Documentation/coccinelle.txt - arm/linux - Git at Google

 Copyright 2010 Nicolas Palix <npalix@diku.dk>
 Copyright 2010 Julia Lawall <julia@diku.dk>
 Copyright 2010 Gilles Muller <Gilles.Muller@lip6.fr>


  Getting Coccinelle
 ~~~~~~~~~~~~~~~~~~~~

 The semantic patches included in the kernel use the 'virtual rule'
 feature which was introduced in Coccinelle version 0.1.11.

 Coccinelle (>=0.2.0) is available through the package manager
 of many distributions, e.g. :

  - Debian (>=squeeze)
  - Fedora (>=13)
  - Ubuntu (>=10.04 Lucid Lynx)
  - OpenSUSE
  - Arch Linux
  - NetBSD
  - FreeBSD


 You can get the latest version released from the Coccinelle homepage at
 http://coccinelle.lip6.fr/

 Information and tips about Coccinelle are also provided on the wiki
 pages at http://cocci.ekstranet.diku.dk/wiki/doku.php

 Once you have it, run the following command:

      	./configure
         make

 as a regular user, and install it with

         sudo make install

 The semantic patches in the kernel will work best with Coccinelle version
 0.2.4 or later.  Using earlier versions may incur some parse errors in the
 semantic patch code, but any results that are obtained should still be
 correct.

  Using Coccinelle on the Linux kernel
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 A Coccinelle-specific target is defined in the top level
 Makefile. This target is named 'coccicheck' and calls the 'coccicheck'
 front-end in the 'scripts' directory.

 Four basic modes are defined: patch, report, context, and org. The mode to
 use is specified by setting the MODE variable with 'MODE=<mode>'.

 'patch' proposes a fix, when possible.

 'report' generates a list in the following format:
   file:line:column-column: message

 'context' highlights lines of interest and their context in a
 diff-like style.Lines of interest are indicated with '-'.

 'org' generates a report in the Org mode format of Emacs.

 Note that not all semantic patches implement all modes. For easy use
 of Coccinelle, the default mode is "report".

 Two other modes provide some common combinations of these modes.

 'chain' tries the previous modes in the order above until one succeeds.

 'rep+ctxt' runs successively the report mode and the context mode.
 	   It should be used with the C option (described later)
 	   which checks the code on a file basis.

 Examples:
 	To make a report for every semantic patch, run the following command:

 		make coccicheck MODE=report

 	To produce patches, run:

 		make coccicheck MODE=patch


 The coccicheck target applies every semantic patch available in the
 sub-directories of 'scripts/coccinelle' to the entire Linux kernel.

 For each semantic patch, a commit message is proposed.  It gives a
 description of the problem being checked by the semantic patch, and
 includes a reference to Coccinelle.

 As any static code analyzer, Coccinelle produces false
 positives. Thus, reports must be carefully checked, and patches
 reviewed.

 To enable verbose messages set the V= variable, for example:

    make coccicheck MODE=report V=1

 By default, coccicheck tries to run as parallel as possible. To change
 the parallelism, set the J= variable. For example, to run across 4 CPUs:

    make coccicheck MODE=report J=4


  Using Coccinelle with a single semantic patch
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 The optional make variable COCCI can be used to check a single
 semantic patch. In that case, the variable must be initialized with
 the name of the semantic patch to apply.

 For instance:

 	make coccicheck COCCI=<my_SP.cocci> MODE=patch
 or
 	make coccicheck COCCI=<my_SP.cocci> MODE=report


  Controlling Which Files are Processed by Coccinelle
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 By default the entire kernel source tree is checked.

 To apply Coccinelle to a specific directory, M= can be used.
 For example, to check drivers/net/wireless/ one may write:

     make coccicheck M=drivers/net/wireless/

 To apply Coccinelle on a file basis, instead of a directory basis, the
 following command may be used:

     make C=1 CHECK="scripts/coccicheck"

 To check only newly edited code, use the value 2 for the C flag, i.e.

     make C=2 CHECK="scripts/coccicheck"

 In these modes, which works on a file basis, there is no information
 about semantic patches displayed, and no commit message proposed.

 This runs every semantic patch in scripts/coccinelle by default. The
 COCCI variable may additionally be used to only apply a single
 semantic patch as shown in the previous section.

 The "report" mode is the default. You can select another one with the
 MODE variable explained above.

  Additional flags
 ~~~~~~~~~~~~~~~~~~

 Additional flags can be passed to spatch through the SPFLAGS
 variable.

     make SPFLAGS=--use-glimpse coccicheck
     make SPFLAGS=--use-idutils coccicheck

 See spatch --help to learn more about spatch options.

 Note that the '--use-glimpse' and '--use-idutils' options
 require external tools for indexing the code. None of them is
 thus active by default. However, by indexing the code with
 one of these tools, and according to the cocci file used,
 spatch could proceed the entire code base more quickly.

  Proposing new semantic patches
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 New semantic patches can be proposed and submitted by kernel
 developers. For sake of clarity, they should be organized in the
 sub-directories of 'scripts/coccinelle/'.


  Detailed description of the 'report' mode
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 'report' generates a list in the following format:
   file:line:column-column: message

 Example:

 Running

 	make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci

 will execute the following part of the SmPL script.

 <smpl>
 @r depends on !context && !patch && (org || report)@
 expression x;
 position p;
 @@

  ERR_PTR@p(PTR_ERR(x))

 @script:python depends on report@
 p << r.p;
 x << r.x;
 @@

 msg="ERR_CAST can be used with %s" % (x)
 coccilib.report.print_report(p[0], msg)
 </smpl>

 This SmPL excerpt generates entries on the standard output, as
 illustrated below:

 /home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
 /home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
 /home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg


  Detailed description of the 'patch' mode
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 When the 'patch' mode is available, it proposes a fix for each problem
 identified.

 Example:

 Running
 	make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci

 will execute the following part of the SmPL script.

 <smpl>
 @ depends on !context && patch && !org && !report @
 expression x;
 @@

 - ERR_PTR(PTR_ERR(x))
 + ERR_CAST(x)
 </smpl>

 This SmPL excerpt generates patch hunks on the standard output, as
 illustrated below:

 diff -u -p a/crypto/ctr.c b/crypto/ctr.c
 --- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
 +++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
 @@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
  	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
  				  CRYPTO_ALG_TYPE_MASK);
  	if (IS_ERR(alg))
 -		return ERR_PTR(PTR_ERR(alg));
 +		return ERR_CAST(alg);

  	/* Block size must be >= 4 bytes. */
  	err = -EINVAL;

  Detailed description of the 'context' mode
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 'context' highlights lines of interest and their context
 in a diff-like style.

 NOTE: The diff-like output generated is NOT an applicable patch. The
       intent of the 'context' mode is to highlight the important lines
       (annotated with minus, '-') and gives some surrounding context
       lines around. This output can be used with the diff mode of
       Emacs to review the code.

 Example:

 Running
 	make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci

 will execute the following part of the SmPL script.

 <smpl>
 @ depends on context && !patch && !org && !report@
 expression x;
 @@

 * ERR_PTR(PTR_ERR(x))
 </smpl>

 This SmPL excerpt generates diff hunks on the standard output, as
 illustrated below:

 diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
 --- /home/user/linux/crypto/ctr.c	2010-05-26 10:49:38.000000000 +0200
 +++ /tmp/nothing
 @@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
  	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
  				  CRYPTO_ALG_TYPE_MASK);
  	if (IS_ERR(alg))
 -		return ERR_PTR(PTR_ERR(alg));

  	/* Block size must be >= 4 bytes. */
  	err = -EINVAL;

  Detailed description of the 'org' mode
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 'org' generates a report in the Org mode format of Emacs.

 Example:

 Running
 	make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci

 will execute the following part of the SmPL script.

 <smpl>
 @r depends on !context && !patch && (org || report)@
 expression x;
 position p;
 @@

  ERR_PTR@p(PTR_ERR(x))

 @script:python depends on org@
 p << r.p;
 x << r.x;
 @@

 msg="ERR_CAST can be used with %s" % (x)
 msg_safe=msg.replace("[","@(").replace("]",")")
 coccilib.org.print_todo(p[0], msg_safe)
 </smpl>

 This SmPL excerpt generates Org entries on the standard output, as
 illustrated below:

 * TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
 * TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
 * TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]
	Copyright 2010 Nicolas Palix <npalix@diku.dk>
	Copyright 2010 Julia Lawall <julia@diku.dk>
	Copyright 2010 Gilles Muller <Gilles.Muller@lip6.fr>


	Getting Coccinelle
	~~~~~~~~~~~~~~~~~~~~

	The semantic patches included in the kernel use the 'virtual rule'
	feature which was introduced in Coccinelle version 0.1.11.

	Coccinelle (>=0.2.0) is available through the package manager
	of many distributions, e.g. :

	- Debian (>=squeeze)
	- Fedora (>=13)
	- Ubuntu (>=10.04 Lucid Lynx)
	- OpenSUSE
	- Arch Linux
	- NetBSD
	- FreeBSD


	You can get the latest version released from the Coccinelle homepage at
	http://coccinelle.lip6.fr/

	Information and tips about Coccinelle are also provided on the wiki
	pages at http://cocci.ekstranet.diku.dk/wiki/doku.php

	Once you have it, run the following command:

	./configure
	make

	as a regular user, and install it with

	sudo make install

	The semantic patches in the kernel will work best with Coccinelle version
	0.2.4 or later. Using earlier versions may incur some parse errors in the
	semantic patch code, but any results that are obtained should still be
	correct.

	Using Coccinelle on the Linux kernel
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	A Coccinelle-specific target is defined in the top level
	Makefile. This target is named 'coccicheck' and calls the 'coccicheck'
	front-end in the 'scripts' directory.

	Four basic modes are defined: patch, report, context, and org. The mode to
	use is specified by setting the MODE variable with 'MODE=<mode>'.

	'patch' proposes a fix, when possible.

	'report' generates a list in the following format:
	file:line:column-column: message

	'context' highlights lines of interest and their context in a
	diff-like style.Lines of interest are indicated with '-'.

	'org' generates a report in the Org mode format of Emacs.

	Note that not all semantic patches implement all modes. For easy use
	of Coccinelle, the default mode is "report".

	Two other modes provide some common combinations of these modes.

	'chain' tries the previous modes in the order above until one succeeds.

	'rep+ctxt' runs successively the report mode and the context mode.
	It should be used with the C option (described later)
	which checks the code on a file basis.

	Examples:
	To make a report for every semantic patch, run the following command:

	make coccicheck MODE=report

	To produce patches, run:

	make coccicheck MODE=patch


	The coccicheck target applies every semantic patch available in the
	sub-directories of 'scripts/coccinelle' to the entire Linux kernel.

	For each semantic patch, a commit message is proposed. It gives a
	description of the problem being checked by the semantic patch, and
	includes a reference to Coccinelle.

	As any static code analyzer, Coccinelle produces false
	positives. Thus, reports must be carefully checked, and patches
	reviewed.

	To enable verbose messages set the V= variable, for example:

	make coccicheck MODE=report V=1

	By default, coccicheck tries to run as parallel as possible. To change
	the parallelism, set the J= variable. For example, to run across 4 CPUs:

	make coccicheck MODE=report J=4


	Using Coccinelle with a single semantic patch
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	The optional make variable COCCI can be used to check a single
	semantic patch. In that case, the variable must be initialized with
	the name of the semantic patch to apply.

	For instance:

	make coccicheck COCCI=<my_SP.cocci> MODE=patch
	or
	make coccicheck COCCI=<my_SP.cocci> MODE=report


	Controlling Which Files are Processed by Coccinelle
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	By default the entire kernel source tree is checked.

	To apply Coccinelle to a specific directory, M= can be used.
	For example, to check drivers/net/wireless/ one may write:

	make coccicheck M=drivers/net/wireless/

	To apply Coccinelle on a file basis, instead of a directory basis, the
	following command may be used:

	make C=1 CHECK="scripts/coccicheck"

	To check only newly edited code, use the value 2 for the C flag, i.e.

	make C=2 CHECK="scripts/coccicheck"

	In these modes, which works on a file basis, there is no information
	about semantic patches displayed, and no commit message proposed.

	This runs every semantic patch in scripts/coccinelle by default. The
	COCCI variable may additionally be used to only apply a single
	semantic patch as shown in the previous section.

	The "report" mode is the default. You can select another one with the
	MODE variable explained above.

	Additional flags
	~~~~~~~~~~~~~~~~~~

	Additional flags can be passed to spatch through the SPFLAGS
	variable.

	make SPFLAGS=--use-glimpse coccicheck
	make SPFLAGS=--use-idutils coccicheck

	See spatch --help to learn more about spatch options.

	Note that the '--use-glimpse' and '--use-idutils' options
	require external tools for indexing the code. None of them is
	thus active by default. However, by indexing the code with
	one of these tools, and according to the cocci file used,
	spatch could proceed the entire code base more quickly.

	Proposing new semantic patches
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	New semantic patches can be proposed and submitted by kernel
	developers. For sake of clarity, they should be organized in the
	sub-directories of 'scripts/coccinelle/'.


	Detailed description of the 'report' mode
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	'report' generates a list in the following format:
	file:line:column-column: message

	Example:

	Running

	make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci

	will execute the following part of the SmPL script.

	<smpl>
	@r depends on !context && !patch && (org \|\| report)@
	expression x;
	position p;
	@@

	ERR_PTR@p(PTR_ERR(x))

	@script:python depends on report@
	p << r.p;
	x << r.x;
	@@

	msg="ERR_CAST can be used with %s" % (x)
	coccilib.report.print_report(p[0], msg)
	</smpl>

	This SmPL excerpt generates entries on the standard output, as
	illustrated below:

	/home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
	/home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
	/home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg


	Detailed description of the 'patch' mode
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	When the 'patch' mode is available, it proposes a fix for each problem
	identified.

	Example:

	Running
	make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci

	will execute the following part of the SmPL script.

	<smpl>
	@ depends on !context && patch && !org && !report @
	expression x;
	@@

	- ERR_PTR(PTR_ERR(x))
	+ ERR_CAST(x)
	</smpl>

	This SmPL excerpt generates patch hunks on the standard output, as
	illustrated below:

	diff -u -p a/crypto/ctr.c b/crypto/ctr.c
	--- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
	+++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
	@@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
	CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
	- return ERR_PTR(PTR_ERR(alg));
	+ return ERR_CAST(alg);

	/* Block size must be >= 4 bytes. */
	err = -EINVAL;

	Detailed description of the 'context' mode
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	'context' highlights lines of interest and their context
	in a diff-like style.

	NOTE: The diff-like output generated is NOT an applicable patch. The
	intent of the 'context' mode is to highlight the important lines
	(annotated with minus, '-') and gives some surrounding context
	lines around. This output can be used with the diff mode of
	Emacs to review the code.

	Example:

	Running
	make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci

	will execute the following part of the SmPL script.

	<smpl>
	@ depends on context && !patch && !org && !report@
	expression x;
	@@

	* ERR_PTR(PTR_ERR(x))
	</smpl>

	This SmPL excerpt generates diff hunks on the standard output, as
	illustrated below:

	diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
	--- /home/user/linux/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
	+++ /tmp/nothing
	@@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
	alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
	CRYPTO_ALG_TYPE_MASK);
	if (IS_ERR(alg))
	- return ERR_PTR(PTR_ERR(alg));

	/* Block size must be >= 4 bytes. */
	err = -EINVAL;

	Detailed description of the 'org' mode
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

	'org' generates a report in the Org mode format of Emacs.

	Example:

	Running
	make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci

	will execute the following part of the SmPL script.

	<smpl>
	@r depends on !context && !patch && (org \|\| report)@
	expression x;
	position p;
	@@

	ERR_PTR@p(PTR_ERR(x))

	@script:python depends on org@
	p << r.p;
	x << r.x;
	@@

	msg="ERR_CAST can be used with %s" % (x)
	msg_safe=msg.replace("[","@(").replace("]",")")
	coccilib.org.print_todo(p[0], msg_safe)
	</smpl>

	This SmPL excerpt generates Org entries on the standard output, as
	illustrated below:

	* TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
	* TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
	* TODO [[view:/home/user/linux/crypto/xts.c::face=ovl-face1::linb=227::colb=9::cole=16][ERR_CAST can be used with alg]]