[ 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>

[ Upstream commit a73619a845d5625079cc1b3b820f44c899618388 ]

The __FILE__ macro is used everywhere in the kernel to locate the file
printing the log message, such as WARN_ON(), etc.  If the kernel is
built out of tree, this can be a long absolute path, like this:

  WARNING: CPU: 1 PID: 1 at /path/to/build/directory/arch/arm64/kernel/foo.c:...

This is because Kbuild runs in the objtree instead of the srctree,
then __FILE__ is expanded to a file path prefixed with $(srctree)/.

Commit 9da0763bdd82 ("kbuild: Use relative path when building in a
subdir of the source tree") improved this to some extent; $(srctree)
becomes ".." if the objtree is a child of the srctree.

For other cases of out-of-tree build, __FILE__ is still the absolute
path.  It also means the kernel image depends on where it was built.

A brand-new option from GCC, -fmacro-prefix-map, solves this problem.
If your compiler supports it, __FILE__ is the relative path from the
srctree regardless of O= option.  This provides more readable log and
more reproducible builds.

Please note __FILE__ is always an absolute path for external modules.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>