Date:   Sun, 28 Aug 2022 03:03:31 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "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

On Sun, Aug 28, 2022 at 2:37 AM Christophe Leroy
<christophe.leroy@...roup.eu> wrote:
>
>
>
> 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")


I do not see any CONFIG check in the current checkbin.

Refer commit a3ad84da0760 ("powerpc/toc: Future proof
kernel toc")




-- 
Best Regards
Masahiro Yamada

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