1 files changed, 10 insertions, 1 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 4a234677e213..1eeeafcb4410 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -210,6 +210,15 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
         u8 insnbuf[MAX_PATCH_LEN];
 
         DPRINTK("%s: alt table %p -> %p\n", __func__, start, end);
+        /*
+         * The scan order should be from start to end. A later scanned
+         * alternative code can overwrite a previous scanned alternative code.
+         * Some kernel functions (e.g. memcpy, memset, etc) use this order to
+         * patch code.
+         *
+         * So be careful if you want to change the scan order to any other
+         * order.
+         */
         for (a = start; a < end; a++) {
                 u8 *instr = a->instr;
                 BUG_ON(a->replacementlen > a->instrlen);
@@ -679,7 +688,7 @@ void __kprobes text_poke_smp_batch(struct text_poke_param *params, int n)
         __stop_machine(stop_machine_text_poke, (void *)&tpp, NULL);
 }
 
-#if defined(CONFIG_DYNAMIC_FTRACE) || defined(HAVE_JUMP_LABEL)
+#if defined(CONFIG_DYNAMIC_FTRACE) || defined(CONFIG_JUMP_LABEL)
 
 #ifdef CONFIG_X86_64
 unsigned char ideal_nop5[5] = { 0x66, 0x66, 0x66, 0x66, 0x90 };