[linux-block.git] / rust / macros / module.rs

// SPDX-License-Identifier: GPL-2.0

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

fn expect_string_array(it: &mut token_stream::IntoIter) -> Vec<String> {
    let group = expect_group(it);
    assert_eq!(group.delimiter(), Delimiter::Bracket);
    let mut values = Vec::new();
    let mut it = group.stream().into_iter();

    while let Some(val) = try_string(&mut it) {
        assert!(val.is_ascii(), "Expected ASCII string");
        values.push(val);
        match it.next() {
            Some(TokenTree::Punct(punct)) => assert_eq!(punct.as_char(), ','),
            None => break,
            _ => panic!("Expected ',' or end of array"),
        }
    }
    values
}

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<Vec<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_string_ascii(it),
                "author" => info.author = Some(expect_string(it)),
                "description" => info.description = Some(expect_string(it)),
                "license" => info.license = expect_string_ascii(it),
                "alias" => info.alias = Some(expect_string_array(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(aliases) = info.alias {
        for alias in aliases {
            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\";

            // 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())
            }};

            // Double nested modules, since then nobody can access the public items inside.
            mod __module_init {{
                mod __module_init {{
                    use super::super::{type_};

                    /// The \"Rust loadable module\" mark.
                    //
                    // 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;

                    // Loadable modules need to export the `{{init,cleanup}}_module` identifiers.
                    /// # Safety
                    ///
                    /// This function must not be called after module initialization, because it may be
                    /// freed after that completes.
                    #[cfg(MODULE)]
                    #[doc(hidden)]
                    #[no_mangle]
                    #[link_section = \".init.text\"]
                    pub unsafe extern \"C\" fn init_module() -> core::ffi::c_int {{
                        // SAFETY: This function is inaccessible to the outside due to the double
                        // module wrapping it. It is called exactly once by the C side via its
                        // unique name.
                        unsafe {{ __init() }}
                    }}

                    #[cfg(MODULE)]
                    #[doc(hidden)]
                    #[no_mangle]
                    pub extern \"C\" fn cleanup_module() {{
                        // SAFETY:
                        // - This function is inaccessible to the outside due to the double
                        //   module wrapping it. It is called exactly once by the C side via its
                        //   unique name,
                        // - furthermore it is only called after `init_module` has returned `0`
                        //   (which delegates to `__init`).
                        unsafe {{ __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 {{
                        // SAFETY: This function is inaccessible to the outside due to the double
                        // module wrapping it. It is called exactly once by the C side via its
                        // placement above in the initcall section.
                        unsafe {{ __init() }}
                    }}

                    #[cfg(not(MODULE))]
                    #[doc(hidden)]
                    #[no_mangle]
                    pub extern \"C\" fn __{name}_exit() {{
                        // SAFETY:
                        // - This function is inaccessible to the outside due to the double
                        //   module wrapping it. It is called exactly once by the C side via its
                        //   unique name,
                        // - furthermore it is only called after `__{name}_init` has returned `0`
                        //   (which delegates to `__init`).
                        unsafe {{ __exit() }}
                    }}

                    /// # Safety
                    ///
                    /// This function must only be called once.
                    unsafe fn __init() -> core::ffi::c_int {{
                        match <{type_} as kernel::Module>::init(&super::super::THIS_MODULE) {{
                            Ok(m) => {{
                                // SAFETY: No data race, since `__MOD` can only be accessed by this
                                // module and there only `__init` and `__exit` access it. These
                                // functions are only called once and `__exit` cannot be called
                                // before or during `__init`.
                                unsafe {{
                                    __MOD = Some(m);
                                }}
                                return 0;
                            }}
                            Err(e) => {{
                                return e.to_errno();
                            }}
                        }}
                    }}

                    /// # Safety
                    ///
                    /// This function must
                    /// - only be called once,
                    /// - be called after `__init` has been called and returned `0`.
                    unsafe fn __exit() {{
                        // SAFETY: No data race, since `__MOD` can only be accessed by this module
                        // and there only `__init` and `__exit` access it. These functions are only
                        // called once and `__init` was already called.
                        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.")
}
Commit	Line	Data
1fbde52b MO	1	// SPDX-License-Identifier: GPL-2.0
	2
	3	use crate::helpers::*;
39867fec	4	use proc_macro::{token_stream, Delimiter, Literal, TokenStream, TokenTree};
1fbde52b MO	5	use std::fmt::Write;
1fbde52b MO	6
39867fec AL	7	fn expect_string_array(it: &mut token_stream::IntoIter) -> Vec<String> {
	8	let group = expect_group(it);
	9	assert_eq!(group.delimiter(), Delimiter::Bracket);
	10	let mut values = Vec::new();
	11	let mut it = group.stream().into_iter();
	12
	13	while let Some(val) = try_string(&mut it) {
	14	assert!(val.is_ascii(), "Expected ASCII string");
	15	values.push(val);
	16	match it.next() {
	17	Some(TokenTree::Punct(punct)) => assert_eq!(punct.as_char(), ','),
	18	None => break,
	19	_ => panic!("Expected ',' or end of array"),
	20	}
	21	}
	22	values
	23	}
	24
1fbde52b MO	25	struct ModInfoBuilder<'a> {
	26	module: &'a str,
	27	counter: usize,
	28	buffer: String,
	29	}
	30
	31	impl<'a> ModInfoBuilder<'a> {
	32	fn new(module: &'a str) -> Self {
	33	ModInfoBuilder {
	34	module,
	35	counter: 0,
	36	buffer: String::new(),
	37	}
	38	}
	39
	40	fn emit_base(&mut self, field: &str, content: &str, builtin: bool) {
	41	let string = if builtin {
	42	// Built-in modules prefix their modinfo strings by `module.`.
	43	format!(
	44	"{module}.{field}={content}\0",
	45	module = self.module,
	46	field = field,
	47	content = content
	48	)
	49	} else {
	50	// Loadable modules' modinfo strings go as-is.
	51	format!("{field}={content}\0", field = field, content = content)
	52	};
	53
	54	write!(
	55	&mut self.buffer,
	56	"
	57	{cfg}
	58	#[doc(hidden)]
	59	#[link_section = \".modinfo\"]
	60	#[used]
	61	pub static __{module}_{counter}: [u8; {length}] = *{string};
	62	",
	63	cfg = if builtin {
	64	"#[cfg(not(MODULE))]"
	65	} else {
	66	"#[cfg(MODULE)]"
	67	},
	68	module = self.module.to_uppercase(),
	69	counter = self.counter,
	70	length = string.len(),
	71	string = Literal::byte_string(string.as_bytes()),
	72	)
	73	.unwrap();
	74
	75	self.counter += 1;
	76	}
	77
	78	fn emit_only_builtin(&mut self, field: &str, content: &str) {
	79	self.emit_base(field, content, true)
	80	}
	81
	82	fn emit_only_loadable(&mut self, field: &str, content: &str) {
	83	self.emit_base(field, content, false)
	84	}
	85
	86	fn emit(&mut self, field: &str, content: &str) {
	87	self.emit_only_builtin(field, content);
	88	self.emit_only_loadable(field, content);
89	}
90	}
91
92	#[derive(Debug, Default)]
93	struct ModuleInfo {
94	type_: String,
95	license: String,
96	name: String,
97	author: Option<String>,
98	description: Option<String>,
39867fec	99	alias: Option<Vec<String>>,
1fbde52b MO	100	}
	101
	102	impl ModuleInfo {
	103	fn parse(it: &mut token_stream::IntoIter) -> Self {
	104	let mut info = ModuleInfo::default();
	105
	106	const EXPECTED_KEYS: &[&str] =
	107	&["type", "name", "author", "description", "license", "alias"];
	108	const REQUIRED_KEYS: &[&str] = &["type", "name", "license"];
	109	let mut seen_keys = Vec::new();
	110
	111	loop {
	112	let key = match it.next() {
	113	Some(TokenTree::Ident(ident)) => ident.to_string(),
	114	Some(_) => panic!("Expected Ident or end"),
	115	None => break,
	116	};
	117
	118	if seen_keys.contains(&key) {
	119	panic!(
	120	"Duplicated key \"{}\". Keys can only be specified once.",
	121	key
	122	);
	123	}
	124
	125	assert_eq!(expect_punct(it), ':');
	126
	127	match key.as_str() {
	128	"type" => info.type_ = expect_ident(it),
b13c9880 GG	129	"name" => info.name = expect_string_ascii(it),
	130	"author" => info.author = Some(expect_string(it)),
	131	"description" => info.description = Some(expect_string(it)),
	132	"license" => info.license = expect_string_ascii(it),
39867fec	133	"alias" => info.alias = Some(expect_string_array(it)),
1fbde52b MO	134	_ => panic!(
	135	"Unknown key \"{}\". Valid keys are: {:?}.",
	136	key, EXPECTED_KEYS
	137	),
	138	}
	139
	140	assert_eq!(expect_punct(it), ',');
	141
	142	seen_keys.push(key);
	143	}
	144
	145	expect_end(it);
	146
	147	for key in REQUIRED_KEYS {
	148	if !seen_keys.iter().any(\|e\| e == key) {
	149	panic!("Missing required key \"{}\".", key);
	150	}
	151	}
	152
	153	let mut ordered_keys: Vec<&str> = Vec::new();
	154	for key in EXPECTED_KEYS {
	155	if seen_keys.iter().any(\|e\| e == key) {
	156	ordered_keys.push(key);
	157	}
	158	}
	159
	160	if seen_keys != ordered_keys {
	161	panic!(
	162	"Keys are not ordered as expected. Order them like: {:?}.",
	163	ordered_keys
	164	);
	165	}
	166
	167	info
	168	}
	169	}
	170
	171	pub(crate) fn module(ts: TokenStream) -> TokenStream {
	172	let mut it = ts.into_iter();
	173
	174	let info = ModuleInfo::parse(&mut it);
	175
	176	let mut modinfo = ModInfoBuilder::new(info.name.as_ref());
	177	if let Some(author) = info.author {
	178	modinfo.emit("author", &author);
	179	}
	180	if let Some(description) = info.description {
	181	modinfo.emit("description", &description);
	182	}
	183	modinfo.emit("license", &info.license);
39867fec AL	184	if let Some(aliases) = info.alias {
	185	for alias in aliases {
	186	modinfo.emit("alias", &alias);
	187	}
1fbde52b MO	188	}
	189
	190	// Built-in modules also export the `file` modinfo string.
	191	let file =
	192	std::env::var("RUST_MODFILE").expect("Unable to fetch RUST_MODFILE environmental variable");
	193	modinfo.emit_only_builtin("file", &file);
	194
	195	format!(
	196	"
	197	/// The module name.
	198	///
	199	/// Used by the printing macros, e.g. [`info!`].
	200	const __LOG_PREFIX: &[u8] = b\"{name}\\0\";
	201
1fbde52b MO	202	// SAFETY: `__this_module` is constructed by the kernel at load time and will not be
	203	// freed until the module is unloaded.
	204	#[cfg(MODULE)]
	205	static THIS_MODULE: kernel::ThisModule = unsafe {{
	206	kernel::ThisModule::from_ptr(&kernel::bindings::__this_module as const _ as mut _)
	207	}};
	208	#[cfg(not(MODULE))]
	209	static THIS_MODULE: kernel::ThisModule = unsafe {{
	210	kernel::ThisModule::from_ptr(core::ptr::null_mut())
	211	}};
	212
7044dcff BL	213	// Double nested modules, since then nobody can access the public items inside.
	214	mod __module_init {{
	215	mod __module_init {{
	216	use super::super::{type_};
	217
	218	/// The \"Rust loadable module\" mark.
	219	//
	220	// This may be best done another way later on, e.g. as a new modinfo
	221	// key or a new section. For the moment, keep it simple.
	222	#[cfg(MODULE)]
	223	#[doc(hidden)]
	224	#[used]
	225	static __IS_RUST_MODULE: () = ();
	226
	227	static mut __MOD: Option<{type_}> = None;
	228
	229	// Loadable modules need to export the `{{init,cleanup}}_module` identifiers.
	230	/// # Safety
	231	///
	232	/// This function must not be called after module initialization, because it may be
	233	/// freed after that completes.
	234	#[cfg(MODULE)]
	235	#[doc(hidden)]
	236	#[no_mangle]
	237	#[link_section = \".init.text\"]
	238	pub unsafe extern \"C\" fn init_module() -> core::ffi::c_int {{
	239	// SAFETY: This function is inaccessible to the outside due to the double
	240	// module wrapping it. It is called exactly once by the C side via its
	241	// unique name.
	242	unsafe {{ __init() }}
	243	}}
1fbde52b	244
7044dcff BL	245	#[cfg(MODULE)]
	246	#[doc(hidden)]
	247	#[no_mangle]
	248	pub extern \"C\" fn cleanup_module() {{
	249	// SAFETY:
	250	// - This function is inaccessible to the outside due to the double
	251	// module wrapping it. It is called exactly once by the C side via its
	252	// unique name,
	253	// - furthermore it is only called after `init_module` has returned `0`
	254	// (which delegates to `__init`).
	255	unsafe {{ __exit() }}
	256	}}
1fbde52b	257
7044dcff BL	258	// Built-in modules are initialized through an initcall pointer
	259	// and the identifiers need to be unique.
	260	#[cfg(not(MODULE))]
	261	#[cfg(not(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS))]
	262	#[doc(hidden)]
	263	#[link_section = \"{initcall_section}\"]
	264	#[used]
	265	pub static __{name}_initcall: extern \"C\" fn() -> core::ffi::c_int = __{name}_init;
	266
	267	#[cfg(not(MODULE))]
	268	#[cfg(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)]
	269	core::arch::global_asm!(
	270	r#\".section \"{initcall_section}\", \"a\"
	271	__{name}_initcall:
	272	.long __{name}_init - .
	273	.previous
	274	\"#
	275	);
	276
	277	#[cfg(not(MODULE))]
	278	#[doc(hidden)]
	279	#[no_mangle]
	280	pub extern \"C\" fn __{name}_init() -> core::ffi::c_int {{
	281	// SAFETY: This function is inaccessible to the outside due to the double
	282	// module wrapping it. It is called exactly once by the C side via its
	283	// placement above in the initcall section.
	284	unsafe {{ __init() }}
	285	}}
1fbde52b	286
7044dcff BL	287	#[cfg(not(MODULE))]
	288	#[doc(hidden)]
	289	#[no_mangle]
	290	pub extern \"C\" fn __{name}_exit() {{
	291	// SAFETY:
	292	// - This function is inaccessible to the outside due to the double
	293	// module wrapping it. It is called exactly once by the C side via its
	294	// unique name,
	295	// - furthermore it is only called after `__{name}_init` has returned `0`
	296	// (which delegates to `__init`).
	297	unsafe {{ __exit() }}
	298	}}
1fbde52b	299
7044dcff BL	300	/// # Safety
	301	///
	302	/// This function must only be called once.
	303	unsafe fn __init() -> core::ffi::c_int {{
	304	match <{type_} as kernel::Module>::init(&super::super::THIS_MODULE) {{
	305	Ok(m) => {{
	306	// SAFETY: No data race, since `__MOD` can only be accessed by this
	307	// module and there only `__init` and `__exit` access it. These
	308	// functions are only called once and `__exit` cannot be called
	309	// before or during `__init`.
	310	unsafe {{
	311	__MOD = Some(m);
	312	}}
	313	return 0;
	314	}}
	315	Err(e) => {{
	316	return e.to_errno();
	317	}}
	318	}}
	319	}}
1fbde52b	320
7044dcff BL	321	/// # Safety
	322	///
	323	/// This function must
	324	/// - only be called once,
	325	/// - be called after `__init` has been called and returned `0`.
	326	unsafe fn __exit() {{
	327	// SAFETY: No data race, since `__MOD` can only be accessed by this module
	328	// and there only `__init` and `__exit` access it. These functions are only
	329	// called once and `__init` was already called.
1fbde52b	330	unsafe {{
7044dcff BL	331	// Invokes `drop()` on `__MOD`, which should be used for cleanup.
7044dcff BL	332	__MOD = None;
1fbde52b	333	}}
1fbde52b	334	}}
1fbde52b	335
7044dcff	336	{modinfo}
1fbde52b MO	337	}}
1fbde52b MO	338	}}
1fbde52b MO	339	",
	340	type_ = info.type_,
	341	name = info.name,
	342	modinfo = modinfo.buffer,
	343	initcall_section = ".initcall6.init"
	344	)
	345	.parse()
	346	.expect("Error parsing formatted string into token stream.")
	347	}