kernel/trace/trace_boot.c

   1 /*
   2  * ring buffer based initcalls tracer
   3  *
   4  * Copyright (C) 2008 Frederic Weisbecker <fweisbec@gmail.com>
   5  *
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/debugfs.h>
  10 #include <linux/ftrace.h>
  11
  12 #include "trace.h"
  13
  14 static struct trace_array *boot_trace;
  15 static int trace_boot_enabled;
  16
  17
  18 /* Should be started after do_pre_smp_initcalls() in init/main.c */
  19 void start_boot_trace(void)
  20 {
  21         trace_boot_enabled = 1;
  22 }
  23
  24 void stop_boot_trace(struct trace_array *tr)
  25 {
  26         trace_boot_enabled = 0;
  27 }
  28
  29 static void boot_trace_init(struct trace_array *tr)
  30 {
  31         int cpu;
  32         boot_trace = tr;
  33
  34         trace_boot_enabled = 0;
  35
  36         for_each_cpu_mask(cpu, cpu_possible_map)
  37                 tracing_reset(tr, cpu);
  38 }
  39
  40 static void boot_trace_ctrl_update(struct trace_array *tr)
  41 {
  42         if (tr->ctrl)
  43                 start_boot_trace();
  44         else
  45                 stop_boot_trace(tr);
  46 }
  47
  48 static int initcall_print_line(struct trace_iterator *iter)
  49 {
  50         int ret = 0;
  51         struct trace_entry *entry = iter->ent;
  52         struct trace_boot *field = (struct trace_boot *)entry;
  53         struct boot_trace *it = &field->initcall;
  54         struct trace_seq *s = &iter->seq;
  55
  56         if (entry->type == TRACE_BOOT)
  57                 ret = trace_seq_printf(s, "%pF called from %i "
  58                                        "returned %d after %lld msecs\n",
  59                                        it->func, it->caller, it->result,
  60                                        it->duration);
  61         if (ret)
  62                 return 1;
  63         return 0;
  64 }
  65
  66 struct tracer boot_tracer __read_mostly =
  67 {
  68         .name           = "initcall",
  69         .init           = boot_trace_init,
  70         .reset          = stop_boot_trace,
  71         .ctrl_update    = boot_trace_ctrl_update,
  72         .print_line     = initcall_print_line,
  73 };
  74
  75
  76 void trace_boot(struct boot_trace *it)
  77 {
  78         struct ring_buffer_event *event;
  79         struct trace_boot *entry;
  80         struct trace_array_cpu *data;
  81         unsigned long irq_flags;
  82         struct trace_array *tr = boot_trace;
  83
  84         if (!trace_boot_enabled)
  85                 return;
  86
  87         preempt_disable();
  88         data = tr->data[smp_processor_id()];
  89
  90         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
  91                                          &irq_flags);
  92         if (!event)
  93                 goto out;
  94         entry   = ring_buffer_event_data(event);
  95         tracing_generic_entry_update(&entry->ent, 0);
  96         entry->ent.type = TRACE_BOOT;
  97         entry->initcall = *it;
  98         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
  99
 100         trace_wake_up();
 101
 102  out:
 103         preempt_enable();
 104 }