1 =========================
2 GCC plugin infrastructure
3 =========================
4
5
6 Introduction
7 ============
8
9 GCC plugins are loadable modules that provide
10 compiler [1]_. They are useful for runtime ins
11 We can analyse, change and add further code du
12 callbacks [2]_, GIMPLE [3]_, IPA [4]_ and RTL
13
14 The GCC plugin infrastructure of the kernel su
15 modules, cross-compilation and building in a s
16 Plugin source files have to be compilable by a
17
18 Currently the GCC plugin infrastructure suppor
19 Grep "select HAVE_GCC_PLUGINS" to find out whi
20 GCC plugins.
21
22 This infrastructure was ported from grsecurity
23
24 --
25
26 .. [1] https://gcc.gnu.org/onlinedocs/gccint/P
27 .. [2] https://gcc.gnu.org/onlinedocs/gccint/P
28 .. [3] https://gcc.gnu.org/onlinedocs/gccint/G
29 .. [4] https://gcc.gnu.org/onlinedocs/gccint/I
30 .. [5] https://gcc.gnu.org/onlinedocs/gccint/R
31 .. [6] https://grsecurity.net/
32 .. [7] https://pax.grsecurity.net/
33
34
35 Purpose
36 =======
37
38 GCC plugins are designed to provide a place to
39 compiler features that are neither in GCC nor
40 their utility is proven, the goal is to upstre
41 (and Clang), and then to finally remove them f
42 feature is available in all supported versions
43
44 Specifically, new plugins should implement onl
45 upstream compiler support (in either GCC or Cl
46
47 When a feature exists in Clang but not GCC, ef
48 bring the feature to upstream GCC (rather than
49 GCC plugin), so the entire ecosystem can benef
50
51 Similarly, even if a feature provided by a GCC
52 in Clang, but the feature is proven to be usef
53 to upstream the feature to GCC (and Clang).
54
55 After a feature is available in upstream GCC,
56 unbuildable for the corresponding GCC version
57 kernel-supported versions of GCC provide the f
58 be removed from the kernel.
59
60
61 Files
62 =====
63
64 **$(src)/scripts/gcc-plugins**
65
66 This is the directory of the GCC plugi
67
68 **$(src)/scripts/gcc-plugins/gcc-common.h**
69
70 This is a compatibility header for GCC
71 It should be always included instead o
72
73 **$(src)/scripts/gcc-plugins/gcc-generate-gimp
74 $(src)/scripts/gcc-plugins/gcc-generate-ipa-pa
75 $(src)/scripts/gcc-plugins/gcc-generate-simple
76 $(src)/scripts/gcc-plugins/gcc-generate-rtl-pa
77
78 These headers automatically generate t
79 GIMPLE, SIMPLE_IPA, IPA and RTL passes
80 They should be preferred to creating t
81
82
83 Usage
84 =====
85
86 You must install the gcc plugin headers for yo
87 e.g., on Ubuntu for gcc-10::
88
89 apt-get install gcc-10-plugin-dev
90
91 Or on Fedora::
92
93 dnf install gcc-plugin-devel libmpc-de
94
95 Or on Fedora when using cross-compilers that i
96
97 dnf install libmpc-devel
98
99 Enable the GCC plugin infrastructure and some
100 in the kernel config::
101
102 CONFIG_GCC_PLUGINS=y
103 CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y
104 ...
105
106 Run gcc (native or cross-compiler) to ensure p
107
108 gcc -print-file-name=plugin
109 CROSS_COMPILE=arm-linux-gnu- ${CROSS_C
110
111 The word "plugin" means they are not detected:
112
113 plugin
114
115 A full path means they are detected::
116
117 /usr/lib/gcc/x86_64-redhat-linux/12/plu
118
119 To compile the minimum tool set including the
120
121 make scripts
122
123 or just run the kernel make and compile the wh
124 the cyclomatic complexity GCC plugin.
125
126
127 4. How to add a new GCC plugin
128 ==============================
129
130 The GCC plugins are in scripts/gcc-plugins/. Y
131 right under scripts/gcc-plugins/. Creating sub
132 It must be added to scripts/gcc-plugins/Makefi
133 and a relevant Kconfig file.
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