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Date: Tue, 12 Mar 2024 14:53:46 -0700
From: Kees Cook <keescook@chromium.org>
To: Thomas =?iso-8859-1?Q?Wei=DFschuh?= <thomas.weissschuh@linutronix.de>
Cc: Masahiro Yamada <masahiroy@kernel.org>, linux-hardening@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org
Subject: Re: [PATCH 2/2] gcc-plugins: disable plugins when gmp.h is
 unavailable
Message-ID: <202403121452.701C91AF6E@keescook>
References: <20240312-gcc-plugins-gmp-v1-0-c5e082437b9e@linutronix.de>
 <20240312-gcc-plugins-gmp-v1-2-c5e082437b9e@linutronix.de>
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In-Reply-To: <20240312-gcc-plugins-gmp-v1-2-c5e082437b9e@linutronix.de>

On Tue, Mar 12, 2024 at 04:03:30PM +0100, Thomas Wei?schuh wrote:
> The header gmp.h is meant to be picked up from the host system.
> 
> When it is unavailable the plugin build fails:
> 
> In file included from ../crosstools/gcc-13.2.0-nolibc/i386-linux/bin/../lib/gcc/i386-linux/13.2.0/plugin/include/gcc-plugin.h:28,
>                  from ../scripts/gcc-plugins/gcc-common.h:7,
>                  from ../scripts/gcc-plugins/stackleak_plugin.c:30:
> ../crosstools/gcc-13.2.0-nolibc/i386-linux/bin/../lib/gcc/i386-linux/13.2.0/plugin/include/system.h:703:10: fatal error: gmp.h: No such file or directory
>   703 | #include <gmp.h>
>       |          ^~~~~~~
> 
> Signed-off-by: Thomas Wei?schuh <thomas.weissschuh@linutronix.de>
> ---
>  scripts/gcc-plugins/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/scripts/gcc-plugins/Kconfig b/scripts/gcc-plugins/Kconfig
> index e383cda05367..a664fb5cdde5 100644
> --- a/scripts/gcc-plugins/Kconfig
> +++ b/scripts/gcc-plugins/Kconfig
> @@ -10,6 +10,7 @@ menuconfig GCC_PLUGINS
>  	depends on HAVE_GCC_PLUGINS
>  	depends on CC_IS_GCC
>  	depends on $(success,test -e $(shell,$(CC) -print-file-name=plugin)/include/plugin-version.h)
> +	depends on $(host-cc-option,-include gmp.h)

Why does the prior depends not fail? That's where plugin detection is
happening.

-- 
Kees Cook