[Buildroot] [PATCH next] tpm2-abrmd: fix build without stack smashing protection (SSP)

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

On Wed, 21 Nov 2018 15:43:37 -0200, Carlos Santos wrote:
> The configuration environment setup that disables SSP if the toolchain
> does not support it must be updated after the bump to version 2.0.3.
> 
> Fixes:
>   http://autobuild.buildroot.net/results/bd9005eeb24678aa530179a80bbc99b2176f8559
>   http://autobuild.buildroot.net/results/feff61dcb481a94f5f030117830984c5e09727ea
> 
> Signed-off-by: Carlos Santos <casantos@datacom.com.br>
> ---
>  package/tpm2-abrmd/tpm2-abrmd.mk | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/package/tpm2-abrmd/tpm2-abrmd.mk b/package/tpm2-abrmd/tpm2-abrmd.mk
> index a4d9cfb384..74cc66ba20 100644
> --- a/package/tpm2-abrmd/tpm2-abrmd.mk
> +++ b/package/tpm2-abrmd/tpm2-abrmd.mk
> @@ -13,7 +13,7 @@ TPM2_ABRMD_DEPENDENCIES = dbus libglib2 tpm2-tss host-pkgconf
>  
>  # configure.ac doesn't contain a link test, so it doesn't detect when
>  # libssp is missing.
> -TPM2_ABRMD_CONF_ENV = ax_cv_check_cflags___fstack_protector_all=$(if $(BR2_TOOLCHAIN_HAS_SSP),yes,no)
> +TPM2_ABRMD_CONF_ENV = ax_cv_check_cflags___________Werror_______fstack_protector_all=$(if $(BR2_TOOLCHAIN_HAS_SSP),yes,no)

It's a bit annoying to fix this once in a while, what about the
following change instead:

diff --git a/m4/flags.m4 b/m4/flags.m4
index 1b01198..59b6d5b 100644
--- a/m4/flags.m4
+++ b/m4/flags.m4
@@ -5,7 +5,7 @@ dnl   mandatory (configure will fail).
 dnl $1: C compiler flag to add to EXTRA_CFLAGS.
 dnl $2: Set to "required" to cause configure failure if flag not supported..
 AC_DEFUN([AX_ADD_COMPILER_FLAG],[
-    AX_CHECK_COMPILE_FLAG([$1],[
+    AX_CHECK_LINK_FLAG([$1],[
         EXTRA_CFLAGS="$EXTRA_CFLAGS $1"
         AC_SUBST([EXTRA_CFLAGS])],[
         AS_IF([test x$2 != xrequired],[

(entirely untested). It could be submitted upstream.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com