commite7607f7d6dupstream. ld.lld prior to 21.0.0 does not support using the KEEP keyword within an overlay description, which may be needed to avoid discarding necessary sections within an overlay with '--gc-sections', which can be enabled for the kernel via CONFIG_LD_DEAD_CODE_DATA_ELIMINATION. Disallow CONFIG_LD_DEAD_CODE_DATA_ELIMINATION without support for KEEP within OVERLAY and introduce a macro, OVERLAY_KEEP, that can be used to conditionally add KEEP when it is properly supported to avoid breaking old versions of ld.lld. Cc: stable@vger.kernel.org Link:381599f1feReviewed-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> [nathan: Fix conflict in init/Kconfig due to lack of RUSTC symbols] Signed-off-by: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>