4b9033a334
No textual changes have been made, but the formatting has obviously been tweaked. Cc: Michal Marek <mmarek@suse.com> Cc: Gilles Muller <Gilles.Muller@lip6.fr> Acked-by: Nicolas Palix <nicolas.palix@imag.fr> Acked-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
492 lines
16 KiB
ReStructuredText
492 lines
16 KiB
ReStructuredText
.. Copyright 2010 Nicolas Palix <npalix@diku.dk>
|
|
.. Copyright 2010 Julia Lawall <julia@diku.dk>
|
|
.. Copyright 2010 Gilles Muller <Gilles.Muller@lip6.fr>
|
|
|
|
.. highlight:: none
|
|
|
|
Coccinelle
|
|
==========
|
|
|
|
Coccinelle is a tool for pattern matching and text transformation that has
|
|
many uses in kernel development, including the application of complex,
|
|
tree-wide patches and detection of problematic programming patterns.
|
|
|
|
Getting Coccinelle
|
|
-------------------
|
|
|
|
The semantic patches included in the kernel use features and options
|
|
which are provided by Coccinelle version 1.0.0-rc11 and above.
|
|
Using earlier versions will fail as the option names used by
|
|
the Coccinelle files and coccicheck have been updated.
|
|
|
|
Coccinelle is available through the package manager
|
|
of many distributions, e.g. :
|
|
|
|
- Debian
|
|
- Fedora
|
|
- Ubuntu
|
|
- 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
|
|
|
|
Supplemental documentation
|
|
---------------------------
|
|
|
|
For supplemental documentation refer to the wiki:
|
|
|
|
https://bottest.wiki.kernel.org/coccicheck
|
|
|
|
The wiki documentation always refers to the linux-next version of the script.
|
|
|
|
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
|
|
|
|
Coccinelle parallelization
|
|
---------------------------
|
|
|
|
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
|
|
|
|
As of Coccinelle 1.0.2 Coccinelle uses Ocaml parmap for parallelization,
|
|
if support for this is detected you will benefit from parmap parallelization.
|
|
|
|
When parmap is enabled coccicheck will enable dynamic load balancing by using
|
|
``--chunksize 1`` argument, this ensures we keep feeding threads with work
|
|
one by one, so that we avoid the situation where most work gets done by only
|
|
a few threads. With dynamic load balancing, if a thread finishes early we keep
|
|
feeding it more work.
|
|
|
|
When parmap is enabled, if an error occurs in Coccinelle, this error
|
|
value is propagated back, the return value of the ``make coccicheck``
|
|
captures this return value.
|
|
|
|
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.
|
|
|
|
Debugging Coccinelle SmPL patches
|
|
---------------------------------
|
|
|
|
Using coccicheck is best as it provides in the spatch command line
|
|
include options matching the options used when we compile the kernel.
|
|
You can learn what these options are by using V=1, you could then
|
|
manually run Coccinelle with debug options added.
|
|
|
|
Alternatively you can debug running Coccinelle against SmPL patches
|
|
by asking for stderr to be redirected to stderr, by default stderr
|
|
is redirected to /dev/null, if you'd like to capture stderr you
|
|
can specify the ``DEBUG_FILE="file.txt"`` option to coccicheck. For
|
|
instance::
|
|
|
|
rm -f cocci.err
|
|
make coccicheck COCCI=scripts/coccinelle/free/kfree.cocci MODE=report DEBUG_FILE=cocci.err
|
|
cat cocci.err
|
|
|
|
You can use SPFLAGS to add debugging flags, for instance you may want to
|
|
add both --profile --show-trying to SPFLAGS when debugging. For instance
|
|
you may want to use::
|
|
|
|
rm -f err.log
|
|
export COCCI=scripts/coccinelle/misc/irqf_oneshot.cocci
|
|
make coccicheck DEBUG_FILE="err.log" MODE=report SPFLAGS="--profile --show-trying" M=./drivers/mfd/arizona-irq.c
|
|
|
|
err.log will now have the profiling information, while stdout will
|
|
provide some progress information as Coccinelle moves forward with
|
|
work.
|
|
|
|
DEBUG_FILE support is only supported when using coccinelle >= 1.2.
|
|
|
|
.cocciconfig support
|
|
--------------------
|
|
|
|
Coccinelle supports reading .cocciconfig for default Coccinelle options that
|
|
should be used every time spatch is spawned, the order of precedence for
|
|
variables for .cocciconfig is as follows:
|
|
|
|
- Your current user's home directory is processed first
|
|
- Your directory from which spatch is called is processed next
|
|
- The directory provided with the --dir option is processed last, if used
|
|
|
|
Since coccicheck runs through make, it naturally runs from the kernel
|
|
proper dir, as such the second rule above would be implied for picking up a
|
|
.cocciconfig when using ``make coccicheck``.
|
|
|
|
``make coccicheck`` also supports using M= targets.If you do not supply
|
|
any M= target, it is assumed you want to target the entire kernel.
|
|
The kernel coccicheck script has::
|
|
|
|
if [ "$KBUILD_EXTMOD" = "" ] ; then
|
|
OPTIONS="--dir $srctree $COCCIINCLUDE"
|
|
else
|
|
OPTIONS="--dir $KBUILD_EXTMOD $COCCIINCLUDE"
|
|
fi
|
|
|
|
KBUILD_EXTMOD is set when an explicit target with M= is used. For both cases
|
|
the spatch --dir argument is used, as such third rule applies when whether M=
|
|
is used or not, and when M= is used the target directory can have its own
|
|
.cocciconfig file. When M= is not passed as an argument to coccicheck the
|
|
target directory is the same as the directory from where spatch was called.
|
|
|
|
If not using the kernel's coccicheck target, keep the above precedence
|
|
order logic of .cocciconfig reading. If using the kernel's coccicheck target,
|
|
override any of the kernel's .coccicheck's settings using SPFLAGS.
|
|
|
|
We help Coccinelle when used against Linux with a set of sensible defaults
|
|
options for Linux with our own Linux .cocciconfig. This hints to coccinelle
|
|
git can be used for ``git grep`` queries over coccigrep. A timeout of 200
|
|
seconds should suffice for now.
|
|
|
|
The options picked up by coccinelle when reading a .cocciconfig do not appear
|
|
as arguments to spatch processes running on your system, to confirm what
|
|
options will be used by Coccinelle run::
|
|
|
|
spatch --print-options-only
|
|
|
|
You can override with your own preferred index option by using SPFLAGS. Take
|
|
note that when there are conflicting options Coccinelle takes precedence for
|
|
the last options passed. Using .cocciconfig is possible to use idutils, however
|
|
given the order of precedence followed by Coccinelle, since the kernel now
|
|
carries its own .cocciconfig, you will need to use SPFLAGS to use idutils if
|
|
desired. See below section "Additional flags" for more details on how to use
|
|
idutils.
|
|
|
|
Additional flags
|
|
----------------
|
|
|
|
Additional flags can be passed to spatch through the SPFLAGS
|
|
variable. This works as Coccinelle respects the last flags
|
|
given to it when options are in conflict. ::
|
|
|
|
make SPFLAGS=--use-glimpse coccicheck
|
|
|
|
Coccinelle supports idutils as well but requires coccinelle >= 1.0.6.
|
|
When no ID file is specified coccinelle assumes your ID database file
|
|
is in the file .id-utils.index on the top level of the kernel, coccinelle
|
|
carries a script scripts/idutils_index.sh which creates the database with::
|
|
|
|
mkid -i C --output .id-utils.index
|
|
|
|
If you have another database filename you can also just symlink with this
|
|
name. ::
|
|
|
|
make SPFLAGS=--use-idutils coccicheck
|
|
|
|
Alternatively you can specify the database filename explicitly, for
|
|
instance::
|
|
|
|
make SPFLAGS="--use-idutils /full-path/to/ID" 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.
|
|
|
|
SmPL patch specific options
|
|
---------------------------
|
|
|
|
SmPL patches can have their own requirements for options passed
|
|
to Coccinelle. SmPL patch specific options can be provided by
|
|
providing them at the top of the SmPL patch, for instance::
|
|
|
|
// Options: --no-includes --include-headers
|
|
|
|
SmPL patch Coccinelle requirements
|
|
----------------------------------
|
|
|
|
As Coccinelle features get added some more advanced SmPL patches
|
|
may require newer versions of Coccinelle. If an SmPL patch requires
|
|
at least a version of Coccinelle, this can be specified as follows,
|
|
as an example if requiring at least Coccinelle >= 1.0.5::
|
|
|
|
// Requires: 1.0.5
|
|
|
|
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]]
|