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Diffstat (limited to 'Documentation/coccinelle.txt')
| -rw-r--r-- | Documentation/coccinelle.txt | 148 |
1 files changed, 147 insertions, 1 deletions
diff --git a/Documentation/coccinelle.txt b/Documentation/coccinelle.txt index 7f773d51f..01fb1dae3 100644 --- a/Documentation/coccinelle.txt +++ b/Documentation/coccinelle.txt @@ -38,6 +38,15 @@ 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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -94,11 +103,26 @@ 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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -142,15 +166,118 @@ 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: + + 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. 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. +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 @@ -159,6 +286,25 @@ 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 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ |