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gcc-plugins: Remove cyc_complexity

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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: Kees Cook <keescook@chromium.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20211020173554.38122-3-keescook@chromium.org
This commit is contained in:
Kees Cook 2021-10-20 10:35:54 -07:00
parent 8bd51a2ba3
commit b4d89579cc
4 changed files with 0 additions and 89 deletions
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2
Documentation/kbuild/gcc-plugins.rst
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@ -96,7 +96,6 @@ Enable the GCC plugin infrastructure and some plugin(s) you want to use
in the kernel config:: in the kernel config::
CONFIG_GCC_PLUGINS=y CONFIG_GCC_PLUGINS=y
CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=y
CONFIG_GCC_PLUGIN_LATENT_ENTROPY=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. right under scripts/gcc-plugins/. Creating subdirectories is not supported.
It must be added to scripts/gcc-plugins/Makefile, scripts/Makefile.gcc-plugins It must be added to scripts/gcc-plugins/Makefile, scripts/Makefile.gcc-plugins
and a relevant Kconfig file. and a relevant Kconfig file.
See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin.

2
scripts/Makefile.gcc-plugins
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@ -1,7 +1,5 @@
# SPDX-License-Identifier: GPL-2.0 # 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-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += latent_entropy_plugin.so
gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) \ gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) \
+= -DLATENT_ENTROPY_PLUGIN += -DLATENT_ENTROPY_PLUGIN

16
scripts/gcc-plugins/Kconfig
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@ -19,22 +19,6 @@ menuconfig GCC_PLUGINS
if 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 config GCC_PLUGIN_SANCOV
bool bool
# Plugin can be removed once the kernel only supports GCC 6+ # Plugin can be removed once the kernel only supports GCC 6+

69
scripts/gcc-plugins/cyc_complexity_plugin.c
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@ -1,69 +0,0 @@
/*
* 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;
}