From 6b90bd4ba40b38dc13c2782469c1c77e4ed79915 Mon Sep 17 00:00:00 2001 From: Emese Revfy Date: Tue, 24 May 2016 00:09:38 +0200 Subject: GCC plugin infrastructure This patch allows to build the whole kernel with GCC plugins. It was ported from grsecurity/PaX. The infrastructure supports building out-of-tree modules and building in a separate directory. Cross-compilation is supported too. Currently the x86, arm, arm64 and uml architectures enable plugins. The directory of the gcc plugins is scripts/gcc-plugins. You can use a file or a directory there. The plugins compile with these options: * -fno-rtti: gcc is compiled with this option so the plugins must use it too * -fno-exceptions: this is inherited from gcc too * -fasynchronous-unwind-tables: this is inherited from gcc too * -ggdb: it is useful for debugging a plugin (better backtrace on internal errors) * -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h) * -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version variable, plugin-version.h) The infrastructure introduces a new Makefile target called gcc-plugins. It supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++). This script also checks the availability of the included headers in scripts/gcc-plugins/gcc-common.h. The gcc-common.h header contains frequently included headers for GCC plugins and it has a compatibility layer for the supported gcc versions. The gcc-generate-*-pass.h headers automatically generate the registration structures for GIMPLE, SIMPLE_IPA, IPA and RTL passes. Note that 'make clean' keeps the *.so files (only the distclean or mrproper targets clean all) because they are needed for out-of-tree modules. Based on work created by the PaX Team. Signed-off-by: Emese Revfy Acked-by: Kees Cook Signed-off-by: Michal Marek --- Documentation/gcc-plugins.txt | 87 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 Documentation/gcc-plugins.txt (limited to 'Documentation/gcc-plugins.txt') diff --git a/Documentation/gcc-plugins.txt b/Documentation/gcc-plugins.txt new file mode 100644 index 000000000000..891c69464434 --- /dev/null +++ b/Documentation/gcc-plugins.txt @@ -0,0 +1,87 @@ +GCC plugin infrastructure +========================= + + +1. Introduction +=============== + +GCC plugins are loadable modules that provide extra features to the +compiler [1]. They are useful for runtime instrumentation and static analysis. +We can analyse, change and add further code during compilation via +callbacks [2], GIMPLE [3], IPA [4] and RTL passes [5]. + +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. +Plugin source files have to be compilable by both a C and a C++ compiler as well +because gcc versions 4.5 and 4.6 are compiled by a C compiler, +gcc-4.7 can be compiled by a C or a C++ compiler, +and versions 4.8+ can only be compiled by a C++ compiler. + +Currently the GCC plugin infrastructure supports only the x86, arm and arm64 +architectures. + +This infrastructure was ported from grsecurity [6] and PaX [7]. + +-- +[1] https://gcc.gnu.org/onlinedocs/gccint/Plugins.html +[2] https://gcc.gnu.org/onlinedocs/gccint/Plugin-API.html#Plugin-API +[3] https://gcc.gnu.org/onlinedocs/gccint/GIMPLE.html +[4] https://gcc.gnu.org/onlinedocs/gccint/IPA.html +[5] https://gcc.gnu.org/onlinedocs/gccint/RTL.html +[6] https://grsecurity.net/ +[7] https://pax.grsecurity.net/ + + +2. Files +======== + +$(src)/scripts/gcc-plugins + This is the directory of the GCC plugins. + +$(src)/scripts/gcc-plugins/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)/scripts/gcc-plugins/gcc-generate-gimple-pass.h +$(src)/scripts/gcc-plugins/gcc-generate-ipa-pass.h +$(src)/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h +$(src)/scripts/gcc-plugins/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)/scripts/gcc-plugins/. You can use a file or a directory +here. It must be added to $(src)/scripts/gcc-plugins/Makefile, +$(src)/scripts/Makefile.gcc-plugins and $(src)/arch/Kconfig. +See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin. -- cgit v1.2.3