forked from Minki/linux
dd951fc1b6
Coccinelle supports reading .cocciconfig, the order of precedence for variables for .cocciconfig is as follows: o Your current user's home directory is processed first o Your directory from which spatch is called is processed next o 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. Coccinelle supports both glimpse and idutils. Glimpse had historically provided the best performance, however recent benchmarks reveal idutils is performing just as well. Due to some recent fixes however you however will need at least coccinelle >= 1.0.6 if using idutils. Coccinelle carries a script scripts/idutils_index.sh which creates the idutils database with as follows: mkid -i C --output .id-utils.index If using just "--use-idutils" coccinelle expects your idutils database to be on the top level of the kernel as a file named ".id-utils.index". If you do not use this you can symlink your database file to it, or you can specify the database file following the "--use-idutils" argument. Examples: make SPFLAGS=--use-idutils coccicheck This assumes you have $srctree/.id-utils.index, where $srctree is the top level of the kernel. make SPFLAGS="--use-idutils /full-path/to/ID" coccicheck Here you specify the full path of the idutils ID database. Using .cocciconfig is possible, however given the order of precedence followed by Coccinelle, and since the kernel now carries its own .cocciconfig, you will need to use SPFLAGS to use idutils if desired. v4: o Recommend upgrade for using idutils with coccinelle due to some recent fixes. o Refer to using --print-options-only for testing what options are picked up by .cocciconfig reading. o Expand commit log considerably explaining *why* .cocconfig from two precedence rules are used when using coccicheck, and how to properly override these if needed. o Expand Documentation/coccinelle.txt v3: Expand commit log a bit more Signed-off-by: Luis R. Rodriguez <mcgrof@kernel.org> Acked-by: Julia Lawall <julia.lawall@lip6.fr> Signed-off-by: Michal Marek <mmarek@suse.com>
443 lines
14 KiB
Plaintext
443 lines
14 KiB
Plaintext
Copyright 2010 Nicolas Palix <npalix@diku.dk>
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Copyright 2010 Julia Lawall <julia@diku.dk>
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Copyright 2010 Gilles Muller <Gilles.Muller@lip6.fr>
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Getting Coccinelle
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~~~~~~~~~~~~~~~~~~~~
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The semantic patches included in the kernel use features and options
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which are provided by Coccinelle version 1.0.0-rc11 and above.
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Using earlier versions will fail as the option names used by
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the Coccinelle files and coccicheck have been updated.
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Coccinelle is available through the package manager
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of many distributions, e.g. :
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- Debian
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- Fedora
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- Ubuntu
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- OpenSUSE
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- Arch Linux
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- NetBSD
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- FreeBSD
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You can get the latest version released from the Coccinelle homepage at
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http://coccinelle.lip6.fr/
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Information and tips about Coccinelle are also provided on the wiki
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pages at http://cocci.ekstranet.diku.dk/wiki/doku.php
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Once you have it, run the following command:
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./configure
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make
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as a regular user, and install it with
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sudo make install
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Using Coccinelle on the Linux kernel
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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A Coccinelle-specific target is defined in the top level
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Makefile. This target is named 'coccicheck' and calls the 'coccicheck'
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front-end in the 'scripts' directory.
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Four basic modes are defined: patch, report, context, and org. The mode to
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use is specified by setting the MODE variable with 'MODE=<mode>'.
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'patch' proposes a fix, when possible.
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'report' generates a list in the following format:
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file:line:column-column: message
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'context' highlights lines of interest and their context in a
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diff-like style.Lines of interest are indicated with '-'.
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'org' generates a report in the Org mode format of Emacs.
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Note that not all semantic patches implement all modes. For easy use
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of Coccinelle, the default mode is "report".
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Two other modes provide some common combinations of these modes.
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'chain' tries the previous modes in the order above until one succeeds.
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'rep+ctxt' runs successively the report mode and the context mode.
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It should be used with the C option (described later)
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which checks the code on a file basis.
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Examples:
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To make a report for every semantic patch, run the following command:
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make coccicheck MODE=report
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To produce patches, run:
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make coccicheck MODE=patch
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The coccicheck target applies every semantic patch available in the
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sub-directories of 'scripts/coccinelle' to the entire Linux kernel.
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For each semantic patch, a commit message is proposed. It gives a
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description of the problem being checked by the semantic patch, and
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includes a reference to Coccinelle.
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As any static code analyzer, Coccinelle produces false
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positives. Thus, reports must be carefully checked, and patches
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reviewed.
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To enable verbose messages set the V= variable, for example:
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make coccicheck MODE=report V=1
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Coccinelle parallelization
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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By default, coccicheck tries to run as parallel as possible. To change
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the parallelism, set the J= variable. For example, to run across 4 CPUs:
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make coccicheck MODE=report J=4
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As of Coccinelle 1.0.2 Coccinelle uses Ocaml parmap for parallelization,
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if support for this is detected you will benefit from parmap parallelization.
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When parmap is enabled coccicheck will enable dynamic load balancing by using
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'--chunksize 1' argument, this ensures we keep feeding threads with work
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one by one, so that we avoid the situation where most work gets done by only
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a few threads. With dynamic load balancing, if a thread finishes early we keep
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feeding it more work.
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When parmap is enabled, if an error occurs in Coccinelle, this error
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value is propagated back, the return value of the 'make coccicheck'
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captures this return value.
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Using Coccinelle with a single semantic patch
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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The optional make variable COCCI can be used to check a single
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semantic patch. In that case, the variable must be initialized with
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the name of the semantic patch to apply.
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For instance:
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make coccicheck COCCI=<my_SP.cocci> MODE=patch
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or
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make coccicheck COCCI=<my_SP.cocci> MODE=report
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Controlling Which Files are Processed by Coccinelle
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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By default the entire kernel source tree is checked.
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To apply Coccinelle to a specific directory, M= can be used.
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For example, to check drivers/net/wireless/ one may write:
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make coccicheck M=drivers/net/wireless/
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To apply Coccinelle on a file basis, instead of a directory basis, the
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following command may be used:
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make C=1 CHECK="scripts/coccicheck"
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To check only newly edited code, use the value 2 for the C flag, i.e.
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make C=2 CHECK="scripts/coccicheck"
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In these modes, which works on a file basis, there is no information
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about semantic patches displayed, and no commit message proposed.
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This runs every semantic patch in scripts/coccinelle by default. The
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COCCI variable may additionally be used to only apply a single
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semantic patch as shown in the previous section.
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The "report" mode is the default. You can select another one with the
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MODE variable explained above.
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Debugging Coccinelle SmPL patches
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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Using coccicheck is best as it provides in the spatch command line
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include options matching the options used when we compile the kernel.
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You can learn what these options are by using V=1, you could then
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manually run Coccinelle with debug options added.
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Alternatively you can debug running Coccinelle against SmPL patches
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by asking for stderr to be redirected to stderr, by default stderr
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is redirected to /dev/null, if you'd like to capture stderr you
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can specify the DEBUG_FILE="file.txt" option to coccicheck. For
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instance:
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rm -f cocci.err
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make coccicheck COCCI=scripts/coccinelle/free/kfree.cocci MODE=report DEBUG_FILE=cocci.err
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cat cocci.err
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You can use SPFLAGS to add debugging flags, for instance you may want to
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add both --profile --show-trying to SPFLAGS when debugging. For instance
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you may want to use:
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rm -f err.log
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export COCCI=scripts/coccinelle/misc/irqf_oneshot.cocci
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make coccicheck DEBUG_FILE="err.log" MODE=report SPFLAGS="--profile --show-trying" M=./drivers/mfd/arizona-irq.c
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err.log will now have the profiling information, while stdout will
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provide some progress information as Coccinelle moves forward with
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work.
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DEBUG_FILE support is only supported when using coccinelle >= 1.2.
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.cocciconfig support
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~~~~~~~~~~~~~~~~~~~~~~
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Coccinelle supports reading .cocciconfig for default Coccinelle options that
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should be used every time spatch is spawned, the order of precedence for
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variables for .cocciconfig is as follows:
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o Your current user's home directory is processed first
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o Your directory from which spatch is called is processed next
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o The directory provided with the --dir option is processed last, if used
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Since coccicheck runs through make, it naturally runs from the kernel
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proper dir, as such the second rule above would be implied for picking up a
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.cocciconfig when using 'make coccicheck'.
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'make coccicheck' also supports using M= targets.If you do not supply
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any M= target, it is assumed you want to target the entire kernel.
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The kernel coccicheck script has:
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if [ "$KBUILD_EXTMOD" = "" ] ; then
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OPTIONS="--dir $srctree $COCCIINCLUDE"
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else
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OPTIONS="--dir $KBUILD_EXTMOD $COCCIINCLUDE"
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fi
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KBUILD_EXTMOD is set when an explicit target with M= is used. For both cases
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the spatch --dir argument is used, as such third rule applies when whether M=
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is used or not, and when M= is used the target directory can have its own
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.cocciconfig file. When M= is not passed as an argument to coccicheck the
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target directory is the same as the directory from where spatch was called.
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If not using the kernel's coccicheck target, keep the above precedence
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order logic of .cocciconfig reading. If using the kernel's coccicheck target,
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override any of the kernel's .coccicheck's settings using SPFLAGS.
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We help Coccinelle when used against Linux with a set of sensible defaults
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options for Linux with our own Linux .cocciconfig. This hints to coccinelle
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git can be used for 'git grep' queries over coccigrep. A timeout of 200
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seconds should suffice for now.
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The options picked up by coccinelle when reading a .cocciconfig do not appear
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as arguments to spatch processes running on your system, to confirm what
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options will be used by Coccinelle run:
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spatch --print-options-only
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You can override with your own preferred index option by using SPFLAGS. Take
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note that when there are conflicting options Coccinelle takes precedence for
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the last options passed. Using .cocciconfig is possible to use idutils, however
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given the order of precedence followed by Coccinelle, since the kernel now
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carries its own .cocciconfig, you will need to use SPFLAGS to use idutils if
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desired. See below section "Additional flags" for more details on how to use
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idutils.
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Additional flags
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~~~~~~~~~~~~~~~~~~
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Additional flags can be passed to spatch through the SPFLAGS
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variable. This works as Coccinelle respects the last flags
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given to it when options are in conflict.
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make SPFLAGS=--use-glimpse coccicheck
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Coccinelle supports idutils as well but requires coccinelle >= 1.0.6.
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When no ID file is specified coccinelle assumes your ID database file
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is in the file .id-utils.index on the top level of the kernel, coccinelle
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carries a script scripts/idutils_index.sh which creates the database with
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mkid -i C --output .id-utils.index
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If you have another database filename you can also just symlink with this
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name.
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make SPFLAGS=--use-idutils coccicheck
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Alternatively you can specify the database filename explicitly, for
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instance:
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make SPFLAGS="--use-idutils /full-path/to/ID" coccicheck
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See spatch --help to learn more about spatch options.
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Note that the '--use-glimpse' and '--use-idutils' options
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require external tools for indexing the code. None of them is
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thus active by default. However, by indexing the code with
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one of these tools, and according to the cocci file used,
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spatch could proceed the entire code base more quickly.
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Proposing new semantic patches
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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New semantic patches can be proposed and submitted by kernel
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developers. For sake of clarity, they should be organized in the
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sub-directories of 'scripts/coccinelle/'.
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Detailed description of the 'report' mode
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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'report' generates a list in the following format:
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file:line:column-column: message
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Example:
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Running
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make coccicheck MODE=report COCCI=scripts/coccinelle/api/err_cast.cocci
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will execute the following part of the SmPL script.
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<smpl>
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@r depends on !context && !patch && (org || report)@
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expression x;
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position p;
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@@
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ERR_PTR@p(PTR_ERR(x))
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@script:python depends on report@
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p << r.p;
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x << r.x;
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@@
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msg="ERR_CAST can be used with %s" % (x)
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coccilib.report.print_report(p[0], msg)
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</smpl>
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This SmPL excerpt generates entries on the standard output, as
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illustrated below:
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/home/user/linux/crypto/ctr.c:188:9-16: ERR_CAST can be used with alg
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/home/user/linux/crypto/authenc.c:619:9-16: ERR_CAST can be used with auth
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/home/user/linux/crypto/xts.c:227:9-16: ERR_CAST can be used with alg
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Detailed description of the 'patch' mode
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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When the 'patch' mode is available, it proposes a fix for each problem
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identified.
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Example:
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Running
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make coccicheck MODE=patch COCCI=scripts/coccinelle/api/err_cast.cocci
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will execute the following part of the SmPL script.
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<smpl>
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@ depends on !context && patch && !org && !report @
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expression x;
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@@
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- ERR_PTR(PTR_ERR(x))
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+ ERR_CAST(x)
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</smpl>
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This SmPL excerpt generates patch hunks on the standard output, as
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illustrated below:
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diff -u -p a/crypto/ctr.c b/crypto/ctr.c
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--- a/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
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+++ b/crypto/ctr.c 2010-06-03 23:44:49.000000000 +0200
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@@ -185,7 +185,7 @@ static struct crypto_instance *crypto_ct
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alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
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CRYPTO_ALG_TYPE_MASK);
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if (IS_ERR(alg))
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- return ERR_PTR(PTR_ERR(alg));
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+ return ERR_CAST(alg);
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/* Block size must be >= 4 bytes. */
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err = -EINVAL;
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Detailed description of the 'context' mode
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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'context' highlights lines of interest and their context
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in a diff-like style.
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NOTE: The diff-like output generated is NOT an applicable patch. The
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intent of the 'context' mode is to highlight the important lines
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(annotated with minus, '-') and gives some surrounding context
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lines around. This output can be used with the diff mode of
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Emacs to review the code.
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Example:
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Running
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make coccicheck MODE=context COCCI=scripts/coccinelle/api/err_cast.cocci
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will execute the following part of the SmPL script.
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<smpl>
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@ depends on context && !patch && !org && !report@
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expression x;
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@@
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* ERR_PTR(PTR_ERR(x))
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</smpl>
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This SmPL excerpt generates diff hunks on the standard output, as
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illustrated below:
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diff -u -p /home/user/linux/crypto/ctr.c /tmp/nothing
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--- /home/user/linux/crypto/ctr.c 2010-05-26 10:49:38.000000000 +0200
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+++ /tmp/nothing
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@@ -185,7 +185,6 @@ static struct crypto_instance *crypto_ct
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alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER,
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CRYPTO_ALG_TYPE_MASK);
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if (IS_ERR(alg))
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- return ERR_PTR(PTR_ERR(alg));
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/* Block size must be >= 4 bytes. */
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err = -EINVAL;
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Detailed description of the 'org' mode
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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'org' generates a report in the Org mode format of Emacs.
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Example:
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Running
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make coccicheck MODE=org COCCI=scripts/coccinelle/api/err_cast.cocci
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will execute the following part of the SmPL script.
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<smpl>
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@r depends on !context && !patch && (org || report)@
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expression x;
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position p;
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@@
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ERR_PTR@p(PTR_ERR(x))
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@script:python depends on org@
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p << r.p;
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x << r.x;
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@@
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msg="ERR_CAST can be used with %s" % (x)
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msg_safe=msg.replace("[","@(").replace("]",")")
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coccilib.org.print_todo(p[0], msg_safe)
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</smpl>
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This SmPL excerpt generates Org entries on the standard output, as
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illustrated below:
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* TODO [[view:/home/user/linux/crypto/ctr.c::face=ovl-face1::linb=188::colb=9::cole=16][ERR_CAST can be used with alg]]
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* TODO [[view:/home/user/linux/crypto/authenc.c::face=ovl-face1::linb=619::colb=9::cole=16][ERR_CAST can be used with auth]]
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* 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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