Date: Tue, 1 Mar 2016 18:17:30 +0100 From: Emese Revfy <re.emese@...il.com> To: linux-kbuild@...r.kernel.org Cc: pageexec@...email.hu, spender@...ecurity.net, kernel-hardening@...ts.openwall.com, mmarek@...e.com, keescook@...omium.org, linux@...musvillemoes.dk, fengguang.wu@...el.com Subject: [PATCH v4 3/3] Documentation for the GCC plugin infrastructure This is the GCC infrastructure documentation about its operation, how to add and use a new plugin with an example. Signed-off-by: Emese Revfy <re.emese@...il.com> --- Documentation/gcc-plugins.txt | 82 +++++++++++++++++++++++++++++++++++++++++++ arch/Kconfig | 2 ++ 2 files changed, 84 insertions(+) create mode 100644 Documentation/gcc-plugins.txt diff --git a/Documentation/gcc-plugins.txt b/Documentation/gcc-plugins.txt new file mode 100644 index 0000000..ffb56a3 --- /dev/null +++ b/Documentation/gcc-plugins.txt @@ -0,0 +1,82 @@ +GCC plugin infrastructure +========================= + + +1. Introduction +=============== + +GCC plugins are loadable modules that provide extra features to the +compiler . They are useful for runtime instrumentation and static analysis. +We can analyse, change and add further code during compilation via +callbacks , GIMPLE , IPA  and RTL passes . + +The GCC plugin infrastructure of the kernel supports all gcc versions from +4.5 to 6.0, building out-of-tree modules, cross-compilation and building in a +separate directory. + +Currently the GCC plugin infrastructure supports only the x86 architecture. + +This infrastructure was ported from grsecurity  and PaX . + +-- + https://gcc.gnu.org/onlinedocs/gccint/Plugins.html + https://gcc.gnu.org/onlinedocs/gccint/Plugin-API.html#Plugin-API + https://gcc.gnu.org/onlinedocs/gccint/GIMPLE.html + https://gcc.gnu.org/onlinedocs/gccint/IPA.html + https://gcc.gnu.org/onlinedocs/gccint/RTL.html + https://grsecurity.net/ + https://pax.grsecurity.net/ + + +2. Files +======== + +$(src)/tools/gcc + This is the directory of the GCC plugins. + +$(src)/tools/gcc/gcc-common.h + This is a compatibility header for GCC plugins. + It should be always included instead of individual gcc headers. + +$(src)/scripts/gcc-plugin.sh + This script checks the availability of the included headers in + gcc-common.h and chooses the proper host compiler to build the plugins + (gcc-4.7 can be built by either gcc or g++). + +$(src)/tools/gcc/gcc-generate-gimple-pass.h +$(src)/tools/gcc/gcc-generate-ipa-pass.h +$(src)/tools/gcc/gcc-generate-simple_ipa-pass.h +$(src)/tools/gcc/gcc-generate-rtl-pass.h + These headers automatically generate the registration structures for + GIMPLE, SIMPLE_IPA, IPA and RTL passes. They support all gcc versions + from 4.5 to 6.0. + They should be preferred to creating the structures by hand. + + +3. Usage +======== + +You must install the gcc plugin headers for your gcc version, +e.g., on Ubuntu for gcc-4.9: + + apt-get install gcc-4.9-plugin-dev + +Enable a GCC plugin based feature in the kernel config: + + CONFIG_GCC_PLUGIN_CYC_COMPLEXITY = y + +To compile only the plugin(s): + + make gcc-plugins + +or just run the kernel make and compile the whole kernel with +the cyclomatic complexity GCC plugin. + + +4. How to add a new GCC plugin +============================== + +The GCC plugins are in $(src)/tools/gcc/. You can use a file or a directory +here. It must be added to $(src)/tools/gcc/Makefile, +$(src)/scripts/Makefile.gcc-plugins and $(src)/arch/Kconfig. +See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin. diff --git a/arch/Kconfig b/arch/Kconfig index fa158b2..dc901d3 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -370,6 +370,8 @@ menuconfig GCC_PLUGINS GCC plugins are loadable modules that provide extra features to the compiler. They are useful for runtime instrumentation and static analysis. + See Documentation/gcc-plugins.txt for details. + config GCC_PLUGIN_CYC_COMPLEXITY bool "Compute the cyclomatic complexity of a function" depends on GCC_PLUGINS -- 2.4.1
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