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-rw-r--r--arch/x86/kernel/alternative.c9
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 651454b0c811..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);
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