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ld.lld 16.0.0 and newer defaults to '--no-undefined-version', which causes the following error when CONFIG_MIPS_CLOCK_VSYSCALL is not set: ld.lld: error: version script assignment of 'LINUX_2.6' to symbol '__vdso_gettimeofday' failed: symbol not defined Only export __vdso_gettimeofday() when it will be present in the final object file, which clears up the error. Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202308170532.zxFFv25c-lkp@intel.com/ Signed-off-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Fangrui Song <maskray@google.com> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>