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 Coccinelle parallelization
98 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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:
103 make coccicheck MODE=report J=4
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.
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.
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.
118 Using Coccinelle with a single semantic patch
119 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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.
127 make coccicheck COCCI=<my_SP.cocci> MODE=patch
129 make coccicheck COCCI=<my_SP.cocci> MODE=report
132 Controlling Which Files are Processed by Coccinelle
133 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
134 By default the entire kernel source tree is checked.
136 To apply Coccinelle to a specific directory, M= can be used.
137 For example, to check drivers/net/wireless/ one may write:
139 make coccicheck M=drivers/net/wireless/
141 To apply Coccinelle on a file basis, instead of a directory basis, the
142 following command may be used:
144 make C=1 CHECK="scripts/coccicheck"
146 To check only newly edited code, use the value 2 for the C flag, i.e.
148 make C=2 CHECK="scripts/coccicheck"
150 In these modes, which works on a file basis, there is no information
151 about semantic patches displayed, and no commit message proposed.
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.
157 The "report" mode is the default. You can select another one with the
158 MODE variable explained above.
163 Additional flags can be passed to spatch through the SPFLAGS
164 variable. This works as Coccinelle respects the last flags
165 given to it when options are in conflict.
167 make SPFLAGS=--use-glimpse coccicheck
168 make SPFLAGS=--use-idutils coccicheck
170 See spatch --help to learn more about spatch options.
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.
178 Proposing new semantic patches
179 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
181 New semantic patches can be proposed and submitted by kernel
182 developers. For sake of clarity, they should be organized in the
183 sub-directories of 'scripts/coccinelle/'.
186 Detailed description of the 'report' mode
187 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
189 'report' generates a list in the following format:
190 file:line:column-column: message
196 make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
198 will execute the following part of the SmPL script.
201 @r depends on !context && !patch && (org || report)@
206 ERR_PTR@p(PTR_ERR(x))
208 @script:python depends on report@
213 msg="ERR_CAST can be used with %s" % (x)
214 coccilib.report.print_report(p[0], msg)
217 This SmPL excerpt generates entries on the standard output, as
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
225 Detailed description of the 'patch' mode
226 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
228 When the 'patch' mode is available, it proposes a fix for each problem
234 make coccicheck MODE=patch 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))
247 This SmPL excerpt generates patch hunks on the standard output, as
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);
257 - return ERR_PTR(PTR_ERR(alg));
258 + return ERR_CAST(alg);
260 /* Block size must be >= 4 bytes. */
263 Detailed description of the 'context' mode
264 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
266 'context' highlights lines of interest and their context
267 in a diff-like style.
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.
278 make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
280 will execute the following part of the SmPL script.
283 @ depends on context && !patch && !org && !report@
287 * ERR_PTR(PTR_ERR(x))
290 This SmPL excerpt generates diff hunks on the standard output, as
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
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);
300 - return ERR_PTR(PTR_ERR(alg));
302 /* Block size must be >= 4 bytes. */
305 Detailed description of the 'org' mode
306 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
308 'org' generates a report in the Org mode format of Emacs.
313 make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
315 will execute the following part of the SmPL script.
318 @r depends on !context && !patch && (org || report)@
323 ERR_PTR@p(PTR_ERR(x))
325 @script:python depends on org@
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)
335 This SmPL excerpt generates Org entries on the standard output, as
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]]