arch/blackfin/kernel/ftrace.c

   1 /*
   2  * ftrace graph code
   3  *
   4  * Copyright (C) 2009 Analog Devices Inc.
   5  * Licensed under the GPL-2 or later.
   6  */
   7
   8 #include <linux/ftrace.h>
   9 #include <linux/kernel.h>
  10 #include <linux/sched.h>
  11 #include <asm/atomic.h>
  12
  13 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
  14
  15 /*
  16  * Hook the return address and push it in the stack of return addrs
  17  * in current thread info.
  18  */
  19 void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr)
  20 {
  21         struct ftrace_graph_ent trace;
  22         unsigned long return_hooker = (unsigned long)&return_to_handler;
  23
  24         if (unlikely(atomic_read(&current->tracing_graph_pause)))
  25                 return;
  26
  27         if (ftrace_push_return_trace(*parent, self_addr, &trace.depth) == -EBUSY)
  28                 return;
  29
  30         trace.func = self_addr;
  31
  32         /* Only trace if the calling function expects to */
  33         if (!ftrace_graph_entry(&trace)) {
  34                 current->curr_ret_stack--;
  35                 return;
  36         }
  37
  38         /* all is well in the world !  hijack RETS ... */
  39         *parent = return_hooker;
  40 }
  41
  42 #endif