diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index c240efc74e007715ba766bb399ddce42e22be6cc..69b74a7b877f917cd3f0bc9014045a1ea70d9412 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -84,6 +84,7 @@ static inline void alternatives_smp_switch(int smp) {}
       "	 .byte " __stringify(feature) "\n"	/* feature bit     */	\
       "	 .byte 662b-661b\n"			/* sourcelen       */	\
       "	 .byte 664f-663f\n"			/* replacementlen  */	\
+      "	 .byte 0xff + (664f-663f) - (662b-661b)\n" /* rlen <= slen */	\
       ".previous\n"							\
       ".section .altinstr_replacement, \"ax\"\n"			\
       "663:\n\t" newinstr "\n664:\n"		/* replacement     */	\