Re: ld.lld: error: relocation R_RISCV_HI20 cannot be used against symbol 'misaligned_access_speed'; recompile with -fPIC

[Nick Desaulniers]

On Tue, Jun 13, 2023 at 4:17 AM Alexandre Ghiti <alexghiti@xxxxxxxxxxxx> wrote:
>
> On Sun, Jun 11, 2023 at 2:11 AM kernel test robot <lkp@xxxxxxxxx> wrote:
> >
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   022ce8862dff83c859089cd14bc4dca0733e2f90
> > commit: 8dc2a7e8027fbeca0c7df81d4c82e735a59b5741 riscv: Fix relocatable kernels with early alternatives using -fno-pie
> > date:   10 days ago
> > config: riscv-randconfig-r022-20230611 (https://download.01.org/0day-ci/archive/20230611/202306110855.7TlBCIzI-lkp@xxxxxxxxx/config)
> > compiler: clang version 16.0.4 (https://github.com/llvm/llvm-project.git ae42196bc493ffe877a7e3dff8be32035dea4d07)
> > reproduce (this is a W=1 build):
> >         mkdir -p ~/bin
> >         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         # install riscv cross compiling tool for clang build
> >         # apt-get install binutils-riscv64-linux-gnu
> >         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8dc2a7e8027fbeca0c7df81d4c82e735a59b5741
> >         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> >         git fetch --no-tags linus master
> >         git checkout 8dc2a7e8027fbeca0c7df81d4c82e735a59b5741
> >         # save the config file
> >         mkdir build_dir && cp config build_dir/.config
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang ~/bin/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash
> >
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202306110855.7TlBCIzI-lkp@xxxxxxxxx/
> >
> > All errors (new ones prefixed by >>):
> >
> > >> ld.lld: error: relocation R_RISCV_HI20 cannot be used against symbol 'misaligned_access_speed'; recompile with -fPIC
> >    >>> defined in vmlinux.a(arch/riscv/kernel/cpufeature.o)
> >    >>> referenced by errata.c:42 (arch/riscv/errata/thead/errata.c:42)
> >    >>>               arch/riscv/errata/thead/errata.o:(thead_feature_probe_func) in archive vmlinux.a
> > --
> > >> ld.lld: error: relocation R_RISCV_LO12_I cannot be used against symbol 'misaligned_access_speed'; recompile with -fPIC
> >    >>> defined in vmlinux.a(arch/riscv/kernel/cpufeature.o)
> >    >>> referenced by errata.c:42 (arch/riscv/errata/thead/errata.c:42)
> >    >>>               arch/riscv/errata/thead/errata.o:(thead_feature_probe_func) in archive vmlinux.a
> > --
> > >> ld.lld: error: relocation R_RISCV_HI20 cannot be used against symbol 'riscv_cbom_block_size'; recompile with -fPIC
> >    >>> defined in vmlinux.a(arch/riscv/mm/cacheflush.o)
> >    >>> referenced by errata.c:42 (arch/riscv/errata/thead/errata.c:42)
> >    >>>               arch/riscv/errata/thead/errata.o:(thead_errata_patch_func) in archive vmlinux.a
> > --
> > >> ld.lld: error: relocation R_RISCV_LO12_S cannot be used against symbol 'riscv_cbom_block_size'; recompile with -fPIC
> >    >>> defined in vmlinux.a(arch/riscv/mm/cacheflush.o)
> >    >>> referenced by errata.c:42 (arch/riscv/errata/thead/errata.c:42)
> >    >>>               arch/riscv/errata/thead/errata.o:(thead_errata_patch_func) in archive vmlinux.a
> > --
> > >> ld.lld: error: relocation R_RISCV_HI20 cannot be used against symbol '__per_cpu_offset'; recompile with -fPIC
> >    >>> defined in vmlinux.a(mm/percpu.o)
> >    >>> referenced by errata.c:42 (arch/riscv/errata/thead/errata.c:42)
> >    >>>               arch/riscv/errata/thead/errata.o:(thead_feature_probe_func) in archive vmlinux.a
> > --
> > >> ld.lld: error: relocation R_RISCV_LO12_I cannot be used against symbol '__per_cpu_offset'; recompile with -fPIC
> >    >>> defined in vmlinux.a(mm/percpu.o)
> >    >>> referenced by errata.c:42 (arch/riscv/errata/thead/errata.c:42)
> >    >>>               arch/riscv/errata/thead/errata.o:(thead_feature_probe_func) in archive vmlinux.a
> >
>
> So I looked into those errors, the config is basically = RELOCATABLE +
> MEDLOW - EARLY_ALTERNATIVES. Then errata/thead is not compiled as

Thanks for taking a look.  Shouldn't CONFIG_RELOCATABLE be setting
-fPIC? If so, why is LLD complaining about -fPIC not being used?

arch/riscv/Makefile sets -fPIE if CONFIG_RELOCATABLE == y.

Is it possible that -fpie was dropped for these object files, or
-fno-pic or -fno-pie was added to the cflags for these object files
somehow?

I've filed
https://github.com/ClangBuiltLinux/linux/issues/1872
to track this.

> medany, which makes sense since we only need this code to be medany
> when EARLY_ALTERNATIVES is enabled (because the code would be executed
> with mmu off, which is not the case here).
>
> I can fix those errors by adding the medany flag, but I'm not sure
> actually we want to do that since we do not need it and gcc does not
> complain: any idea?
>
> Alex
>
>
>
> > --
> > 0-DAY CI Kernel Test Service
> > https://github.com/intel/lkp-tests/wiki
>


-- 
Thanks,
~Nick Desaulniers