commit 5241ab4cf4 upstream.
CLANG_FLAGS is initialized by the following line:
CLANG_FLAGS := --target=$(notdir $(CROSS_COMPILE:%-=%))
..., which is run only when CROSS_COMPILE is set.
Some build targets (bindeb-pkg etc.) recurse to the top Makefile.
When you build the kernel with Clang but without CROSS_COMPILE,
the same compiler flags such as -no-integrated-as are accumulated
into CLANG_FLAGS.
If you run 'make CC=clang' and then 'make CC=clang bindeb-pkg',
Kbuild will recompile everything needlessly due to the build command
change.
Fix this by correctly initializing CLANG_FLAGS.
Fixes: 238bcbc4e0 ("kbuild: consolidate Clang compiler flags")
Cc: <stable@vger.kernel.org> # v5.0+
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 589834b3a0 ]
In commit ebcc5928c5 ("arm64: Silence gcc warnings about arch ABI
drift"), the arm64 Makefile added -Wno-psabi to KBUILD_CFLAGS, which is
a GCC only option so clang rightfully complains:
warning: unknown warning option '-Wno-psabi' [-Wunknown-warning-option]
https://clang.llvm.org/docs/DiagnosticsReference.html#wunknown-warning-option
However, by default, this is merely a warning so the build happily goes
on with a slew of these warnings in the process.
Commit c3f0d0bc5b ("kbuild, LLVMLinux: Add -Werror to cc-option to
support clang") worked around this behavior in cc-option by adding
-Werror so that unknown flags cause an error. However, this all happens
silently and when an unknown flag is added to the build unconditionally
like -Wno-psabi, cc-option will always fail because there is always an
unknown flag in the list of flags. This manifested as link time failures
in the arm64 libstub because -fno-stack-protector didn't get added to
KBUILD_CFLAGS.
To avoid these weird cryptic failures in the future, make clang behave
like gcc and immediately error when it encounters an unknown flag by
adding -Werror=unknown-warning-option to CLANG_FLAGS. This can be added
unconditionally for clang because it is supported by at least 3.0.0,
according to godbolt [1] and 4.0.0, according to its documentation [2],
which is far earlier than we typically support.
[1]: https://godbolt.org/z/7F7rm3
[2]: https://releases.llvm.org/4.0.0/tools/clang/docs/DiagnosticsReference.html#wunknown-warning-option
Link: https://github.com/ClangBuiltLinux/linux/issues/511
Link: https://github.com/ClangBuiltLinux/linux/issues/517
Suggested-by: Peter Smith <peter.smith@linaro.org>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 6f303d6053 upstream.
We already did this for clang, but now gcc has that warning too. Yes,
yes, the address may be unaligned. And that's kind of the point.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit a75bb4eb9e upstream.
The clang option -Oz enables *aggressive* optimization for size,
which doesn't necessarily result in smaller images, but can have
negative impact on performance. Switch back to the less aggressive
-Os.
This reverts commit 6748cb3c29.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit ad15006cc7 upstream.
This causes an issue when trying to build with `make LD=ld.lld` if
ld.lld and the rest of your cross tools aren't in the same directory
(ex. /usr/local/bin) (as is the case for Android's build system), as the
GCC_TOOLCHAIN_DIR then gets set based on `which $(LD)` which will point
where LLVM tools are, not GCC/binutils tools are located.
Instead, select the GCC_TOOLCHAIN_DIR based on another tool provided by
binutils for which LLVM does not provide a substitute for, such as
elfedit.
Fixes: 785f11aa59 ("kbuild: Add better clang cross build support")
Link: https://github.com/ClangBuiltLinux/linux/issues/341
Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 3bd9805090 upstream.
The powerpc makefile will use these in it's boot wrapper.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 238bcbc4e0 upstream.
Collect basic Clang options such as --target, --prefix, --gcc-toolchain,
-no-integrated-as into a single variable CLANG_FLAGS so that it can be
easily reused in other parts of Makefile.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit dbe27a002e upstream.
We are still a way off the Clang's integrated assembler support for
the kernel. Hence, -no-integrated-as is mandatory to build the kernel
with Clang. If you had an ancient version of Clang that does not
recognize this option, you would not be able to compile the kernel
anyway.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit ef7cfd00b2 ]
For the same reason as commit 25896d073d ("x86/build: Fix compiler
support check for CONFIG_RETPOLINE"), you cannot put this $(error ...)
into the parse stage of the top Makefile.
Perhaps I'd propose a more sophisticated solution later, but this is
the best I can do for now.
Link: https://lkml.org/lkml/2017/12/25/211
Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Reported-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reported-by: Qian Cai <cai@lca.pw>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Tested-by: Qian Cai <cai@lca.pw>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 217c3e0196 upstream.
They are too noisy
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ef8c4ed9db upstream.
When using a GCC cross toolchain which is not in a compiled in
Clang search path, Clang reverts to the system assembler and
linker. This leads to assembler or linker errors, depending on
which tool is first used for a given architecture.
It seems that Clang is not searching $PATH for a matching
assembler or linker.
Make sure that Clang picks up the correct assembler or linker by
passing the cross compilers bin directory as search path.
This allows to use Clang provided by distributions with GCC
toolchains not in /usr/bin.
Link: https://github.com/ClangBuiltLinux/linux/issues/78
Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-and-tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
[nc: Adjust context]
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 0f0e8de334 ]
In order to make sure compiler flag detection for ARM works
correctly the no-integrated-as flags need to be set before
including the arch specific Makefile.
Fixes: cfe17c9bbe ("kbuild: move cc-option and cc-disable-warning after incl. arch Makefile")
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 2e549b2ee0 upstream.
Currently, if the vDSO ends up containing an indirect branch or
call, GCC will emit the "external thunk" style of retpoline, and it
will fail to link.
Fix it by building the vDSO with inline retpoline thunks.
I haven't seen any reports of this triggering on an unpatched
kernel.
Fixes: commit 76b043848f ("x86/retpoline: Add initial retpoline support")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Matt Rickard <matt@softrans.com.au>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jason Vas Dias <jason.vas.dias@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/c76538cd3afbe19c6246c2d1715bc6a60bd63985.1534448381.git.luto@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 6d79a7b424 ]
Suppress warnings for systems that do not recognize LFS_*.
getconf: no such configuration parameter `LFS_CFLAGS'
getconf: no such configuration parameter `LFS_LDFLAGS'
getconf: no such configuration parameter `LFS_LIBS'
Fixes: d7f14c66c2 ("kbuild: Enable Large File Support for hostprogs")
Reported-by: Chen Feng <puck.chen@hisilicon.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
