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1 | Copyright 2010 Nicolas Palix <npalix@diku.dk> |
2 | Copyright 2010 Julia Lawall <julia@diku.dk> | |
3 | Copyright 2010 Gilles Muller <Gilles.Muller@lip6.fr> | |
4 | ||
5 | ||
6 | Getting Coccinelle | |
7 | ~~~~~~~~~~~~~~~~~~~~ | |
8 | ||
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9 | The semantic patches included in the kernel use features and options |
10 | which are provided by Coccinelle version 1.0.0-rc11 and above. | |
11 | Using earlier versions will fail as the option names used by | |
12 | the Coccinelle files and coccicheck have been updated. | |
e228b1e6 | 13 | |
ec97946e | 14 | Coccinelle is available through the package manager |
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15 | of many distributions, e.g. : |
16 | ||
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17 | - Debian |
18 | - Fedora | |
19 | - Ubuntu | |
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20 | - OpenSUSE |
21 | - Arch Linux | |
22 | - NetBSD | |
23 | - FreeBSD | |
24 | ||
25 | ||
26 | You can get the latest version released from the Coccinelle homepage at | |
27 | http://coccinelle.lip6.fr/ | |
28 | ||
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29 | Information and tips about Coccinelle are also provided on the wiki |
30 | pages at http://cocci.ekstranet.diku.dk/wiki/doku.php | |
31 | ||
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32 | Once you have it, run the following command: |
33 | ||
34 | ./configure | |
35 | make | |
36 | ||
37 | as a regular user, and install it with | |
38 | ||
39 | sudo make install | |
40 | ||
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41 | Using Coccinelle on the Linux kernel |
42 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
43 | ||
44 | A Coccinelle-specific target is defined in the top level | |
45 | Makefile. This target is named 'coccicheck' and calls the 'coccicheck' | |
46 | front-end in the 'scripts' directory. | |
47 | ||
78a95b9b | 48 | Four basic modes are defined: patch, report, context, and org. The mode to |
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49 | use is specified by setting the MODE variable with 'MODE=<mode>'. |
50 | ||
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51 | 'patch' proposes a fix, when possible. |
52 | ||
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53 | 'report' generates a list in the following format: |
54 | file:line:column-column: message | |
55 | ||
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56 | 'context' highlights lines of interest and their context in a |
57 | diff-like style.Lines of interest are indicated with '-'. | |
58 | ||
59 | 'org' generates a report in the Org mode format of Emacs. | |
60 | ||
32af0898 | 61 | Note that not all semantic patches implement all modes. For easy use |
78a95b9b | 62 | of Coccinelle, the default mode is "report". |
e228b1e6 | 63 | |
78a95b9b | 64 | Two other modes provide some common combinations of these modes. |
e228b1e6 | 65 | |
78a95b9b | 66 | 'chain' tries the previous modes in the order above until one succeeds. |
e228b1e6 | 67 | |
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68 | 'rep+ctxt' runs successively the report mode and the context mode. |
69 | It should be used with the C option (described later) | |
70 | which checks the code on a file basis. | |
e228b1e6 | 71 | |
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72 | Examples: |
73 | To make a report for every semantic patch, run the following command: | |
e228b1e6 | 74 | |
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75 | make coccicheck MODE=report |
76 | ||
77 | To produce patches, run: | |
78 | ||
79 | make coccicheck MODE=patch | |
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80 | |
81 | ||
82 | The coccicheck target applies every semantic patch available in the | |
32af0898 | 83 | sub-directories of 'scripts/coccinelle' to the entire Linux kernel. |
e228b1e6 | 84 | |
32af0898 | 85 | For each semantic patch, a commit message is proposed. It gives a |
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86 | description of the problem being checked by the semantic patch, and |
87 | includes a reference to Coccinelle. | |
88 | ||
89 | As any static code analyzer, Coccinelle produces false | |
90 | positives. Thus, reports must be carefully checked, and patches | |
91 | reviewed. | |
92 | ||
26e56720 BS |
93 | To enable verbose messages set the V= variable, for example: |
94 | ||
95 | make coccicheck MODE=report V=1 | |
96 | ||
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97 | Coccinelle parallelization |
98 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
99 | ||
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100 | By default, coccicheck tries to run as parallel as possible. To change |
101 | the parallelism, set the J= variable. For example, to run across 4 CPUs: | |
102 | ||
103 | make coccicheck MODE=report J=4 | |
104 | ||
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105 | As of Coccinelle 1.0.2 Coccinelle uses Ocaml parmap for parallelization, |
106 | if support for this is detected you will benefit from parmap parallelization. | |
107 | ||
108 | When parmap is enabled coccicheck will enable dynamic load balancing by using | |
109 | '--chunksize 1' argument, this ensures we keep feeding threads with work | |
110 | one by one, so that we avoid the situation where most work gets done by only | |
111 | a few threads. With dynamic load balancing, if a thread finishes early we keep | |
112 | feeding it more work. | |
113 | ||
114 | When parmap is enabled, if an error occurs in Coccinelle, this error | |
115 | value is propagated back, the return value of the 'make coccicheck' | |
116 | captures this return value. | |
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117 | |
118 | Using Coccinelle with a single semantic patch | |
119 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
120 | ||
121 | The optional make variable COCCI can be used to check a single | |
122 | semantic patch. In that case, the variable must be initialized with | |
123 | the name of the semantic patch to apply. | |
124 | ||
125 | For instance: | |
126 | ||
127 | make coccicheck COCCI=<my_SP.cocci> MODE=patch | |
128 | or | |
129 | make coccicheck COCCI=<my_SP.cocci> MODE=report | |
130 | ||
131 | ||
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132 | Controlling Which Files are Processed by Coccinelle |
133 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
134 | By default the entire kernel source tree is checked. | |
135 | ||
136 | To apply Coccinelle to a specific directory, M= can be used. | |
137 | For example, to check drivers/net/wireless/ one may write: | |
32af0898 | 138 | |
f95ab209 | 139 | make coccicheck M=drivers/net/wireless/ |
ed621cc4 | 140 | |
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141 | To apply Coccinelle on a file basis, instead of a directory basis, the |
142 | following command may be used: | |
143 | ||
144 | make C=1 CHECK="scripts/coccicheck" | |
145 | ||
146 | To check only newly edited code, use the value 2 for the C flag, i.e. | |
147 | ||
148 | make C=2 CHECK="scripts/coccicheck" | |
149 | ||
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150 | In these modes, which works on a file basis, there is no information |
151 | about semantic patches displayed, and no commit message proposed. | |
152 | ||
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153 | This runs every semantic patch in scripts/coccinelle by default. The |
154 | COCCI variable may additionally be used to only apply a single | |
155 | semantic patch as shown in the previous section. | |
156 | ||
78a95b9b | 157 | The "report" mode is the default. You can select another one with the |
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158 | MODE variable explained above. |
159 | ||
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160 | Additional flags |
161 | ~~~~~~~~~~~~~~~~~~ | |
162 | ||
163 | Additional flags can be passed to spatch through the SPFLAGS | |
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164 | variable. This works as Coccinelle respects the last flags |
165 | given to it when options are in conflict. | |
ed621cc4 | 166 | |
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167 | make SPFLAGS=--use-glimpse coccicheck |
168 | make SPFLAGS=--use-idutils coccicheck | |
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169 | |
170 | See spatch --help to learn more about spatch options. | |
32af0898 | 171 | |
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172 | Note that the '--use-glimpse' and '--use-idutils' options |
173 | require external tools for indexing the code. None of them is | |
174 | thus active by default. However, by indexing the code with | |
175 | one of these tools, and according to the cocci file used, | |
176 | spatch could proceed the entire code base more quickly. | |
177 | ||
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178 | Proposing new semantic patches |
179 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
180 | ||
181 | New semantic patches can be proposed and submitted by kernel | |
182 | developers. For sake of clarity, they should be organized in the | |
32af0898 | 183 | sub-directories of 'scripts/coccinelle/'. |
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184 | |
185 | ||
186 | Detailed description of the 'report' mode | |
187 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
188 | ||
189 | 'report' generates a list in the following format: | |
190 | file:line:column-column: message | |
191 | ||
192 | Example: | |
193 | ||
194 | Running | |
195 | ||
9dcf7990 | 196 | make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci |
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197 | |
198 | will execute the following part of the SmPL script. | |
199 | ||
200 | <smpl> | |
201 | @r depends on !context && !patch && (org || report)@ | |
202 | expression x; | |
203 | position p; | |
204 | @@ | |
205 | ||
206 | ERR_PTR@p(PTR_ERR(x)) | |
207 | ||
208 | @script:python depends on report@ | |
209 | p << r.p; | |
210 | x << r.x; | |
211 | @@ | |
212 | ||
213 | msg="ERR_CAST can be used with %s" % (x) | |
214 | coccilib.report.print_report(p[0], msg) | |
215 | </smpl> | |
216 | ||
217 | This SmPL excerpt generates entries on the standard output, as | |
218 | illustrated below: | |
219 | ||
220 | /home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg | |
221 | /home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth | |
222 | /home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg | |
223 | ||
224 | ||
225 | Detailed description of the 'patch' mode | |
226 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
227 | ||
228 | When the 'patch' mode is available, it proposes a fix for each problem | |
229 | identified. | |
230 | ||
231 | Example: | |
232 | ||
233 | Running | |
9dcf7990 | 234 | make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci |
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235 | |
236 | will execute the following part of the SmPL script. | |
237 | ||
238 | <smpl> | |
239 | @ depends on !context && patch && !org && !report @ | |
240 | expression x; | |
241 | @@ | |
242 | ||
243 | - ERR_PTR(PTR_ERR(x)) | |
244 | + ERR_CAST(x) | |
245 | </smpl> | |
246 | ||
247 | This SmPL excerpt generates patch hunks on the standard output, as | |
248 | illustrated below: | |
249 | ||
250 | diff -u -p a/crypto/ctr.c b/crypto/ctr.c | |
251 | --- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200 | |
252 | +++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200 | |
253 | @@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct | |
254 | alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, | |
255 | CRYPTO_ALG_TYPE_MASK); | |
256 | if (IS_ERR(alg)) | |
257 | - return ERR_PTR(PTR_ERR(alg)); | |
258 | + return ERR_CAST(alg); | |
259 | ||
260 | /* Block size must be >= 4 bytes. */ | |
261 | err = -EINVAL; | |
262 | ||
263 | Detailed description of the 'context' mode | |
264 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
265 | ||
266 | 'context' highlights lines of interest and their context | |
267 | in a diff-like style. | |
268 | ||
269 | NOTE: The diff-like output generated is NOT an applicable patch. The | |
270 | intent of the 'context' mode is to highlight the important lines | |
271 | (annotated with minus, '-') and gives some surrounding context | |
272 | lines around. This output can be used with the diff mode of | |
273 | Emacs to review the code. | |
274 | ||
275 | Example: | |
276 | ||
277 | Running | |
9dcf7990 | 278 | make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci |
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279 | |
280 | will execute the following part of the SmPL script. | |
281 | ||
282 | <smpl> | |
283 | @ depends on context && !patch && !org && !report@ | |
284 | expression x; | |
285 | @@ | |
286 | ||
287 | * ERR_PTR(PTR_ERR(x)) | |
288 | </smpl> | |
289 | ||
290 | This SmPL excerpt generates diff hunks on the standard output, as | |
291 | illustrated below: | |
292 | ||
293 | diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing | |
294 | --- /home/user/linux/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200 | |
295 | +++ /tmp/nothing | |
296 | @@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct | |
297 | alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, | |
298 | CRYPTO_ALG_TYPE_MASK); | |
299 | if (IS_ERR(alg)) | |
300 | - return ERR_PTR(PTR_ERR(alg)); | |
301 | ||
302 | /* Block size must be >= 4 bytes. */ | |
303 | err = -EINVAL; | |
304 | ||
305 | Detailed description of the 'org' mode | |
306 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
307 | ||
308 | 'org' generates a report in the Org mode format of Emacs. | |
309 | ||
310 | Example: | |
311 | ||
312 | Running | |
9dcf7990 | 313 | make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci |
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314 | |
315 | will execute the following part of the SmPL script. | |
316 | ||
317 | <smpl> | |
318 | @r depends on !context && !patch && (org || report)@ | |
319 | expression x; | |
320 | position p; | |
321 | @@ | |
322 | ||
323 | ERR_PTR@p(PTR_ERR(x)) | |
324 | ||
325 | @script:python depends on org@ | |
326 | p << r.p; | |
327 | x << r.x; | |
328 | @@ | |
329 | ||
330 | msg="ERR_CAST can be used with %s" % (x) | |
331 | msg_safe=msg.replace("[","@(").replace("]",")") | |
332 | coccilib.org.print_todo(p[0], msg_safe) | |
333 | </smpl> | |
334 | ||
335 | This SmPL excerpt generates Org entries on the standard output, as | |
336 | illustrated below: | |
337 | ||
338 | * TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]] | |
339 | * TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]] | |
340 | * TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]] |