linux-kernel - Re: [PATCH] powerpc: clean up binutils version check

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Message-ID: <58a90319-668f-7c87-4168-e0df10644aa7@csgroup.eu>
Date:   Sat, 27 Aug 2022 17:37:39 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Masahiro Yamada <masahiroy@...nel.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>
CC:     "linux-kbuild@...r.kernel.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>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] powerpc: clean up binutils version check



Le 27/08/2022 à 18:40, Masahiro Yamada a écrit :
> 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.
> 
> 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

Isn't this limitation only for ppc64le ?

Refer commit 60e065f70bdb ("powerpc: Reject binutils 2.24 when building 
little endian")

> +		# 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