powerpc: Perform an isync to synchronize CPUs coming out of secondary_hold

We need to do that to guarantee they see any code change done by
dynamic patching during boot.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
index 0700e1135c91..6d17c37f22a1 100644
--- a/arch/powerpc/kernel/head_64.S
+++ b/arch/powerpc/kernel/head_64.S
@@ -147,6 +147,8 @@ __secondary_hold:
         mtctr   r4
         mr      r3,r24
         li      r4,0
+        /* Make sure that patched code is visible */
+        isync
         bctr
 #else
         BUG_OPCODE