text: /*
   * Code for tracing calls in Linux kernel.
   * Copyright (C) 2009-2016 Helge Deller <deller@gmx.de>
   *
   * based on code for x86 which is:
   * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
   *
   * future possible enhancements:
   * 	- add CONFIG_DYNAMIC_FTRACE
   *	- add CONFIG_STACK_TRACER
   */
  
  #include <linux/init.h>
  #include <linux/ftrace.h>
  
  #include <asm/assembly.h>
  #include <asm/sections.h>
  #include <asm/ftrace.h>
  
  
  #define __hot __attribute__ ((__section__ (".text.hot")))
  
  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  /*
   * Hook the return address and push it in the stack of return addrs
   * in current thread info.
   */
  static void __hot prepare_ftrace_return(unsigned long *parent,
  					unsigned long self_addr)
  {
  	unsigned long old;
  	struct ftrace_graph_ent trace;
  	extern int parisc_return_to_handler;
  
  	if (unlikely(ftrace_graph_is_dead()))
  		return;
  
  	if (unlikely(atomic_read(&current->tracing_graph_pause)))
  		return;
  
  	old = *parent;
  
  	trace.func = self_addr;
  	trace.depth = current->curr_ret_stack + 1;
  
  	/* Only trace if the calling function expects to */
  	if (!ftrace_graph_entry(&trace))
  		return;
  
          if (ftrace_push_return_trace(old, self_addr, &trace.depth,
  			0 ) == -EBUSY)
                  return;
  
  	/* activate parisc_return_to_handler() as return point */
  	*parent = (unsigned long) &parisc_return_to_handler;
  }
  #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
  
  void notrace __hot ftrace_function_trampoline(unsigned long parent,
  				unsigned long self_addr,
  				unsigned long org_sp_gr3)
  {
  	extern ftrace_func_t ftrace_trace_function;  /* depends on CONFIG_DYNAMIC_FTRACE */
  	extern int ftrace_graph_entry_stub(struct ftrace_graph_ent *trace);
  
  	if (ftrace_trace_function != ftrace_stub) {
  		/* struct ftrace_ops *op, struct pt_regs *regs); */
  		ftrace_trace_function(parent, self_addr, NULL, NULL);
  		return;
  	}
  
  #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  	if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub ||
  		ftrace_graph_entry != ftrace_graph_entry_stub) {
  		unsigned long *parent_rp;
  
  		/* calculate pointer to %rp in stack */
  		parent_rp = (unsigned long *) (org_sp_gr3 - RP_OFFSET);
  		/* sanity check: parent_rp should hold parent */
  		if (*parent_rp != parent)
  			return;
  
  		prepare_ftrace_return(parent_rp, self_addr);
  		return;
  	}
  #endif
  }
  
  