File-copy from v4.4.100

This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git

Please refer to that tree for all history prior to this point.

Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/tools/perf/arch/xtensa/util/Build b/tools/perf/arch/xtensa/util/Build
new file mode 100644
index 0000000..954e287
--- /dev/null
+++ b/tools/perf/arch/xtensa/util/Build
@@ -0,0 +1 @@
+libperf-$(CONFIG_DWARF) += dwarf-regs.o
diff --git a/tools/perf/arch/xtensa/util/dwarf-regs.c b/tools/perf/arch/xtensa/util/dwarf-regs.c
new file mode 100644
index 0000000..4dba76b
--- /dev/null
+++ b/tools/perf/arch/xtensa/util/dwarf-regs.c
@@ -0,0 +1,25 @@
+/*
+ * Mapping of DWARF debug register numbers into register names.
+ *
+ * Copyright (c) 2015 Cadence Design Systems Inc.
+ *
+ * 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 <stddef.h>
+#include <dwarf-regs.h>
+
+#define XTENSA_MAX_REGS 16
+
+const char *xtensa_regs_table[XTENSA_MAX_REGS] = {
+	"a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
+	"a8", "a9", "a10", "a11", "a12", "a13", "a14", "a15",
+};
+
+const char *get_arch_regstr(unsigned int n)
+{
+	return n < XTENSA_MAX_REGS ? xtensa_regs_table[n] : NULL;
+}