alternative_input
alternative_input("", "clflush (%[addr])", X86_BUG_CLFLUSH_MONITOR, [addr] "a" (addr));
alternative_input(BASE_PREFETCH, "prefetchnta %1",
alternative_input(BASE_PREFETCH, "prefetchw %1",
alternative_input("", "clflush (%[addr])", X86_BUG_CLFLUSH_MONITOR, [addr] "a" (addr));