Commit b4d89579 authored by Kees Cook's avatar Kees Cook
Browse files

gcc-plugins: Remove cyc_complexity 



This plugin has no impact on the resulting binary, is disabled
under COMPILE_TEST, and is not enabled on any builds I'm aware of.
Additionally, given the clarified purpose of GCC plugins in the kernel,
remove cyc_complexity.

Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-hardening@vger.kernel.org
Cc: linux-kbuild@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarMiguel Ojeda <ojeda@kernel.org>
Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
Acked-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Acked-by: default avatarArd Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20211020173554.38122-3-keescook@chromium.org
parent 8bd51a2b

Documentation/kbuild/gcc-plugins.rst

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Original line number Diff line number Diff line
@@ -96,7 +96,6 @@ Enable the GCC plugin infrastructure and some plugin(s) you want to use 
in the kernel config::



	CONFIG_GCC_PLUGINS=y

	CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=y

	CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y

	...
@@ -115,4 +114,3 @@ The GCC plugins are in scripts/gcc-plugins/. You need to put plugin source files 
right under scripts/gcc-plugins/. Creating subdirectories is not supported.

It must be added to scripts/gcc-plugins/Makefile, scripts/Makefile.gcc-plugins

and a relevant Kconfig file.
 
See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin.

scripts/Makefile.gcc-plugins

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Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0



gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY)	+= cyc_complexity_plugin.so



gcc-plugin-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY)	+= latent_entropy_plugin.so

gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY)		\

		+= -DLATENT_ENTROPY_PLUGIN

scripts/gcc-plugins/Kconfig

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@@ -19,22 +19,6 @@ menuconfig GCC_PLUGINS 


if GCC_PLUGINS



config GCC_PLUGIN_CYC_COMPLEXITY

	bool "Compute the cyclomatic complexity of a function" if EXPERT

	depends on !COMPILE_TEST	# too noisy

	help

	  The complexity M of a function's control flow graph is defined as:

	   M = E - N + 2P

	  where



	  E = the number of edges

	  N = the number of nodes

	  P = the number of connected components (exit nodes).



	  Enabling this plugin reports the complexity to stderr during the

	  build. It mainly serves as a simple example of how to create a

	  gcc plugin for the kernel.



config GCC_PLUGIN_SANCOV

	bool

	# Plugin can be removed once the kernel only supports GCC 6+

scripts/gcc-plugins/cyc_complexity_plugin.c

deleted100644 → 0
+0 −69
Original line number Diff line number Diff line 
/*

 * Copyright 2011-2016 by Emese Revfy <re.emese@gmail.com>

 * Licensed under the GPL v2, or (at your option) v3

 *

 * Homepage:

 * https://github.com/ephox-gcc-plugins/cyclomatic_complexity

 *

 * https://en.wikipedia.org/wiki/Cyclomatic_complexity

 * The complexity M is then defined as:

 * M = E - N + 2P

 * where

 *

 *  E = the number of edges of the graph

 *  N = the number of nodes of the graph

 *  P = the number of connected components (exit nodes).

 *

 * Usage (4.5 - 5):

 * $ make clean; make run

 */



#include "gcc-common.h"



__visible int plugin_is_GPL_compatible;



static struct plugin_info cyc_complexity_plugin_info = {

	.version	= "20160225",

	.help		= "Cyclomatic Complexity\n",

};



static unsigned int cyc_complexity_execute(void)

{

	int complexity;

	expanded_location xloc;



	/* M = E - N + 2P */

	complexity = n_edges_for_fn(cfun) - n_basic_blocks_for_fn(cfun) + 2;



	xloc = expand_location(DECL_SOURCE_LOCATION(current_function_decl));

	fprintf(stderr, "Cyclomatic Complexity %d %s:%s\n", complexity,

		xloc.file, DECL_NAME_POINTER(current_function_decl));



	return 0;

}



#define PASS_NAME cyc_complexity



#define NO_GATE

#define TODO_FLAGS_FINISH TODO_dump_func



#include "gcc-generate-gimple-pass.h"



__visible int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)

{

	const char * const plugin_name = plugin_info->base_name;



	PASS_INFO(cyc_complexity, "ssa", 1, PASS_POS_INSERT_AFTER);



	if (!plugin_default_version_check(version, &gcc_version)) {

		error(G_("incompatible gcc/plugin versions"));

		return 1;

	}



	register_callback(plugin_name, PLUGIN_INFO, NULL,

				&cyc_complexity_plugin_info);

	register_callback(plugin_name, PLUGIN_PASS_MANAGER_SETUP, NULL,

				&cyc_complexity_pass_info);



	return 0;

}