[kernel-hardening] Re: [PATCH v5 3/5] Add Cyclomatic complexity GCC plugin

Masahiro Yamada
2016-03-11T06:26:39Z

Hi Emese,

2016-03-07 8:05 GMT+09:00 Emese Revfy <re.emese@gmail.com>:
> 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).
>
> Signed-off-by: Emese Revfy <re.emese@gmail.com>
> ---
> arch/Kconfig | 12 +++++++
> scripts/Makefile.gcc-plugins | 6 +++-
> tools/gcc/Makefile | 4 +++
> tools/gcc/cyc_complexity_plugin.c | 73 +++++++++++++++++++++++++++++++++++++++
> 4 files changed, 94 insertions(+), 1 deletion(-)
> create mode 100644 tools/gcc/cyc_complexity_plugin.c
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index e090642..59bde9b 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -370,6 +370,18 @@ menuconfig GCC_PLUGINS
> GCC plugins are loadable modules that provide extra features to the
> compiler. They are useful for runtime instrumentation and static analysis.
>
> +config GCC_PLUGIN_CYC_COMPLEXITY
> + bool "Compute the cyclomatic complexity of a function"
> + depends on GCC_PLUGINS
> + 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).
> +
> config HAVE_CC_STACKPROTECTOR
> bool
> help
> diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
> index 7c85bf2..dd7b56d 100644
> --- a/scripts/Makefile.gcc-plugins
> +++ b/scripts/Makefile.gcc-plugins
> @@ -5,7 +5,11 @@ 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
> +endif
> +GCC_PLUGINS_CFLAGS := $(GCC_PLUGIN_CYC_COMPLEXITY_CFLAGS)
> +export PLUGINCC GCC_PLUGINS_CFLAGS GCC_PLUGINS_AFLAGS GCC_PLUGIN_CYC_COMPLEXITY

Do you need to export "GCC_PLUGIN_CYC_COMPLEXITY"?
I do not see any reference to it.

If we expect more and more plugins in the future,
is it better to do like this?

gcc-plugin-$(CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) += cyc_complexity_plugin.so
gcc-plugin-$(CONFIG_GCC_PLUGIN_SANCOV) += sancov_plugin.so
gcc-plugin-$(CONFIG_GCC_PLUGIN_FOO) += foo_plugin.so

GCC_PLUGINS_CFLAGS := $(addprefix -fplugin=$(objtree)/tools/gcc/,
$(gcc-plugin-y))

--
Best Regards
Masahiro Yamada