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 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.
14 Coccinelle is available through the package manager
15 of many distributions, e.g. :
26 You can get the latest version released from the Coccinelle homepage at
27 http://coccinelle.lip6.fr/
29 Information and tips about Coccinelle are also provided on the wiki
30 pages at http://cocci.ekstranet.diku.dk/wiki/doku.php
32 Once you have it, run the following command:
37 as a regular user, and install it with
41 Using Coccinelle on the Linux kernel
42 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.
48 Four basic modes are defined: patch, report, context, and org. The mode to
49 use is specified by setting the MODE variable with 'MODE=<mode>'.
51 'patch' proposes a fix, when possible.
53 'report' generates a list in the following format:
54 file:line:column-column: message
56 'context' highlights lines of interest and their context in a
57 diff-like style.Lines of interest are indicated with '-'.
59 'org' generates a report in the Org mode format of Emacs.
61 Note that not all semantic patches implement all modes. For easy use
62 of Coccinelle, the default mode is "report".
64 Two other modes provide some common combinations of these modes.
66 'chain' tries the previous modes in the order above until one succeeds.
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.
73 To make a report for every semantic patch, run the following command:
75 make coccicheck MODE=report
77 To produce patches, run:
79 make coccicheck MODE=patch
82 The coccicheck target applies every semantic patch available in the
83 sub-directories of 'scripts/coccinelle' to the entire Linux kernel.
85 For each semantic patch, a commit message is proposed. It gives a
86 description of the problem being checked by the semantic patch, and
87 includes a reference to Coccinelle.
89 As any static code analyzer, Coccinelle produces false
90 positives. Thus, reports must be carefully checked, and patches
93 To enable verbose messages set the V= variable, for example:
95 make coccicheck MODE=report V=1
97 By default, coccicheck tries to run as parallel as possible. To change
98 the parallelism, set the J= variable. For example, to run across 4 CPUs:
100 make coccicheck MODE=report J=4
103 Using Coccinelle with a single semantic patch
104 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
106 The optional make variable COCCI can be used to check a single
107 semantic patch. In that case, the variable must be initialized with
108 the name of the semantic patch to apply.
112 make coccicheck COCCI=<my_SP.cocci> MODE=patch
114 make coccicheck COCCI=<my_SP.cocci> MODE=report
117 Controlling Which Files are Processed by Coccinelle
118 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
119 By default the entire kernel source tree is checked.
121 To apply Coccinelle to a specific directory, M= can be used.
122 For example, to check drivers/net/wireless/ one may write:
124 make coccicheck M=drivers/net/wireless/
126 To apply Coccinelle on a file basis, instead of a directory basis, the
127 following command may be used:
129 make C=1 CHECK="scripts/coccicheck"
131 To check only newly edited code, use the value 2 for the C flag, i.e.
133 make C=2 CHECK="scripts/coccicheck"
135 In these modes, which works on a file basis, there is no information
136 about semantic patches displayed, and no commit message proposed.
138 This runs every semantic patch in scripts/coccinelle by default. The
139 COCCI variable may additionally be used to only apply a single
140 semantic patch as shown in the previous section.
142 The "report" mode is the default. You can select another one with the
143 MODE variable explained above.
148 Additional flags can be passed to spatch through the SPFLAGS
149 variable. This works as Coccinelle respects the last flags
150 given to it when options are in conflict.
152 make SPFLAGS=--use-glimpse coccicheck
153 make SPFLAGS=--use-idutils coccicheck
155 See spatch --help to learn more about spatch options.
157 Note that the '--use-glimpse' and '--use-idutils' options
158 require external tools for indexing the code. None of them is
159 thus active by default. However, by indexing the code with
160 one of these tools, and according to the cocci file used,
161 spatch could proceed the entire code base more quickly.
163 Proposing new semantic patches
164 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
166 New semantic patches can be proposed and submitted by kernel
167 developers. For sake of clarity, they should be organized in the
168 sub-directories of 'scripts/coccinelle/'.
171 Detailed description of the 'report' mode
172 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
174 'report' generates a list in the following format:
175 file:line:column-column: message
181 make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
183 will execute the following part of the SmPL script.
186 @r depends on !context && !patch && (org || report)@
191 ERR_PTR@p(PTR_ERR(x))
193 @script:python depends on report@
198 msg="ERR_CAST can be used with %s" % (x)
199 coccilib.report.print_report(p[0], msg)
202 This SmPL excerpt generates entries on the standard output, as
205 /home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
206 /home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
207 /home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg
210 Detailed description of the 'patch' mode
211 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
213 When the 'patch' mode is available, it proposes a fix for each problem
219 make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci
221 will execute the following part of the SmPL script.
224 @ depends on !context && patch && !org && !report @
228 - ERR_PTR(PTR_ERR(x))
232 This SmPL excerpt generates patch hunks on the standard output, as
235 diff -u -p a/crypto/ctr.c b/crypto/ctr.c
236 --- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
237 +++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
238 @@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
239 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
240 CRYPTO_ALG_TYPE_MASK);
242 - return ERR_PTR(PTR_ERR(alg));
243 + return ERR_CAST(alg);
245 /* Block size must be >= 4 bytes. */
248 Detailed description of the 'context' mode
249 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
251 'context' highlights lines of interest and their context
252 in a diff-like style.
254 NOTE: The diff-like output generated is NOT an applicable patch. The
255 intent of the 'context' mode is to highlight the important lines
256 (annotated with minus, '-') and gives some surrounding context
257 lines around. This output can be used with the diff mode of
258 Emacs to review the code.
263 make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
265 will execute the following part of the SmPL script.
268 @ depends on context && !patch && !org && !report@
272 * ERR_PTR(PTR_ERR(x))
275 This SmPL excerpt generates diff hunks on the standard output, as
278 diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
279 --- /home/user/linux/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
281 @@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
282 alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
283 CRYPTO_ALG_TYPE_MASK);
285 - return ERR_PTR(PTR_ERR(alg));
287 /* Block size must be >= 4 bytes. */
290 Detailed description of the 'org' mode
291 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
293 'org' generates a report in the Org mode format of Emacs.
298 make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
300 will execute the following part of the SmPL script.
303 @r depends on !context && !patch && (org || report)@
308 ERR_PTR@p(PTR_ERR(x))
310 @script:python depends on org@
315 msg="ERR_CAST can be used with %s" % (x)
316 msg_safe=msg.replace("[","@(").replace("]",")")
317 coccilib.org.print_todo(p[0], msg_safe)
320 This SmPL excerpt generates Org entries on the standard output, as
323 * TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
324 * TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
325 * TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]