arch/x86/lib/copy_user_64.S | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/lib/copy_user_64.S b/arch/x86/lib/copy_user_64.S
index 4fc5c2de2de4..21f11bd36cdc 100644
--- a/arch/x86/lib/copy_user_64.S
+++ b/arch/x86/lib/copy_user_64.S
@@ -7,9 +7,17 @@
  */
 
 #include <linux/linkage.h>
+#include <asm/alternative.h>
 #include <asm/asm.h>
 #include <asm/export.h>
 
+/*
+ * Disgusting hack to generate a two-byte 'jae' instruction
+ * for 'alternatives' that would otherwise generate a relocation
+ * and a big jump.
+ */
+#define JAE(x) ".byte 0x73," #x "-0b-2"
+
 /*
  * rep_movs_alternative - memory copy with exception handling.
  * This version is for CPUs that don't have FSRM (Fast Short Rep Movs)
@@ -29,7 +37,7 @@
  */
 SYM_FUNC_START(rep_movs_alternative)
 	cmpq $64,%rcx
-	jae .Lunrolled
+0:	alternative JAE(.Lunrolled), JAE(.Llarge), X86_FEATURE_ERMS
 
 	cmp $8,%ecx
 	jae .Lword
@@ -65,6 +73,12 @@ SYM_FUNC_START(rep_movs_alternative)
 	_ASM_EXTABLE_UA( 2b, .Lcopy_user_tail)
 	_ASM_EXTABLE_UA( 3b, .Lcopy_user_tail)
 
+.Llarge:
+0:	rep movsb
+1:	RET
+
+        _ASM_EXTABLE_UA( 0b, 1b)
+
 	.p2align 4
 .Lunrolled:
 10:	movq (%rsi),%r8