On 14/05/2021 04:59, Nathan Chancellor wrote:
On 5/13/2021 4:59 AM, Alexey Kardashevskiy wrote:
The $(CPP) (do only preprocessing) macro is already defined in Makefile.
However POWERPC redefines it and adds $(KBUILD_CFLAGS) which results
in flags duplication. Which is not a big deal by itself except for
the flags which depend on other flags and the compiler checks them
as it parses the command line.
Specifically, scripts/Makefile.build:304 generates ksyms for .S files.
If clang+llvm+sanitizer are enabled, this results in
-emit-llvm-bc -fno-lto -flto -fvisibility=hidden \
-fsanitize=cfi-mfcall -fno-lto ...
in the clang command line and triggers error:
clang-13: error: invalid argument '-fsanitize=cfi-mfcall' only allowed
with '-flto'
This removes unnecessary CPP redefinition. Which works fine as in most
place KBUILD_CFLAGS is passed to $CPP except
arch/powerpc/kernel/vdso64/vdso(32|64).lds. To fix vdso, this does:
1. add -m(big|little)-endian to $CPP
2. add target to $KBUILD_CPPFLAGS as otherwise clang ignores
-m(big|little)-endian if
the building platform does not support big endian (such as x86).
Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
---
Changes:
v3:
* moved vdso cleanup in a separate patch
* only add target to KBUILD_CPPFLAGS for CLANG
v2:
* fix KBUILD_CPPFLAGS
* add CLANG_FLAGS to CPPFLAGS
---
Makefile | 1 +
arch/powerpc/Makefile | 3 ++-
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/Makefile b/Makefile
index 15b6476d0f89..5b545bef7653 100644
--- a/Makefile
+++ b/Makefile
@@ -576,6 +576,7 @@ CC_VERSION_TEXT = $(subst $(pound),,$(shell $(CC)
--version 2>/dev/null | head -
ifneq ($(findstring clang,$(CC_VERSION_TEXT)),)
ifneq ($(CROSS_COMPILE),)
CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
+KBUILD_CPPFLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%))
You can avoid the duplication here by just doing:
KBUILD_CPPFLAGS += $(CLANG_FLAGS)
This has potential of duplicating even more flags which is exactly what
I am trying to avoid here.
I am still not super happy about the flag duplication but I am not sure
I can think of a better solution. If KBUILD_CPPFLAGS are always included
when building .o files,
My understanding is that KBUILD_CPPFLAGS should not be added for .o. Who
does know or decide for sure about what CPPFLAGS are for? :)
maybe we should just add $(CLANG_FLAGS) to
KBUILD_CPPFLAGS instead of KBUILD_CFLAGS?
endif
ifeq ($(LLVM_IAS),1)
CLANG_FLAGS += -integrated-as
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 3212d076ac6a..306bfd2797ad 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -76,6 +76,7 @@ endif
ifdef CONFIG_CPU_LITTLE_ENDIAN
KBUILD_CFLAGS += -mlittle-endian
+KBUILD_CPPFLAGS += -mlittle-endian
KBUILD_LDFLAGS += -EL
LDEMULATION := lppc
GNUTARGET := powerpcle
@@ -83,6 +84,7 @@ 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
@@ -208,7 +210,6 @@ KBUILD_CPPFLAGS += -I $(srctree)/arch/$(ARCH)
$(asinstr)
KBUILD_AFLAGS += $(AFLAGS-y)
KBUILD_CFLAGS += $(call cc-option,-msoft-float)
KBUILD_CFLAGS += -pipe $(CFLAGS-y)
-CPP = $(CC) -E $(KBUILD_CFLAGS)
CHECKFLAGS += -m$(BITS) -D__powerpc__ -D__powerpc$(BITS)__
ifdef CONFIG_CPU_BIG_ENDIAN
--
Alexey
