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Date: Sun, 7 Feb 2016 22:31:40 +0100
From: Emese Revfy <re.emese@...il.com>
To: linux-kbuild@...r.kernel.org
Cc: pageexec@...email.hu, spender@...ecurity.net,
kernel-hardening@...ts.openwall.com, mmarek@...e.com, keescook@...omium.org
Subject: [PATCH 2/3] Add Cyclomatic complexity GCC plugin
Add a very simple plugin to demonstrate the GCC plugin infrastructure. This GCC
plugin computes the cyclomatic complexity of each function.
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).
---
Makefile | 6 +-
arch/Kconfig | 16 +++++
tools/gcc/Makefile | 4 ++
tools/gcc/cyc_complexity_plugin.c | 120 ++++++++++++++++++++++++++++++++++++++
4 files changed, 145 insertions(+), 1 deletion(-)
create mode 100644 tools/gcc/cyc_complexity_plugin.c
diff --git a/Makefile b/Makefile
index 96ce015..9f76c26 100644
--- a/Makefile
+++ b/Makefile
@@ -628,7 +628,11 @@ else
PLUGINCC := $(shell $(CONFIG_SHELL) $(srctree)/scripts/gcc-plugin.sh "$(HOSTCC)" "$(HOSTCXX)" "$(CC)")
endif
ifneq ($(PLUGINCC),)
-export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS
+ifdef CONFIG_GCC_PLUGIN_CYC_COMPLEXITY
+GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS := -fplugin=$(objtree)/tools/gcc/cyc_complexity_plugin.so -DGCC_PLUGIN_CYC_COMPLEXITY
+endif
+GCC_PLUGINS_CFLAGS := $(GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS)
+export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS GCC_PLUGIN_CYC_COMPLEXITY
ifeq ($(KBUILD_EXTMOD),)
gcc-plugins:
$(Q)$(MAKE) $(build)=tools/gcc
diff --git a/arch/Kconfig b/arch/Kconfig
index a95e5b1..6b7d4de 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -365,6 +365,22 @@ config HAVE_GCC_PLUGINS
An arch should select this symbol if it supports building with
gcc plugins.
+if HAVE_GCC_PLUGINS
+
+config GCC_PLUGIN_CYC_COMPLEXITY
+ bool "Compute the cyclomatic complexity of a function"
+ help
+ The complexity M of a function's control flow graph is defined as:
+ M = E - N + 2P
+ where
+
+ E = the number of edges
+ N = the number of nodes
+ P = the number of connected components (exit nodes).
+
+ See Documentation/gcc-plugins.txt for details.
+
+endif # HAVE_GCC_PLUGINS
endmenu # "GCC plugins"
config HAVE_CC_STACKPROTECTOR
diff --git a/tools/gcc/Makefile b/tools/gcc/Makefile
index b2d64af..31c72bf 100644
--- a/tools/gcc/Makefile
+++ b/tools/gcc/Makefile
@@ -12,4 +12,8 @@ endif
export GCCPLUGINS_DIR HOSTLIBS
+$(HOSTLIBS)-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) := cyc_complexity_plugin.so
+
always := $($(HOSTLIBS)-y)
+
+cyc_complexity_plugin-objs := cyc_complexity_plugin.o
diff --git a/tools/gcc/cyc_complexity_plugin.c b/tools/gcc/cyc_complexity_plugin.c
new file mode 100644
index 0000000..c6f0d58
--- /dev/null
+++ b/tools/gcc/cyc_complexity_plugin.c
@@ -0,0 +1,120 @@
+/*
+ * Copyright 2011-2016 by Emese Revfy <re.emese@...il.com>
+ * Licensed under the GPL v2, or (at your option) v3
+ *
+ * Homepage:
+ * https://github.com/ephox-gcc-plugins/cyclomatic_complexity
+ *
+ * http://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"
+
+int plugin_is_GPL_compatible;
+
+static struct plugin_info cyc_complexity_plugin_info = {
+ .version = "20150523",
+ .help = "Cyclomatic Complexity\n",
+};
+
+static unsigned int handle_function(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;
+}
+
+#if BUILDING_GCC_VERSION >= 4009
+namespace {
+static const struct pass_data cyc_complexity_pass_data = {
+#else
+static struct gimple_opt_pass cyc_complexity_pass = {
+ .pass = {
+#endif
+ .type = GIMPLE_PASS,
+ .name = "cyc_complexity",
+#if BUILDING_GCC_VERSION >= 4008
+ .optinfo_flags = OPTGROUP_NONE,
+#endif
+#if BUILDING_GCC_VERSION >= 5000
+#elif BUILDING_GCC_VERSION >= 4009
+ .has_gate = false,
+ .has_execute = true,
+#else
+ .gate = NULL,
+ .execute = handle_function,
+ .sub = NULL,
+ .next = NULL,
+ .static_pass_number = 0,
+#endif
+ .tv_id = TV_NONE,
+ .properties_required = 0,
+ .properties_provided = 0,
+ .properties_destroyed = 0,
+ .todo_flags_start = 0,
+ .todo_flags_finish = TODO_dump_func
+#if BUILDING_GCC_VERSION < 4009
+ }
+#endif
+};
+
+#if BUILDING_GCC_VERSION >= 4009
+class cyc_complexity_pass : public gimple_opt_pass {
+public:
+ cyc_complexity_pass() : gimple_opt_pass(cyc_complexity_pass_data, g) {}
+#if BUILDING_GCC_VERSION >= 5000
+ virtual unsigned int execute(function *) { return handle_function(); }
+#else
+ unsigned int execute() { return handle_function(); }
+#endif
+};
+}
+
+static struct opt_pass *make_cyc_complexity_pass(void)
+{
+ return new cyc_complexity_pass();
+}
+#else
+static struct opt_pass *make_cyc_complexity_pass(void)
+{
+ return &cyc_complexity_pass.pass;
+}
+#endif
+
+int plugin_init(struct plugin_name_args *plugin_info, struct plugin_gcc_version *version)
+{
+ const char * const plugin_name = plugin_info->base_name;
+ struct register_pass_info cyc_complexity_pass_info;
+
+ cyc_complexity_pass_info.pass = make_cyc_complexity_pass();
+ cyc_complexity_pass_info.reference_pass_name = "ssa";
+ cyc_complexity_pass_info.ref_pass_instance_number = 1;
+ cyc_complexity_pass_info.pos_op = 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;
+}
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