objtool: Fix gcov check for older versions of GCC
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.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Fixes: 9cfffb116887 ("objtool: Skip all "unreachable instruction" warnings for gcov kernels")
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
5 files changed
