[RFC PATCH 1/6] kbuild: factor the userspace ABI flags out into KBUILD_USERABI

[Sasha Levin <sashal@kernel.org>]

KBUILD_USERCFLAGS and KBUILD_USERLDFLAGS pick up the flags that select
the target ABI for userspace programs: --target= under clang, -m32/-m64,
or CONFIG_ARCH_USERFLAGS. Collect those in KBUILD_USERABI and export it,
so programs built outside of kbuild's userprogs can be compiled for the
same ABI without also inheriting kbuild's warning and language flags.

No functional change: KBUILD_USERCFLAGS and KBUILD_USERLDFLAGS keep the
same value.

Assisted-by: LLM
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 Makefile | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index 7c855e6fe5448..8c94aff229b21 100644
--- a/Makefile
+++ b/Makefile
@@ -650,7 +650,7 @@ export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AW
 export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
 export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD TAR
 export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS KBUILD_PROCMACROLDFLAGS LDFLAGS_MODULE
-export KBUILD_USERCFLAGS KBUILD_USERLDFLAGS
+export KBUILD_USERCFLAGS KBUILD_USERLDFLAGS KBUILD_USERABI
 
 export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS KBUILD_LDFLAGS
 export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE
@@ -1270,15 +1270,17 @@ endif
 USERFLAGS_FROM_KERNEL := --target=%
 
 ifdef CONFIG_ARCH_USERFLAGS
-KBUILD_USERCFLAGS += $(CONFIG_ARCH_USERFLAGS)
-KBUILD_USERLDFLAGS += $(CONFIG_ARCH_USERFLAGS)
+KBUILD_USERABI := $(CONFIG_ARCH_USERFLAGS)
 else
+KBUILD_USERABI :=
 # If not overridden also inherit the bit size
 USERFLAGS_FROM_KERNEL += -m32 -m64
 endif
 
-KBUILD_USERCFLAGS  += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
-KBUILD_USERLDFLAGS += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
+KBUILD_USERABI += $(filter $(USERFLAGS_FROM_KERNEL), $(KBUILD_CPPFLAGS) $(KBUILD_CFLAGS))
+
+KBUILD_USERCFLAGS  += $(KBUILD_USERABI)
+KBUILD_USERLDFLAGS += $(KBUILD_USERABI)
 
 # userspace programs are linked via the compiler, use the correct linker
 ifdef CONFIG_CC_IS_CLANG
-- 
2.53.0