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authorIngo Molnar <mingo@elte.hu>2011-05-18 20:59:27 +0200
committerIngo Molnar <mingo@elte.hu>2011-05-18 20:59:30 +0200
commit01ed58abec07633791f03684b937a7e22e00c9bb (patch)
tree7bb5b60c102aa08e404928ffcb3edf1e8404b5a2 /arch/x86/kernel/alternative.c
parentaf2d03d4aaa847ef41a229dfee098a47908437c6 (diff)
parent26afb7c661080ae3f1f13ddf7f0c58c4f931c22b (diff)
Merge branch 'x86/mem' into perf/core
Merge reason: memcpy_64.S changes an assumption perf bench has, so merge this here so we can fix it. Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/alternative.c')
-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);