SAFE public projects git trees. - safe/jmp/linux-2.6/blob - kernel/trace/trace_functions_graph.c

   1 /*
   2  *
   3  * Function graph 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 #define TRACE_GRAPH_PRINT_OVERRUN       0x1
  18 static struct tracer_opt trace_opts[] = {
  19         /* Display overruns or not */
  20         { TRACER_OPT(overrun, TRACE_GRAPH_PRINT_OVERRUN) },
  21         { } /* Empty entry */
  22 };
  23
  24 static struct tracer_flags tracer_flags = {
  25         .val = 0, /* Don't display overruns by default */
  26         .opts = trace_opts
  27 };
  28
  29
  30 static int graph_trace_init(struct trace_array *tr)
  31 {
  32         int cpu;
  33         for_each_online_cpu(cpu)
  34                 tracing_reset(tr, cpu);
  35
  36         return register_ftrace_graph(&trace_function_graph);
  37 }
  38
  39 static void graph_trace_reset(struct trace_array *tr)
  40 {
  41                 unregister_ftrace_graph();
  42 }
  43
  44
  45 enum print_line_t
  46 print_graph_function(struct trace_iterator *iter)
  47 {
  48         struct trace_seq *s = &iter->seq;
  49         struct trace_entry *entry = iter->ent;
  50         struct ftrace_graph_entry *field;
  51         int ret;
  52
  53         if (entry->type == TRACE_FN_RET) {
  54                 trace_assign_type(field, entry);
  55                 ret = trace_seq_printf(s, "%pF -> ", (void *)field->parent_ip);
  56                 if (!ret)
  57                         return TRACE_TYPE_PARTIAL_LINE;
  58
  59                 ret = seq_print_ip_sym(s, field->ip,
  60                                         trace_flags & TRACE_ITER_SYM_MASK);
  61                 if (!ret)
  62                         return TRACE_TYPE_PARTIAL_LINE;
  63
  64                 ret = trace_seq_printf(s, " (%llu ns)",
  65                                         field->rettime - field->calltime);
  66                 if (!ret)
  67                         return TRACE_TYPE_PARTIAL_LINE;
  68
  69                 if (tracer_flags.val & TRACE_GRAPH_PRINT_OVERRUN) {
  70                         ret = trace_seq_printf(s, " (Overruns: %lu)",
  71                                                 field->overrun);
  72                         if (!ret)
  73                                 return TRACE_TYPE_PARTIAL_LINE;
  74                 }
  75
  76                 ret = trace_seq_printf(s, "\n");
  77                 if (!ret)
  78                         return TRACE_TYPE_PARTIAL_LINE;
  79
  80                 return TRACE_TYPE_HANDLED;
  81         }
  82         return TRACE_TYPE_UNHANDLED;
  83 }
  84
  85 static struct tracer graph_trace __read_mostly = {
  86         .name        = "function-graph",
  87         .init        = graph_trace_init,
  88         .reset       = graph_trace_reset,
  89         .print_line = print_graph_function,
  90         .flags          = &tracer_flags,
  91 };
  92
  93 static __init int init_graph_trace(void)
  94 {
  95         return register_tracer(&graph_trace);
  96 }
  97
  98 device_initcall(init_graph_trace);