v4.19.13 snapshot.
diff --git a/arch/alpha/include/asm/futex.h b/arch/alpha/include/asm/futex.h
new file mode 100644
index 0000000..ca33225
--- /dev/null
+++ b/arch/alpha/include/asm/futex.h
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ALPHA_FUTEX_H
+#define _ASM_ALPHA_FUTEX_H
+
+#ifdef __KERNEL__
+
+#include <linux/futex.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+#include <asm/barrier.h>
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg) \
+ __asm__ __volatile__( \
+ __ASM_SMP_MB \
+ "1: ldl_l %0,0(%2)\n" \
+ insn \
+ "2: stl_c %1,0(%2)\n" \
+ " beq %1,4f\n" \
+ " mov $31,%1\n" \
+ "3: .subsection 2\n" \
+ "4: br 1b\n" \
+ " .previous\n" \
+ EXC(1b,3b,$31,%1) \
+ EXC(2b,3b,$31,%1) \
+ : "=&r" (oldval), "=&r"(ret) \
+ : "r" (uaddr), "r"(oparg) \
+ : "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("mov %3,%1\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ __futex_atomic_op("addl %0,%3,%1\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("or %0,%3,%1\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("andnot %0,%3,%1\n", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("xor %0,%3,%1\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, cmp;
+ u32 prev;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+ __asm__ __volatile__ (
+ __ASM_SMP_MB
+ "1: ldl_l %1,0(%3)\n"
+ " cmpeq %1,%4,%2\n"
+ " beq %2,3f\n"
+ " mov %5,%2\n"
+ "2: stl_c %2,0(%3)\n"
+ " beq %2,4f\n"
+ "3: .subsection 2\n"
+ "4: br 1b\n"
+ " .previous\n"
+ EXC(1b,3b,$31,%0)
+ EXC(2b,3b,$31,%0)
+ : "+r"(ret), "=&r"(prev), "=&r"(cmp)
+ : "r"(uaddr), "r"((long)(int)oldval), "r"(newval)
+ : "memory");
+
+ *uval = prev;
+ return ret;
+}
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_ALPHA_FUTEX_H */