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Message-ID: <CAGXu5jJB3AKMC8U--H61eUkFJeMogLMq00dBUUrfg4n2b4FbOQ@mail.gmail.com>
Date: Wed, 28 Mar 2018 04:44:32 -0700
From: Kees Cook <keescook@...omium.org>
To: Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc: linux-kbuild <linux-kbuild@...r.kernel.org>, Sam Ravnborg <sam@...nborg.org>,
Linus Torvalds <torvalds@...ux-foundation.org>, Arnd Bergmann <arnd@...db.de>,
Ulf Magnusson <ulfalizer@...il.com>, Thomas Gleixner <tglx@...utronix.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Randy Dunlap <rdunlap@...radead.org>,
"Luis R . Rodriguez" <mcgrof@...nel.org>, Nicolas Pitre <nico@...aro.org>, LKML <linux-kernel@...r.kernel.org>,
Kernel Hardening <kernel-hardening@...ts.openwall.com>, Emese Revfy <re.emese@...il.com>
Subject: Re: [PATCH v2 19/21] gcc-plugins: test GCC plugin support in Kconfig
On Mon, Mar 26, 2018 at 10:29 PM, Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> Run scripts/gcc-plugin.sh from Kconfig. Users can enable GCC_PLUGINS
> only when it is supported.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
>
> Changes in v2: None
>
> arch/Kconfig | 4 +++
> scripts/Makefile.gcc-plugins | 82 ++++++++++++++++----------------------------
> scripts/gcc-plugin.sh | 1 -
> 3 files changed, 33 insertions(+), 54 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index b42378d..88cc925 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -407,9 +407,13 @@ config HAVE_GCC_PLUGINS
> An arch should select this symbol if it supports building with
> GCC plugins.
>
> +config CC_HAS_GCC_PLUGINS
> + bool
> +
This doesn't seem used anywhere?
> menuconfig GCC_PLUGINS
> bool "GCC plugins"
> depends on HAVE_GCC_PLUGINS
> + depends on $(success $srctree/scripts/gcc-plugin.sh $HOSTCXX $CC)
> depends on !COMPILE_TEST
> help
> GCC plugins are loadable modules that provide extra features to the
> diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins
> index 25da4c0..19d0d5b 100644
> --- a/scripts/Makefile.gcc-plugins
> +++ b/scripts/Makefile.gcc-plugins
> [...]
> -# If plugins aren't supported, abort the build before hard-to-read compiler
> -# errors start getting spewed by the main build.
> -PHONY += gcc-plugins-check
> -gcc-plugins-check: FORCE
> -ifdef CONFIG_GCC_PLUGINS
> - ifeq ($(PLUGINCC),)
> - ifneq ($(GCC_PLUGINS_CFLAGS),)
> - $(Q)$(srctree)/scripts/gcc-plugin.sh --show-error $(HOSTCXX) $(CC) || true
> - @echo "Cannot use CONFIG_GCC_PLUGINS: your gcc installation does not support plugins, perhaps the necessary headers are missing?" >&2 && exit 1
As mentioned in the other email, we lose the error reporting. Now the
lack of plugins is just a silent =n in menuconfig. Keeping
--show-error in the Kconfig call and retaining stderr would be nice.
I need to do some further testing with SANCOV, but otherwise this all
looks correct, and my testing shows it behaving correctly.
-Kees
--
Kees Cook
Pixel Security
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