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
90 To enable verbose messages set the V= variable, for example:
92 make coccicheck MODE=report V=1
94 By default, coccicheck tries to run as parallel as possible. To change
95 the parallelism, set the J= variable. For example, to run across 4 CPUs:
97 make coccicheck MODE=report J=4
100 Using Coccinelle with a single semantic patch
101 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
103 The optional make variable COCCI can be used to check a single
104 semantic patch. In that case, the variable must be initialized with
105 the name of the semantic patch to apply.
109 make coccicheck COCCI=<my_SP.cocci> MODE=patch
111 make coccicheck COCCI=<my_SP.cocci> MODE=report
114 Controlling Which Files are Processed by Coccinelle
115 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
116 By default the entire kernel source tree is checked.
118 To apply Coccinelle to a specific directory, M= can be used.
119 For example, to check drivers/net/wireless/ one may write:
121 make coccicheck M=drivers/net/wireless/
123 To apply Coccinelle on a file basis, instead of a directory basis, the
124 following command may be used:
126 make C=1 CHECK="scripts/coccicheck"
128 To check only newly edited code, use the value 2 for the C flag, i.e.
130 make C=2 CHECK="scripts/coccicheck"
132 This runs every semantic patch in scripts/coccinelle by default. The
133 COCCI variable may additionally be used to only apply a single
134 semantic patch as shown in the previous section.
136 The "chain" mode is the default. You can select another one with the
137 MODE variable explained above.
139 In this mode, there is no information about semantic patches
140 displayed, and no commit message proposed.
145 Additional flags can be passed to spatch through the SPFLAGS
148 make SPFLAGS=--use_glimpse coccicheck
150 See spatch --help to learn more about spatch options.
152 Proposing new semantic patches
153 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
155 New semantic patches can be proposed and submitted by kernel
156 developers. For sake of clarity, they should be organized in the
157 sub-directories of 'scripts/coccinelle/'.
160 Detailed description of the 'report' mode
161 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
163 'report' generates a list in the following format:
164 file:line:column-column: message
170 make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
172 will execute the following part of the SmPL script.
175 @r depends on !context && !patch && (org || report)@
180 ERR_PTR@p(PTR_ERR(x))
182 @script:python depends on report@
187 msg="ERR_CAST can be used with %s" % (x)
188 coccilib.report.print_report(p[0], msg)
191 This SmPL excerpt generates entries on the standard output, as
194 /home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
195 /home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
196 /home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg
199 Detailed description of the 'patch' mode
200 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
202 When the 'patch' mode is available, it proposes a fix for each problem
208 make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci
210 will execute the following part of the SmPL script.
213 @ depends on !context && patch && !org && !report @
217 - ERR_PTR(PTR_ERR(x))
221 This SmPL excerpt generates patch hunks on the standard output, as
224 diff -u -p a/crypto/ctr.c b/crypto/ctr.c
225 --- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
226 +++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
227 @@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
228 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
229 CRYPTO_ALG_TYPE_MASK);
231 - return ERR_PTR(PTR_ERR(alg));
232 + return ERR_CAST(alg);
234 /* Block size must be >= 4 bytes. */
237 Detailed description of the 'context' mode
238 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
240 'context' highlights lines of interest and their context
241 in a diff-like style.
243 NOTE: The diff-like output generated is NOT an applicable patch. The
244 intent of the 'context' mode is to highlight the important lines
245 (annotated with minus, '-') and gives some surrounding context
246 lines around. This output can be used with the diff mode of
247 Emacs to review the code.
252 make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
254 will execute the following part of the SmPL script.
257 @ depends on context && !patch && !org && !report@
261 * ERR_PTR(PTR_ERR(x))
264 This SmPL excerpt generates diff hunks on the standard output, as
267 diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
268 --- /home/user/linux/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
270 @@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
271 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
272 CRYPTO_ALG_TYPE_MASK);
274 - return ERR_PTR(PTR_ERR(alg));
276 /* Block size must be >= 4 bytes. */
279 Detailed description of the 'org' mode
280 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
282 'org' generates a report in the Org mode format of Emacs.
287 make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
289 will execute the following part of the SmPL script.
292 @r depends on !context && !patch && (org || report)@
297 ERR_PTR@p(PTR_ERR(x))
299 @script:python depends on org@
304 msg="ERR_CAST can be used with %s" % (x)
305 msg_safe=msg.replace("[","@(").replace("]",")")
306 coccilib.org.print_todo(p[0], msg_safe)
309 This SmPL excerpt generates Org entries on the standard output, as
312 * TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
313 * TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
314 * TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]