v4.19.13 snapshot.
diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h
new file mode 100644
index 0000000..eb887dd
--- /dev/null
+++ b/arch/arc/include/asm/futex.h
@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * Vineetg: August 2010: From Android kernel work
+ */
+
+#ifndef _ASM_FUTEX_H
+#define _ASM_FUTEX_H
+
+#include <linux/futex.h>
+#include <linux/preempt.h>
+#include <linux/uaccess.h>
+#include <asm/errno.h>
+
+#ifdef CONFIG_ARC_HAS_LLSC
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
+ \
+ smp_mb(); \
+ __asm__ __volatile__( \
+ "1: llock %1, [%2] \n" \
+ insn "\n" \
+ "2: scond %0, [%2] \n" \
+ " bnz 1b \n" \
+ " mov %0, 0 \n" \
+ "3: \n" \
+ " .section .fixup,\"ax\" \n" \
+ " .align 4 \n" \
+ "4: mov %0, %4 \n" \
+ " j 3b \n" \
+ " .previous \n" \
+ " .section __ex_table,\"a\" \n" \
+ " .align 4 \n" \
+ " .word 1b, 4b \n" \
+ " .word 2b, 4b \n" \
+ " .previous \n" \
+ \
+ : "=&r" (ret), "=&r" (oldval) \
+ : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
+ : "cc", "memory"); \
+ smp_mb() \
+
+#else /* !CONFIG_ARC_HAS_LLSC */
+
+#define __futex_atomic_op(insn, ret, oldval, uaddr, oparg)\
+ \
+ smp_mb(); \
+ __asm__ __volatile__( \
+ "1: ld %1, [%2] \n" \
+ insn "\n" \
+ "2: st %0, [%2] \n" \
+ " mov %0, 0 \n" \
+ "3: \n" \
+ " .section .fixup,\"ax\" \n" \
+ " .align 4 \n" \
+ "4: mov %0, %4 \n" \
+ " j 3b \n" \
+ " .previous \n" \
+ " .section __ex_table,\"a\" \n" \
+ " .align 4 \n" \
+ " .word 1b, 4b \n" \
+ " .word 2b, 4b \n" \
+ " .previous \n" \
+ \
+ : "=&r" (ret), "=&r" (oldval) \
+ : "r" (uaddr), "r" (oparg), "ir" (-EFAULT) \
+ : "cc", "memory"); \
+ smp_mb() \
+
+#endif
+
+static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval,
+ u32 __user *uaddr)
+{
+ int oldval = 0, ret;
+
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_disable(); /* to guarantee atomic r-m-w of futex op */
+#endif
+ pagefault_disable();
+
+ switch (op) {
+ case FUTEX_OP_SET:
+ __futex_atomic_op("mov %0, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ADD:
+ /* oldval = *uaddr; *uaddr += oparg ; ret = *uaddr */
+ __futex_atomic_op("add %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_OR:
+ __futex_atomic_op("or %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_ANDN:
+ __futex_atomic_op("bic %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ case FUTEX_OP_XOR:
+ __futex_atomic_op("xor %0, %1, %3", ret, oldval, uaddr, oparg);
+ break;
+ default:
+ ret = -ENOSYS;
+ }
+
+ pagefault_enable();
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_enable();
+#endif
+
+ if (!ret)
+ *oval = oldval;
+
+ return ret;
+}
+
+/*
+ * cmpxchg of futex (pagefaults disabled by caller)
+ * Return 0 for success, -EFAULT otherwise
+ */
+static inline int
+futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 expval,
+ u32 newval)
+{
+ int ret = 0;
+ u32 existval;
+
+ if (!access_ok(VERIFY_WRITE, uaddr, sizeof(u32)))
+ return -EFAULT;
+
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_disable(); /* to guarantee atomic r-m-w of futex op */
+#endif
+ smp_mb();
+
+ __asm__ __volatile__(
+#ifdef CONFIG_ARC_HAS_LLSC
+ "1: llock %1, [%4] \n"
+ " brne %1, %2, 3f \n"
+ "2: scond %3, [%4] \n"
+ " bnz 1b \n"
+#else
+ "1: ld %1, [%4] \n"
+ " brne %1, %2, 3f \n"
+ "2: st %3, [%4] \n"
+#endif
+ "3: \n"
+ " .section .fixup,\"ax\" \n"
+ "4: mov %0, %5 \n"
+ " j 3b \n"
+ " .previous \n"
+ " .section __ex_table,\"a\" \n"
+ " .align 4 \n"
+ " .word 1b, 4b \n"
+ " .word 2b, 4b \n"
+ " .previous\n"
+ : "+&r"(ret), "=&r"(existval)
+ : "r"(expval), "r"(newval), "r"(uaddr), "ir"(-EFAULT)
+ : "cc", "memory");
+
+ smp_mb();
+
+#ifndef CONFIG_ARC_HAS_LLSC
+ preempt_enable();
+#endif
+ *uval = existval;
+ return ret;
+}
+
+#endif