aboutsummaryrefslogtreecommitdiff
path: root/gnu/build/linux-modules.scm
blob: 3dd60f434f72f02221f6bac491059828786db552 (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
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2014, 2016, 2018 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu build linux-modules)
  #:use-module (guix elf)
  #:use-module (guix glob)
  #:use-module (guix build syscalls)
  #:use-module (rnrs io ports)
  #:use-module (rnrs bytevectors)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-26)
  #:use-module (ice-9 vlist)
  #:use-module (ice-9 match)
  #:use-module (ice-9 rdelim)
  #:export (dot-ko
            ensure-dot-ko
            module-aliases
            module-dependencies
            recursive-module-dependencies
            modules-loaded
            module-loaded?
            load-linux-module*

            current-module-debugging-port

            device-module-aliases
            known-module-aliases
            matching-modules))

;;; Commentary:
;;;
;;; Tools to deal with Linux kernel modules.
;;;
;;; Code:

(define current-module-debugging-port
  (make-parameter (%make-void-port "w")))

(define (section-contents elf section)
  "Return the contents of SECTION in ELF as a bytevector."
  (let* ((modinfo  (elf-section-by-name elf ".modinfo"))
         (contents (make-bytevector (elf-section-size modinfo))))
    (bytevector-copy! (elf-bytes elf) (elf-section-offset modinfo)
                      contents 0
                      (elf-section-size modinfo))
    contents))

(define %not-nul
  (char-set-complement (char-set #\nul)))

(define (nul-separated-string->list str)
  "Split STR at occurrences of the NUL character and return the resulting
string list."
  (string-tokenize str %not-nul))

(define (key=value->pair str)
  "Assuming STR has the form \"KEY=VALUE\", return a pair like (KEY
. \"VALUE\")."
  (let ((= (string-index str #\=)))
    (cons (string->symbol (string-take str =))
          (string-drop str (+ 1 =)))))

(define (modinfo-section-contents file)
  "Return the contents of the '.modinfo' section of FILE as a list of
key/value pairs.."
  (let* ((bv      (call-with-input-file file get-bytevector-all))
         (elf     (parse-elf bv))
         (modinfo (section-contents elf ".modinfo")))
    (map key=value->pair
         (nul-separated-string->list (utf8->string modinfo)))))

(define %not-comma
  (char-set-complement (char-set #\,)))

(define (module-dependencies file)
  "Return the list of modules that FILE depends on.  The returned list
contains module names, not actual file names."
  (let ((info (modinfo-section-contents file)))
    (match (assq 'depends info)
      (('depends . what)
       (string-tokenize what %not-comma)))))

(define (module-aliases file)
  "Return the list of aliases of module FILE."
  (let ((info (modinfo-section-contents file)))
    (filter-map (match-lambda
                 (('alias . value)
                  value)
                 (_ #f))
                (modinfo-section-contents file))))

(define dot-ko
  (cut string-append <> ".ko"))

(define (ensure-dot-ko name)
  "Return NAME with a '.ko' prefix appended, unless it already has it."
  (if (string-suffix? ".ko" name)
      name
      (dot-ko name)))

(define (normalize-module-name module)
  "Return the \"canonical\" name for MODULE, replacing hyphens with
underscores."
  ;; See 'modname_normalize' in libkmod.
  (string-map (lambda (chr)
                (case chr
                  ((#\-) #\_)
                  (else chr)))
              module))

(define (file-name->module-name file)
  "Return the module name corresponding to FILE, stripping the trailing '.ko'
and normalizing it."
  (normalize-module-name (basename file ".ko")))

(define* (recursive-module-dependencies files
                                        #:key (lookup-module dot-ko))
  "Return the topologically-sorted list of file names of the modules depended
on by FILES, recursively.  File names of modules are determined by applying
LOOKUP-MODULE to the module name."
  (let loop ((files   files)
             (result  '())
             (visited vlist-null))
    (match files
      (()
       (delete-duplicates (reverse result)))
      ((head . tail)
       (let* ((visited? (vhash-assoc head visited))
              (deps     (if visited?
                            '()
                            (map lookup-module (module-dependencies head))))
              (visited  (if visited?
                            visited
                            (vhash-cons head #t visited))))
         (loop (append deps tail)
               (append result deps) visited))))))

(define %not-newline
  (char-set-complement (char-set #\newline)))

(define (modules-loaded)
  "Return the list of names of currently loaded Linux modules."
  (let* ((contents (call-with-input-file "/proc/modules"
                     get-string-all))
         (lines    (string-tokenize contents %not-newline)))
    (match (map string-tokenize lines)
      (((modules . _) ...)
       modules))))

(define (module-black-list)
  "Return the black list of modules that must not be loaded.  This black list
is specified using 'modprobe.blacklist=MODULE1,MODULE2,...' on the kernel
command line; it is honored by libkmod for users that pass
'KMOD_PROBE_APPLY_BLACKLIST', which includes 'modprobe --use-blacklist' and
udev."
  (define parameter
    "modprobe.blacklist=")

  (let ((command (call-with-input-file "/proc/cmdline"
                   get-string-all)))
    (append-map (lambda (arg)
                  (if (string-prefix? parameter arg)
                      (string-tokenize (string-drop arg (string-length parameter))
                                       %not-comma)
                      '()))
                (string-tokenize command))))

(define (module-loaded? module)
  "Return #t if MODULE is already loaded.  MODULE must be a Linux module name,
not a file name."
  (member module (modules-loaded)))

(define* (load-linux-module* file
                             #:key
                             (recursive? #t)
                             (lookup-module dot-ko)
                             (black-list (module-black-list)))
  "Load Linux module from FILE, the name of a '.ko' file; return true on
success, false otherwise.  When RECURSIVE? is true, load its dependencies
first (à la 'modprobe'.)  The actual files containing modules depended on are
obtained by calling LOOKUP-MODULE with the module name.  Modules whose name
appears in BLACK-LIST are not loaded."
  (define (black-listed? module)
    (let ((result (member module black-list)))
      (when result
        (format (current-module-debugging-port)
                "not loading module '~a' because it's black-listed~%"
                module))
      result))

  (define (load-dependencies file)
    (let ((dependencies (module-dependencies file)))
      (every (cut load-linux-module* <> #:lookup-module lookup-module)
             (map lookup-module dependencies))))

  (and (not (black-listed? (file-name->module-name file)))
       (or (not recursive?)
           (load-dependencies file))
       (let ((fd #f))
         (format (current-module-debugging-port)
                 "loading Linux module from '~a'...~%" file)

         (catch 'system-error
           (lambda ()
             (set! fd (open-fdes file O_RDONLY))
             (load-linux-module/fd fd)
             (close-fdes fd)
             #t)
           (lambda args
             ;; If this module was already loaded and we're in modprobe style, ignore
             ;; the error.
             (when fd (close-fdes fd))
             (or (and recursive? (= EEXIST (system-error-errno args)))
                 (apply throw args)))))))


;;;
;;; Device modules.
;;;

;; Copied from (guix utils).  FIXME: Factorize.
(define (readlink* file)
  "Call 'readlink' until the result is not a symlink."
  (define %max-symlink-depth 50)

  (let loop ((file  file)
             (depth 0))
    (define (absolute target)
      (if (absolute-file-name? target)
          target
          (string-append (dirname file) "/" target)))

    (if (>= depth %max-symlink-depth)
        file
        (call-with-values
            (lambda ()
              (catch 'system-error
                (lambda ()
                  (values #t (readlink file)))
                (lambda args
                  (let ((errno (system-error-errno args)))
                    (if (or (= errno EINVAL))
                        (values #f file)
                        (apply throw args))))))
          (lambda (success? target)
            (if success?
                (loop (absolute target) (+ depth 1))
                file))))))

;; See 'major' and 'minor' in <sys/sysmacros.h>.

(define (stat->device-major st)
  (ash (logand #xfff00 (stat:rdev st)) -8))

(define (stat->device-minor st)
  (logand #xff (stat:rdev st)))

(define %not-slash
  (char-set-complement (char-set #\/)))

(define (read-uevent port)
  "Read a /sys 'uevent' file from PORT and return an alist where each car is a
key such as 'MAJOR or 'DEVTYPE and each cdr is the corresponding value."
  (let loop ((result '()))
    (match (read-line port)
      ((? eof-object?)
       (reverse result))
      (line
       (loop (cons (key=value->pair line) result))))))

(define (device-module-aliases device)
  "Return the list of module aliases required by DEVICE, a /dev file name, as
in this example:

  (device-module-aliases \"/dev/sda\")
  => (\"scsi:t-0x00\" \"pci:v00008086d00009D03sv0000103Csd000080FAbc01sc06i01\")

The modules corresponding to these aliases can then be found using
'matching-modules'."
  ;; The approach is adapted from
  ;; <https://unix.stackexchange.com/questions/97676/how-to-find-the-driver-module-associated-with-a-device-on-linux>.
  (let* ((st        (stat device))
         (type      (stat:type st))
         (major     (stat->device-major st))
         (minor     (stat->device-minor st))
         (sys-name  (string-append "/sys/dev/"
                                   (case type
                                     ((block-special) "block")
                                     ((char-special)  "char")
                                     (else (symbol->string type)))
                                   "/" (number->string major) ":"
                                   (number->string minor)))
         (directory (canonicalize-path (readlink* sys-name))))
    (let loop ((components (string-tokenize directory %not-slash))
               (aliases    '()))
      (match components
        (("sys" "devices" _)
         (reverse aliases))
        ((head ... _)
         (let ((uevent (string-append (string-join components "/" 'prefix)
                                      "/uevent")))
           (if (file-exists? uevent)
               (let ((props (call-with-input-file uevent read-uevent)))
                 (match (assq-ref props 'MODALIAS)
                   (#f    (loop head aliases))
                   (alias (loop head (cons alias aliases)))))
               (loop head aliases))))))))

(define (read-module-aliases port)
  "Read from PORT data in the Linux 'modules.alias' file format.  Return a
list of alias/module pairs where each alias is a glob pattern as like the
result of:

  (compile-glob-pattern \"scsi:t-0x01*\")

and each module is a module name like \"snd_hda_intel\"."
  (define (comment? str)
    (string-prefix? "#" str))

  (define (tokenize str)
    ;; Lines have the form "alias ALIAS MODULE", where ALIAS can contain
    ;; whitespace.  This is why we don't use 'string-tokenize'.
    (let* ((str   (string-trim-both str))
           (left  (string-index str #\space))
           (right (string-rindex str #\space)))
      (list (string-take str left)
            (string-trim-both (substring str left right))
            (string-trim-both (string-drop str right)))))

  (let loop ((aliases '()))
    (match (read-line port)
      ((? eof-object?)
       (reverse aliases))
      ((? comment?)
       (loop aliases))
      (line
       (match (tokenize line)
         (("alias" alias module)
          (loop (alist-cons (compile-glob-pattern alias) module
                            aliases)))
         (()                                      ;empty line
          (loop aliases)))))))

(define (current-kernel-directory)
  "Return the directory of the currently running Linux kernel."
  (string-append (or (getenv "LINUX_MODULE_DIRECTORY")
                     "/run/booted-system/kernel/lib/modules")
                 "/" (utsname:release (uname))))

(define (current-alias-file)
  "Return the absolute file name of the default 'modules.alias' file."
  (string-append (current-kernel-directory) "/modules.alias"))

(define* (known-module-aliases #:optional (alias-file (current-alias-file)))
  "Return the list of alias/module pairs read from ALIAS-FILE.  Each alias is
actually a pattern."
  (call-with-input-file alias-file read-module-aliases))

(define* (matching-modules alias
                           #:optional (known-aliases (known-module-aliases)))
  "Return the list of modules that match ALIAS according to KNOWN-ALIASES.
ALIAS is a string like \"scsi:t-0x00\" as returned by
'device-module-aliases'."
  (filter-map (match-lambda
                ((pattern . module)
                 (and (glob-match? pattern alias)
                      module)))
              known-aliases))

;;; linux-modules.scm ends here