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 enum print_line_t initcall_print_line(struct trace_iterator *iter)
  49 {
  50         int ret;
  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         struct timespec calltime = ktime_to_timespec(it->calltime);
  56         struct timespec rettime = ktime_to_timespec(it->rettime);
  57
  58         if (entry->type == TRACE_BOOT) {
  59                 ret = trace_seq_printf(s, "[%5ld.%06ld] calling  %pF @ %i\n",
  60                                           calltime.tv_sec,
  61                                           calltime.tv_nsec,
  62                                           it->func, it->caller);
  63                 if (!ret)
  64                         return TRACE_TYPE_PARTIAL_LINE;
  65                 ret = trace_seq_printf(s, "[%5ld.%06ld] initcall %pF "
  66                                           "returned %d after %lld msecs\n",
  67                                           rettime.tv_sec,
  68                                           rettime.tv_nsec,
  69                                           it->func, it->result, it->duration);
  70                 if (!ret)
  71                         return TRACE_TYPE_PARTIAL_LINE;
  72                 return TRACE_TYPE_HANDLED;
  73         }
  74         return TRACE_TYPE_UNHANDLED;
  75 }
  76
  77 struct tracer boot_tracer __read_mostly =
  78 {
  79         .name           = "initcall",
  80         .init           = boot_trace_init,
  81         .reset          = stop_boot_trace,
  82         .ctrl_update    = boot_trace_ctrl_update,
  83         .print_line     = initcall_print_line,
  84 };
  85
  86
  87 void trace_boot(struct boot_trace *it)
  88 {
  89         struct ring_buffer_event *event;
  90         struct trace_boot *entry;
  91         struct trace_array_cpu *data;
  92         unsigned long irq_flags;
  93         struct trace_array *tr = boot_trace;
  94
  95         if (!trace_boot_enabled)
  96                 return;
  97
  98         preempt_disable();
  99         data = tr->data[smp_processor_id()];
 100
 101         event = ring_buffer_lock_reserve(tr->buffer, sizeof(*entry),
 102                                          &irq_flags);
 103         if (!event)
 104                 goto out;
 105         entry   = ring_buffer_event_data(event);
 106         tracing_generic_entry_update(&entry->ent, 0, 0);
 107         entry->ent.type = TRACE_BOOT;
 108         entry->initcall = *it;
 109         ring_buffer_unlock_commit(tr->buffer, event, irq_flags);
 110
 111         trace_wake_up();
 112
 113  out:
 114         preempt_enable();
 115 }