v4.19.13 snapshot.
diff --git a/arch/powerpc/include/asm/futex.h b/arch/powerpc/include/asm/futex.h
new file mode 100644
index 0000000..9454277
--- /dev/null
+++ b/arch/powerpc/include/asm/futex.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_POWERPC_FUTEX_H
+#define _ASM_POWERPC_FUTEX_H
+
+#ifdef __KERNEL__
+
+#include <linux/futex.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+#include <asm/synch.h>
+#include <asm/asm-405.h>
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
+ __asm__ __volatile ( \
+ PPC_ATOMIC_ENTRY_BARRIER \
+"1: lwarx %0,0,%2\n" \
+ insn \
+ PPC405_ERR77(0, %2) \
+"2: stwcx. %1,0,%2\n" \
+ "bne- 1b\n" \
+ PPC_ATOMIC_EXIT_BARRIER \
+ "li %1,0\n" \
+"3: .section .fixup,\"ax\"\n" \
+"4: li %1,%3\n" \
+ "b 3b\n" \
+ ".previous\n" \
+ EX_TABLE(1b, 4b) \
+ EX_TABLE(2b, 4b) \
+ : "=&r" (oldval), "=&r" (ret) \
+ : "b" (uaddr), "i" (-EFAULT), "r" (oparg) \
+ : "cr0", "memory")
+
+static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
+ u32 __user *uaddr)
+{
+ int oldval = 0, ret;
+
+ pagefault_disable();
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("mr %1,%4\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("add %1,%0,%4\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("or %1,%0,%4\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("andc %1,%0,%4\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("xor %1,%0,%4\n", ret, oldval, uaddr, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+
+ pagefault_enable();
+
+ if (!ret)
+ *oval = oldval;
+
+ return ret;
+}
+
+static inline int
+futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
+ u32 oldval, u32 newval)
+{
+ int ret = 0;
+ u32 prev;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ __asm__ __volatile__ (
+ PPC_ATOMIC_ENTRY_BARRIER
+"1: lwarx %1,0,%3 # futex_atomic_cmpxchg_inatomic\n\
+ cmpw 0,%1,%4\n\
+ bne- 3f\n"
+ PPC405_ERR77(0,%3)
+"2: stwcx. %5,0,%3\n\
+ bne- 1b\n"
+ PPC_ATOMIC_EXIT_BARRIER
+"3: .section .fixup,\"ax\"\n\
+4: li %0,%6\n\
+ b 3b\n\
+ .previous\n"
+ EX_TABLE(1b, 4b)
+ EX_TABLE(2b, 4b)
+ : "+r" (ret), "=&r" (prev), "+m" (*uaddr)
+ : "r" (uaddr), "r" (oldval), "r" (newval), "i" (-EFAULT)
+ : "cc", "memory");
+
+ *uval = prev;
+ return ret;
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_POWERPC_FUTEX_H */