From: Nathan Chancellor nathan@kernel.org
[ Upstream commit 5fe392ff9d1f7254a1fbb3f72d9893088e4d23eb ]
When cross compiling i386_defconfig on an arm64 host with clang, there are a few instances of '-Waddress-of-packed-member' and '-Wgnu-variable-sized-type-not-at-end' in arch/x86/boot/compressed/, which should both be disabled with the cc-disable-warning calls in that directory's Makefile, which indicates that cc-disable-warning is failing at the point of testing these flags.
The cc-disable-warning calls fail because at the point that the flags are tested, KBUILD_CFLAGS has '-march=i386' without $(CLANG_FLAGS), which has the '--target=' flag to tell clang what architecture it is targeting. Without the '--target=' flag, the host architecture (arm64) is used and i386 is not a valid value for '-march=' in that case. This error can be seen by adding some logging to try-run:
clang-14: error: the clang compiler does not support '-march=i386'
Invoking the compiler has to succeed prior to calling cc-option or cc-disable-warning in order to accurately test whether or not the flag is supported; if it doesn't, the requested flag can never be added to the compiler flags. Move $(CLANG_FLAGS) to the beginning of KBUILD_FLAGS so that any new flags that might be added in the future can be accurately tested.
Fixes: d5cbd80e302d ("x86/boot: Add $(CLANG_FLAGS) to compressed KBUILD_CFLAGS") Signed-off-by: Nathan Chancellor nathan@kernel.org Signed-off-by: Borislav Petkov bp@suse.de Link: https://lore.kernel.org/r/20211222163040.1961481-1-nathan@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/boot/compressed/Makefile | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 6004047d25fdd..bf91e0a36d77f 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -28,7 +28,11 @@ KCOV_INSTRUMENT := n targets := vmlinux vmlinux.bin vmlinux.bin.gz vmlinux.bin.bz2 vmlinux.bin.lzma \ vmlinux.bin.xz vmlinux.bin.lzo vmlinux.bin.lz4 vmlinux.bin.zst
-KBUILD_CFLAGS := -m$(BITS) -O2 +# CLANG_FLAGS must come before any cc-disable-warning or cc-option calls in +# case of cross compiling, as it has the '--target=' flag, which is needed to +# avoid errors with '-march=i386', and future flags may depend on the target to +# be valid. +KBUILD_CFLAGS := -m$(BITS) -O2 $(CLANG_FLAGS) KBUILD_CFLAGS += -fno-strict-aliasing -fPIE KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING cflags-$(CONFIG_X86_32) := -march=i386 @@ -46,7 +50,6 @@ KBUILD_CFLAGS += -D__DISABLE_EXPORTS # Disable relocation relaxation in case the link is not PIE. KBUILD_CFLAGS += $(call as-option,-Wa$(comma)-mrelax-relocations=no) KBUILD_CFLAGS += -include $(srctree)/include/linux/hidden.h -KBUILD_CFLAGS += $(CLANG_FLAGS)
# sev-es.c indirectly inludes inat-table.h which is generated during # compilation and stored in $(objtree). Add the directory to the includes so