an initcall pointer
		// and the identifiers need to be unique.
		#[cfg(not(MODULE))]
		#[cfg(not(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS))]
		#[doc(hidden)]
		#[link_section = \"{initcall_section}\"]
		#[used]
		pub static __{name}_initcall: extern \"C\" fn() -> core::ffi::c_int = __{name}_init;

		#[cfg(not(MODULE))]
		#[cfg(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)]
		core::arch::global_asm!(
		r#\".section \"{initcall_section}\", \"a\"
		__{name}_initcall:
		.long __{name}_init - .
		.previous
		\"#
		);

		#[cfg(not(MODULE))]
		#[doc(hidden)]
		#[no_mangle]
		pub extern \"C\" fn __{name}_init() -> core::ffi::c_int {{
		__init()
		}}

		#[cfg(not(MODULE))]
		#[doc(hidden)]
		#[no_mangle]
		pub extern \"C\" fn __{name}_exit() {{
		__exit()
		}}

		fn __init() -> core::ffi::c_int {{
		match <{type_} as kernel::Module>::init(&THIS_MODULE) {{
		Ok(m) => {{
		unsafe {{
		__MOD = Some(m);
		}}
		return 0;
		}}
		Err(e) => {{
		return e.to_kernel_errno();
		}}
		}}
		}}

		fn __exit() {{
		unsafe {{
		// Invokes `drop()` on `__MOD`, which should be used for cleanup.
		__MOD = None;
		}}
		}}

		{modinfo}
		",
		type_ = info.type_,
		name = info.name,
		modinfo = modinfo.buffer,
		initcall_section = ".initcall6.init"
		)
		.parse()
		.expect("Error parsing formatted string into token stream.")
		}