lkml.org 
[lkml]   [2022]   [Jan]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 5.16 0354/1039] x86/boot/compressed: Move CLANG_FLAGS to beginning of KBUILD_CFLAGS
    Date
    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 431bf7f846c3c..e118136460518 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 += -Wundef
    KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
    @@ -47,7 +51,6 @@ 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.c indirectly inludes inat-table.h which is generated during
    # compilation and stored in $(objtree). Add the directory to the includes so
    --
    2.34.1


    \
     
     \ /
      Last update: 2022-01-25 01:13    [W:2.134 / U:0.216 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site