Message-ID: <CAKwvOdkZY5R-pU-Obz0GgwXfL=POqXkkMwidj=C3pip_vxMuog@mail.gmail.com>
Date:   Mon, 29 Aug 2022 12:14:31 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        linuxppc-dev@...ts.ozlabs.org, linux-kbuild@...r.kernel.org,
        Alexey Dobriyan <adobriyan@...il.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Daniel Axtens <dja@...ens.net>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Kees Cook <keescook@...omium.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Nathan Chancellor <nathan@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] powerpc: clean up binutils version check

On Sat, Aug 27, 2022 at 9:43 AM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> The checkbin in arch/powerpc/Makefile errors out if ld <= 2.24.
> So, the requirement on PPC is binutils >= 2.25. It is cleaner to
> specify it in scripts/min-tool-version.sh. If binutils < 2.25 is
> used, the toolchain check will fail in the Kconfig stage going
> forward.

Thoughts on making binutils 2.25.1 the new minimal support version for
all architectures? We already require GCC 5.1. Looking at

https://gcc.gnu.org/releases.html

that was released on April 22, 2015.  Looking at

https://ftp.gnu.org/gnu/binutils/

2.25 was released on 2014-12-23 and 2.25.1 on 2015-07-21.

Current minimum is 2.23 released on 2012-10-22.  Almost 10 years old.

>
> Since binutils >= 2.25 is already required, another version test
> for --save-restore-funcs on PPC64 is always met.
>
> PPC is the last user of ld-ifversion. With all the callers removed,
> the macro definition in scripts/Makefile.compiler can go away.
>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
>
>  arch/powerpc/Makefile       | 21 ---------------------
>  arch/powerpc/lib/Makefile   |  8 --------
>  scripts/Makefile.compiler   |  4 ----
>  scripts/min-tool-version.sh |  8 +++++++-
>  4 files changed, 7 insertions(+), 34 deletions(-)
>
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index 02742facf895..fb607758eeca 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -46,13 +46,7 @@ UTS_MACHINE := $(subst $(space),,$(machine-y))
>  ifdef CONFIG_PPC32
>  KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o
>  else
> -ifeq ($(call ld-ifversion, -ge, 22500, y),y)
> -# Have the linker provide sfpr if possible.
> -# There is a corresponding test in arch/powerpc/lib/Makefile
>  KBUILD_LDFLAGS_MODULE += --save-restore-funcs
> -else
> -KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o
> -endif
>  endif
>
>  ifdef CONFIG_CPU_LITTLE_ENDIAN
> @@ -395,8 +389,6 @@ vdso_prepare: prepare0
>                 $(build)=arch/powerpc/kernel/vdso include/generated/vdso64-offsets.h)
>  endif
>
> -archprepare: checkbin
> -
>  archheaders:
>         $(Q)$(MAKE) $(build)=arch/powerpc/kernel/syscalls all
>
> @@ -411,16 +403,3 @@ else
>         $(eval KBUILD_CFLAGS += -mstack-protector-guard-offset=$(shell awk '{if ($$2 == "TASK_CANARY") print $$3;}' include/generated/asm-offsets.h))
>  endif
>  endif
> -
> -PHONY += checkbin
> -# Check toolchain versions:
> -# - gcc-4.6 is the minimum kernel-wide version so nothing required.
> -checkbin:
> -       @if test "x${CONFIG_LD_IS_LLD}" != "xy" -a \
> -               "x$(call ld-ifversion, -le, 22400, y)" = "xy" ; then \
> -               echo -n '*** binutils 2.24 miscompiles weak symbols ' ; \
> -               echo 'in some circumstances.' ; \
> -               echo    '*** binutils 2.23 do not define the TOC symbol ' ; \
> -               echo -n '*** Please use a different binutils version.' ; \
> -               false ; \
> -       fi
> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
> index 8560c912186d..5eb3971ccb9c 100644
> --- a/arch/powerpc/lib/Makefile
> +++ b/arch/powerpc/lib/Makefile
> @@ -38,14 +38,6 @@ obj-$(CONFIG_PPC32)  += div64.o copy_32.o crtsavres.o
>
>  obj-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
>
> -# See corresponding test in arch/powerpc/Makefile
> -# 64-bit linker creates .sfpr on demand for final link (vmlinux),
> -# so it is only needed for modules, and only for older linkers which
> -# do not support --save-restore-funcs
> -ifeq ($(call ld-ifversion, -lt, 22500, y),y)
> -extra-$(CONFIG_PPC64)  += crtsavres.o
> -endif
> -
>  obj-$(CONFIG_PPC_BOOK3S_64) += copyuser_power7.o copypage_power7.o \
>                                memcpy_power7.o restart_table.o
>
> diff --git a/scripts/Makefile.compiler b/scripts/Makefile.compiler
> index 94d0d40cddb3..63e7d79dd877 100644
> --- a/scripts/Makefile.compiler
> +++ b/scripts/Makefile.compiler
> @@ -68,7 +68,3 @@ cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || e
>  # ld-option
>  # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
>  ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
> -
> -# ld-ifversion
> -# Usage:  $(call ld-ifversion, -ge, 22252, y)
> -ld-ifversion = $(shell [ $(CONFIG_LD_VERSION)0 $(1) $(2)0 ] && echo $(3) || echo $(4))
> diff --git a/scripts/min-tool-version.sh b/scripts/min-tool-version.sh
> index 250925aab101..7df9f2150ea1 100755
> --- a/scripts/min-tool-version.sh
> +++ b/scripts/min-tool-version.sh
> @@ -14,7 +14,13 @@ fi
>
>  case "$1" in
>  binutils)
> -       echo 2.23.0
> +       if [ "$SRCARCH" = powerpc ]; then
> +               # binutils 2.24 miscompiles weak symbols in some circumstances
> +               # binutils 2.23 do not define the TOC symbol
> +               echo 2.25.0
> +       else
> +               echo 2.23.0
> +       fi
>         ;;
>  gcc)
>         echo 5.1.0
> --
> 2.34.1
>


-- 
Thanks,
~Nick Desaulniers

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