[PATCH] ppc64: Add a sync in context switch on SMP

For the same reason as ppc32, we need to ensure that all stores
done on a CPU has reached the coherency domain and are visible
to loads done by another CPU when context switching as the same
thread may be rescheduled almost right away there.

diff --git a/arch/ppc64/kernel/entry.S b/arch/ppc64/kernel/entry.S
index 6ba2f90140af5d33732ca45d56e9802cc1bf6313..c106ce03e154c6d0629d6b1752928e35988fc75e 100644 (file)
--- a/arch/ppc64/kernel/entry.S
+++ b/arch/ppc64/kernel/entry.S
@@ -289,6 +289,14 @@ END_FTR_SECTION_IFSET(CPU_FTR_ALTIVEC)
        std     r23,_CCR(r1)
        std     r1,KSP(r3)      /* Set old stack pointer */
 
+#ifdef CONFIG_SMP
+       /* We need a sync somewhere here to make sure that if the
+        * previous task gets rescheduled on another CPU, it sees all
+        * stores it has performed on this one.
+        */
+       sync
+#endif /* CONFIG_SMP */
+
        addi    r6,r4,-THREAD   /* Convert THREAD to 'current' */
        std     r6,PACACURRENT(r13)     /* Set new 'current' */