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Based on kernel version 3.15.4. Page generated on 2014-07-07 09:00 EST.

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	
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.
13	
14	Coccinelle is available through the package manager
15	of many distributions, e.g. :
16	
17	 - Debian
18	 - Fedora
19	 - Ubuntu
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	
29	Information and tips about Coccinelle are also provided on the wiki
30	pages at http://cocci.ekstranet.diku.dk/wiki/doku.php
31	
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	
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	
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>'.
50	
51	'patch' proposes a fix, when possible.
52	
53	'report' generates a list in the following format:
54	  file:line:column-column: message
55	
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	
61	Note that not all semantic patches implement all modes. For easy use
62	of Coccinelle, the default mode is "report".
63	
64	Two other modes provide some common combinations of these modes.
65	
66	'chain' tries the previous modes in the order above until one succeeds.
67	
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.
71	
72	Examples:
73		To make a report for every semantic patch, run the following command:
74	
75			make coccicheck MODE=report
76	
77		To produce patches, run:
78	
79			make coccicheck MODE=patch
80	
81	
82	The coccicheck target applies every semantic patch available in the
83	sub-directories of 'scripts/coccinelle' to the entire Linux kernel.
84	
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.
88	
89	As any static code analyzer, Coccinelle produces false
90	positives. Thus, reports must be carefully checked, and patches
91	reviewed.
92	
93	To enable verbose messages set the V= variable, for example:
94	
95	   make coccicheck MODE=report V=1
96	
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:
99	
100	   make coccicheck MODE=report J=4
101	
102	
103	 Using Coccinelle with a single semantic patch
104	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
105	
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.
109	
110	For instance:
111	
112		make coccicheck COCCI=<my_SP.cocci> MODE=patch
113	or
114		make coccicheck COCCI=<my_SP.cocci> MODE=report
115	
116	
117	 Controlling Which Files are Processed by Coccinelle
118	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
119	By default the entire kernel source tree is checked.
120	
121	To apply Coccinelle to a specific directory, M= can be used.
122	For example, to check drivers/net/wireless/ one may write:
123	
124	    make coccicheck M=drivers/net/wireless/
125	
126	To apply Coccinelle on a file basis, instead of a directory basis, the
127	following command may be used:
128	
129	    make C=1 CHECK="scripts/coccicheck"
130	
131	To check only newly edited code, use the value 2 for the C flag, i.e.
132	
133	    make C=2 CHECK="scripts/coccicheck"
134	
135	In these modes, which works on a file basis, there is no information
136	about semantic patches displayed, and no commit message proposed.
137	
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.
141	
142	The "report" mode is the default. You can select another one with the
143	MODE variable explained above.
144	
145	 Additional flags
146	~~~~~~~~~~~~~~~~~~
147	
148	Additional flags can be passed to spatch through the SPFLAGS
149	variable.
150	
151	    make SPFLAGS=--use-glimpse coccicheck
152	    make SPFLAGS=--use-idutils coccicheck
153	
154	See spatch --help to learn more about spatch options.
155	
156	Note that the '--use-glimpse' and '--use-idutils' options
157	require external tools for indexing the code. None of them is
158	thus active by default. However, by indexing the code with
159	one of these tools, and according to the cocci file used,
160	spatch could proceed the entire code base more quickly.
161	
162	 Proposing new semantic patches
163	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
164	
165	New semantic patches can be proposed and submitted by kernel
166	developers. For sake of clarity, they should be organized in the
167	sub-directories of 'scripts/coccinelle/'.
168	
169	
170	 Detailed description of the 'report' mode
171	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
172	
173	'report' generates a list in the following format:
174	  file:line:column-column: message
175	
176	Example:
177	
178	Running
179	
180		make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
181	
182	will execute the following part of the SmPL script.
183	
184	<smpl>
185	@r depends on !context && !patch && (org || report)@
186	expression x;
187	position p;
188	@@
189	
190	 ERR_PTR@p(PTR_ERR(x))
191	
192	@script:python depends on report@
193	p << r.p;
194	x << r.x;
195	@@
196	
197	msg="ERR_CAST can be used with %s" % (x)
198	coccilib.report.print_report(p[0], msg)
199	</smpl>
200	
201	This SmPL excerpt generates entries on the standard output, as
202	illustrated below:
203	
204	/home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
205	/home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
206	/home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg
207	
208	
209	 Detailed description of the 'patch' mode
210	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
211	
212	When the 'patch' mode is available, it proposes a fix for each problem
213	identified.
214	
215	Example:
216	
217	Running
218		make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci
219	
220	will execute the following part of the SmPL script.
221	
222	<smpl>
223	@ depends on !context && patch && !org && !report @
224	expression x;
225	@@
226	
227	- ERR_PTR(PTR_ERR(x))
228	+ ERR_CAST(x)
229	</smpl>
230	
231	This SmPL excerpt generates patch hunks on the standard output, as
232	illustrated below:
233	
234	diff -u -p a/crypto/ctr.c b/crypto/ctr.c
235	--- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
236	+++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
237	@@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
238	 	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
239	 				  CRYPTO_ALG_TYPE_MASK);
240	 	if (IS_ERR(alg))
241	-		return ERR_PTR(PTR_ERR(alg));
242	+		return ERR_CAST(alg);
243	 
244	 	/* Block size must be >= 4 bytes. */
245	 	err = -EINVAL;
246	
247	 Detailed description of the 'context' mode
248	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
249	
250	'context' highlights lines of interest and their context
251	in a diff-like style.
252	
253	NOTE: The diff-like output generated is NOT an applicable patch. The
254	      intent of the 'context' mode is to highlight the important lines
255	      (annotated with minus, '-') and gives some surrounding context
256	      lines around. This output can be used with the diff mode of
257	      Emacs to review the code.
258	
259	Example:
260	
261	Running
262		make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
263	
264	will execute the following part of the SmPL script.
265	
266	<smpl>
267	@ depends on context && !patch && !org && !report@
268	expression x;
269	@@
270	
271	* ERR_PTR(PTR_ERR(x))
272	</smpl>
273	
274	This SmPL excerpt generates diff hunks on the standard output, as
275	illustrated below:
276	
277	diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
278	--- /home/user/linux/crypto/ctr.c	2010-05-26 10:49:38.000000000 +0200
279	+++ /tmp/nothing
280	@@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
281	 	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
282	 				  CRYPTO_ALG_TYPE_MASK);
283	 	if (IS_ERR(alg))
284	-		return ERR_PTR(PTR_ERR(alg));
285	 
286	 	/* Block size must be >= 4 bytes. */
287	 	err = -EINVAL;
288	
289	 Detailed description of the 'org' mode
290	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
291	
292	'org' generates a report in the Org mode format of Emacs.
293	
294	Example:
295	
296	Running
297		make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
298	
299	will execute the following part of the SmPL script.
300	
301	<smpl>
302	@r depends on !context && !patch && (org || report)@
303	expression x;
304	position p;
305	@@
306	
307	 ERR_PTR@p(PTR_ERR(x))
308	
309	@script:python depends on org@
310	p << r.p;
311	x << r.x;
312	@@
313	
314	msg="ERR_CAST can be used with %s" % (x)
315	msg_safe=msg.replace("[","@(").replace("]",")")
316	coccilib.org.print_todo(p[0], msg_safe)
317	</smpl>
318	
319	This SmPL excerpt generates Org entries on the standard output, as
320	illustrated below:
321	
322	* TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
323	* TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
324	* TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]
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