1 =========================
2 GCC plugin infrastructure
3 =========================
9 GCC plugins are loadable modules that provide extra features to the
10 compiler [1]_. They are useful for runtime instrumentation and static analysis.
11 We can analyse, change and add further code during compilation via
12 callbacks [2]_, GIMPLE [3]_, IPA [4]_ and RTL passes [5]_.
14 The GCC plugin infrastructure of the kernel supports building out-of-tree
15 modules, cross-compilation and building in a separate directory.
16 Plugin source files have to be compilable by a C++ compiler.
18 Currently the GCC plugin infrastructure supports only some architectures.
19 Grep "select HAVE_GCC_PLUGINS" to find out which architectures support
22 This infrastructure was ported from grsecurity [6]_ and PaX [7]_.
26 .. [1] https://gcc.gnu.org/onlinedocs/gccint/Plugins.html
27 .. [2] https://gcc.gnu.org/onlinedocs/gccint/Plugin-API.html#Plugin-API
28 .. [3] https://gcc.gnu.org/onlinedocs/gccint/GIMPLE.html
29 .. [4] https://gcc.gnu.org/onlinedocs/gccint/IPA.html
30 .. [5] https://gcc.gnu.org/onlinedocs/gccint/RTL.html
31 .. [6] https://grsecurity.net/
32 .. [7] https://pax.grsecurity.net/
38 **$(src)/scripts/gcc-plugins**
40 This is the directory of the GCC plugins.
42 **$(src)/scripts/gcc-plugins/gcc-common.h**
44 This is a compatibility header for GCC plugins.
45 It should be always included instead of individual gcc headers.
47 **$(src)/scripts/gcc-plugin.sh**
49 This script checks the availability of the included headers in
50 gcc-common.h and chooses the proper host compiler to build the plugins
51 (gcc-4.7 can be built by either gcc or g++).
53 **$(src)/scripts/gcc-plugins/gcc-generate-gimple-pass.h,
54 $(src)/scripts/gcc-plugins/gcc-generate-ipa-pass.h,
55 $(src)/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h,
56 $(src)/scripts/gcc-plugins/gcc-generate-rtl-pass.h**
58 These headers automatically generate the registration structures for
59 GIMPLE, SIMPLE_IPA, IPA and RTL passes.
60 They should be preferred to creating the structures by hand.
66 You must install the gcc plugin headers for your gcc version,
67 e.g., on Ubuntu for gcc-10::
69 apt-get install gcc-10-plugin-dev
73 dnf install gcc-plugin-devel
75 Enable the GCC plugin infrastructure and some plugin(s) you want to use
76 in the kernel config::
79 CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=y
80 CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y
83 To compile the minimum tool set including the plugin(s)::
87 or just run the kernel make and compile the whole kernel with
88 the cyclomatic complexity GCC plugin.
91 4. How to add a new GCC plugin
92 ==============================
94 The GCC plugins are in scripts/gcc-plugins/. You need to put plugin source files
95 right under scripts/gcc-plugins/. Creating subdirectories is not supported.
96 It must be added to scripts/gcc-plugins/Makefile, scripts/Makefile.gcc-plugins
97 and a relevant Kconfig file.
98 See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin.