v4.19.13 snapshot.
diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
new file mode 100644
index 0000000..35a0ef9
--- /dev/null
+++ b/arch/powerpc/lib/locks.c
@@ -0,0 +1,69 @@
+/*
+ * Spin and read/write lock operations.
+ *
+ * Copyright (C) 2001-2004 Paul Mackerras <paulus@au.ibm.com>, IBM
+ * Copyright (C) 2001 Anton Blanchard <anton@au.ibm.com>, IBM
+ * Copyright (C) 2002 Dave Engebretsen <engebret@us.ibm.com>, IBM
+ * Rework to support virtual processors
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/export.h>
+#include <linux/smp.h>
+
+/* waiting for a spinlock... */
+#if defined(CONFIG_PPC_SPLPAR)
+#include <asm/hvcall.h>
+#include <asm/smp.h>
+
+void __spin_yield(arch_spinlock_t *lock)
+{
+ unsigned int lock_value, holder_cpu, yield_count;
+
+ lock_value = lock->slock;
+ if (lock_value == 0)
+ return;
+ holder_cpu = lock_value & 0xffff;
+ BUG_ON(holder_cpu >= NR_CPUS);
+ yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
+ if ((yield_count & 1) == 0)
+ return; /* virtual cpu is currently running */
+ rmb();
+ if (lock->slock != lock_value)
+ return; /* something has changed */
+ plpar_hcall_norets(H_CONFER,
+ get_hard_smp_processor_id(holder_cpu), yield_count);
+}
+EXPORT_SYMBOL_GPL(__spin_yield);
+
+/*
+ * Waiting for a read lock or a write lock on a rwlock...
+ * This turns out to be the same for read and write locks, since
+ * we only know the holder if it is write-locked.
+ */
+void __rw_yield(arch_rwlock_t *rw)
+{
+ int lock_value;
+ unsigned int holder_cpu, yield_count;
+
+ lock_value = rw->lock;
+ if (lock_value >= 0)
+ return; /* no write lock at present */
+ holder_cpu = lock_value & 0xffff;
+ BUG_ON(holder_cpu >= NR_CPUS);
+ yield_count = be32_to_cpu(lppaca_of(holder_cpu).yield_count);
+ if ((yield_count & 1) == 0)
+ return; /* virtual cpu is currently running */
+ rmb();
+ if (rw->lock != lock_value)
+ return; /* something has changed */
+ plpar_hcall_norets(H_CONFER,
+ get_hard_smp_processor_id(holder_cpu), yield_count);
+}
+#endif