[PATCH] powerpc/Makefile: Allow overriding CPP

[Michael Ellerman]

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>
---
 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