x86/lib/memmove_64.S: Convert memmove() to ALTERNATIVE macro

Make it execute the ERMS version if support is present and we're in the
forward memmove() part and remove the unfolded alternatives section
definition.

Signed-off-by: Borislav Petkov <bp@suse.de>

arch/x86/lib/memmove_64.S

@@ -5,7 +5,6 @@
  * This assembly file is re-written from memmove_64.c file.
  *	- Copyright 2011 Fenghua Yu <fenghua.yu@intel.com>
  */
-#define _STRING_C
 #include <linux/linkage.h>
 #include <asm/dwarf2.h>
 #include <asm/cpufeature.h>
@@ -44,6 +43,8 @@ ENTRY(__memmove)
 	jg 2f
 
 .Lmemmove_begin_forward:
+	ALTERNATIVE "", "movq %rdx, %rcx; rep movsb; retq", X86_FEATURE_ERMS
+
 	/*
 	 * movsq instruction have many startup latency
 	 * so we handle small size by general register.
@@ -207,21 +208,5 @@ ENTRY(__memmove)
 13:
 	retq
 	CFI_ENDPROC
-
-	.section .altinstr_replacement,"ax"
-.Lmemmove_begin_forward_efs:
-	/* Forward moving data. */
-	movq %rdx, %rcx
-	rep movsb
-	retq
-.Lmemmove_end_forward_efs:
-	.previous
-
-	.section .altinstructions,"a"
-	altinstruction_entry .Lmemmove_begin_forward,		\
-		.Lmemmove_begin_forward_efs,X86_FEATURE_ERMS,	\
-		.Lmemmove_end_forward-.Lmemmove_begin_forward,	\
-		.Lmemmove_end_forward_efs-.Lmemmove_begin_forward_efs,0
-	.previous
 ENDPROC(__memmove)
 ENDPROC(memmove)