[cryptodev:master 130/134] aes_generic.c:undefined reference to `_restgpr_31_x'

[Arnd Bergmann]

On Fri, Jan 12, 2018 at 3:11 PM, kbuild test robot
<fengguang.wu at intel.com> wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/herbert/cryptodev-2.6.git master
> head:   b40fa82cd6138350f723aa47b37e3e3e80906b40
> commit: 148b974deea927f5dbb6c468af2707b488bfa2de [130/134] crypto: aes-generic - build with -Os on gcc-7+
> config: powerpc-linkstation_defconfig (attached as .config)
> compiler: powerpc-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
> reproduce:
>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
>         chmod +x ~/bin/make.cross
>         git checkout 148b974deea927f5dbb6c468af2707b488bfa2de
>         # save the attached .config to linux build tree
>         make.cross ARCH=powerpc
>
> All errors (new ones prefixed by >>):
>
>    crypto/aes_generic.o: In function `crypto_aes_set_key':
>>> aes_generic.c:(.text+0x4e0): undefined reference to `_restgpr_31_x'

adding linuxpcc-dev to Cc, maybe someone knows a way out of this.
It appears related to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=43810
but I don't know what _restgpr_31_x actually does, why it's not provided
by the kernel or why the aes_generic implementation needs this on
powerpc when built with 'gcc -Os'. FWIW, the -Os change was needed
to work around a possible kernel stack overflow that can happen with
gcc-7.2, see https://patchwork.kernel.org/patch/10143607/ and
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356

         Arnd