[PATCH v2 3/7] powerpc/build: move got, toc, plt, branch_lt sections to read-only

[Nicholas Piggin]

On Mon Sep 19, 2022 at 3:39 PM AEST, Michael Ellerman wrote:
> kernel test robot <lkp at intel.com> writes:
> > Hi Nicholas,
> >
> > I love your patch! Yet something to improve:
> >
> > [auto build test ERROR on powerpc/next]
> > [also build test ERROR on linus/master v6.0-rc5 next-20220916]
> > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > And when submitting patch, we suggest to use '--base' as documented in
> > https://git-scm.com/docs/git-format-patch#_base_tree_information]
> >
> > url:    https://github.com/intel-lab-lkp/linux/commits/Nicholas-Piggin/powerpc-build-linker-improvements/20220916-121310
> > base:   https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git next
> > config: powerpc-microwatt_defconfig (https://download.01.org/0day-ci/archive/20220918/202209180437.4U3soljK-lkp@intel.com/config)
> > compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 791a7ae1ba3efd6bca96338e10ffde557ba83920)
> > reproduce (this is a W=1 build):
> >         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         # install powerpc cross compiling tool for clang build
> >         # apt-get install binutils-powerpc-linux-gnu
> >         # https://github.com/intel-lab-lkp/linux/commit/6c034c08f8d0addb6fecba38c9c428b1c4df7c29
> >         git remote add linux-review https://github.com/intel-lab-lkp/linux
> >         git fetch --no-tags linux-review Nicholas-Piggin/powerpc-build-linker-improvements/20220916-121310
> >         git checkout 6c034c08f8d0addb6fecba38c9c428b1c4df7c29
> >         # save the config file
> >         mkdir build_dir && cp config build_dir/.config
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash
>                                                     ^^^^^
>
> > If you fix the issue, kindly add following tag where applicable
> > Reported-by: kernel test robot <lkp at intel.com>
> >
> > All errors (new ones prefixed by >>):
> >
> >>> ld.lld: error: ./arch/powerpc/kernel/vmlinux.lds:46: { expected, but got SPECIAL
> >    >>>  .got : AT(ADDR(.got) - (0xc0000000 -0x00000000)) SPECIAL {
> >    >>>                                                   ^
>
> I guess SPECIAL is a binutils ld ism?
>
> I can't find it documented anywhere.
>
> Presumably we can just not use it, given we never did before?

Yeah that's what it is, oops I just took it from the linker script.

I think we can drop it, I think it selects either old or new plt
sections that are created with --secure-plt, I guess depending on
some link options and copmatibility concerns. Doesn't look like
ppc32 uses --secure-plt.

Thanks,
Nick