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>
9 The semantic patches included in the kernel use the 'virtual rule'
10 feature which was introduced in Coccinelle version 0.1.11.
12 Coccinelle (>=0.2.0) is available through the package manager
13 of many distributions, e.g. :
17 - Ubuntu (>=10.04 Lucid Lynx)
24 You can get the latest version released from the Coccinelle homepage at
25 http://coccinelle.lip6.fr/
27 Information and tips about Coccinelle are also provided on the wiki
28 pages at http://cocci.ekstranet.diku.dk/wiki/doku.php
30 Once you have it, run the following command:
35 as a regular user, and install it with
39 The semantic patches in the kernel will work best with Coccinelle version
40 0.2.4 or later. Using earlier versions may incur some parse errors in the
41 semantic patch code, but any results that are obtained should still be
44 Using Coccinelle on the Linux kernel
45 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
47 A Coccinelle-specific target is defined in the top level
48 Makefile. This target is named 'coccicheck' and calls the 'coccicheck'
49 front-end in the 'scripts' directory.
51 Four modes are defined: patch, report, context, and org. The mode to
52 use is specified by setting the MODE variable with 'MODE=<mode>'.
54 'patch' proposes a fix, when possible.
56 'report' generates a list in the following format:
57 file:line:column-column: message
59 'context' highlights lines of interest and their context in a
60 diff-like style.Lines of interest are indicated with '-'.
62 'org' generates a report in the Org mode format of Emacs.
64 Note that not all semantic patches implement all modes. For easy use
65 of Coccinelle, the default mode is "chain" which tries the previous
66 modes in the order above until one succeeds.
68 To make a report for every semantic patch, run the following command:
70 make coccicheck MODE=report
72 NB: The 'report' mode is the default one.
74 To produce patches, run:
76 make coccicheck MODE=patch
79 The coccicheck target applies every semantic patch available in the
80 sub-directories of 'scripts/coccinelle' to the entire Linux kernel.
82 For each semantic patch, a commit message is proposed. It gives a
83 description of the problem being checked by the semantic patch, and
84 includes a reference to Coccinelle.
86 As any static code analyzer, Coccinelle produces false
87 positives. Thus, reports must be carefully checked, and patches
91 Using Coccinelle with a single semantic patch
92 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
94 The optional make variable COCCI can be used to check a single
95 semantic patch. In that case, the variable must be initialized with
96 the name of the semantic patch to apply.
100 make coccicheck COCCI=<my_SP.cocci> MODE=patch
102 make coccicheck COCCI=<my_SP.cocci> MODE=report
105 Controlling Which Files are Processed by Coccinelle
106 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
107 By default the entire kernel source tree is checked.
109 To apply Coccinelle to a specific directory, M= can be used.
110 For example, to check drivers/net/wireless/ one may write:
112 make coccicheck M=drivers/net/wireless/
114 To apply Coccinelle on a file basis, instead of a directory basis, the
115 following command may be used:
117 make C=1 CHECK="scripts/coccicheck"
119 To check only newly edited code, use the value 2 for the C flag, i.e.
121 make C=2 CHECK="scripts/coccicheck"
123 This runs every semantic patch in scripts/coccinelle by default. The
124 COCCI variable may additionally be used to only apply a single
125 semantic patch as shown in the previous section.
127 The "chain" mode is the default. You can select another one with the
128 MODE variable explained above.
130 In this mode, there is no information about semantic patches
131 displayed, and no commit message proposed.
134 Proposing new semantic patches
135 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
137 New semantic patches can be proposed and submitted by kernel
138 developers. For sake of clarity, they should be organized in the
139 sub-directories of 'scripts/coccinelle/'.
142 Detailed description of the 'report' mode
143 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
145 'report' generates a list in the following format:
146 file:line:column-column: message
152 make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
154 will execute the following part of the SmPL script.
157 @r depends on !context && !patch && (org || report)@
162 ERR_PTR@p(PTR_ERR(x))
164 @script:python depends on report@
169 msg="ERR_CAST can be used with %s" % (x)
170 coccilib.report.print_report(p[0], msg)
173 This SmPL excerpt generates entries on the standard output, as
176 /home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
177 /home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
178 /home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg
181 Detailed description of the 'patch' mode
182 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
184 When the 'patch' mode is available, it proposes a fix for each problem
190 make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci
192 will execute the following part of the SmPL script.
195 @ depends on !context && patch && !org && !report @
199 - ERR_PTR(PTR_ERR(x))
203 This SmPL excerpt generates patch hunks on the standard output, as
206 diff -u -p a/crypto/ctr.c b/crypto/ctr.c
207 --- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
208 +++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
209 @@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
210 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
211 CRYPTO_ALG_TYPE_MASK);
213 - return ERR_PTR(PTR_ERR(alg));
214 + return ERR_CAST(alg);
216 /* Block size must be >= 4 bytes. */
219 Detailed description of the 'context' mode
220 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
222 'context' highlights lines of interest and their context
223 in a diff-like style.
225 NOTE: The diff-like output generated is NOT an applicable patch. The
226 intent of the 'context' mode is to highlight the important lines
227 (annotated with minus, '-') and gives some surrounding context
228 lines around. This output can be used with the diff mode of
229 Emacs to review the code.
234 make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
236 will execute the following part of the SmPL script.
239 @ depends on context && !patch && !org && !report@
243 * ERR_PTR(PTR_ERR(x))
246 This SmPL excerpt generates diff hunks on the standard output, as
249 diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
250 --- /home/user/linux/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
252 @@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
253 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
254 CRYPTO_ALG_TYPE_MASK);
256 - return ERR_PTR(PTR_ERR(alg));
258 /* Block size must be >= 4 bytes. */
261 Detailed description of the 'org' mode
262 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
264 'org' generates a report in the Org mode format of Emacs.
269 make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
271 will execute the following part of the SmPL script.
274 @r depends on !context && !patch && (org || report)@
279 ERR_PTR@p(PTR_ERR(x))
281 @script:python depends on org@
286 msg="ERR_CAST can be used with %s" % (x)
287 msg_safe=msg.replace("[","@(").replace("]",")")
288 coccilib.org.print_todo(p[0], msg_safe)
291 This SmPL excerpt generates Org entries on the standard output, as
294 * TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
295 * TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
296 * TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]