xtensa: add static function tracer support

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Chris Zankel <chris@zankel.net>

1 files changed, 50 insertions, 0 deletions

diff --git a/arch/xtensa/kernel/mcount.S b/arch/xtensa/kernel/mcount.S
new file mode 100644
index 000000000000..0eeda2e4a25e
--- /dev/null
+++ b/arch/xtensa/kernel/mcount.S
@@ -0,0 +1,50 @@
+/*
+ * arch/xtensa/kernel/mcount.S
+ *
+ * Xtensa specific mcount support
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2013 Tensilica Inc.
+ */
+
+#include <linux/linkage.h>
+#include <asm/ftrace.h>
+
+/*
+ * Entry condition:
+ *
+ *   a2:        a0 of the caller
+ */
+
+ENTRY(_mcount)
+
+        entry   a1, 16
+
+        movi    a4, ftrace_trace_function
+        l32i    a4, a4, 0
+        movi    a3, ftrace_stub
+        bne     a3, a4, 1f
+        retw
+
+1:      xor     a7, a2, a1
+        movi    a3, 0x3fffffff
+        and     a7, a7, a3
+        xor     a7, a7, a1
+
+        xor     a6, a0, a1
+        and     a6, a6, a3
+        xor     a6, a6, a1
+        addi    a6, a6, -MCOUNT_INSN_SIZE
+        callx4  a4
+
+        retw
+
+ENDPROC(_mcount)
+
+ENTRY(ftrace_stub)
+        entry   a1, 16
+        retw
+ENDPROC(ftrace_stub)