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-rw-r--r--arch/powerpc/include/asm/membarrier.h28
1 files changed, 28 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/membarrier.h b/arch/powerpc/include/asm/membarrier.h
new file mode 100644
index 000000000..de7f79157
--- /dev/null
+++ b/arch/powerpc/include/asm/membarrier.h
@@ -0,0 +1,28 @@
+#ifndef _ASM_POWERPC_MEMBARRIER_H
+#define _ASM_POWERPC_MEMBARRIER_H
+
+static inline void membarrier_arch_switch_mm(struct mm_struct *prev,
+ struct mm_struct *next,
+ struct task_struct *tsk)
+{
+ /*
+ * Only need the full barrier when switching between processes.
+ * Barrier when switching from kernel to userspace is not
+ * required here, given that it is implied by mmdrop(). Barrier
+ * when switching from userspace to kernel is not needed after
+ * store to rq->curr.
+ */
+ if (IS_ENABLED(CONFIG_SMP) &&
+ likely(!(atomic_read(&next->membarrier_state) &
+ (MEMBARRIER_STATE_PRIVATE_EXPEDITED |
+ MEMBARRIER_STATE_GLOBAL_EXPEDITED)) || !prev))
+ return;
+
+ /*
+ * The membarrier system call requires a full memory barrier
+ * after storing to rq->curr, before going back to user-space.
+ */
+ smp_mb();
+}
+
+#endif /* _ASM_POWERPC_MEMBARRIER_H */