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Based on kernel version 4.16.1. Page generated on 2018-04-09 11:53 EST.

1	=========================
2	GCC plugin infrastructure
3	=========================
4	
5	
6	Introduction
7	============
8	
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]_.
13	
14	The GCC plugin infrastructure of the kernel supports all gcc versions from
15	4.5 to 6.0, building out-of-tree modules, cross-compilation and building in a
16	separate directory.
17	Plugin source files have to be compilable by both a C and a C++ compiler as well
18	because gcc versions 4.5 and 4.6 are compiled by a C compiler,
19	gcc-4.7 can be compiled by a C or a C++ compiler,
20	and versions 4.8+ can only be compiled by a C++ compiler.
21	
22	Currently the GCC plugin infrastructure supports only the x86, arm, arm64 and
23	powerpc architectures.
24	
25	This infrastructure was ported from grsecurity [6]_ and PaX [7]_.
26	
27	--
28	
29	.. [1] https://gcc.gnu.org/onlinedocs/gccint/Plugins.html
30	.. [2] https://gcc.gnu.org/onlinedocs/gccint/Plugin-API.html#Plugin-API
31	.. [3] https://gcc.gnu.org/onlinedocs/gccint/GIMPLE.html
32	.. [4] https://gcc.gnu.org/onlinedocs/gccint/IPA.html
33	.. [5] https://gcc.gnu.org/onlinedocs/gccint/RTL.html
34	.. [6] https://grsecurity.net/
35	.. [7] https://pax.grsecurity.net/
36	
37	
38	Files
39	=====
40	
41	**$(src)/scripts/gcc-plugins**
42	
43		This is the directory of the GCC plugins.
44	
45	**$(src)/scripts/gcc-plugins/gcc-common.h**
46	
47		This is a compatibility header for GCC plugins.
48		It should be always included instead of individual gcc headers.
49	
50	**$(src)/scripts/gcc-plugin.sh**
51	
52		This script checks the availability of the included headers in
53		gcc-common.h and chooses the proper host compiler to build the plugins
54		(gcc-4.7 can be built by either gcc or g++).
55	
56	**$(src)/scripts/gcc-plugins/gcc-generate-gimple-pass.h,
57	$(src)/scripts/gcc-plugins/gcc-generate-ipa-pass.h,
58	$(src)/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h,
59	$(src)/scripts/gcc-plugins/gcc-generate-rtl-pass.h**
60	
61		These headers automatically generate the registration structures for
62		GIMPLE, SIMPLE_IPA, IPA and RTL passes. They support all gcc versions
63		from 4.5 to 6.0.
64		They should be preferred to creating the structures by hand.
65	
66	
67	Usage
68	=====
69	
70	You must install the gcc plugin headers for your gcc version,
71	e.g., on Ubuntu for gcc-4.9::
72	
73		apt-get install gcc-4.9-plugin-dev
74	
75	Enable a GCC plugin based feature in the kernel config::
76	
77		CONFIG_GCC_PLUGIN_CYC_COMPLEXITY = y
78	
79	To compile only the plugin(s)::
80	
81		make gcc-plugins
82	
83	or just run the kernel make and compile the whole kernel with
84	the cyclomatic complexity GCC plugin.
85	
86	
87	4. How to add a new GCC plugin
88	==============================
89	
90	The GCC plugins are in $(src)/scripts/gcc-plugins/. You can use a file or a directory
91	here. It must be added to $(src)/scripts/gcc-plugins/Makefile,
92	$(src)/scripts/Makefile.gcc-plugins and $(src)/arch/Kconfig.
93	See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin.
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