git.oblomov.eu Git - linux-2.6/blob - kernel/trace/trace_functions_return.c

   1 /*
   2  *
   3  * Function return tracer.
   4  * Copyright (c) 2008 Frederic Weisbecker <fweisbec@gmail.com>
   5  * Mostly borrowed from function tracer which
   6  * is Copyright (c) Steven Rostedt <srostedt@redhat.com>
   7  *
   8  */
   9 #include <linux/debugfs.h>
  10 #include <linux/uaccess.h>
  11 #include <linux/ftrace.h>
  12 #include <linux/fs.h>
  13
  14 #include "trace.h"
  15
  16
  17 static int return_trace_init(struct trace_array *tr)
  18 {
  19         int cpu;
  20         for_each_online_cpu(cpu)
  21                 tracing_reset(tr, cpu);
  22
  23         return register_ftrace_return(&trace_function_return);
  24 }
  25
  26 static void return_trace_reset(struct trace_array *tr)
  27 {
  28                 unregister_ftrace_return();
  29 }
  30
  31
  32 enum print_line_t
  33 print_return_function(struct trace_iterator *iter)
  34 {
  35         struct trace_seq *s = &iter->seq;
  36         struct trace_entry *entry = iter->ent;
  37         struct ftrace_ret_entry *field;
  38         int ret;
  39
  40         if (entry->type == TRACE_FN_RET) {
  41                 trace_assign_type(field, entry);
  42                 ret = trace_seq_printf(s, "%pF -> ", (void *)field->parent_ip);
  43                 if (!ret)
  44                         return TRACE_TYPE_PARTIAL_LINE;
  45                 ret = seq_print_ip_sym(s, field->ip,
  46                                         trace_flags & TRACE_ITER_SYM_MASK);
  47                 if (!ret)
  48                         return TRACE_TYPE_PARTIAL_LINE;
  49                 ret = trace_seq_printf(s, " (%llu ns)\n",
  50                                         field->rettime - field->calltime);
  51                 if (!ret)
  52                         return TRACE_TYPE_PARTIAL_LINE;
  53                 else
  54                         return TRACE_TYPE_HANDLED;
  55         }
  56         return TRACE_TYPE_UNHANDLED;
  57 }
  58
  59 static struct tracer return_trace __read_mostly =
  60 {
  61         .name        = "return",
  62         .init        = return_trace_init,
  63         .reset       = return_trace_reset,
  64         .print_line = print_return_function
  65 };
  66
  67 static __init int init_return_trace(void)
  68 {
  69         return register_tracer(&return_trace);
  70 }
  71
  72 device_initcall(init_return_trace);