xref: /openbmc/linux/scripts/gcc-plugins/Kconfig (revision 842ed298)
1# SPDX-License-Identifier: GPL-2.0-only
2config HAVE_GCC_PLUGINS
3	bool
4	help
5	  An arch should select this symbol if it supports building with
6	  GCC plugins.
7
8menuconfig GCC_PLUGINS
9	bool "GCC plugins"
10	depends on HAVE_GCC_PLUGINS
11	depends on CC_IS_GCC
12	depends on $(success,test -e $(shell,$(CC) -print-file-name=plugin)/include/plugin-version.h)
13	default y
14	help
15	  GCC plugins are loadable modules that provide extra features to the
16	  compiler. They are useful for runtime instrumentation and static analysis.
17
18	  See Documentation/kbuild/gcc-plugins.rst for details.
19
20if GCC_PLUGINS
21
22config GCC_PLUGIN_CYC_COMPLEXITY
23	bool "Compute the cyclomatic complexity of a function" if EXPERT
24	depends on !COMPILE_TEST	# too noisy
25	help
26	  The complexity M of a function's control flow graph is defined as:
27	   M = E - N + 2P
28	  where
29
30	  E = the number of edges
31	  N = the number of nodes
32	  P = the number of connected components (exit nodes).
33
34	  Enabling this plugin reports the complexity to stderr during the
35	  build. It mainly serves as a simple example of how to create a
36	  gcc plugin for the kernel.
37
38config GCC_PLUGIN_SANCOV
39	bool
40	help
41	  This plugin inserts a __sanitizer_cov_trace_pc() call at the start of
42	  basic blocks. It supports all gcc versions with plugin support (from
43	  gcc-4.5 on). It is based on the commit "Add fuzzing coverage support"
44	  by Dmitry Vyukov <dvyukov@google.com>.
45
46config GCC_PLUGIN_LATENT_ENTROPY
47	bool "Generate some entropy during boot and runtime"
48	help
49	  By saying Y here the kernel will instrument some kernel code to
50	  extract some entropy from both original and artificially created
51	  program state.  This will help especially embedded systems where
52	  there is little 'natural' source of entropy normally.  The cost
53	  is some slowdown of the boot process (about 0.5%) and fork and
54	  irq processing.
55
56	  Note that entropy extracted this way is not cryptographically
57	  secure!
58
59	  This plugin was ported from grsecurity/PaX. More information at:
60	   * https://grsecurity.net/
61	   * https://pax.grsecurity.net/
62
63config GCC_PLUGIN_RANDSTRUCT
64	bool "Randomize layout of sensitive kernel structures"
65	select MODVERSIONS if MODULES
66	help
67	  If you say Y here, the layouts of structures that are entirely
68	  function pointers (and have not been manually annotated with
69	  __no_randomize_layout), or structures that have been explicitly
70	  marked with __randomize_layout, will be randomized at compile-time.
71	  This can introduce the requirement of an additional information
72	  exposure vulnerability for exploits targeting these structure
73	  types.
74
75	  Enabling this feature will introduce some performance impact,
76	  slightly increase memory usage, and prevent the use of forensic
77	  tools like Volatility against the system (unless the kernel
78	  source tree isn't cleaned after kernel installation).
79
80	  The seed used for compilation is located at
81	  scripts/gcc-plugins/randomize_layout_seed.h.  It remains after
82	  a make clean to allow for external modules to be compiled with
83	  the existing seed and will be removed by a make mrproper or
84	  make distclean.
85
86	  Note that the implementation requires gcc 4.7 or newer.
87
88	  This plugin was ported from grsecurity/PaX. More information at:
89	   * https://grsecurity.net/
90	   * https://pax.grsecurity.net/
91
92config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
93	bool "Use cacheline-aware structure randomization"
94	depends on GCC_PLUGIN_RANDSTRUCT
95	depends on !COMPILE_TEST	# do not reduce test coverage
96	help
97	  If you say Y here, the RANDSTRUCT randomization will make a
98	  best effort at restricting randomization to cacheline-sized
99	  groups of elements.  It will further not randomize bitfields
100	  in structures.  This reduces the performance hit of RANDSTRUCT
101	  at the cost of weakened randomization.
102
103config GCC_PLUGIN_ARM_SSP_PER_TASK
104	bool
105	depends on GCC_PLUGINS && ARM
106
107endif
108