macros/
module.rs

1// SPDX-License-Identifier: GPL-2.0
2
3use crate::helpers::*;
4use proc_macro::{token_stream, Delimiter, Literal, TokenStream, TokenTree};
5use std::fmt::Write;
6
7fn 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
25struct ModInfoBuilder<'a> {
26    module: &'a str,
27    counter: usize,
28    buffer: String,
29}
30
31impl<'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")
52        };
53
54        write!(
55            &mut self.buffer,
56            "
57                {cfg}
58                #[doc(hidden)]
59                #[cfg_attr(not(target_os = \"macos\"), 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)]
93struct ModuleInfo {
94    type_: String,
95    license: String,
96    name: String,
97    authors: Option<Vec<String>>,
98    description: Option<String>,
99    alias: Option<Vec<String>>,
100    firmware: Option<Vec<String>>,
101}
102
103impl ModuleInfo {
104    fn parse(it: &mut token_stream::IntoIter) -> Self {
105        let mut info = ModuleInfo::default();
106
107        const EXPECTED_KEYS: &[&str] = &[
108            "type",
109            "name",
110            "authors",
111            "description",
112            "license",
113            "alias",
114            "firmware",
115        ];
116        const REQUIRED_KEYS: &[&str] = &["type", "name", "license"];
117        let mut seen_keys = Vec::new();
118
119        loop {
120            let key = match it.next() {
121                Some(TokenTree::Ident(ident)) => ident.to_string(),
122                Some(_) => panic!("Expected Ident or end"),
123                None => break,
124            };
125
126            if seen_keys.contains(&key) {
127                panic!("Duplicated key \"{key}\". Keys can only be specified once.");
128            }
129
130            assert_eq!(expect_punct(it), ':');
131
132            match key.as_str() {
133                "type" => info.type_ = expect_ident(it),
134                "name" => info.name = expect_string_ascii(it),
135                "authors" => info.authors = Some(expect_string_array(it)),
136                "description" => info.description = Some(expect_string(it)),
137                "license" => info.license = expect_string_ascii(it),
138                "alias" => info.alias = Some(expect_string_array(it)),
139                "firmware" => info.firmware = Some(expect_string_array(it)),
140                _ => panic!("Unknown key \"{key}\". Valid keys are: {EXPECTED_KEYS:?}."),
141            }
142
143            assert_eq!(expect_punct(it), ',');
144
145            seen_keys.push(key);
146        }
147
148        expect_end(it);
149
150        for key in REQUIRED_KEYS {
151            if !seen_keys.iter().any(|e| e == key) {
152                panic!("Missing required key \"{key}\".");
153            }
154        }
155
156        let mut ordered_keys: Vec<&str> = Vec::new();
157        for key in EXPECTED_KEYS {
158            if seen_keys.iter().any(|e| e == key) {
159                ordered_keys.push(key);
160            }
161        }
162
163        if seen_keys != ordered_keys {
164            panic!("Keys are not ordered as expected. Order them like: {ordered_keys:?}.");
165        }
166
167        info
168    }
169}
170
171pub(crate) fn module(ts: TokenStream) -> TokenStream {
172    let mut it = ts.into_iter();
173
174    let info = ModuleInfo::parse(&mut it);
175
176    // Rust does not allow hyphens in identifiers, use underscore instead.
177    let ident = info.name.replace('-', "_");
178    let mut modinfo = ModInfoBuilder::new(ident.as_ref());
179    if let Some(authors) = info.authors {
180        for author in authors {
181            modinfo.emit("author", &author);
182        }
183    }
184    if let Some(description) = info.description {
185        modinfo.emit("description", &description);
186    }
187    modinfo.emit("license", &info.license);
188    if let Some(aliases) = info.alias {
189        for alias in aliases {
190            modinfo.emit("alias", &alias);
191        }
192    }
193    if let Some(firmware) = info.firmware {
194        for fw in firmware {
195            modinfo.emit("firmware", &fw);
196        }
197    }
198
199    // Built-in modules also export the `file` modinfo string.
200    let file =
201        std::env::var("RUST_MODFILE").expect("Unable to fetch RUST_MODFILE environmental variable");
202    modinfo.emit_only_builtin("file", &file);
203
204    format!(
205        "
206            /// The module name.
207            ///
208            /// Used by the printing macros, e.g. [`info!`].
209            const __LOG_PREFIX: &[u8] = b\"{name}\\0\";
210
211            // SAFETY: `__this_module` is constructed by the kernel at load time and will not be
212            // freed until the module is unloaded.
213            #[cfg(MODULE)]
214            static THIS_MODULE: ::kernel::ThisModule = unsafe {{
215                extern \"C\" {{
216                    static __this_module: ::kernel::types::Opaque<::kernel::bindings::module>;
217                }}
218
219                ::kernel::ThisModule::from_ptr(__this_module.get())
220            }};
221            #[cfg(not(MODULE))]
222            static THIS_MODULE: ::kernel::ThisModule = unsafe {{
223                ::kernel::ThisModule::from_ptr(::core::ptr::null_mut())
224            }};
225
226            /// The `LocalModule` type is the type of the module created by `module!`,
227            /// `module_pci_driver!`, `module_platform_driver!`, etc.
228            type LocalModule = {type_};
229
230            impl ::kernel::ModuleMetadata for {type_} {{
231                const NAME: &'static ::kernel::str::CStr = ::kernel::c_str!(\"{name}\");
232            }}
233
234            // Double nested modules, since then nobody can access the public items inside.
235            mod __module_init {{
236                mod __module_init {{
237                    use super::super::{type_};
238                    use pin_init::PinInit;
239
240                    /// The \"Rust loadable module\" mark.
241                    //
242                    // This may be best done another way later on, e.g. as a new modinfo
243                    // key or a new section. For the moment, keep it simple.
244                    #[cfg(MODULE)]
245                    #[doc(hidden)]
246                    #[used]
247                    static __IS_RUST_MODULE: () = ();
248
249                    static mut __MOD: ::core::mem::MaybeUninit<{type_}> =
250                        ::core::mem::MaybeUninit::uninit();
251
252                    // Loadable modules need to export the `{{init,cleanup}}_module` identifiers.
253                    /// # Safety
254                    ///
255                    /// This function must not be called after module initialization, because it may be
256                    /// freed after that completes.
257                    #[cfg(MODULE)]
258                    #[doc(hidden)]
259                    #[no_mangle]
260                    #[link_section = \".init.text\"]
261                    pub unsafe extern \"C\" fn init_module() -> ::kernel::ffi::c_int {{
262                        // SAFETY: This function is inaccessible to the outside due to the double
263                        // module wrapping it. It is called exactly once by the C side via its
264                        // unique name.
265                        unsafe {{ __init() }}
266                    }}
267
268                    #[cfg(MODULE)]
269                    #[doc(hidden)]
270                    #[used]
271                    #[link_section = \".init.data\"]
272                    static __UNIQUE_ID___addressable_init_module: unsafe extern \"C\" fn() -> i32 = init_module;
273
274                    #[cfg(MODULE)]
275                    #[doc(hidden)]
276                    #[no_mangle]
277                    #[link_section = \".exit.text\"]
278                    pub extern \"C\" fn cleanup_module() {{
279                        // SAFETY:
280                        // - This function is inaccessible to the outside due to the double
281                        //   module wrapping it. It is called exactly once by the C side via its
282                        //   unique name,
283                        // - furthermore it is only called after `init_module` has returned `0`
284                        //   (which delegates to `__init`).
285                        unsafe {{ __exit() }}
286                    }}
287
288                    #[cfg(MODULE)]
289                    #[doc(hidden)]
290                    #[used]
291                    #[link_section = \".exit.data\"]
292                    static __UNIQUE_ID___addressable_cleanup_module: extern \"C\" fn() = cleanup_module;
293
294                    // Built-in modules are initialized through an initcall pointer
295                    // and the identifiers need to be unique.
296                    #[cfg(not(MODULE))]
297                    #[cfg(not(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS))]
298                    #[doc(hidden)]
299                    #[link_section = \"{initcall_section}\"]
300                    #[used]
301                    pub static __{ident}_initcall: extern \"C\" fn() ->
302                        ::kernel::ffi::c_int = __{ident}_init;
303
304                    #[cfg(not(MODULE))]
305                    #[cfg(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)]
306                    ::core::arch::global_asm!(
307                        r#\".section \"{initcall_section}\", \"a\"
308                        __{ident}_initcall:
309                            .long   __{ident}_init - .
310                            .previous
311                        \"#
312                    );
313
314                    #[cfg(not(MODULE))]
315                    #[doc(hidden)]
316                    #[no_mangle]
317                    pub extern \"C\" fn __{ident}_init() -> ::kernel::ffi::c_int {{
318                        // SAFETY: This function is inaccessible to the outside due to the double
319                        // module wrapping it. It is called exactly once by the C side via its
320                        // placement above in the initcall section.
321                        unsafe {{ __init() }}
322                    }}
323
324                    #[cfg(not(MODULE))]
325                    #[doc(hidden)]
326                    #[no_mangle]
327                    pub extern \"C\" fn __{ident}_exit() {{
328                        // SAFETY:
329                        // - This function is inaccessible to the outside due to the double
330                        //   module wrapping it. It is called exactly once by the C side via its
331                        //   unique name,
332                        // - furthermore it is only called after `__{ident}_init` has
333                        //   returned `0` (which delegates to `__init`).
334                        unsafe {{ __exit() }}
335                    }}
336
337                    /// # Safety
338                    ///
339                    /// This function must only be called once.
340                    unsafe fn __init() -> ::kernel::ffi::c_int {{
341                        let initer =
342                            <{type_} as ::kernel::InPlaceModule>::init(&super::super::THIS_MODULE);
343                        // SAFETY: No data race, since `__MOD` can only be accessed by this module
344                        // and there only `__init` and `__exit` access it. These functions are only
345                        // called once and `__exit` cannot be called before or during `__init`.
346                        match unsafe {{ initer.__pinned_init(__MOD.as_mut_ptr()) }} {{
347                            Ok(m) => 0,
348                            Err(e) => e.to_errno(),
349                        }}
350                    }}
351
352                    /// # Safety
353                    ///
354                    /// This function must
355                    /// - only be called once,
356                    /// - be called after `__init` has been called and returned `0`.
357                    unsafe fn __exit() {{
358                        // SAFETY: No data race, since `__MOD` can only be accessed by this module
359                        // and there only `__init` and `__exit` access it. These functions are only
360                        // called once and `__init` was already called.
361                        unsafe {{
362                            // Invokes `drop()` on `__MOD`, which should be used for cleanup.
363                            __MOD.assume_init_drop();
364                        }}
365                    }}
366
367                    {modinfo}
368                }}
369            }}
370        ",
371        type_ = info.type_,
372        name = info.name,
373        ident = ident,
374        modinfo = modinfo.buffer,
375        initcall_section = ".initcall6.init"
376    )
377    .parse()
378    .expect("Error parsing formatted string into token stream.")
379}