summaryrefslogtreecommitdiffstats
path: root/rust/macros/module.rs
blob: 27979e582e4b943b963a88ee7cecdea4f345b83f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
// 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\";

            /// 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;

            // 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.
            /// # 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 {{
                __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_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.")
}