1 .. Copyright 2010 Nicolas Palix <npalix@diku.dk
2 .. Copyright 2010 Julia Lawall <julia@diku.dk>
3 .. Copyright 2010 Gilles Muller <Gilles.Muller@
4
5 .. highlight:: none
6
7 .. _devtools_coccinelle:
8
9 Coccinelle
10 ==========
11
12 Coccinelle is a tool for pattern matching and
13 many uses in kernel development, including the
14 tree-wide patches and detection of problematic
15
16 Getting Coccinelle
17 ------------------
18
19 The semantic patches included in the kernel us
20 which are provided by Coccinelle version 1.0.0
21 Using earlier versions will fail as the option
22 the Coccinelle files and coccicheck have been
23
24 Coccinelle is available through the package ma
25 of many distributions, e.g. :
26
27 - Debian
28 - Fedora
29 - Ubuntu
30 - OpenSUSE
31 - Arch Linux
32 - NetBSD
33 - FreeBSD
34
35 Some distribution packages are obsolete and it
36 to use the latest version released from the Co
37 http://coccinelle.lip6.fr/
38
39 Or from Github at:
40
41 https://github.com/coccinelle/coccinelle
42
43 Once you have it, run the following commands::
44
45 ./autogen
46 ./configure
47 make
48
49 as a regular user, and install it with::
50
51 sudo make install
52
53 More detailed installation instructions to bui
54 found at:
55
56 https://github.com/coccinelle/coccinelle/blob/
57
58 Supplemental documentation
59 --------------------------
60
61 For supplemental documentation refer to the wi
62
63 https://bottest.wiki.kernel.org/coccicheck
64
65 The wiki documentation always refers to the li
66
67 For Semantic Patch Language(SmPL) grammar docu
68
69 https://coccinelle.gitlabpages.inria.fr/websit
70
71 Using Coccinelle on the Linux kernel
72 ------------------------------------
73
74 A Coccinelle-specific target is defined in the
75 Makefile. This target is named ``coccicheck``
76 front-end in the ``scripts`` directory.
77
78 Four basic modes are defined: ``patch``, ``rep
79 ``org``. The mode to use is specified by setti
80 ``MODE=<mode>``.
81
82 - ``patch`` proposes a fix, when possible.
83
84 - ``report`` generates a list in the following
85 file:line:column-column: message
86
87 - ``context`` highlights lines of interest and
88 diff-like style. Lines of interest are indic
89
90 - ``org`` generates a report in the Org mode f
91
92 Note that not all semantic patches implement a
93 of Coccinelle, the default mode is "report".
94
95 Two other modes provide some common combinatio
96
97 - ``chain`` tries the previous modes in the or
98
99 - ``rep+ctxt`` runs successively the report mo
100 It should be used with the C option (describ
101 which checks the code on a file basis.
102
103 Examples
104 ~~~~~~~~
105
106 To make a report for every semantic patch, run
107
108 make coccicheck MODE=report
109
110 To produce patches, run::
111
112 make coccicheck MODE=patch
113
114
115 The coccicheck target applies every semantic p
116 sub-directories of ``scripts/coccinelle`` to t
117
118 For each semantic patch, a commit message is p
119 description of the problem being checked by th
120 includes a reference to Coccinelle.
121
122 As with any static code analyzer, Coccinelle p
123 positives. Thus, reports must be carefully che
124 reviewed.
125
126 To enable verbose messages set the V= variable
127
128 make coccicheck MODE=report V=1
129
130 Coccinelle parallelization
131 --------------------------
132
133 By default, coccicheck tries to run as paralle
134 the parallelism, set the J= variable. For exam
135
136 make coccicheck MODE=report J=4
137
138 As of Coccinelle 1.0.2 Coccinelle uses Ocaml p
139 if support for this is detected you will benef
140
141 When parmap is enabled coccicheck will enable
142 ``--chunksize 1`` argument. This ensures we ke
143 one by one, so that we avoid the situation whe
144 a few threads. With dynamic load balancing, if
145 feeding it more work.
146
147 When parmap is enabled, if an error occurs in
148 value is propagated back, and the return value
149 command captures this return value.
150
151 Using Coccinelle with a single semantic patch
152 ---------------------------------------------
153
154 The optional make variable COCCI can be used t
155 semantic patch. In that case, the variable mus
156 the name of the semantic patch to apply.
157
158 For instance::
159
160 make coccicheck COCCI=<my_SP.cocci> MO
161
162 or::
163
164 make coccicheck COCCI=<my_SP.cocci> MO
165
166
167 Controlling Which Files are Processed by Cocci
168 ----------------------------------------------
169
170 By default the entire kernel source tree is ch
171
172 To apply Coccinelle to a specific directory, `
173 For example, to check drivers/net/wireless/ on
174
175 make coccicheck M=drivers/net/wireless/
176
177 To apply Coccinelle on a file basis, instead o
178 C variable is used by the makefile to select w
179 This variable can be used to run scripts for t
180 specific directory, or for a single file.
181
182 For example, to check drivers/bluetooth/bfusb.
183 passed to the C variable to check files that m
184 need to be compiled.::
185
186 make C=1 CHECK=scripts/coccicheck drivers/
187
188 The value 2 is passed to the C variable to che
189 whether they need to be compiled or not.::
190
191 make C=2 CHECK=scripts/coccicheck drivers/
192
193 In these modes, which work on a file basis, th
194 about semantic patches displayed, and no commi
195
196 This runs every semantic patch in scripts/cocc
197 COCCI variable may additionally be used to onl
198 semantic patch as shown in the previous sectio
199
200 The "report" mode is the default. You can sele
201 MODE variable explained above.
202
203 Debugging Coccinelle SmPL patches
204 ---------------------------------
205
206 Using coccicheck is best as it provides in the
207 include options matching the options used when
208 You can learn what these options are by using
209 manually run Coccinelle with debug options add
210
211 Alternatively you can debug running Coccinelle
212 by asking for stderr to be redirected to stder
213 is redirected to /dev/null; if you'd like to c
214 can specify the ``DEBUG_FILE="file.txt"`` opti
215 instance::
216
217 rm -f cocci.err
218 make coccicheck COCCI=scripts/coccinelle/f
219 cat cocci.err
220
221 You can use SPFLAGS to add debugging flags; fo
222 add both ``--profile --show-trying`` to SPFLAG
223 you may want to use::
224
225 rm -f err.log
226 export COCCI=scripts/coccinelle/misc/irqf_
227 make coccicheck DEBUG_FILE="err.log" MODE=
228
229 err.log will now have the profiling informatio
230 provide some progress information as Coccinell
231 work.
232
233 NOTE:
234
235 DEBUG_FILE support is only supported when usin
236
237 Currently, DEBUG_FILE support is only availabl
238 not single files. This is because checking a s
239 to be called twice leading to DEBUG_FILE being
240 giving rise to an error.
241
242 .cocciconfig support
243 --------------------
244
245 Coccinelle supports reading .cocciconfig for d
246 should be used every time spatch is spawned. T
247 variables for .cocciconfig is as follows:
248
249 - Your current user's home directory is proces
250 - Your directory from which spatch is called i
251 - The directory provided with the ``--dir`` op
252
253 Since coccicheck runs through make, it natural
254 proper dir; as such the second rule above woul
255 .cocciconfig when using ``make coccicheck``.
256
257 ``make coccicheck`` also supports using M= tar
258 any M= target, it is assumed you want to targe
259 The kernel coccicheck script has::
260
261 if [ "$KBUILD_EXTMOD" = "" ] ; then
262 OPTIONS="--dir $srctree $COCCIINCLUDE"
263 else
264 OPTIONS="--dir $KBUILD_EXTMOD $COCCIIN
265 fi
266
267 KBUILD_EXTMOD is set when an explicit target w
268 the spatch ``--dir`` argument is used, as such
269 M= is used or not, and when M= is used the tar
270 .cocciconfig file. When M= is not passed as an
271 target directory is the same as the directory
272
273 If not using the kernel's coccicheck target, k
274 order logic of .cocciconfig reading. If using
275 override any of the kernel's .coccicheck's set
276
277 We help Coccinelle when used against Linux wit
278 options for Linux with our own Linux .coccicon
279 that git can be used for ``git grep`` queries
280 seconds should suffice for now.
281
282 The options picked up by coccinelle when readi
283 as arguments to spatch processes running on yo
284 options will be used by Coccinelle run::
285
286 spatch --print-options-only
287
288 You can override with your own preferred index
289 note that when there are conflicting options C
290 the last options passed. Using .cocciconfig is
291 given the order of precedence followed by Cocc
292 carries its own .cocciconfig, you will need to
293 desired. See below section "Additional flags"
294 idutils.
295
296 Additional flags
297 ----------------
298
299 Additional flags can be passed to spatch throu
300 variable. This works as Coccinelle respects th
301 given to it when options are in conflict. ::
302
303 make SPFLAGS=--use-glimpse coccicheck
304
305 Coccinelle supports idutils as well but requir
306 When no ID file is specified coccinelle assume
307 is in the file .id-utils.index on the top leve
308 carries a script scripts/idutils_index.sh whic
309
310 mkid -i C --output .id-utils.index
311
312 If you have another database filename you can
313 name. ::
314
315 make SPFLAGS=--use-idutils coccicheck
316
317 Alternatively you can specify the database fil
318 instance::
319
320 make SPFLAGS="--use-idutils /full-path/to/
321
322 See ``spatch --help`` to learn more about spat
323
324 Note that the ``--use-glimpse`` and ``--use-id
325 require external tools for indexing the code.
326 thus active by default. However, by indexing t
327 one of these tools, and according to the cocci
328 spatch could proceed the entire code base more
329
330 SmPL patch specific options
331 ---------------------------
332
333 SmPL patches can have their own requirements f
334 to Coccinelle. SmPL patch-specific options can
335 providing them at the top of the SmPL patch, f
336
337 // Options: --no-includes --include-he
338
339 SmPL patch Coccinelle requirements
340 ----------------------------------
341
342 As Coccinelle features get added some more adv
343 may require newer versions of Coccinelle. If a
344 a minimum version of Coccinelle, this can be s
345 as an example if requiring at least Coccinelle
346
347 // Requires: 1.0.5
348
349 Proposing new semantic patches
350 ------------------------------
351
352 New semantic patches can be proposed and submi
353 developers. For sake of clarity, they should b
354 sub-directories of ``scripts/coccinelle/``.
355
356
357 Detailed description of the ``report`` mode
358 -------------------------------------------
359
360 ``report`` generates a list in the following f
361
362 file:line:column-column: message
363
364 Example
365 ~~~~~~~
366
367 Running::
368
369 make coccicheck MODE=report COCCI=scri
370
371 will execute the following part of the SmPL sc
372
373 <smpl>
374 @r depends on !context && !patch && (org ||
375 expression x;
376 position p;
377 @@
378
379 ERR_PTR@p(PTR_ERR(x))
380
381 @script:python depends on report@
382 p << r.p;
383 x << r.x;
384 @@
385
386 msg="ERR_CAST can be used with %s" % (x)
387 coccilib.report.print_report(p[0], msg)
388 </smpl>
389
390 This SmPL excerpt generates entries on the sta
391 illustrated below::
392
393 /home/user/linux/crypto/ctr.c:188:9-16: ER
394 /home/user/linux/crypto/authenc.c:619:9-16
395 /home/user/linux/crypto/xts.c:227:9-16: ER
396
397
398 Detailed description of the ``patch`` mode
399 ------------------------------------------
400
401 When the ``patch`` mode is available, it propo
402 identified.
403
404 Example
405 ~~~~~~~
406
407 Running::
408
409 make coccicheck MODE=patch COCCI=scrip
410
411 will execute the following part of the SmPL sc
412
413 <smpl>
414 @ depends on !context && patch && !org &&
415 expression x;
416 @@
417
418 - ERR_PTR(PTR_ERR(x))
419 + ERR_CAST(x)
420 </smpl>
421
422 This SmPL excerpt generates patch hunks on the
423 illustrated below::
424
425 diff -u -p a/crypto/ctr.c b/crypto/ctr.c
426 --- a/crypto/ctr.c 2010-05-26 10:49:38.000
427 +++ b/crypto/ctr.c 2010-06-03 23:44:49.000
428 @@ -185,7 +185,7 @@ static struct crypto_i
429 alg = crypto_attr_alg(tb[1], CRYPTO_AL
430 CRYPTO_ALG_T
431 if (IS_ERR(alg))
432 - return ERR_PTR(PTR_ERR(alg));
433 + return ERR_CAST(alg);
434
435 /* Block size must be >= 4 bytes. */
436 err = -EINVAL;
437
438 Detailed description of the ``context`` mode
439 --------------------------------------------
440
441 ``context`` highlights lines of interest and t
442 in a diff-like style.
443
444 **NOTE**: The diff-like output generated
445 intent of the ``context`` mode is to hig
446 (annotated with minus, ``-``) and gives
447 lines around. This output can be used wi
448 Emacs to review the code.
449
450 Example
451 ~~~~~~~
452
453 Running::
454
455 make coccicheck MODE=context COCCI=scr
456
457 will execute the following part of the SmPL sc
458
459 <smpl>
460 @ depends on context && !patch && !org &&
461 expression x;
462 @@
463
464 * ERR_PTR(PTR_ERR(x))
465 </smpl>
466
467 This SmPL excerpt generates diff hunks on the
468 illustrated below::
469
470 diff -u -p /home/user/linux/crypto/ctr.c /
471 --- /home/user/linux/crypto/ctr.c 2010-0
472 +++ /tmp/nothing
473 @@ -185,7 +185,6 @@ static struct crypto_i
474 alg = crypto_attr_alg(tb[1], CRYPTO_AL
475 CRYPTO_ALG_T
476 if (IS_ERR(alg))
477 - return ERR_PTR(PTR_ERR(alg));
478
479 /* Block size must be >= 4 bytes. */
480 err = -EINVAL;
481
482 Detailed description of the ``org`` mode
483 ----------------------------------------
484
485 ``org`` generates a report in the Org mode for
486
487 Example
488 ~~~~~~~
489
490 Running::
491
492 make coccicheck MODE=org COCCI=scripts
493
494 will execute the following part of the SmPL sc
495
496 <smpl>
497 @r depends on !context && !patch && (org |
498 expression x;
499 position p;
500 @@
501
502 ERR_PTR@p(PTR_ERR(x))
503
504 @script:python depends on org@
505 p << r.p;
506 x << r.x;
507 @@
508
509 msg="ERR_CAST can be used with %s" % (x)
510 msg_safe=msg.replace("[","@(").replace("]"
511 coccilib.org.print_todo(p[0], msg_safe)
512 </smpl>
513
514 This SmPL excerpt generates Org entries on the
515 illustrated below::
516
517 * TODO [[view:/home/user/linux/crypto/ctr.
518 * TODO [[view:/home/user/linux/crypto/auth
519 * TODO [[view:/home/user/linux/crypto/xts.
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