From: Will Deacon <will@kernel.org>
Date: Fri, 4 Oct 2019 15:44:45 +0100
Subject: arm64: vdso32: Don't use KBUILD_CPPFLAGS unconditionally
Git-commit: c71e88c437962c1ec43d4d23a0ebf4c9cf9bee0d
Patch-mainline: 5.4-rc3
References: bnc#1151927 5.3.9

KBUILD_CPPFLAGS is defined differently depending on whether the main
compiler is clang or not. This means that it is not possible to build
the compat vDSO with GCC if the rest of the kernel is built with clang.

Define VDSO_CPPFLAGS directly to break this dependency and allow a clang
kernel to build a compat vDSO with GCC:

  $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- \
    CROSS_COMPILE_COMPAT=arm-linux-gnueabihf- CC=clang \
    COMPATCC=arm-linux-gnueabihf-gcc

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/arm64/kernel/vdso32/Makefile | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/vdso32/Makefile b/arch/arm64/kernel/vdso32/Makefile
index f52d29027d8d..7de96a6a56f9 100644
--- a/arch/arm64/kernel/vdso32/Makefile
+++ b/arch/arm64/kernel/vdso32/Makefile
@@ -31,11 +31,9 @@ cc32-as-instr = $(call try-run,\
 # arm64 one.
 # As a result we set our own flags here.
 
-# From top-level Makefile
-# NOSTDINC_FLAGS
-VDSO_CPPFLAGS := -nostdinc -isystem $(shell $(COMPATCC) -print-file-name=include)
+# KBUILD_CPPFLAGS and NOSTDINC_FLAGS from top-level Makefile
+VDSO_CPPFLAGS := -D__KERNEL__ -nostdinc -isystem $(shell $(COMPATCC) -print-file-name=include)
 VDSO_CPPFLAGS += $(LINUXINCLUDE)
-VDSO_CPPFLAGS += $(KBUILD_CPPFLAGS)
 
 # Common C and assembly flags
 # From top-level Makefile
-- 
2.24.0