4.9-stable review patch. If anyone has any objections, please let me know.
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From: Josh Poimboeuf jpoimboe@redhat.com
commit 867ac9d737094e46a6c33213f16dd1ec9e8bd5d5 upstream.
Objtool tries to silence 'unreachable instruction' warnings when it detects gcov is enabled, because gcov produces a lot of unreachable instructions and they don't really matter.
However, the 0-day bot is still reporting some unreachable instruction warnings with CONFIG_GCOV_KERNEL=y on GCC 4.6.4.
As it turns out, objtool's gcov detection doesn't work with older versions of GCC because they don't create a bunch of symbols with the 'gcov.' prefix like newer versions of GCC do.
Move the gcov check out of objtool and instead just create a new '--no-unreachable' flag which can be passed in by the kernel Makefile when CONFIG_GCOV_KERNEL is defined.
Also rename the 'nofp' variable to 'no_fp' for consistency with the new 'no_unreachable' variable.
Reported-by: kbuild test robot fengguang.wu@intel.com Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Fixes: 9cfffb116887 ("objtool: Skip all "unreachable instruction" warnings for gcov kernels") Link: http://lkml.kernel.org/r/c243dc78eb2ffdabb6e927844dea39b6033cd395.1500939244... Signed-off-by: Ingo Molnar mingo@kernel.org [just Makefile.build as the other parts of this patch already applied - gregkh] Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- scripts/Makefile.build | 3 +++ 1 file changed, 3 insertions(+)
--- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -253,6 +253,9 @@ objtool_args = check ifndef CONFIG_FRAME_POINTER objtool_args += --no-fp endif +ifdef CONFIG_GCOV_KERNEL +objtool_args += --no-unreachable +endif
# 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file