2 files changed, 9 insertions, 5 deletions

diff --git a/arch/x86/include/asm/alternative.h b/arch/x86/include/asm/alternative.h
index 3b5b828767b6..55fee12cea6d 100644
--- a/arch/x86/include/asm/alternative.h
+++ b/arch/x86/include/asm/alternative.h
@@ -28,12 +28,14 @@
  */
 
 #ifdef CONFIG_SMP
-#define LOCK_PREFIX \
+#define LOCK_PREFIX_HERE \
                 ".section .smp_locks,\"a\"\n"   \
                 _ASM_ALIGN "\n"                 \
-                _ASM_PTR "661f\n" /* address */ \
+                _ASM_PTR "671f\n" /* address */ \
                 ".previous\n"                   \
-                "661:\n\tlock; "
+                "671:"
+
+#define LOCK_PREFIX LOCK_PREFIX_HERE "\n\tlock; "
 
 #else /* ! CONFIG_SMP */
 #define LOCK_PREFIX ""
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 2589ea4c60ce..80b222ea4cf6 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -244,7 +244,8 @@ static void alternatives_smp_lock(u8 **start, u8 **end, u8 *text, u8 *text_end)
                 if (*ptr > text_end)
                         continue;
                 /* turn DS segment override prefix into lock prefix */
-                text_poke(*ptr, ((unsigned char []){0xf0}), 1);
+                if (**ptr == 0x3e)
+                        text_poke(*ptr, ((unsigned char []){0xf0}), 1);
         };
         mutex_unlock(&text_mutex);
 }
@@ -263,7 +264,8 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end
                 if (*ptr > text_end)
                         continue;
                 /* turn lock prefix into DS segment override prefix */
-                text_poke(*ptr, ((unsigned char []){0x3E}), 1);
+                if (**ptr == 0xf0)
+                        text_poke(*ptr, ((unsigned char []){0x3E}), 1);
         };
         mutex_unlock(&text_mutex);
 }