[PATCH] powerpc/Makefile: Allow overriding CPP

[Nathan Chancellor]

On Thu, Nov 07, 2024 at 10:26:46PM +1100, Michael Ellerman wrote:
> From: Arnd Bergmann <arnd at arndb.de>
> 
> Unlike all other arches, powerpc doesn't allow the user to override CPP,
> because it sets it unconditionally in the arch Makefile. This can lead
> to strange build failures.
> 
> Instead add the required flags to KBUILD_CPPFLAGS, which are passed
> to CPP, CC and AS invocations by the generic Makefile logic.
> 
> Reported-by: Arnd Bergmann <arnd at arndb.de>
> Closes: https://lore.kernel.org/all/20240607061629.530301-1-arnd@kernel.org
> [mpe: Rebase, write change log]
> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>

My builds are still green with this change applied.

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

> ---
>  arch/powerpc/Makefile             | 7 +++----
>  arch/powerpc/kernel/vdso/Makefile | 2 +-
>  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index cbb353ddacb7..94a6ccb8ad12 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -62,14 +62,14 @@ KBUILD_LDFLAGS_MODULE += arch/powerpc/lib/crtsavres.o
>  endif
>  
>  ifdef CONFIG_CPU_LITTLE_ENDIAN
> -KBUILD_CFLAGS	+= -mlittle-endian
> +KBUILD_CPPFLAGS	+= -mlittle-endian
>  KBUILD_LDFLAGS	+= -EL
>  LDEMULATION	:= lppc
>  GNUTARGET	:= powerpcle
>  MULTIPLEWORD	:= -mno-multiple
>  KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-save-toc-indirect)
>  else
> -KBUILD_CFLAGS += $(call cc-option,-mbig-endian)
> +KBUILD_CPPFLAGS	+= $(call cc-option,-mbig-endian)
>  KBUILD_LDFLAGS	+= -EB
>  LDEMULATION	:= ppc
>  GNUTARGET	:= powerpc
> @@ -95,7 +95,7 @@ aflags-$(CONFIG_CPU_BIG_ENDIAN)		+= $(call cc-option,-mbig-endian)
>  aflags-$(CONFIG_CPU_LITTLE_ENDIAN)	+= -mlittle-endian
>  
>  ifeq ($(HAS_BIARCH),y)
> -KBUILD_CFLAGS	+= -m$(BITS)
> +KBUILD_CPPFLAGS	+= -m$(BITS)
>  KBUILD_AFLAGS	+= -m$(BITS)
>  KBUILD_LDFLAGS	+= -m elf$(BITS)$(LDEMULATION)
>  endif
> @@ -168,7 +168,6 @@ KBUILD_CPPFLAGS	+= -I $(srctree)/arch/powerpc $(asinstr)
>  KBUILD_AFLAGS	+= $(AFLAGS-y)
>  KBUILD_CFLAGS	+= $(CC_FLAGS_NO_FPU)
>  KBUILD_CFLAGS	+= $(CFLAGS-y)
> -CPP		= $(CC) -E $(KBUILD_CFLAGS)
>  
>  CHECKFLAGS	+= -m$(BITS) -D__powerpc__ -D__powerpc$(BITS)__
>  ifdef CONFIG_CPU_BIG_ENDIAN
> diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
> index 31ca5a547004..af130c82a71a 100644
> --- a/arch/powerpc/kernel/vdso/Makefile
> +++ b/arch/powerpc/kernel/vdso/Makefile
> @@ -50,7 +50,7 @@ ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
>  ldflags-$(CONFIG_LD_ORPHAN_WARN) += -Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
>  
>  # Filter flags that clang will warn are unused for linking
> -ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CFLAGS))
> +ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
>  
>  CC32FLAGS := -m32
>  CC32FLAGSREMOVE := -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc
> -- 
> 2.47.0
>