[ Upstream commit e00d8880481497474792d28c14479a9fb6752046 ]
Commit c3ff2a5193fa ("powerpc/32: add stack protector support")
caused kernel panic on PowerPC when an external module is used with
CONFIG_STACKPROTECTOR because the 'prepare' target was not executed
for the external module build.
Commit e07db28eea38 ("kbuild: fix single target build for external
module") turned it into a build error because the 'prepare' target is
now executed but the 'prepare0' target is missing for the external
module build.
External module on arm/arm64 with CONFIG_STACKPROTECTOR_PER_TASK is
also broken in the same way.
Move 'PHONY += prepare0' to the common place. GNU Make is fine with
missing rule for phony targets. I also removed the comment which is
wrong irrespective of this commit.
I minimize the change so it can be easily backported to 4.20.x
To fix v4.20, please backport e07db28eea38 ("kbuild: fix single target
build for external module"), and then this commit.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=201891
Fixes: e07db28eea38 ("kbuild: fix single target build for external module")
Fixes: c3ff2a5193fa ("powerpc/32: add stack protector support")
Fixes: 189af4657186 ("ARM: smp: add support for per-task stack canaries")
Fixes: 0a1213fa7432 ("arm64: enable per-task stack canaries")
Cc: linux-stable <stable@vger.kernel.org> # v4.20
Reported-by: Samuel Holland <samuel@sholland.org>
Reported-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e07db28eea38ed4e332b3a89f3995c86b713cb5b ]
Building a single target in an external module fails due to missing
.tmp_versions directory.
For example,
$ make -C /lib/modules/$(uname -r)/build M=$PWD foo.o
will fail in the following way:
CC [M] /home/masahiro/foo/foo.o
/bin/sh: 1: cannot create /home/masahiro/foo/.tmp_versions/foo.mod: Directory nonexistent
This is because $(cmd_crmodverdir) is executed only before building
/, %/, %.ko single targets of external modules. Create .tmp_versions
in the 'prepare' target.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 29be86d7f9cb18df4123f309ac7857570513e8bc ]
The gcc -fcf-protection=branch option is not compatible with
-mindirect-branch=thunk-extern. The latter is used when
CONFIG_RETPOLINE is selected, and this will fail to build with
a gcc which has -fcf-protection=branch enabled by default. Adding
-fcf-protection=none when building with retpoline enabled
prevents such build failures.
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 5241ab4cf42d3a93b933b55d3d53f43049081fa1 upstream.
CLANG_FLAGS is initialized by the following line:
CLANG_FLAGS := --target=$(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: 238bcbc4e07f ("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 589834b3a0097a4908f4112eac0ca2feb486fa32 ]
In commit ebcc5928c5d9 ("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>
