[PATCH] arm64: move --fix-cortex-a53-843419 linker test to Kconfig

[PATCH] arm64: move --fix-cortex-a53-843419 linker test to Kconfig

[Masahiro Yamada]

$(call ld-option, --fix-cortex-a53-843419) in arch/arm64/Makefile is
evaluated every time even for Make targets that do not need the linker,
such as "make ARCH=arm64 install".

Recently, the Kbuild tree queued up a patch to avoid needless
compiler/linker flag evaluation. I beleive it is a good improvement
itself, but causing a false-positive warning for arm64 installation
in linux-next. (Thanks to Nathan for the report)

Kconfig can test the linker capability just once, and store it in the
.config file. The build and installation steps that follow do not need
to test the liniker over again.

Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

I was not sure what the preferred CONFIG option name is.
Please suggest a one if you have a better idea.


 arch/arm64/Kconfig  | 3 +++
 arch/arm64/Makefile | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5656e7aacd69..4a33428de8ac 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -521,6 +521,9 @@ config ARM64_ERRATUM_843419
 
 	  If unsure, say Y.
 
+config ARM64_LD_HAS_FIX_ERRATUM_843419
+	def_bool $(ld-option,--fix-cortex-a53-843419)
+
 config ARM64_ERRATUM_1024718
 	bool "Cortex-A55: 1024718: Update of DBM/AP bits without break before make might result in incorrect update"
 	default y
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 5b84aec31ed3..7ef44478560d 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -21,7 +21,7 @@ LDFLAGS_vmlinux		+= -shared -Bsymbolic -z notext \
 endif
 
 ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
-  ifeq ($(call ld-option, --fix-cortex-a53-843419),)
+  ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
 $(warning ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum)
   else
 LDFLAGS_vmlinux	+= --fix-cortex-a53-843419
-- 
2.27.0

Re: [PATCH] arm64: move --fix-cortex-a53-843419 linker test to Kconfig

[Will Deacon]

On Wed, Mar 24, 2021 at 04:11:28PM +0900, Masahiro Yamada wrote:
> $(call ld-option, --fix-cortex-a53-843419) in arch/arm64/Makefile is
> evaluated every time even for Make targets that do not need the linker,
> such as "make ARCH=arm64 install".
> 
> Recently, the Kbuild tree queued up a patch to avoid needless
> compiler/linker flag evaluation. I beleive it is a good improvement
> itself, but causing a false-positive warning for arm64 installation
> in linux-next. (Thanks to Nathan for the report)
> 
> Kconfig can test the linker capability just once, and store it in the
> .config file. The build and installation steps that follow do not need
> to test the liniker over again.
> 
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
> I was not sure what the preferred CONFIG option name is.
> Please suggest a one if you have a better idea.
> 
> 
>  arch/arm64/Kconfig  | 3 +++
>  arch/arm64/Makefile | 2 +-
>  2 files changed, 4 insertions(+), 1 deletion(-)

Acked-by: Will Deacon <will@kernel.org>

Will

Re: [PATCH] arm64: move --fix-cortex-a53-843419 linker test to Kconfig

[Nathan Chancellor]

On Wed, Mar 24, 2021 at 04:11:28PM +0900, Masahiro Yamada wrote:
> $(call ld-option, --fix-cortex-a53-843419) in arch/arm64/Makefile is
> evaluated every time even for Make targets that do not need the linker,
> such as "make ARCH=arm64 install".
> 
> Recently, the Kbuild tree queued up a patch to avoid needless
> compiler/linker flag evaluation. I beleive it is a good improvement
> itself, but causing a false-positive warning for arm64 installation
> in linux-next. (Thanks to Nathan for the report)
> 
> Kconfig can test the linker capability just once, and store it in the
> .config file. The build and installation steps that follow do not need
> to test the liniker over again.
> 
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>

Thanks for the quick fix!

> ---
> 
> I was not sure what the preferred CONFIG option name is.
> Please suggest a one if you have a better idea.
> 
> 
>  arch/arm64/Kconfig  | 3 +++
>  arch/arm64/Makefile | 2 +-
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 5656e7aacd69..4a33428de8ac 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -521,6 +521,9 @@ config ARM64_ERRATUM_843419
>  
>  	  If unsure, say Y.
>  
> +config ARM64_LD_HAS_FIX_ERRATUM_843419
> +	def_bool $(ld-option,--fix-cortex-a53-843419)
> +
>  config ARM64_ERRATUM_1024718
>  	bool "Cortex-A55: 1024718: Update of DBM/AP bits without break before make might result in incorrect update"
>  	default y
> diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
> index 5b84aec31ed3..7ef44478560d 100644
> --- a/arch/arm64/Makefile
> +++ b/arch/arm64/Makefile
> @@ -21,7 +21,7 @@ LDFLAGS_vmlinux		+= -shared -Bsymbolic -z notext \
>  endif
>  
>  ifeq ($(CONFIG_ARM64_ERRATUM_843419),y)
> -  ifeq ($(call ld-option, --fix-cortex-a53-843419),)
> +  ifneq ($(CONFIG_ARM64_LD_HAS_FIX_ERRATUM_843419),y)
>  $(warning ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum)
>    else
>  LDFLAGS_vmlinux	+= --fix-cortex-a53-843419
> -- 
> 2.27.0
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH] arm64: move --fix-cortex-a53-843419 linker test to Kconfig

[Catalin Marinas]

Hi Masahiro,

On Wed, Mar 24, 2021 at 04:11:28PM +0900, Masahiro Yamada wrote:
> $(call ld-option, --fix-cortex-a53-843419) in arch/arm64/Makefile is
> evaluated every time even for Make targets that do not need the linker,
> such as "make ARCH=arm64 install".
> 
> Recently, the Kbuild tree queued up a patch to avoid needless
> compiler/linker flag evaluation. I beleive it is a good improvement
> itself, but causing a false-positive warning for arm64 installation
> in linux-next. (Thanks to Nathan for the report)
> 
> Kconfig can test the linker capability just once, and store it in the
> .config file. The build and installation steps that follow do not need
> to test the liniker over again.
> 
> Reported-by: Nathan Chancellor <nathan@kernel.org>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
> I was not sure what the preferred CONFIG option name is.
> Please suggest a one if you have a better idea.
> 
> 
>  arch/arm64/Kconfig  | 3 +++
>  arch/arm64/Makefile | 2 +-
>  2 files changed, 4 insertions(+), 1 deletion(-)

Would you like this patch to go in via the arm64 tree or you will queue
it via the kbuild tree?

Thanks.

-- 
Catalin

Re: [PATCH] arm64: move --fix-cortex-a53-843419 linker test to Kconfig

[Masahiro Yamada]

On Fri, Mar 26, 2021 at 11:36 PM Catalin Marinas
<catalin.marinas@arm.com> wrote:
>
> Hi Masahiro,
>
> On Wed, Mar 24, 2021 at 04:11:28PM +0900, Masahiro Yamada wrote:
> > $(call ld-option, --fix-cortex-a53-843419) in arch/arm64/Makefile is
> > evaluated every time even for Make targets that do not need the linker,
> > such as "make ARCH=arm64 install".
> >
> > Recently, the Kbuild tree queued up a patch to avoid needless
> > compiler/linker flag evaluation. I beleive it is a good improvement
> > itself, but causing a false-positive warning for arm64 installation
> > in linux-next. (Thanks to Nathan for the report)
> >
> > Kconfig can test the linker capability just once, and store it in the
> > .config file. The build and installation steps that follow do not need
> > to test the liniker over again.
> >
> > Reported-by: Nathan Chancellor <nathan@kernel.org>
> > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > ---
> >
> > I was not sure what the preferred CONFIG option name is.
> > Please suggest a one if you have a better idea.
> >
> >
> >  arch/arm64/Kconfig  | 3 +++
> >  arch/arm64/Makefile | 2 +-
> >  2 files changed, 4 insertions(+), 1 deletion(-)
>
> Would you like this patch to go in via the arm64 tree or you will queue
> it via the kbuild tree?

I applied this to linux-kbuild with Will's Ack.
Thanks.




-- 
Best Regards
Masahiro Yamada

Re: [PATCH] arm64: move --fix-cortex-a53-843419 linker test to Kconfig

[Catalin Marinas]

On Sun, Mar 28, 2021 at 03:59:29PM +0900, Masahiro Yamada wrote:
> On Fri, Mar 26, 2021 at 11:36 PM Catalin Marinas
> <catalin.marinas@arm.com> wrote:
> > On Wed, Mar 24, 2021 at 04:11:28PM +0900, Masahiro Yamada wrote:
> > > $(call ld-option, --fix-cortex-a53-843419) in arch/arm64/Makefile is
> > > evaluated every time even for Make targets that do not need the linker,
> > > such as "make ARCH=arm64 install".
> > >
> > > Recently, the Kbuild tree queued up a patch to avoid needless
> > > compiler/linker flag evaluation. I beleive it is a good improvement
> > > itself, but causing a false-positive warning for arm64 installation
> > > in linux-next. (Thanks to Nathan for the report)
> > >
> > > Kconfig can test the linker capability just once, and store it in the
> > > .config file. The build and installation steps that follow do not need
> > > to test the liniker over again.
> > >
> > > Reported-by: Nathan Chancellor <nathan@kernel.org>
> > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> > > ---
> > >
> > > I was not sure what the preferred CONFIG option name is.
> > > Please suggest a one if you have a better idea.
> > >
> > >
> > >  arch/arm64/Kconfig  | 3 +++
> > >  arch/arm64/Makefile | 2 +-
> > >  2 files changed, 4 insertions(+), 1 deletion(-)
> >
> > Would you like this patch to go in via the arm64 tree or you will queue
> > it via the kbuild tree?
> 
> I applied this to linux-kbuild with Will's Ack.

Great, I'll cross it off my list. Thanks.

-- 
Catalin