linux-kernel - Re: [PATCH v2 20/21] gcc-plugins: enable GCC_PLUGINS for COMPILE

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Message-ID: <CAGXu5jJQfYXqsF7pcRsUtY9Mrw+Yi_Y6+CBAwDrQT_4kpUiHDA@mail.gmail.com>
Date:   Wed, 28 Mar 2018 04:47:50 -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>
Subject: Re: [PATCH v2 20/21] gcc-plugins: enable GCC_PLUGINS for COMPILE_TEST

On Mon, Mar 26, 2018 at 10:29 PM, Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> The plugin availability is checked in Kconfig, so all{yes,mod}config
> will not be bothered.  Remove 'depends on !COMPILE_TEST'.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
> ---
>
> Changes in v2:
>   - Remove more 'depends on'
>
>  arch/Kconfig | 4 ----
>  1 file changed, 4 deletions(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 88cc925..b07094c 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -414,7 +414,6 @@ 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
>           compiler. They are useful for runtime instrumentation and static analysis.

This one is nice, yes! We get coverage for anyone with plugin support.

> @@ -424,7 +423,6 @@ menuconfig GCC_PLUGINS
>  config GCC_PLUGIN_CYC_COMPLEXITY
>         bool "Compute the cyclomatic complexity of a function" if EXPERT
>         depends on GCC_PLUGINS
> -       depends on !COMPILE_TEST
>         help
>           The complexity M of a function's control flow graph is defined as:
>            M = E - N + 2P
> @@ -487,7 +485,6 @@ config GCC_PLUGIN_STRUCTLEAK_BYREF_ALL
>  config GCC_PLUGIN_STRUCTLEAK_VERBOSE
>         bool "Report forcefully initialized variables"
>         depends on GCC_PLUGIN_STRUCTLEAK
> -       depends on !COMPILE_TEST
>         help
>           This option will cause a warning to be printed each time the
>           structleak plugin finds a variable it thinks needs to be
> @@ -527,7 +524,6 @@ config GCC_PLUGIN_RANDSTRUCT
>  config GCC_PLUGIN_RANDSTRUCT_PERFORMANCE
>         bool "Use cacheline-aware structure randomization"
>         depends on GCC_PLUGIN_RANDSTRUCT
> -       depends on !COMPILE_TEST
>         help
>           If you say Y here, the RANDSTRUCT randomization will make a
>           best effort at restricting randomization to cacheline-sized

All three of these, though, please leave as they were. They're either
needlessly noisy for COMPILE_TEST (GCC_PLUGIN_CYC_COMPLEXITY and
*_VERBOSE), or reduce the COMPILE_TEST coverage
(GCC_PLUGIN_RANDSTRUCT_PERFORMANCE).

(And perhaps a comment is needed to explain these to avoid confusion
in the future?)

-Kees

-- 
Kees Cook
Pixel Security