parisc: add ftrace (function and graph tracer) functionality

This patch adds the ftrace debugging functionality to the parisc kernel.
It will currently only work with 64bit kernels, because the gcc options -pg
and -ffunction-sections can't be enabled at the same time and -ffunction-sections
is still needed to be able to link 32bit kernels.

Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

arch/parisc/include/asm/ftrace.h

@@ -0,0 +1,25 @@
+#ifndef _ASM_PARISC_FTRACE_H
+#define _ASM_PARISC_FTRACE_H
+
+#ifndef __ASSEMBLY__
+extern void mcount(void);
+
+/*
+ * Stack of return addresses for functions of a thread.
+ * Used in struct thread_info
+ */
+struct ftrace_ret_stack {
+	unsigned long ret;
+	unsigned long func;
+	unsigned long long calltime;
+};
+
+/*
+ * Primary handler of a function return.
+ * It relays on ftrace_return_to_handler.
+ * Defined in entry.S
+ */
+extern void return_to_handler(void);
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_PARISC_FTRACE_H */